Remarks on the Graphic Diagnosis of Coronary Disease

Abstract

I . Typical and Atypical Electrocardiograms in Myocardial Infarction Caused by Acute Coronaqj Occlusion and Coronary Insufficiency The electrocardiogram has been epic making in the diagnosis of coronary occlusion and is the main reason for the ever increasing frequency with which this disease is detected. The ordinary electrocardiographic diagnosis has become so well-recognized that i t is now well to talk, not only of the typical electrocardiogram, but of the atypical electrocardiogram in myocardial infarction. I t is time also to divide the study of myocardial infarction into two types, (1) the subendocardial type, secondary to coronary insufficiency, that is, without complete occlusion of a coronary artery, (2) the through-and-through type caused by coronary occlusion, that is, complete obstruction of a coronary artery. Coronary insufficiency is usually associated with coronary sclerosis but may be observed in a normal heart, for example, following hemorrhage. In coronary insufficiency the electrocardiogram shows RS-T depression, T-wave inversion, or RS-T depression and T-wave inversion combined, since the damage is localized in the subendocardial region. For the same reason, the outlobk is much better in coronary insufficiency. The electrocardiographic alterations are usually transient, lasting a day or two, or one or two weeks or months ; rarely they are permanent. The T-wave inversions are not usually as deep as those seen in coronary occlusion. There are no Q-waves or RS-T segment elevations because there is no through-and-through infarction. I t may take a few days for the electrocardiographic changes to develop; hence, if an acute coronary episode of any kind is suspected the electrocardiogram should be repeated several times. The type of electrocardiogram just described, that is, with RS-T depressions and T-wave inversions, but without deep Q-waves, is also seen in the premonitory phase of a coronary occlusion. Obviously there is a partial occlusion which causes coronary insufficiency. I believe that, once the artery is completely occluded, the clinical and electrocardiographic picture of coronary occlusion appears, that is, RS-T elevation is seen immediately. Within the first 12 to 24 hours the characteristic deep Q-wave is not seen but one can almost discern i t if he looks intently. After 12 to 24 hours i t is usually quite obvious. In anterior wall infarction the deep Q and RS-T elevations appear in leads I, aVL and in chest leads. In diaphragmatic or inferior wall infarction these alterations appear in leads 11, I11 and aVF. In true posterior infarction, tall R-waves appear on the right side of the chest, i. e., in V1 and 2. Q-waves may be seen in Va, s, 7 or Vs. Doctor Jaffe has been in the forefront in the description of atypical changes in coronary occlusion. For example, in serial electrocardiograms, temporary improvement may occur.