A Technique for Comparing Wall Pressure Distributions in Steady Flow Through Rigid Versus Flexible Patient-based Abdominal Aortic Aneurysm Phantoms
Abdominal aortic aneurysms (AAAs) represent permanent, localized dilations of the abdominal aorta. Here, we describe a procedure for noninvasively measuring the flow-induced wall pressure distribution in both effectively rigid, thick-wall and flexible, thin-wall phantoms under perfusion conditions dynamically simulating the in vivo abdominal aorta. Both phantoms accurately replicated the shape of patient AAAs including the renal and iliac arteries, and the flexible phantoms reflected patient tissue mechanical properties as well. As an example of their use, wall pressure distributions measured in rigid and flexible phantoms derived from one representative patient under flow conditions emulating the aorta at rest are presented. In both phantoms, there was a net pressure decrease from the upstream end of the bulge to the downstream end. However, there was a five times larger variation of wall pressure magnitude along the bulge region of the flexible phantom than along the rigid phantom, 6–7 mmHg versus more than 30 mmHg. In addition, in the rigid phantom, pressure signal fluctuations were of the same order of magnitude as the pressure transducer inherent noise level. In the flexible phantom, they were approximately 10 times the noise level in the absence of flow, suggesting that flow in the flexible phantom was unstable even at Reynolds number 500.
KeywordsAortic Aneurysm Model Phantom Flow Wall Pressure
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