title: Expanded Polytetrafluoroethylene for Chordal Replacement: Preventing Knot Failure.
abstract: OBJECTIVE
  Expanded polytetrafluoroethylene suture is commonly used for chordal replacement in mitral valve repair, but due to material characteristics, knots can unravel. Our aim was to determine the knot security, including how many throws are necessary to prevent knot failure, with Gore-Tex (W.L. Gore and Associates, Elkton, MD) and the newly available Chord-X (On-X Life Technologies Inc, Austin, TX).
  
  
  METHODS
  Knots were evaluated for maximal load based on: number of throws (6, 8, 10, and 12), tension to secure each throw (10%, 50%, and 85%) and suture type (Gore-Tex CV-5 and Chord-X 3-0). A physiologic force of 2 N was used for comparison.
  
  
  RESULTS
  We evaluated 240 knots. For all knots, the mean load to failure was 11.1 ± 5.8 N. Failure occurred due to unraveling in 141 knots (59%) at 7.1 ± 4.1 N and to breaking in 99 (41%) at 16.7 ± 2.0 N (p < 0.01). Gore-Tex failed at higher loads (12.6 ± 6.0 N vs 9.5 ± 5.2 N, p < 0.01); however, an equivalent number, 6 Gore-Tex and 6 Chord-X, unraveled at 2 N, all with fewer than 10 throws.
  
  
  CONCLUSIONS
  Expanded polytetrafluoroethylene has adequate strength to prevent breakage; however, a risk of knot unraveling at physiologic conditions exists when fewer than 10 throws are performed.
authors.affiliation: Washington University in St. Louis School of Medicine and Department of Cardiothoracic Surgery, Barnes-Jewish Hospital, St. Louis, Missouri.
authors.forename: Jacob R
authors.initials: JR
authors.lastname: Miller
authors.affiliation: Washington University in St. Louis School of Medicine and Department of Cardiothoracic Surgery, Barnes-Jewish Hospital, St. Louis, Missouri.
authors.forename: Corey R
authors.initials: CR
authors.lastname: Deeken
authors.affiliation: Washington University in St. Louis School of Medicine and Department of Cardiothoracic Surgery, Barnes-Jewish Hospital, St. Louis, Missouri.
authors.forename: Shuddhadeb
authors.initials: S
authors.lastname: Ray
authors.affiliation: Washington University in St. Louis School of Medicine and Department of Cardiothoracic Surgery, Barnes-Jewish Hospital, St. Louis, Missouri.
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Henn
authors.affiliation: Washington University in St. Louis School of Medicine and Department of Cardiothoracic Surgery, Barnes-Jewish Hospital, St. Louis, Missouri.
authors.forename: Timothy S
authors.initials: TS
authors.lastname: Lancaster
authors.affiliation: Washington University in St. Louis School of Medicine and Department of Cardiothoracic Surgery, Barnes-Jewish Hospital, St. Louis, Missouri.
authors.forename: Richard B
authors.initials: RB
authors.lastname: Schuessler
authors.affiliation: Washington University in St. Louis School of Medicine and Department of Cardiothoracic Surgery, Barnes-Jewish Hospital, St. Louis, Missouri.
authors.forename: Ralph J
authors.initials: RJ
authors.lastname: Damiano
authors.affiliation: Washington University in St. Louis School of Medicine and Department of Cardiothoracic Surgery, Barnes-Jewish Hospital, St. Louis, Missouri. Electronic address: melbys@wudosis.wustl.edu.
authors.forename: Spencer J
authors.initials: SJ
authors.lastname: Melby
mesh_terms: D004868:Equipment Failure; D019918:Heart Valve Prosthesis Implantation / Q000379:methods*; D006801:Humans; D008422:Materials Testing; D008943:Mitral Valve / Q000601:surgery*; D008954:Models, Biological; D011138:Polytetrafluoroethylene; D011183:Postoperative Complications / Q000517:prevention & control*; D013536:Suture Techniques / Q000295:instrumentation*; D013537:Sutures / Q000592:standards*; D013718:Tensile Strength
chemical_list: D011138:Polytetrafluoroethylene