Physiological Flow Evaluation in Healthy and Graft-Treated Thoracic Aortas Using Optical Techniques

Cardiovascular disease presents in the thoracic aorta, as aneurysms or dissections due to altered haemodynamics. Surgical repair typically involves replacing diseased segments with vascular grafts, which can alter native flow environments. This study investigates the influence of geometry on pulsatile flow dynamics using rigid phantoms, to identify flow features relevant to graft performance.

Phantom geometries were derived from anatomical references and literature-based dimensions representative of healthy and graft-treated thoracic aortas. The phantoms were cast from Sylgard 184, and experiments used a Newtonian blood analogue with a matched refractive index (n = 1.414). Pulsatile conditions replicated the physiological aortic waveform, and flow behaviour was captured using stereoscopic particle image velocimetry.

Results show that geometric features such as tapering in the aortic arch, differences in branch diameter and branching angles affect flow division, recirculation zones, and local shear regions. Aortic arch curvature influences the shape of secondary flow structures and downstream flow recovery. These findings provide novel insight into blood flow patterns, where deviations from native flow may impact re-endothelialisation - a key factor in long-term graft performance.

This work enhances understanding of pulsatile flow in large vessels, informs aortic vascular graft design and supports computational fluid dynamics validation for medical device regulatory approval.