title: Intracardiac ultrasonic suture welding for knotless mitral valve replacement.
abstract: OBJECTIVE
  The difficulty in tying multiple knots with endoscopic instruments constitutes a technical obstacle to the development of closed-chest valve surgery. The following set of experiments was undertaken to ascertain the in-vivo feasibility of using an intracardiac ultrasonic welding device for knotless suture fixation during mitral valve replacement (MVR).
  
  
  METHODS
  Five adult sheep weighing 48-52 kg underwent MVR with a commercially available mechanical prosthesis, using pledgetted interrupted polypropylene sutures. An ultrasonic suture welder designed for intracardiac use was used to adjust suture tension and fuse strands together without knots. Echocardiographic assessment of the mitral prosthesis was carried out at baseline and after maintenance of supraphysiologic arterial pressures for 60 min. Subsequently, the animals' explanted hearts were assessed under sustained left ventricular (LV) pressurization to 180 mmHg in an ex-vivo pressure-loop system.
  
  
  RESULTS
  MVR was successfully performed in all animals and welds reliably completed in less than 1 s. One sheep could not successfully be weaned off cardiopulmonary bypass; however, a normal prosthetic valve implant was confirmed at post-mortem examination. Echocardiographic assessment prior to and during LV pressurization revealed normal seating and function of the prosthesis in all cases. At post-mortem examination all valves were adequately implanted, suture tails laid flat on the surface of the prosthesis' sewing ring, welded suture strands were intact and accurately point-fused together, and no evidence of perivalvular leak was found around any of the prostheses despite sustained LV pressurization.
  
  
  CONCLUSIONS
  This new modality proved reliable in an acute sheep model of MVR and could constitute a promising avenue towards facilitation of total endoscopic valve procedures in humans.
authors.affiliation: Division of Cardiothoracic Surgery, Beth Israel Deaconess Medical Center, LMOB 2A, 110 Francis Street, Boston, MA 02215, USA.
authors.forename: Marc
authors.initials: M
authors.lastname: Ruel
authors.forename: Richard B
authors.initials: RB
authors.lastname: Streeter
authors.forename: Ralph
authors.initials: R
authors.lastname: de la Torre
authors.forename: John R
authors.initials: JR
authors.lastname: Liddicoat
authors.forename: William E
authors.initials: WE
authors.lastname: Cohn
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D005260:Female; D006350:Heart Valve Prosthesis; D008297:Male; D019060:Minimally Invasive Surgical Procedures / Q000379:methods; D008943:Mitral Valve / Q000601:surgery*; D012680:Sensitivity and Specificity; D012756:Sheep; D013536:Suture Techniques; D013718:Tensile Strength