Mathematical modeling of the fibrosis process in the implantation of inferior vena cava filters.

An inferior vena cava filter is a medical device that is implanted in the inferior vena cava and is in charge of capturing blood clots before they reach the lungs, preventing from pulmonary embolism. There are some clinical problems regarding the use of inferior vena cava filters. One of them is the difficulty when retrieving the device due to the remodeling of the vena cava. Huge effort has been made in creating computational models that reproduce tissue remodeling, but no attention has been paid to the fibrosis phenomenon occurring in the inferior vena cava. In this work, a continuum computational model that reproduces the fibrosis in the presence of an antithrombotic filter is presented. Diffusion-reaction equations are used for modeling the mass balance between species in the venous wall. The main species considered to play a key role in the process of fibrosis are smooth muscle cells, endothelial cells, matrix metalloproteinases, vascular growth factors and the extracellular matrix. The developed model has been implemented on an idealized axisymmetric geometric vena cava model. Moreover, a sensitivity analysis has been performed to study the parameters influence on the evolution of the model. Results show that the computational model is able to predict the behavior of the species considered and it captures the key characteristics of lesion growth and the healing process within a vein subjected to non-physiological mechanical forces. Our results suggests that the vessel wall response is mainly caused by the endothelium denudation area and the collagen turnover among other factors.