Efficacy of Balloon Expandable Extreme-Low Temperature Ventricular Epicardial Cryoablation: A Preclinical Proof of Concept Evaluation.

Background: Current epicardial ablation technologies are limited by the inability to create adequate depth lesions and risk of collateral injury to extracardiac structures.

Objective: To evaluate the feasibility and efficacy of ventricular epicardial ablation with a novel balloon-expandable extreme-low temperature (XLT) cryoablation catheter with an embedded insulation pontoon for protection of extracardiac structures which has been specifically designed for epicardial ablation.

Methods: 10 healthy swine underwent surgical (6) and subxiphoid percutaneous (4) epicardial access respectively. A total of 3-6 sites were targeted in the right and left ventricular wall for different exposure durations. Ablation was performed with a large footprint (surgical) and smaller footprint (percutaneous) version of the HeartPad® (Corfigo Inc., Montclair, NJ) XLT system. The system consists of the balloon-expandable cryoablation catheter and a console. The console vaporizes liquid helium (-269˚C) and controls continuous delivery of extremely cold helium gas at high flow rates through a high-efficiency ablation element mounted on an expandable insulation pontoon to protect extracardiac structures. Ablation lesions were assessed by gross pathology and histological examination.

Results: A total of 42 epicardial lesions were created. The mean lesion depth increased progressively with the ablation time (surgical catheter: 11±2 mm at ≤30 seconds, 13±4 mm at 60 seconds, 15±3 mm at ≥120 seconds, P =0.001; percutaneous catheter: 10±2 mm at 30 seconds, 14±2 mm at 60 seconds, 16±2 mm at 120 seconds], P =0.001). Lesion geometry appeared unaffected by presence and thickness of epicardial fat. One episode of ventricular fibrillation occurred following ablation over the atrioventricular groove and 2 adjacent obtuse marginal arteries.

Conclusion: Surgical or percutaneous epicardial ablation using the HeartPad® XLT cryoablation system is feasible and can efficiently produce deep ventricular lesions in different epicardial locations.