Effect of changes in ventricular activation on cardiac haemodynamics in man. Comparison of right ventricular, left ventricular, and simultaneous pacing of both ventricles.

To investigate the influence of changes in activation on left ventricular ejection, the effects of right ventricular, left ventricular, and simultaneous pacing of both ventricles were studied in 6 patients immediately after replacement of the aortic valve with a Starr-Edwards prosthesis. Variation in pacing site caused little or no change in systemic arterial pressure or cardiac output. However, the rate of movement of the ball of the prosthesis at the onset of left ventricular ejection was consistently greater during biventricular pacing than during pacing of the right ventricle alone, with intermediate values during left ventricular pacing. This provides evidence for the development of