Figure 1. Schematic diagram of currently accepted echocardiographic criteria for diagnosis of mitral valve prolapse. Top. Two-dimensionally targeted M-mode recordings of continuous mitral leaflet interfaces show (top left) late systolic prolapse, with prolapse beginning in mid-systole (P) and characterized by at least a 2-mm posterior displacement of leaflets behind the valve's C-D line and confirmed by demonstration of leaflet billowing in the two-dimensional parasternal long-axis view. Bottom. Two-dimensional, parasternal long-axis view showing systolic billowing of mitral leaflets (arrows) into the left atrium (LA), a motion the posterior component of which may be detected by the vertically oriented M-mode beam (M). Hatched areas indicate muscular walls of left ventricular myocardium, and dotted lines show normal position of mitral leaflets and annulus. Ao = aorta; LV = left ventricle. Reprinted with permission from R. B. Devereux et al.: Mitral valve prolapse: Causes, clinical manifestations and management. Ann Intern Med 1989; 111:305-17.