Phonocardiogram of mitral stenosis as recorded from the apex

Electrocardiogram and phonocardiogram of mitral stenosis as heard at the apex. A presystolic murmur or rumble of mitral stenosis precedes S1, a result of increased blood flow from atrial contraction. Following S2 (closure of the aortic and pulmonic valves) is the opening of the stenotic mitral valve (snap) and the low pitch middiastolic murmur or rumble of mitral stenosis.