Abstract 3100: Safety and Efficacy of Transcatheter Epicardial Cryoablation - Comparison of the Lesion Size between Extra-Large Tip and Large Tip Catheter
Usefulness of the percutaneous transcatheter epicardial radiofrequency ablation (RFA) for ventricular tachycardia (VT) originating from epicardial site has been reported. However, epicardial lesion size by RFA is limited because of no convective cooling of the tip electrode by the blood flow. Furthermore, coronary artery occlusion might be possible if RFA is applied at adjacent to the epicardial coronary artery. Transcatheter cryoablation (Cryo) has been used for supraventricular tachycardia. But, the efficacy of transcatheter Cryo for ventricular tachycardia (VT) is still controversial, because of its limited lesion size. We hypothesized that the efficacy of Cryo on lesion size might increase if the catheter profile and catheter-tip length were increased.
Acute experiments: Open-chest transcatheter Cryo was performed to the left ventricular epicardium (EPI) using 7F, 6mm tip and 9F, 8mm tip in the pig In some Cryo, epicardial coronary arteries or fat were targeted to evaluate the effects of Cryo on epicardial vessels and the influence of fat on the lesion size. Catheter-tip temperature was set to −70 to − 80°C and Cryo duration was set to 240 sec.
Chronic experiments: Closed-chest transcatheter epicardial Cryo were performed in the dog using 7F, 6mm tip and 9F, 8mm tip and the animals were sacrificed at 4 weeks later.
Acute experiments: In 7F, 6mm tip group, EPI lesion volume was 215.8 ± 34.1 mm3 and lesion depth was 4.7 ± 0.4 mm. In 9F, 8mm tip group, EPI lesion volume was 372.6 ± 55.5 mm3 (p<0.05) versus 7F, 6 mm tip) and lesion depth was 5.0 ± 0.7 mm. No evidence of damage in epicardial coronary artery stenosis with internal diameter grater than 0.7 mm was observed. However, lesion depth was significantly smaller when Cryo was applied on the coronary artery and fat.
Chronic experiments: In 7F, 6mm tip group, EPI lesion volume was 200.2 ± 42.7 mm3 and lesion depth was 3.3 ± 0.3 mm. In 9F, 8mm tip group, EPI lesion volume was 296.4 ± 55.5 mm3 (p<0.05 versus 7F, 6 mm tip) and lesion depth was 4.1± 0.9 mm (p<0.05).
Conclusion: Percutaneous transcatheter Cryo to the LV EPI using large and extra-large tip electrode might be useful for transcatheter ablation for VT associated with originating from epicardium or subepicardium without serious complications.