Effects of atrial and ventricular tachycardias on the cardiovascular dynamics

Abstract

In anesthetized dogs, the effects of tachycardia on the cardiovascular dynamics were studied. It was observed that atrial and ventricular tachycardias decrease mean arterial pressure, stroke volume, cardiac output, and regional arterial blood flows, and depress ventricular function curves. Moreover, the tachycardias increase myocardial contractile force, pulmonary arterial pressure, left and right atrial pressures, and total pulmonary and regional peripheral resistances. The magnitude of these hemodynamic changes observed in atrial or ventricular tachycardia of the same focus increases in proportion to increases in heart rate. Furthermore, the magnitude of the hemodynamic changes observed in ventricular tachycardia of a given rate is much greater than that observed in atrial tachycardia of an equivalent rate. The mechanisms responsible for the hemodynamic changes observed in tachycardia are discussed.