Dear Readers, Welcome to Cardiology Objective Questions and Answers have been designed specially to get you acquainted with the nature of questions you may encounter during your Job interview for the subject of Cardiology Multiple choice Questions. These Objective type Cardiology Questions are very important for campus placement test and job interviews. As per my experience good interviewers hardly plan to ask any particular question during your Job interview and these model questions are asked in the online technical test and interview of many Medical Industry.
A. Closed chest massage is as effective as open chest massage.
B. The success rate for out-of-hospital resuscitation may be as high as 30% to 60%.
C. The most common cause of sudden death is ischemic heart disease.
D. Standard chest massage generally provides less than 15% of normal coronary and cerebral blood flow.
DISCUSSION: Closed chest massage is not as effective as open-chest massage in normalizing blood pressure or perfusion of vital organs, and closed chest massage does generally deliver 5% to 15% of normal coronary and cerebral blood flow. The success rate for out-of-hospital resuscitation has been as high as 30% to 60% when communities are prepared to institute CPR early after a cardiac arrest. Ischemic heart disease is the most common cause of sudden death.
A. Call for help.
B. Obtain airway.
C. Electrical cardioversion.
DISCUSSION: Basic life support does involve calling for help, obtaining an airway, and beginning ventilation before starting chest compression. Electrical cardioversion requires special equipment and trained personnel and thus is part of advanced cardiac life support.
A. External pacemaker.
B. Intravenous epinephrine, 10 ml. of 1:10,000.
C. Intravenous calcium gluconate, 10 ml. of 10% solution.
D. Intravenous atropine, 0.5 mg.
DISCUSSION: Recommended treatment for asystole is administration of atropine. If atropine is unsuccessful epinephrine is given. Ultimately cardiac pacing is necessary if atropine and epinephrine do not establish an adequate heart rate. Calcium has no clear role in treating asystole.
A. Comminuted tear of a single chamber.
B. Multiple-chamber injuries.
C. Coronary artery injury.
D. Tangential injuries.
DISCUSSION: Multiple studies in the literature confirm that injuries to the coronary arteries are the most important factor in determining outcome after a penetrating cardiac injury. Tangential injuries are the least serious. Injury to a single chamber—even if comminuted—or to multiple chambers is less likely to be fatal than are injuries that involve a major coronary artery.
A. Left anterior thoracotomy.
B. Right anterior thoracotomy.
C. Bilateral anterior thoracotomy.
D. Median sternotomy.
DISCUSSION: The subxyphoid incision is useful for determining if there is blood in the pericardium and if there is an intracardiac injury; however, exposure is extremely limited, and definitive repair can rarely be performed through the incision. Left (or right) anterior thoracotomy is easily performed, especially in the emergency room, and gives adequate exposure to certain areas of the heart. However, each has significant limitations in exposure. Either may be extended across the thoracotomy into the other side of the chest, thus producing a bilateral anterior thoracotomy. Exposure is excellent through this incision, and most injuries can be satisfactorily repaired through this approach. Most cardiac operations today are performed through median sternotomy incisions. If the patient is in the operating room, this incision is easily performed and always provides excellent exposure for all areas of the heart.
B. Distended neck veins.
C. Decreased heart sound.
D. All of the above.
DISCUSSION: Hypotension, increased venous pressure (distended neck veins), and decreased heart sounds make up the classic Beck's triad associated with cardiac tamponade. If these three findings are present in a person who has a penetrating chest wound, intracardiac injury is almost certain and operative intervention is mandatory.
A. Resection with end-to-end anastomosis.
B. Prosthetic patch aortoplasty.
C. Subclavian flap aortoplasty.
D. Prosthetic tube graft repair.
DISCUSSION: The most commonly used methods for coarctation repair are resection with anastomosis and subclavian flap aortoplasty. Both have been shown to provide adequate relief of the obstruction with acceptable rates of restenosis. The choice of repair depends on the patient's anatomy and the surgeon's experience. Patch aortoplasty was used frequently in the past; however, because of concern over restenosis and aneurysm formation it is no longer commonly performed. Prosthetic tube graft repair is avoided except in some complex cases and some cases of recoarctation.
A. Pulmonary artery sling.
B. Double aortic arch.
C. Anomalous origin of right subclavian artery from the descending aorta.
D. Cervical aortic arch.
DISCUSSION: Only the double aortic arch secondary to persistence of the right and left fourth aortic arches forms a true vascular ring. Pulmonary artery sling may cause symptoms that are due to compression of the trachea, and an anomalous right subclavian may cause dysphagia, but these anomalies do not constitute complete rings. Cervical aortic arch, which is thought to be secondary to persistence of the third aortic arch, is not a complete ring and usually is asymptomatic.
A. Posterior systolic murmur between the scapulas.
B. Diminished femoral pulses.
C. Elevated blood pressure in left arm as compared with right arm.
D. Peripheral cyanosis.
DISCUSSION: A systolic murmur that radiates posteriorly is characteristic of coarctation of the aorta. Coarctation produces obstruction to aortic flow, and thus the femoral pulse has a diminished volume with delayed upstroke. Hypertension in coarctation is multifactorial, but the most important factors are diminished renal flow (single clip, single kidney-Goldblatt model) and mechanical factors. If the right subclavian artery is anomalous and arises distal to the coarctation, blood pressure may be greater in the left arm than in the right. Isolated coarctation does not produce cyanosis.
A. Continuous murmur.
B. Hyperactive precordium with bounding peripheral pulses.
D. Diminished femoral pulses.
DISCUSSION: PDA causes a left-to-right shunt that produces left ventricular volume overload. Physical findings include evidence of hyperdynamic circulation with a prominent apical impulse and bounding peripheral pulses. The classic murmur of PDA is a continuous or mechanical murmur heard over the precordium and radiating to the medial third of the clavicle. Diminished femoral pulses are not seen with isolated PDA and would suggest other anomalies. PDA may result in hepatomegaly but does not cause jaundice.
A. Chest film.
B. Cardiac catheterization.
C. Retrograde aortography via an umbilical artery catheter.
D. Two-dimensional echocardiography with continuous-wave and color-flow Doppler echocardiography.
DISCUSSION: Echocardiography is the best method for confirming the diagnosis of a PDA. Two-dimensional echocardiography can demonstrate PDA and exclude associated anomalies. Doppler echocardiography can demonstrate the shunt, determine direction of shunting, and provide an estimate of shunt magnitude. The chest film is not particularly helpful and may be normal or show cardiomegaly with pulmonary congestion. In general, cardiac catheterization should be reserved for older patients and those with suspected associated anomalies or pulmonary hypertension.
B. Pulmonary vascular disease.
C. Cerebrovascular accident.
D. Congestive heart failure.
DISCUSSION: Coarctation of the aorta produces an obstruction to blood flow and hypertension, turbulent flow, and increased left ventricular afterload. There is an increased incidence of coronary artery disease. Prior to the introduction of effective techniques for relief of coarctation, the most common causes of death were endocarditis, aortic rupture, congestive heart failure, and cerebrovascular accident. Pulmonary vascular disease does not occur with isolated coarctation.
A. Secundum defect.
B. Sinus venosus defect.
C. Ostium primum defect.
D. Complete atrioventricular (AV) canal defect.
E. Coronary sinus defect.
DISCUSSION: Although partial anomalous return of the pulmonary veins can occur with any of the ASDs listed, it is particularly common with sinus venosus defects and is considered by many to be part of this lesion. The most common anomaly is drainage of the right superior pulmonary vein to the lateral aspect of the superior vena cava.
B. The compliance of the right and left ventricles.
C. The systemic oxygen saturation.
D. Right atrial pressure.
E. The presence or absence of an associated ventricular septal defect (VSD).
DISCUSSION: The direction of an intracardiac shunt is governed by the compliance of the downstream chambers. For an atrial level shunt, the compliance of the right and left ventricles and their ability to distend with increased volume during diastolic filling dictates the direction of the shunt flow. Since the right ventricle is usually a more compliant—and therefore more distensible—chamber than the left ventricle, flow across an ASD occurs from left to right across the open tricuspid valve during diastole. The size of an ASD does not correspond to the degree of shunt as long as the defect is large enough to be unrestrictive to flow. A large shunt can occur through a relatively small defect if the ventricular compliance is favorable.
A. Secundum defect
B. Sinus venosus defect
C. Ostium primum defect.
D. Coronary sinus defect.
DISCUSSION: Ostium primum defects, or “partial” AV canal defects, are commonly associated with a “cleft” of the anterior leaflet of the mitral valve. Depending on the deformity of the mitral valve, these defects can be accompanied by variable degrees of mitral insufficiency. This cleft of the mitral valve needs to be repaired at the same time that the defect is closed. Although other types of ASDs can be associated with mitral insufficiency, this is not as common. When mitral stenosis exists with a secundum ASD the condition is often referred to as Lutembacher's syndrome.
A. A secundum ASD.
B. A sinus venosus ASD with PAPVR.
C. An ostium primum ASD.
D. A complete AV canal defect.
DISCUSSION: Many patients with secundum ASDs have an incomplete bundle branch block on their ECG. This is in contradistinction to patients with ostium primum defects, who often have a left axis deviation. Although the ECG is not pathognomonic of the defect, the findings are sometimes helpful along with other clinical and diagnostic information toward elucidating the nature of the defect.
A. Secundum ASD.
B. Sinus venosus ASD with PAPVR.
C. An ostium primum ASD.
D. A complete AV canal defect.
DISCUSSION: Secundum ASDs can frequently be closed primarily, although the use of a prosthetic or pericardial patch is indicated for large defects. The other types of ASDs are more safely closed with a patch.
A. Partial anomalous pulmonary venous connection (PAPVC) to the superior vena cava.
B. Infracardiac (Type III) total anomalous pulmonary venous connection (TAPVC).
C. Pulmonary vein stenosis.
D. Cor triatriatum.
E. Supracardiac (Type I) TAPVC.
DISCUSSION: Obstruction to pulmonary venous return is the most important factor affecting circulatory function when pulmonary venous anomalies exist. This obstruction is most prevalent and severe in patients with infracardiac TAPVC, but it also occurs in as many as 50% of patients with supracardiac TAPVC and 20% of patients with intracardiac TAPVC to the coronary sinus. Obstruction to pulmonary venous return is also the primary pathophysiologic effect of both pulmonary vein stenosis and cor triatriatum. Obstruction, however, is rare with partial anomalous pulmonary venous connection, especially with the common form of PAPVC to the superior vena cava.
A. Complete heart block.
B. Acute pulmonary hypertensive crisis.
C. Pleural effusions.
D. Pulmonary venous obstruction.
DISCUSSION: In the early postoperative period after repair of obstructed forms of TAPVC, acute episodes of pulmonary hypertension may develop as a response to stress. To minimize this potentially fatal complication, infants are kept anesthetized with fentanyl and pancuronium for at least 48 hours. Residual or recurrent pulmonary venous obstruction occurs in only 5% to 10% of patients after TAPVC repair, but if identified it requires early reoperation. Reoperation is usually successful if the obstruction is at the level of the anastomosis. Unfortunately, in some cases, the obstruction is in the pulmonary veins and surgical relief is less successful. Although complete heart block and pleural effusions can occur after any cardiac operation, they rarely occur after TAPVC repair.
A. Perimembranous lesions are located in the region of the membranous portion of the interventricular septum near the anteroseptal commissure of the tricuspid valve.
B. Muscular VSDs are holes in the interventricular septum that are bordered by muscle on three sides and by the pulmonary and the aortic valve annulus superiorly.
C. VSD, in its isolated form, is the most commonly recognized congenital heart defect.
D. The conduction bundle runs along the posteroinferior rim of a perimembranous VSD.
DISCUSSION: Perimembranous VSDs occupy the area of the membranous portion of the interventricular septum adjacent to the anteroseptal commissure of the tricuspid valve. Often a remnant of the membranous portion of the interventricular septum (the membranous flap) is left hanging on the posteroinferior rim of the defect. The annulus of the tricuspid and aortic valves often form a part of the rim of the defect, but in some patients they are separated from the VSD by a thin rim of muscle tissue that protects the conduction bundle. Muscular VSDs have exclusively muscular rims on all four sides. VSDs in the outlet septum that extend to the annuluses of the aortic and pulmonary valves are called doubly committed or juxta-arterial defects. Isolated VSDs occur at an approximate rate of 2 per 1000 live births and represent 30% to 40% of all congenital heart malformations at birth. The conduction bundle in patients with perimembranous VSDs does run along the posteroinferior rim of the defect on the left ventricular side. Sutures used for repair of a perimembranous VSD should be placed well away from this area to avoid the creation of surgically induced complete heart block.
A. When coarctation of the aorta is associated with VSD, it most commonly occurs in infants with large lesions who have to undergo repair before age 3 months.
B. In some patients with VSD, aortic valve incompetence develops over time and progresses.
C. In the United States doubly committed or juxta-arterial VSDs are most commonly associated with aortic insufficiency.
D. PDA is present in approximately one fourth of infants with a VSD and concomitant congestive heart failure.
DISCUSSION: VSD in combination with severe coarctation of the aorta occurs in approximately 17% of patients. This combination is more common among infants with large VSDs undergoing operation before age 3 months. Aortic valve incompetence does develop over time in some patients with VSD, presumably as a result of progressive prolapse of the right aortic cusp through the defect. In the United States two thirds of patients with VSD and aortic insufficiency have perimembranous lesions and one third have a doubly committed or juxta-arterial lesion. In Japan, however, the reverse is true: two thirds have doubly committed or juxta-arterial lesions and one third have perimembranous lesions. A moderate- or large-sized PDA is associated with VSD in approximately 6% of patients of all ages; however, in infants with VSD and concomitant congestive heart failure, PDA is present in approximately 25%.
A. A large VSD is approximately the size of the pulmonary valve orifice or larger.
B. Large VSDs associated with high pulmonary blood flow result in an enlarged left atrium on chest x-ray.
C. Patients with small (restrictive) VSDs tend to have normal right ventricular and pulmonary arterial pressures with normal pulmonary vascular resistance and no evidence of pulmonary vascular disease.
D. A pulmonary vascular resistance greater than 10 to 12 units per sq. m. is considered a contraindication to operation.
DISCUSSION: A large VSD is approximately the size of the aortic valve orifice or larger and causes systemic right ventricular systolic pressures. In the absence of right ventricular outflow tract obstruction, the pulmonary artery systolic pressure will also be systemic in the presence of a large VSD. Large VSDs associated with a high pulmonary blood flow do result in an enlarged left atrium because of increased pulmonary venous return. When marked enlargement of the left atrium is present in a patient suspected of having a VSD, the presence of coexisting mitral valve regurgitation should also be considered. Patients with small VSDs do have normal right ventricular and pulmonary arterial pressures. There is only a slight elevation of pulmonary blood flow relative to the systemic flow, and the pulmonary vascular resistance is normal without evidence of pulmonary vascular disease. At any age, the presence of pulmonary vascular disease so severe that the pulmonary vascular resistance is fixed and greater than 10 to 12 units per sq. m. is considered a contraindication to operation.
A. Spontaneous closure of VSDs occurs in 25% to 50% of patients during childhood.
B. Tachypnea and failure to thrive are symptoms frequently associated with large VSDs.
C. Patients with normal pulmonary vascular resistance and left-to-right shunting across the VSD have Eisenmenger's complex.
D. Patients with a large VSD and low pulmonary vascular resistance can present with a middiastolic murmur at the apex.
DISCUSSION: Spontaneous and complete closure of VSDs, even large ones, has been estimated to occur in 25% to 50% of patients during childhood. The probability of eventual spontaneous closure is inversely related to the age at which the patient is observed. Tachypnea, poor feeding, growth failure, recurrent respiratory infections, exercise intolerance, and severe cardiac failure may develop in patients with large VSDs. Patients with Eisenmenger's complex are cyanotic, polycythemic, and severely limited in their exercise tolerance, owing to markedly elevated pulmonary vascular resistance associated with a predominantly right-to-left shunt across the VSD. A middiastolic murmur can be present at the apex in patients with a large VSD associated with low pulmonary vascular resistance. This indicates high pulmonary blood flow with a large flow across the mitral valve into the left ventricle.
B. Intracardiac repair is advisable for patients with intractable symptoms and for asymptomatic infants with evidence of increasing pulmonary vascular resistance.
C. Complete heart block is a common complication.
D. Hospital mortality after repair of VSD in infants approaches 20%.
DISCUSSION: The right atrial approach is preferred for the repair of most perimembranous VSDs. Prompt intracardiac repair is indicated for infants with large defects, large shunts, and pulmonary hypertension who present with intractable left ventricular failure, recurrent pulmonary infections, severe growth failure, or evidence of increasing pulmonary vascular resistance. In the modern era, complete heart block requiring a permanent pacemaker is a very uncommon complication of surgical closure of a ventricular septal defect. Hospital mortality after closure of a VSD currently approaches zero. While in earlier years younger age was an incremental risk factor for hospital death in some surgical experiences, this risk has been neutralized during the past decade.
C. Dextroposition of the aorta.
D. Pulmonary stenosis.
E. Right ventricular hypertrophy.
DISCUSSION: Although ASD is a frequent component of tetralogy of Fallot, it was not included by Fallot as part of his classic tetralogy. Occasionally, the inclusion of an ASD prompts use of the term pentalogy of Fallot. The other four anomalies listed were all mentioned by Fallot in his original description of this defect.
A. The size of the ASD.
B. The size of the VSD.
C. The degree of pulmonary stenosis.
D. The amount of aortic overriding.
DISCUSSION: The VSD in tetralogy of Fallot is nonrestrictive, and therefore its size does not affect the degree of shunting that can occur. Likewise, an ASD, which may or may not be a component of tetralogy of Fallot, can provide right-to-left shunting at the atrial level but is not the main contributor to the cyanosis of this disease. The degree of right-to-left shunt across the VSD is dictated by the variable compliance of the downstream chambers, and the increased resistance imposed by severe pulmonary stenosis creates greater amounts of right-to-left shunting and, therefore, more intense cyanosis. The position of the aorta in relation to the VSD is not important as long as no subaortic obstruction exists.
A. Absence of the left pulmonary artery.
B. A right aortic arch.
C. A retroesophageal subclavian artery.
D. Anomalous origin of the left anterior descending coronary artery from the right coronary artery.
E. Primary pulmonary hypertension.
DISCUSSION: The first four defects listed occasionally are associated with tetralogy of Fallot. A right aortic arch is seen in 25% of patients with that lesion. Anomalous coronary arteries or a retroesophageal subclavian artery are found in as many as 5% to 10% of patients. Absence of a pulmonary artery is unusual but can present in as many as 3% of patients. Pulmonary hypertension is distinctly unusual with tetralogy of Fallot unless the patient has had excessive pulmonary blood flow from collaterals or systemic-to-pulmonary artery shunts for a long time. It is because these patients usually do not have pulmonary hypertension that infant correction with transannular patches can be performed with such great success.
A. Maintenance of ductal patency with prostaglandins (PGE 1) to provide pulmonary blood flow while the baby is transferred to an institution equipped to provide more definitive therapy.
B. Banding of the pulmonary artery in an acyanotic patient with tetralogy of Fallot to control pulmonary blood flow and prevent the development of pulmonary hypertension.
C. Placement of a subclavian-to-pulmonary artery shunt on the side opposite the aortic arch in a 3-day-old infant with severe cyanosis.
D. Closure of the VSD and transannular patching of the right ventricle onto the main pulmonary artery in a 2-day-old infant.
DISCUSSION: Patients with tetralogy of Fallot who do not appear cyanotic still have mild arterial hypoxemia by arterial blood gas determination. Patients with tetralogy of Fallot rarely have excessive pulmonary blood flow, and the development of pulmonary hypertension is not a concern in this population. Banding of the pulmonary artery is never a consideration in patients with tetralogy of Fallot, since the predominant physiologic effect of the defect results from too little pulmonary blood flow to begin with. Acyanotic patients with tetralogy of Fallot (“pink tets”) can usually be followed for several months and their defects repaired electively as a first-stage procedure (usually by age 6 months). All of the other therapies are appropriate treatment for babies with tetralogy of Fallot. Prostaglandins maintain patency of the ductus arteriosus, providing an anatomic systemic-to-pulmonary artery shunt that sustains pulmonary blood flow until a more permanent surgical solution can be provided. The advent of prostaglandin therapy has enabled numerous critically ill infants to become stabilized enough to reach a tertiary care institution and receive proper surgical therapy who might not otherwise have survived had it not been for the ability of pulmonary blood flow to be maintained through the reversal of duct closing. The choice of palliative shunting or total anatomic correction rests largely with the experience and skill of the surgical team and is dictated in part by the anatomy of the pulmonary arteries. Either of these options is acceptable.
A. The size of the ASD.
B. The baby's age at presentation.
C. The size of the right ventricular cavity and tricuspid valve.
D. The presence of a tricuspid—as opposed to a bicuspid—pulmonary valve.
E. The level of hypoxemia at presentation.
DISCUSSION: The long-term outcome for babies with pulmonary atresia and intact ventricular septum depends on the ability to convert the cardiac circulation into a two-ventricle versus one-ventricle physiology. Patients with a good-sized right ventricle and tricuspid valve can often be treated with pulmonary valvotomy or right ventricular outflow patching alone and can have a fairly acceptable outcome. Patients with a small right ventricle that cannot provide adequate pumping to the pulmonary bed and is often associated with a small tricuspid valve annulus may need to be staged toward a Fontan procedure—and, consequently, a less acceptable outcome. The size of an ASD is not relevant except that in patients with this syndrome, the right side of the heart will decompress across the ASD until antegrade flow can be established. Therefore, an ASD in some part is an essential feature of this lesion. The degree of arterial hypoxemia, the nature of the pulmonary valve, and the patient's age at presentation may all be factors that relate to clinical management, but they do not imply specific consequences with respect to long-term outcome.
A. A VSD is usually present.
B. In the Taussig-Bing type of double-outlet right ventricle, the VSD is usually noncommitted.
C. Patients with double-outlet right ventricle and a subaortic VSD usually have pulmonary stenosis.
D. Patients with double-outlet right ventricle with a subpulmonary VSD (Taussig-Bing malformation) tend to mimic patients with transposition of the great arteries and VSD in their presentation and natural history.
DISCUSSION: A VSD is usually present in patients with double-outlet right ventricle and is the only outlet from the left ventricle. Both great arteries may arise totally from the right ventricle, or one or both may overlie the ventricular septum immediately above the VSD. To categorize the heart as having a double-outlet right ventricle, more than 50% of each great artery must arise from the right ventricle. In the Taussig-Bing type of double-outlet right ventricle, the VSD is related to the pulmonary valve annulus and is termed a subpulmonary defect. Additional morphologic characteristics peculiar to this entity have been described. Most patients with double-outlet right ventricle and a subaortic VSD have concomitant pulmonary stenosis that protects the lungs from pulmonary vascular disease and also results in a clinical course similar to that of patients with tetralogy of Fallot. In the absence of pulmonary stenosis the presentation, clinical course, and natural history of the Taussig-Bing malformation are similar to those of transposition of the great arteries with VSD. Cyanosis is present, usually from birth, since streaming directs the desaturated systemic venous return toward the aorta and the oxygenated left ventricular blood toward the pulmonary artery. These patients tend to develop early congestive heart failure and can develop severe pulmonary vascular disease early in life. They usually experience symptoms within the first few months of life.
A. In double-outlet right ventricle with a subaortic or doubly committed VSD, a tunnel-type repair connecting a committed VSD with its respective great artery is usually employed.
B. Repair of the Taussig-Bing malformation can be accomplished using an intraventricular tunnel technique or by performing a straight patch closure of the VSD combined with an arterial switch procedure.
C. The hospital mortality rate is highest when a subaortic VSD is present.
D. Some hearts with double-outlet right ventricle and a noncommitted VSD must be repaired using a modification of the Fontan procedure.
DISCUSSION: When the VSD is subaortic or doubly committed, the tunnel-type repair connects the left ventricle via the VSD and tunnel to the aorta. The Taussig-Bing malformation can be repaired using an intraventricular tunnel technique described by Kawashima. This repair can best be accomplished when the great arteries are in a more or less side-by-side relationship with the aorta to the right of the pulmonary artery. The infundibular septum is generously resected and the VSD is connected to the aorta by an intraventricular tunnel that runs posterior to the pulmonary artery. The most common approach for the repair of the Taussig-Bing malformation involves patch closure of the VSD to the pulmonary artery. This creates transposition of the great arteries with an intact interventricular septum. An arterial switch procedure then establishes ventriculoarterial concordance. Of all the types of double-outlet right ventricle the hospital mortality is lowest when a subaortic or doubly committed VSD is present. Double-outlet right ventricle is associated with a noncommitted VSD in approximately 10% of patients in surgical series. The repair of this subset of patients is associated with a relatively high mortality, as compared with the results obtained after repair of other forms of double-outlet right ventricle. At times, because of the remote location of the VSD and because of other compelling anatomic features, complete repair cannot be performed. In this case, a modification of the Fontan procedure must be employed.
A. Creation of a systemic artery–to–pulmonary artery shunt.
C. Creation of a bidirectional superior cavopulmonary anastomosis.
D. Pulmonary artery banding.
E. Fontan procedure.
DISCUSSION: Initial management of newborn infants with tricuspid atresia is determined by the anatomic and physiologic factors that affect the balance of pulmonary and systemic blood flow. Infants with severely limited pulmonary blood flow and arterial oxygen saturations of less than 70% should be stabilized with PGE 1 to maintain patency of the ductus arteriosus until a systemic-to-pulmonary artery shunt can be performed. Patients with unobstructed pulmonary blood flow may exhibit only mild cyanosis but suffer from significant congestive heart failure. Many of these patients are best managed by pulmonary artery banding to decrease the volume overload on the left ventricle and to prevent the early development of irreversible pulmonary vascular disease. Some patients with moderate restriction of pulmonary blood flow may have balanced delivery of blood to the systemic and the pulmonary circulation. These patients can be carefully followed until such time as an imbalance develops or they become candidates for a bidirectional superior cavopulmonary (Glenn) anastomosis or a Fontan procedure. The normally high pulmonary vascular resistance present in the first month of life precludes the performance of either the Glenn or the Fontan procedure in the newborn.
A. Patient age of 25 years.
B. Severe mitral insufficiency.
C. Left ventricular end-diastolic pressure of 18 mm. Hg.
D. Right pulmonary artery stenosis.
E. Pulmonary vascular resistance of 6 Woods units.
DISCUSSION: Good ventricular function and low pulmonary vascular resistance are essential requirements for a successful Fontan procedure. The Fontan operation should not be performed when ventricular ejection fraction is less than 30% or ventricular end-diastolic pressure is greater than 15 mm. Hg. Pulmonary vascular resistance in excess of 4 Woods units should also be considered an absolute contraindication for Fontan correction. Age at the time of Fontan procedure does not appear to be a major risk factor, except before age 2 years. Although patients who have survived into the third or fourth decade are likely to have ventricular dysfunction, a Fontan procedure can be performed successfully in these older patients if ventricular function and pulmonary vascular resistance meet the above criteria. In patients with tricuspid atresia a competent mitral valve is important for satisfactory cardiac output after the Fontan procedure. The presence of severe mitral insufficiency, however, should not necessarily contraindicate the procedure. In these cases it is recommended that the mitral valve be repaired or replaced in combination with the creation of a bidirectional superior cavopulmonary anastomosis. A completion Fontan operation is performed later. Distorted or stenosed pulmonary arteries are common sequelae of systemic-to-pulmonary artery shunts and may result in unsatisfactorily high pulmonary vascular resistance. In most cases, these stenoses can be repaired at the time of Fontan correction or with a bidirectional superior cavopulmonary anastomosis.
A. Intravenous administration of PGE 1.
B. Supplemental oxygen.
C. Routine intubation and mechanical ventilation to achieve a PCO 2 between 30 and 35 mm. Hg.
D. Cardiac catheterization and balloon atrial septostomy.
DISCUSSION: Postnatal stabilization of infants with hypoplastic left heart syndrome requires patency of the ductus arteriosus and balance of the systemic and the pulmonary circulation. Because the ductus is the only pathway from the right ventricle to the systemic circulation, duct patency must be maintained with intravenous PGE 1. To minimize the workload on the single ventricle and ensure adequate delivery of oxygen to the tissues, an equal delivery of blood to both the lungs and the body is sought. The normal postnatal decrease in pulmonary vascular resistance often results in overperfusion of the pulmonary circulation and underperfusion of the systemic circulation. Maneuvers that further decrease pulmonary vascular resistance, such as the addition of supplemental oxygen, lowering the PCO 2 to less than 35 mm. Hg, or eliminating any resistance at the atrial septum by balloon septostomy only worsens the imbalance.
A. Provides early relief of volume load on the single right ventricle.
B. Increases peripheral oxygen saturations to greater than 90%.
C. Permits concomitant repair of pulmonary artery or aortic arch stenoses.
D. Improves mortality and morbidity of subsequent Fontan procedure.
DISCUSSION: After the first-stage reconstructive (Norwood) procedure, the circulation is inherently inefficient because of the obligatory recirculation of a portion of both saturated and desaturated blood. Closure of the arterial shunt and creation of a bidirectional Glenn anastomosis eliminates this inefficient recirculation and significantly diminishes the volume load on the single right ventricle. Distorted and stenosed central pulmonary arteries or aortic arch obstructions should be repaired at the same time the bidirectional Glenn procedure is performed. In almost all series the mortality of the Fontan procedure has decreased since the adoption of the three-stage approach for hypoplastic left heart syndrome. Because systemic and pulmonary venous blood continue to mix in the right atrium after a bidirectional Glenn procedure, cyanosis persists with peripheral oxygen saturations between 75% and 85%.
A. Most infants survive without operations until late childhood.
B. Most infants present with cyanosis.
C. Most infants present with congestive heart failure.
D. Repair requires a conduit from right ventricle to pulmonary arteries.
DISCUSSION: While an occasional child survives to age 3 or 4 years, without either palliative or totally corrective surgical treatment few live past early infancy. The lesion is one of excessive pulmonary blood flow because of the origin of the pulmonary arteries from the truncus arteriosus; physiologically, the pulmonary arteries arise directly from the aorta. Although the aortic saturation can never be 100% because of some element of bidirectional shunting at the VSD, the physiologic manifestations are congestive heart failure and excessive pulmonary blood flow rather than cyanosis. The congestive heart failure becomes severe as pulmonary vascular resistance drops. If congestive heart failure later improves spontaneously, it is because of the development of pulmonary vascular disease. Complete repair always requires closure of the VSD, detachment of the pulmonary arteries from the common trunk, and re-establishment of an outflow tract from the right ventricle to the pulmonary artery. This conduit usually contains a valve and can be either a homograft or a synthetic conduit containing a porcine valve.
B. Abnormal origin of pulmonary arteries.
C. Subaortic stenosis.
D. Single ventricular outflow valve.
DISCUSSION: By definition, a VSD is always present immediately beneath the truncal valve. The pulmonary arteries arise abnormally from the single trunk, which is due to failed partitioning of the embryonic conus during the first few weeks of fetal development. In the classification of Collett and Edwards, Type I truncus arteriosus has a single arterial trunk giving rise to an aorta and a main pulmonary artery; in Type II the right pulmonary arteries arise immediately adjacent to one another from the dorsal wall of the truncus; in Type III the right and left pulmonary arteries originate from either side of the truncus; and in Type IV the proximal pulmonary arteries are absent and pulmonary blood flow is by way of major aortopulmonary atresia and is no longer considered truncus arteriosus. Subaortic stenosis cannot occur in this anomaly. The single ventricular outflow valve is the truncal valve. It may contain from two to six cusps, but most often there are three and, next most often, four.
A. PGE 1 infusion to maintain duct patency.
B. Administration of intravenous fluid to increase intravascular volume.
C. Hyperventilation to decrease pulmonary resistance.
D. Oxygen administration to increase arterial oxygen tension.
E. Atrial balloon septostomy to improve atrial mixing.
DISCUSSION: Because with transposition of the great vessels the systemic and the pulmonary circulations exist in parallel rather than in series, survival depends on mixing between pulmonary and systemic circulations. Initially infants with transposition and intact atrial septum survive because of aortopulmonary flow through PDA, which may be maintained with prostaglandin infusions. Although increased pulmonary flow may cause enlargement of the left atrium and stretching of the foramen ovale resulting in atrial-level mixing of oxygenated and nonoxygenated blood, inadequate mixing at the atrial level will result in marginal tissue oxygenation, which does not improve with oxygen administration. Atrial balloon septotomy results in improved admixture and oxygen delivery in these patients and should be performed promptly if peripheral acidemia and severe cyanosis are present. Relative dehydration may decrease the degree of interatrial shunting and volume infusion often improves hemodynamics in infants. Decreased pulmonary vascular resistance may increase pulmonary blood flow at the expense of systemic blood flow and alter the loading conditions of the left ventricle, which may complicate early arterial repair.
A. Age older than 6 weeks with a left ventricular pressure of less than 50% of systemic pressure.
B. Dynamic left ventricular outflow tract obstruction.
C. Intramural coronary artery anatomy.
D. Valvar pulmonic stenosis.
E. Subpulmonary VSD.
DISCUSSION: Single-stage arterial switch procedure for reconstruction of transposition of the great vessels, with or without associated VSD has become the standard of treatment in the majority of cardiac centers. Contraindications to arterial switch repair include fixed types of left ventricular outflow tract obstruction, including valvar pulmonic stenosis, which would render the systemic semilunar valve stenotic or incompetent. Anatomic abnormalities without stenosis, such as a bicuspid valve, however, are suitable for surgical correction. The location of VSD does not affect surgical outcome, and most VSDs can be approached adequately through the right atrium or the anterior great vessel. Most dynamic forms of left ventricular outflow tract obstruction are often relieved partially or completely by realignment of the ventricular septum with the hemodynamic changes following successful arterial switch repair. When, however, the left ventricle has not been prepared to sustain the pressure load of the systemic circulation by the decrease in pulmonary vascular resistance that occurs in the first few weeks of life and when the ventricular pressure is less than 50% of the systemic ventricular pressure, one-stage repair is contraindicated, and staged repair with pulmonary banding and shunt followed by arterial switch must be contemplated.
A. Atrial arrhythmias.
B. Systemic or pulmonary venous obstruction.
C. Right ventricular outflow tract obstruction.
D. Systemic ventricular failure.
E. Progressive elevation of pulmonary vascular resistance.
DISCUSSION: The atrial repair of transposition of the great arteries—rerouting systemic and pulmonary venous blood at the atrial level—results in the right ventricle's becoming the systemic ventricle. This results in an anatomic right ventricle with abnormal geometry sustaining the afterload of a more ideally suited left ventricle. Long-term complications of ventricular dilatation, AV valve regurgitation, and right ventricular failure have been reported in as many as 10% of patients many years following the atrial operation. The multiple suture lines in the atrium have been associated with a high incidence of late atrial arrhythmias and a low incidence of sinus rhythm following the Mustard and Senning operations. These complications do not appear to be as frequent with the arterial switch repair. In addition, the complicated interatrial baffles have been associated with pulmonary or systemic venous baffle obstruction. Because the right ventricular outflow tract is not addressed during an atrial switch operation, right ventricular outflow tract obstruction is not a recognized complication following the repair. Right ventricular outflow tract and supravalvar pulmonic stenosis, however, have been reported in patients after the arterial switch repair, owing to the reconstruction of the right ventricular outflow tract in that operation. Although progression of pulmonary arterial obstruction has rarely been reported following early repair with the atrial or the arterial switch procedure, it is an unusual complication if operation is undertaken in infancy. Delayed repair beyond age 6 months to 1 year, however, has been associated with a higher incidence of progressive development of pulmonary vascular obstructive disease. The rapidity of the development of pulmonary vascular disease is increased by the coexistence of a VSD.
A. It is most often due to commissural fusion of a trileaflet valve.
B. It may be associated with coarctation of the aorta, PDA, and mitral stenosis.
C. It can be managed medically until the child is large enough to undergo aortic valve replacement.
D. Success of valvotomy is determined by the adequacy of the left ventricle.
DISCUSSION: Critical aortic stenosis in the neonate most often presents in the first week of life with severe and progressive congestive heart failure and may be associated with coarctation of the aorta, PDA, and mitral stenosis. The prognosis is poor unless valvotomy can be performed expeditiously. Medical management cannot stabilize these infants for valve replacement at a later age. Infants whose left ventricle is too small to sustain the systemic circulation are unlikely to survive aortic valvotomy and, thus, should be managed as patients with hypoplastic left heart syndrome. The aortic valve in neonatal aortic stenosis is most commonly unicuspid or bicuspid.
A. Enlargement of the aortic annulus.
B. Incision of fused commissures.
C. Insertion of a porcine valve prosthesis.
D. Transfer of the pulmonary valve to the aortic position.
DISCUSSION: The majority of older children with aortic stenosis and significant transvalvular gradients can be treated successfully by aortic valvotomy. This can be done percutaneously with balloon dilatation or surgically with direct visualization of the aortic valve and incision of the fused commissures. Aortic valve replacement is rarely necessary as a primary procedure but may be required in children who develop progressive aortic insufficiency after a previous intervention. When valve replacement is performed it is desirable to insert the largest prosthesis possible, to allow for growth. Enlargement of the aortic annulus is commonly performed for this purpose. If a true valve prosthesis is employed, a mechanical valve is preferred. Durability of xenograft valves in children is limited owing to early calcification and leaflet degeneration. The pulmonary autograft technique may be the best method of aortic valve replacement in children. With this operation the patient's own pulmonary valve is transferred to the aortic position and a pulmonary allograft is inserted to replace the pulmonary valve. Although the pulmonary autograft may not achieve the long-term durability of a mechanical valve, the patient does not face the long-term complications of thromboembolism and bleeding imposed by a mechanical valve and lifelong anticoagulation.
A. Most patients present in early infancy with severe congestive heart failure.
B. An ejection click is a specific physical sign of subaortic stenosis.
C. The subaortic membrane is approached surgically via the aorta and aortic valve.
D. A concomitant septal myectomy decreases the incidence of recurrent subaortic stenosis.
DISCUSSION: Subaortic stenosis is rarely encountered in neonates. Most often it is discovered in an asymptomatic child during a routine physical examination. A loud crescendo–decrescendo systolic murmur without an ejection click is usually noted. The presence of an ejection click is more consistent with isolated valvular aortic stenosis. Discrete subaortic stenosis is approached surgically with cardiopulmonary bypass, aortic cross-clamping, and cardioplegic arrest. The aorta is opened and the aortic valve leaflets are retracted, exposing the fibrous membrane. The fibrous ring is carefully excised, taking care to avoid injury to the anterior leaflet of the mitral valve and the penetrating conduction bundle. Once the subaortic membrane is excised a septal myectomy further opens the left ventricular outflow tract and diminishes the likelihood of recurrent subaortic stenosis.
A. Propranolol and verapamil.
B. Aortic valve replacement.
C. Dual-chamber sequential pacing.
D. Combined septal myectomy and mitral valve plication.
DISCUSSION: The majority of patients with hypertrophic obstructive cardiomyopathy are treated medically with beta-blockers such as propranolol and calcium channel blockers such as verapamil. Patients whose symptoms do not respond to medical therapy are treated surgically with a transaortic septal myectomy. Recent reports indicate that simple plication of the anterior leaflet of the mitral valve performed in addition to the septal myectomy further opens the left ventricular outflow tract by eliminating systolic anterior motion of the mitral valve. Aortic valve replacement is not an appropriate treatment for hypertrophic obstructive cardiomyopathy. Some patients who are poor surgical candidates may experience relief of symptoms and left ventricular outflow gradients with dual-chamber permanent pacing. Appropriate pre-excitation of the ventricular septum can prompt the septum to move away from the left ventricular wall during systole and open the outflow tract.
A. Surgical repair is indicated only when the systolic gradient exceeds 75 mm. Hg.
B. Simple excision of the supravalvular membrane results in satisfactory relief of the stenosis in most patients.
C. The diffuse form of supravalvular aortic stenosis may cause obstruction to branches of the aortic arch.
D. Reoperation after repair of discrete supravalvular aortic stenosis is rare unless abnormalities of the valve itself also exist.
DISCUSSION: Supravalvular aortic stenosis is a progressive disease and should be repaired surgically if symptoms are present or the systolic gradient exceeds 50 mm. Hg. In addition to excision of the supravalvular membrane, a patch of dacron or pericardium must be placed across the area of narrowing and down into at least one of the sinuses of Valsalva. Reoperation is rare after this procedure unless associated aortic valve disease is also present. In the diffuse form of the disease the thickening of the aortic wall commonly results in significant luminal narrowing of the ascending aorta and its major branches.
E. Over 2,000,000.
DISCUSSION: It is estimated that approximately 7,000,000 Americans currently have symptomatic coronary artery disease. Of these some 1,500,000 experience myocardial infarction annually and approximately 500,000 die each year from complications.
A. The right coronary artery.
B. The left coronary artery.
C. The anterior descending coronary artery.
D. The circumflex coronary artery.
DISCUSSION: In order of frequency, the anterior descending coronary artery is the most commonly involved with atherosclerosis, followed by the right coronary, the circumflex, and the left main coronary artery.
A. There is a rich and quite effective collateral circulation in the coronary arterial bed.
B. The coronary arterial bed has minimal effective collaterals.
C. The coronary arterial bed is an absolute example of anatomic end-arteries.
DISCUSSION: The collateral circulation to the heart is relatively poor. In the human heart there are few natural collaterals of sufficient diameter for delivery of a significant quantity of blood. Most of the collaterals are approximately 200 mm. or smaller, and channels of this size cannot conduct significant quantities of blood for cardiac requirements. There is no absolute example of anatomic end-arteries in humans. While the magnitude of arterial collateral circulation varies considerably, all organs have some collaterals.
E. Less than 20%.
DISCUSSION: The heart has an unusually high rate of oxygen utilization and consumes approximately two thirds of the oxygen in the arterial blood. The oxygen saturation of the blood in the coronary sinus is usually about 30% to 35% and varies with the magnitude of cardiac disease. The body as a whole extracts approximately 25% of the oxygen it receives, thus emphasizing the great need of the heart for oxygen at rest as well as at exercise.
A. Reduce the incidence of myocardial infarction.
B. Significantly relieves angina symptoms.
C. Statistically improve the life span.
D. Improve the ejection fraction of the left ventricle in many patients in whom it is significantly depressed preoperatively.
DISCUSSION: In a variety of studies, coronary bypass procedures have been demonstrated to reduce the incidence of subsequent myocardial infarction as well as to relieve significantly anginal symptoms. They also improve the life span of most patients as well as the ejection fraction of the left ventricle in those in whom it was depressed preoperatively.
A. A 60-year-old man with class II angina, 75% proximal right coronary artery lesion, and normal ventricular function.
B. A 60-year-old man with unstable angina, three-vessel disease, and an ejection fraction of 35%.
C. A 60-year-old nondiabetic man with class III angina symptoms and focal discrete lesions in the mid-right coronary artery and mid-left circumflex artery.
D. A 60-year-old man with diabetes, class IV angina, 75% proximal left anterior descending and 75% proximal right coronary artery obstruction, and left ventricular ejection fraction of 60%.
DISCUSSION: CABG has been shown to prolong patient survival compared with medical therapy in those patients with left main occlusive disease and those with three-vessel or two-vessel disease with proximal left anterior descending involvement in association with class III or greater anginal symptoms, impaired ejection fraction, or easily inducible ischemia with exercise. Although percutaneous transluminal coronary angioplasty (PTCA) appears to be comparable to CABG in nondiabetic patients, patients with diabetes appear to have a significant survival advantage when CABG is used. Similarly, patients with more extensive coronary artery disease are better treated with CABG than with PTCA.
D. Less than 15%.
DISCUSSION: Although the mortality rate following sternal infections with mediastinitis formerly was high, it is now greatly reduced. In most series, mediastinitis is cured in more than 90% of patients who are treated aggressively with débridement and placement of muscle flaps or omentum into the mediastinum to speed wound healing.
D. Less than 5%.
DISCUSSION: Following improvements in myocardial protection and coronary grafting techniques, perioperative myocardial infarction now occurs in less that 2% to 4% of patients in most series.
D. 2% or less.
DISCUSSION: Postmortem studies indicate that 8% to 10% of fatal cases of myocardial infarction are due to rupture of the heart. In addition, infarction of the interventricular septum with subsequent formation of a ventricular septal defect occurs in 1% to 2% of patients with acute myocardial infarction. The usual interval between the acute infarction and septal rupture—4 to 12 days—correlates with the histologic finding of maximal cardiac muscle degeneration.
A. Multivessel disease.
B. Rescue atherectomy.
C. Cardiogenic shock prior to CABG.
D. Previous bypass surgery.
E. All of the above.
A. The operative mortality is higher for Y but the incidence of perioperative myocardial infarction is unchanged between X and Y.
B. The operative mortality is unchanged between X and Y but the perioperative incidence of myocardial infarction is higher in Y.
C. The operative mortality and perioperative incidence is higher in X than in Y.
D. The operative mortality and perioperative incidence of myocardial infarction are no different for X and for Y.
A. The risk for morbidity and mortality from reoperative coronary bypass grafting is increased.
B. Left ventricular function is better preserved at the time of reoperation.
C. The risk of sternal wound complications is greatly increased if the contralateral IMA is harvested at the time of reoperation.
D. A light clamp should be applied to the IMA pedicle to limit cardiac warming during cardioplegic arrest at the time of reoperation.
E. A functional study demonstrating a large portion of myocardium at risk should be obtained before reoperation.
DISCUSSION: Patients who have an intact IMA graft should have severe anginal symptoms and a significant portion of myocardium at risk before reoperative coronary bypass grafting is considered. A functional study may better define the proportion of myocardium at risk for ischemia and infarction. Patients with an intact IMA graft are less likely to require reoperation, but if stenosis distal to the IMA and disease in other vein grafts have progressed or if a large portion of myocardium is at risk, reoperation is recommended. The presence of an intact IMA is not a contraindication to reoperation; in fact, this population of patients have better-preserved ventricular function and are, perhaps, better candidates for reoperation. Placement of an IMA graft at the time of the first operation was critically important, neutralizing the adverse effects of elevated serum cholesterol, hypertension, and smoking on reoperation-free survival. The risk of damaging an intact IMA graft is 3% to 5%. A lateral projection of the IMA at cardiac catheterization will define its course, particularly in relation to the sternum, to allow more careful sternal re-entry. The IMA should be minimally dissected and a light clamp applied during cardioplegic arrest to limit cardiac warming and improve myocardial protection. The IMA may be detached and recycled if needed. The use during reoperation of the contralateral IMA does not increase the risk of sternal wound complications.
A. Operative morbidity and mortality are increased over those for primary CABG.
B. Mortality most often stems from cardiac causes after reoperation.
C. Survival of patients after hospital discharge following coronary reoperation is nearly equivalent to survival after primary CABG.
D. Compared to primary CABG, return of anginal symptoms is delayed after reoperative CABG.
E. Myocardial protection and the risk of myocardial infarction in reoperation are complicated by increased noncoronary collaterals, patent atherosclerotic saphenous vein grafts, and more diffuse coronary atherosclerosis.
DISCUSSION: The mortality and morbidity after reoperative CABG are approximately two to three times that of primary CABG. In contrast to primary CABG, where the majority of deaths are a result of failure of other organ systems, 75% to 85% of deaths after reoperative CABG are due to cardiac causes. The increased risk of reoperation results from more advanced native vessel disease, a longer cross-clamp time, a longer cross-clamp time per graft, a longer time to initiate cardiopulmonary bypass, and increased blood loss. The increased frequency of pulmonary complications, myocardial infarction, neurologic injury, and death, stems from the technical factors of reoperation and the characteristics of the patient population. Technical factors include difficulty in finding targets secondary to pericardial reaction and more diffusely diseased vessels, the risks of injuring the heart or great vessels on sternal re-entry, increased blood loss and risk of requiring transfusion, less available conduit for bypass, and greater difficulty in providing optimal myocardial protection. Characteristics of this patient population that increase risks include advanced age and diminished ventricular function. While survival after reoperation is nearly equivalent to that after primary CABG, angina symptoms return at twice the frequency in the first year after operation (47% versus 20%) then return at a similar annual rate (2% to 3%).
A. Gated equilibrium techniques provide more accurate measurements of ejection fraction than initial-transit methods.
B. Left ventricular imaging time for a gated equilibrium study is at least 10 times that of an initial-transit study.
C. Both techniques require the same radiopharmaceuticals.
D. Both techniques require a bolus injection.
DISCUSSION: Both techniques are equally accurate for measuring left ventricular ejection fraction. The left ventricular imaging time for gated equilibrium studies is at least 10 times that of initial-transit radionuclide angiocardiography. Initial-transit techniques use data from fewer than 10 heartbeats, whereas equilibrium studies require more than 100 heartbeats to acquire data with similar information density. The initial-transit study can be performed with any radioactive substance, but the gated equilibrium technique requires a radiopharmaceutical that remains within the blood pool for imaging. The initial-transit radionuclide study requires a bolus injection, but an equilibrium study can be acquired up to several hours after injection and must be acquired while the tracer is at equilibrium.
A. Exercise ejection fraction.
B. Change in regional wall motion from rest to exercise.
C. Maximal cardiac output during exercise.
D. Change in heart rate during exercise.
DISCUSSION: The exercise ejection fraction is the single most important radionuclide variable relating to subsequent cardiac death or myocardial infarction, and this single variable contains 80% of the prognostic information in the test.
A. Ventricular aneurysms are commonly associated with systemic arterial embolization.
B. Absent collateral circulation in an area of myocardium supplied by an acutely occluded artery favors aneurysm formation.
C. Posterobasal aneurysms are more common than those located in the anteroapical region.
D. Aneurysm repair can improve associated cardiac valve dysfunction.
E. Persistent ST segment elevation after acute myocardial infarction suggests aneurysm formation.
DISCUSSION: The mural thrombus frequently present on the endocardial surface of an aneurysm is usually adherent and rarely embolizes. Collateral circulation, when present, often prevents transmural necrosis following arterial occlusion. Since the left anterior descending coronary artery is the vessel most commonly occluded in patients with ventricular aneurysms, most of the aneurysms are anteroapical. Improvements in ventricular contour and reduction in ventricular volume accompany aneurysm repair. Although persistent elevation of ST segments following myocardial infarction is very suggestive of aneurysm formation, the diagnosis should be confirmed by more definitive tests.
A. Class IV cardiac status.
B. Size of aneurysm.
C. Presence of left main coronary disease.
D. Emergent operation.
E. Location of aneurysm.
DISCUSSION: Class IV cardiac status and emergent operation both imply extensive myocardial damage and in most reported series are associated with increased operative mortality. Similarly, the presence of significant stenosis of the left main coronary artery increases the operative mortality of virtually all cardiac procedures. On the other hand, neither the size of the aneurysm nor its location affect early operative mortality, despite the fact that posterior aneurysms are technically more difficult to repair and are much less common.
B. Antiviral agents.
D. Gamma globulin.
DISCUSSION: Kawasaki's disease is a multisystemic disorder of unknown cause and is the leading cause of acquired heart disease in children in both Japan and the United States. Although many clinical aspects of Kawasaki's disease suggest an infectious agent, the search for a single agent has been unsuccessful; neither antibacterials nor antivirals have a role in the therapy of Kawasaki's disease. The goal of initial therapy of Kawasaki's disease is the reduction of inflammation, including coronary and myocardial inflammation. After the diagnosis of Kawasaki's disease is secured, patients are treated with intravenous gamma globulin and large doses of aspirin. Gamma globulin, 2 gm. per kg., is administered as a single infusion over 12 hours. Treatment with intravenous immune globulin has been shown to decrease the duration of fever, to decrease the prevalence of cardiovascular complications, and to prevent the progression to giant coronary aneurysms. High-dose aspirin therapy contributes to the resolution of the acute manifestations of Kawasaki's disease. When Kawasaki's disease is diagnosed, children are given a regimen of aspirin, 100 mg. per kg. per day, which is continued until defervescence. Thereafter, they are maintained on small doses of aspirin, 3 to 5 mg. per kg. per day, for 8 weeks. The goal of aspirin therapy is amelioration of symptoms and prevention of the thrombotic and embolic complications of Kawasaki's disease. Aspirin does not decrease the risk of the development of coronary aneurysms. There is no role for glucocorticoids in the treatment of Kawasaki's disease.
A. The presence of multiple coronary artery aneurysms.
B. Myocardial infarction and severe left ventricular dysfunction.
C. The presence of a 5 mm. aneurysm in the right coronary artery.
D. Progressive stenosis in the left anterior descending coronary artery.
E. None of the above.
DISCUSSION: The indications for surgical treatment of Kawasaki's disease include: (1) progressively stenotic coronary lesions demonstrated on coronary arteriography, with no distal coronary aneurysms with stenosis; (2) localized aneurysm with significant stenosis in the left main coronary artery; (3) significant stenosis in two coronary arteries; (4) presence of collateral vessels arising from a coronary artery with a proximal aneurysm; (5) progressive stenosis in the left anterior descending coronary artery; and (6) presence of a left ventricular aneurysm. Advanced thrombosis of coronary aneurysms causing critical stenoses in multiple coronary arteries is the most common indication for surgical intervention.
A. The tricuspid valve is usually insufficient.
B. Typically there is a left-to-right shunt across the ASD.
C. The redundant anterior leaflet of the tricuspid valve may cause obstruction of the right ventricular outflow tract.
D. Pulmonary hypertension is a common late complication.
E. High pulmonary vascular resistance in neonates exacerbates tricuspid regurgitation and cyanosis.
DISCUSSION: Ebstein's anomaly is characterized by downward displacement of the tricuspid valve into the right ventricular cavity. The anterior leaflet is large and “sail-like,” while the other two leaflets are rudimentary. Although the tricuspid valve occasionally may be stenotic, it is usually regurgitant. The tricuspid regurgitation and functional right ventricular outflow tract obstruction caused by the large anterior leaflet lead to right-to-left shunting across the ASD. Systemic venous hypertension is often present, but pulmonary hypertension almost never occurs with this malformation. Finally, neonates that present with Ebstein's anomaly are markedly cyanotic, owing to their high pulmonary vascular resistance. This causes a functional pulmonary atresia, which increases right-to-left shunting across the ASD.
A. In neonates, the tricuspid valve orifice may be oversewn and a systemic-pulmonary shunt created to provide pulmonary blood flow.
B. Techniques in repair of the tricuspid valve do not utilize plication of the atrialized right ventricle.
C. Closure of the ASD alone is adequate repair of the malformation.
D. If tricuspid valve replacement is performed, the valve should be sutured above the coronary sinus to avoid injury to the conduction system.
E. Currently, mechanical prostheses are recommended for tricuspid valve replacement because the durability of bioprosthetic valves in the tricuspid position is so poor.
DISCUSSION: In a recent report on the surgical treatment of Ebstein's anomaly in neonates, Starnes described a technique consisting of oversewing the tricuspid valve, atrial septectomy, and placement of a systemic-pulmonary shunt. These patients are then later staged to a modified Fontan procedure when they outgrow their shunts. Repair of the ASD alone was performed early in the treatment of Ebstein's anomaly and was associated with high mortality rates. It is not considered an adequate repair. Most techniques in tricuspid valve repair for Ebstein's malformation utilize plication of the atrialized right ventricle in addition to excision of redundant atrial tissue. If tricuspid valve replacement is necessary, current approaches utilize bioprosthetic valves because of their excellent durability in the tricuspid position. Placement of the valve ring above the coronary sinus has been associated with a lower rate of postoperative heart block.
A. Origin of the left coronary artery from the pulmonary artery.
B. Origin of the right coronary artery from the pulmonary artery.
C. Coronary artery fistula.
D. Membranous obstruction of the ostium of the left main coronary artery.
DISCUSSION: The major clinical finding with a coronary artery fistula is a continuous murmur over the site of the abnormal communication. This murmur may closely resemble that of PDA.
A. Coronary artery fistula.
B. Origin of the left coronary artery from the pulmonary artery.
C. Origin of the right coronary artery from the pulmonary artery.
D. Congenital coronary aneurysm.
DISCUSSION: The prognosis for most patients with origin of the left coronary artery from the pulmonary artery is poor. It has been estimated that 95% of patients with this anomaly die within the first year of life unless surgical therapy is undertaken. Patients whose right coronary artery originates from the pulmonary artery are usually asymptomatic. Patients with coronary fistulas occasionally suffer congestive heart failure early. Congenital aneurysms of the coronary arteries are most often asymptomatic until complications occur, usually later in life.
B. Congenital coronary artery fistula.
C. Membranous obstruction of the ostium of the left main coronary artery.
D. Congenital origin of the right coronary artery from the pulmonary artery.
DISCUSSION: Clinical manifestations of congenital origin of the right coronary artery from the pulmonary artery are usually minimal or absent. This malformation is thought to have been associated with death. The oldest reported patient with this malformation died at age 90 years from unrelated problems.
B. Congestive heart failure.
D. Transvalvar gradient of 35 mm. Hg without symptoms.
DISCUSSION: With progressive narrowing of the aortic valve area from the normal 3 to 4 sq. cm. to 1 sq. cm., patients become symptomatic. The classic symptoms produced by aortic stenosis are syncope, congestive heart failure, and angina. Once symptoms occur, life expectancy is limited to 2 to 5 years. Therefore, symptomatic aortic stenosis is an indication for aortic valve replacement. The risk of death with asymptomatic aortic stenosis is quite low, and aortic valve replacement is not indicated for asymptomatic patients with a transvalvar gradient less than 50 mm. Hg.
A. Moderate aortic insufficiency seen on echocardiography with normal left ventricular end-systolic dimensions.
B. Moderate to severe aortic insufficiency seen on echocardiography with cardiomegaly on chest roentgenography.
C. Moderate aortic insufficiency seen on echocardiography with symptoms of congestive heart failure.
D. Moderate aortic insufficiency with an end-systolic left ventricular dimension of 70 mm. as seen on echocardiography.
DISCUSSION: The left ventricle is usually able to compensate for a long time for the increased volume load imposed by aortic insufficiency. The natural history of asymptomatic aortic stenosis is excellent; 10-year survival for moderate aortic insufficiency managed medically is as high as 85% to 95%. Medical management typically consists of diuretics and afterload reduction; however, once the compensatory mechanisms begin to fail, survival is limited. Half of patients with signs or symptoms of congestive heart failure die within 2 years. Therefore, evidence of left ventricular dilation by echocardiography (left ventricular end-systolic dimension greater than 55 mm., cardiomegaly on chest roentgenography) or symptoms of congestive heart failure are indications for aortic valve replacement.
A. Systemic embolization.
B. Infective endocarditis.
C. Onset of atrial fibrillation.
D. Worsening pulmonary hypertension.
DISCUSSION: Although each is only a relative indication for operation for mitral stenosis, systemic embolization, infective endocarditis, onset of atrial fibrillation, and worsening pulmonary hypertension may each be an indication for operation for mitral stenosis. Systemic embolization, infective endocarditis, and onset of atrial fibrillation are each complications of mitral stenosis that portend a risk of further complication with continued medical therapy. Patients older than 40 years with mild class II congestive heart failure stand to gain symptomatically from operation for significant mitral stenosis and do not run excessive risk of multiple reoperative procedures.
A. Operation improves survival in patients with severe, symptomatic mitral valve disease.
B. Left ventricular dilatation with class I or class II heart failure is an indication for operation with mitral regurgitation.
C. Tricuspid regurgitation is most commonly caused by abnormalities of the leaflets themselves.
D. Mitral valve replacement requires resection of the mitral valve leaflets and chordae.
DISCUSSION: Relative to medical therapy alone, surgical therapy has been shown to improve survival in patients with severe, symptomatic mitral valve disease. In mitral regurgitation, left ventricular dilatation is an indication for surgical intervention regardless of failure symptoms. The most common cause of tricuspid regurgitation is tricuspid annular dilatation without abnormalities of the leaflets themselves. Mitral valve replacement with preservation of both leaflets or at least the posterior leaflet is well described and is probably advisable for most patients to preserve left ventricular function and reduce the probability of ventricular-annular separation.
A. Pulmonary edema.
B. Hepatic failure.
DISCUSSION: Hepatic failure and anasarca are indeed common symptoms of severe, long-standing tricuspid valve disease with increased venous pressure. Pulmonary edema is a consequence of left-sided heart disease and does not result from a tricuspid lesion. Similarly, hoarseness is most common after mitral valve disease with left atrial enlargement and is rarely due to tricuspid valve disease alone.
A. Extensive leaflet calcification.
B. Mitral regurgitation.
C. Chordal rupture of the anterior mitral leaflet.
D. Significant annular dilatation.
DISCUSSION: Extensive mitral valve calcification is a relative indication for mitral valve replacement. Mitral regurgitation or significant annular dilatation may, however, be amenable to mitral valve repair. Chordal rupture of the anterior leaflet is generally reparable using chordal transposition or polytetrafluoroethylene (PTFE) chordae.
A. Tricuspid regurgitation due to annular dilatation alone generally does not require valve replacement.
B. Mitral valve replacement with either a bioprosthesis or a mechanical valve requires warfarin anticoagulation.
C. Tricuspid valve replacement is generally an indication for using a tissue valve.
D. Chronic renal failure is a relative indication for tissue valves.
DISCUSSION: Tricuspid regurgitation due to annular dilatation alone generally can be treated with tricuspid annuloplasty or with correction of associated mitral valve disease. Mitral valve replacement with a mechanical valve does require warfarin anticoagulation; however, mitral valve replacement with a bioprosthesis may be managed with aspirin alone. Tricuspid valve replacement is an indication for using a tissue valve because of the significant incidence of valve thrombosis when a mechanical valve is in the tricuspid position. Chronic renal failure is a relative indication for tissue valves because valve calcification is rare and because anticoagulation of patients on dialysis carries high risks of morbidity and mortality.
A. Patient younger than 30 years.
B. Young female patient who desires children.
C. An elderly patient.
D. Tricuspid valve replacement.
DISCUSSION: Age younger than 30 years is a relative indication for mechanical valves because of an increased incidence of calcification of tissue valves in younger persons. A young female who desires children would be a relative contraindication to mechanical replacement because of the risk of teratogenesis and hemorrhage during pregnancy secondary to warfarin therapy. Advanced age is a relative indication for biologic valves to avoid complications of anticoagulation and because the probability of reoperation is low. Tricuspid valve replacement is a relative contraindication to mechanical valve replacement, owing to the increased incidence of tricuspid valve thrombosis with a mechanical prosthesis.
A. Bioprosthetic valves have a relatively high incidence of hemolysis.
B. Bioprosthetic valves have a lower incidence of postoperative prosthetic valve endocarditis.
C. Mechanical valves develop structural failure after an average of 7 to 10 years.
D. Mortality attributable to warfarin therapy approaches 5% per patient-year.
DISCUSSION: Bioprosthetic valves have a relatively low incidence of hemolysis. Bioprosthetic and mechanical valves do not differ significantly in the associated incidences of postoperative prosthetic valve endocarditis. Bioprosthetic valves develop structural failure after an average of 7 to 10 years, whereas mechanical valves have a life span of well beyond 10 years. The mortality attributable to warfarin therapy approaches 1% per patient-year.
A. Pulmonary hypertension.
B. Pulmonary edema.
C. Left ventricular dilatation.
D. An opening snap after the second heart sound.
DISCUSSION: Pure mitral stenosis without regurgitation may be associated with pulmonary hypertension, pulmonary edema, and an opening snap after the second heart sound. Left ventricular dilatation would be rare in pure mitral stenosis and generally occurs with volume or pressure overload of the left ventricle, as with mitral regurgitation.
A. Left free wall.
B. Right free wall.
C. Posterior septum.
D. Anterior septum.
DISCUSSION: All major published series of the Wolff-Parkinson-White syndrome indicate that the majority of all accessory pathways appear in the left free wall space. In one series, approximately 60% of all accessory pathways occur in the left free wall space. In Ebstein's anomaly, pathways are usually located in the posterior septum and/or right free wall spaces. If these patients are excluded, approximately 70% of pathways occur in the left free wall space.
A. Proximal antegrade block in the slow conduction pathway.
B. Proximal retrograde block in the slow conduction pathway.
C. Proximal antegrade block in the fast conduction pathway.
D. Proximal retrograde block in the fast conduction pathway.
DISCUSSION: A retrograde conduction block in either the slow or fast pathway would be likely to prevent a re-entrant circuit from developing. A proximal antegrade block in the slow conduction pathway is extremely unusual because of the short refractory period of the slow conduction pathway. The most common conduction block that occurs in patients with dual AV node physiology is a proximal antegrade conduction block in the fast pathway because of its longer refractory period. This antegrade block in the fast conduction pathway allows AV conduction to occur via the slow pathway and to return in retrograde fashion up the fast pathway to establish the re-entrant circuit responsible for AV node re-entry tachycardia.
A. His bundle ablation.
B. Left atrial isolation procedure.
C. Corridor procedure.
D. Maze procedure.
1. Patient's sensation of irregular heart rhythm.
2. Hemodynamic compromise because of loss of AV synchrony.
3. Increased vulnerability to thromboembolism.
Answer: A-1. B-1,2. C-1. D1,2,3
DISCUSSION: The surgical procedure most commonly employed for the treatment of atrial fibrillation is catheter ablation of the His bundle. The International Catheter Ablation Registry reveals that more than 60% of patients who undergo elective catheter ablation of the bundle of His do so for the treatment of atrial fibrillation. His bundle ablation is an isolation procedure, in that it confines the atrial fibrillation to the atria and protects the ventricles from the unpleasant sensation of an irregular heartbeat. Because the atria continue to fibrillate there is no restoration of AV synchrony, and therefore there is no improvement in cardiac hemodynamics. Moreover, the continuing fibrillation of the left atrium means that postoperatively the patient is still at the same risk for thromboembolism. Thus, His bundle ablation corrects only one of the three detrimental sequelae of atrial fibrillation, namely the arrhythmia problem.
The left atrial isolation procedure confines atrial fibrillation to the left atrium, allowing the sinus node to drive the remainder of the heart in a normal sinus rhythm. Thus, it alleviates the unpleasant sensation of an irregular heartbeat. In addition, because AV synchrony is re-established between the right atrium and right ventricle, right-sided cardiac output is restored to normal. This means that normal cardiac output is delivered through the lungs to the left side of the heart. In the presence of a normal left ventricle the left-sided cardiac output is also normal, despite the fact that left-sided AV synchrony is not present; however, because the left atrium is allowed to fibrillate, the vulnerability to thromboembolism remains unchanged postoperatively.
The corridor procedure allows the sinus node to drive the heart in normal sinus rhythm, but because of the total isolation of the sinoatrial and AV nodes from the remainder of the atria, the atria may continue to fibrillate. Even if they do not, in effect they are isolated from their respective ventricles so that AV synchrony is lost on both sides of the heart. As a result, the corridor procedure alleviates the sensation of arrhythmia but does not restore normal hemodynamics, nor does it decrease vulnerability to thromboembolism. The maze procedure ablates the re-entrant circuits responsible for atrial fibrillation and restores the normal sinus rhythm. Thus, it alleviates the sensation of arrhythmia, restores normal hemodynamics, and alleviates the vulnerability to thromboembolism.
A. They usually occur in the right ventricle.
B. They are usually associated with a left bundle branch block pattern during the tachycardia.
C. They are usually more refractory to medical therapy than ischemic ventricular tachyarrhythmias.
D. They usually occur as a result of automaticity rather than re-entry.
DISCUSSION: Nonischemic ventricular tachyarrhythmias usually occur in the right ventricle, and as a result the ECG shows a left bundle branch block–type pattern during ventricular tachycardia. These arrhythmias are notoriously refractory to medical therapy and they occur almost exclusively on a re-entrant basis.
A. This lesion, by site and histology, is the most common primary cardiac tumor.
B. It is best diagnosed by cardiac catheterization and angiography.
C. The symptom complex can mimic collagen vascular disease.
D. It has an intracavitary growth pattern.
E. It has a multicentric origin in the chamber wall.
DISCUSSION: Eighty per cent of primary cardiac tumors are benign, and half of these benign tumors are myxomas. Seventy-five per cent of myxomas arise in the left atrium in the region of the fossa ovalis. Echocardiography is the technique of choice in the evaluation of intracardiac tumors, and findings suggestive of myxoma occur in 95% of patients examined. Invasive procedures, with the attendant risk of tumor embolization, are not warranted. Owing to an autoimmune phenomenon, left atrial myxomas can present with systemic constitutional symptoms of fever, malaise, weight loss, polymyositis, and blood dyscrasias that mimic collagen vascular disease. Of surgical significance is the fact that most myxomas rarely extend deeper than the endocardium but grow as polypoid, intracavitary masses. Attachment by a vascular stalk thus allows tumor mobility, predisposing to embolization and interference with mitral valve competence and causing characteristic echocardiographic findings.
A. Sarcomas are the most frequent primary malignancy.
B. Metastatic tumors are usually asymptomatic.
C. Adjuvant chemotherapy and irradiation are efficacious in prolonging survival.
D. Intra-atrial extension of renal neoplasms is a contraindication for surgical resection.
E. Constrictive physiology is an indication for operation.
DISCUSSION: Twenty per cent of primary cardiac tumors are some variant of sarcoma. Precise histologic classification is not imperative, as all have a similar clinical picture with rapid systemic dissemination and aggressive local invasion. In contrast, metastatic tumors cause symptoms in only 10% of patients. Unfortunately, most primary and secondary cardiac malignancies infrequently respond to systemic chemotherapy or mediastinal irradiation. Surgical treatment is most successful with renal tumors extending into the right atrium. Significant 5-year survival can be achieved with concomitant nephrectomy and intra-atrial resection of the tumor thrombus. Relief of tamponade is worthwhile; however, extensive decortication provides little help.
A. Skin burns.
B. Painful chest wall muscle contractions.
C. Ventricular fibrillation.
D. Inability to pace.
DISCUSSION: In 1952 Zoll first described successful pacing through external metal electrodes applied to the anterior chest wall. Clinical experience with this technique has shown that it is both feasible and lifesaving for temporary pacing; however, disadvantages of the external pacing technique include skin burns when too little electrode jelly is applied, painful chest wall muscle contractions, and inability to pace in thick-chested or emphysematous patients. Ventricular fibrillation induced by external temporary cardiac pacing is exceedingly rare.
A. Ischemic heart disease.
B. Sclerodegenerative disease.
C. Traumatic injury.
DISCUSSION: Before permanent pacemakers were available, 50% of patients with complete heart block died within 1 year. The most common cause of acquired complete heart block in adults is sclerodegenerative disease of the cardiac skeleton and AV conduction system. Other less common causes of complete heart block include ischemic heart disease, cardiomyopathic processes, Chagas' disease, and traumatic injury.
A. Complete heart block.
B. Second-degree AV block.
C. Chronic bifascicular block.
D. Sick sinus syndrome.
DISCUSSION: Patients with sinus node dysfunction may develop a number of arrhythmias, such as inappropriate sinus bradycardia, chronotropic incompetence, sinoatrial exit block, and sinus arrest. This group of rhythm disorders typically occurs in older patients with or without underlying heart disease and is collectively known as the “sick sinus syndrome.” In addition, many patients with sick sinus syndrome have associated atrial tachyarrhythmias, particularly atrial fibrillation. This association of atrial tachyarrhythmias in patients with the sick sinus syndrome is called the tachycardia-bradycardia (or tachy-brady) syndrome. The most common indication for permanent pacing occurs in patients with the sick sinus syndrome.
A. Lower pacing thresholds.
B. Improved electrogram sensing.
C. Decreased battery life.
D. Less patient discomfort.
DISCUSSION: Decreasing pacemaker electrode tip size results in lower pacing thresholds, both at the time of implant and subsequently, because of higher current density. However, better sensing function is directly related to electrode area and is adversely affected by small electrode size. Therefore, a compromise between pacing and sensing efficiency is required. Typical electrode surface areas for pacing are between 8 and 10 sq. mm.
A. 10 to 100 ohms.
B. 125 to 250 ohms.
C. 300 to 800 ohms.
D. 1000 to 1500 ohms.
DISCUSSION: At the time of pacemaker implantation, in addition to measuring pulse amplitude (voltage and current) and pulse width, resistance is also determined. As described by Ohm's law, resistance is calculated by dividing voltage by current. Resistance calculations are made at a voltage near that of the pacemaker's output. The calculated resistance at 5 volts should range from 300 to 800 ohms. An unsatisfactorily low resistance is unsatisfactory because current is wasted and battery life is shortened. Conversely, excessively high resistance (more than 800 ohms) increases battery life but decreases the current delivered to the heart for pacing.
DISCUSSION: A ventricular inhibited-demand pacemaker using the ICHD code is designated as VVI. As the ICHD code states, the pacemaker senses intrinsic ventricular activity and is inhibited when this activity exceeds the standby or escape rate of the pacemaker. When the intrinsic ventricular rate falls below the escape rate of the pulse generator, the pacemaker begins to function at its programmed rate.
A. QT interval.
B. Venous blood temperature.
C. Mixed venous oxygen saturation.
D. Body motion.
DISCUSSION: During exertion, the required increase in cardiac output is obtained mostly by the increase in paced heart rate, although increased venous filling and maintenance of AV synchrony are also important contributors. The most commonly used physiologic parameters in rate-modulated pacemakers at the present time are body motion and minute ventilation. Other parameters that are less commonly used or under evaluation include QT interval, venous blood temperature, mixed venous oxygen saturation, contractility, stroke volume, venous pH, and the paced depolarization gradient.
DISCUSSION: “Universal,” or DDD, pacing has been shown to have many benefits over other pacing modalities, including the ability to track the intrinsic sinus rate, pace the atrium and ventricle, maintain atrioventricular synchrony, and avoid the pacemaker syndrome. Recognition of these benefits has steadily increased the use of DDD pacemakers in the last decade, and at the present time DDD is the most common pacing mode.
A. Anteromedial chest wall.
B. Anterolateral chest wall.
C. Inferomedial chest wall.
D. Inferolateral chest wall.
DISCUSSION: Bipolar impulse generators can be placed either in the subcutaneous tissue or beneath the muscle. Migration of the impulse generator most commonly occurs in infraclavicular pacemakers pockets. Migration tends to follow the curvature of the chest wall, and the impulse generator tends to migrate laterally. This can be prevented by creating an anteromedial pocket large enough to contain the impulse generator and lead. In susceptible persons the impulse generator can be further secured to the chest wall to prevent migration.
A. Pacemaker induction of atrial fibrillation.
B. Sensing of retrograde atrial activation.
C. Inappropriate ventricular sensing.
D. Lead fracture.
DISCUSSION: Pacemaker-mediated tachycardia occurs in the setting of intact ventriculoatrial conduction. Typically, premature ventricular contractions may be conducted retrogradely through the AV conduction system and cause retrograde activation of the atrium. If this retrograde atrial activation occurs after completion of the programmed pacemaker ventriculoatrial refractory period, the atrial event is sensed by the DDD pacemaker and evokes a paced ventricular event that may cause further VA conduction. If each ventricularly paced event results in atrial activation sensed by the pacemaker, pacemaker-mediated tachycardia will be generated.
DISCUSSION: Nifedipine is tolerated fairly well by elderly patients and is safe to use in the perioperative period with close hemodynamic monitoring. Atenolol is a safe beta-blocker to use during the perioperative period and provides protection from cardiac rhythm disturbances and rebound hypertension. Hydralazine, if given without a beta-blocker, often elicits reflex tachycardia, which limits its usefulness. Captopril is a safe agent that does not appear to interfere with the normal cardiovascular response to anesthesia, and abrupt withdrawal of this agent may result in severe hypertension and should be avoided. Reserpine is an adrenergic inhibitor that may depress cardiac output and result in hypotension, so its use in the perioperative setting is limited.
A. Digitalis compounds.
DISCUSSION: Dopamine and dobutamine stimulate cardiac beta-receptors and are very useful in providing inotropic support for patients in the postoperative period. Melrinone and amrinone are phosphodiesterase inhibitors that have strong inotropic effects while causing arterial and venous dilation. Melrinone and amrinone are useful in patients with low cardiac output, especially in the setting of congestive heart failure. Digitalis compounds can be troublesome in the postoperative period owing to the toxic effects of these agents. Furthermore, perioperative hypoxia and hypokalemia increase myocardial susceptibility to digitalis-induced ventricular arrhythmias.
A. Discontinuation of Coumadin therapy on the day of the operation.
B. Discontinuation of Coumadin therapy on the day of the operation with replacement of clotting factors with fresh frozen plasma (FFP) before the start of the surgical procedure.
C. Discontinuation of Coumadin therapy 5 days before operation with no further anticoagulation therapy before surgery.
D. Discontinuation of Coumadin therapy 5 days before operation with the institution of intravenous heparin as the prothrombin time normalizes.
E. Discontinuation of Coumadin therapy 2 days before operation followed by large doses of aspirin.
DISCUSSION: Many patients who require anticoagulation with Coumadin for underlying cardiac disease need to undergo routine general surgical procedures. The current recommendations for patients who have been on long-term Coumadin therapy is to discontinue Coumadin 5 days before an operative procedure. As the patient's prothrombin time normalizes intravenous heparin should be started. The patient should be maintained on a therapeutic dose of heparin with an activated partial thromboplastin time (aPTT) of at least 60 seconds. Heparin should then be withheld approximately 4 to 6 hours before the surgical procedure. The operation is then performed in a “heparin window,” where the level of anticoagulation can easily be titrated or totally reversed with protamine if necessary.
A. Aggressive use of inotropic support with epinephrine.
B. Aggressive diuresis with furosemide and inotropic support with dopamine.
C. Afterload reduction with nitroprusside and inotropic support with dopamine.
D. Close perioperative monitoring and inotropic support with melrinone.
E. Intravenous digitalis with diuresis using furosemide as needed.
DISCUSSION: Treatment of congestive heart failure using epinephrine alone is contraindicated owing to the profound vasoconstrictive properties of epinephrine, which only exacerbate the heart failure. Diuresis with furosemide and inotropic support with dopamine is acceptable for patients with mild congestive heart failure; however, in the postoperative period pharmacologic diuresis can lead to profound hypovolemia requiring continuous invasive hemodynamic monitoring. The ideal choice for the postoperative management of patients with severe congestive heart failure is afterload reduction using nitroprusside and inotropic support with dopamine. This helps to stimulate the failing heart while decreasing the afterload pressure against which the heart must pump. Melrinone is a useful phosphodiesterase inhibitor, which has been shown to be useful in the treatment of mild to moderate congestive heart failure. Digitalis along with a diuretic in the postoperative period can be troublesome owing to the potential toxicity of digitalis while the patient has ongoing fluid and electrolyte shifts.
A. Correction of electrolytes and blood chemistries.
B. Evaluation for possible myocardial infarction.
C. Treatment with intravenous lidocaine.
D. Attempt to limit the ventricular response with digitalis.
E. Immediate cardioversion.
DISCUSSION: When a patient develops postoperative atrial fibrillation following an extracardiac procedure, correction of the patient's blood chemistries and electrolytes is essential. The patient must also undergo evaluation for a possible myocardial infarction as the cause of the atrial dysrhythmia. The first rule in treatment is to slow the ventricular response and attempt to limit hemodynamic instability. Digitalis is effective in slowing down the ventricular response and thus improving the hemodynamic status of the patient. Lidocaine has little use in controlling atrial dysrhythmias but is very effective in decreasing ventricular ectopy. Immediate cardioversion is rarely indicated for new-onset atrial fibrillation. Only after correction of all underlying metabolic and electrolyte defects as well as an attempt at medical conversion and ventricular rate control is cardioversion recommended.
A. The coagulation cascade.
B. The fibrinolytic cascade.
C. Complement activation.
D. A and C.
E. A, B, and C.
DISCUSSION: Cardiopulmonary bypass stimulates a whole-body inflammatory response, and the concentrations of several inflammatory mediators (e.g., complement fraction C5a) have been associated with subsystem dysfunction following cardiopulmonary bypass. This inflammatory response is complex and has several arms, including the coagulation, fibrinolytic, and complement systems. Simply blocking one pathway is unlikely to completely prevent bypass-induced injury.
A. Systemic blood pressure of 90/50 mm. Hg.
B. Arterial PO 2 of 230 mm. Hg.
C. Mixed venous hemoglobin saturation of 78%.
D. Central venous pressure of 1 mm. Hg.
E. Plasma lactate value of 6 mg. per dl.
DISCUSSION: The purpose of cardiopulmonary bypass is to provide adequate circulation of blood to sustain aerobic metabolism. Oxygen consumption during bypass depends on bypass flow until a critical flow is attained. With higher flows there is no further increase in oxygen consumption (i.e., oxygen consumption becomes flow independent), and the mixed venous hemoglobin saturation increases. A mixed venous hemoglobin saturation of 78% indicates that bypass flow is above the critical level and that flow is adequate. The other variables do not ensure adequate bypass flow.
A. Interstitial fluid increases.
B. Blood flow becomes nonpulsatile.
C. Platelet count decreases.
D. Complement is activated.
E. Systemic vascular resistance falls.
DISCUSSION: Several events occur during the first few minutes of bypass. The tubing and oxygenator surfaces are coated by serum proteins that in turn activate platelets. This reduces the platelet count. The roller pump produces nonpulsatile flow, which is different from the usual pulsatile cardiac flow. Serum complement is activated by exposure of blood to the nonphysiologic surfaces of the pump-oxygenator, and systemic vascular resistance falls. Interstitial fluid accumulates during bypass; however, this occurs later during bypass.
A. Preload reduction.
B. Afterload reduction.
C. Coronary blood flow enhancement.
D. Decreased ventricular end-diastolic pressure.
DISCUSSION: In general, preload relates to the volume of blood or fluid presented to the left ventricle. Although wall tension does increase with increased volume, Starling properties are called forth for added efficiency. Preload is controlled by volume status as well as capacity of the venous system. The effects of balloon counterpulsation on cardiac preload are minimal and secondary to other changes. As the balloon collapses in the aorta, the absence of the balloon volume, or “abyss,” creates a decrease in ventricular afterload. In effect this decreases ventricular wall tension, reducing myocardial oxygen consumption significantly. During counterpulsation, the intra-aortic balloon inflates in diastole, elevating coronary perfusion pressure significantly. Maximal coronary artery perfusion occurs in this part of the cardiac cycle. Thus, ischemic ventricles benefit especially from balloon pumping. The balloon pump does not directly decrease the left ventricular end-diastolic pressure. However, in ventricles failing from ischemia the combination of afterload reduction and improved coronary blood flow usually augments cardiac function, producing decreased cardiac filling pressure or left ventricular end-diastolic pressure.
A. Medically refractory angina.
B. Acute papillary muscle rupture.
C. Left main coronary artery lesion.
D. Ventricular failure after cardiac surgery.
E. PTCA failure.
DISCUSSION: Medically refractory angina is one of the major indications for implementing the intra-aortic balloon pump. When intravenous nitroglycerin becomes ineffective at relieving chest pain or results in early hypotension, the balloon pump should be used in preparation for surgical revascularization or percutaneous angioplasty. By reducing left ventricular afterload, the pump reduces regurgitation into the left atrium. Thus, balloon counterpulsation is very helpful for treating patients with acute mitral insufficiency secondary to papillary muscle rupture. Patients should undergo valve surgical procedures emergently, as balloon pump support is only temporizing. The mere presence of a left main coronary lesion is not an indication for use of the balloon pump. In former years such pumps were inserted prophylactically before induction of anesthesia for coronary bypass surgery. Newer anesthetic techniques have largely obviated this; however, in the presence of a left main lesion and medically refractory angina the balloon pump should be used. The balloon pump is quite effective in helping to wean patients who have postcardiotomy left ventricular failure from cardiopulmonary bypass. This is one of the major uses of this device. The Emory University group was the first to expound on the efficacy of the balloon pump in stabilizing patients following percutaneous angioplasty failure. With the pump inserted, most patients can be transported to the operating room safely, many being stable enough to harvest an internal mammary graft instead of having to defer to the more accessible but less preferable saphenous vein.
B. Limb ischemia.
D. Aortic thrombosis.
DISCUSSION: Stroke rarely occurs secondary to intra-aortic balloon pump use. The balloon must be positioned well below the aortic arch vessels and never proximal to the left subclavian artery origin. Strokes have been reported from emboli being thrown retrograde from the balloon; however, this is very rare. Limb ischemia is one of the most frequent complications of balloon pumping. The combination of iliofemoral atherosclerosis and catheter luminal obstruction may impede distal flow. This may require catheter removal to re-establish flow. In 2% to 10% of patients, arterial reconstruction is necessary to repair balloon-related complications. Smaller catheters have helped prevent limb ischemia. Arrhythmias in general are not complications of balloon pumping. In fact, arrhythmias related to ischemia may be controlled by the balloon pump. Aortic thrombosis can occur very rarely with pump use. A more frequent occurrence is distal embolization with limb ischemia. Patients should be heparinized while the balloon catheter is in place. Following cardiac surgery heparinization is usually delayed for 12 to 24 hours.
A. Infrared sensor.
B. Inductive coupling.
C. Thermionic coupling.
D. High-pressure liquid chromatography (HPLC).
E. Infrared spectroscopy.
DISCUSSION: Electrical energy can be transmitted across the body wall by tunnelling an electric wire; however, experience has shown that infection, starting at the skin line and burrowing deeper into the body, will occur over time. This infection can be delayed, but not stopped, by the use of a velour covering on the wire. Wireless electrical energy transmission was first used in clinical surgery by W.W.L. Glenn in the 1950s for powering pacemakers. The remarkable advances in electronics have facilitated this technique; however, the placement of the two coils parallel to one another (with the skin between), as opposed to interlocking as in an industrial transformer, reduces the efficiency of transmission from approximately 99% to 70%.
A. It can support the circulation for over 1 year.
B. It may be complicated by infection or thromboembolism.
C. When further developed, it will be an ideal permanent heart substitute.
D. It is an ideal “bridge” for transplantation.
E. It can be implanted using techniques similar to those used for heart transplantation.
DISCUSSION: The pneumatic artificial heart was developed as a permanent cardiac substitute, but the need for two tubes to pass through the chest wall and the bulky power unit have relegated the pneumatic heart to short-term use as a bridge to transplantation. The heart is implanted using similar techniques as a heart transplantation. The presence of foreign surfaces and crevices make the device prone to thromboembolism and infection. Most surgeons feel that left ventricular support or biventricular assist pumps represent a better option for those patients with end-stage congestive heart failure who require use of a bridge device.
a. The most common form of the disorder is a double-inlet right ventricle
b. To be classified as a ventricle, the chamber must receive at least half of an inlet valve
c. This infant is a good candidate for a Blalock-Taussig shunt
d. Optimal correction of UVH diverts all vena caval blood flow into the pulmonary arteries (Fontan procedure)
e. In the absence of pulmonic stenosis, UVH usually presents as congestive heart failure
Answer: b, c, d, e
Univentricular heart is defined by the connection of the atria to only one ventricular chamber, usually the left as a double inlet left ventricle. A chamber must receive at least half of an inlet valve to be considered a ventricle. The presentation of UVH depends on the pulmonary blood flow; if pulmonary stenosis is present there is increased cyanosis and the infant is a candidate for a Blalock-Taussig shunt. In the absence of pulmonic stenosis, pulmonary flow is excessive and the presentation is congestive heart failure. Optimal correction of UVH diverts all vena caval flow into the pulmonary arteries as the Fontan procedure.
a. The most common associated abnormality is a bicuspid aortic valve
b. Chest radiograph is likely to show rib notching
c. The etiology is felt to be secondary to an inflammatory aortitis
d. In infancy, coarctation may present with a pink upper body and cyanotic lower body
e. “Paradoxical hypertension” seen after operative repair indicates residual stenosis from incomplete correction
Answer: a, b, d
Coarctation of the aorta occurs just distal to the origin of the left subclavian artery and results from contraction of ectopic tissue from the ductus arteriosus. The most common associated abnormality is a bicuspid aortic valve. Extensive collateral development involves the mammary and intercostal arteries producing rib notching on the chest radiograph. In infancy, flow to the lower body is from the ductus arteriosus before it closes, producing differential cyanosis. The “paradoxical hypertension” seen postoperatively is thought to relate to sympathetic nerve stimulation and does not reflect an incomplete repair.
a. Transseptal puncture should be used for definitive diagnosis
b. If this is a primary cardiac tumor it is most likely to be malignant
c. If this is a myxoma attached to the atrial septum, the adjacent septum should be removed with it
d. In infancy, the most common cardiac tumor is a rhabdomyosarcoma
e. The most common primary malignant tumor of the heart is angiosarcoma
Answer: c, e
Primary cardiac tumors commonly arise in the left atrium and can present with dyspnea, syncope, congestive failure and systemic embolism. Transseptal puncture should not be used for diagnosis because of the risk of embolism. Most primary cardiac tumors are benign by a 3:1 ratio. The most common malignant tumor is the angiosarcoma. Myxoma is the most common benign tumor, but it can recur and the adjacent atrial septum should be resected with it. In infancy, the most common cardiac tumor is a rhabdomyoma.
a. Echocardiography alone is sufficient to confirm the diagnosis of Tetralogy of Fallot
b. Cyanotic spells may be appropriately treated by propranolol
c. The Blalock-Taussig shunt connects the right ventricle to the pulmonary artery
d. Increasing cyanotic spells is the most common indication for operation
e. Operative repair of right ventricular outflow obstruction is never extended across the pulmonic valve since intolerable pulmonary insufficiency would result
Answer: a, b, d
In this typical scenario for Tetralogy of Fallot, echocardiography can confirm the diagnosis with no need for cardiac catheterization. Cyanotic spells are treated by supplemental oxygen, sedation with morphine and a beta blocker such as propranolol. For palliative increase in pulmonary blood flow, the Blalock-Taussig shunt is utilized connecting the subclavian artery to the pulmonary artery. Increasing cyanosis and cyanotic spells are the most common indication for operative repair. To correct the right ventricular outflow obstruction in Tetralogy, a transannular patch may be required extending into the pulmonary artery. Fortunately the pulmonary valvar insufficiency that results is well tolerated in the absence of tricuspid insufficiency or ventricular dysfunction.
a. A systolic ejection click would signify that the stenosis is supravalvar
b. In the absence of cardiomegaly, cardiac catheterization to measure the pressure gradient is necessary
c. Development of syncope would suggest an intracranial lesion
d. In valvar aortic stenosis a pressure gradient of 80 mmHg is an indication for operative repair regardless of symptoms
e. In membranous subvalvar aortic stenosis a pressure gradient of 40 mmHg is an indication for operative repair
Answer: d, e
In the patient with findings of aortic stenosis, a systolic ejection click is evidence that the obstruction is valvular. Cardiac size does not provide an indication of the severity of the stenosis and is frequently normal. The development of angina or syncope reflects inadequate cardiac output and signifies late-stage disease. A pressure gradient over 75 mmHg is an indication for operation in valvar aortic stenosis even if the patient is asymptomatic while a lesser gradient of 30 mmHg or more is considered sufficient for operative correction of membranous subvalvar stenosis.
a. The most common cause of cyanosis this early is transposition of the great vessels (TGV)
b. If TGV is present, echocardiography will show that the posterior vessel leaving the left ventricle is a pulmonary artery
c. If TGV is confirmed by echocardiography, cardiac catheterization has little to add
d. The EKG is helpful in making the diagnosis of TGV since it shows reversed dominance of the ventricles
e. To improve mixing of pulmonary and systemic circulations, prostaglandin should be used to increase pulmonary vascular resistance
Answer: a, b
TGV is the most common cause of cyanosis in the first week of life, and this diagnosis can be confirmed by echocardiographic demonstration of a posterior pulmonary artery attached to the left ventricle. Cardiac catheterization is useful to confirm the anatomy, detect other lesions, define the coronary anatomy and improve cardiac mixing by balloon atrial septostomy. The EKG is not helpful in the diagnosis of TGV since it shows only normal right ventricular dominance. Prostaglandin improves the mixing of the circulation by opening the ductus arteriosus and reducing pulmonary vascular resistance.
a. Spontaneous closure of the VSD is rare
b. Location of the VSD has little effect on the degree of cyanosis
c. Double outlet left ventricles do not occur
d. Coincidental aortic stenosis with DORV is not compatible with life
e. Doubly committed VSD refers to its relationship to the great vessels
Answer: a, e
In DORV, the location of the VSD affects the direction of flow of oxygenated blood and thus determines the degree of cyanosis. Fortunately, the VSD rarely closes since that would result in severe decompensation or death. Double outlet left ventricles occur but are less common than DORV. A number of other anomalies are associated with DORV including both valvar and subvalvar pulmonary and aortic stenosis. The VSD may be directed to either or both great vessels (doubly committed) or remote from them (noncommitted).
a. Cardiac catheterization is indicated if the chest film shows cardiomegaly
b. Radiology report of “scimitar syndrome” findings on the chest film would indicate need for an arteriogram
c. If the catheterization report is “ostium secondum defect,” at least one pulmonary vein drains anomalously
d. Measured pulmonary vascular resistance of 14 Woods units/m2 with an ASD mandates early repair
e. An ASD with Qp/Qs of 1.8 can be observed until symptoms occur
The findings suggest an atrial septal defect (ASD) that can be confirmed by 2D echocardiography eliminating the need for cardiac catheterization. The ostium secondum type defect is most commonly found, but it is the sinus venosus type that is associated with anomalous pulmonary venous drainage. In the scimitar syndrome, the anomalous pulmonary vein can be seen on a chest radiograph and, since these are associated with a hypoplastic lung that is supplied by an anomalous systemic artery from the aorta, an arteriogram is appropriate. An ASD with a significant left-to-right shunt as demonstrated by a Qp/Qs ratio in excess of 1.5 should be repaired. When the pulmonary vascular resistance is elevated above 10–12 Woods units/m2 the patient is not a candidate for repair due to fixed pulmonary hypertension.
a. Ischemia is due to perfusion of the myocardium with inadequately oxygenated blood
b. Selective coronary angiography should not be attempted because of the risk of myocardial infarction
c. Conservative treatment is preferred to allow the coronary artery to grow to a size that will allow bypass construction
d. If the infant deteriorates, ligation of the coronary at its origin is a viable option
e. The severity of the abnormality insures that it will always be detected in the first year of life
Anomalous origin of the left coronary artery from the pulmonary artery results in reverse flow in the coronary into the low-pressure system as a steal from the coronary circulation. If collaterals from the right coronary develop to allow adequate myocardial perfusion, the disorder is frequently not diagnosed until later in life when a murmur is heard. Selective coronary arteriography is appropriate to define the anatomy and operative repair is undertaken promptly. Ligation of the anomalous coronary can be lifesaving but leaves the child dependent on a single vessel and coronary bypass is preferred.
a. Pulmonary artery banding
b. Urgent closure if a VSD is found on echocardiography
c. Medical treatment only with digitalis and diuretics
d. If a VSD is found, repair is unlikely to be possible because of elevated pulmonary vascular resistance
e. If a restrictive VSD is found, spontaneous closure is a possibility and operative repair should be delayed
Answer: c, e
Large VSDs present at 6–8 weeks of age when the normally elevated pulmonary vascular resistance falls, allowing an increase in the left-to-right shunt. Since roughly half of all VSDs undergo spontaneous closure, particularly with restrictive defects, the initial management is medical. The diagnosis is confirmed by echocardiography and cardiac catheterization. Advanced pulmonary vascular changes do not occur usually until 2 years of age and banding is only rarely indicated for palliation for multiple complex muscular VSDs.
a. The second heart sound will show fixed splitting
b. Despite diagnostic echocardiography, cardiac catheterization is indicated to assess pulmonary artery resistance
c. Pulmonary artery banding is indicated to limit pulmonary flow and allow the child to grow
d. AVSD is classified according to the morphology of the anterior leaflet of the common A-V valve
e. Operative repair is best performed after 2 years of age
Answer: a, b, d
AVSD is a defect of endocardial cushion development which produces morphologic abnormalities of both AV valves and both atrial and ventricular septa. It is usually classified according to the morphology of the anterior leaflet of the AV valve. The pulmonary vascular resistance remains elevated in infancy delaying diagnosis and producing fixed splitting of the second heart sound. Cardiac catheterization is indicated to assess pulmonary vascular resistance, but pulmonary artery banding is no longer performed to protect the pulmonary bed. Instead, operative repair is made, preferably before the age of 6 months.
a. If aortic insufficiency is detected, the defect is likely to be subpulmonic in location
b. Finding aortic stenosis in addition to the VSD would be highly unlikely
c. The cath data indicate a restrictive type of VSD
d. If pulmonary vascular resistance falls with tolazoline administration, it is safe to close the VSD
e. Operative closure of VSDs is possible without ventriculotomy
Answer: a, c, d, e
The finding of aortic insufficiency in a patient with VSD suggests prolapse of the aortic valve due to a subpulmonic or supracristal defect. Associated aortic stenosis, mitral stenosis and coarctation are common with VSDs. The finding of a moderate left-to-right shunt and a right ventricular pressure well below systemic levels indicates a restrictive VSD. If elevated pulmonary vascular resistance is found, the ability to respond to a vasodilator like tolazoline indicates that the resistance is not fixed and operative repair is possible. Operative repair of VSDs is frequently possible via atriotomy or through the pulmonary artery.
a. The most likely diagnosis is coarctation of the aorta
b. If large pulmonary arteries are noted, a patent ductus is likely
c. To discriminate between a and b, prostaglandin administration can be used which will constrict the patent ductus arteriosus
d. If a ductus if found, operative repair should be delayed until the respiratory symptoms improve to reduce mortality rates
e. Normal ductus closure depends on increased oxygen saturation in the pulmonary artery
Answer: b, e
A continuous “machinery” murmur is characteristic of patent ductus arteriosus typically seen in the premature infant. Normal closure of the ductus is prompted by a fall in pulmonary vascular resistance that increases the left-to right shunt and oxygen levels from the aorta. Indomethacin can cause ductus closure by cyclooxygenase inhibition which decreases endogenous prostaglandins. Prostaglandin infusion would keep the ductus open. Operative closure can be done safely in even the smallest neonates and usually promptly relieves the respiratory distress.
a. Natural history of this anomaly allows only 20% one-year survival
b. The most likely configuration of the truncal valve is bicuspid
c. Location of the pulmonary arteries minimizes the risk of pulmonary vascular obstructive disease (Eisenmengers)
d. Repair of the lesion requires an extracardiac conduit
e. Optimal timing of operative repair is at 6–12 months
Answer: a, d
The defect described is truncus arteriosus which carries an 80% one year mortality rate uncorrected. The truncal valve is most commonly tricuspid (65%) or quadricuspid (25%); least likely bicuspid (9%). The large left-to-right shunt makes these patients particularly likely to develop pulmonary vascular obstruction (Eisenmenger’s syndrome). Operative repair requires detachment of the pulmonary arteries which are reconnected to the right ventricle by an extracardiac conduit, and the optimal timing for repair is within the first 6 months of life.
a. Initial management should include prostaglandin infusion
b. Ventilatory adjustment should maintain PaCO2 at approximately 40 mmHg
c. Survival depends on sustained patency of the ductus arteriosus
d. Cardiac transplantation for HLHS requires inclusion of the donor aortic arch
e. Reconstruction for HLHS converts the pulmonary artery into the main outlet for a functional single ventricle (Norwood)
Answer: a, b, c, d, e
The neonate with HLHS has a severely underdeveloped left ventricular and aortic arch and is dependent on patency of the ductus which is facilitated by prostaglandin infusion. Ventilator adjustment to reduce supplemental oxygen and maintain PCO2 of 40 mmHg avoids excessive pulmonary flow. The options for treatment include cardiac transplantation which requires a donor aortic arch and reconstruction by the Norwood procedure which converts the pulmonary artery into the main outlet for a functional single ventricle.
a. Onset of angina indicates concomitant coronary artery disease independent of valvular lesion
b. Percutaneous aortic balloon valvuloplasty should be considered since it has generally favorable results
c. Patient is not an operative candidate since heart failure has not occurred
d. A measured transvalvular pressure gradiant > 50 mmHg would be an operative indication
The ventricular hypertrophy which accompanies aortic stenosis increases oxygen demand while mechanical forces increase resistance to perfusion, resulting in ischemia. Only one half of these patients with angina have coronary artery disease. Percutaneous balloon valvuloplasty of the aortic valve has high complication and recurrence rates. Any such patient with symptoms has an indication for operations as would the patient with a transvalvular gradiant > 50 mmHg.
a. Perperal vasdilators are contraindicated
b. The inta-aortic balloon pump can be used to improve cardiac output
c. Furosemide and nitroglycerin would be appropriate
d. Valve replacement is necessary
Answer: c, d
Peripheral vasodilators are key to the treatment of AI favoring peripheral blood flow. The intraaortic pump is contraindicated because diastolic augmentation worsens aortic regurgitation. Both furosemide and nitroglycerin would be of value to treat the failure, but the most effective treatment requires replacement of the valve.
a. Critical mitral stenosis is defined as an orifice area reduced to 2 cm2
b. With a fixed mitral orifice, the change from sinus rhythm to atrial fibrillation has little effect on cardiac output
c. Mural thrombi and thromboembolism are directly related to the presence of atrial fibrillation
d. Depressed cardiac output is usually due to depressed myocardial contractility
Normal adults have a 4–6 cm2 mitral orifice and reduction to 2 cm2 is mild stenosis while reduction to 1 cm2 is considered critical mitral stenosis. Even with a fixed orifice, the onset of atrial fibrillation reduces cardiac output by 20%. Mural thrombi and thromboembolism are directly related to the presence of atrial fibrillation. Mitral stenosis spares ventricular function, and the loss of cardiac output is from decreased preload.
a. Mitral stenosis is the most common lesion
b. Of all cardiac valves, the aortic is the most anterior
c. Stenosis is the most common lesion of the aortic valve
d. Rheumatic heart disease is the most common cause of valve dysfunction
Answer: c, d
Aortic valvular stenosis is the most common type of valvular lesion followed by mitral stenosis. Anatomically, the pulmonic valve is the most anterior of the cardiac valves. Rheumatic heart disease is the most common cause of valve dysfunction and the most common cause of multivalvular disease.
a. Chest radiograph will show cor bovinum
b. The apical murmur is due to the Gallavardin phenomenon
c. A carotid shudder would be expected
d. Abdominal exam will show a pulsatile liver
This patient with aortic insufficiency has a volume loading strain on the heart which produces cor bovinum as dramatic enlargement. The apical murmur produced by turbulence with mitral forward flow mimics mitral stenosis and is called an Austin-Glint murmur. A carotid shudder occurs with aortic stenosis and a pulsatile liver is typical of tricuspid insufficiency.
a. Severe heart failure is more likely from acute than chronic valvular dysfunction
b. Valvular dysfunction produces both volume and pressure afterload stress on the heart
c. Early cardiac dilation from valve dysfunction shifts the Frank-Starling curve to depress cardiac output
d. The LaPlace law predicts that wall stress decreases with increasing ventricular radius
Answer: a, b
Valvular dysfunction produces both volume and pressure overload representing afterload stress on the heart. Although cardiac reserves allow for gradual adaptation to chronic valvular dysfunction, acute dysfunction is less well tolerated and more likely to result in severe heart failure. The increase in diastolic filling which initially dilates the heart, shifts the Frank-Starling curve to improve ejection and cardiac output. The LaPlace law predicts that wall stress increases with increasing ventricular radius but is inversely related to wall thickness.
a. The organisms most likely responsible are gram-negative and fungal
b. The pulmonic valve is most likely to be affected
c. A negative echocardiogram is useful to exclude the diagnosis
d. Valve replacement is necessary if the native valve is excised to treat infection
The typical endocarditis in a drug-abuser involves fungal and gram-negative organisms which infect the tricuspid rather than the pulmonic valve. An echocardiogram is useful to confirm the presence of vegetations but it may overlook smaller ones so it cannot be used to exclude the diagnosis. Although valve replacement is usually preferable, the infected tricuspid valve can be excised without prosthetic replacement.
a. Oxygen and lidocaine should be administered prophylactically
b. If chest pain persists, IV nitroglycerin should be used to limit infarct size
c. Ca-channel blockers are also of value to limit infarct size
d. Morphine IV can be used but has no therapeutic effect
Initial treatment during an early evolving MI should include oxygen, but lidocaine should be used only if arrhythmias occur. Nitroglycerin IV is of value to limit infarct size but not Ca-channel blockers which have no such benefit. By decreasing pain and anxiety, morphine IV has a significant therapeutic effect in decreasing myocardial oxygen demand.
a. Under circumstances of increased oxygen demand by the myocardium, O2 extraction from arterial blood can increase
b. Coronary flow is maximal during systole
c. Adenosine is the most important metabolic regulator of coronary blood flow
d. Sympathetic nerve stimulation constricts coronary arteries despite the need for increased cardiac output
Answer: c, d
Since myocardium maximally extracts O2 from blood at rest, increased demand requires increased delivery. Systolic pressures compress intramyocardial vessels, so maximal coronary flow is during diastole. Adenosine, a breakdown product of ATP, is a vasodilator and the most important metabolic regulator of coronary blood flow. Although sympathetic nerves produce coronary vasoconstriction, the autoregulatory vasodilatory responses to increased myocardial demand overwhelm that effect.
a. In 80%–85% of cases the posterior descending coronary artery (PDA) arises from the circumflex coronary artery
b. The PDA gives off the AV nodal artery
c. The great cardiac vein ascends along the right coronary artery to empty into the coronary sinus
d. Thebesian veins drain from only left and right ventricles
In 80%–85% of cases the circumflex coronary artery ends with branches to the left ventricle while the PDA originates from the right coronary in 80%–85% of cases. The PDA gives off the AV nodal artery and its occlusion can result in heart block. The great cardiac vein ascends along the left anterior descending coronary artery and the Thebesian veins drain all 4 chambers.
a. Nitroglycerin primarily dilates coronary arterioles
b. b-blocking agents act to reduce myocardial O2 demand
c. Ca-channel blocking agents reduce ventricular contractility
d. Ca-channel agents should not be used if there is an element of coronary vasospastic disease
Answer: b, c
Nitroglycerin primarily dilates venous capacitance vessels, but at higher doses can produce coronary and systemic arterial dilation. b-adrenergic blocking agents reduce myocardial O2 demand by decreasing heart rate and contractility. Ca-channel blocking agents reduce ventricular contractility, produce vasodilation and may protect myocytes. They are particularly effective for coronary vasospastic disease.
a. The mortality rate for cardiogenic shock after acute MI is increased more than 10 fold in comparison to no shock
b. Age, ejection fraction, MI size and previous MI serve as predictors of cardiogenic shock
c. Acute loss of more than 20% of myocardium frequently results in cardiogenic shock and death
d. Emergency revascularization is contraindicated for the MI patient in cardiogenic shock
Answer: a, b
Cardiogenic shock is unusual after acute MI but increases the mortality rate from 4% to 65%. All of the risk factors described plus a history of diabetes mellitus can predict cardiogenic shock. The volume of myocardium lost acutely that is associated with shock is 40%. Recent studies suggest that emergency coronary bypass can be used within 18 hours of shock to reduce the mortality rate to 7%.
a. Thrombolytic therapy should be considered immediately since the benefit is greater the earlier it is given
b. Of the drugs available, recombinant tPA produces better results than SK or APSAC although it is more expensive
c. Thrombolytic therapy requires catheterization for intracoronary administration
d. Addition of heparin and antiplatelet drugs produces no incremental benefit
Thrombolytic therapy for acute MI is of significant value in reducing mortality with benefit related to early administration. Although rtPA can produce higher coronary patency rates, the results of treatment are no better than with SK or APSAC. Thrombolytic drugs were initially given intracoronary but can be used effectively when given systemically IV. There is an added benefit from heparin and antiplatelet drugs to prevent rethrombosis.
a. The electrocardiogram is most likely to show a prominent Q in lead 3 if this is an MI
b. If Q wave is present, the infarct is subendocardial rather than transmural
c. Creatine kinase measurement alone is diagnostic of MI
d. Since bradycardia rarely occurs with MI, another diagnosis should be considered
Pain is the most common complaint in patients with myocardial infarction although 20%–25% are asymptomatic. Inferior MIs involving the right coronary frequently have parasympathetic activity with bradycardia, hypotension and a prominent Q wave in lead 3. The presence of a Q wave indicates a transmural MI which can be confirmed by measurement of the specific isoenzyme for cardiac tissue (CK-MB) since creatine kinase can be elevated non-specifically after stroke or operation.
a. A long symmetric lesion in the left main coronary artery would be appropriate for PTCA
b. Multiple obstructive lesions in the same artery would be a contraindication to PTCA
c. A focal lesion in the left anterior descending coronary artery where the vessel is 1 mm in diameter would allow PTCA
d. Successful PTCA for a simple lesion carries a recurrent stenosis risk of less than 10%
The ideal lesion for PTCA is focal symmetric stenosis in an epicardial vessel. However, it is relatively contraindicated for significant disease in the left main coronary, for multiple obstructive lesions in the same artery, and for vessels less than 2 mm in diameter. Restenosis rates of 20% to 40% occur within the first 4–6 months after successful dilation for simple lesions.
a. Operative mortality in patients > 70 years is more than double that of younger patients
b. If the patient is a woman, the risk is higher than it would be for a man
c. A previous CABG procedure increases the complexity and complication rate, but does not alter mortality rate
d. Results are better if there is ischemic cardiomyopathy than if there is hibernating myocardium
Answer: a, b
Operative mortality for patients > 70 years was 8% in the CASS study as compared to 3% in younger patients. For reasons not entirely clear, the risk of CABG is higher in women than in men. Reoperative procedures carry a higher operative mortality due to technical difficulties, more advanced disease, and less complete revascularization. Congestive heart failure is a major determinant of poor surgical outcome, but the results are better when there is viable myocardium (hibernating) than when there is irreversible ischemic cardiomyopathy.
a. An intra-aortic balloon pump should be used and cardiac catheterization performed
b. If the infarct was posterior, this is most likely due to a ventricular septal defect
c. Pulmonary wedge pressure tracing of prominent V waves without an O2 step-up suggests papillary muscle rupture
d. Operative repair of a post MI VSD should be delayed to allow strengthening of the myocardium to hold sutures
Answer: a, c
Both ventricular septal defect (VSD) and ruptured papillary muscle occur from 3–5 days post-MI and should be managed by intra-aortic balloon pump, decreasing afterload and cardiac catheterization for diagnosis. A VSD is most likely in an elderly hypertensive female who has sustained an anterior transmural MI; posterior MIs typically lead to papillary muscle rupture which is diagnosed by prominent V waves on pulmonary wedge pressure tracing. Survival rate for both of these complications is improved by early rather than late repair.
a. All patients with typical anginal symptoms should have coronary arteriography
b. Atypical patients with borderline positive stress tests should have arteriography
c. Patients who require valve procedures do not require arteriography
d. Patients in refractory heart failure awaiting cardiac transplantation should have coronary arteriography
Patients with typical angina and ECG changes should have angiography only if they are refractory to medical management and/or a candidate for revascularization. Patients with atypical signs and symptoms should have angiography to confirm or exclude the diagnosis. Patients with valve disease and risk of coronary artery disease should have angiography but patients awaiting cardiac transplantation are not candidates for revascularization and do not require coronary angiography.
a. CABG is more effective than medical treatment for relieving angina and improving physical work capacity
b. In CABG for unstable angina, there is no difference in late outcome between stable and unstable cohorts
c. For CABG, the most common arterial graft is the left internal mammary artery
d. Long term patency is improved when arterial grafts are used but there is no difference in the early mortality rate
Answer: a, b, c
Randomized studies show that CABG is more effective than medical therapy for relieving angina, improving physical work capacity and improving overall quality of life. When CABG is used for unstable angina, the initial complication and mortality rates are higher than for stable angina, but the late outcomes are similar. Use of arterial grafts for CABG has increased with the left internal mammary artery used most commonly; when at least one mammary artery is used, the early mortality rate is improved.
a. Thyroid tests are included to rule out hyperthyroidism
b. Typically positive stress ECG would show elevated ST segments
c. Dipyridamole is a useful adjunct to thallium scanning as it increases coronary perfusion pressure
d. Persisting defects on thallium scan indicate reversible myocardial ischemia
Diagnostic studies for coronary artery disease should detect risk factors such as diabetes mellitus, hyperlipidemia and hyperthyroidism. The stress ECG typically shows downward sloping ST segment depression. Dipyridamole is a coronary artery vasodilator that reduces systemic and coronary perfusion pressures. The persisting thallium scan defect reflects irreversibly scarred myocardium.
a. Rethrombosis is most likely and thrombolytic therapy alone should be repeated
b. The problem could have been prevented by early elective catheterization and PTCA
c. Patient has an indication for catheterization and PTCA if single vessel disease is found
d. Findings of multivessel disease at catheterization would indicate need for operative bypasses
e. If operative bypass is deemed necessary, there should be a 30-day delay to allow myocardial healing
Answer: c, d
After thrombolytic therapy for acute MI, angina recurs in 30%–35% and is an indication for cardiac catheterization and mechanical intervention to prevent infarct extension. Prophylactic catheterization, however, has not been found to provide benefit. If the findings at catheterization show limited disease treatable by PTCA, then it should be performed. But if multivessel disease or unfavorable anatomy is found, operative bypass should be carried out early since results are best within 30 days of the MI.
a. An inotropic drug should be used initially to increase cardiac output
b. If low cardiac output persists despite optimal physiological and pharmacological support, a balloon pump (IABP) should be inserted
c. Decreased cardiac filling pressures suggest the possibility of cardiac tamponade
d. When IABP is used, the balloon is inflated during diastole
Answer: b, d
Initial efforts to improve cardiac output should include correction of poor oxygenation or acidosis and optimization of rhythm, preload and afterload before an inotropic agent is used. If low cardiac output persists despite physiological and pharmacological support, an IABP should be inserted. It improves coronary artery perfusion by counterpulsation during diastole. Cardiac tamponade is heralded by increased cardiac filling pressures, narrowed pulse pressure and pulsus paradoxus.
a. This is a rare event since less than 5% of patients with coronary artery disease (CAD) are asymptomatic with exercise
b. Such a patient could progress to heart failure from ischemic cardiomyopathy
c. Typical angina pectoris is promptly relieved by rest or relaxation
d. Dyspnea on exertion can represent an angina equivalent
Answer: b, c, d
As many as 25% of CAD patients found by exercise testing are asymptomatic. Progressive coronary obstruction in these patients can produce heart failure from ischemic cardiomyopathy. Typical angina is relieved promptly by rest or relaxation. Ischemic reductions in ventricular contractility and compliance can produce dyspnea on exertion as an angina equivalent.
a. Since a heart rate of 180/min should be tolerated at his age, the hypotension must have another cause
b. A vagal maneuver that breaks the tachycardia suggests atrial flutter as the etiology
c. Atrial overdrive pacing should be tried for paroxysmal atrial tachycardia (PAT)
d. Verapamil IV should be used for rate control
e. Cardioversion is preferred for patients on digoxin
Answer: c, d
A tachyarrhythmia over 150 beats/min can produce hypotension and myocardial ischemia and demands urgent therapy. Vagal maneuvers may break PAT but are not usually effective for atrial flutter or fibrillation. Atrial overdrive pacing should be attempted for PAT or atrial flutter. Verapamil is the most effective approach to rate control for supraventricular arrhythmias, but cardioversion of patients on digoxin should be undertaken cautiously since they are prone to ventricular tachycardia.
a. Direct current catheter endocardial ablation has a high likelihood of success.
b. If the arrhythmia is inducible at EP study, there is an indication for operative intervention.
c. A recent MI would be a contraindication to operation
d. Ventricular failure would be a contraindication to operation
e. Monomorphic ventricular tachycardia is least amenable to surgical resection.
Answer: b, c, d
After catheter ablation, only 25% of patients remain free of ventricular arrhythmia off of drug therapy. If the arrhythmia is inducible at EP study and the patient is an acceptable risk, with a myocardial scar he has an indication for operation. Both recent MI and ventricular failure are contraindications to operation. Monomorphic ventricular tachycardia is the arrhythmia most amenable to surgical resection.
a. The most likely cause of SCD is ventricular arrhythmia
b. There is 30–40% chance of recurrent SCD in one year
c. Empiric antiarrhythmic drug therapy improves survival
d. An inducible ventricular tachyarrhythmia at EP study carries a favorable prognosis
e. If a ventricular aneurysm is found with arrhythmia, aneurysm resection is adequate treatment
Answer: a, b
Ventricular arrhythmias cause 75% of SCD, while 25% are due to acute MI. There is a 30–40% chance of recurrent SCD in one year. An inducible ventricular tachyarrhythmia carries a poor prognosis with < 50% five year survival from SCD unless it can be abolished. Empiric antiarrhythmic drug therapy does not improve survival. Aneurysmectomy alone is not adequate therapy for arrhythmias associated with aneurysms since the arrhythmia usually originates in adjacent mechanically stressed myocardium.
a. There is no special conduction path from the sinoatrial (SA) to the atrioventricular (AV) node
b. The blood supply to the AV node is from the anterior descending coronary artery
c. The only normal muscular connection between atria and ventricles is the bundle of His
d. The aortomitral continuity is the only area where supraventricular accessory pathways cannot occur
e. The sinus node artery arises from the right or circumflex coronary artery
Answer: a, c, d, e
The SA node is located at the junction of the superior vena cava and the right atrial appendage and receives its blood supply from the right or circumflex coronary artery. There is no special conduction path between SA and AV nodes. The bundle of His is the only normal atrioventricular muscle connection but abnormal pathways can occur anywhere except the area known as the aortomitral continuity. The blood supply to the AV node is from the posterior descending coronary artery.
a. A physical or electrical stimulus causes sodium fast channels and calcium slow channels to open
b. During the effective refractory period, only the slow calcium channels are closed
c. Rapid repolarization follows potassium egress from the cell
d. Extracellular hypokalemia increases sodium channel size increasing automaticity
e. Catecholamines increase outward potassium flow from myocytes
Answer: a, c, d
Physical or electrical stimuli cause sodium fast channels and calcium slow channels to open. During the effective refractory period, both slow calcium channels and fast sodium channels are closed and the myocardium cannot be excited. Then potassium channels reopen, allowing potassium out, and rapid repolarization occurs. Extracellular hypokalemia increases transmembrane potassium gradient and sodium channel size increasing automaticity. Catecholamines decrease outward potassium flow from myocytes enhancing automaticity.
a. The goal of the EP study is either sustained or non-sustained ventricular tachycardia
b. Patients with less than 5 repetitive complexes in response to stimulation are considered noninducible
c. An induced reentry from ventricular stimulation is not necessarily pathological
d. Microreentry arrhythmias are typical after myocardial infarction
e. Macroreentry arrhythmias are typical of myocardial ischemia
Answer: a, b
For arrhythmias of ventricular origin, the EP study goal is either sustained or nonsustained ventricular tachycardia. Patients with less than five repetitive complexes in response to stimulation are considered noninducible. Ventricular reentry does not occur in normal myocardium, so all reentrant arrhythmias are pathological. Macroreentry arrhythmias are typical after myocardial infarction, while microreentry arrhythmias are typical of myocardial ischemia.
a. Electrophysiologic studies (EPS) will require catheters in or at the right atrium, His bundle, right ventricle and coronary sinus
b. Pacing for EPS uses stimuli twice the diastolic threshold
c. The anomalous conducting bundle (Kent) is found in the right free wall if the coronary sinus catheter records the earliest atrial activity during reciprocating tachycardia
d. If the atrial catheter records the earliest activity during tachycardia, the bundle of Kent is located in the left free wall
e. If neither left or right bundle-branch block prolong the VA interval, the anomalous bundle is in the septum
Answer: b, e
For supraventricular arrhythmias, EPS requires catheters placed in the right atrium and ventricle, coronary sinus and His bundle. A programmable stimulator is used for stimuli that are twice the diastolic threshold and 2 msec in duration. When the coronary sinus catheter records the earliest activity during reciprocating tachycardia, the bundle of Kent is in the left free wall while it is in the right free wall if the earliest activity is in the atrial catheter. When neither left or right bundle-branch block prolong the VA interval, the bundle is in the septum.
a. If her arrhythmia is ventricular tachycardia, she is not a candidate for an Automatic Implantable Cardiac Defibrillator (AICD) since it only recognizes fibrillation
b. If an AICD is appropriate, it offers a 50% improvement in mortality compared to drug therapy
c. Poor ventricular function is a contraindication to AICD implantation
d. AICD should not be used for patients awaiting cardiac transplantation
e. AICD can provide antitachycardia pacing as well as defibrillation
Answer: b, e
The AICD is capable of recognizing ventricular tachycardia as well as fibrillation and can provide antitachycardia pacing, low or high-energy defibrillation or some combination. It offers a 50% improvement in mortality with 95% freedom from SCD at 5 years after implantation. Neither poor ventricular function nor pending transplantation are contraindications to AICD implantation.
a. The pathophysiology of WPW is a single bundle of Kent
b. Dangerous ventricular responses in WPW are due to the shorter refractory period of the accessory pathway
c. Identification of the accessory pathway of WPW is an indication for its interruption
d. Approximately half of the patients who have successful division of accessory pathways demonstrate VA block postop
e. Both radiofrequency catheter and surgical ablation offer excellent results with low morbidity
Answer: b, d, e
The pathophysiology of WPW is the Kent bundle of which 10–20% are multiple rather than single. The shorter refractory periods permit rapid and dangerous ventricular responses to atrial flutter or fibrillation. In 0.25% of the population, accessory pathways of WPW can be identified, but in the absence of a history of SVT, they have a normal life expectancy. Approximately half the patients who have successful division of accessory pathways demonstrate VA block postop. Both radiofrequency catheter and surgical ablation offer excellent results with low morbidity and the catheter technique is less costly.
a. Membrane-stabilizing local anesthetics (Class 1) act via sodium channel blockage
b. Class 1 drugs also shorten the refractory period
c. b-blocking drugs (Class 2) block the sympathetic nervous system but not circulating catecholamines
d. Bretylium and other Class 3 drugs inhibit potassium influx into cells
e. Calcium channel blockers (Class 4) directly affect the SA and AV nodes
Answer: a, d, e
Class 1 drugs are local anesthetics that act via sodium channel blockade, and lengthen the refractory period. Class 2 b-blocking drugs inhibit both the sympathetic nervous system and circulating catecholamines. Class 3 drugs inhibit potassium influx into cells and Class 4 drugs affect slow channel-dependent pacemaker tissue (SA and AV nodes).