心肌声学造影评价快速心房起搏预适应减小心肌梗死范围的实验研究

目的：探讨心肌声学造影技术评价不同频率快速心房起搏预适应减小缺血再灌注后心肌梗死范围的作用。方法：20条健康成年杂种犬随机分为三组：A组6条，为非缺血性快速心房起搏预适应组；B组7条，为缺血性快速心房起搏预适应组；C组7条，为对照组，A、B两组完成3个回合的快速起搏预适应后，与C组一道结扎阻断左前降支冠脉血流60min，随后灌注60min，在持续缺血和再灌注阶段行心肌声学造影检查（MCE），比较各组缺血再灌注后心肌梗死的面积以及心肌坏死我面积与危险区面积之比（NA／RA），并与氯化三苯四氮唑（TTC）心肌组织染色结果呈高度正相关，结论：缺血性和非缺血性快速心房起搏预应对犬心肌缺血再灌注损伤均有保护作用，缺血性快速起搏预适应的保护效力大于非缺血性起搏预适应，心肌声学造影可以准确评价快速心房起搏预应对心肌缺血再灌注损伤的保护作用。

Experimental study of effect of preconditioning with rapid atrial pacing on myocardial infarct size by myocardial contrast echocardiography

Objective To investigate the protective effect of preconditioning induced by rapid atrial pacing in reducing infarct size using myocardial contrast echocardiography (MCE).Methods Twenty anaesthetized dogs were randomly divided into three groups as follows: nonischemic pacing preconditioned group(group A), ischemic pacing preconditioned group(group B) and control group(group C). In control group,the anterior descending coronary artery was occluded for 60 minutes, subsequently, reperfused for 60 minutes. In preconditioned groups of dogs a similar protocol was followed, but three periods of rapid atrial pacing (at various rate between A and B group), 5 minutes in duration each, with 5 minutes of intervening periods at rest heart rate, were induced previous to the coronary occlusion. Results During ischemia and reperfusion the risk area (RA) and necrotic region (NA) were depicted respectively by MCE. Atrial pacing preconditioning significantly reduced the infarct size (NA:RA) in canine hearts compared to control, a further reduction in group B with respect to group A.Conclusions The rapid atrial pacing preconditions the myocardium against ischemia reperfusion injury. The ischemic pacing preconditioning is more effective in limiting infarct size than the preconditioning induced by nonischemic pacing.