Differences in the Changing Trends of Monophasic Action Potential Duration and Effective Refractory Period of the Ventricular Myocardium After Myocardial Infarction in Vivo

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Background The relationship between monophasic action potential duration (MAPD) and effective refractory period (ERP) is poorly understood after myocardial infarction (MI) in vivo. Methods and Results Forty rabbits were randomized into either a sham operation (SO) group (n=10) or MI group (n=30), both of which underwent thoracotomy, but the left anterior descending coronary artery was occluded in the MI group only. The MAPD and ERP of the endocardial, midmyocardial and epicardial cells of the infarction zone were observed at baseline, 2 days after thoracotomy and then 5min, 15min, 30min, 2 days, 14 days and 60 days after coronary occlusion (CO). At baseline, ERP correlated strongly with MAPD_<90>. During the 5-30 min after CO, both MAPD_<90> and ERP of the 3 layers of the myocardium shortened markedly (eg, MAPD_<90> Mid was approximately 50% of the baseline value at 5 min after CO). MAPD_<90> and ERP recovered gradually over the 2-60 days after MI. ERPMid exceeded MAPD_<90> Mid and the post repolarization refractoriness phenomenon appeared during the 5-30 min after CO. Conclusions The different changing trends of the MAPD and ERP of the mid-myocardial cells may underlie the arrhythmias that occur after MI.
社団法人日本循環器学会の論文
2004-11-20