title: Mechanical analysis of ovine and pediatric pulmonary artery for heart valve stent design.
abstract: Transcatheter heart valve replacement is an attractive and promising technique for congenital as well as acquired heart valve disease. In this procedure, the replacement valve is mounted in a stent that is expanded at the aimed valve position and fixated by clamping. However, for this technique to be appropriate for pediatric patients, the material properties of the host tissue need to be determined to design stents that can be optimized for this particular application. In this study we performed equibiaxial tensile tests on four adult ovine pulmonary artery walls and compared the outcomes with one pediatric pulmonary artery. Results show that the pediatric pulmonary artery was significantly thinner (1.06 ± 0.36 mm (mean ± SD)) than ovine tissue (2.85 ± 0.40 mm), considerably stiffer for strain values that exceed the physiological conditions (beyond 50% strain in the circumferential and 60% in the longitudinal direction), more anisotropic (with a significant difference in stiffness between the longitudinal and circumferential directions beyond 60% strain) and presented stronger non-linear stress-strain behavior at equivalent strains (beyond 26% strain) compared to ovine tissue. These discrepancies suggest that stents validated and optimized using the ovine pre-clinical model might not perform satisfactorily in pediatric patients. The material parameters derived from this study may be used to develop stent designs for both applications using computational models.
authors.affiliation: Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands. M.S.Cabrera@tue.nl
authors.forename: M S
authors.initials: MS
authors.lastname: Cabrera
authors.forename: C W J
authors.initials: CW
authors.lastname: Oomens
authors.forename: C V C
authors.initials: CV
authors.lastname: Bouten
authors.forename: A J J C
authors.initials: AJ
authors.lastname: Bogers
authors.forename: S P
authors.initials: SP
authors.lastname: Hoerstrup
authors.forename: F P T
authors.initials: FP
authors.lastname: Baaijens
mesh_terms: D000328:Adult; D000818:Animals; D002675:Child, Preschool; D004548:Elasticity; D006350:Heart Valve Prosthesis; D006801:Humans; D008955:Models, Cardiovascular; D011474:Prosthesis Design; D011651:Pulmonary Artery / Q000502:physiology*; D012756:Sheep; D015607:Stents; D013718:Tensile Strength
keywords: Biaxial tensile test; Constitutive modeling; Heart valve replacement; Pediatric stent design; Pulmonary artery