A. The opening snap of mitral stenosis
B. The click of mitral valve prolapse
C. The systolic ejection click of a bicuspid aortic valve
D. A pericardial knock
Standing from a squatting position decreases venous return as well as left ventricular filling. The click from mitral valve prolapse occurs sooner in systole in this setting since left ventricular volumes are lower and the pressure in the left ventricle an increase quicker from contraction causing the mitral valve to prolapse.