title: Off-label use of stretchable polytetrafluoroethylene: overexpansion of synthetic shunts.
abstract: OBJECTIVE
  To describe our experience with balloon dilatation and stenting of modified systemic-to-pulmonary artery (PA) shunts in relation to an assessment and interpretation of the mechanical properties of thin-walled expandable polytetrafluoroethylene (ePTFE) stretch vascular grafts.
  
  
  METHODS
  Our pediatric cardiology/cardiac surgery database was reviewed to identify all infants and children with a modified systemic-to-PA shunt who underwent cardiac catheterization. Reports and images were reviewed. Thin-walled stretchable and regular Gore-Tex vascular grafts were mechanically compared using tensiometry.
  
  
  RESULTS
  11 patients underwent dilatation or stenting procedures of a systemic-to-PA shunt. No major complications occurred and none of our patients died during or due to this intervention. High pressures in balloons and stents with diameters larger than the graft were used. Shunt diameters and oxygen saturation levels increased from 2.05 +/- 1.25 mm to 4.75 +/- 0.88 mm and with 12 +/- 6.8%, respectively. In 6 patients re-catheterizations were performed. Four patients died, all with patent shunts. The fail-stress and the fail-strain in the circumferential direction of the stretchable graft were significantly higher than in the non-stretchable graft.
  
  
  CONCLUSIONS
  Dilatation and stenting of stenosed modified systemic-to-PA shunts is feasible and safe. Dilatation and stenting of these shunts to calibers larger than those provided by the manufacturer is possible. Results of our technical study posit a great advantage for the use of the thin-walled stretch configuration of ePTFE.
authors.affiliation: Department of Surgery, University Hospital Gasthuisberg, Leuven, Belgium. tom.verbelen@student.kuleuven.be
authors.forename: Tom O
authors.initials: TO
authors.lastname: Verbelen
authors.forename: Nele
authors.initials: N
authors.lastname: Famaey
authors.forename: Marc
authors.initials: M
authors.lastname: Gewillig
authors.forename: Filip R
authors.initials: FR
authors.lastname: Rega
authors.forename: Bart
authors.initials: B
authors.lastname: Meyns
mesh_terms: D001807:Blood Vessel Prosthesis; D019917:Blood Vessel Prosthesis Implantation / Q000009:adverse effects / Q000295:instrumentation* / Q000401:mortality; D002404:Catheterization / Q000009:adverse effects / Q000295:instrumentation* / Q000401:mortality; D002675:Child, Preschool; D003251:Constriction, Pathologic; D017023:Coronary Angiography; D018795:Device Approval; D055119:Elastic Modulus; D005260:Female; D006083:Graft Occlusion, Vascular / Q000000981:diagnostic imaging / Q000209:etiology / Q000401:mortality / Q000503:physiopathology / Q000628:therapy*; D006330:Heart Defects, Congenital / Q000401:mortality / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D011138:Polytetrafluoroethylene; D011312:Pressure; D011474:Prosthesis Design; D011651:Pulmonary Artery / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D012189:Retrospective Studies; D015607:Stents; D013997:Time Factors; D016896:Treatment Outcome; D014654:Vascular Patency
chemical_list: D011138:Polytetrafluoroethylene