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 [μC] 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 [μC] 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.