Feasibility of customised unipolar conversion using bipolar temporary pacing wires in patients after surgical repair of congenital heart disease

Objective: Temporary pacing wires play a crucial role in the diagnosis and therapy of post-operative arrhythmia after surgery for congenital heart disease. At present, bipolar pacing wires are used in most institutions. In case of functional failure of these wires, a unipolar mode of stimulation and sensing should be theoretically possible as a rescue procedure. Methods: We tested the feasibility of the customised unipolar mode in 18 post-operative patients with congenital heart disease (age 9.2 ± 13.9 months, weight 6.3 ± 3.8 kg, and cardiopulmonary bypass time 70 ± 29 minutes). As there are two possible unipolar configurations, there are twice the number of testing parameters; of those, we compared sensing (mV) and pacing thresholds (V at 0.5 ms). Results: Atrial sensing was significantly better in the unipolar modes (p < 0.001, p < 0.003). The ventricular unipolar sensing did not differ significantly in the better of the two possible configurations from the bipolar values (p = 0.363). For the unipolar pacing thresholds, only the better unipolar configuration did not differ significantly from the bipolar measurements (atrial: p = 0.058, ventricular: p = 0.138). There was no exit block or undersensing. Conclusion: The results demonstrate that unipolar stimulation and sensing using bipolar epicardial temporary pacing wires is feasible. In the case of failure of bipolar temporary pacing wires, this modality represents an easy rescue measure that in such cases should always be considered.