Transcoronary pacing in a porcine model--impact of guidewire insulation.

BACKGROUND: Bradycardia complicating percutaneous coronary intervention (PCI) can require temporary pacing. A transcoronary approach using the guidewire in the coronary artery may be a useful alternative to transvenous pacing. The purpose of the present study was to compare the efficacy of two different coronary guidewires in transcoronary pacing: a novel guidewire (VisionWire®, Biotronik, Germany) which has a coating to electrically insulate the shaft, thereby maximizing current delivery through the intracoronary section compared to a standard guidewire (without insulation) and a standard guidewire/balloon combination. METHODS AND RESULTS: Unipolar transcoronary pacing was performed in 15 pigs under general anesthesia. In each animal, the new VisionWire was compared to a standard floppy guidewire and to a standard floppy guidewire loaded with a standard angioplasty balloon (which provides additional shaft insulation). The coronary guidewire was the cathode and a skin patch electrode (on the anterior or posterior chest wall) was the anode. We examined the effect of different electrode combinations on transcoronary pacing as assessed by threshold and impedance data and the magnitude of the epicardial electrocardiogram. Transcoronary pacing with the bare standard guidewire was effective in 77% of cases using an anterior skin patch electrode and in 87% with a posterior patch at pacing thresholds of 6.7 ± 2.9 V and 4.1 ± 3.0 V, respectively. Loading the same guidewire with an angioplasty balloon increased the pacing efficacy to 100% with significantly lower pacing thresholds of 2.4 ± 1.6 V with an anterior patch and 1.6 ± 1.3 V with a posterior patch (p < 0.001). The bare VisionWire yielded 100% pacing efficacy, with the lowest pacing thresholds of 1.6 ± 0.7 V and 1.0 ± 0.6 V anterior and posterior patch positions, respectively (p < 0.001). In all studies the pacing efficacy was higher and thresholds lower with the skin patch electrode on the posterior chest wall than on the anterior chest wall. CONCLUSIONS: Transcoronary pacing in the animal model is an effective technique. The VisionWire, (even without the additional insulation of a balloon in place) performed better than a standard guidewire (with or without balloon use), and enabled 100% pacing efficacy at acceptable thresholds. Thus, transcoronary pacing, particularly with specific coronary guidewires may be a useful alternative to transvenous pacing during PCI, particularly in the emergency situation when unexpected bradycardias arise during transradial angioplasty when no central venous access is immediately available for transvenous pacing.