title: The dissected aorta: part I. Early anatomic changes in an in vitro model.
abstract: OBJECTIVE
  To define early anatomic changes in the aorta in an in vitro hydrostatic model of acute aortic dissection.
  
  
  METHODS
  Aortic dissections were created in explanted aortas. A small portion of the dissection flap was resected to allow free communication between the true and false lumina. The aortas were suspended in a saline bath and distended by means of a saline fluid column. By using intravascular ultrasonography, the arc lengths of the outer walls of the true and false lumina and of the dissection flap were measured at increasing hydrostatic pressures and at increasing fractions of dissected wall circumference.
  
  
  RESULTS
  The dissected aorta immediately became ectatic. At a given fraction of wall circumference involved in dissection, total aortic cross-sectional area increased with increased hydrostatic pressure. At a given hydrostatic pressure, this area increased with increased fraction of wall circumference dissected. Most of the increase was due to dilatation of the false lumen. There were minimal changes in true-lumen size. Dissection flap length, after initial contraction at the time of dissection, changed minimally with increasing pressure.
  
  
  CONCLUSIONS
  Anatomic changes in the dissected aorta depend on hydrostatic pressure and on the percentage of aortic wall involved in the dissection.
authors.affiliation: Department of Radiology, University of Michigan, Ann Arbor 48109-0030, USA.
authors.forename: D M
authors.initials: DM
authors.lastname: Williams
authors.forename: M A
authors.initials: MA
authors.lastname: LePage
authors.forename: D Y
authors.initials: DY
authors.lastname: Lee
mesh_terms: D000208:Acute Disease; D000784:Aortic Dissection / Q000000981:diagnostic imaging* / Q000503:physiopathology; D000818:Animals; D001011:Aorta / Q000000981:diagnostic imaging; D001014:Aortic Aneurysm / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006801:Humans; D006874:Hydrostatic Pressure; D066298:In Vitro Techniques; D013552:Swine; D018084:Ultrasonography, Interventional