BACKGROUND Despite advances in reperfusion times, patients presenting with acute myocardial infarction carry an unacceptably high rate of mortality and morbidity. Mechanical unloading of the left ventricle (LV) has been suggested to reduce infarct size after acute myocardial infarction. Although prior studies have investigated LV unloading during ischemia with a delay in reperfusion, little is known about the optimal timing for LV unloading in the setting of acute myocardial infarction. METHODS Studies were conducted in 17 adult Yorkshire swine weighing 67±5 kg. A coronary balloon was inflated in the mid left anterior descending for 60 minutes to induce a myocardial infarction. The coronary balloon was then deflated for 120 minutes (reperfusion). The animals were stratified into 3 groups: group 1 (control, reperfusion with no LV unloading, n=5), group 2 (LV unloading during ischemia with delayed reperfusion, n=6), and group 3 (simultaneous LV unloading and reperfusion, n=6). Staining the hearts with Evans blue and 2,3,5-triphenyltetrazolium chloride was used to identify the area at risk and the infarct area respectively. Infarct percent size was defined as the area of infarcted myocardium divided by the area at risk. RESULTS Of the 3 groups, group 3 demonstrated significantly smaller infarct percent size compared with controls (54.7±20.3% versus 22.2±13.4%; P=0.03). Comparison between group 1 and group 2 did not reveal significant difference (54.7±20.3% versus 43.3±24.6%; P=0.19). CONCLUSIONS In our large animal experimental model, simultaneous reperfusion and mechanical LV unloading yielded the smallest infarct size compared with no LV unloading or LV unloading with delayed reperfusion. In the context of prior studies showing benefit to unloading before reperfusion, these findings raise questions about how this strategy may be translated to humans.

中文翻译：

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同时进行再灌注的经皮机械卸载在实验性急性心肌梗死中引起心肌抢救的增加。

背景技术尽管再灌注时间有所进步，但患有急性心肌梗塞的患者的死亡率和发病率却高得令人无法接受。已建议机械卸载左心室以减轻急性心肌梗塞后的梗塞面积。尽管先前的研究已经研究了缺血期间左心室卸载的再灌注延迟，但是对于急性心肌梗死时左心室卸载的最佳时机知之甚少。方法在17只重约67±5千克的成年约克夏猪中进行了研究。在左中前降支中将冠状动脉球囊充气60分钟，以诱发心肌梗塞。然后将冠状动脉球囊放气120分钟（再灌注）。将动物分为3组：第1组（对照组，无LV卸载的再灌注，n = 5），第2组（局部缺血再灌注延迟缺血后左室卸载，n = 6），第3组（同时左室卸载和再灌注，n = 6）。用伊文思蓝和2,3,5-三苯基四唑氯化物对心脏进行染色，分别确定危险区域和梗塞区域。梗塞百分比大小定义为梗塞心肌面积除以危险面积。结果在3组中，第3组的梗塞百分比明显低于对照组（54.7±20.3％对22.2±13.4％； P = 0.03）。第1组和第2组之间的比较没有显示显着差异（54.7±20.3％和43.3±24.6％； P = 0.19）。结论在我们的大型动物实验模型中，同时进行再灌注和机械性左心室卸载可产生最小的梗塞面积，而无左心室卸载或有延迟再灌注的左心室卸载则更为明显。在先前的研究表明对再灌注前进行卸载有益的背景下，这些发现提出了有关如何将该策略转化为人类的疑问。