Adjustable temporary venous spring filter: in vitro assessment.

Abstract

The authors performed an in vitro study to evaluate a temporary venous spring filter that can extend vessels of a wide range of diameters to a slit-shaped canal. Filters were placed in thin polyethylene tubes or in porcine inferior vena cava specimens (diameter, 10.0-16.0 mm). Physiologic saline was substituted for blood flow, and blood clots of three sizes (6 x 10, 6 x 20, and 9 x 20 mm) were funneled to the filter. Clot-trapping ability was assessed by the degree of luminal extension. When the luminal extension was increased from 2.6r to 2.8r (where r is the original radius of the vein models), clot-trapping ability increased significantly (61.1%-87.5% in polyethylene tubes and 15.8%-77.5% in venous specimens, P < .001). When the luminal extension was increased to 3.0r, more than 90% of the clots were trapped in all tubes. After trapping the small, medium, and large clots, mean intraluminal pressure elevation was 1.0, 1.0, and 17.0 cm of saline, respectively. Despite its simple design, the spring filter proved to be an efficient filtering device.