Percutaneous Radiofrequency Ablation to Occlude the Thoracic Duct: Preclinical Studies in Swine for a Potential Alternative to Embolization

Purpose: To investigate the feasibility of percutaneous radiofrequency (RF) ablation to occlude the thoracic duct (TD) in a swine model with imaging and histologic correlation. Materials and Methods: Six swine underwent TD RF ablation. Two terminal (4 hours, 1 open and 1 percutaneous) and 4 survival (30 days, all percutaneous) studies were performed. Two 20-gauge needles were placed adjacent to the TD under direct visualization after right thoracotomy or under fluoroscopic guidance using a percutaneous transabdominal approach after intranodal lymphangiography. RF electrodes were advanced through the needles, and ablation was performed at 90°C for 90 seconds. Lymphangiography was performed, and the TD and adjacent structures were resected and examined microscopically at the end of each study period. Results: Four of 6 subjects survived the planned study period and underwent follow-up lymphangiography. Two subjects in the survival group were euthanized early—1 after developing an acute chylothorax and 1 because of gastric volvulus 14 days after ablation. Occlusion of the targeted TD segment was noted on lymphangiography in 3 of the 4 remaining subjects (2 acute and 1 survival). Histology 4 hours after RF ablation demonstrated necrosis of the TD wall and hemorrhage within the lumen. Histology at 14 and 30 days revealed fibrosis with hemosiderin-laden macrophages replacing the ablated TD. Collagen degeneration within the aortic wall involving a maximum of 60% thickness was noted in 5 of the 6 subjects. Conclusions: Percutaneous RF ablation can achieve short-segment TD occlusion. Further study is needed to improve safety and demonstrate clinical efficacy in treating TD leaks.