The utility of transvenous pacing, despite its advantages, has been limited in small subjects. The purpose of this study was to evaluate the effectiveness of transvenous chronic pacing in a rabbit model. Seven rabbits weighing 4.3 to 5.4 kg (mean 4.8 kg) underwent permanent pacemaker system implantation using a novel, custom transvenous pacing lead and adapter from Medtronic to connect to a standard pacemaker generator. Rabbits underwent general anesthesia, and a 5 French hemostatic sheath was placed into the right jugular vein via cutdown. Under fluoroscopic guidance, the lead was placed and fixed at the desired position in the right ventricle through a custom 5 French guider. After documentation of appropriate pacing and sensing thresholds, the sheath and guider were removed, and the pacing electrode was secured to the neck fascia with sutures and a custom tie-down sleeve. The remainder of the lead was subcutaneously tunneled to the back of the neck where the generator was connected and fastened through a second incision. Surgical recovery required 1-2 days. All animals were paced at 340 beats per minute for 25 ± 4 days without pacing complications. Capture was documented weekly by electrocardiographic and/or physical examination. Rapid transvenous pacing achieved congestive heart failure confirmed by nuclear studies in all animals.

CONCLUSIONS: This technique demonstrates that transvenous pacing can be effectively performed in small animals with minimal complications, relatively quick recovery, and appropriate chronic pacing thresholds. This technique avoids unnecessary risks associated with thoracotomy and epicardial lead placement, and may have important clinical implications for pacing in infants.