A Technique for Comparing Wall Pressure Distributions in Steady Flow Through Rigid Versus Flexible Patient-based Abdominal Aortic Aneurysm Phantoms

Peattie, Robert A.; Golden, Ethan; Nomoto, Rio; Margossian, C.M.; Pancheri, Francesco Q.; Edgar, Erik S.; Iafrati, Mark D.; Dorfmann, Luis

doi:10.1111/ext.12154

Cited by 3 publications

(4 citation statements)

References 35 publications

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“…Similar findings have also been reported in []. However, experimental measurements have shown wall pressure to be non‐uniform even under steady flow . This finding underscores the importance of need for close coupling of experimental wall pressure measurements to wall stress calculations, in part because of the need to verify CFD analyses and in part because at present there is no general agreement on the most appropriate turbulence model to accurately simulate the low Reynolds number, separated, transitional flows found in AAAs in vivo .…”

Section: Introductionsupporting

confidence: 78%

“…The shape of their pressure distributions versus axial location at systole and diastole were somewhat different from those in the current study, which is expected considering their dissimilar phantom shape. Peattie et al . measured pressure in a similarly‐shaped AAA phantom under steady flow conditions and obtained pressure versus distance curves that varied about 50 % more with axial position than the data shown in Figure a, possibly due to the different shapes of the renal arteries in their model.…”

Section: Resultsmentioning

confidence: 95%

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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: Introductionsupporting

confidence: 78%

Section: Resultsmentioning

confidence: 95%

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

et al. 2018

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“…Previous investigations [15][16][17][18] used phantoms from stiff photopolymers that lack compliance of arteries vital for device placement. To capture the flexible and compliant nature of the arteries, other investigators have followed similar approaches by fabricating a stiff 3D printed cast for silicone or polyurethane injection molding [19][20][21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Method to simulate distal flow resistance in coronary arteries in 3D printed patient specific coronary models

et al. 2020

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Background: Three-dimensional printing (3DP) offers a unique opportunity to build flexible vascular patient-specific coronary models for device testing, treatment planning, and physiological simulations. By optimizing the 3DP design to replicate the geometrical and mechanical properties of healthy and diseased arteries, we may improve the relevance of using such models to simulate the hemodynamics of coronary disease. We developed a method to build 3DP patient specific coronary phantoms, which maintain a significant part of the coronary tree, while preserving geometrical accuracy of the atherosclerotic plaques and allows for an adjustable hydraulic resistance. Methods: Coronary computed tomography angiography (CCTA) data was used within Vitrea (Vital Images, Minnetonka, MN) cardiac analysis application for automatic segmentation of the aortic root, Left Anterior Descending (LAD), Left Circumflex (LCX), Right Coronary Artery (RCA), and calcifications. Stereolithographic (STL) files of the vasculature and calcium were imported into Autodesk Meshmixer for 3D model optimization. A base with three chambers was built and interfaced with the phantom to allow fluid collection and independent distal resistance adjustment of the RCA, LAD and LCX and branching arteries. For the 3DP we used Agilus for the arterial wall, VeroClear for the base and a Vero blend for the calcifications, respectively. Each chamber outlet allowed interface with catheters of varying lengths and diameters for simulation of hydraulic resistance of both normal and hyperemic coronary flow conditions. To demonstrate the manufacturing approach appropriateness, models were tested in flow experiments. Results: Models were used successfully in flow experiments to simulate normal and hyperemic flow conditions. The inherent mean resistance of the chamber for the LAD, LCX, and RCA, were 1671, 1820, and 591 (dynes • sec/ cm 5), respectively. This was negligible when compared with estimates in humans, with the chamber resistance equating to 0.65-5.86%, 1.23-6.86%, and 0.05-1.67% of the coronary resistance for the LAD, LCX, and RCA, respectively at varying flow rates and activity states. Therefore, the chamber served as a means to simulate the compliance of the distal coronary trees and to allow facile coupling with a set of known resistance catheters to simulate various physical activity levels.

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“…Previous investigations have traditionally been fabricated from stiff photopolymers that lack compliance of arteries vital for graft deployment. Many have followed this approach by fabricating a stiff 3D printed cast for silicone or polyurethane injection molding, creating systems to capture the flexible and compliant nature of the arteries [15–20] . However, this method is very time intensive, requiring days for molding, casting, and layering, in addition to producing phantoms with more rigid properties than human vasculature.…”

Section: Introductionmentioning

confidence: 99%

3D printed abdominal aortic aneurysm phantom for image guided surgical planning with a patient specific fenestrated endovascular graft system

et al. 2017

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Following new trends in precision medicine, Juxatarenal Abdominal Aortic Aneurysm (JAAA) treatment has been enabled by using patient-specific fenestrated endovascular grafts. The X-ray guided procedure requires precise orientation of multiple modular endografts within the arteries confirmed via radiopaque markers. Patient-specific 3D printed phantoms could familiarize physicians with complex procedures and new devices in a risk-free simulation environment to avoid periprocedural complications and improve training. Using the Vascular Modeling Toolkit (VMTK), 3D Data from a CTA imaging of a patient scheduled for Fenestrated EndoVascular Aortic Repair (FEVAR) was segmented to isolate the aortic lumen, thrombus, and calcifications. A stereolithographic mesh (STL) was generated and then modified in Autodesk MeshMixer for fabrication via a Stratasys Eden 260 printer in a flexible photopolymer to simulate arterial compliance. Fluoroscopic guided simulation of the patient-specific FEVAR procedure was performed by interventionists using all demonstration endografts and accessory devices. Analysis compared treatment strategy between the planned procedure, the simulation procedure, and the patient procedure using a derived scoring scheme. Results With training on the patient-specific 3D printed AAA phantom, the clinical team optimized their procedural strategy. Anatomical landmarks and all devices were visible under x-ray during the simulation mimicking the clinical environment. The actual patient procedure went without complications. Conclusions With advances in 3D printing, fabrication of patient specific AAA phantoms is possible. Simulation with 3D printed phantoms shows potential to inform clinical interventional procedures in addition to CTA diagnostic imaging.

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A Technique for Comparing Wall Pressure Distributions in Steady Flow Through Rigid Versus Flexible Patient-based Abdominal Aortic Aneurysm Phantoms

Cited by 3 publications

References 35 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

Method to simulate distal flow resistance in coronary arteries in 3D printed patient specific coronary models

3D printed abdominal aortic aneurysm phantom for image guided surgical planning with a patient specific fenestrated endovascular graft system

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