title: Flow disturbances in stent-related coronary evaginations: a computational fluid-dynamic simulation study.
abstract: OBJECTIVE
  Angiographic ectasias and aneurysms in stented segments have been associated with late stent thrombosis. Using optical coherence tomography (OCT), some stented segments show coronary evaginations reminiscent of ectasias. The purpose of this study was to explore, using computational fluid-dynamic (CFD) simulations, whether OCT-detected coronary evaginations can induce local changes in blood flow.
  
  
  RESULTS
  OCT-detected evaginations are defined as outward bulges in the luminal vessel contour between struts, with the depth of the bulge exceeding the actual strut thickness. Evaginations can be characterised cross-sectionally by depth and along the stented segment by total length. Assuming an ellipsoid shape, we modelled 3-D evaginations with different sizes by varying the depth from 0.2-1.0 mm, and the length from 1-9 mm. For the flow simulation we used average flow velocity data from non-diseased coronary arteries. The change in flow with varying evagination sizes was assessed using a particle tracing test where the particle transit time within the segment with evagination was compared with that of a control vessel. The presence of the evagination caused a delayed particle transit time which increased with the evagination size. The change in flow consisted locally of recirculation within the evagination, as well as flow deceleration due to a larger lumen - seen as a deflection of flow towards the evagination.
  
  
  CONCLUSIONS
  CFD simulation of 3-D evaginations and blood flow suggests that evaginations affect flow locally, with a flow disturbance that increases with increasing evagination size.
authors.affiliation: The Heart Centre, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark.
authors.forename: Maria D
authors.initials: MD
authors.lastname: Radu
authors.forename: Aloïs
authors.initials: A
authors.lastname: Pfenniger
authors.forename: Lorenz
authors.initials: L
authors.lastname: Räber
authors.forename: Stefano F
authors.initials: SF
authors.lastname: de Marchi
authors.forename: Dominik
authors.initials: D
authors.lastname: Obrist
authors.forename: Henning
authors.initials: H
authors.lastname: Kelbæk
authors.forename: Stephan
authors.initials: S
authors.lastname: Windecker
authors.forename: Patrick W
authors.initials: PW
authors.lastname: Serruys
authors.forename: Rolf
authors.initials: R
authors.lastname: Vogel
mesh_terms: D001783:Blood Flow Velocity; D003198:Computer Simulation; D003331:Coronary Vessels / Q000473:pathology / Q000503:physiopathology*; D004108:Dilatation, Pathologic / Q000503:physiopathology; D054855:Drug-Eluting Stents; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D008955:Models, Cardiovascular; D041623:Tomography, Optical Coherence