Cardiac output-based versus empirically programmed AV interval--how different are they?

Aims: To compare empirically programmed and cardiac output-based programming of atrioventricular (AV) interval in patients with dual chamber pacemakers.

Methods And Results: In 19 patients with implanted dual chamber pacemakers due to AV block but otherwise normal hearts, cardiac output was assessed using an impedance cardiography device. In all patients, the AV interval had been previously programmed empirically by an experienced cardiologist. Cardiac output was estimated at AV intervals from 50 to 250 ms during VDD pacing. AV intervals adjusted by serial cardiac output estimations caused a rise in cardiac output in 84% of patients. The maximal achievable cardiac output was greater by 12% +/- 8% (range 0-32%), P < 0.001, than was observed with empirically programmed AV intervals.

Conclusions: In patients with dual chamber pacemakers due to AV block and otherwise normal hearts, empirically selected AV intervals may lead to compromise of cardiac haemodynamics. Optimal AV intervals may be selected by serial cardiac output measurements.