[Chronic stimulation thresholds using carbon and platinum electrodes].

Low-output pacemaker programming depends on the absolute value of the chronic pacing threshold. To assess the chronic threshold with three different types of leads we have used Siemens-Vario pacemakers which allow us to measure the chronic voltage threshold noninvasively. Forty six patients had a 12 mm2 platinum tip lead; 38, 12 mm2 carbon tip lead an 15, 9 mm2 carbon tip lead (Siemens, 414-415, 412 and 423). Platinum leads longevity was 45 +/- 15.9 months; 12 mm2 carbon tip leads, 28 +/- 6.5 and 9 mm2 carbon tip leads, 17 +/- 4.5. Forty two months postimplantation chronic threshold (measured at 0.5 msec pulse-width) was 1.6 +/- 0.6 V for platinum electrodes and 1 +/- 0.3 V for 12 mm2 carbon tip leads (p less than 0.001). Twenty four months postimplantation 9 mm2 carbon electrodes chronic threshold was 1 +/- 0.4 V, and 1.7 +/- 0.5 V for platinum electrodes (p less than 0.001). There were no differences between carbon tip leads with 9 and 12 mm2 pacing area. The new activated carbon tip leads have lower chronic pacing thresholds than platinum electrodes with the same pacing area. Pacemaker-patients with these new type of leads can benefit of reduced output programming and increase their pacemaker longevity.