Assessment of Optimal Atrioventricular Delay Using Doppler Index in Atrioventricular Sequential Pacing

Optimal atrioventricular (AV) delay (AVD) is important for AV sequential pacing. To verify whether optimal AVD can be determined using only Doppler index (DI), adult mongrel dogs with complete AV block were examined with pulsed Doppler echocardiography and hemodynamics measured by a cardiac catheter. After passive-fixation pacing leads were inserted into the right atrium and ventricle, complete AV block was achieved by radio-frequency catheter ablation. AV sequential pacing was then applied. Cardiac index (CI), isovolumic contraction time (ICT), isovolumic relaxation time (IRT), aortic ejection time (ET), and diastolic filling time (DFT) were measured, and DI was calculated as (ICT+IRT)/ET at AVDs of 50, 80, 100, 120, 150, and 200 ms. DI was minimal when AVD was set at 100 ms, and increased significantly when AVD was set at either above or below 100 ms. Optimal AVD determined from DI was the AVD at which DI was minimal. This optimal AVD was equal to the optimal AVD obtained from CI. On the basis of results in this study, DI is useful in determining optimal AVD in AV sequential pacing. (J. Jpn. Coll. Angiol., 2004, 44: 103–107)