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本实验在21只麻醉开胸狗身上观察了利用等容血液稀释降低血液粘度对心肌缺血早期冠脉侧支血流量与心肌损伤的影响。实验结果表明,阻断冠脉血流30分后,对照组低切变率下全血比粘度(η_(b1))逐渐增加,而侧支血流量(CF)则逐渐减少。缺血75分时,η_(b1)增加18.1±3.9%,CF减沙24.1±4%,心外膜电图ST段持续明显抬高,心肌超微结构显示线粒体破坏、肌原纤维自溶以及微血管内血细胞阻塞等损伤性变化。血液稀释组缺血30分时的各项指标与对照组均无明显差异,此时行轻度等容血液稀释后,上述各项指标均发生明显改善,缺血75分时,η_(b1)较对照值降低25.5±3.9%,CF增加54.7±10.8%,原已抬高的ST段发生显著降低,心肌超微结构的损伤性变化也明显减轻。上述结果提示,急性心肌缺血早期血液流变学的异常变化是加重心肌缺血性损伤的重要因索,而降低血液粘度以增加侧支血流量具有保护缺血心肌的作用。
In this experiment, 21 anesthetized thoracotomic dogs were observed on the use of isovolemic hemodilution to reduce blood viscosity of myocardial ischemia in early coronary collateral flow and myocardial injury. The experimental results showed that after the coronary blood flow was blocked for 30 minutes, the whole blood viscosity (η b1) gradually increased and the collateral blood flow (CF) decreased gradually at the low shear rate of the control group. At 75 minutes after ischemia, the η_ (b1) increased 18.1 ± 3.9% and the CF decreased 24.1 ± 4%. The ST segment of epicardial electrocardiogram was significantly elevated, the myocardial ultrastructure showed mitochondrial destruction, myofibrillar autolyzation and Microvascular blood cell obstruction and other injuries. The index of ischemia at 30min in the hemodilution group was not significantly different from that in the control group. After mild isovolemic hemodilution, the above indexes were significantly improved. At 75min after ischemia, η_ (b1) 25.5 ± 3.9% and 54.7 ± 10.8% lower than the control value respectively. The elevated ST segment was significantly reduced, and the damage of myocardial ultrastructure was also significantly reduced. The above results suggest that abnormal changes of hemorheology in early stage of acute myocardial ischemia are important factors to aggravate myocardial ischemic injury, while reducing blood viscosity to increase collateral blood flow has the function of protecting ischemic myocardium.