Study for Mitral B-Bump and Its Relation to Left Ventricular Dysfunction by M-Mode Echocardiography

Yoo, Hyeon Yeong; Shin, Gil Ja

Abstract

Normally the AC segment of mitral valve echogram consists of a rapid slope, from A peak to C point(complete closure). The initial portion is usually less steep than its final portion ; the latter represents abrupt mitral valve closure secondary to the rapid rise in left ventricular(LV) pressure at the onset of LV systole. The point on the mitral echogram at which closure aburptly accelerates in the B point. In order to see wither or not the echocardiographically recorded mitral valve could reflect alterations in left ventricular pressure, mitral valve echograms and left ventricular pressure were obtained on 30 patients undergoing diagnostic cardiac catheterization. The results were as follow : 1) Of 23 patients with LV ejection fraction>55%(71.2%+/-7.9%), 2 had B-bump ; of 7 patients with LV ejection fraction<55%(47.0%+/-4.9%), 5 had B-bump. The difference in frequency of B-bump between the normal LV ejection fraction and the low LV ejection fraction groups was statistically significant(p<0.001). 2) Of 6 patients with LVEDP>5mmHg (17.7mmHg+/-3.6mmHg), 5 had B-bump ; of 24 patients with LVEDP<15mmHg (8.5mmHg+/-2.6mmHg), 2 had B-bump. The difference in frequency of B-bump between the normal LVEDP and the elevated LVEDP groups was statistically significant(p<0.001). 3) Of 22 patients with LV ejection fraction>55%(71.2%+/-7.9%), as well as LVDEP<15mmHg(8.5mmHg+/-2.6mmHg), 1 had B-bump ; Of 5 patients with LV ejection fraction<55%(47.0+/-4.9%), as well as LVEDP>15mmHg(17.8mmHg+/-3.6mmHg), 4 had B-bump. The difference in frequency of B-bump between in normal LV ejection fraction, as well as normal LVEDP and the low LV ejection fraction, as well as elevated LVEDP groups was statistically significant(p<0.001). Thus, the mitral B-bump correlated primarily with LV dysfunction. When properly recorded, the presence of a B-bump is a useful sign of significantl LV dysfunction.