Efficacy of pulmonary vein isolation with a novel hot balloon ablation catheter

Due to the variable anatomy of the human pulmonary vein (PV), PV isolation for atrial fibrillation ablation is challenging. A novel hot balloon ablation catheter has been developed to improve ablation outcomes. The efficacy, histopathologic lesion characteristics, and thermodynamics of this technology were examined.

Swine underwent left atrial (n = 24) and superior vena cava (SVC, n = 7) catheterization with a compliant balloon catheter filled with saline and contrast. After PV mapping and angiography, ablation was performed with radiofrequency energy heating of the balloon contents. Central balloon temperatures were varied from 60°C to 90°C, and durations of energy delivery were varied from 60 to 300 s. Endocardial and epicardial temperatures were recorded contiguous to the balloon during SVC ablations. Pathology was examined.

With a mean of 1.4 ± 0.9 ablations per PV at 70°C, 93% were electrically isolated. Necropsy exam revealed extraostial lesions without charring. PVs ablated at temperatures ≥80°C and durations ≥180 s were associated with a high rate of successful isolation with a single ablation. Higher-temperature lesions displayed greater histopathologic uniformity, but more marked fibrin deposition. Chronic lesions revealed granulation tissue and fibrosis. No thromboembolic events were observed and histopathology of the phrenic nerve and esophagus was normal in all specimens.

The hot balloon ablation catheter appears to be a safe and effective tool for PV isolation. Higher temperatures and longer ablation durations are associated with a higher single ablation success rate.