title: Distal-tip shape-consistency testing of steam-shaped microcatheters suitable for cerebral aneurysm coil placement.
abstract: OBJECTIVE
  Although the selection of microcatheter for endovascular aneurysmal treatment is one important factor in patient outcome, the use of steam shaping for achieving safe entry and stability during coil placement has not, to our knowledge, been systematically evaluated. The goal of this study was to compare the durability of distal microcatheter steam shaping in five different catheters with typical intraprocedural stresses that are similar to those encountered during aneurysm coil placement.
  
  
  METHODS
  Distal tips of microcatheters were shaped into a 90 degrees turn with distal straight-segment lengths of 3, 5, or 7 mm by using steam, performed according to the instructions for use included with each catheter. In a water bath kept at body temperature, the changes in catheter tip angle were recorded and measured following microcatheter insertion into a guiding catheter, microguidewire insertion through the microcatheter, and Guglielmi detachable coil (GDC) placement through the microcatheter.
  
  
  RESULTS
  The degree of distal microcatheter straightening with typical intraprocedural manipulations was more pronounced on braided microcatheters and on microcatheters with 3- or 5-mm distal-shaped segments. The degree of spontaneous recovery of the initially steamed shape was more pronounced with nonbraided catheters. The most significant single variable contributing to straightening of a steam-shaped catheter tip was the effect of microguidewire insertion. The catheter-tip straightening effect encountered with inserting GDCs was less than that encountered with microguidewire insertion. We demonstrated that the decreased catheter-tip angle encountered with a large-magnitude straightening stress spontaneously recovered once the stress was removed or when it was reduced to a smaller magnitude stress.
  
  
  CONCLUSIONS
  Our study shows that, although braided microcatheters are suitable for maintaining durable configurations when long distal-tip lengths are permissible, nonbraided microcatheters demonstrate the most durable distal-tip configurations when short distal-tip lengths are called for. This may be one of significant factors in catheter choice for endovascular treatment of aneurysm.
authors.affiliation: Department of Radiology, Kurume University School of Medicine, Fukuoka, Japan.
authors.forename: Toshi
authors.initials: T
authors.lastname: Abe
authors.forename: Masaru
authors.initials: M
authors.lastname: Hirohata
authors.forename: Norimitsu
authors.initials: N
authors.lastname: Tanaka
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Uchiyama
authors.forename: Kiminori
authors.initials: K
authors.lastname: Fujimoto
authors.forename: Naoko
authors.initials: N
authors.lastname: Fujimura
authors.forename: Alexander M
authors.initials: AM
authors.lastname: Norbash
authors.forename: Naofumi
authors.initials: N
authors.lastname: Hayabuchi
mesh_terms: D002404:Catheterization / Q000295:instrumentation*; D004867:Equipment Design; D002532:Intracranial Aneurysm / Q000628:therapy*; D008904:Miniaturization; D013314:Stress, Mechanical