The Biomechanics of Arterial Aneurysms

Abstract

The formation of an arterial aneurysm is believed to be a multifactorial and predominantly degenerative process, resulting from a complex interplay between biological processes in the arterial wall and the hemodynamic stimuli on the vessel's wall. Once an aneurysm forms, the repetitive pressure and shear stresses exerted by the blood flow on the weakened arterial wall generally, but not always, cause a gradual expansion. As the wall geometry, composition, and strength progressively degrade through the enlargement process, the aneurysm ruptures when the wall of the distended artery fails to support the stresses resulting from the internal blood flow. This review surveys recent progress in this area and provides a critical assessment of the contribution made by hemodynamics studies to the current understanding of the pathogenesis of the disease and to its clinical management. Circle of Willis: a roughly circular connection of arteries located at the base of the brain and formed by the anterior communicating artery, the two anterior cerebral arteries, the two internal carotid arteries, the two posterior communicating arteries, and the two posterior cerebral arteries viii Contents

Creating a model of diseased artery damage and failure from healthy porcine aorta

“…Therein, for example, loss of elastin, and the accompanying increase in wall compliance, stimulates cellular mechanotransduction and, in turn, complex remodelling of collagen components [66]. Wall mechanics in atherosclerosis are yet more complex due to the presence of the athersclerotic plaque which, despite efforts to capture its mechanical properties, is exceedingly difficult to incorporate into healthy arteries with many studies opting to induce the process in vivo [67,68].…”

Investigation of material modeling in fluid–structure interaction analysis of an idealized three-layered abdominal aorta: aneurysm initiation and fully developed aneurysms

“…Although the aorta was assumed as a single-layered structure for simplification in most studies, it has three layers: intima, media, and adventitia [54]. Since imaging techniques are not sufficiently reliable to obtain the accurate vessel thickness, vessel thickness was assumed to be uniform, having the same material properties through the vessel.…”

Dynamics of pulsatile flow through model abdominal aortic aneurysms

“…Yet, as observed by Vorp (2007), many smaller lesions rupture (13 % of those of less than 5 cm), while larger lesions may not rupture over long periods (54 % of those of over 7 cm). This leaves physicians to face the dilemma of either subjecting patients to a complex surgery with high morbidity and complications or to an unknown risk of rupture, to paraphrase Lasheras (2007). As pointed out by Humphrey & Taylor (2008) and Humphrey & Holzapfel (2012), there is a pressing need to better understand the mechanobiology, pathophysiology and treatment of abdominal aortic aneurysm; an understanding that should result from combining advances in vascular biology, medical imaging, biofluid mechanics and biosolid mechanics.…”

“…To provide a background and motivation for the present study, we briefly mention some of the recent work on the haemodynamics of abdominal aortic aneurysms; for a more elaborate discussion the reader is referred to the reviews by Lasheras (2007) and Humphrey & Taylor (2008). A highly advanced approach, which has increasingly become the standard, is the experimental and computational study of blood flow in models of the cardiovascular system obtained from patient-specific anatomical data acquired by medical imaging.…”