Hemodynamic Analysis of VenaTech Convertible Vena Cava Filter Using Computational Fluid Dynamics.

Jingying Wang,Yue Zhou,Chunhian Lee,Wen Huang,Dong Ke,Fangzhou Han

doi:10.3389/fbioe.2020.556110

Abstract

The VenaTech convertible filter (VTCF) has been widely used as an inferior vena cava (IVC) filter to prevent fatal pulmonary embolism in patients. However, its hemodynamics that greatly affect the filter efficacy and IVC patency are still unclear. This paper uses computational fluid dynamics with the Carreau model to simulate the non-Newtonian blood flows around the VTCF respectively deployed in the normal, reverse and three converted states in an IVC model. The results show that the prothrombotic stagnation zones are observed downstream from the normal, reverse and small open VTCFs, with the streamwise length is nearly eight times the IVC diameter. The no-slip boundary conditions of the thin-wire VTCF arms lead to the “viscous block” effect. The viscous block accelerates the blood flow by 5–15% inside the IVC and enhances the filter wall shear stress up to nearly 20 times that of the IVC only, which contributes to clot capture and thrombus lysis. The relative flow resistance is defined to evaluate the filter-induced resistance on the IVC blood flow that can be regarded as an index of IVC patency with the filter deployment. The flow resistance of the normal VTCF deployment increases dramatically by more than 60% compared with that of the IVC only and is a little higher (6%) than that of the reverse case. As the VTCF converts to a fully open configuration, the flow resistance gradually decreases to that of no filter. This work shows that even very thin VTCF arms can result in the viscous block effect and may cause significant hemodynamic impacts on clot capture, potential thrombosis and flow impedance inside the IVC. The present study also shows that CFD is a valuable and feasible in silico tool for analyzing the IVC filter hemodynamics to complement in vivo clinical and in vitro experimental studies.

Highlights

Pulmonary embolism (PE) from deep vein thrombosis (DVT) has become a disease with considerable rates of morbidity and mortality worldwide (Hirsh and Hoak, 1996; Kaufman et al, 2009; Beckman et al, 2010; Zhang et al, 2015; Kearon et al, 2016; Mozaffarian et al, 2016)
The objective of this study is to evaluate the hemodynamics of the VenaTech convertible filter (VTCF) deployed in the normal and reverse unconverted states, as well as three converted states with different degrees of opening by using computational fluid dynamics (CFD) models that simulate the blood flow around the filter and show the distribution of the filter wall shear stress (WSS)
The blood flows for the normal unconverted, reverse unconverted and three converted states of the VTCF deployed in the inferior vena cava (IVC) are simulated using CFD models for comparison to investigate the hemodynamics of the VTCF including the flow velocity profiles, the filter WSS distributions, and the flow resistances, which have not been discussed in previous experimental or computational studies

Summary

Introduction

Pulmonary embolism (PE) from deep vein thrombosis (DVT) has become a disease with considerable rates of morbidity and mortality worldwide (Hirsh and Hoak, 1996; Kaufman et al, 2009; Beckman et al, 2010; Zhang et al, 2015; Kearon et al, 2016; Mozaffarian et al, 2016). To prevent PE in patients for whom anticoagulation therapy is ineffective or contraindicated, VenaTech Convertible Filter Hemodynamics the inferior vena cava (IVC) filter provides a crucial alternative (Chen Y. et al, 2017; Duffett and Carrier, 2017; Lenchus et al, 2017) that has been in use for more than 40 years and currently appears to be increasing in use (Greenfield et al, 1994; Galanaud et al, 2013; Montgomery and Kaufman, 2016). The subsequent PREPIC2 trial showed that compared with anticoagulant therapy alone, the placement of an IVC filter following short-term anticoagulation did not have any statistically significant benefit in terms of PE recurrence or mortality in patients with acute symptomatic PE (Mismetti et al, 2015). Efforts still need to be made regarding the assessment and optimization of IVC filters (Magnowski et al, 2017)

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