Intraoperative damage monitoring of endoclamp balloon expansion using real-time finite element modeling

Abstract

Endovascular clamping can be achieved by means of intraluminal occlusion with an Endoclamp balloon. Circumventing the need for opening the thoracic cage provides significant benefits in terms of reducing trauma for the patient. This procedure, however, induces risks of damage to the aortic lumen by way of over-expansion of the balloon, exposing the aortic tissue to unsafe levels of loading. Accurate estimates of the induced stress and consequent damage are required intraoperatively to warn the surgeon and mitigate the risk of injury.This paper proposes a method for intraoperative monitoring of the inflicted damage to the arterial tissue, by means of finite element modeling. The Total Lagrangian Explicit Dynamic (TLED) finite element (FE) formulation, capable of handling geometric and material nonlinearities, is used. A 2D plane strain formulation is used to additionally simplify and speed up the execution time by reducing the number of degrees of freedom involved, meanwhile retaining sufficient accuracy for the proposed application. A material model incorporating damage as an internal variable allowed tracking of the degree of injury to the artery. The large amount of computation needed to solve for the stress field is relieved by using dedicated massively parallel hardware. An Nvidia CUDA GPGPU (General Purpose Graphics Processing Unit) is employed to parallelize critical portions of the TLED algorithm. The accuracy of the solution is verified against an industry-proven FE package Abaqus. Results show significant speed-ups compared to Abaqus, thereby retaining a sufficient degree of accuracy.