Cardiac Index and Exercise during VDD/DDD versus VVIR Pacing in Children

Abstract

Twelve children with a VDD/DDD pacemaker during 100, 125, 150, 200 ms atrioventricular delays and VVIR pacing, cardiac index was measured at rest and evaluated by endurance time during exercise stress test. The optimal atrioventricular delay, which provides highest cardiac index, was 100 ms in three, 125 ms in two, and 150 ms in four and 200 ms in three patients. VDD/DDD pacing with different atrioventricular intervals resulted in a significantly higher cardiac index (6.70 ± 3.06, 6.49 ± 2.51, 6.15 ± 2.35, 6.37 ± 2.69 l/min/m², respectively) than VVIR pacing (5.25 ± 2.39 l/min/m²) at the rest. However, endurance times to treadmill exercise were similar in both the optimal atrioventricular delay (21.6 ± 3.7 min) and VVIR mode (22.4 ± 3.4 min) (p > 0.05).