Acute and Chronic Performance Evaluation of a Novel Epicardial Pacing Lead Placed by Percutaneous Subxiphoid Approach in a Canine Model

Abstract

Background - Endovascularly implanted leads risk vascular injury and endocarditis, and can be difficult to locate in desired positions for LV pacing. We evaluated the acute and long-term stability, electric performance and histopathology of a percutaneously placed intrapericardial lead (IPL). Methods and Results - Twelve adult mongrel dogs underwent defibrillator implants incorporating IPLs. Successful uncomplicated percutaneous implantation of an IPL was achieved in all. Early fluoroscopic shift noted with 3 of 6 of the initial version IPL-1 was not seen with the modified IPL-2. Mean±95% confidence interval bipolar capture threshold at 0.5-ms pulse width for the IPL increased from 0.69±0.14 V at implant to 1.50±0.34 V (P=0.003) at 12 weeks. The 12-week thresholds were higher for IPL compared with right ventricular endocardial leads (0.75±0.33 V; P=0.001) but not different compared with coronary sinus leads (1.33±0.58 V; P=0.994). IPL impedance increased from 742±46 Ω at implant to 1066±207 Ω at 12 weeks (P=0.007). R-wave amplitude at 12 weeks was 8.37±1.52 mV. There was no important phrenic nerve stimulation from IPL pacing. Histopathology in 8 animals showed adequate adhesion of the electrodes or mesh to the epicardium without damage to underlying vasculature. There was no evidence for late pericardial inflammation or effusion. Conclusions - The IPL demonstrated adequate stability of position and acceptable electric parameters without chronic pericardial inflammation in this canine model and offers a potential alternative to endocardial pacing leads.