心肌缺血日负荷对冠状动脉侧支血流量的影响

Effects of daily myocardial ischemic burden on coronary collateral blood flow of rabbits

目的:探讨心肌缺血日负荷对新西兰兔冠状动脉侧支血流量(CCBF)的影响。方法:健康成年新西兰兔34只,体重2.4±0.2kg。随机分为缺血组和假手术组,缺血组根据日缺血负荷分为2、4、6次/日亚组。将气囊梗阻器安装在冠状动脉左室支上,以建立间断性心肌缺血模型。气囊充气造成心肌缺血(2min/次,间隔1h),以各日缺血负荷持续4周。取缺血区心肌观察形态学改变;微球技术检测缺血区CCBF;取兔术前和首次缺血刺激前、后24h血清检测肌钙蛋白(cTn-I)。结果:4周间断性缺血刺激后,缺血组与假手术组相比,CCBF明显增加(P<0.05);各缺血亚组间CCBF差异无显著性意义(P>0.05)。各组缺血区心肌未见变性坏死灶,兔首次缺血刺激后24h血清肌钙蛋白无明显升高。结论:4周间断性心肌缺血对心肌无损伤,可促进缺血区CCBF增加;不同日缺血负荷对CCBF无明显影响。

Objective: To explore the effect of daily myocardial ischemic burden on coronary collateral blood flow (CCBF) of New Zealand rabbit.Method:Intermittent myocardial ischemia model was established by installing a balloon occluder on the left ventricle coronary artery(LVA) in 34 adult New Zealand rabbits. All subjects were assigned to two groups: sham-operate group and ischemic group, which was subdivided into 2, 4 and 6 times subgroups according to daily frequency of ischemic stimulation. Seven days after surgery, 2-min coronary occlusions per hour with different daily ischemic burdens using inflating balloon occluder were performed daily and lasted for 4 weeks, meanwhile ST segment elevation of ECG was adopted as criteria of myocardial ischemia. Ischemic myocardium was sampled for histological examination. CCBF was measured with microsphere technique. Blood serum was obtained on baseline, pre and 24h post the first ischemic stimulation for detecting cardiac troponin I(cTn-I). Result: Compared with sham-operate group,CCBF was obviously increased in ischemic group(P<0.05). There was no significant difference in increase of CCBF among 3 ischemic subgroups(P>0.05). There was no myocardial cell degeneration in all subjects, and no significant increase of blood cTn-I 24h after the first ischemic stimulation.Conclusion:Four weeks of intermittent myocardial ischemic may increase CCBF without irreversible myocardial damage. Increase of daily ischemic frequency does not enhance CCBF further.