Contour of electrically induced premature ventricular beats before and after experimental myocardial infarction in dog.

• Ventricular premature beats represent the commonest arrhythmias in man. Such beats are often present, both in heart disease and in the normal heart, although they occur more frequently in persons with diseased hearts. Because the anatomical site of origin and the direction of spread of premature ventricular systoles cannot be determined on clinical grounds, it is generally agreed that such complexes have no electrocardiographic characteristic findings that point to the presence or absence of underlying cardiac disease. Nevertheless, isolated case reports""' have suggested that premature ventricular systoles may have final 'ventricular deflections characteristic of acute myocardial infarction. Recent clinical, analyses""" also suggested that bizarre forms of depolarization and of repolarization of premature ventricular systoles are almost exclusively found in persons who have underlying myocardial disease.