Tsakiris A G, Gordon D A, Mathieu Y, Padiyar R, Labrosse C
J Appl Physiol. 1976 Feb;40(2):132-7. doi: 10.1152/jappl.1976.40.2.132.
The motion of both mitral cusps and the presence of valvular regurgitation during ventricular contractions were investigated in seven experiments on dogs in which radiopaque markers had been sutured to the cusps and the valve annulus 1-32 wk before the studies. Cineangiograms of the left ventricle were obtained during ventricular ectopic beats, interposed throughout the cardiac cycle (20-99% of cycle length) and during induced variations in the P-R interval (0-200 ms). Mitral regurgitation was observed only during a) weak, early ectopic beats (peak pressure below 34 mmHg) which were incapable of closing the cusps and b) when ventricular contractions suddenly interrupted normal leaflet motion toward the ventricle, during three well-defined periods of diastole (diastolic valve opening, diastolic rebound, and atrial opening). Valve closure following sudden reversal of cusp opening was slow and the leaflets often did not arrive simultaneously at their closed positions. These findings suggest that sudden interruption of leaflet opening by ventricular contractions is an important mechanism of transient mitral regurgitation in the normal heart.
在七只犬的实验中，研究了二尖瓣叶的运动以及心室收缩期间瓣膜反流的情况。在研究前1 - 32周，已将不透射线的标记物缝合至瓣叶和瓣膜环。在室性早搏期间、插入整个心动周期（占心动周期长度的20 - 99%）以及诱发P - R间期变化（0 - 200毫秒）时，获取左心室的电影血管造影图像。二尖瓣反流仅在以下情况时观察到：a）微弱的早期室性早搏（峰值压力低于34 mmHg），此时无法使瓣叶闭合；b）在舒张期的三个明确时期（舒张期瓣膜开放、舒张期反弹和心房开放），当心室收缩突然中断瓣叶向心室的正常运动时。瓣叶开放突然逆转后的瓣膜关闭缓慢，且瓣叶常常不能同时到达其关闭位置。这些发现提示，心室收缩导致瓣叶开放突然中断是正常心脏中短暂二尖瓣反流的重要机制。
