 an isolated ventricular endocardial preparation removed from canine hearts one to two days after coronary artery occlusion and superfused in vitro is described . 
 the alteration in electrophysiological characteristics of subendocardial purkinje fibers surviving in infarcted regions and the relationship of these changes to the generation of ventricular arrhythmias is discussed . 
 the advantages of such preparations for assessing the mechanism of action of antiarrhythmic drugs in post - infarction ventricular arrhythmias is discussed.imagesfigure 2 . 
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