title: The non-circular shape of FloWatch-PAB prevents the need for pulmonary artery reconstruction after banding. Computational fluid dynamics and clinical correlations.
abstract: OBJECTIVE
  To evaluate the differences between non-circular shape of FloWatch-PAB and conventional pulmonary artery (PA) banding.
  
  
  METHODS
  Geometrical analysis. Conventional banding and FloWatch-PAB perimeters were plotted against cross-sections. Computational fluid dynamics (CFD) model. CFD compared non-circular FloWatch-PAB cross-sections with conventional banding regarding pressure gradients. Clinical data. Seven children, median age 2 months (7 days to 3 years), median weight 4.2 kg (3.2-9.8 kg), with complex congenital heart defects underwent PA banding with FloWatch-PAB implantation.
  
  
  RESULTS
  Geometrical analysis. Conventional banding: progressive reduction of cross-sections was accompanied by progressive reduction of PA perimeters. FloWatch-PAB: with equal reduction of cross-sections the PA perimeter remained constant. CFD model. Non-circular and circular banding provided same trans-banding pressure gradients for same cross-sections at any given flow. Clinical data. Mean PA internal diameter at banding was 13.3+/-4.5 mm. After a mean interval of 5.9+/-3.7 months, all children underwent intra-cardiac repair and simple FloWatch-PAB removal without PA reconstruction. Mean PA internal diameter with FloWatch-PAB removal increased from 3.0+/-0.8 to 12.4+/-4.5 mm (normal mean internal diameter for the age=9.9+/-1.6). No residual pressure gradient was recorded in correspondence of the site of the previous FloWatch-PAB implantation in 6/7 patients, 10 mmHg peak and 5 mmHg mean gradient in 1/7.
  
  
  CONCLUSIONS
  The non-circular shape of FloWatch-PAB can replace conventional circular banding with the following advantages: (a) the pressure gradient will remain essentially the same as for conventional circular banding for any given cross-section, but with significantly smaller reduction of PA perimeter; and (b) PA reconstruction at the time of de-banding for intra-cardiac repair can be avoided.
authors.affiliation: Alder Hey Royal Children Hospital, Eaton Road, Liverpool, L12 2AP, England, UK. Antonio.Corno@rlc.nhs.uk
authors.forename: Antonio F
authors.initials: AF
authors.lastname: Corno
authors.forename: Martin
authors.initials: M
authors.lastname: Prosi
authors.forename: Pierre
authors.initials: P
authors.lastname: Fridez
authors.forename: Paolo
authors.initials: P
authors.lastname: Zunino
authors.forename: Alfio
authors.initials: A
authors.lastname: Quarteroni
authors.forename: Ludwig K
authors.initials: LK
authors.lastname: von Segesser
mesh_terms: D001807:Blood Vessel Prosthesis; D006348:Cardiac Surgical Procedures / Q000295:instrumentation; D002675:Child, Preschool; D003198:Computer Simulation; D003326:Coronary Circulation / Q000502:physiology; D018618:Echocardiography, Doppler, Color / Q000379:methods; D017548:Echocardiography, Transesophageal / Q000379:methods; D006330:Heart Defects, Congenital / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008955:Models, Cardiovascular; D011474:Prosthesis Design; D011651:Pulmonary Artery / Q000503:physiopathology / Q000601:surgery*