A mid-diastolic murmur with an opening snap, almost always rheumatic
Expansion
Signs
- Malar flush, a plum coloured cheek discolouration
- Irregularly irregular pulse, from atrial fibrillation
- Tapping, non-displaced apex, the palpable first heart sound
- Loud S1, an opening snap, and a low pitched mid-diastolic rumbling murmur with presystolic accentuation if in sinus rhythm
- Best heard at the apex, in the left lateral position, on expiration, with the bell
Severity markers: a shorter S2 to opening snap interval, a longer murmur, and signs of pulmonary hypertension (loud P2, right ventricular heave, tricuspid regurgitation).
“The closer the snap, the tighter the valve.”
Cause is overwhelmingly rheumatic fever, which is why it is now rare in the UK and common where rheumatic disease persists, and why it affects women more often.
Complications follow from left atrial enlargement and pulmonary congestion: atrial fibrillation, systemic embolism and stroke, pulmonary hypertension, right heart failure, haemoptysis, and hoarseness from left recurrent laryngeal nerve compression (Ortner’s syndrome).
Pregnancy decompensates it, because the increased heart rate shortens diastole and the increased volume raises left atrial pressure.