Does the location of ectopic ventricular stimulation affect ventricular performance in complete A-V heart block?
In a canine model of complete heart block, the location of ventricular pacing does not significantly affect cardiac output or systemic pressure.
These experiments were designed to determine if the location of ectopic ventricular stimulation influences ventricular performance. Heart block was produced in dogs by ligating the A-V bundle. Small bipolar electrodes were implanted in the apex, high lateral wall, and posterior septal region in six dogs. Several days after recovery dye dilution cardiac outputs, femoral arterial, and right atrial pressures were measured while stimulating from each of the three sites at varying rates between 60 and 240 beats/min. Mean cardiac outputs from stimulation at each of the three sites were similar and their 95% confidence intervals overlapped. Mean systemic pressure did not change significantly with frequency or location of ventricular stimulation. The experiments suggest that the pathway of ventricular activation does not affect ventricular function in complete heart block.
Fletcher et al. (Sun,) studied this question.