title: Acute mitral valve regurgitation created in sheep using echocardiographic guidance.
abstract: OBJECTIVE
  This study was designed to determine: (i) Whether acute mitral valve regurgitation (MVR) due to chordal rupture can be reproducibly created under echocardiographic guidance; (ii) what degree of MVR can be created; (iii) what degree of acute regurgitation is survivable; and (iv) whether acute MVR due to chordal rupture progresses over time.
  
  
  METHODS
  In a pilot group of six juvenile farm-bred sheep, selected chordae tendineae were ruptured using either a biopsy needle or endoscopic scissors under echocardiographic guidance, without need for cardiopulmonary bypass. Sheep were sacrificed acutely (n = 2), and at six weeks (n = 2) or eight weeks (n = 2). When the technique was optimized, five sheep entered a study group in which chords were ruptured using endoscopic scissors; the sheep were sacrificed 16 weeks after surgery.
  
  
  RESULTS
  In the pilot study, acute MVR (grade 2-4+) was produced in all sheep, normal ventricular wall motion was maintained, with minimal progression of regurgitation over time. In one pilot sheep which did not survive, grade 4+ MVR was created acutely. Use of endoscopic scissors was preferable to the biopsy needle. In the study group, acute MVR (grade 2-4+) was produced in all five sheep, and was still present at 16 weeks, with progression in only one animal.
  
  
  CONCLUSIONS
  This pilot study demonstrated that controlled degrees of survivable acute MVR due to chordal rupture can be created under echocardiographic guidance, with minimal progression of MVR over time. This animal model can be applied to investigate the pathogenesis of clinical MVR, and to suggest appropriate medical or surgical intervention.
authors.affiliation: Division of Cardiothoracic Surgery, University of Washington, Seattle, USA.
authors.forename: K S
authors.initials: KS
authors.lastname: Kunzelman
authors.forename: D T
authors.initials: DT
authors.lastname: Linker
authors.forename: S
authors.initials: S
authors.lastname: Sai
authors.forename: C
authors.initials: C
authors.lastname: Miyake-Hull
authors.forename: D
authors.initials: D
authors.lastname: Quick
authors.forename: R
authors.initials: R
authors.lastname: Thomas
authors.forename: C
authors.initials: C
authors.lastname: Rothnie
authors.forename: R P
authors.initials: RP
authors.lastname: Cochran
mesh_terms: D000208:Acute Disease; D000818:Animals; D006348:Cardiac Surgical Procedures / Q000295:instrumentation*; D002815:Chordae Tendineae / Q000000981:diagnostic imaging / Q000293:injuries* / Q000473:pathology; D004195:Disease Models, Animal; D004452:Echocardiography; D015150:Echocardiography, Doppler; D004724:Endoscopy; D008943:Mitral Valve / Q000000981:diagnostic imaging / Q000293:injuries* / Q000473:pathology; D008944:Mitral Valve Insufficiency / Q000000981:diagnostic imaging / Q000209:etiology* / Q000503:physiopathology; D009200:Myocardial Contraction; D010865:Pilot Projects; D012421:Rupture; D012756:Sheep