title: Hemodynamics in coronary arteries with overlapping stents.
abstract: Coronary artery stenosis is commonly treated by stent placement via percutaneous intervention, at times requiring multiple stents that may overlap. Stent overlap is associated with increased risk of adverse clinical outcome. While changes in local blood flow are suspected to play a role therein, hemodynamics in arteries with overlapping stents remain poorly understood. In this study we analyzed six cases of partially overlapping stents, placed ex vivo in porcine left coronary arteries and compared them to five cases with two non-overlapping stents. The stented vessel geometries were obtained by micro-computed tomography of corrosion casts. Flow and shear stress distribution were calculated using computational fluid dynamics. We observed a significant increase in the relative area exposed to low wall shear stress (WSS<0.5 Pa) in the overlapping stent segments compared both to areas without overlap in the same samples, as well as to non-overlapping stents. We further observed that the configuration of the overlapping stent struts relative to each other influenced the size of the low WSS area: positioning of the struts in the same axial location led to larger areas of low WSS compared to alternating struts. Our results indicate that the overlap geometry is by itself sufficient to cause unfavorable flow conditions that may worsen clinical outcome. While stent overlap cannot always be avoided, improved deployment strategies or stent designs could reduce the low WSS burden.
authors.affiliation: Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland.
authors.forename: Farhad
authors.initials: F
authors.lastname: Rikhtegar
authors.affiliation: Clinic of Cardiology, University Hospital Zurich, Zurich, Switzerland.
authors.forename: Christophe
authors.initials: C
authors.lastname: Wyss
authors.affiliation: Institute for Biomechanics, Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland.
authors.forename: Kathryn S
authors.initials: KS
authors.lastname: Stok
authors.affiliation: Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland.
authors.forename: Dimos
authors.initials: D
authors.lastname: Poulikakos
authors.affiliation: Institute for Biomechanics, Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland.
authors.forename: Ralph
authors.initials: R
authors.lastname: Müller
authors.affiliation: Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland; The Interface Group, Institute of Physiology, University of Zurich, Winterthurerstrasse 190, Y23 J8, 8057 Zurich, Switzerland. Electronic address: vartan.kurtcuoglu@uzh.ch.
authors.forename: Vartan
authors.initials: V
authors.lastname: Kurtcuoglu
mesh_terms: D000818:Animals; D001158:Arteries / Q000502:physiology; D003198:Computer Simulation; D003331:Coronary Vessels / Q000502:physiology*; D006439:Hemodynamics; D057446:Hydrodynamics; D008955:Models, Cardiovascular; D015607:Stents; D013314:Stress, Mechanical; D013552:Swine
keywords: Hemodynamics; Restenosis; Stent overlap; Thrombosis; Wall shear stress