Premature Ventricular Depolarization

Abstract

Surface "fusion beats", beats with initial and terminal QRS abnormalities, and accompanying secondary ST-T-wave changes appear following intracavitary evidence of premature depolarization. In instances of premature activation of a portion of myocardium, the intracavitary deflection of premature ventricular depolarization may not be apparent in surface leads and, if present, may be reflected in surface leads only by subtle changes in wave configuration that include (1) shortening of the P-R interval, (2) prolongation or amplitude changes or both in the QRS, (3) changes in contour of initial and terminal portion of the QRS, sometimes resembling those of infarction, and (4) secondary ST-T-wave changes. Evidence of electrical asynchronism in a single ventricle and between ventricles is presented.