Feasibility and Acute Safety Study of Radiofrequency Energy Delivery to the Vena Caval Wall Via an Inferior Vena Cava Filter in Swine

Abstract

Retrievable inferior vena cava (IVC) filters are self-expanding metallic devices implanted in the IVC to prevent migration of thrombi from the deep veins of the legs and pelvis to the lungs. The risk of complications from the filters increases with duration of implantation, but retrieval may be difficult due to intimal hyperplasia around the components of the filter. In this study, the potential for delivery of radiofrequency (RF) energy to the IVC wall via the filter was investigated. IVC filters were deployed in four swine while attached to a snare connected to a 480 kHz RF generator. Energy ranging from 0 to 48 kJ was applied via the filter followed by resheathing and withdrawal of the filter while connected to a force measurement device. Resheathing forces for the zero-energy cohort and pooled data from the 6–24 kJ cohorts were 4.50 ± 0.70 N and 4.50 ± 0.75 N, respectively. Petechial hemorrhages and variable nonocclusive thrombi were noted in some cohorts including the zero-energy cohort, consistent with delivery and acute retrieval of an IVC filter. Histologically, the extent of RF-induced injury was subtle at 6 kJ with focal areas of homogenized collagen while the 12 kJ cohort showed segmental tissue charring with coagulation necrosis, which was more extensive for the 24 kJ cohort. The 48 kJ energy caused more extensive and nontarget organ damage. The study demonstrated feasibility of delivery of RF to the IVC wall via a deployed filter, supporting further study of the ability of local RF heating of the IVC wall to inhibit the neointimal hyperplasia or as an aid in retrieval.