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Computational analysis of renal artery flow characteristics by modeling aortoplasty and aortic bypass interventions for abdominal aortic coarctation

Research output: Contribution to journalArticle

Christopher Tossas-Betancourt, Theodorus M.J. van Bakel, Christopher J. Arthurs, Dawn M. Coleman, Jonathan L. Eliason, C. Alberto Figueroa, James C. Stanley

Original languageEnglish
Pages (from-to)505-516.e4
JournalJournal of Vascular Surgery
Volume71
Issue number2
Early online date29 May 2019
DOIs
Publication statusPublished - 1 Feb 2020

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Abstract

Objective:Suprarenal abdominal aortic coarctation (SAAC) alters flow and pressure patterns to the kidneys and is often associated with severe angiotensin-mediated hypertension refractory to drug therapy. SAAC is most often treated by a thoracoabdominal bypass (TAB) or patch aortoplasty (PA). It is currently unclear what effect these interventions have on renal flow and pressure waveforms. This study, using retrospective data from a patient with SAAC subjected to a TAB, undertook computational modeling to analyze aortorenal blood flow preoperatively as well as postoperatively after a variety of TAB and PA interventions. Methods:Patient-specific anatomic models were constructed from preoperative computed tomography angiograms of a 9-year-old child with an isolated SAAC. Fluid-structure interaction (FSI) simulations of hemodynamics were performed to analyze preoperative renal flow and pressure waveforms. A parametric study was then performed to examine the hemodynamic impact of different bypass diameters and patch oversizing. Results:Preoperative FSI results documented diastole-dominated renal perfusion with considerable high-frequency disturbances in blood flow and pressure. The postoperative TAB right and left kidney volumes increased by 58% and 79%, respectively, reflecting the increased renal artery blood flows calculated by the FSI analysis. Postoperative increases in systolic flow accompanied decreases in high-frequency disturbances, aortic pressure, and collateral flow after all surgical interventions. In general, lesser degrees of high-frequency disturbances followed PA interventions. High-frequency disturbances were eliminated with the 0% PA in contrast to the 30% and 50% PA oversizing and TAB interventions, in which these flow disturbances remained. Conclusions:Both TAB and PA dramatically improved renal artery flow and pressure waveforms, although disturbed renal waveforms remained in many of the surgical scenarios. Importantly, only the 0% PA oversizing scenario eliminated all high-frequency disturbances, resulting in nearly normal aortorenal blood flow. The study also establishes the relevance of patient-specific computational modeling in planning interventions for the midaortic syndrome. Clinical Relevance:We performed computational fluid dynamics modeling to assess aortorenal blood flow in a child with a suprarenal abdominal aortic coarctation and to test the performance of different surgical interventions. We discovered high-frequency disturbances in the renal arteries that could potentially trigger excessive renin release. Thoracoabdominal bypass and patch aortoplasty with oversizing did not remove these disturbances completely. This could explain why the hypertension cure rates of surgical repair of suprarenal abdominal aortic coarctation are suboptimal. In addition, this study establishes the relevance of computational fluid dynamics modeling as a valuable tool to analyze complex hemodynamics and to test the performance of different surgical interventions.

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