title: The effect of stent graft oversizing on radial forces considering nitinol wire behavior and vessel characteristics.
abstract: Stent graft fixation in the vessel affects the success of endovascular aneurysm repair. Thereby the radial forces of the stent, which are dependent on several factors, play a significant role. In the presented work, a finite element sensitivity study was performed. The radial forces are 29% lower when using the hyperelastic approach for the vessel compared with linear elastic assumptions. Without the linear elastic modeled plaque, the difference increases to 35%. Modeling plaque with linear elastic material approach results in 8% higher forces than with a hyperelastic characteristic. The significant differences resulting from the investigated simplifications of the material lead to the conclusion that it is important to apply an anisotropic nonlinear approach for the vessel. The oversizing study shows that radial forces increase by 64% (0.54 N) when raising the oversize from 10 to 22%, and no further increase in force can be observed beyond these values (vessel diameter D=12 mm). Starting from an oversize of 24%, the radial force steadily decreases. The findings of the investigation show that besides the oversizing the material properties, the ring design and the vessel characteristics have an influence on radial forces.
authors.affiliation: Fraunhofer Institute for Machine Tools and Forming Technologies, Dresden, Germany. Electronic address: bjoern.senf@iwu.fraunhofer.de.
authors.forename: B
authors.initials: B
authors.lastname: Senf
authors.affiliation: Innovation Center Computer Assisted Surgery, Leipzig, Germany.
authors.forename: S
authors.initials: S
authors.lastname: von Sachsen
authors.affiliation: Fraunhofer Institute for Machine Tools and Forming Technologies, Dresden, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Neugebauer
authors.affiliation: Fraunhofer Institute for Machine Tools and Forming Technologies, Dresden, Germany.
authors.forename: W-G
authors.initials: WG
authors.lastname: Drossel
authors.affiliation: Weisseritztal-Kliniken GmbH, Freital, Germany.
authors.forename: H-J
authors.initials: HJ
authors.lastname: Florek
authors.affiliation: Innovation Center Computer Assisted Surgery, Leipzig, Germany; Herzzentrum Leipzig GmbH, University Hospital, Leipzig, Germany.
authors.forename: F W
authors.initials: FW
authors.lastname: Mohr
authors.affiliation: Herzzentrum Leipzig GmbH, University Hospital, Leipzig, Germany; Mount Sinai Hospital, Cardiothoracic Surgery, New York, USA.
authors.forename: C D
authors.initials: CD
authors.lastname: Etz
mesh_terms: D000497:Alloys; D001696:Biomechanical Phenomena; D001808:Blood Vessels; D020342:Finite Element Analysis; D055595:Mechanical Phenomena; D015607:Stents; D035501:Uncertainty
chemical_list: D000497:Alloys; C013616:nitinol
keywords: Endovascular surgery; Finite element analysis; Stent graft oversizing; Surgical planning