Biological, Geometric and Biomechanical Factors Influencing Abdominal Aortic Aneurysm Rupture Risk: A Comprehensive Review

Abstract

The current clinical management of abdominal aortic aneurysm (AAA) disease is based to a great extent on measuring the aneurysm maximum diameter to decide when timely intervention is required. Decades of clinical evidence show that aneurysm diameter is positively associated with the probability of rupture, but that other parameters may also play a role in causing or predisposing the AAA to rupture. Biological factors associated with smooth muscle apoptosis are implicated in AAA expansion while geometric and biomechanical factors identified by means of computational modeling techniques have been positively correlated with rupture risk with a higher accuracy and sensitivity than maximum diameter alone. The objective of this review is to examine the factors found to influence AAA disease progression, clinical management and rupture, as well as a patent review that highlights developments in this arena in the past few years.

Pentagalloyl Glucose and Its Functional Role in Vascular Health: Biomechanics and Drug-Delivery Characteristics

“…The aorta would become less compliant concomitantly with time to accommodate the body’s hemodynamic requirements. 24,139 Inflammatory responses in conjunction with MMP infiltration results in the abnormal dilation of the infrarenal portion of this large blood vessel. 52,53,139 As aneurysm geometry measures and wall thickness are known determinants of AAA pathology, 28,105,125,139,153 PGG has the potential to both stabilize the vessel and prevent local biomechanical stress build up (see Figs.…”

“…Nevertheless, this favorable biomechanical characteristic resulting from PGG treatment could be critical for treatment of AAA patients and potentially prevent AAA rupture, since the primary cause of rupture is elevated wall stress and decreased wall strength. 139 …”

“…These aneurysms may have an intraluminal thrombus (ILT), which further complicates the arterial wall biology, vessel luminal morphology, blood flow dynamics, and its associated tissue mechanics. 139 AAA pathology is believed to be a result of medial lamellar degradation, due to a combined effect of vascular smooth muscle cell (VSMC) apoptosis, heightened inflammatory responses, increased oxidative stress, and disruption of tissue enzymatic homeostasis. 57,109,139 Increased secretion of serine proteinases and MMP in AAA have resulted in a reduction in elastin content and elastin crosslinking, and an increase in collagen crosslinking.…”

“…139 AAA pathology is believed to be a result of medial lamellar degradation, due to a combined effect of vascular smooth muscle cell (VSMC) apoptosis, heightened inflammatory responses, increased oxidative stress, and disruption of tissue enzymatic homeostasis. 57,109,139 Increased secretion of serine proteinases and MMP in AAA have resulted in a reduction in elastin content and elastin crosslinking, and an increase in collagen crosslinking. 24 Reduced elastin is associated with increasing AAA diameter, and the increased collagen content is correlated with high local wall stresses.…”

“…99 This altered ECM is unable to withstand the resulting high wall stress and altered blood flow patterns. 139 The abnormally dilated abdominal aorta often ruptures if left untreated and this event is associated with a high mortality rate. 128 Therapeutic options for AAA patients are limited and no single drug or pharmacological therapy has been proven effective for preventing growth or rupture of AAA.…”