A Novel Defibrillation Tool: Percutaneously Delivered, Partially Insulated Epicardial Defibrillation.

Introduction: Epicardial defibrillation systems currently require surgical access. We aimed to develop a percutaneous defibrillation system with partially-insulated epicardial coils to focus electrical energy on the myocardium and prevent or minimize extra-cardiac stimulation.

Methods: We tested 2 prototypes created for percutaneous introduction into the pericardial space via a steerable sheath. This included a partially-insulated defibrillation coil and a defibrillation mesh with a urethane balloon acting as an insulator to the face of the mesh not in contact with the epicardium. The average energy associated with a chance of successful defibrillation 75% of the time (ED75) was calculated for each experiment.

Results: Of 16 animal experiments, 3 pig experiments had malfunctioning mesh prototypes such that results were unreliable; these were excluded. Therefore, 13 animal experiments were analyzed - 6 canines (29.8±4.0kg); 7 pigs (41.1±4.4kg). The overall ED75 was 12.8±6.7J (10.9±9.1J for canines; 14.4±3.9J in pigs [P=0.37]). The lowest ED75 obtained in canines was 2.5J while in pigs it was 9.5J. The lowest energy resulting in successful defibrillation was 2J in canines and 5J in pigs. There was no evidence of coronary vessel injury or trauma to extra-pericardial structures.

Conclusion: Percutaneous, epicardial defibrillation using a partially insulated coil is feasible and appears to be associated with low defibrillation thresholds. Focusing insulation may limit extra-cardiac stimulation and potentially lower energy requirements for efficient defibrillation.