Comparative evaluation of clinically available inferior vena cava filters with an in vitro physiologic simulation of the vena cava.

PURPOSE: A physiologic in vitro model of the human inferior vena cava (IVC) was developed to evaluate the clot-trapping efficiency of various IVC filters. MATERIALS AND METHODS: The flow model closely simulates the physical parameters of the human IVC in fluid viscosity, specific gravity, temperature, and pulsatility; blood flow velocity, volume, and inherent turbulence; and vein orientation, wall compliance, and clot composition. Five filters--Greenfield (G), Bird's Nest (BN), Vena Tech (VT), Simon nitinol (SN), and titanium Greenfield (TG)--were compared by using two vena cava and blood clot sizes and horizontal and vertical orientation of the model. RESULTS: Each filter varied significantly in its clot-capturing efficiency, depending on vena cava size and orientation and emboli size. Overall, decreasing rank order in filter clot-trapping efficiency was SN, BN, VT, TG, and G. CONCLUSION: The in vitro model of the human IVC is an alternative to multicenter clinical trials in evaluating the relative clot-trapping efficiency of various IVC filters.