左心转流时右心室收缩期末压、容积关系的变化

On the Change of End-Systolic Pressure Volume Relation of Right Ventricle During Left Heart Bypass

目的 在左心转流时应用右心室收缩期末压、容积关系 (ESPVR,以 Emax表示 )作为评估右心室心肌固有收缩力的指标 ,从而排除负荷的影响。 方法 采用钳夹肺动脉以产生等容收缩 ,同步持续记录肺动脉流量 ,此流量的积分与相应的右心室射血压相互构成右心室压力容积环 ,此环的左上角即为收缩期末点 ,自等容收缩压的峰值起至收缩期末点或与之相切作一直线 ,其斜率为 Em ax。 6条正常心脏及 5条右心室前壁缺血绵羊以心排血量的5 0 %、75 %和 90 %分别作左心转流各 15分钟 ,计算其 Emax。 结果 随左心转流量的递增 ,全部右心室 Emax均有低落 ,统计学分析差异无显著性 (P>0 .0 5 )。 结论 高左心转流量在一定程度上可使右心室心肌固有收缩力低落 ,对其总功能的评估尚须视其舒张顺应性与肺动脉阻力而定。

Objective\ End systolic pressure volume relation of the right ventricle was determined during left heart bypass as an index to estimate its systolic properties with the hope that the influence of load could be thus eliminated.\ Methods\ Main pulmonary artery was clamped first to produce an isovolumic contraction, simultaneously the pulmonary artery flow was recorded. The end diastolic pressure of the last ejecting contraction of right ventricle should be the same as that of isovolumic contraction and so was the end diastolic volume. A pressure volume loop was constructed by integrating the pulmonary flow with the relevant right ventricular pressure. Drew a line from the peak pressure of the isovolumic contraction to or tangent to the left upper corner of the loop, the slope was Emax. Three sets of left heart bypass flow ie:50%, 75% and 90% of the normal cardiac output were conducted in 6 normal sheep and 5 sheep with localized ischemic areas over the anterior surface of the right ventricle respectively, each lasting for 15 minutes, and 3 sets of Emax were thus obtained.\ Results\ Emax was lowered in both normal and ischemic right ventricles following the increment of left heart flow rate. However, the data was nonsignificant statistically( P >0 05).\ Conclusion\ High left heart bypass flow rate did impair the contractility of the right ventricle. For the evaluation of the over all function of right ventricle, diastolic compliance and pulmonary artery impedance should be taken into consideration.