title: Guidewire stiffness: what's in a name?
abstract: OBJECTIVE
  To measure the stiffness of commonly used "stiff" guidewires in terms of their flexural modulus, an engineering parameter related to bending stiffness.
  
  
  METHODS
  Eleven different intact stiff guidewires were selected to undergo a 3-point bending test performed using a tensile testing machine. Testing was performed on 3 new and intact specimens of each guidewire at 10 locations along the wire's length, excluding the floppy tip. The flexural modulus (in gigapascals, GPa) was calculated from the results of the bending test.
  
  
  RESULTS
  The flexural modulus of the plain Amplatz wire was 9.5 GPa compared to 11.4 to 14.5 GPa for the "heavy duty" wires. Within the Amplatz family of guidewires, the flexural modulus was 17 GPa for the "stiff," 29.2 GPa for the "extra stiff," 60.3 GPa for the "super stiff," and 65.4 GPa for the "ultra stiff." The Backup Meier measured 139.6 GPa and the Lunderquist Extra Stiff 158.4 GPa.
  
  
  CONCLUSIONS
  The Instructions for Use of some endovascular devices specify a wire type selected from a range of undefined "stiffness" descriptors. These descriptors have little correlation with the measured flexural modulus. Two guidewires with the description "extra stiff" can have a 5-fold difference in flexural modulus. We recommend that guidewire catalogues and packaging include the flexural modulus and that device manufacturers amend their Instructions for Use accordingly.
authors.affiliation: Regional Vascular Unit, Royal Liverpool University Hospital, Liverpool, UK. garethjamesharrison@yahoo.co.uk
authors.forename: Gareth J
authors.initials: GJ
authors.lastname: Harrison
authors.forename: Thien V
authors.initials: TV
authors.lastname: How
authors.forename: S Rao
authors.initials: SR
authors.lastname: Vallabhaneni
authors.forename: John A
authors.initials: JA
authors.lastname: Brennan
authors.forename: Robert K
authors.initials: RK
authors.lastname: Fisher
authors.forename: Jagjeeth B
authors.initials: JB
authors.lastname: Naik
authors.forename: Richard G
authors.initials: RG
authors.lastname: McWilliams
mesh_terms: D001807:Blood Vessel Prosthesis; D057510:Endovascular Procedures / Q000295:instrumentation*; D008422:Materials Testing; D018583:Pliability