Differences in radial expansion force among inferior vena cava filter models support documented perforation rates

Objective: Inferior vena cava (IVC) filters are used in patients at risk for pulmonary embolism who cannot be anticoagulated. Unfortunately, these filters are not without risk, and complications include perforation, migration, and filter fracture. The most prevalent complication is filter perforation of the IVC, with incidence varying among filter models. To our knowledge, the mechanical properties of IVC filters have not been evaluated and are not readily available through the manufacturer. This study sought to determine whether differences in mechanical properties are similar to differences in documented perforation rates. Methods: The radial expansion forces of Greenfield (Boston Scientific, Marlborough, Mass), Cook Celect (Cook Medical, Bloomington, Ind), and Cook Platinum filters were analyzed with three replicates per group. The intrinsic force exerted by the filter on the measuring device was collected in real time during controlled expansion. Replicates were averaged and significance was determined by calculating analysis of covariance using SAS software (SAS Institute, Cary, NC). Results: Each filter model generated a significantly different radial expansion force (P <.001), and force was distributed at significantly different rates (P <.001) during expansion. The largest radial expansion force at minimal caval diameter was seen in the Cook Platinum filter, followed by the Cook Celect and Greenfield filters. Radial force dispersion during expansion was greatest in the Cook Celect, followed by the Cook Platinum and Greenfield filters. Conclusions: Differences in radial expansion forces among IVC filter models are consistent with documented perforation rates. Cook Celect IVC filters have a higher incidence of perforation compared with Greenfield filters when they are left in place for >90 days. Evaluation of Cook Celect filters yielded a significantly higher radial expansion force at minimum caval diameter, with greater force dispersion during expansion. Clinical Relevance: This study is the first of its kind to examine the radial expansion force of commercially available IVC filters. Our data demonstrate the importance of evaluating the mechanical properties of filters as a means of interpreting complication rates. Because of the statistically significant differences of radial expansion forces among IVC filter models, we suggest that physicians carefully consider the necessity of IVC filter placement in the first place in light of potential serious complications as well as encourage close follow-up before and after placement of a filter.