心肌声学造影定量评价缺血预适应对犬心肌缺血再灌注损伤的保护作用

目的应用新技术心肌声学造影（MCE）评价缺血预适应（IP）对犬心肌缺血再灌注（IR）损伤的保护作用。方法将15条杂种犬随机分为两组：IR组，持续缺血3h后再灌注2h；IP＋IR组，在持续缺血前进行4次短暂性缺血5min，中间间隔5min再灌注。采用前降支动脉套扎建立IP开胸犬模型，分别于基础状态、缺血3h和再灌注2h行MCE；测量两组左室射血分数（EF），计算EF恢复值；处死犬后，采用2％红四氮唑将心肌染色，测量坏死区（NA）和危险区（RA）面积，计算NA／RA，与MCE缺损面积比较。结果两组缺血3h和再灌注2hEF值较基础状态明显下降，再灌注2h后均有改善；再灌注2hIP＋IR组EF恢复程度好于IP组。各组缺血再灌注后心内膜下心肌出现不同程度的坏死区，MCE和TTC染色2种方法测量值高度正相关。MCE和TTC染色显示IP＋IR组NA／RA值较IR组降低。结论MCE为定量评价IP对IR损伤的保护作用提供了一种有效方法。

Myocardial Contrast Echocardiographic Assessment of Protective Effect of Ischemic Preconditioning on Myocardial Ischemia Reperfusion Damage

Objective To evaluate the protective effects of ischemic preconditioning (IP) on canine heart model with myocardial contrast echocardiography (MCE) technique to assess myocardial ischemic reperfusion (IR) dynamically.Methods Fifteen mongrel dogs were divided into two groups:IR group and IP+IR group.LAD was occluded for 3 hours,then the heart was reperfused for 2 hours.MCE was performed at different time intervials in both groups,and left ventricular EF was also measured.After the experiment,the heart slices corresponding to the echocardiographic imaging planes were immersed into triphenyltetrazolium chloride (TTC) and necrosis area (NA),risk area (RA) and NA/RA were calculated.Results EF was decreased apparently both after occlusion and reperfusion within 2 h,but after reperfusion,EF became better and recovered more obviously in the IP+IR group than that in the IR group(P<0.0001).The infarction area measured by MCE was well correlated with the result from pathological stain analysis.NA/RA determined by MCE and pathologic staining were both larger in the IR group than that in the IP+IR group (P<0.01).Conclusions MCE as an effective method can be used to objectively evaluate the protective effects of IP on myocardial ischemia and reperfusion damage in canine hearts.