title: Hemodynamics and in-stent restenosis: micro-CT images, histology, and computer simulations.
abstract: A model that combines the results of in vivo experiment, 3D image data, and computer simulation has been developed. Twelve identical stents were implanted into six healthy pigs and explanted at a range of different post-recovery periods from 6 h to 28 days. The stented vessel segments were embedded in methacrylate resin for the preparation of transverse histological sections and imaged using ultra-high resolution micro-CT. The resulting CT data was used to reconstruct the 3D geometry of the stents and one case was used to inform a 3D computational fluid dynamic model. Derived hemodynamic parameters such as wall shear stress (WSS), axial WSS, and oscillatory shear index were correlated with the distribution of neointimal hyperplasia, assessed from histomorphometric analyses. The direct comparison of hemodynamic parameters and biological response supports the hypothesis that low and oscillatory WSS lead to a greater neointimal response within the stented region. Moreover, the realistic geometry obtained from micro-CT images, characterized by proximal overexpansion and asymmetric deployment of the stent, leads to a markedly non-uniform distribution of WSS values and correlates with asymmetric neo-intimal growth. This correlation cannot be appreciated from studies of idealized geometries.
authors.affiliation: Laboratory of Biological Structure Mechanics, Structural Engineering Department, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milan, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Morlacchi
authors.forename: Brandis
authors.initials: B
authors.lastname: Keller
authors.forename: Patrizia
authors.initials: P
authors.lastname: Arcangeli
authors.forename: Marta
authors.initials: M
authors.lastname: Balzan
authors.forename: Francesco
authors.initials: F
authors.lastname: Migliavacca
authors.forename: Gabriele
authors.initials: G
authors.lastname: Dubini
authors.forename: Julian
authors.initials: J
authors.lastname: Gunn
authors.forename: Nadine
authors.initials: N
authors.lastname: Arnold
authors.forename: Andrew
authors.initials: A
authors.lastname: Narracott
authors.forename: David
authors.initials: D
authors.lastname: Evans
authors.forename: Patricia
authors.initials: P
authors.lastname: Lawford
mesh_terms: D000818:Animals; D003198:Computer Simulation; D006083:Graft Occlusion, Vascular / Q000503:physiopathology*; D006439:Hemodynamics / Q000502:physiology*; D006965:Hyperplasia / Q000503:physiopathology*; D021621:Imaging, Three-Dimensional; D023421:Models, Animal; D008955:Models, Cardiovascular; D015607:Stents / Q000009:adverse effects*; D013312:Stress, Physiological / Q000502:physiology; D025321:Surgery, Computer-Assisted; D013552:Swine; D055114:X-Ray Microtomography