Classification of ventricular extrasystoles according to form

Abstract

When studying left anterior and posterior hemiblocks I-3, we learned that whenever posterior wall of left ventricle is activated ahead of anterior one, main QRS forces are directed superiorly and to left; conversely, they are directed inferiorly and to right when anterior wall is activated first. Accordingly, an extrasystole arising front posterior wall of left ventricle should yield, in addition to a right branch block (RBBB) pattern, an AQRS directed superiorly; and, similarly, an extrasystole arising from anterior wall should produce an RBBB pattern, but with an AORS pointing inferiorly. In other words, left ventricular extrasystoles should be expected to generate two completely opposite directions of QRS electrical forces. Thus, all ventricular extrasystoles originating within Purkinje network of anterior of left bundle branch ''t.z or bordering places in ventricular wall, should closely resemble each other, and their electrocardiographic pattern should be that of RBBB with left posterior hemiblock (LPH); and all those originating in Purkinje network of posterior division or within posterior left ventricular wall should also be very similar to each other, but with a pattern of RBBB and left anterior hemiblock (LAH). This proposal undoubtedly introduces a very substantial change in present concept concerning determining factors of place of origin of ventricular extrasystoles. Another substantial change in our concept regarding place of origin of ventricular extrasystoles took place when we could establish that ventricular extrasystoles arising front base of the ventricles generate QRS forces which are