title: Aortic root haemodynamics following David procedure: numerical analysis of 3-dimensional haemodynamics.
abstract: OBJECTIVE
  The aim was to determine 3-dimensional (3D) geometrical deformation of the aortic root (AoR) following the David procedure in order to evaluate local haemodynamical conditions of individual AoR elements.
  
  
  METHODS
  In the experimental set-up, the David procedure was performed on 10 domestic pigs. Data were compared with the measurements obtained in 10 native AoRs. In each AoR, six high-resolution ultrasonometric crystals (200 Hz) were implanted, being positioned at each commissure and at the AoR base. 3D geometrical deformation of the AoR, torsion and tilt angle was determined. Computed fluid dynamics (CFD) simulation analysis was used to evaluate local pressure, flow and shear stress.
  
  
  RESULTS
  In David AoRs, the tilt angle was maximal at a peak ejection of 25.9 ± 1.49° and minimal at the end of isovolemic contraction at 23.5 ± 0.80°. David root rotation was maximal at a peak ejection of 27.93 ± 1.54° and minimal at the end of the isovolemic contraction at 25.7 ± 1.32°. In the native AoR, the opposite was observed. Here, the tilt and rotation angle were maximal at the end of isovolemic contraction (17.25 ± 0.68° and 19.71 ± 0.73°) and decreased to its minimal values at peak ejections (14.1 ± 0.62° and 16.33 ± 0.47°). In David AoR, high pressure (>140 mmHg) combined with low-to-moderate shear stress (0-40 Pa) was found at the leaflet body from the beginning of isovolemic contraction till the opening of the aortic valve. Similar high pressure (>140 mmHg) and shear stress (0-40 Pa) were found in the period from aortic valve closure till the beginning of the isovolemic contraction. In native AoRs, high pressure (>95 mmHg) was conjoined with low-to-moderate shear stress (0-30 Pa) at the leaflets and was registered at the end of isovolemic contraction.
  
  
  CONCLUSIONS
  The David AoR is haemodynamically less favourable when compared with the native AoR. During almost two-thirds of the time period of the cardiac cycle, AoR elements are exposed to high pressure and low shear stress. In contrast, in native AoRs, similar conditions were present only during the short period of isovolemic contraction.
authors.affiliation: Department of Surgery and Anesthesiology, Cardiovascular Research, University Hospital Lausanne, Lausanne, Switzerland denis.berdajs@bluewin.ch.
authors.forename: Denis
authors.initials: D
authors.lastname: Berdajs
authors.affiliation: Department of Surgery and Anesthesiology, Cardiovascular Research, University Hospital Lausanne, Lausanne, Switzerland.
authors.forename: Selim
authors.initials: S
authors.lastname: Mosbahi
authors.affiliation: Swiss Federal Institution of Technology Zürich, Zürich, Switzerland.
authors.forename: Zalan
authors.initials: Z
authors.lastname: Forro
authors.affiliation: Department of Surgery and Anesthesiology, Cardiovascular Research, University Hospital Lausanne, Lausanne, Switzerland.
authors.forename: Marco
authors.initials: M
authors.lastname: Burki
authors.affiliation: Department of Surgery and Anesthesiology, Cardiovascular Research, University Hospital Lausanne, Lausanne, Switzerland.
authors.forename: Ludwig K
authors.initials: LK
authors.lastname: von Segesser
mesh_terms: D000818:Animals; D001011:Aorta / Q000503:physiopathology / Q000601:surgery*; D001021:Aortic Valve / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000601:surgery*; D001794:Blood Pressure / Q000502:physiology; D019917:Blood Vessel Prosthesis Implantation / Q000379:methods*; D003198:Computer Simulation; D006439:Hemodynamics; D021621:Imaging, Three-Dimensional; D008955:Models, Cardiovascular; D011184:Postoperative Period; D013314:Stress, Mechanical; D034421:Sus scrofa; D014463:Ultrasonography
keywords: Aortic root; Aortic root aneurysm; Aortic root sparing procedure; Haemodynamics