Pulmonary Stenosis

Essentials of Diagnosis

• No symptoms in patients with mild or moderately severe lesions.
  
• Severe cases may present with right-sided heart failure and cause sudden death.
  
• High-pitched systolic ejection murmur maximal in the second left interspace. P₂ delayed and soft or absent. Ejection click often present. Increased right ventricular impulse.
  
• Palpable thrill at second left intercostal space.
  
• Right ventricular hypertrophy on ECG; pulmonary artery dilation on x-ray. Echo-Doppler diagnostic.

General Considerations

Stenosis of the pulmonary valve or infundibulum increases the resistance to outflow, raises the right ventricular pressure, and limits pulmonary blood flow. In the absence of associated shunts, arterial saturation is normal, but severe stenosis causes peripheral cyanosis by reducing cardiac output.

Clubbing and polycythemia do not develop unless a patent foramen ovale or atrial septal defect is present, permitting right-to-left shunting.

Clinical Findings

A. Symptoms and Signs
Mild cases (right ventricular-pulmonary artery gradient < 30 mm Hg) are asymptomatic. Moderate to severe stenosis (gradients 50 to > 80 mm Hg) may cause dyspnea on exertion, syncope, chest pain, and eventually right ventricular failure.

There is a palpable parasternal lift. A loud, harsh systolic murmur and a prominent thrill are present in the left second and third interspaces parasternally; the murmur is in the third and fourth interspaces in infundibular stenosis. The second sound is obscured by the murmur in severe cases; the pulmonary component is diminished, delayed, or absent. Both components are audible in mild cases. A right-sided S4 and a prominent a wave in the venous pulse are present in severe cases.

B. Electrocardiography and Chest X-Ray
Right axis deviation or right ventricular hypertrophy is noted; peaked P waves provide evidence of right atrial overload. Heart size may be normal on radiographs, or there may be a prominent right ventricle and atrium or gross cardiac enlargement, depending upon the severity. There is often poststenotic dilation of the main and left pulmonary arteries. Pulmonary vascularity is normal or diminished.

C. Diagnostic Studies
Echocardiography usually demonstrates the anatomic abnormality and assesses right ventricular size and function. Doppler ultrasound can estimate the gradient accurately; its findings are usually confirmed by cardiac catheterization.

Prognosis & Treatment