diastolic murmur

A diastolic murmur is the sound of turbulent blood flow heard during diastole — the phase when the ventricles relax and fill — that is, after the second heart sound and before the next first heart sound. It is the counterpart of the systolic murmur, occurring in the heart's resting half of the cycle.

Again, timing reveals the mechanism. During diastole the mitral and tricuspid valves should be open (so a narrowed one creates a filling murmur) while the aortic and pulmonary valves should be shut (so a leaking one creates an early-diastolic murmur). Hence mitral or tricuspid stenosis and aortic or pulmonary regurgitation are the classic causes.

A practical point sets diastolic murmurs apart from systolic ones: whereas many systolic murmurs are innocent, a diastolic murmur is almost always pathological and warrants evaluation. They can also be soft and easily missed, so they are sought with careful positioning and listening. Echocardiography confirms the responsible valve lesion.

The presence of a diastolic murmur is a finding to be evaluated by a clinician; this entry is descriptive reference only.