Flat or Curved
Pericardial Aortic Valve Cusps: A Finite Element Study
Khee Hiang Lim, Johanes Candra, Joon Hock Yeo, Carlos M. G. Duran
Nanyang Technological University, School
of Mechanical and Production Engineering, Singapore, The International
Heart Institute of Montana Foundation at Saint Patrick Hospital and
Health Sciences Center and The University of Montana, Missoula, Montana,
USA |
Background and aim of the study: The finite element
method (FEM) has frequently been used to investigate the behavior of
the aortic valve, but studies on the performance and behavior of free-hand
autologous pericardial aortic valves reconstructed using specially designed
valve molds have not been performed. The study aim was to demonstrate
the effectiveness of a three-dimensional (3-D) cusp of the authors’ design
(H-Mold) versus a two-dimensional (2-D) (flat) cusp using a FEM to compare
stress distribution and leaflet contact properties.
Methods: Solid models of the aortic root and valve cusps
were constructed using a computer-aided design package. All models
had different free edge lengths and surface areas, but a constant
leaflet attachment length corresponding to a 19 mm annulus diameter.
A static pressure of 80 mmHg was applied to
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all models.
Results: The maximum von Mises stress value in the H-Mold
at the cusp commissure was 34.5% lower than the stress value in the
flat leaflet, while the contact area in the H-Mold leaflet was 85.7%
greater than that of the flat leaflet. The length of leaflet free
edge greatly influenced maximum von Mises stress intensity at the
commissures, and the contact area between leaflets was mainly affected
by the geometric shape of the leaflet and its surface area.
Conclusion: 3-D leaflet geometry was found positively
to influence leaflet stress distribution and coaptation. This geometry
should have a significant impact on the reliability and long-term
durability of pericardial aortic valve reconstruction.
The Journal of Heart Valve Disease 2004;13:792-797 |