When there is not only anterior ST segment elevation (V3 and V4), but also septal (V1 and V2) and lateral (V5, V6, lead I and lead aVL), an “extensive anterior” MI is said to be present.

This can be a congenital anomaly or acquired as a complication of a myocardial infarction. Ventricular septal defects are classified as membranous, perimembranous, supracristal (infundibular or ...