Short-term survival after radiofrequency Ablation (RFA) of the lung in swine model

Introduction: Radiofrequency ablation utilizes a high frequency alternating current to create coagulation necrosis. Radiofrequency ablation has been extensively studied in many organs, and in the last few years, investigators have been to understand the effects and safety of RF ablation in lung tissue. Porcine and rabbit models have been used in the past to evaluate the immediate effects of RFA in lung tissue. This is the first series of RFA efficacy in a large animal model to evaluate short-term survival and early complications due to RFA. Material and Method: Fifteen domestic female swine were divided into two groups. The experimental group underwent radiofrequency ablation of the right lung with the target temperature above 70 C° for at least 5 minutes. In the control group, same method was used, but no RFA energy was delivered. All animals were assessed for vital signs, activity level, respiratory manifestations, general well-being, chest-tube drainage, and surgical wound healing for thirty days. On day 30, animals were sacrificed and their lungs ware examined for morphological changes. Results: The mean values for power, impedance and temperature were 23.63 ± 8.24 W, 88.15 ± 17.87 Q, and 72.51 ± 8.66°C, respectively. There was no significant difference in vitals signs and general well-being between the two groups. Only the experimental group showed evidence of respiratory distress, which was noticed mainly on the day of procedure. Air leakage and pleural adhesions were major finding in both groups. No evidence of purulent pleural effusion or pneumonia was observed. Gross examination showed a central necrotic area with a surrounding fibrous pseudocapsule and neovascularization. Important histological features of RF lesions were circumscribed congested necrotic parenchyma, granulation tissue, fibrosis, and vascular thrombosis. Conclusion: Radiofrequency ablation of lung tissue can be achieved in a safe manner with negligible morbidity and no mortality. There was no intra-operative mortality, and the post-operative recovery time was fast and uneventful. Although respiratory distress and pleural adhesions were common findings, they were comparable with any intrathoracic procedure. Pathological examination indicates that RFA causes coagulation necrosis, formation of granulation tissue and tendency for absorption in a predictable fashion.Surgery, Department ofMedicine, Faculty ofGraduat