Mitral valve prolase - valve disease

Mitral valve prolase

Definition

Prolapsing mitral valve is a condition in which the valve cusps prolapse into the left atrium during systole. It is also known as floppy mitral valve. A particular form of prolapse may result from myxomatous degeneration of the leaflets named Barlow’s syndrome.

Incidence

Echocardiography reveals prolapsing mitral valve in 5% of the normal population; however, not all are clinically significant, especially in the absence of any mitral incompetence.

Age

Young adulthood.

Sex

F > M

Aetiology

Often there is no obvious underlying cause. Associated with Marfan’s syndrome, thyrotoxicosis, rheumatic or ischaemic heart disease. There is also a familial element. It is thought to be due to progressive stretching of the valve leaflets.

Pathophysiology

The normal anatomy of the mitral valve prevents prolapse thus one or more anomalies must be present: excessively large mitral valve leaflets, an enlarged mitral annulus, abnormally long chordae or disordered papillary muscle contraction. During systole one of the valve leaflets (usually the posterior) balloons up into the atrium. In some cases this causes retraction at the normal point of contact of the valve cusps and hence mitral regurgitation. The condition does not often cause significant regurgitation.

Clinical features

Most patients are asymptomatic but some complain of left submammary stabbing chest pain. On auscultation there may be a midsystolic click, with a late systolic (or occasionally pansystolic) murmur if regurgitation occurs.

Complications

Rupture of one of the chordae may occur leading to severe acute valve regurgitation. Arrhythmias including supraventricular tachycardia and complex ventricular ectopy may occur. There is an increased risk of thromboembolism and infective endocarditis.

Investigations

ECG may be normal or show minor ST abnormalities. Echocardiography shows the mid-systolic bulging of

the valve leaflets.

Management

β-blockers are used in patients with chest pain or palpitations. Patients with mitral valve regurgitation require prophylaxis against infective endocarditis. Patients with coexisting atrial fibrillation should be anticoagulated. Rarely severe cases may require valve repair or replacement.