Intracranial and Abdominal Aortic Aneurysms: Similarities, Differences, and Need for a New Class of Computational Models

Abstract

Intracranial and abdominal aortic aneurysms result from different underlying disease processes and exhibit different rupture potentials, yet they share many histopathological and biomechanical characteristics. Moreover, as in other vascular diseases, hemodynamics and wall mechanics play important roles in the natural history and possible treatment of these two types of lesions. The goals of this review are twofold: first, to contrast the biology and mechanics of intracranial and abdominal aortic aneurysms to emphasize that separate advances in our understanding of each disease can aid in our understanding of the other disease, and second, to suggest that research on the biomechanics of aneurysms must embrace a new paradigm for analysis. That is, past biomechanical studies have provided tremendous insight but have progressed along separate lines, focusing on either the hemodynamics or the wall mechanics. We submit that that there is a pressing need to couple in a new way the separate advances in vascular biology, medical imaging, and computational biofluid and biosolid mechanics to understand better the mechanobiology, pathophysiology, and treatment of these lesions, which continue to be responsible for significant morbidity and mortality. We shall refer to this needed new class of computational tools as Fluid-Solid-Growth (FSG) Models.

Constitutive modelling of arteries

“…The needs he identifies are embraced by the sentence 'Because of the inherent complexities of the microstructure and biomechanical behaviour of biological cells and tissues, there is a need for new theoretical frameworks to guide the design and interpretation of new classes of experiments'. Whilst Humphrey's review covers a wide range of soft tissues, that of Humphrey & Taylor (2008) is more specific in that it compares and contrasts the biology and mechanics of intracranial and abdominal aortic aneurysms. They emphasize the need to couple more effectively the wall biosolid mechanics with the biofluid dynamics of blood flow, vascular biology and medical imaging in order to improve understanding of the mechanobiology and pathophysiology of aneurysms and their treatment.…”

Dynamics of pulsatile flow through model abdominal aortic aneurysms

“…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.…”

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

“…Cerebral artery aneurysms (CAA) and abdominal aortic aneurysms (AAA) are the most common aneurysm types. The AAA arises in the infrarenal aorta with a diameter greater than 3 cm and can be up to 9 cm in length [1,2]. Most of the studies on aneurysms have focused on already existing realistic or idealized aneurysms [33][34][35][36][37][38][39][40][41][42][43] with the aim of defining a relevant rupture criterion [4,7,10,19,20,24].…”

“…Although the reasons of AAA formation are not yet well clarified, suggestions are either local weakening of the artery due to loss of medial elastin and then the degeneration of smooth muscle cells (SMC) or the existence of atherosclerotic plaque with ILT as an initial mechanism [1]. Researchers have considered different constitutive models for investigating inception and growth of aneurysms [45][46][47][48].…”