PO-04-041 EFFICACY OF BALLOON EXPANDABLE EXTREME-LOW TEMPERATURE "XLT" VENTRICULAR EPICARDIAL CRYOABLATION: A PRE-CLINICAL DOSE RANGING STUDY

Abstract

Lack of transmural lesion formation with catheter or surgical ablation for ventricular tachycardia (VT) can be an important determinant of arrhythmia recurrence. The aim of this study was to evaluate the feasibility and efficacy of a novel balloon expandable extreme-low temperature (XLT) cryoablation device for epicardial ventricular ablation. A total of six healthy Yorkshire swine (63 ± 6 kg) underwent surgical epicardial access. Four-to-five right (RV) and left (LV) ventricular epicardial targets were identified: anterior (1-2), lateral (1-2), summit (1-2). Ablation was performed with the novel 'XLT-cryo' device (HeartPad®Mini, Corfigo, Montclair, NJ), a balloon-expandable epicardial device that circulates extremely cold helium (∼ -253C) at a high flow rate through a flat pad with dimensions of ∼15 x 15mm. It is mounted onto the surface of an ∼30mm insulation balloon with blunted ends for fixation and parietal pericardial protection. At the end of each timed ablation, a thaw cycle was initiated to warm the device and allow repositioning to the next target. Ablation lesion size was measured using TTC staining. A total of 27 epicardial lesions were created (RV: n=2; LV: n = 25). The average lesion depth increased with time and reached complete transmurality with a plateau at 1 minute (time [T; sec] and mean depth±stdv [mm]; T15=11±0.5, T30=12±1, T60=15±1, T120=16±0.5, T240=17±0.5; Figure). Lesion transmurality was achieved in all lesions with ablation time ≥2 min. Lesion geometry was similar across different RV/LV locations, including the LV summit. Ventricular fibrillation (which is common in Yorkshire swine) occurred during/following 3 applications out of 27. Our results indicate that epicardial cryoablation using the novel balloon expandable HeartPad® device with extremely low temperature applications can efficiently produce transmural ventricular lesions in different epicardial locations. This technology holds potential for both surgical and catheter-based VT ablation in humans.