Ultrasono-cardiographic diagnosis of the prolapsed mitral valve

The characteristic ultrasono-cardiographic (UCG) findings of prolapsed mitral valve were studied in 9 cases by means of ultrasonocardiotomography (UCT). The changes in degree and shape of the prolapsed valve were examined and the leaflet involved was identified. Of the 9 cases, 5 had prolapse of anterior, 3 had that of posterior leaflet and 1 had both. In all cases with midsystolic click and late systolic murmur or pansystolic murmur with late systolic accentuation, the prolapse of anterior leaflet was observed on UCT, and though UCG disclosed midsystolic buckling it was difficult to determine the exact timing of the prolapse by UCG alone. In the cases with rheumatic mitral regurgitation, the prolapse of posterior leaflet and the ballooning of anterior leaflet could easily be found on UCT, but the detection of the above-mentioned 2 findings was difficult by UCG alone. Three of the 9 cases were found to have prolapse of posterior leaflet by left ventriculography, whereas these 3 had prolapse of anterior leaflet on UCT. Hence, the diagnosis of prolapsed mitral valve based on the cineangiography may require re-evaluation.