scholarly journals Stability of Membrane Elastodynamics with Applications to Cylindrical Aneurysms

2011 ◽  
Vol 2011 ◽  
pp. 1-24 ◽  
Author(s):  
A. Samuelson ◽  
P. Seshaiyer

The enlargement and rupture of intracranial and abdominal aortic aneurysms constitutes a major medical problem. It has been suggested that enlargement and rupture are due to mechanical instabilities of the associated complex fluid-solid interaction in the lesions. In this paper, we examine a coupled fluid-structure mathematical model for a cylindrical geometry representing an idealized aneurysm using both analytical and numerical techniques. A stability analysis for this subclass of aneurysms is presented. It is shown that this subclass of aneurysms is dynamically stable both with and without a viscoelastic contribution to the arterial wall.

Author(s):  
Giacomo Marini ◽  
Andreas Maier ◽  
Christian Reeps ◽  
Hans-Henning Eckstein ◽  
Wolfgang A. Wall ◽  
...  

2015 ◽  
Vol 27 (02) ◽  
pp. 1650017 ◽  
Author(s):  
Maria G. C. Nestola ◽  
Alessio Gizzi ◽  
Christian Cherubini ◽  
Simonetta Filippi

Computational modeling plays an important role in biology and medicine to assess the effects of hemodynamic alterations in the onset and development of vascular pathologies. Synthetic analytic indices are of primary importance for a reliable and effective a priori identification of the risk. In this scenario, we propose a multiscale fluid-structure interaction (FSI) modeling approach of hemodynamic flows, extending the recently introduced three-band decomposition (TBD) analysis for moving domains. A quantitative comparison is performed with respect to the most common hemodynamic risk indicators in a systematic manner. We demonstrate the reliability of the TBD methodology also for deformable domains by assuming a hyperelastic formulation of the arterial wall and a Newtonian approximation of the blood flow. Numerical simulations are performed for physiologic and pathologic axially symmetric geometry models with particular attention to abdominal aortic aneurysms (AAAs). Risk assessment, limitations and perspectives are finally discussed.


2020 ◽  
Vol 22 (2) ◽  
pp. 187-193 ◽  
Author(s):  
Pinelopi Rafouli‐Stergiou ◽  
Ignatios Ikonomidis ◽  
Niki Katsiki ◽  
Nikolaos P. E. Kadoglou ◽  
Stefanos Vlachos ◽  
...  

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
I Ikonomidis ◽  
P Rafouli-Stergiou ◽  
N Katsiki ◽  
N Kadoglou ◽  
S Vlachos ◽  
...  

Abstract Introduction Pulse wave velocity (PWV) is a valid, clinically feasible marker of arterial stiffening, and a strong predictor of outcomes. In patients with abdominal aortic aneurysms (AAA) alterations in arterial wall composition and inflammation were proposed as possible contributors to increased arterial stiffness. Purpose The present study aimed to compare aortic elastic properties in patients with abdominal aortic aneurysms (AAA), with or without coronary artery disease (CAD), as well as healthy individuals. Methods A total of 130 patients with AAA, eligible for interventional repair, and 30 healthy individuals, comprising the control group (HC), were evaluated. Study groups did not differ in anthropometrical characteristics and CV risk factors. Presence of CAD was identified by coronary angiography. Aortic PWV (aPWV) was measured using the Arteriograph method. Results aPWV was found considerably higher in AAA patients compared to HC group (11.5±2.9 vs. 7.3±1.6 m/s, p<0.001), after adjustment for age, sex and mean arterial pressure (MAP). Interestingly, among patients with AAA, those with concomitant CAD (n=41) had higher aPWV than those without CAD (12.5±2.9 vs. 11.0±3.0 m/s, p=0.03), after adjustment for age, sex and MAP. In receiver-operator-curve (ROC) analysis, the area under the curve (AUC) of aPWV for the prediction of CAD presence in the AAA study group was 0.72 [95% confidence interval (CI): 0.55–0.84, p=0.03]. According to this, the best cut-off was a value of aPWV above 12.8 m/s (78% sensitivity and 73% specificity). This cut-off was identified as a significant predictor of CAD presence in the AAA study population according to univariate logistic regression analysis (OR=2.51, 95% CI: 1.79–5.19, p=0.02). After adjustment for age, sex, dyslipidemia, smoking and MAP in multivariate logistic regression analysis, the cut-off aPWV level remained independently associated with the presence of CAD (OR=1.64, 95% CI: 1.19–4.08, p=0.03). Conclusion The co-existence of CAD and AAA is characterized by a greater arterial stiffness. This finding supports a role of measuring arterial stiffness markers when evaluating AAA patients' cardiovascular risk and selecting endovascular stents with more favorable elastic properties. Further studies are needed to explore whether aPWV values could be used to as a screening tool to detect CAD or to guide treatment in AAA patients. Funding Acknowledgement Type of funding source: None


2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
B. Rodriguez-Vila ◽  
J. Tarjuelo-Gutierrez ◽  
P. Sánchez-González ◽  
P. Verbrugghe ◽  
I. Fourneau ◽  
...  

A correct patient-specific identification of the abdominal aortic aneurysm is useful for both diagnosis and treatment stages, as it locates the disease and represents its geometry. The actual thickness and shape of the arterial wall and the intraluminal thrombus are of great importance when predicting the rupture of the abdominal aortic aneurysms. The authors describe a novel method for delineating both the internal and external contours of the aortic wall, which allows distinguishing between vessel wall and intraluminal thrombus. The method is based on active shape model and texture statistical information. The method was validated with eight MR patient studies. There was high correspondence between automatic and manual measurements for the vessel wall area. Resulting segmented images presented a mean Dice coefficient with respect to manual segmentations of 0.88 and a mean modified Hausdorff distance of 1.14 mm for the internal face and 0.86 and 1.33 mm for the external face of the arterial wall. Preliminary results of the segmentation show high correspondence between automatic and manual measurements for the vessel wall and thrombus areas. However, since the dataset is small the conclusions cannot be generalized.


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