Early systolic clicks due to mitral valve prolapse.

Four patients had evidence that mitral valve prolapse was the etiology of isolated early systolic clicks that were "ejection" in timing, that is, within 80 msec of the first heart sound (S1). Phonocardiography demonstrated movement of the click closer to S, (three patients) with no change (three patients) or an increase in click amplitude (one patient) on inspiration. Earlier movement of systolic clicks on inspiration is a known feature of midsystolic clicks related to mitral valve prolapse but not of true aortic ejection sounds. In three patients the early systolic click showed a variable relation to the carotid upstroke, suggesting that the two events were not related. The click of the fourth patient occurred after the carotid upstroke. In one patient the click could be brought out by standing. Apical holosystolic murmurs could be elicited in all patients. Leftand right-heart catheterizations and left ventricular angio-