PULMONiC STENOSiS

Etiology and Pathogenesis

RV outflow obstruction may be subvalvular, valvular, or supravalvular (Fig. 38-3). Both the subvalvular and the supravalvular forms of RV outflow obstruction are usually associated with other congenital heart disease, as discussed in Section VIII. True valvular pulmonic stenosis, however, usually occurs as an isolated congenital defect. In addition, it may occur as the sole cardiac abnormality in patients with Noonan’s syndrome. Rarely, pulmonic stenosis is due to rheumatic disease, endocarditis, or carcinoid syndrome.

Clinical Presentation

Patients with pulmonic stenosis are often asymptomatic. Patients may reach the fourth through sixth decades of life with significant pressure gradients across the pulmonic valve but with no symptoms and no evidence of right-sided heart failure. If right-sided heart failure does develop, abdominal swelling, peripheral edema, abdominal discomfort, and fatigue may be present. Patients seldom present with chest pain or exertional syncope.

The physical examination typically reveals a mid systolic crescendo-decrescendo murmur at the left sternal edge. Often, an associated ejection click, which usually decreases with inspiration, is present. P2 is soft and delayed, producing a widely split S2, but one that does narrow with appropriate physiologic changes (unlike the fixed, widely split S2 present in patients with an atrial septal defect). Occasionally, a right-sided S4 is appreciated at the left sternal border. An RV lift may also be present. If RV failure is present, there may be peripheral edema, hepatomegaly, abdominal swelling, and jugular venous distention with a prominent a wave.

Pulmonary valvular stenosis with intact septum: Hypertrophy of right ventricle

Stenotic pulmonary valve viewed from above: Poststenotic dilatation of pulmonary trunk

Bicuspid pulmonary valve

Figure 38-3 Pulmonary valvular stenosis and atresia.


Complete atresia of •  '

Pulmonary valve


Diagnostic Approach

Electrocardiography may be normal with mild-to-moderate stenosis, but in more severe cases will often reveal right-axis deviation, RA enlargement, and RV hypertrophy. A complete or incomplete right bundle branch block is sometimes present, although patients with Noonan’s syndrome characteristically have a left bundle branch block. Chest radiography reveals poststenotic dilatation of the pulmonary artery but diminished peripheral pulmonary vascular markings. RV hypertrophy and enlargement are highly variable.

Echocardiography with Doppler evaluation is useful for establishing the diagnosis and assessing therapy. Morphologic assessment is best performed with the parasternal short-axis and subcostal views and will generally reveal thickened but pliable leaflets with restricted motion and doming. Occasionally, patients will have more severe thickening with severely dysplas-tic valves. This is important to recognize, because such patients are not well-suited to percutaneous valvuloplasty. Transesophageal echocardiography is not usually necessary but can be performed if a transthoracic study fails to provide an adequate assessment. The right ventricle may be normal, particularly in childhood, but stenosis of long duration, greater severity, or both is usually associated with RV hypertrophy and enlargement. Paradoxical motion of the interventricular septum is often present. Continuous-wave Doppler evaluation is highly reliable in establishing the gradient across the pulmonic valve. Cardiac catheterization is usually not necessary but may be performed if Doppler studies are suboptimal or immediately before (and after) planned balloon valvuloplasty.

Management and Therapy

Adult patients with mild pulmonic stenosis generally do well and require no intervention. More severe disease is appropriately treated with balloon valvuloplasty, which is highly effective. The 2006 American College of Cardiology/American Heart Association guidelines recommend percutaneous valvuloplasty in symptomatic young adults with a systolic gradient greater than 30 mm Hg and asymptomatic patients with a systolic gradient greater than 40 mm Hg.

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