title: Annular dilatation and loss of sino-tubular junction in aneurysmatic aorta: implications on leaflet quality at the time of surgery. A finite element study.
abstract: OBJECTIVE
  In the belief that stress is the main determinant of leaflet quality deterioration, we sought to evaluate the effect of annular and/or sino-tubular junction dilatation on leaflet stress. A finite element computer-assisted stress analysis was used to model four different anatomic conditions and analyse the consequent stress pattern on the aortic valve.
  
  
  METHODS
  Theoretical models of four aortic root configurations (normal, with dilated annulus, with loss of sino-tubular junction and with both dilatation simultaneously) were created with computer-aided design technique. The pattern of stress and strain was then analysed by means of finite elements analysis, when a uniform pressure of 100 mmHg was applied to the model. Analysis produced von Mises charts (colour-coded, computational, three-dimensional stress-pattern graphics) and bidimensional plots of compared stress on arc-linear line, which allowed direct comparison of stress in the four different conditions.
  
  
  RESULTS
  Stresses both on the free margin and on the 'belly' of the leaflet rose from 0.28 MPa (normal conditions) to 0.32 MPa (+14%) in case of isolated dilatation of the sino-tubular junction, while increased to 0.42 MPa (+67%) in case of isolated annular dilatation, with no substantial difference whether sino-tubular junction dilatation was present or not.
  
  
  CONCLUSIONS
  Annular dilatation is the key element determining an increased stress on aortic leaflets independently from an associated sino-tubular junction dilatation. The presence of annular dilatation associated with root aneurysm greatly decreases the chance of performing a valve sparing procedure without the need for additional manoeuvres on leaflet tissue. This information may lead to a refinement in the optimal surgical strategy.
authors.affiliation: Department of Cardiac Surgery, European Hospital, Rome, Italy. lweltert@gmail.com
authors.forename: Luca
authors.initials: L
authors.lastname: Weltert
authors.forename: Marco D
authors.initials: MD
authors.lastname: de Tullio
authors.forename: Luciano
authors.initials: L
authors.lastname: Afferrante
authors.forename: Andrea
authors.initials: A
authors.lastname: Salica
authors.forename: Raffaele
authors.initials: R
authors.lastname: Scaffa
authors.forename: Daniele
authors.initials: D
authors.lastname: Maselli
authors.forename: Roberto
authors.initials: R
authors.lastname: Verzicco
authors.forename: Ruggero
authors.initials: R
authors.lastname: De Paulis
mesh_terms: D001011:Aorta / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery; D001014:Aortic Aneurysm / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery; D001021:Aortic Valve / Q000473:pathology / Q000503:physiopathology*; D003198:Computer Simulation; D004108:Dilatation, Pathologic; D020342:Finite Element Analysis; D006439:Hemodynamics; D006801:Humans; D008953:Models, Anatomic; D008955:Models, Cardiovascular; D013314:Stress, Mechanical
keywords: Aneurysm; Annular dilatation; Aorta; Finite element
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