Abstract 2885: Acute and Chronic Lesion Characteristics of a Novel Hot Balloon Ablation Catheter
RF pulmonary vein (PV) isolation is an effective treatment for AF. Due to the large diameter & variable anatomy of human PVs, the procedure is sometimes challenging with standard catheters. We studied the histopathologic lesion characteristics of a novel hot balloon ablation catheter (Toray-Satake Balloon, Toray Industries Inc).
METHODS: Thirteen swine were used. Pigs were anesthetized & ventilated. A 25mm hot balloon catheter was advanced over a wire into the PV through a 13 Fr transseptal guide. The catheter was inflated with a saline/contrast solution & ablation was performed at balloon temperatures of 60, 70 or 80° C for 300 sec. Eleven animals were sacrificed acutely & 2 were survived 30 days to evaluate chronic lesion characteristics.
RESULTS: Twenty-seven PVs were treated (4 each at 60, 70 & 80° C with a single and 15 with multiple ablations per vein). Electrical isolation was seen in 2/4 at 60°, 3/4 at 70° and 4/4 at 80°C. The 15 veins ablated (up to 4 times) at 70°C until PV isolation was seen achieved block in 14/15 (93%) PV with a mean of 1.4 +/− 0.9 burns. At necropsy, exam revealed extra-ostial lesions without thrombus or charring. In PV treated at 60°C, lesions appeared non-circumferential. Histopathology revealed transmural & non-transmural injury, though the histological severity of acute thermal injury did not predict isolation. In PV ablated at 70° or 80°C transmural lesions were seen (up to 5mm depth) with adherent fibrin but no charring. One PV subjected to 4 attempts at isolation with 70° revealed marked circumferential inflammation & thermal injury despite continued conduction. At 80°C, lesions displayed greater histopathologic uniformity, but more marked fibrin deposition. Chronic lesions revealed granulation tissue and fibrosis. Calcification & giant cell reaction was seen in 1 vein. Minimal adjacent lung fibrosis was seen in 1 animal. No evidence of embolic events were seen and histopathology of the phrenic nerve and esophagus were normal in all specimens.
CONCLUSIONS: The hot balloon ablation catheter is an effective tool for PVI. A dose dependant response is suggested at temps ranging from 60–80° C. Acutely, PV to LA conduction block is observed despite apparent persisting connections by acute histology.