Computational evaluation of inferior vena cava filters through computational fluid dynamics methods

Abstract

A dvanced computing technology increasingly allows the expeditious calculation of solutions to complex problems. Three-dimensional (3D) finite element modeling and computational fluid dynamics, although historically time consuming and expensive, are becoming more accessible and thus more frequently utilized in improving medical devices (1).Finite element analysis (FEA) involves first modeling the system being analyzed with discrete elements, each of which allows for the variable being studied (e.g., stress, temperature, flow) to be approximated within its domain. After modeling is complete, a numerical matrix is assembled, which represents both the properties of the individual elements and the inter-relationships between the surrounding elements. Finally, known constraints on the problem (e.g., internal pressures) are applied as boundary conditions, and numerical techniques are used to solve the system of equations represented by the matrix. This solution leads to an approximation of the variable being studied (Fig. 1). This method is particularly useful for finding solutions in complex geometries for which closed-form solutions may not exist. Computational fluid dynamics (CFD) is a similar numerical technique used to estimate the behavior of fluids in complex geometries. CFD can be used to model blood flow through the vasculature and around intravascular devices to aid in decision making (2). Computational methods are typically less time-consuming and more cost-effective than some of the current alternatives to testing medical devices in vitro.Today, 3D simulation is used for designing, positioning, and testing devices (3). One such device is the inferior vena cava (IVC) filter, used to trap emboli from the lower extremities when medical anticoagulation is contraindicated. Complications of IVC filter placement include cava wall perforation, intimal hyperplasia, thrombosis, strut fracture, and embolization. Understanding the dynamic environment that IVC filters are placed in, in a patient-specific manner, could potentially decrease the occurrences of these complications (Fig. 2). Evaluating credibility of CFD in medical device designComplex CFD methods have the potential to change how we practice patient centered medicine; however, they must first be shown to accurately reflect the scenarios that they model. The reliability of these methods must be verified before they can be used to affect biomedical design and clinical practice. The American Society of Mechanical Engineers (ASME) recently released the V&V 40, a set of standards that outlines a framework to assess ABSTRACT Numerical simulation is growing in its importance toward the design, testing and evaluation of medical devices. Computational fluid dynamics and finite element analysis allow improved calculation of stress, heat transfer, and flow to better understand the medical device environment. Current research focuses not only on improving medical devices, but also on improving the computational tools themselves. As methods and computer technology allow ...

Numerical simulation and in vitro experimental study of the hemodynamic performance of vena cava filters with helical forms

“…A series of IVCFs were proposed, and the performance of these IVCFs was evaluated through numerical simulations and in vitro microthrombus capture experiments. Through CFD numerical simulation [25], hemodynamic characteristics involving helicity, wall shear stress, blood helicity induced by IVCF, radial stress of IVCF on the blood vessel wall during blood ow, axial impact stress of blood on IVCF, and blood vessel strain were evaluated. In addition, in vitro experiments were carried out to evaluate the capture e ciency of IVCFs with different con gurations.…”