[Experimental study of the effects of mild hypothermia on the acute myocardial infarction size in the rabbits with coronary artery reperfusion].
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 centigrade after occluded for 30 minutes, while the control group's body temperature were kept above 38 centigrade. 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 (2646.9+/-1227.3) U/L, it was significantly lower than that in the control group (4787.8+/-1934.2) 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).


CONCLUSIONS
Mild hypothermia may reduce infarct size in the rabbits with transient acute myocardial infarction, and increase survived myocardium in the risk zone.
Emergency Department of the Chinese PLA General Hospital, Beijing 100853, China.
Yuan-yu
YY
Qian
Qing-yi
QY
Meng
Zhi-zhong
ZZ
Wang
Yong
Y
Ma
Yun-zhong
YZ
Wang
Zhen-nan
ZN
Dong
D000818:Animals; D001794:Blood Pressure; D001831:Body Temperature; D003402:Creatine Kinase / Q000032:analysis; D052279:Creatine Kinase, MB Form; D004195:Disease Models, Animal; D004562:Electrocardiography; D007036:Hypothermia, Induced; D007527:Isoenzymes / Q000032:analysis; D009203:Myocardial Infarction / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology; D015425:Myocardial Reperfusion; D009206:Myocardium / Q000378:metabolism / Q000473:pathology; D011817:Rabbits; D011897:Random Allocation
D007527:Isoenzymes; D003402:Creatine Kinase; D052279:Creatine Kinase, MB Form