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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 To assess the intrinsic contractile force of right ventricular myocardium in left ventricular bypass and to exclude the influence of load by applying the relationship between the end-systolic pressure and volume at right ventricular systolic pressure (ESPVR, expressed as Emax). Methods Pulmonary artery was used to produce isovolumetric contraction. Pulmonary artery flow was recorded synchronously. The integral of this flow and the corresponding right ventricular ejection pressure formed the right ventricular pressure volume ring. The upper left corner of the ring was the end of systole. Systolic blood pressure peak to the end of systole or tangent for a straight line, the slope of Em ax. Six normal hearts and five right ventricular anterior ischemic sheep were treated with left ventricular bypass for 15 minutes at 50%, 75% and 90% of cardiac output respectively, and their Emax was calculated. Results With the increase of left ventricular circulation, the Emax of all right ventricle decreased. There was no significant difference in statistical analysis (P> 0.05). Conclusion High left ventricular circulation may reduce the intrinsic contractility of right ventricular myocardium to a certain extent. The assessment of its total function depends on the diastolic compliance and pulmonary artery resistance.