Computational Evaluation of Aortic Aneurysm Rupture Risk: What Have We Learned So Far?

Abstract

In current clinical practice, aneurysm diameter is one of the primary criteria used to decide when to treat a patient with an abdominal aortic aneurysm (AAA). It has been shown that simple association of aneurysm diameter with the probability of rupture is not sufficient, and other parameters may also play a role in causing or predisposing to AAA rupture. Peak wall stress (PWS), intraluminal thrombus (ILT), and AAA wall mechanics are the factors most implicated with rupture risk and have been studied by computational risk evaluation techniques. The objective of this review is to examine these factors that have been found to influence AAA rupture. The prediction rate of rupture among computational models depends on the level of model complexity and the predictive value of the biomechanical parameters used to assess risk, such as PWS, distribution of ILT, wall strength, and the site of rupture. There is a need for simpler geometric analogues, including geometric parameters (e.g., lumen tortuosity and neck length and angulation) that correlate well with PWS, conjugated with clinical risk factors for constructing rupture risk predictive models. Such models should be supported by novel imaging techniques to provide the required patient-specific data and validated through large, prospective clinical trials.

Biomechanical prediction of abdominal aortic aneurysm rupture risk: Sensitivity analysis

“…All of the considerations discussed above suggest that the prediction of potential rupture of AAAs based on the single factor of maximum diameter will be biased and the Law of Laplace has limitations in predicting the rupture of AAAs. Because the Law of Laplace usually assumes the wall stress is proportional to the diameter [11]; however, it may not be valid for complex geometrical features of the AAA walls [11,23]. The obtained regression function demonstrates the multivariate effects on peak wall stress, which is consistent with other previous observations [2].…”

Biomechanical Approach to Improve the Abdominal Aortic Aneurysm (AAA) Rupture Risk Prediction

“…Wang et al [50] showed that computational integration of ILT in 3D models could actually modify not only the value but also the distribution of PWS, thus playing a protective role against rupture but this conclusion was not supported in [62]. On the other hand, there is still some concern regarding the protective role of ILT, since many authors who evaluate the influence of ILT on hemodynamic stress transmission, reported that he presence of ILT fails to reduce the transmission of this stress on the AAA wall, consequently, leaving the AAA rupture risk equalled [63]. AAAs can experience higher stresses at regions of inflection, regardless of wall thickness variation.…”

Imaging and Ageing of the Aorta and Large Arteries in the Lower Extremity

“…Retrospective EKG-gated CT scanning allows also dynamic imaging of the aorta, identifying pulsatile changes in the thoracic and abdominal aorta during the heart cycle [ 39 , 40 ]. CT imaging with fi nite element computational analysis has also been used in attempting the refi nement of the rupture risk assessment [ 41 ]. Another important advancement in recent years in aortic CT imaging is post-processing of the contrast-enhanced images in dedicated workstations.…”