Cavitation instability as a trigger of aneurysm rupture

Abstract

Aneurysm formation and growth is accompanied by microstructural alterations in the arterial wall. Particularly, the loss of elastin may lead to tissue disintegration and appearance of voids or cavities at the micron scale. Unstable growth and coalescence of voids may be a predecessor and trigger for the onset of macroscopic cracks. In the present work, we analyze the instability of membrane (2D) and bulk (3D) voids under hydrostatic tension by using two experimentally calibrated constitutive models of abdominal aortic aneurysm enhanced with energy limiters. The limiters provide the saturation value for the strain energy, which indicates the maximum energy that can be stored and dissipated by an infinitesimal material volume. We find that the unstable growth of voids can start when the critical stress is considerably less than the aneurysm strength. Moreover, this critical stress may even approach the arterial wall stress in the physiological range. This finding suggests that cavitation instability can be a rational indicator of the aneurysm rupture.

Computational predictions of damage propagation preceding dissection of ascending thoracic aortic aneurysms

“…Damage models can be categorized in 3 groups: (1) deterministic models in which a pseudoelastic strain energy function (SEF) with a few parameters or damage variables of continuum damage mechanics (CDM) is used to characterize the softening/damage effect, either isotropically 19,23 or anisotropically 24-26 ; (2) probabilistic models in which probabilistic damage process and/or fiber recruitment can be included 27,28 ; and (3) microstructural-based damage models of collagen fibers in which the microscopic damage behavior of individual collagen fibrils is considered and homogenized macroscopically. 29 All these formulations can be categorized as nonlocal 4 or local [15][16][17][18][19][20] damage models.…”

Thrombus rupture via cavitation

“…2 in which g is the remote hydrostatic tension and A and a are the cavity radii before and after deformation respectively. For the sake of brevity we completely omit the details of analysis that can be found in Volokh (2011) or Volokh (2015.…”

“…For example, it might happen that the ruptured thrombus does not shield stresses anymore which raise in the aneurysmal arterial wall. This stress rise might reach the aneurysmal strength directly or it might trigger a similar cavitation instability mechanism in the aneurysmal wall - Volokh (2015).…”

“…The latter gap is filled in the present note. For the detailed methods of analysis the reader is referred to Volokh (2015) to which the present work is complementary.…”

On the near-critical behavior of cavitation in elastic plane membranes

“…More closely related to the current study is the growing interest in cavitation in soft and biological materials. For example, David and Humphrey [34] studied the stress and strain concentration due to the introduction of a circular hole in an anisotropic bio-tissue, Merodio and Saccomandi [35] studied the effect of fibre-reinforcement in the radial direction, McMahon et al [36] and Pence and Tsai [37][38] investigated cavitation due to growth and swelling, respectively, and Volokh [39] suggested that cavitation instability could be a rational indicator of aneurysm rupture.…”