title: The impact of aging on the course of the azygos vein.
abstract: BACKGROUND
  The human azygos vein (AV) generally runs on the right side of the vertebral column. However, a shift in its course to the middle/left side of the vertebral column, potentially as a result of aging, has been reported. The aim of this study was to understand the relationship between AV displacement and aging.
  
  
  METHODS
  Forty-seven adult cadavers were dissected. When an AV left shift was observed, long axis AV length was measured by calculating the number of vertebral bodies under the vein. We also investigated whether a crossover vein existed between AV and hemiazygos vein at the extreme left shifting point, and whether osteophytes existed along the vertebral column.
  
  
  RESULTS
  Forty-four cadavers (94%) had left-shifted AVs. A weak positive correlation between age and the length of the left shift was observed (r = 0.3061, P = 0.0364). Thirty cadavers (64%) had crossover veins at the extreme left shifting point, and 24 cadavers (51%) had osteophytes along the vertebral column. There was no significant relationship between the length of left-shifted AVs and the existence of crossover veins or osteophytes.
  
  
  CONCLUSIONS
  The possibility of AV displacement to the left as part of the aging process is suggested.
authors.affiliation: Department of Anatomy, Showa University School of Medicine.
authors.forename: Akira
authors.initials: A
authors.lastname: Saito
authors.forename: Masahiko
authors.initials: M
authors.lastname: Murakami
authors.forename: Kodai
authors.initials: K
authors.lastname: Tomioka
authors.forename: Hiromitsu
authors.initials: H
authors.lastname: Ezure
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Moriyama
authors.forename: Ryoichi
authors.initials: R
authors.lastname: Mori
authors.forename: Koh
authors.initials: K
authors.lastname: Nakajima
authors.forename: Masanori
authors.initials: M
authors.lastname: Nakamura
authors.forename: Naruhito
authors.initials: N
authors.lastname: Otsuka
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D001401:Azygos Vein / Q000033:anatomy & histology*; D002102:Cadaver; D005260:Female; D006801:Humans; D008297:Male; D008953:Models, Anatomic; D013131:Spine / Q000098:blood supply*