FEM Simulation of Subintimal Angioplasty for the Treatment of Chronic Total Occlusions

Sub-intimal angioplasty is a highly challenging technique for percutaneous treatment of chronic total occlusion (CTO) in blood vessels and the development of predictive tools for preliminary evaluation of potential outcomes and risks could be very useful for clinicians. While Finite Element (FE) simulation is a well established approach to investigate partial occlusions, its extension to CTO has not been investigated yet, because of several additional issues that have to be addressed. In this work, we discuss the implementation of a FE model to simulate the main steps of the procedure, i.e. sub-intimal insertion of an initially folded balloon in a false lumen, inflation from eccentric position, deflation and extraction. The model includes key morphological features of the CTO and possibility to vary spatial distribution of material properties to account for different constituents and degree of calcification. Both homogeneous and heterogeneous CTO configurations were analysed, comparing arterial stress state, plaque compression and post-procedural recoil. For a peak inflation pressure of 12 bar, the degree of lumen restoration was in the range 65-80%, depending on plaque heterogeneity. After balloon extraction, homogeneous highly calcified plaques exhibited substantial recovery of original shape. For homogeneous and heterogeneous CTO values of peak von Mises stress in the arterial wall were of the same order of magnitude (range 1-1.1 MPa) but at different locations. Results compared favourably with data reported in literature for post-procedural lumen restoration and arterial stress data, confirming potential usefulness of the approach.