Numerical analysis of the 3-dimensional aortic root morphology during the cardiac cycle.
OBJECTIVE
The aim was to define the 3-dimensional (3D) geometrical changes of the aortic root and to determine the local shear stress profile of aortic root elements during the cardiac cycle.


METHODS
Six sonomicrometric crystals (200 Hz) were implanted into the aortic root of five pigs at the commissures and at the aortic root base (AoB). 3D aortic root deformation including volume, torsion and tilt angle were determined. Geometrical data with measured local flow and pressure conditions was used for computed fluid dynamics modelling of the aortic root.


RESULTS
Compared with end-diastole, the sinotubular junction and AoB have maximal expansion at peak ejection: 16.42 ± 6.36 and 7.60 ± 2.52%, and minimal at isovolaemic relaxation: 2.87 ± 1.62 and 1.85 ± 1.79%. Aortic root tilt and rotation angle were maximal at the end of diastole: 17.7 ± 8.8 and 21.2 ± 2.09°, and decreased to 15.24 ± 8.14 and 18.3 ± 0.1.94° at peak ejection. High shear stress >20 Pa was registered at peak ejection at coaptations, and during diastole at the superior two-thirds of the leaflets and intervalvular triangles (IVTs). The leaflet body, inferior one-third of the IVTs and valve nadir were exposed to moderate shear stress (8-16 Pa) during the cardiac cycle.


CONCLUSIONS
Aortic root geometry demonstrates precise 3D changes of tilt and rotation angle. Reduction of angles during ejection results in a straight cylinder with low shear stress that facilitates the ejection; the increase during diastole results in a tilted frustum with elevated shear stress. Findings can be used for comparative analysis of native and synthetic structures with individual compliance.
Department of Surgery and Anesthesiology, Cardiovascular Research, University Hospital Lausanne, Lausanne, Switzerland denis.berdajs@bluewin.ch.
Denis
D
Berdajs
Department of Surgery and Anesthesiology, Cardiovascular Research, University Hospital Lausanne, Lausanne, Switzerland.
Selim
S
Mosbahi
Swiss Federal Institution of Technology Zürich, Zurich, Switzerland.
Zalan
Z
Forro
Department of Anesthesiology, University Hospital of Zürich, Zurich, Switzerland.
Christof
C
Gerber
Department of Surgery and Anesthesiology, Cardiovascular Research, University Hospital Lausanne, Lausanne, Switzerland.
Enrico
E
Ferrari
CFS, Engineering, Lausanne, Switzerland.
Dominique
D
Charbonnier
Department of Surgery and Anesthesiology, Cardiovascular Research, University Hospital Lausanne, Lausanne, Switzerland.
Ludwig K
LK
von Segesser
D000818:Animals; D001021:Aortic Valve / Q000033:anatomy & histology* / Q000502:physiology; D001696:Biomechanical Phenomena; D006321:Heart / Q000033:anatomy & histology* / Q000502:physiology*; D006439:Hemodynamics / Q000502:physiology; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008955:Models, Cardiovascular; D013314:Stress, Mechanical; D013552:Swine
Aortic root; Computed fluid dynamics; Geometry of the aortic root; Shear stress