Computational Modeling of Blood Flow in the TrapEase Inferior Vena Cava Filter

Schematic of the three-dimensional flow configuration with nomenclature and orientation.

Wall shear stress and velocity contours on two orthogonal, longitudinal planes (rotated 90 degrees about the filter axis) that slice the geometric center of the filter and vein. All computed stresses and velocities were normalized by the corresponding value for fully developed flow in a long, straight pipe (ie, Poiseuille flow). Flow is left to right. For the wall shear stress, the x-axis denotes the distance (in millimeters) from the downstream tip of the filter, and the plot is aligned and graphically scaled to match the velocity contour plots. Excellent flow symmetry is observed, which was expected because the filter was placed in the center of the IVC model and the filter was free of tilt.

Normalized wall shear stresses and velocity contours for a filter partially occluded by a 0.5-mL spherical thrombus in the (a) downstream and (b) upstream trapping positions. Stagnant and recirculating flow is observed downstream of both thrombi. For the thrombus trapped upstream (b), the shear stresses on the walls ipsilateral to each thrombus were lower than the corresponding stresses on the opposite wall, except in close proximity to the thrombus.

Flow pattern and normalized wall shear stress for a one-mL spherical thrombus in the downstream trapping position. The peak velocity occurs in the narrow passage between the cava wall and the thrombus, and the peak wall shear stress occurs near the thrombus.

Graph shows the normalized wall shear stresses for different sizes of thrombi. The peak wall shear stress occurs slightly downstream of each thrombus and increases with thrombus volume.

Normalized wall shear stresses and velocity contours for flow past (a) spherical, (b) cone-shaped, and (c) ellipsoidal thrombi. The normalized velocity color scale on the left applies to the ellipsoidal flow pattern (c); the color scale on the right applies to the spherical (a) and conical (b) flow patterns. Each thrombus was 1.875 mL. The ellipsoidal thrombus had a peak wall shear stress approximately three mm farther downstream due to the downstream jump in velocity gradient near the point where the thrombus and filter meet.