title: Right ventricular papillary muscle approximation as a novel technique of valve repair for functional tricuspid regurgitation in an ex vivo porcine model.
abstract: OBJECTIVE
  Annuloplasty for functional tricuspid regurgitation may sometimes be ineffective because of chamber dilation and valve tethering. This study compared a novel technique, right ventricle (RV)-papillary muscle approximation, with annuloplasty in experimentally-produced tricuspid regurgitation.
  
  
  METHODS
  RVs of isolated porcine hearts (n = 10) were statically pressurized, which led to RV dilation and central tricuspid regurgitation. Regurgitant flow was measured with a saline solution-filled column. The head of the anterior papillary muscle was approximated to 4 points on the ventricular septum. Next, a prosthetic ring was implanted, and then RV-papillary muscle approximation was combined. Tricuspid annular dimension, RV geometry, and tricuspid valve tethering were analyzed with 3-dimensional echocardiography.
  
  
  RESULTS
  Tricuspid regurgitation (2270 ± 186 mL/min) was reduced by RV-papillary muscle approximation alone (214 ± 45 mL/min; P < .05) more than by annuloplasty alone (724 ± 166 mL/min; P < .05). Combined RV-papillary muscle approximation and annuloplasty resulted in the least regurgitation (80 ± 39 mL/min). RV-papillary muscle approximation reduced tricuspid septolateral diameter (25%; P < .05), and annular area (23%; P < .05), as did annuloplasty. RV-papillary muscle approximation also reduced RV sphericity index (33%; P < .05) and tricuspid tethering height (54%; P < .05), whereas annuloplasty did not. Direction of RV-papillary muscle approximation did not independently affect outcomes.
  
  
  CONCLUSIONS
  This ex vivo study suggests that RV-papillary muscle approximation potentially repairs tricuspid regurgitation better than annuloplasty by improving ventricular sphericity and valve tethering as well as annular dimension.
authors.affiliation: Department of Cardiac Surgery, Children's Hospital Boston, Harvard Medical School, Boston, Mass., USA.
authors.forename: Haruo
authors.initials: H
authors.lastname: Yamauchi
authors.forename: Nikolay V
authors.initials: NV
authors.lastname: Vasilyev
authors.forename: Gerald R
authors.initials: GR
authors.lastname: Marx
authors.forename: Hugo
authors.initials: H
authors.lastname: Loyola
authors.forename: Muralidhar
authors.initials: M
authors.lastname: Padala
authors.forename: Ajit P
authors.initials: AP
authors.lastname: Yoganathan
authors.forename: Pedro J
authors.initials: PJ
authors.lastname: del Nido
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D019560:Echocardiography, Three-Dimensional; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D066298:In Vitro Techniques; D023421:Models, Animal; D010210:Papillary Muscles / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D013552:Swine; D014262:Tricuspid Valve Insufficiency / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*