title: The effect of synthetic patch repair of coarctation on regional deformation of the aortic wall.
abstract: BACKGROUND
  A long-term complication of synthetic patch repair of coarctation is true aneurysm formation.
  
  
  OBJECTIVE
  An in vitro study was undertaken to determine the effects of patch angioplasty on aortic geometry and strain adjacent to the patch.
  
  
  METHODS
  Segments of human descending thoracic aorta were subject to 10 pressure loading cycles (10-120 mm Hg; 1.36-16.32 kPa) before and after simulated coarctation repair with a synthetic patch. Local curvature and strain were estimated by fitting a geometric model to reconstructed three-dimensional surface marker points.
  
  
  RESULTS
  In the control aortas, when pressure increased from 11 +/- 1.0 to 124 +/- 4.0 mm Hg (1.5 +/- 0.14 to 16.86 +/- 0.54 kPa), average circumferential curvature decreased from 0.1543 +/- 0.03 to 0.1065 +/- 0.03 mm(-1). The average major extension reached a maximum of 1.43 +/- 0.08. After patch implantation, the average circumferential curvature was reduced relative to control at all pressures. Average major extensions were significantly greater than paired control values and reached a maximum of 1.55 +/- 0.08 at 122 +/- 4.0 mm Hg (16.59 +/- 0. 54 kPa). Substantial strain inhomogeneity was observed and major extensions were greatest immediately adjacent to the patch.
  
  
  CONCLUSIONS
  Synthetic patch repair of coarctation of the aorta increases wall strain and produces significant regional gradients in strain. With control aortic material properties there may be a substantial increase in wall stress immediately adjacent to the aorta, which could lead to true aneurysm formation.
authors.affiliation: Departments of Physiology and Engineering Science, University of Auckland, Auckland, New Zealand.
authors.forename: B H
authors.initials: BH
authors.lastname: Smaill
authors.forename: D C
authors.initials: DC
authors.lastname: McGiffin
authors.forename: I J
authors.initials: IJ
authors.lastname: Legrice
authors.forename: A A
authors.initials: AA
authors.lastname: Young
authors.forename: P J
authors.initials: PJ
authors.lastname: Hunter
authors.forename: A J
authors.initials: AJ
authors.lastname: Galbraith
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D017545:Aortic Aneurysm, Thoracic / Q000209:etiology*; D001017:Aortic Coarctation / Q000601:surgery*; D015982:Bias; D001807:Blood Vessel Prosthesis / Q000009:adverse effects*; D002648:Child; D005260:Female; D020342:Finite Element Analysis; D018056:Hemorheology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D066298:In Vitro Techniques; D008297:Male; D008955:Models, Cardiovascular; D013314:Stress, Mechanical