title: How Can We Help a Patient With a Small Failing Bioprosthesis?: An In Vitro Case Study.
abstract: OBJECTIVE
  The aim of this study was to investigate the hemodynamic performance of a transcatheter heart valve (THV) deployed at different valve-in-valve positions in an in vitro model using a small surgical bioprosthesis.
  
  
  BACKGROUND
  Patients at high surgical risk with failing 19-mm surgical aortic bioprostheses are not candidates for valve-in-valve transcatheter aortic valve replacement, because of risk for high transvalvular pressure gradients (TVPGs) and patient-prosthesis mismatch.
  
  
  METHODS
  A 19-mm stented aortic bioprosthesis was mounted into the aortic chamber of a pulse duplicator, and a 23-mm low-profile balloon-expandable THV was deployed (valve-in-valve) in 4 positions: normal (bottom of the THV stent aligned with the bottom of the surgical bioprosthesis sewing ring) and 3, 6, and 8 mm above the normal position. Under controlled hemodynamic status, the effect of these THV positions on valve performance (mean TVPG, geometric orifice area, and effective orifice area), thrombotic potential (sinus shear stress), and migration risk (pullout force and embolization flow rate) were assessed.
  
  
  RESULTS
  Compared with normal implantation, a progressive reduction of mean TVPG was observed with each supra-annular THV position (normal: 33.10 mm Hg; 3 mm: 24.69 mm Hg; 6 mm: 19.16 mm Hg; and 8 mm: 12.98 mm Hg; p < 0.001). Simultaneously, we observed increases in geometric orifice area (normal: 0.83 cm(2); 8 mm: 1.60 cm(2); p < 0.001) and effective orifice area (normal: 0.80 cm(2); 8 mm: 1.28 cm(2); p < 0.001) and reductions in sinus shear stresses (normal: 153 dyne/cm(2); 8 mm: 40 dyne/cm(2); p < 0.001), pullout forces (normal: 1.55 N; 8 mm: 0.68 N; p < 0.05), and embolization flow rates (normal: 32.91 l/min; 8 mm: 26.06 l/min; p < 0.01).
  
  
  CONCLUSIONS
  Supra-annular implantation of a THV in a small surgical bioprosthesis reduces mean TVPG but may increase the risk for leaflet thrombosis and valve migration. A 3- to 6-mm supra-annular deployment could be an optimal position in these cases.
authors.affiliation: Georgia Institute of Technology, Atlanta, Georgia.
authors.forename: Prem A
authors.initials: PA
authors.lastname: Midha
authors.affiliation: Georgia Institute of Technology, Atlanta, Georgia.
authors.forename: Vrishank
authors.initials: V
authors.lastname: Raghav
authors.affiliation: Emory University Hospitals, Atlanta, Georgia.
authors.forename: Jose F
authors.initials: JF
authors.lastname: Condado
authors.affiliation: Georgia Institute of Technology, Atlanta, Georgia.
authors.forename: Sivakkumar
authors.initials: S
authors.lastname: Arjunon
authors.affiliation: Georgia Institute of Technology, Atlanta, Georgia.
authors.forename: Domingo E
authors.initials: DE
authors.lastname: Uceda
authors.affiliation: Emory University Hospitals, Atlanta, Georgia.
authors.forename: Stamatios
authors.initials: S
authors.lastname: Lerakis
authors.affiliation: Emory University Hospitals, Atlanta, Georgia.
authors.forename: Vinod H
authors.initials: VH
authors.lastname: Thourani
authors.affiliation: Emory University Hospitals, Atlanta, Georgia.
authors.forename: Vasilis
authors.initials: V
authors.lastname: Babaliaros
authors.affiliation: Georgia Institute of Technology, Atlanta, Georgia. Electronic address: ajit.yoganathan@bme.gatech.edu.
authors.forename: Ajit P
authors.initials: AP
authors.lastname: Yoganathan
mesh_terms: D001021:Aortic Valve / Q000503:physiopathology / Q000601:surgery*; D001705:Bioprosthesis; D006328:Cardiac Catheterization / Q000009:adverse effects / Q000295:instrumentation*; D019544:Equipment Failure Analysis; D006349:Heart Valve Diseases / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery / Q000628:therapy*; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation / Q000009:adverse effects / Q000295:instrumentation*; D006439:Hemodynamics; D006801:Humans; D008422:Materials Testing; D008953:Models, Anatomic; D011474:Prosthesis Design; D011475:Prosthesis Failure; D013927:Thrombosis / Q000209:etiology
keywords: small bioprosthesis; transcatheter aortic valve; valve-in-valve