Pulmonary stenosis - valve disease

Pulmonary stenosis

Definition

Narrowing of the pulmonary valve, resulting in pressure overload of the right ventricle.

Aetiology

This is almost invariably a congenital lesion either as an isolated lesion or as part of the tetralogy of Fallot. Rarely it may be an acquired lesion secondary to rheumatic fever or the carcinoid syndrome.

Pathophysiology

The obstruction to right ventricular emptying results in right ventricular hypertrophy and hence decreased ventricular compliance, which leads to right atrial hypertrophy. If severe, the condition leads to right

ventricular failure, often with accompanying regurgitation of the tricuspid valve and signs of right-sided heart failure.

Clinical features

Severe pulmonary obstruction leads to right-sided heart failure in the first few weeks of life. Patients with mild pulmonary stenosis are asymptomatic (diagnosed incidentally from the presence of a murmur or the presence of right ventricular hypertrophy on the ECG). Patients may have non-specific symptoms such as fatigue or dyspnoea. Syncope is a sign of critical stenosis, which requires urgent treatment.

On examination a large ‘a’ wave may be seen in the JVP. Auscultation reveals a click and harsh mid-systolic ejection murmur heard best on inspiration in the left second intercostal space often associated with a thrill. A left parasternal heave may also be felt due to right ventricular hypertrophy.

Investigations

·        Chest X-ray may show a prominent pulmonary artery due to post-stenotic dilation.

·        ECG may reveal right ventricular strain or hypertrophy indicating the degree of stenosis.

·        Echocardiography is used to examine and quantify the flow across the stenosed valve. It is also essential to identify any associated cardiac lesions such as tetralogy of Fallot. Assessment of right ventricular function is essential.

·        Cardiac catheterisation may be used to assess the level and degree of the stenosis.

Management

Mild stenosis does not require treatment. In more severe cases intervention is required before decompensation of the right ventricle occurs. Balloon dilatation has more or less replaced the need for surgery except in the context of more complex congenital heart disease.