Typical and Atypical Electrocardiograms in Myocardial Infarction Caused by Acute Coronary Occlusion and Coronary Insufficiency

Abstract

When an acute coronary episode occurs, if the initial electrocardiogram does not indicate a coronary occlusion, it may be difficult at first to determine the exact nature of the attack. The electrocardiogram may remain normal for a variable period or may indicate coronary insufficiency and myocardial ischemia. In the cases going on to coronary thrombosis and massive infarction, the electrocardiogram may show various rapidly changing patterns before the appearance of RS-T elevation and Q-waves. In coronary occlusion the electrocardiogram often shows involvement of more than one surface and variations of the typical patterns are frequent. The changes may be present in only a few of the 12 routine leads or only in special chest positions. In an acute coronary episode it is essential to keep the patient at rest until the extent of myocardial involvement has been determined. Not infrequently the electrocardiogram shows temporary improvement or actual return of RS-T and T to normal between the third and 10th days following myocardial infarction.