Inferior vena cava filters: in vitro comparison of clot trapping and flow dynamics

Using a flow model that simulated the inferior vena cava (IVC), the authors conducted an in vitro comparison of the Mobin-Uddin (MU), Kimray-Greenfield (KG), Amplatz spider (A), Günther basket (G), Simon nitinol (SN), and bird's nest (BN) filters. The following parameters were evaluated: clot-trapping capacity and flow dynamics, which included measurements of pressure gradients across filters and assessment of flow patterns. The MU, A, G, SN, and BN filters trapped an average of 80%-100% of small clots and 100% of large clots. The KG filter, in a central position, trapped 0%-10% of small clots and 60%-100% of larger clots. In the eccentric position, the KG filter trapped only 20% of all clots. The BN and SN filters showed the least flow turbulence. Moderate turbulence was observed with the G and KG filters, while the MU and A filters showed marked turbulence. The current standard KG filter allowed the passage of small and large clots. When specific parameters were considered--such as clot-trapping capacity and flow-dynamic performance--the BN, SN, and G IVC filters were superior to the other filters that were tested.