Significance of the atrial contribution to ventricular filling

The contributions of atrial systole to ventricular filling are emphasized by analyses of pressure curve data in (1) patients with complete heart block studied by right and left heart catheterization, (2) patients with sinus rhythm and atrial fibrillation and (3) sinus rhythm and ventricular premature beats. The level of systolic and diastolic right and left heart pressures varies with the temporal relation between the P and QRS complexes in patients with complete heart block. Peak pressures are recorded when there is a normal temporal relation between the P and QRS complexes. The rate of rise of the systemic arterial pressure curve is also at a maximum when the normal P-QRS relation is maintained. Comparison of left ventricular and systemic arterial pressures during sinus rhythm and ventricular premature beats demonstrates higher systolic peak pressures during sinus rhythm with normal atrioventricular conduction; of equal importance is the observation that left ventricular end-diastolic pressures are higher during sinus rhythm than during a series of ventricular premature beats. One subject was studied during both atrial fibrillation and normal sinus rhythm in the course of left heart catheterization. Left ventricular. systolic and end-diastolic pressures were higher during normal sinus rhythm than during atrial fibrillation. The development of mitral regurgitation during ectopic ventricular beats is also illustrated. These data demonstrate the physiologic importance of maintaining the normal temporal sequence of atrioventricular activity.