As endovascular treatment of abdominal aortic aneurysms (AAAs) gains popularity, it is becoming possible to treat certain challenging aneurysmal anatomies with endografts relying on suprarenal fixation. In such anatomies, the bare struts of the device may be placed across the renal artery ostia, causing partial obstruction to renal artery blood flow. Computational fluid dynamics (CFD) was used to simulate blood flow from the aorta to the renal arteries, utilizing patient-specific boundary conditions, in three patient models and calculate the degree of shear-based blood damage (hemolysis). We used contrast-enhanced computed tomography angiography (CTA) data from three AAA patients who were treated with a novel endograft to build patient-specific models. For each of the three patients, we constructed a baseline model and endoframe model. The baseline model was a direct representation of the patient’s 30-day post-operative CTA data. This model was then altered to create the endoframe model, which included a ring of metallic struts across the renal artery ostia. CFD was used to simulate blood flow, utilizing patient-specific boundary conditions. Pressures, flows, shear stresses, and the normalized index of hemolysis (NIH) were quantified for all patients. The overall differences between the baseline and endoframe models for all three patients were minimal, as measured though pressure, volumetric flow, velocity, and shear stress. The average NIH across the three baseline and endoframe models was 0.002 and 0.004, respectively. Results of CFD modeling show that the overall disturbance to flow caused by the presence of the endoframe struts is minimal. The magnitude of the NIH in all models was well below the accepted design and safety threshold for implantable medical devices that interact with blood flow.
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February 2012
Research Papers
Computational Modeling of Shear-Based Hemolysis Caused by Renal Obstruction
Polina A. Segalova,
e-mail: polina@stanford.edu
Polina A. Segalova
Department of Mechanical Engineering, Stanford University, Stanford, CA 94305; James H. Clark Center, E350,318 Campus Drive
, Stanford, CA 94305
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K. T. Venkateswara Rao,
K. T. Venkateswara Rao
Nellix Endovascular
, Palo Alto, CA 94303
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Christopher K. Zarins,
Christopher K. Zarins
Department of Surgery,Stanford University
, Stanford, CA 94305
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Charles A. Taylor
Charles A. Taylor
Department of Bioengineering,Stanford University
, Stanford, CA 94305
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Polina A. Segalova
Department of Mechanical Engineering, Stanford University, Stanford, CA 94305; James H. Clark Center, E350,318 Campus Drive
, Stanford, CA 94305e-mail: polina@stanford.edu
K. T. Venkateswara Rao
Nellix Endovascular
, Palo Alto, CA 94303
Christopher K. Zarins
Department of Surgery,Stanford University
, Stanford, CA 94305
Charles A. Taylor
Department of Bioengineering,Stanford University
, Stanford, CA 94305J Biomech Eng. Feb 2012, 134(2): 021003 (7 pages)
Published Online: March 19, 2012
Article history
Received:
July 7, 2011
Revised:
January 16, 2012
Posted:
January 30, 2012
Published:
March 14, 2012
Online:
March 19, 2012
Citation
Segalova, P. A., Venkateswara Rao, K. T., Zarins, C. K., and Taylor, C. A. (March 19, 2012). "Computational Modeling of Shear-Based Hemolysis Caused by Renal Obstruction." ASME. J Biomech Eng. February 2012; 134(2): 021003. https://doi.org/10.1115/1.4005850
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