title: Off-pump mitral valved stent implantation: comparison of apical and subannular fixation techniques.
abstract: OBJECTIVE
  A large cohort of patients suffering from severe mitral regurgitation does not meet the indications for conventional surgery and would greatly benefit from a transcatheter approach in the beating heart. Consequently, off-pump transcatheter mitral valve procedures have been the focus of recent research. The aim of this study was the in vivo evaluation and comparison of subannular versus apical fixation of mitral valved stents to show the feasibility of subannular anchorage.
  
  
  METHODS
  Twenty-two pigs received a self-expanding valved stent in the mitral position in an off-pump procedure. The first design (design AP: n = 12) was anchored apically and served as the control group. The second design (design SA: n = 10) included additional sub-annular fixation elements. Echocardiographic and haemodynamic evaluations were conducted before and 1 h after stent implantation.
  
  
  RESULTS
  Haemodynamic stability was achieved, and the capillary wedge pressure was within a normal range (AP: 11 ± 4 mmHg, SA: 9 ± 4 mmHg). Paravalvular leakages were trace or less in 19 of 20 cases. The mean gradients across the valved stent increased (P ≤ 0.014) but remained within a physiological range in both groups (AP: 1.2 ± 0.6 mmHg, SA: 2.6 ± 2.0 mmHg). The longitudinal heart function remained within a physiological normal range (AP: 0.95 ± 0.1 cm, SA: 0.95 ± 0.1 cm) but was reduced in group SA. The ejection fraction decreased after stent implantation (AP: 52 ± 10%, SA: 48 ± 4%). The mean survival time was higher in group AP compared with group SA.
  
  
  CONCLUSIONS
  The proof-of-principle for the subannular fixation was shown with haemodynamic stability, low gradients and physiological longitudinal function. A decreased ejection fraction, survival time and fractures identify potential areas for improvement. With regard to the long-term outcome, the group with subannular fixation did not reach the results of the group with apical fixation in this study.
authors.affiliation: Department of Cardiovascular Surgery, Christian-Albrechts-University of Kiel, School of Medicine, Kiel, Germany saskia.pokorny@uksh.de.|Institute of Biomechanics, TUHH Hamburg University of Technology, Hamburg, Germany.
authors.forename: Saskia
authors.initials: S
authors.lastname: Pokorny
authors.affiliation: Department of Cardiovascular Surgery, Christian-Albrechts-University of Kiel, School of Medicine, Kiel, Germany.
authors.forename: Katharina
authors.initials: K
authors.lastname: Huenges
authors.affiliation: Department of Pediatric Cardiology, Christian-Albrechts-University of Kiel, School of Medicine, Kiel, Germany.
authors.forename: Jan Hinerk
authors.initials: JH
authors.lastname: Hansen
authors.affiliation: Department of Cardiovascular Surgery, Christian-Albrechts-University of Kiel, School of Medicine, Kiel, Germany.
authors.forename: Yannik
authors.initials: Y
authors.lastname: Schadow
authors.affiliation: Department of Pediatric Cardiology, Christian-Albrechts-University of Kiel, School of Medicine, Kiel, Germany.
authors.forename: Gunther
authors.initials: G
authors.lastname: Fischer
authors.affiliation: Institute of Biomechanics, TUHH Hamburg University of Technology, Hamburg, Germany.
authors.forename: Michael M
authors.initials: MM
authors.lastname: Morlock
authors.affiliation: Department of Cardiovascular Surgery, Christian-Albrechts-University of Kiel, School of Medicine, Kiel, Germany.
authors.forename: Jochen
authors.initials: J
authors.lastname: Cremer
authors.affiliation: Department of Cardiovascular Surgery, Christian-Albrechts-University of Kiel, School of Medicine, Kiel, Germany.
authors.forename: Georg
authors.initials: G
authors.lastname: Lutter
mesh_terms: D000818:Animals; D006328:Cardiac Catheterization / Q000379:methods*; D004195:Disease Models, Animal; D017548:Echocardiography, Transesophageal; D005240:Feasibility Studies; D005260:Female; D019918:Heart Valve Prosthesis Implantation / Q000379:methods*; D008943:Mitral Valve / Q000000981:diagnostic imaging / Q000601:surgery*; D008944:Mitral Valve Insufficiency / Q000175:diagnosis / Q000601:surgery*; D011474:Prosthesis Design; D015607:Stents; D013536:Suture Techniques; D013552:Swine
keywords: Fixation techniques; Mitral valved stent; Off-pump; Stent design; Transapical; Transcatheter