Does biventricular or left ventricular pacing improve cardiac haemodynamics compared to right ventricular pacing in patients immediately after aortic valve replacement?
Biventricular pacing increases the force of left ventricular contraction at the onset of systole compared to right ventricular pacing alone, demonstrating the haemodynamic benefit of more synchronous contraction.
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 consis- tently 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 an increasedforce by the left ventricle at the onset of systole during biventricular pacing, resulting from a more synchronous contraction, and shows that such changes may occur in the absence of any alteration in the external work done by the left ventricle.
Gibson et al. (Sat,) studied this question.