Introduction: Shocks of implantable cardioverter-defibrillator are painful because defibrillation shock stimulates also nerves and skeletal muscles around the heart. We have developed an epicardial defibrillation lead with isolation towards extracardial structures allowing defibrillation with limitation of defibrillation discharge influence.
Methods: Three acute experiments were carried out in porcine model. Two steerable 24F sheaths were introduced into the pericardial space by percutaneous, subxifoideal approach. Two partially insulated defibrillation coils were introduced under fluoroscopic control on the epicardial surface of the right and left ventricles. Ventricular fibrillation (VF) was induced by electrical stimulation and defibrillation shock was delivered via a biphasic waveform between active surface of the coils. The intervals between the individual discharges were at least 3 minutes.
Results: A total of 114 defibrillation shocks were applied without damaging defibrillation system. Lowest energy required to restore sinus rhythm was 9.3 ± 7.5 Joules. Average defibrillation threshold (?3 successful separate attempts at a single energy dose) was 13.3 ± 9.2 Joules, lower limit was 5 Joules. Coil resistance varied only slightly (51-72 Ohms). At necropsy, no evidence of significant myocardial or coronary injury, hemorrhage, or trauma of extra-pericardial structures was noted.
Conclusions: A new prototype of epicardial defibrillation system was proven to be reliable, efficient and workable even after more than 100 defibrillation shocks. These pilot data indicate the possibility of developing a new, efficient and potentially less painful defibrillation system.