title: Off-pump replacement of the pulmonary valve in large right ventricular outflow tracts: a hybrid approach.
abstract: BACKGROUND
  Percutaneous pulmonary valve replacement has recently been introduced and is under investigation in humans. This technique is, however, limited to patients with a right ventricular outflow tract that does not exceed 22 mm in diameter. We report our experience of off-pump pulmonary valve replacement using a hybrid approach in animals with large right ventricular outflow tracts.
  
  
  METHODS
  Eight ewes were included in the protocol and were equally divided into 2 groups. A left thoracotomy was first performed, and the main pulmonary artery was banded by using 2 radiopaque rings with a diameter of 18 mm that allowed for further pulmonary valve replacement. We then intended to implant a valved stent either percutaneously (group 1) or through a transventricular approach (group 2). All animals were killed after valve implantation. The operation allowed the pulmonary diameter to be reduced from 30 to 17.6 mm.
  
  
  RESULTS
  The right ventricular pressure did not significantly increase after reduction of the pulmonary artery diameter (25 vs 36 mm Hg). Subsequent pulmonary valve replacement through a percutaneous or a transventricular approach was always possible without any requirement for extracorporeal circulation. All devices were successfully delivered inside the pulmonary artery banding and were functioning perfectly at early evaluation.
  
  
  CONCLUSIONS
  Implantation of a pulmonary valve is possible in ewes through a hybrid approach when the right ventricular outflow tract exceeds 22 mm in diameter. This involves both surgeons and interventionists and allows for a staged procedure in which the valvulation is performed percutaneously or, for a combined hybrid approach, in which the valve is implanted off pump transventricularly during the same operation.
authors.affiliation: Service de Cardiologie pédiatrique, Hôpital Necker Enfants Malades, Paris, France. younes.boudjemline@nck.ap-hop-paris.fr
authors.forename: Younes
authors.initials: Y
authors.lastname: Boudjemline
authors.forename: Silvia
authors.initials: S
authors.lastname: Schievano
authors.forename: Caroline
authors.initials: C
authors.lastname: Bonnet
authors.forename: Louise
authors.initials: L
authors.lastname: Coats
authors.forename: Gabriella
authors.initials: G
authors.lastname: Agnoletti
authors.forename: Sachin
authors.initials: S
authors.lastname: Khambadkone
authors.forename: Damien
authors.initials: D
authors.lastname: Bonnet
authors.forename: John
authors.initials: J
authors.lastname: Deanfield
authors.forename: Daniel
authors.initials: D
authors.lastname: Sidi
authors.forename: Philipp
authors.initials: P
authors.lastname: Bonhoeffer
mesh_terms: D000818:Animals; D006328:Cardiac Catheterization; D002404:Catheterization / Q000295:instrumentation; D005260:Female; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation / Q000295:instrumentation / Q000379:methods*; D006352:Heart Ventricles / Q000601:surgery*; D011651:Pulmonary Artery / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D011664:Pulmonary Valve / Q000601:surgery*; D011859:Radiography; D012756:Sheep; D015607:Stents; D013908:Thoracotomy; D017725:Ventricular Pressure / Q000502:physiology