ONE-YEAR FOLLOW-UP OF SINGLE-LEAD DDD STIMULATION USING THE OLBI PRINCIPLE

A new pacing mode which significantly reduced atrial pacing threshold, the 'overlapping biphasic impulse' (OLBI) stimulation using the float ing atrial dipole of a single-pass lead has been reported. In this stu dy the performance of OLBI stimulation was evaluated up to one year fo llow-up. In 10 patients (5 men, 5 female, age 63+/- 13 years) with com plete AV block, single-lead VDD systems with an additional atrial OLBI stimulation capability were implanted. Temporary atrial OLBI pacing a nd diaphragmatic stimulation thresholds, P and R wave amplitudes, lead impedance and ventricular pacing thresholds were determined during im plantation, before hospital discharge and at 1, 3, 6, and 12 month fol low-up. The mean atrial OLBI pacing threshold decreased significantly at 1 year follow-up with respect to the implantation and the hospital discharge values (2.1 +/- 0.5 V vs 2.6 +/- 0.7 V and 2.8 +/- 0.8 V, p< 0.05). While five patients did not experience any diaphragmatic stimul ation at the maximum atrial pacing voltage (4.8V) of Dromos SL M7 pace maker during one year follow-up, the other five patients had a mean di aphragmatic stimulation threshold of 3.1 +/- 0.8 V. In two patients th e atrial pacing threshold was close to the diaphragmatic stimulation t hreshold, so safe programming was possible in 8 (80%) patients. In con clusion, the OLBI configuration provides AV-synchronous dual chamber p acing with a single-pass lead also in long-term.