Luc M. Beauchesne, MD, FACC

1. Which patients with adult congenital heart disease require antibiotic prophylaxis?

    The indications for antibiotic prophylaxis for endocarditis changed in 2007 with the new American Heart Association guidelines. A more restricted use of antibiotic prophylaxis in congenital heart disease is proposed, with increased emphasis on oral health. Prophylaxis is now suggested only in the following circumstances:

The new guidelines have also eliminated indications for prophylaxis for genitourinary (GU) or gastrointestinal (GI) procedures. (See also Chapter 33 on endocarditis and endocarditis prophylaxis).

2. What are the three main types of atrial septal defects (ASDs), and what are their associated anomalies?

    The three main types of ASDs are secundum (70%), primum (20%), and sinus venosus (10%). The secundum ASD is a defect involving the floor of the fossa ovalis of the atrial septum. It usually presents as an isolated anomaly. The primum ASD is a defect at the base of the atrial septum adjacent to the atrioventricular valves. It is invariably part of an atrioventricular septal defect (endocardial cushion defect), and a cleft mitral valve is almost always present. The sinus venosus ASD is a defect of the posterior part of the septum, usually located in the superior part. In the majority of cases, a sinus venosus ASD is associated with anomalous connections or drainage of the right-sided pulmonary veins (Fig. 45-1).

3. When should an ASD be closed? Which ASDs cannot be closed by a percutaneous device?

    ASDs vary in size. If the ASD is large enough, the associated left to right shunt will lead to right-sided volume overload and pulmonary overcirculation. Chronic right-sided volume overload leads to pulmonary hypertension, right ventricular dysfunction, tricuspid regurgitation, and right atrial dilation. Patients with ASDs also often develop atrial arrhythmias. Hemodynamically significant ASDs are usually 10 mm or larger, have a shunt ratio greater than 1.5, and are associated with right ventricular enlargement on imaging. It is recommended that only hemodynamically significant ASDs be closed. Most secundum ASDs can be closed percutaneously. Primum and sinus venosus ASDs cannot be closed percutaneously and require surgical closure.

4. List the four types of ventricular septal defects (VSDs).

    Different classifications for VSDs have been used; one common approach divides VSDs into four types:

5. What are the long-term complications of a small VSD in the adult patient?

    In the adult, there are two groups of patients with unrepaired VSD. The smallest group consists of patients with a large VSD that has been complicated by severe pulmonary hypertension (Eisenmenger syndrome). However, the vast majority of adult patients with VSDs have small defects that are hemodynamically insignificant (i.e., do not cause left ventricular dilation or pulmonary hypertension). As a rule these patients have a benign natural history. Rarely, some patients develop complications such as endocarditis, atrial arrhythmias, tricuspid regurgitation, aortic regurgitation, and double-chamber right ventricle.

6. What are the complications of a bicuspid aortic valve?

    A bicuspid aortic valve is present in 0.5% to 1% of the population. The main complications are progressive aortic stenosis, aortic regurgitation, or a combination of both. Other complications include endocarditis and aortopathy. Although infrequent (<10%), aortic coarctation is also a well-described association and must be ruled out in these patients. Patients in whom the bicuspid valve demonstrates signs of valve degeneration on echocardiography are at an increased risk of cardiovascular events and need close regular follow-up.

7. How is hemodynamic severity of coarctation of the aorta assessed in the adult patient?

    In coarctation of the aorta, the narrowing is typically in the proximal portion of the descending aorta, just distal to the left subclavian artery. Adult patients can be divided into two groups: those with native (i.e., unrepaired) coarctation and those who are postrepair (some of which have residual stenosis). Some coarctations are mild and not hemodynamically significant. Findings suggestive of a hemodynamically significant coarctation include small luminal diameter (less than 10 mm or less than 50% of reference normal descending aorta at the diaphragm), presence of collaterals, and elevated gradient (more than 20 mm Hg clinically, by catheterization, or by echocardiogram). The clinical gradient can be measured by comparing the highest arm systolic pressure (left or right) to the systolic pressure in the leg (typically measured by palpation of the pedal pulses while inflating a cuff at the calf level). Patients with hemodynamically significant coarctations are at risk of a number of complications, including refractory hypertension, accelerated atherosclerosis, cerebrovascular disease, and aortopathy.

8. In coarctation of the aorta in the adult patient, when should percutaneous stenting be considered?

    Most clinicians think that adult patients with hemodynamically significant coarctation of the aorta should be considered for intervention. Although surgery has been available for several decades, percutaneous dilation with stenting has evolved as an alternative. In the adult patient with residual stenosis after repair, stenting has become the first-line therapy at most centers. For adults with native coarctation, stenting has also become first-line therapy at many centers. In patients who undergo percutaneous stenting, the anatomy needs to be suitable (i.e., no significant arch hypoplasia). In adult patients who undergo surgery, the usual procedure is placement of an interposition graft which is done through a left-sided thoracotomy approach.

9. Which adult patients with patent ductus arteriosus (PDA) require percutaneous device closure?

    A PDA connects the proximal part of the left pulmonary artery to the proximal descending aorta, just distal to the left subclavian artery. The unrepaired ductus in an adult is usually small in diameter and the resultant left to right shunt is hemodynamically insignificant. However, in some patients the ductus diameter is large and results in severe pulmonary hypertension (Eisenmenger syndrome) if not repaired in childhood. Occasionally, some adults have moderate-size ducts resulting in shunting that is not hemodynamically negligible, but not significant enough to cause severe pulmonary hypertension. In these patients the left ventricle will be dilated and the pulmonary pressure may be mildly elevated. Clinically they will have a continuous murmur, a large pulse pressure, and signs of ventricular dilation. This latter group should undergo percutaneous closure in an attempt to prevent long-term complications. Although controversial, some centers advocate routine closure of small PDAs to prevent endarteritis.

10. How is Marfan syndrome diagnosed?

    The criteria for the diagnosis of Marfan syndrome have evolved over the years. The latest iteration was published in 2010 and has put more emphasis on gene testing, presence of aortic dilation, and abnormalities of the corneal lens. The main role of the cardiologist is to carefully assess the patient for aortic abnormalities. This usually consists of performing an echocardiogram and an MRI of the aorta. Patients with suspected Marfan syndrome should be referred to a geneticist, as the clinical phenotype overlaps with multiple other systemic disorders and the role of genetic testing is continuously evolving.

11. When should Marfan patients with aortic root dilation be referred for surgery?

    Although any part of the aorta can be involved in Marfan syndrome, the root is usually affected. Surgery (for root dilation) is done to prevent aortic dissection or rupture and is generally recommended when the aortic diameter is 50 mm or more. For patients with rapid progression (more than 5 mm/year) or a family history of dissection, intervention is recommended by some specialists at 45 mm or more. Traditionally, a Bentall procedure was performed in which the native aortic valve and root were replaced with a composite conduit (a tube graft attached to a prosthetic valve). If technically possible, the preferred first-line approach now consists of a valve-sparing procedure (David procedure) in which the root is replaced by a prosthetic conduit and the native valve is kept in place.

12. What is tetralogy of Fallot, and what is the main complication seen in the adult?

    Tetralogy of Fallot (TOF) consists of four features: right ventricular outflow tract (RVOT) obstruction, a large VSD, an overriding ascending aorta, and right ventricular hypertrophy. The RVOT obstruction is the clinically important lesion and may be subvalvular, valvular, or supravalvular, or may be at multiple levels. Repair, done in infancy, involves closing the VSD and relieving the RVOT obstruction. In many patients, to relieve the RVOT obstruction, surgery on the pulmonary annulus and valve leaflets is required and is usually complicated by severe residual pulmonary insufficiency. In the adult, over time, chronic severe pulmonary insufficiency often leads to right ventricular dysfunction and exercise intolerance, for which a pulmonary valve replacement (PVR) may be necessary. When PVR is performed, a tissue prosthesis is usually placed (homograft, porcine, or bovine prosthesis). The problem with tissue prostheses in young adults is that they require replacement at 10- to 15-year intervals. A percutaneous pulmonary valve prosthesis approach is increasingly being used to manage these patients with severe pulmonary insufficiency. Other complications in TOF include residual RVOT obstruction, residual VSD leak, right ventricular dysfunction, aortic root dilation, and arrhythmias.

13. What are the three Ds of Ebstein anomaly?

    Ebstein anomaly is characterized by an apically displaced tricuspid valve that is dysplastic, with a right ventricle that may be dysfunctional. The displacement affects predominantly the septal and posterior leaflets of the valve. The leaflets are usually diminutive and tethered to the ventricular wall. Typically, the anterior leaflet is unusually elongated. The right ventricle is often thin and can have both diastolic and systolic dysfunction. Half of patients have an interatrial communication, either patent foramen ovale (PFO) or ASD. Fifteen percent of patients have accessory pathways, which will manifest clinically as Wolf-Parkinson-White syndrome. The primary complication of Ebstein anomaly is tricuspid regurgitation and right-sided heart failure. If significant enough, placement of a tissue prosthesis or valve repair (if the valve anatomy is suitable) is indicated.

14. What drug therapy should now be considered in all patients with Eisenmenger syndrome?

    Eisenmenger syndrome refers to markedly elevated pulmonary pressures caused by a longstanding left to right shunt between the systemic and pulmonary artery circulations because of a congenital defect. Initially, left to right shunting leads to increased pulmonary vascular flow, which over time induces changes in the pulmonary vasculature leading to increased pulmonary vascular resistance. When the pulmonary vascular resistance is near, or exceeds, the systemic vascular resistance, the shunt reverses. The resultant right to left shunting results in hypoxia and cyanosis. The most common defect causing Eisenmenger syndrome is a VSD. Other causes include, among others, PDAs, atrioventricular septal defects, and ASDs. Traditionally these patients have been treated with supportive measures. However, studies have shown the beneficial use of oral pulmonary vasodilators, bosentan (an endothelin blocker), and sildenafil (a nitric oxide promoter). These agents decrease pulmonary artery pressure, improve functional capacity and have a mortality benefit. However, these medications are costly and it remains unclear which patients benefit most. Regardless, all Eisenmenger patients should be assessed by an appropriate specialist regarding the use of pulmonary vasodilator.

15. When should an Eisenmenger patient be phlebotomized?

    In Eisenmenger syndrome, hypoxia resulting from the right to left shunt stimulates marrow production of red blood cells and leads to an elevated hematocrit. Historically, Eisenmenger patients were phlebotomized routinely because an elevated hematocrit was thought to predispose to a thrombotic event, as with patients with the hematologic condition polycythemia vera. However, in recent years, data suggest that prophylactic phlebotomy in Eisenmenger patients may be more harmful than beneficial (i.e., it causes iron deficiency, decreases exercise tolerance, potentially increases the risk of stroke). As such, the use of phlebotomy has become more restrictive and should only be considered in two situations:

In modern practice, only a minority of Eisenmenger patients should undergo phlebotomy.

16. Which types of congenital heart disease lesions have particularly poor outcomes in pregnancy?

    Very high risk congenital heart disease lesions include the following:

These patients should be counseled accordingly about the significant maternal risks and poor fetal outcomes that are associated with pregnancy.

17. What are the two types of transpositions?

    Transposition complexes can be divided into two groups. In complete transposition of the great arteries (dextro- or D-TGA), the anomaly can be simplistically conceptualized as an inversion of the great vessels (Fig. 45-3, A). The aorta comes out of the right ventricle, and the pulmonary artery comes out of the left ventricle. Desaturated blood is pumped into the systemic circulation, whereas oxygenated blood is pumped into the pulmonary circulation. Without intervention, this condition is associated with very poor outcomes in early infancy.

    Congenitally corrected transposition of the great arteries (levo- or L-TGA) can be conceptualized as an inversion of the ventricles (see Fig. 45-3, B). Desaturated blood and oxygenated blood are thus pumped in the appropriate arterial circulations. In many cases, associated anomalies, such as a VSD, pulmonary stenosis, an abnormal tricuspid valve, and heart block, are present. These patients can survive or present de novo in adulthood without surgical intervention.

18. What is meant by a systemic right ventricle?

    A systemic right ventricle refers to a heart anomaly where the morphologic right ventricle pumps blood into the aorta. Ventricular morphology is determined by anatomic features typical to each ventricle. For example, the morphologic right ventricle has a tricuspid atrioventricular valve (with attachments to the septum and apical displacement compared with the mitral valve) and coarse apical trabeculations. L-TGA (see Question 17) is a congenital heart defect in which there is a systemic right ventricle. In the first few decades of life, the right ventricle is able to handle pumping into the high-pressure systemic circulation; however, in adulthood, the right ventricular function begins to deteriorate in the majority of patients. This is usually associated with tricuspid regurgitation and manifests clinically as heart failure.

19. What is the difference between an atrial and an arterial switch?

    An atrial switch is a surgical procedure that was previously done for patients born with D-TGA (Fig. 45-4, A). The Mustard and Senning procedures are both examples of an atrial switch and involve rerouting systemic and pulmonary venous flow to the respective pulmonary and systemic ventricles. These procedures were replaced by the arterial switch, which consists of “switching” the great arteries and reimplanting the coronary arteries to the new aorta (see Fig. 45-4, B). The arterial switch is performed in the first few weeks after birth and has been the standard of care for patients born with D-TGA for more than two decades.

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