Experimental study on sudden death due to acute myocardial infarction.

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To Investigate the relatlonshIp between sudden death and the time elapsed after the onset of myocardial infarction and to find a suitable staining method for detection of acute myocardial Infarction, an experimental model of acute myocardial ischemia was made with mongrel dogs by ligating anterior descending branch of left coronary artery. The heart was given electrical simulation at the vulnerable period of the cardiac cycle and the ventricular fibrillation threshold was estimated. Ventricular fibrillation threshold decreased to about 20 % of those of the control hearts 15-30 mm after the coronary artery ligation. Then ii increased with the time elapsed after the coronary ligation and showed almost same values as those of control hearts 4 h after the coronary ligation. The ischemic hearts were fixed with 10 % formalin solution. The sections from the ischemic heart muscle were stained with Luxol Fast Blue (LFB) solution for 24 h and were differentiated for 1-3 min in several changes of 75 % alcohol to a faint dove-colored blue (a newly modified LFB staining). The newly modified LFB staining revealed the myocardial ischemic changes 15-30 min after the coronary ligation. The result suggested that sudden death from ventricular fibrillation is the aptest to occur 15-30 min after the onset of myocardial infarction and the newly modified LFB staining Is useful for detecting such very early myocardial infarction.