Chapter 422 Acyanotic Congenital Heart Disease

Regurgitant Lesions

422.1 Pulmonary Valvular Insufficiency and Congenital Absence of the Pulmonary Valve

Pulmonary valvular insufficiency most often accompanies other cardiovascular diseases or may be secondary to severe pulmonary hypertension. Incompetence of the valve is an expected result after surgery for right ventricular outflow tract obstruction, for example, pulmonary valvotomy in patients with valvular pulmonic stenosis or valvotomy with infundibular resection in patients with tetralogy of Fallot. Isolated congenital insufficiency of the pulmonary valve is rare. These patients are usually asymptomatic because the insufficiency is generally mild.

The prominent physical sign is a decrescendo diastolic murmur at the upper and midleft sternal border, which has a lower pitch than the murmur of aortic insufficiency because of the lower pressure involved. Roentgenograms of the chest show prominence of the main pulmonary artery and, if the insufficiency is severe, right ventricular enlargement. The electrocardiogram is normal or shows minimal right ventricular hypertrophy. Pulsed and color Doppler studies demonstrate retrograde flow from the pulmonary artery to the right ventricle during diastole. Cardiac magnetic resonance angiography (MRA) is useful for quantifying both right ventricular volume and the regurgitant fraction. Isolated pulmonary valvular insufficiency is generally well tolerated and does not require surgical treatment. When pulmonary insufficiency is severe, especially if significant tricuspid insufficiency has begun to develop, replacement with a homograft valve may become necessary to preserve right ventricular function.

Congenital absence of the pulmonary valve is usually associated with a ventricular septal defect, often in the context of tetralogy of Fallot (Chapter 424.1). In many of these neonates, the pulmonary arteries become widely dilated and compress the bronchi, with subsequent recurrent episodes of wheezing, pulmonary collapse, and pneumonitis. The presence and degree of cyanosis are variable. Florid pulmonary valvular incompetence may not be well tolerated, and death may occur from a combination of bronchial compression, hypoxemia, and heart failure. Correction involves plication of the massively dilated pulmonary arteries, closure of the ventricular septal defect, and placement of a homograft across the right ventricular outflow tract.

Bibliography

McDonnell BE, Raff GW, Gaynor JW, et al. Outcome after repair of tetralogy of Fallot with absent pulmonary valve. Ann Thorac Surg. 1999;67:1391-1395.

Pinsky WW. Absent pulmonary valve syndrome. In: Garson A, Bricker JT, Fisher DJ, et al, editors. The science and practice of pediatric cardiology. Baltimore: Williams & Wilkins; 1998:1413-1419.

422.2 Congenital Mitral Insufficiency

Daniel Bernstein

Congenital mitral insufficiency is rare as an isolated lesion and is more often associated with other anomalies. It is most commonly encountered in combination with an atrioventricular septal defect, either an ostium primum defect, or a complete AV septal defect (Chapter 420.5). Mitral insufficiency is also seen in patients with dilated cardiomyopathy (Chapter 433.1) as their left ventricular function deteriorates, secondary to dilatation of the valve ring. Mitral insufficiency may also be encountered in conjunction with coarctation of the aorta, ventricular septal defect, corrected transposition of the great vessels, anomalous origin of the left coronary artery from the pulmonary artery, or Marfan syndrome. In the absence of other congenital heart disease, endocarditis or rheumatic fever should be suspected in a patient with isolated severe mitral insufficiency (Table 422-1).

Table 422-1 CAUSES AND MECHANISMS OF MITRAL REGURGITATION