Experience with a low profile bipolar, active fixation pacing lead in pediatric patients

Continued miniaturization of permanent pacing systems has promoted use of t his technology in younger and smaller pediatric patients, Intermedics ThinL ine 438-10 active fixation pacing leads (4.5 Fr lead body) were implanted i n 26 patients (17 males/9 females; (9.9) over bar +/- 6.9 years). Twenty of 26 patients received dual chamber systems, 6 of 26 patients single lead sy stems. Each patient has been followed(3) 3 months. Pacemaker analysis at im plant and 6 months later evaluated pulse width thresholds at 2.5 V (atrial <(0.07)over bar> +/- 0.02 vs <(0.13)over bar> +/- 0.02 ms [P = 0.01]; ventr icular <(0.08)over bar> +/- 0.04 ms vs <(0.20)over bar> +/- 0.04 ms [P = 0. 01]); sensing thresholds (atrial 4.1 +/- 0.41 mV vs 4.0 +/- 4.2 mV[P = NS]; ventricular (9.7) over bar +/- 0.72 vs (9.3) over bar +/- 0.94 mV [P = NS] ); and impedance (atrial (345) over bar +/- 12 vs (370) over bar +/- 220 O [P = 0.04]; ventricular 412 +/- 17 vs 458 +/- 190 O [P < 0.01]). One volt l ead failed with exit block at approximately 6 weeks. The youngest (9 months to 5 years) and smallest (6.5-18.0 kg) ten patients have each shown by ven ography to have at least mild venous stenosis at the lead(s) insertion site ; five patients demonstrated collateral formation around asymptomatic obstr uction, with no thrombus formation. The Intermedics 438-10 ThinLine pacing lead has demonstrated good and stable early postimplant electrical paramete rs. Angiographic evaluation in our smaller patients has shown evidence for asymptomatic venous obstruction.