A novel deployment design of vena cava filters might be the solution to their blockage problem.

The blockage of a vena cava filter (VCF) by the captured blood clots presents a serious problem to the patients. Commercially available cone-shaped VCFs such as the Gunther Tulip filter has an inherent structural flaw that leads the captured blood clots to be trapped in their front spire areas where the flow-induced shear stress is relatively low so that the clots cannot dissolve fast enough and will accumulate, gradually block the central passages of the filters. It is well known that for a Hagen-Poiseuille flow in a circular tube, the flow-induced shear stress is highest at the wall of the tube and lowest along its axis. Herein, we hypothesize that by reversely deploying a cone-shaped filter in the vena cava, the filter's blockage problem might be prevented. First of all, this kind of deployment scenario can force the captured blood clots to stay in the peripheral areas of the vena cava and keep the central passage of the filter unblocked. Secondly, this scenario can expose the captured blood clots to relatively high shear stress that may dissolve the clots faster.
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