Comparison of endocardial and epicardial lesion size following large-tip and extra-large-tip transcatheter cryoablation.

BACKGROUND The efficacy of transcatheter cryoablation for ventricular tachycardia (VT) remains controversial because of the limited size of the lesion produced. An increased lesion size if the cryoablation catheter profile and catheter tip length were increased was hypothesized. METHODS AND RESULTS Closed-chest transcatheter cryoablation was applied with 7F, 6-mm tip (n=11, 7F group) and 9F, 8-mm tip (n=8, 9F group) catheters to the left ventricular (LV) endocardium and epicardium. Catheter-tip temperature was set to -70 to -80 degrees C, and cryoablation duration was set to 240 s. In acute experiments in the 7F group, endocardial lesion volume was 144.1 +/-86.0 mm(3) and lesion depth was 5.1 +/-1.6 mm, and epicardial lesion volume was 205.6 +/-157.8 mm(3) and lesion depth was 4.7 +/-2.2 mm. In the 9F group, endocardial lesion volume was 301.5 +/-177.4 mm(3) (P<0.001 vs 7F group) and lesion depth was 8.4 +/-1.9 mm (P<0.001 vs 7F group), and epicardial lesion volume was 375.3 +/-167.6 mm(3) (P<0.01 vs 7F group) and lesion depth was 5.0 +/-2.3 mm. CONCLUSIONS Transcatheter cryoablation of the LV endocardium and epicardium using a larger profile and longer tip electrode may be useful for treating VT originating from the midmyocardium or epicardium.