Chronic ventricular pacing using an output amplitude of 1.0 volt.
Thirty-seven patients (21 male, 16 female, mean age 71 years) received identical DDD pacemakers. They also received the same bipolar ventricular passive fixation electrode, which has a microporous tip of platinum-iridium, a surface area of 5.8 mm2, and steroid elution. Eighteen months after implantation the ventricular charge threshold [microC] was measured telemetrically at 0.5, 1.0, and 2.0 V, respectively. For the 1.0 and 2.0 V amplitudes the pulse duration was increased until the charge per pulse [microC] was twice the threshold value, thus giving a 100% safety margin in terms of charge ("safety charge"). Patients who had ventricular capture at 0.5 V were permanently programmed to 1.0 V (30/37 patients), while those who did not capture at 0.5 V were set to 2.0 V (7/37 patients). In both cases, the pulse duration was programmed according to the rationale of "safety charge." During a routine follow-up period of 6 months, no complications were observed and none of the patients suffered from symptoms indicating loss of ventricular capture. Twenty-four-hour Holter recordings, obtained from all patients at the end of the follow-up with the output parameters unchanged, revealed constant ventricular capture. In patients with chronic stable pacing thresholds and steroid-eluting low threshold leads who have capture at 0.5 V, chronic ventricular pacing at an output amplitude of 1.0 V is feasible, and it seems to be safe if the pacing threshold is measured as charge delivered per pulse and a 100% safety margin in terms of charge is programmed. Reducing the output amplitude to well below the battery voltage may increase pacemaker longevity.
Schwaab
B
B
Universitätskliniken, Innere Medizin III, Homburg/Saar, Germany.
Schwerdt
H
H
Heisel
A
A
Fröhlig
G
G
Schieffer
H
H
D000368:Aged; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D011211:Electric Power Supplies; D015716:Electrocardiography, Ambulatory; D004567:Electrodes, Implanted; D004867:Equipment Design; D005240:Feasibility Studies; D005260:Female; D005500:Follow-Up Studies; D006327:Heart Block / Q000628:therapy*; D006801:Humans; D008297:Male; D010138:Pacemaker, Artificial; D012804:Sick Sinus Syndrome / Q000628:therapy*; D013686:Telemetry; D013997:Time Factors