Experimental and computational investigation of the patient-specific abdominal aortic aneurysm pressure field

Antón, Raúl; Chen, Chia Yuan; Hung, Ming-yang; Finol, Ender A.; Pekkan, Kerem

doi:10.1080/10255842.2013.865024

Cited by 29 publications

(15 citation statements)

References 29 publications

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“…One feature common to many patients is the formation of one or more coherent vortices at the proximal end of each aneurysm that can convect through the bulge during the flow cycle and impact the distal bulge wall . Experiments interrogating flow in idealized and patient‐based phantoms are consistent with this observation, but have also shown the flow to be highly unstable under both steady and pulsatile conditions, even at low values of Reynolds and Womersley numbers that characterize the in vivo abdominal aorta at rest . The time scale of some instabilities even exceeds the length of the cardiac cycle, making certain AAA flows non‐periodic .…”

Section: Introductionmentioning

confidence: 66%

Pulsatile flow measurements and wall stress distribution in a patient specific abdominal aortic aneurysm phantom

et al. 2018

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In this study, we develop a physiologic internal pressure and wall stress analysis procedure and apply it to a patient-specific abdominal aortic aneurysm model. Timedependent pressure loading of the inner vessel wall was experimentally measured in a 3D printed aneurysm phantom. The results were used as boundary conditions for finite element calculations of von Mises stresses throughout the AAA model over the cardiac cycle. A nonlinear hyperelastic constitutive law with parameters based on biaxial stress-deformation data from aneurysmal tissue samples was used to describe the mechanical behavior of the aneurysm wall. The internal pressure was found to be fairly spatially uniform (within 10%) over most of the cardiac cycle, but average internal pressure varied by more than a factor of two between systole and diastole. The aneurysm wall stress was highly spatially nonuniform. The highest value of von Mises stress was localized in a small area within the aneurysm bulge and remained in the same place throughout the cardiac cycle, suggesting that this area was the most likely point of rupture. Large variations in wall stress over the cardiac cycle suggest calculations that assume steady flow are a poor approximation for physiological stresses. K E Y W O R D SAAA, abdominal aortic aneurysm, finite element analysis, flow field measurements 2258

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Section: Introductionmentioning

confidence: 66%

Pulsatile flow measurements and wall stress distribution in a patient specific abdominal aortic aneurysm phantom

et al. 2018

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“…In addition, for the PIV data validation, a correlation coefficient value was calculated to Fig. 2 Schematic representation of stereoscopic PIV configuration [45] show…”

Section: Numerical Modeling Methodsmentioning

confidence: 99%

Effects of Intraluminal Thrombus on Patient-Specific Abdominal Aortic Aneurysm Hemodynamics via Stereoscopic Particle Image Velocity and Computational Fluid Dynamics Modeling

Chen

Antón

Hung

et al. 2014

Journal of Biomechanical Engineering

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The pathology of the human abdominal aortic aneurysm (AAA) and its relationship to the later complication of intraluminal thrombus (ILT) formation remains unclear. The hemodynamics in the diseased abdominal aorta are hypothesized to be a key contributor to the formation and growth of ILT. The objective of this investigation is to establish a reliable 3D flow visualization method with corresponding validation tests with high confidence in order to provide insight into the basic hemodynamic features for a better understanding of hemodynamics in AAA pathology and seek potential treatment for AAA diseases. A stereoscopic particle image velocity (PIV) experiment was conducted using transparent patient-specific experimental AAA models (with and without ILT) at three axial planes. Results show that before ILT formation, a 3D vortex was generated in the AAA phantom. This geometry-related vortex was not observed after the formation of ILT, indicating its possible role in the subsequent appearance of ILT in this patient. It may indicate that a longer residence time of recirculated blood flow in the aortic lumen due to this vortex caused sufficient shear-induced platelet activation to develop ILT and maintain uniform flow conditions. Additionally, two computational fluid dynamics (CFD) modeling codes (Fluent and an in-house cardiovascular CFD code) were compared with the two-dimensional, threecomponent velocity stereoscopic PIV data. Results showed that correlation coefficients of the out-of-plane velocity data between PIV and both CFD methods are greater than 0.85, demonstrating good quantitative agreement. The stereoscopic PIV study can be utilized as test case templates for ongoing efforts in cardiovascular CFD solver development. Likewise, it is envisaged that the patient-specific data may provide a benchmark for further studying hemodynamics of actual AAA, ILT, and their convolution effects under physiological conditions for clinical applications.

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“…Due to difficulties of physical experiments, FEA is employed to calculate the AAA wall stress distribution. Thus, several parameters related to the AAA geometry [9][10][11], the material properties [12,13], the inclusion of intraluminal thrombus [14], and other biomechanical factors [15][16][17] have been investigated.…”

Section: Introductionmentioning

confidence: 99%

A Methodology for Verifying Abdominal Aortic Aneurysm Wall Stress

Galarreta

Cazón

Antón

et al. 2016

Journal of Biomechanical Engineering

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An abdominal aortic aneurysm (AAA) is a permanent focal dilatation of the abdominal aorta of at least 1.5 times its normal diameter. Although the criterion of maximum diameter is still used in clinical practice to decide on a timely intervention, numerical studies have demonstrated the importance of other geometric factors. However, the major drawback of numerical studies is that they must be validated experimentally before clinical implementation. This work presents a new methodology to verify wall stress predicted from the numerical studies against the experimental testing. To this end, four AAA phantoms were manufactured using vacuum casting. The geometry of each phantom was subject to microcomputed tomography (μCT) scanning at zero and three other intraluminal pressures: 80, 100, and 120 mm Hg. A zero-pressure geometry algorithm was used to calculate the wall stress in the phantom, while the numerical wall stress was calculated with a finite-element analysis (FEA) solver based on the actual zero-pressure geometry subjected to 80, 100, and 120 mm Hg intraluminal pressure loading. Results demonstrate the moderate accuracy of this methodology with small relative differences in the average wall stress (1.14%). Additionally, the contribution of geometric factors to the wall stress distribution was statistically analyzed for the four phantoms. The results showed a significant correlation between wall thickness and mean curvature (MC) with wall stress.

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Experimental and computational investigation of the patient-specific abdominal aortic aneurysm pressure field

Cited by 29 publications

References 29 publications

Pulsatile flow measurements and wall stress distribution in a patient specific abdominal aortic aneurysm phantom

Pulsatile flow measurements and wall stress distribution in a patient specific abdominal aortic aneurysm phantom

Effects of Intraluminal Thrombus on Patient-Specific Abdominal Aortic Aneurysm Hemodynamics via Stereoscopic Particle Image Velocity and Computational Fluid Dynamics Modeling

A Methodology for Verifying Abdominal Aortic Aneurysm Wall Stress

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