[Midsystolic closure of the aortic valve in hypertrophic nonobstructive cardiomyopathy].

Midsystolic cessation of left ventricular contraction was documented in a patient with hypertrophic nonobstructive cardiomyopathy (HCM) associated with Cushing's syndrome (adrenal adenoma) without history of hypertension. The carotid pulse tracing showed a rapid upstroke with a prominent percussion wave which was rapidly decayed at midsystole followed by a tiny tidal wave. The decay of this percussion wave coincided in timing with midsystolic closure of the aortic valve in the echocardiogram. The left ventricle (LV) was symmetrically hypertrophied (wall thickness = 1.8 cm). The motion of the interventricular septum and LV posterior wall appeared trapezoid, and the contraction of these walls was normal in early-systole followed by the sudden cessation at midsystole till end-systole. Systolic anterior motion of the mitral valve was not observed. Cardiac catheterization revealed no pressure gradient in the LV even after the various provocative maneuvers. The left ventriculogram simultaneously recorded with LV pressure showed that LV ejection was completed at midsystole, when LV pressure fell from 98 to 83 mmHg. Mitral regurgitation was not observed. Midsystolic cessation of left ventricular contraction in this case is thought to be the cause of sudden interruption of forward aortic flow, resulting in a bifid carotid pulse and midsystolic closure of the aortic valve in the echocardiogram.