Etiology of Ventricular Arrhythmias in the Early Phase of Myocardial Ischemia

Abstract

Since the work of Harris and coworkers it has been common knowledge that ventricular arrhythmias after coronary artery occlusion in animal experiments occur in two distinct phases [1, 2]. The first one corresponding to the acute phase of ischemia, will last until 15–30 min after coronary occlusion, the second phase will start after 4–8 h and last for 24–48 h. Exact figures of the incidence of ventricular arrhythmias in the early phase are sparse, but in a large series of 351 dogs in which complete occlusion of a major coronary artery was performed, ventricular fibrillation occurred in 28% of the animals in the first 30 min [3]. Our own experience with isolated perfused hearts of pigs and dogs, driven at a constant rate just above the sinus rate, in which the left anterior descending artery was occluded, indicates that ventricular premature beats occur in 72% of cases, ventricular tachycardia (more than five consecutive ectopic beats) in 45% and ventricular fibrillation in 32% of cases, all within 2–8 min after occlusion [4]. It is not known whether a bimodal distribution of ventricular arrhythmias in myocardial infarction in man exists, but the early arrhythmia phase in the animal model may be related to the ‘prehospital’ phase of arrhythmias in human infarction. The incidence of ventricular arrhythmias in the first hours of myocardial infarction in man varies widely in different reports, but figures approximating 70% for ventricular premature beats, 40% for ventricular tachycardia, and 30% for ventricular fibrillation have been reported [5, 6].KeywordsVentricular TachycardiaLeft Anterior DescendRest Membrane PotentialCoronary OcclusionCoronary Artery OcclusionThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.