Effects of Thrombosed Vena Cava Filters on Blood Flow: Flow Visualization and Numerical Modeling

Abstract

Inferior vena cava (IVC) filters are used to prevent pulmonary embolism (PE) in patients with deep vein thrombosis for whom anticoagulation is contraindicated. IVC filters have been shown to be effective in trapping embolized clots and preventing PE; however, among the commercially available designs, the optimal balance of clot capture efficiency, clot dissolution, and prevention of to vena cava occlusion is unknown. Clot capture efficiency has been quantified in numerous in vitro studies, in which model clots are released into a mock circulation system, with the relative capture efficiency of various IVC filters analyzed statistically. In general, two-stage filters have been found to be more efficient than one-stage filters. However, other factors may play a role in the ultimate dissolution of clots and in the overall effect of the resulting blood flow on caval vasculature. Clot dissolution has been shown to increase with increasing wall shear stress, while low and oscillating wall shear stresses are known to have a deleterious effect on vessel walls, causing intimal hyperplasia. This paper describes the effect of IVC filters on blood flow, velocity patterns, and wall shear stress by flow visualization and computational fluid dynamics.

A Computational Method for Predicting Inferior Vena Cava Filter Performance on a Patient-Specific Basis

“…The IVC filter strut hooks were not included in the IVC filter contact surface (Fig. 2b-*) under the assumption that the strut hooks embed into the vein wall, which agrees with previous studies [9,7,19] and clinical observations. A high friction coefficient (2.0) was used at the interface between the strut ends and the IVC vein wall to simulate the resistance to movement provided by the strut hooks and to obtain a stable placed state.…”

“…Unlike previous computational studies, which considered blood flow in idealized IVC geometries without IVC-IVC filter interactions [17,5,7,19,20], the present study addresses new aspects of IVC filter placement: 1) the in Keefe B. Manning BIO-13-1517…”

“…The altered flow may be thrombogenic, or may promote embolus dissolution. In order to investigate these conditions, a teardrop-shaped geometry similar to the emboli used by other authors [9,10,13,14,17,7] was created with a volume of 0.63 cm 3 (Fig. 1d), which lies in the range of emboli observed clinically in IVC filters [31].…”

Design Optimization of Vena Cava Filters: An Application to Dual Filtration Devices

“…All vessels are taken to be straight and rigid (e.g., [12][13][14][15][16]), and the IVC has an inner diameter of 23mm, per the average cava diameter in [17]. The diameters and entry angles of the common iliac and renal veins into the IVC, as noted in Fig.…”

Numerical and experimental study of the fluid flow through a medical device

“…Usually the main therapies used for the treatment of PTE are anticoagulation and fibrinolysis but sometimes they are contraindicated or ineffective, so it is necessary to use other techniques. Inferior vena cava filters have been shown to be effective in trapping embolized clots and preventing PTE (2). They were designed for the first time in 1967 and since then their design has been improved considerably and their use has increased (3).…”