Performance Evaluation of Inferior Vena Cava Filters

Performance Evaluation of Inferior Vena Cava Filters

Pulmonary embolism (PE) is a major cause of death and morbidity in the world. Conventional treatments for embolisms include anti-coagulant drugs (Warfarin® or Heparin®), clot anti-thrombotic therapy (streptokinase®), bypass surgery, and thrombo-aspiration. In cases where the patient shows contraindication, failure or complication to anticoagulation drugs, the patient usually receives an inferior vena cava filter (IVCF). Despite its increase in popularity, complete and exhaustive blood flow analysis need to be performed for scenarios that can lead to IVCFs failure. Such scenarios include basket over- filling and filter tilting, among others. This study was conducted to analyze the average blood flow velocity, pressure, and wall shear stresses of the IVCFs at different occlusion levels and determine best and worst case scenarios. All simulations were performed using ANSYS CFX. The inlet’s normalvelocity was set to 5 cm/s. For the outlet, zero relative pressure was prescribed. The walls of the vessel were constrained to no-slip conditions. A viscosity of 3.5 centipoise and density of 1125 kg/m3 were utilized for the blood’s properties. All solutions were set to converge at 10-4 error margin for the momentum and continuity equations. The results showed higher flow velocity, a higher force magnitude as a result of increased occlusion on the filter and vessel walls. Similar findings were observed in the case of wall shear and pressure. In the case of the second degree filter, the peak velocity occurred where there is less distance from parts of the filter to the wall. This can lead to rupture of the vessel, along with the potential dislodging or fracturing of the filter causing sharp debris to apply further damage to the body and potentially resulting in fatality. These studies will help design IVCFs with superior performance.