title: Toward an optimal position for inferior vena cava filters: computational modeling of the impact of renal vein inflow with Celect and TrapEase filters.
abstract: OBJECTIVE
  To evaluate the hemodynamic effects of renal vein inflow and filter position on unoccluded and partially occluded inferior vena cava (IVC) filters with use of three-dimensional computational fluid dynamics.
  
  
  METHODS
  Three-dimensional models of the TrapEase and Günther Celect IVC filters, spherical thrombi, and an IVC with renal veins were constructed. Hemodynamics of steady-state flow was examined for unoccluded and partially occluded TrapEase and Günther Celect IVC filters in varying proximity to the renal veins.
  
  
  RESULTS
  Flow past the unoccluded filters demonstrated minimal disruption. Natural regions of stagnant/recirculating flow in the IVC were observed superior to the bilateral renal vein inflows. High flow velocities and elevated shear stresses were observed in the vicinity of renal inflow. Spherical thrombi induce stagnant/recirculating flow downstream of the thrombus. Placement of the TrapEase filter in the suprarenal position resulted in a large area of low shear stress/stagnant flow within the filter just downstream of thrombus trapped in the upstream trapping position.
  
  
  CONCLUSIONS
  Filter position with respect to renal vein inflow influences filter trapping hemodynamics. Placement of the TrapEase filter in a suprarenal location may be thrombogenic, with redundant areas of stagnant/recirculating flow and low shear stress along the caval wall caused by the upstream trapping position and the naturally occurring region of stagnant flow from the renal veins. Infrarenal vein placement of IVC filters in a near-juxtarenal position with the downstream cone near the renal vein inflow likely confers increased levels of mechanical lysis of trapped thrombi from increased shear stress from renal vein inflow.
authors.affiliation: Division of Vascular and Interventional Radiology, Kaiser Permanente Santa Clara Medical Center, Santa Clara, California 95051, USA. stephen.wang@alumni.duke.edu
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Wang
authors.forename: Michael A
authors.initials: MA
authors.lastname: Singer
mesh_terms: D001783:Blood Flow Velocity; D003198:Computer Simulation; D019544:Equipment Failure Analysis; D006801:Humans; D008955:Models, Cardiovascular; D011474:Prosthesis Design; D019919:Prosthesis Implantation / Q000379:methods*; D012079:Renal Circulation / Q000502:physiology*; D012082:Renal Veins / Q000502:physiology*; D016306:Vena Cava Filters