[Influence of atrioventricular delay of dual chamber pacemaker on cardiac function: evaluation by tissue Doppler echocardiography].

OBJECTIVE

To investigate the optimal atrioventricular delay (AVD) in using dual-chamber pacemaker.

METHODS

Thirty patients with atrioventricular conduction block, aged 62 +/- 12, implanted for were implanted with DDD pacemakers. Program controller was used to program the AVD. Two-dimensional echocardiography was used to measure the hemodynamic parameters: cardiac output (CO), cardiac output index (CI), stroke volume (SV), left ventricular ejection fraction (LVEF), left ventricular end-systolic diameter (LVESd), left ventricular end-diastolic diameter (LVEDd), peak systolic velocity (Vs), and peak systolic time of the basic segment at inter-ventricular septum and left ventricular under the pattern of tissue velocity imaging at different values of AVD. For each patient, the AVD was prolonged to 250 ms stepwise by 30 ms starting from 100 ms.

RESULTS

Cardiac function changed with different AVD. When the AVD was 160 ms, the maximal values were reached for CO (5.5 L/min+/-1.1 L/min, P<0.05), CI (3.5 Lxmin(-1)xm(-2)+/-0.8 Lxmin(-1)xm(-2), P<0.05), SV (78 ml+/-13 ml, P<0.05), LVEF (67%+/-7%, P<0.05), LVEDd (121 mm+/-29 mm, P<0.05), and Vs. LVESd reached its minimal value (37 mm+/-16 mm, P<0.05) and the Vs values of different ventricular walls reached the minimal too (all P<0.05).

CONCLUSION

When the optimal AVD is selected the cardiac function can be significantly improved. Tissue Doppler echocardiography is useful in evaluating cardiac function and determining the optimal AVD.