亚低温疗法减少家兔再灌注急性心肌梗死范围的实验研究

Experimental study of the effects of mild hypothermia on the acute myocardial infarction size in the rabbits with coronary artery reperfusion

目的 探讨亚低温对家兔缺血再灌注急性心肌梗死 (AMI)范围的影响。方法 14只家兔随机分为亚低温组和常温组 ,结扎心脏冠状动脉前降支造成 AMI,4 5 min后松开结扎线 ,进行再灌注 2 h;动物的中心体温通过热敏电阻探头测定。亚低温组通过物理降温使结扎后 30 m in体温降到 35℃以下 ,此后保持在32～ 35℃ ;常温组体温维持在 38℃以上。再灌注结束后取出心脏染色切片 ,计算梗死心肌、濒危心肌和左室心肌的质量。结果 亚低温组心电图胸前导联抬高幅度之和低于常温组〔(2 5 .8± 8.5 ) m V比 (37.7±6 .5 ) m V,P=0 .0 2 1〕。亚低温组梗死 3h的血清肌酸激酶同工酶 (CK MB)活性改变明显低于常温组〔(2 6 4 6 .9± 12 2 7.3) U / L比 (4787.8± 1934.2 ) U / L ,P=0 .0 4 5〕。组织学检查显示亚低温组梗死心肌质量(0 .2 3± 0 .0 5 ) g明显低于常温组 (0 .4 2± 0 .16 ) g(P=0 .0 2 0 )。亚低温组梗死心肌占濒危心肌的比例 (0 .2 14±0 .0 4 4比 0 .35 7± 0 .0 6 6 ,P=0 .0 0 1)和占左室心肌质量的比例 (0 .0 4 1± 0 .0 10比 0 .0 71± 0 .0 2 7,P=0 .0 2 9)均小于常温组 ;亚低温组存活心肌占濒危心肌的比例高于常温组 (0 .786± 0 .0 4 4比 0 .6 4 3± 0 .0 6 6 ,P<0 .0 0 1)。

Objective To study the effect of mild hypothermia on the acute myocardial infarction size in the rabbits with coronary artery reperfusion. Methods Fourteen rabbits were randomly divided into two groups: mild hypothermia group and control group. Each group underwent 45 minutes of left anterior descending coronary artery occlusion and 2 hours of reperfusion. 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 above 38 ℃. The myocardial area at risk and the infarct area were determined with Evan's blue dye and triphenyl tetrazolium chloride(TTC). Results The total elevated amplitude of ST segment in chest leads V1, V3 and V5 in the mild hypothermia group was (25.8±8.5)mV, it was lower than that in the control group (37.7±6.5)mV( P=0.021). The changes of serum MB isoenzyme of creatine kinase (CK-MB) activities in mild hypothermia group was (2 646.9±1 227.3)U/L, it was significantly lower than that in the control group (4 787.8±1 934.2)U/L(P=0.045). The weight of infarct myocardium of the mild hypothermia group was (0.23±0.05)g, it was lower than that in the control group(0.42±0.16)g (P=0.020). Myocardial infarct size as a percentage of the risk zone(0.214±0.044 vs. 0.357±0.066, P=0.001) and of the left ventricle weight(0.041±0.010 vs. 0.071±0.027, P=0.029) were smaller than those in the control group. The ratio of the survived myocardial area over the risk zone in the mild hypothermia group was significantly higher than that in the control group (0.786±0.044 vs. 0.643±0.066, P<0.001). Conclusion Mild hypothermia may reduce infarct size in the rabbits with transient acute myocardial infarction, and increase survived myocardium in the risk zone.