1. (A) A significant concern during the repair of membranous VSDs, particularly when performed on young infants, is damaging the AV node when suturing the patch in place. The AV node courses along the posterior-inferior rim of membranous VSDs. Damage to the node could result in high-grade AV block immediately or shortly after surgical repair. AV block is not a significant risk of secundum ASD repair.

2. (B) Many adults with congenital heart disease have had surgical creation of direct aorta to pulmonary artery communication, either via an ascending aorta to right pulmonary artery connection (Waterston shunt) or via a descending aorta to left pulmonary artery connection (Potts shunt). These techniques have since been abandoned, due to difficulty regulating the size of the shunt and a high rate of branch pulmonary stenosis. Inappropriately large surgical shunts carry a high risk of pulmonary hypertension and, ultimately, pulmonary vascular obstructive disease. Central shunts and modified BT shunts utilize synthetic shunts of specific size, allowing for more predictable shunt volume. Classic BT shunts (direct connection of the left or right subclavian artery to the ipsilateral branch pulmonary artery) were frequently complicated by shunt obstruction and are no longer performed. In the presence of severe pulmonary valve stenosis, the pulmonary vascular bed would be reasonably protected and not at risk of pulmonary vascular disease, even with late repair.

3. (E) Modern surgical repair of AVSDs has resulted in tremendous improvement in life expectancy and quality of life for children (and now adults) with Down syndrome. The need for late reoperation after complete AVSD repair is approximately 15% to 20%. While small residual atrial or ventricular shunts may persist after repair and right AV valve (tricuspid) regurgitation may be present, they are uncommon indications for reoperation. Unlike in partial AV septal defects, LVOT obstruction is an infrequent indication for reoperation among patients with complete AV canal defects. Left AV valve (mitral) regurgitation, on the other hand, is the most common reason for late reoperation.

4. (B) Intuitively, severe preoperative AV valve regurgitation predicts postoperative AV valve regurgitation. A cleft in the left AV valve is universal in AV canal defects and does not predict postoperative regurgitation. Left ventricular size and dysfunction may influence the degree of mitral regurgitation, but this association is not so strong.

5. (D) The Nakata index is commonly used to predict operability in patients with pulmonary atresia-VSD. Angiographic measurements of the central pulmonary arteries just proximal to the first lobar branches (and any MAPCAs that perfuse an entire pulmonary segment and can be unifocalized) are taken, and the cross-sectional area of each branch (π × radius²) is calculated. The sum of these areas is divided by body surface area:

The calculation for this patient is as follows:

Patients with a Nakata index >200 are generally considered good candidates for complete repair (including unifocalization, if necessary). Patients with an index <200 may be candidates as well, but are at higher risk of pulmonary hypertension and right heart failure. They may be better off without surgical intervention or with limited surgical palliation. For the patient in the scenario, RPA patch angioplasty or stent placement would be indicated as part of the repair.

6. (B) Postoperative heart block, ST segment changes, or ventricular dysfunction with regional wall motion abnormalities should raise concern of compromised coronary artery perfusion. This may result from mechanical compression or obstruction by a prosthetic valve, transection of a coronary artery, or tension and kinking with coronary artery reimplantation. The child in this vignette presents a history typical of coronary artery obstruction after a procedure (aortic valve replacement) that presents risk of the same. While definitive identification of the compromised artery requires angiography, the AV node is supplied by a branch of the right coronary artery in 90% of humans, making disruption of the RCA the most likely cause of AV node dysfunction in this patient.

7. (E) Pulmonary arteriovenous malformations occur commonly in patients following Fontan procedures. Dyspnea on exertion and orthostatic or exertional cyanosis in Fontan patients can occur due to right-to-left shunting at a widely patent fenestration or due to right-to-left shunting from pulmonary arteriovenous malformations. These most commonly occur in the basal region of the lung.

8. (A) The sinus node is located in the posterior right atrium along the superiolateral aspect of the superior vena cava. As a result, surgical disruption of this area may result in damage to the sinus node. Of the choices available, only the atrial switch procedure affects the posterior aspect of the right atrium. In the Mustard/Senning atrial switch operations, systemic venous return is directed across the atrial septum to the left-sided, subpulmonary ventricle. This is done by suturing a patch baffle along the posterior (sinus venosus) wall of the right atrium, in close proximity to the sinus node.

9. (B) Figure 15.1 demonstrates complete heart block. Right bundle branch block is common after VSD repair, but complete heart block is rare after isolated VSD repair. The addition of surgical resection of a subaortic membrane or ridge introduces a risk of left bundle branch block, which along with the right bundle branch block from the VSD repair would result in complete heart block. The other lesions listed are not typically associated with a risk of left bundle branch block.

10. (E) The role of the cardiologist in the operating room includes providing accurate echocardiographic description of cardiac anatomy, particularly the presence of shunts that may complicate cardiopulmonary bypass. In this scenario, the patient develops left heart distention after being placed on bypass, which suggests ongoing pulmonary venous return to the left atrium. This results from persistent pulmonary blood flow that is not accounted for in the bypass circuit. The most likely cause in this situation is a systemic to pulmonary shunt, such as aortopulmonary collateral arteries. If the aorta is not cross-clamped, significant aortic valve regurgitation may result in left ventricular distension, but this is less likely to be the case for this patient. The other options are important findings to note prior to bypass, but would not cause left heart distension. A persistent left SVC typically drains to the coronary sinus and would result in blood return to the right atrium.

11. (C) While the most common cause of reoperation in patients with partial AV canal defects is mitral valve regurgitation, LVOT obstruction is a common cause and much more common than in the complete form of AVSD. Shortness of breath, cardiomegaly, and increased pulmonary vascularity may be caused by mitral valve regurgitation or LVOT obstruction. However, the ejection-type systolic murmur that diminishes with Valsalva presented in this patient clearly suggests outflow tract obstruction as the underlying problem. Primary pulmonary hypertension is very rare in children, and one would expect to find diminished pulmonary vascularity on chest x-ray. Mitral stenosis may cause this patient’s symptoms, but it is a less common late finding after partial AV canal defect repair and not suggested by the other findings in the vignette. A residual ASD could cause this patient’s symptoms if it was large enough, but, again, LVOT obstruction is a more common postoperative complication.

12. (A) Figure 15.2 shows a parasternal long axis view of the left ventricular outflow tract. There is a posterior malalignment VSD, which narrows the LVOT. This type of VSD is commonly associated with aortic arch obstruction, either coarctation or interruption. Thus, surgical repair will likely involve aortic arch repair as well.

13. (A) Figure 15.3 demonstrates an anomalous left coronary artery originating from the pulmonary artery (ALCAPA). ALCAPA typically presents in the second or third month of life after pulmonary vascular resistance falls and the anomalous coronary artery loses perfusion pressure. Infants typically present with a dilated, poorly functioning left ventricle caused by myocardial ischemia. These children are at risk of ischemia and infarction of the mitral valve papillary muscles and resultant mitral valve regurgitation. The tricuspid valve papillary muscles are usually perfused by branches of the right coronary artery.

14. (B) Figure 15.4A,B shows a right lower pulmonary vein draining below the diaphragm to the right atrium-IVC junction. Scimitar syndrome is the eponym for this anomaly. Surgical repair typically depends on the proximity of the anomalous venous connection to the right atrium and the presence of an ASD. Typically, the anomalous connection is transected and the right veins are reimplanted, either into the right or into the left atrium. If implanted into the right atrium, the right pulmonary venous return is then directed across an ASD into the left atrium by a patch baffle. The most common complication of this type of repair is obstruction of pulmonary venous return.

15. (B) The development of pulmonary arteriovenous fistulae has been identified as a risk of the classic cavopulmonary anastomosis (Glenn). Subsequently, it has been found to relate to the absence of hepatic effluent blood in the pulmonary circulation. While this patient had bilateral modified (bidirectional) Glenn anastomoses, the absence of hepatic venous return within the pulmonary circulation (due to IVC interruption) results in a similar lack of the hepatic factor that would otherwise prevent the development of the pulmonary AV fistulae. When surgically feasible, incorporation of hepatic venous return into the pulmonary circulation often results in diminution of the fistulae.

16. (E) The questions being posed by this scenario are whether this patient is a candidate for a Fontan-type palliation and how should the operation be performed. This patient’s cardiac hemodynamics are favorable for single-ventricle palliation, specifically the PA pressure is low (mean 11 mm Hg) with a reasonable transpulmonary gradient (5 mm Hg). This is not surprising in the context of pulmonary stenosis, which protects the pulmonary vascular bed from systemic pressure. Infants presenting with single-ventricle physiology typically are repaired in a staged fashion, consisting of a BT shunt shortly after birth, Glenn anastomosis by 6 to 9 months, and Fontan completion in young childhood. As this child is 3 years old, there is no obvious need to perform a Glenn anastomosis prior to Fontan completion. The modified Fontan, using an extracardiac conduit or a lateral tunnel approach, is favored over a direct RA-to-PA anastomosis (classic Fontan).

17. (A) The chest x-ray in Figure 15.5 demonstrates an elevated right hemidiaphragm. The clinical scenario is consistent with paralysis of the right hemidiaphragm, likely a complication from her surgical repair. In the absence of respiratory distress or exercise limitation, treatment of this finding is not necessary. Her “comfortable” tachypnea should be well tolerated.

18. (C) The vignette above describes a neonate with single ventricle and inadequate pulmonary blood flow, as demonstrated by the child’s oxygen saturation and paucity of pulmonary vascularity. This may result from valvular stenosis or obstruction at the VSD (bulboventricular foramen). The initial palliation, therefore, should be directed at increasing pulmonary blood flow. This is best accomplished by stenting the ductus arteriosus or placing a modified BT shunt from the subclavian artery to the branch pulmonary artery. Balloon atrial septostomy may be necessary if the ASD is restrictive, a rare occurrence in tricuspid atresia and not suggested by this patient’s findings. Pulmonary artery banding would decrease pulmonary blood flow. A DKS anastomosis consists of a direct ascending aorta to MPA (end-to-side) anastomosis. This is used in single-ventricle situations where there is left ventricular outflow obstruction (subaortic stenosis, valvular stenosis/atresia, coarctation) and allows for retrograde perfusion of the coronary arteries via a reconstructed “neo-aortic” arch.

19. (E) A DKS anastomosis consists of a direct ascending aorta to MPA (end-to-side) anastomosis. This is used in single-ventricle situations where there is systemic outflow obstruction (subaortic stenosis, valvular stenosis/atresia, coarctation) and allows for retrograde perfusion of the coronary arteries via a reconstructed “neo-aortic” arch. After a DKS anastomosis, the native pulmonary valve functions as the “neo-aortic” valve. The neonate in the vignette has doubleinlet left ventricle (as shown in Figure 15.7) and—based on the clinical presentation of poor perfusion but adequate oxygenation—malposed great arteries. As such, the pulmonary artery arises from the left ventricle, and the aorta arises from the diminutive right ventricle. Thus, systemic outflow is dependent on the size of the VSD (bulboventricular foramen). This patient presents with increased Qp:Qs, as evidenced by a systemic saturation of 95% and signs of poor systemic perfusion and a harsh ejection-type murmur. This may result from a restrictive VSD, subvalvular aortic stenosis, or aortic valve stenosis. In this situation, a DKS anastomosis allows for adequate systemic output and coronary artery perfusion. A BT shunt placed at the same time provides a stable source of pulmonary blood flow once the MPA is separated from the PA branches. Surgical enlargement of the VSD risks damage to the cardiac conduction system causing rhythm disturbances and ventricular dysfunction. A BT shunt alone does not address the problem of systemic outflow obstruction. PA banding would not be indicated as the primary problem is inadequate systemic output, not excessive pulmonary blood flow.

20. (E) Pulmonary valve stenosis can be managed initially with percutaneous pulmonary balloon valvuloplasty or surgical valvotomy. Percutaneous valvuloplasty tends to produce better relief of stenosis, but patients are often left with a greater degree of regurgitation than the surgical approach. A good initial surgical outcome, as described in this patient, carries a low risk of need for future operation, probably not more than 5% over the next 10 years.

21. (E) The type of surgical intervention indicated depends on a patient’s age, hemodynamics, and underlying cardiac anatomy. The vignette describes a child with pulmonary atresia and intact ventricular septum. These patients may qualify for a two-ventricle repair with placement of a conduit from the right ventricle to the pulmonary arteries (which may be confluent or surgically unifocalized). If the right ventricle is not usable as a functional pumping chamber, either because of hypoplasia or because of coronary to RV fistulae, then the patient is not a candidate for complete repair and requires some form of palliation. This patient has a very diminutive RV, demonstrated by a tricuspid valve Z-score of -3.5. It has been shown that when the tricuspid annulus Z-score is less than -3, the outcome is very poor after attempted complete repair. As a result, this patient should undergo palliation. Her low pulmonary vascular resistance suggests that she is a good candidate for a Fontan operation. At 4 years of age, a complete Fontan can be performed as a single operation, rather than first performing a staged bidirectional cavopulmonary anastomosis.

22. (C) Patients with pulmonary atresia and intact ventricular septum may qualify for a two-ventricle-type repair. If the right ventricle is not usable as a functional pumping chamber, either because of hypoplasia or because of coronary to RV fistulae, then the patient is not a candidate for complete repair and requires some form of palliation. It has been shown that when the tricuspid annulus Z-score is less than -3, the outcome is very poor after attempted complete repair. Infants with a Z-score of -2 to -2.5 and a functional tricuspid valve may undergo placement of an RV to PA conduit. This patient has a small but usable RV, demonstrated by a tricuspid valve Z-score of -2.3 and the absence of coronary cameral fistulae (RV-dependent coronary circulation). Low oxygen saturation suggests that he is outgrowing his BT shunt and should have the next stage operation, in his case a two-ventricle complete repair. Transcatheter perforation and balloon dilation of the atretic (membranous) valve or surgical valvotomy/RVOT reconstruction would be the preferred treatment options in this scenario.

23. (B) The angiogram demonstrates a very small RV chamber with multiple sinusoids and coronary cameral fistulae. These fistulae are common in pulmonary atresia with intact ventricular septum, where the RV is severely hypoplastic. Decompression of the RV by transcatheter or surgical means (e.g., pulmonary valvotomy or placement of a conduit) may decrease coronary perfusion pressure and cause diffuse myocardial ischemia. This patient should continue down a single-ventricle palliation pathway, with ductal stenting or placement of a modified BT shunt as the first stage.