Left Axis Deviation in Inferior Infarction; Vectorcardiographic Recognition of Concomitant Left Anterior Hemiblock

The vectorcardiograms of 30 patients with inferior infarction and abnormal left axis deviation were studied. In 23 cases, the frontal plane loop was clockwise rotated and the initial vectors were superiorly displaced. The remaining seven tracings also showed superior orientation and clockwise rotation of the initial forces, but the second half of QRS was displaced further superiorly and counterclockwise inscribed. The vectorcardiographic pattern observed in those seven cases was postulated to indicate inferior wall infarction with concomitant left anterior hemiblock. This hypothesis was substantiated by the clinical observation of two patients in whom the separate components of the complete pattern appeared successively. It is concluded that in inferior infarction, abnormal left axis deviation may result either from the infarction alone, or from the concomitant presence of left anterior hemiblock which can be depicted from observation of the frontal plane vectorcardiogram.