亚低温对急性心肌梗死早期保护作用的实验研究

Protective effect of body mild hypothermia for acute myocardial infarction in rabbits

目的 :探讨亚低温治疗对家兔急性心肌梗死早期的作用。方法 :36只家兔根据心肌梗死模型不同分为两组 :冠脉持续结扎组 (2 2只 )和冠脉短暂结扎组 (14只 ) ,两组各自再均分为常温组和亚低温组。亚低温组通过物理降温使结扎后 30min动物体温降到 35℃以下 ,保持在 32～ 35℃之间 ;常温组体温维持在 38～ 4 0℃之间。记录体表心电图 ,测量心肌酶 ,测算梗死心肌、濒危心肌和左室心肌的面积。结果 :①心电图胸导联抬高幅度之和亚低温组低于常温组。②亚低温组梗死后血清CK MB水平上升幅度明显低于常温组。③亚低温组梗死心肌面积占濒危心肌面积的比例明显小于常温组 ,占左室心肌面积的比例也小于常温组。结论 :亚低温治疗对家兔急性心肌梗死早期可产生保护作用 ,减小心肌梗死的面积。

Objective: To study the effect of body mild hypothermia for acute myocardial infarction in coronary artery occluded rabbits. Methods: thirty-six rabbits were randomly divided into 2 groups according to the duration of left anterior descending coronary artery occlusion: continuous coronary artery occluded group (CCAO group, n=22) and transient coronary artery occluded group (TCAO group, n=14). Each group was divided into two sub-groups: mild hypothermia group and the control. Core temperatures were measured with thermistor. The mild hypothermia group received ice cooling around the body and the core temperature was dropped to 32-35℃ after occluded for 30 minutes, while the control group's body temperature were kept 38-40℃. Myocardial area at risk and infarct size were determined with Evans blue dye and triphenyl tetrazolium chloride(TTC). Results: (1) The total elevated amplitude of ST segment in chest leads V 1, V 3 and V 5 in the mild hypothermia group were lower than that in the control [CCAO group (22.8±18.7)mV vs (34.7±19.3)mV, P=0.090; TCAO group (25.8 ±8.5)mV vs (37.7±6.5)mV, P=0.021]. (2)The changes of serum CK-MB activities after coronary occlusion in mild hypothermia group were significantly lower than the control group[CCAO group (2672.1±909.1)vs(4192.7±1960.9)U/L,P=0.047; TCAO group(2646.9±1227.3)U/L vs (4787.8±1934.2)U/L,P=0.045]. (3) Myocardial infarct size as a percentage of the area at risk(CCAO group 31.3%±7.6% vs 47.9%±6.6%,P<0.001; TCAO group 21.4%±4.4% vs 35.7%±6.6%,P=0.001)and of the left ventricle size (CCAO group 6.5%±1.3% vs. 11.3%±3.7 %, P<0.001; TCAO group4.1%±1.0% vs 7.1%± 2.7%, P=0.029)of CCAO and TCAO groups were smaller than control groups. Conclusion: Mild hypothermia may have the protective effect for acute myocardial infarction and reduce infarct size in rabbits.