Physiological FSI Study for Phonoangiography-Based Rupture Risk Prediction in Abdominal Aortic Aneurysms

This paper presents an in-house code-based physiological fluid–structure interaction (FSI) study for pulsatile blood flow in abdominal aortic aneurysms (AAA) with varying height and width. An in-house FSI solver developed using arbitrary Lagrangian–Eulerian (ALE) framework with finite-volume discretization is employed to perform axisymmetric blood flow simulations in artery with fusiform aneurysm. Considering a pulsatile inlet flow at Womersley number Wo = 16.5, a parametric study is presented with various height (H) to diameter (D) ratio H/D = 0.3, 0.5, 0.7, 1.0 and 1.2 and width (W) to diameter (D) ratio W/D = 0.5 and 1. For identification of severity of aneurysm, the present work attempts to analyze the variation of rupture risk (required for planning treatment strategy) and qualitative hemo-acoustic indicator. After analyzing the two parameters, a correlation which can be harnessed to predict rupture risk based on actual acoustic signals is presented. Integrated pressure force rate (IPFR), which correlates directly with acoustic fluctuation sensed by a digital stethoscope is calculated on the artery surface. Also, rupture potential index (RPI) is calculated based on the ratio of wall stress and ultimate tensile strength of the artery. It is observed that geometries with H/D ≥ 0.7 lead to RPI ≥ 0.3 which is considered critical. Based on the data of RPI and IPFR spectrum, a nonlinear relation is proposed to calculate rupture risk through frequency data. The current work establishes the efficacy of phonoangiography-based diagnosis to assist medical practitioners in planning treatment strategy.