title: CT-reconstructed three-dimensional printed models of the right subclavian artery and aorta define age-related changes and facilitate benchtop catheter testing.
abstract: BACKGROUND
  Severe tortuosity of the right subclavian artery (RSCA) encountered during transradial cardiac catheterization can lead to longer procedures, increased fluoroscopy time, inability to engage the coronary artery ostia, and potentially procedural failure. Increasing age is strongly correlated with subclavian tortuosity; however, the magnitude and direction of age-related changes in aortic and subclavian artery anatomy have not been defined.
  
  
  METHODS
  Chest computed tomography (CT) angiograms of 14 patients (6 age <45 years and 8 age ≥75 years) were evaluated for RSCA tortuosity. Measurements were taken along the midline of the vessel and compared to the straight distance traveled (index of tortuosity = straight distance/midline length). One normal and one tortuous subclavian were selected for three-dimensional printing and various catheters were benchtop tested on both models.
  
  
  RESULTS
  The older group had longer (11.95 cm vs 9.6 cm; P<.01) and more tortuous subclavian arteries (lower index of tortuosity, 0.65 vs 0.76; P<.01) with more posterior unfolding (distance to most posterior aspect, 3.74 ± 0.77 cm vs 1.76 ± 0.58 cm; P<.001). Engagement of the coronary arteries of the normal model was significantly easier, with successful engagement of one or both coronaries with every catheter (n=7). Only 2 of 7 catheters (Radial Brachial and Extra Backup 3.0) were able to engage the coronary arteries in the tortuous model.
  
  
  CONCLUSIONS
  Age is associated with elongation, tortuosity, and posterior unfolding of the RSCA. Three-dimensional printing of normal and tortuous arteries is feasible and shows potential to test differences between catheters.
authors.affiliation: University of Newcastle Department of Medicine, Division of Cardiology, John Hunter Hospital, Lookout Rd, New Lambton Heights, Newcastle, NSW 2905, Australia. andrewboyle500@gmail.com.
authors.forename: Erik
authors.initials: E
authors.lastname: Velez
authors.forename: Nathan
authors.initials: N
authors.lastname: Boyer
authors.forename: Gabriel
authors.initials: G
authors.lastname: Acevedo-Bolton
authors.forename: Michael D
authors.initials: MD
authors.lastname: Hope
authors.forename: Andrew
authors.initials: A
authors.lastname: Boyle
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D000792:Angiography / Q000379:methods*; D001011:Aorta / Q000473:pathology*; D006328:Cardiac Catheterization / Q000379:methods*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008875:Middle Aged; D008955:Models, Cardiovascular; D066330:Printing, Three-Dimensional; D013348:Subclavian Artery / Q000473:pathology*; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome