The systolic ejection murmur in hyperophic obstrucive cardiomyopatthy is diminished when a patient-

The physical examination typically reveals a harsh murmur heard best at the left lower sternal border, arising from both the outflow tract turbulence during ventricular ejection and the commonly associated mitral regurgitation. The gradient and the murmur may be enhanced by maneuvers that decrease ventricular volume, such as the Valsalva maneuver, or standing after squatting. They may be decreased by increasing ventricular volume or vascular resistance, such as with squatting or handgrip. ( Harrison&;s principle of internal medicine,18th edition,pg no. 1968)