A novel approach for transcoronary pacing in a porcine model

Transcoronary pacing for the treatment of bradycardias during percutaneous coronary intervention (PCI) is a useful technique in interventional cardiology. The standard technique is unipolar pacing with the guidewire in the coronary artery against a cutaneous patch electrode. We developed a novel approach for transcoronary pacing by using intravascular electrodes in different positions in the aorta in a porcine model.

Unipolar transcoronary pacing was applied in 8 pigs under general anesthesia using a standard floppy guidewire in a coronary artery as the cathode with additional insulation of the guidewire by a monorail angioplasty balloon. Intravascular electrodes positioned in the aorta thoracalis and the aorta abdominalis served as indifferent anodes. The efficacy of transcoronary pacing with intravascular anodal electrodes was assessed by measurement of threshold and impedance data and the magnitude of the epicardial electrogram in comparison to unipolar transvenous pacing using the same indifferent anodal electrodes. Transcoronary pacing with the guidewire-balloon combination using indifferent intravascular electrodes was effective in all cases. Transcoronary pacing thresholds obtained against the indifferent coil electrodes in the aorta thoracalis (0.8 ± 0.5 V) and in the aorta abdominalis (0.8 ± 0.5 V) were similar to those obtained with unipolar transvenous pacing (0.7 ± 0.3 V and 0.6 ± 0.2 V, respectively), whereas the tip-electrode in the aorta thoracalis serving as indifferent anode produced significantly higher pacing thresholds (guidewire, 2.8 ± 2.6 V; transvenous lead, 1.5 ± 0.8 V). The lower pacing threshold of the coil-electrodes was associated with significantly lower impedance values (aorta thoracalis, 285 ± 63 ohm; aorta abdominalis, 294 ± 61 ohm) as compared to the tip-electrode in the aorta thoracalis (718 ± 254 ohm). The amplitude of the epicardial electrogram acquired by the intracoronary guidewire was without significant differences between the indifferent electrodes.

Transcoronary pacing in the animal model using a standard guidewire with balloon insulation and intravascular indifferent electrodes is depending on the optimal configuration of the anodal electrode. The use of intravascular coil electrodes with a sufficient surface area can produce 100% capture at thresholds comparable to transvenous pacing. Therefore, technical integration of these coil electrodes into the access sheath or the guiding catheter with respect to handling these tools in daily clinical practice in the catheterization laboratory could further facilitate the transcoronary pacing approach.