Sequential Balloon Modeling for Robust Percutaneous Transluminal Angioplasty Simulation.

Percutaneous transluminal angioplasty (PTA) is the standard treatment for atherosclerotic stenoses. It involves inflating a balloon inside the stenosis to create large deformations and achieve permanent enlargement of the lumen. PTA is typically performed prior to the placement of a stent as a preliminary reshaping procedure. Reshaping angioplasty as a standalone treatment emerged since the introduction of drug-coated balloons. PTA numerical simulation can help predict procedure outcomes, but faces challenges in cases of severe stenosis, notably due to balloon modeling strategy: exhaustive folded balloon models are computationally costly, while simplified balloon surface models experience excessive membrane strains which compromise simulation robustness. This work introduces a new strategy based on sequential balloon modeling (SBM). SBM aims to ensure the robustness of PTA finite element simulation, in cases of high inflation range, for example, PTA on severe stenosis. Such condition results in a high gain from the initial to the maximal balloon diameter, causing simulation divergence due to excessive element deformation, combined with contact. SBM limits the deformation experienced by the balloon by dividing the whole inflation in several steps, each with a limited amount of diametral gain for the balloon. The angioplasty balloon is replaced by several balloons, modeled as unfolded, which come into play sequentially. These artificial balloons aim to dilate the stenosed artery progressively and to reproduce the pressure-diameter curve of the modeled balloon as described by the manufacturer datasheet. In this work, SBM is combined with parametric stenosis modeling to build a robust and versatile model for estimating the permanent set after reshaping. To demonstrate the robustness of this strategy, we first investigate parametric single-stenosis models to assess the influence of geometric parameters and plaque type on post-PTA results. We focus on severe degrees of stenosis and large artery calibers, which are rarely studied in the literature. We then illustrate how this strategy can be used to replicate a complex, patient-specific iliac artery stenosis case by combining single-stenosis models. The SBM strategy demonstrates promising results in terms of versatility and robustness, paving the way for further PTA simulation validation and mechanical insights to optimize treatment strategies for severe stenosis.