Electrocardiogram and vectorcardiogram reconstruction and its application to clinical diagnosis of myocardial infarction

Abstract

1. 1. Electrocardiograms and vectorcardiograms in old and fresh myocardial infarctions of anteroseptal, anterolateral, anteroposterior, lateral, posterolateral, and posterior positions were obtained by means of the authors' reconstruction method. 2. 2. Characteristics of the electrocardiographic and the vectorcardiographic changes in old and fresh myocardial infarctions of these positions were described. 3. 3. Changes in the electrocardiograms and the vectorcardiograms closely resembled those reported by previous investigators. 4. 4. In general, RS-T elevations in fresh infarctions corresponded to Q phenomena or to reduced R waves in old myocardial infarctions; and RS-T depressions in fresh infarctions corresponded to augmentation of R waves in old myocardial infarctions. 5. 5. Displacement of QRS loops directed away from the infarcted area in old myocardial infarctions and displacement of RS-T junctions directed toward the infarcted area in fresh infarctions were the typical changes. These changes were more pronounced in the polyogram than in the vectorcardiograms using the Grishman system. 6. 6. When right bundle branch block was artificially complicated, the Q wave in the lead over the infarcted area in uncomplicated myocardial infarction also appeared distinctly in the leads over the infarcted area. Extremity lead electrocardiograms varied with location and extent of the infarcted area, and every type of right bundle branch block appeared, i.e., the usual and the unusual types of Wilson block and the rare type of bundle branch block. 7. 7. When right bundle branch block was artificially complicated, the initial portion of the QRS loop of the vectorcardiogram was displaced away from the infarcted area, but the terminal portion was scarcely displaced at all in most of the left ventricular myocardial infarctions, and was always inscribed anteriorly to the right. 8. 8. When left bundle branch block was artificially complicated, the Q-wave characteristic of myocardial infarction failed to occur in the leads over the infarcted area, so that diagnosis of myocardial infarction complicated by left bundle branch block was usually very difficult. QRS loops in the vectorcardiogram were not remarkably altered by complication of left bundle branch block. Only the mid-portion of the QRS loop was slightly displaced away from the infarcted area in most cases.