title: Hemodynamics of the renal artery ostia with implications for their structural development and efficiency of flow.
abstract: BACKGROUND
  Energy losses at tube or blood vessel orifices depend on the extent of flare as measured by the dimensionless ratio of the fillet radius of curvature to diameter (r/D).
  
  
  OBJECTIVE
  The goal of this study was to assess the effect of ostial fillet radii on energy losses at the aorta-renal artery junctions since as much as a quarter of cardiac output passes through the kidneys.
  
  
  METHODS
  Pressure loss coefficients K for the renal artery ostia as a function of r/D have been determined for representative anatomical variants using finite volume simulations. Estimates of fillet radii in humans from image analysis were employed in simulations for comparison of loss coefficients.
  
  
  RESULTS
  Values for K drop 45% as r/D increases over the range 0-1.3. Image analysis indicates that the ostia are not symmetric in humans with (r/D)superior much larger than (r/D)inferior. Simulations show the loss coefficient depends almost entirely on the superior fillet radius.
  
  
  CONCLUSIONS
  Superior fillet radii for both renal arteries are similar to the optimal value to reduce energy losses while the inferior radii are not. Ostial asymmetry may have been induced by higher levels of shear stress present on the superior portion of a developing symmetric ostium of small r/D.
authors.affiliation: School of Chemical, Biological and Materials Engineering, University of Oklahoma, 100 E. Boyd SEC T301, Norman, OK, 73019, USA.
authors.forename: William H
authors.initials: WH
authors.lastname: McIntosh
authors.affiliation: School of Chemical, Biological and Materials Engineering, University of Oklahoma, 100 E. Boyd SEC T301, Norman, OK, 73019, USA.
authors.forename: Mesude
authors.initials: M
authors.lastname: Ozturk
authors.affiliation: School of Chemical, Biological and Materials Engineering, University of Oklahoma, 100 E. Boyd SEC T301, Norman, OK, 73019, USA.|Bioengineering Program, University of Oklahoma, 100 E. Boyd SEC T301, Norman, OK, 73019, USA.
authors.forename: Linden A
authors.initials: LA
authors.lastname: Down
authors.affiliation: School of Chemical, Biological and Materials Engineering, University of Oklahoma, 100 E. Boyd SEC T301, Norman, OK, 73019, USA.
authors.forename: Dimitrios V
authors.initials: DV
authors.lastname: Papavassiliou
authors.affiliation: School of Chemical, Biological and Materials Engineering, University of Oklahoma, 100 E. Boyd SEC T301, Norman, OK, 73019, USA.|Bioengineering Program, University of Oklahoma, 100 E. Boyd SEC T301, Norman, OK, 73019, USA.
authors.forename: Edgar A
authors.initials: EA
authors.lastname: O'Rear
mesh_terms: D001011:Aorta / Q000033:anatomy & histology* / Q000254:growth & development / Q000502:physiology*; D001783:Blood Flow Velocity; D002302:Cardiac Output; D003198:Computer Simulation; D006439:Hemodynamics; D006801:Humans; D008953:Models, Anatomic; D008955:Models, Cardiovascular; D012077:Renal Artery / Q000033:anatomy & histology* / Q000254:growth & development / Q000502:physiology*
keywords: Blood flow; computational fluid dynamics; developmental biology; pressure loss coefficient