Abstract 17040: Portico Stent Durability Driven from Anatomical Assessments of TAVR Patients
Background: Transcatheter aortic valve replacement (TAVR) procedures are increasingly used to treat elderly patients with aortic stenosis. To ensure clinical safety, valve and stent frame durability is critical. Current FDA guidance requires stent frames to be durable to a minimum of 15 year equivalent life for safety. Hence, an understanding of the anatomy and its impact on stent frame durability is necessary. In this study, the steps taken to understand, quantify and test the Portico valve (St Jude Medical, St Paul, MN) stent frame is discussed.
Methods: CT scans from representative TAVR patients (N = 52) were used to quantify deformation modes in the aortic anatomy. These scans were segmented and analyzed using 3Mensio Medical Imaging (3Mensio, Netherlands) and Solidworks (Dassault Systems, MA). The deformation modes were then translated to strain levels using finite element analysis (ABAQUS, Dassault Systems) to obtain test parameters for bench testing. Thirty samples were tested to these minimum strain levels using proprietary test methods to at least 600M cycles for stent durability.
Results: Using CT analysis from representative TAVR patients, six different deformation modes were identified. The modes include radial and elliptical distension, axial elongation, bending of the aortic arch anatomy, torsion, and hydrodynamic load on the valve (confirmed using bench testing). The deformation is driven by cardiac motion between systole and diastole. The measured distensions are comparable to available minimal literature data.
FEA simulations were used to predict the alternating and mean strains at the measured distensions for the six modes. Thirty samples were successfully tested to these strain levels for stent durability to 600M cycles (15 year equivalent life).
Conclusions: The Portico stent frame has been successfully tested at or beyond expected in vivo strain levels. Thus, the device is safe to use in clinical applications of the product.
Author Disclosures: S. Kumar: None. G. Satam: None. K. Vietmeier: None.
- © 2014 by American Heart Association, Inc.