Abstract 12166: Biomechanical Impact of Valve Sparing Procedure Onto the Native Aorta, a Multi-Patient in silico Study

Abstract

Introduction: Ascending thoracic aortic aneurysms (TAA) provide a nidus for dissection, which can be prevented by surgical prosthetic graft replacement. Grafts eliminate risk in resected regions, but are stiffer than native aortic tissue and can thus alter downstream hemodynamics. This study used computational modeling of fluid structure interaction (FSI) to study biomechanical impact of proximal aortic graft replacement on the descending aorta. Methods: TAA pts undergoing cardiac MRI (CMR) prior to and after valve sparing proximal aortic graft replacement (VSR) surgery were studied via FSI. Patient-specific anatomy was reconstructed by segmentation of 3D MR angiography. 4D flow was used to prescribe velocity at the inlet of the model and to define three-elements Windkessel parameters used to impose outlet boundary conditions. Results: FSI models were constructed in 5 male patients (61±10.6 years old) who underwent CMR pre (1.7±1.5 weeks) and post (28.5±2.3 weeks) proximal aortic graft replacement. Qualitative and quantitative comparison of numerical results with 4D-flow data confirmed FSI model’s ability to reproduce patients’ fluid-dynamics (mean RRMSE 0.244±0.059). Regarding post-operative hemodynamics, a post-operative oscillatory shear index (OSI) increment (Pt1: p-value < 0.05) and systolic peak wall shear stress (WSS) variation (Pt1: p-value <0.001, Pt3: <0.01, Pt5: <0.0001) were observed, particularly in proximal descending aorta ( Fig 1 ). Furthermore, from 9 to 63% post-operative distensibility increment was detected. Finally, a mean 4% principal strain intensification was noticed at graft’s suture site if compared to the native portion of the ascending aorta ( Fig 1 ). Conclusion: Computational FSI modeling analysis demonstrates VSR technique to alter downstream biomechanics, including wall shear stress variation and increased strain immediately distal to grafted territories.