Fig. 2.

Potential mechanism of late systolic mitral valve prolapse (MVP) with augmented mitral valve (MV) superiorly pushing force and MV annulus dilatation. Left ventricular (LV)-to-left atrial (LA) systolic pressure gradient physiologically pushes MV leaflets superiorly (panel at left). This force can be calculated as LV-to-LA pressure gradient × MV annular area and expresses the papillary muscle (PM) traction force. In patients with late systolic MVP (panel in middle), the MV superiorly pushing force as well as PM traction force can be augmented with marked annular dilatation, which may potentially lead to abnormal superior shifts of MV leaflets that cause PM traction. After surgical MV plasty with annulus size reduction (panel at right), the MV superiorly pushing force as well as PM traction force can be considerably reduced, which may attenuate or eliminate the preoperatively observed abnormal superior shifts of both MV leaflets and PMs.