中文摘要：

目的：应用分析和比较基于压力相平面（PPP）推导的心室等容舒张期时间常数（τ）和室腔僵硬度常数（K）在离体大鼠心脏缺血／再灌注过程中的变化，探讨其在评价左心室舒张功能异常中的价值。方法：采用SD大鼠心肌不同时程缺血／再灌注模型，分别计算出LVEDP、-（dp／dt）max、τ和K。同时，检测冠脉流出液中的乳酸脱氢酶（LDH），并进行心肌电镜观察。结果：在再灌注过程中，τ在各缺血组均明显高于空白对照组（P〈0．05），K在各缺血组均明显低于空白对照组（P〈0．05）；而且，随着缺血时间延长，τ更高，K更低（P〈0．05）。除了缺血15min组，其余各组LDH含量在再灌注10min和20min时均高于空白对照组（P〈0．05）；缺血45min组和缺血60min组LDH含量在再灌注10min和20min时均高于缺血30min组（P〈0．05）。随着缺血时间延长，心肌超微结构发生异常改变。结论：基于PPP推导的τ和K可以作为定量评价离体大鼠心脏缺血／再灌注过程中的左心室舒张功能的指标，还可以反映缺血／再灌注损伤的严重程度。

英文摘要：

AIM ： To analyze and compare the changes of pressure phase plane （PPP） derived r and K on isolated rat heart during isehemia/reperfusion, and to explore the value of PPP derived τ and K for evaluation of left ventrieular diastolic dysfunction. METHODS： LVEDP, -d（p/dt）max, τ and K were measured and calculated during ischemia/reperfusion in Sprague - Dawley rat hearts. Meanwhile, the level of lactate dehydrogenase （LDH） in the coronary effluent was measured, and the ultrastructure changes in myoeardium were observed under electron microscope. RESULTS： Compared with control group, τ increased and K reduced significantly in each ischemic group in a time dependent manner （P 〈 0. 05）. With prolonged isehemia, τ was even higher and K was even lower （P 〈0. 05）. Compared with control group, except isehemia 15 min, LDH in other groups increased significantly at 10 rain and 20 min after reperfusion （P 〈0. 05）. Compared with isehemia 30 min, LDH of isehemia 45 min and isehemia 60 min were even higher at 10 min and 20 rain after reperfusion （P 〈 0. 05）. With prolonged ischemia, the abnormal changes of the myocardial ultrastructure were observed. CONCLUSION： PPP derived τ and K may be promising indexes for quantitative assessment of left ventrlcular diastolic function on isolated rat heart during ischemia/reperfusion, and indication of the severity of ischemia/reperfusion injury.