Single lead VDD pacing in children with complete heart block

OBJECTIVE: To evaluate clinically transvenous single lead VDD pacing in children with complete heart block. DESIGN: Case series. SETTING: Tertiary care unit of a pediatric teaching hospital. PATIENTS: Consecutive sample of children with complete heart block requiring pacing and meeting the criteria for VDD pacing. INTERVENTIONS: VDD single lead pacing systems (Thera VDD 8948 generator, Capsure VDD 5032 single pass lead) were implanted in nine children (mean age 10.7 years, 95% CI 8.9 to 12.3). All patients were reviewed six weeks and six months post-implantation with clinical review, detailed pacemaker interrogation, optimal device programming, treadmill exercise resting, 24 h Holter monitoring and echocardiography. RESULTS: Mean procedure time was 62.5 mins (CI 52 to 73), mean fluoroscopy time 3.8 mins (CI 2.4 to 5.1) and mean P wave sensing amplitude 2.75 mV (CI 2.5 to 3), without significant decrease during Valsalva manoeuvre (mean 2.4 mV, CI 2.2 to 2.8). Low pacing thresholds of mean amplitude 0.39 V (CI 0.38 to 0.4) were established at pulse width 0.5 ms. Two patients required early revision - one lead dislodged and one patient had a loose set screw. Follow-up showed satisfactory pacemaker function, and mean percentage atrioventricular (AV) synchronous pacing 96.8% (CI 93 to 99) at six weeks and 97% (CI 95 to 99) at six months. P wave sensing failures were less than 1%. AV synchronous pacing was maintained for more than 99% of the period of treadmill exercise testing. There was a significant mean increase in cardiac output of 24% (CI 8 to 40, P<0.05) at rest in VDD mode compared with VVIR mode. CONCLUSIONS: Single lead VDD pacing is an effective and reliable method of 'physiological' race responsive AV synchronous pacing in children with complete heart block and should be considered a viable alternative to dual lead pacing systems.