Percutaneous epicardial pacing using a novel insulated multi-electrode lead

Objectives This study hypothesized that shielded electrodes could capture myocardium without extracardiac stimulation. Background Epicardial cardiac resynchronization therapy (CRT) permits unrestricted electrode positioning. However, this therapy requires surgical placement of device leads and risks unwanted phrenic nerve stimulation. Methods In 6 dog and 5 swine experiments, we used a percutaneous approach to access the epicardial surface of the heart and deployed novel leads housing multiple electrodes with selective insulation. Bipolar pacing thresholds at pre-specified sites were tested to compare electrode threshold data, facing both toward and away from the epicardial surface. Results In 151 paired electrode recordings (70 in 6 dogs; 81 in 5 swine), thresholds facing myocardium were lower than those facing away (median threshold of 0.9 [interquartile range (IQR): 0.4 to 1.6] mA vs. 4.6 [IQR: 2.1 to >10.0] mA, respectively, for dogs, p < 0.0001; and 0.5 [IQR: 0.2 to 1.0] mA vs 2.5 [IQR: 0.5 to 6.8] mA, respectively, for swine, p < 0.0001). Myocardial capture was feasible without extracardiac stimulation at all tested sites, with mean ± SE threshold margin of 3.6 ± 0.7 mA at sites of high output extracardiac stimulation (p = 0.004). Conclusions Selective electrode insulation confers directional pacing to a multi-electrode epicardial pacing lead. This device has the potential for a novel percutaneous epicardial resynchronization therapy that permits placement at an optimal pacing site, irrespective of the anatomy of the coronary veins or phrenic nerves.