CHRONIC MITRAL INSUFFICIENCY

这项实验室研究验证了左心功能的假设 二尖瓣置换术后保留二尖瓣 二尖瓣装置在慢性二尖瓣病变中的拴系作用 反胃。二尖瓣反流的慢性模型已经建立。 对绵羊的广泛研究。由于正在逐步扩大的 二尖瓣前叶缺如，左侧明显增多 心脏重量、室壁厚度、左心室重量与体重的比率， 7-8个月的舒张末容量、每搏量和射血分数 与对照相比的期间。二尖瓣环乳头肌 慢性二尖瓣置换术后的间断 心室负荷过重，导致舒张期末显著增加 体积，从而创造了一个增加的“有效”预加载。这导致了一个 继发于赤道短轴增加的每搏量增加 正在缩水。尽管前向流量有所增加，但左翼的储备 慢性二尖瓣返流的心室进行压力-容量功 严重受损，最大值大幅下降 匹配心率和前负荷时的收缩压和最大dp/dt 所有患者均切断肌腱索。这些数据表明，维护 二尖瓣术后二尖瓣环乳头肌连续性的研究 置换术在慢性心力衰竭患者左心功能中的保护作用 继发于二尖瓣返流的容量超载。

This laboratory study tested the hypothesis that left ventricular function following mitral valve replacement may be better preserved by retaining the tethering effect of the mitral valve apparatus in chronic mitral regurgitation. A chronic model of mitral regurgitation has been developed an extensively studies in sheep. Due to the progressive enlargement of an anterior mitral leaflet defect, there were significant increases in left ventricular mass, wall thickness, LV mass to body weight ratio, end-diastolic volume, stroke volume and ejection fraction over a 7-8 month period compared to controls. Mitral annular - papillary muscle discontinuity following mitral valve replacement in chronic, volume overloaded ventricles, led to a significant increase in the end-diastolic volume thus creating an increased "effective" preload. This resulted in an increased stroke volume secondary to increased equatorial, minor axis shortening. Despite this increase in forward flow, the reserve of the left ventricle with chronic mitral regurgitation to perform pressure-volume work was severely impaired with dramatic, significant decreases in maximum systolic blood pressure and max dp/dt at matched heart rates and preload after all chordae tendinae were severed. These data show that maintenance of mitral annular-papillary muscle continuity following mitral valve replacement preserves left ventricular function in setting of chronic volume overload secondary to mitral regurgitation.