Movements of the Mitral Valve

Cinefluorographic analysis of mitral valve motion in intact dogs provided evidence that the motility of the valve cusps is restrained by tension exerted through the chordae tendineae throughout the cardiac cycle, except for the rapid filling phase. At the onset of ventricular systole, early contraction of the papillary muscles may play an important role in approximating the mitral valve cusps. During ventricular ejection, the mitral cusps and valve ring move toward the apex of the heart. During diastole, separation of the valve cusps is remarkably slight. The valves were observed to fling wide during rapid ventricular filling when the heart was much smaller than normal, immediately after surgery.