Biomechanical implications of the congenital bicuspid aortic valve: A finite element study of aortic root function from in vivo data
ABSTRACT Congenital bicuspid aortic valves frequently cause aortic stenosis or regurgitation. Improved understanding of valve and root biomechanics is needed to achieve advancements in surgical repair techniques. By using imaging-derived data, finite element models were developed to quantify aortic valve and root biomechanical alterations associated with bicuspid geometry.
A dynamic 3-dimensional finite element model of the aortic root with a bicuspid aortic valve (type 1 right/left) was developed. The model's geometry was based on measurements from 2-dimensional magnetic resonance images acquired in 8 normotensive and otherwise healthy subjects with echocardiographically normal function of their bicuspid aortic valves. Numeric results were compared with those obtained from our previous model representing the normal root with a tricuspid aortic valve. The effects of raphe thickening on valve kinematics and stresses were also evaluated.
During systole, the bicuspid valve opened asymmetrically compared with the normal valve, resulting in an elliptic shape of its orifice. During diastole, the conjoint cusp occluded a larger proportion of the valve orifice and leaflet bending was altered, although competence was preserved. The bicuspid model presented higher stresses compared with the tricuspid model, particularly in the central basal region of the conjoint cusp (+800%). The presence of a raphe partially reduced stress in this region but increased stress in the other cusp.
Aortic valve function is altered in clinically normally functioning bicuspid aortic valves. Bicuspid geometry per se entails abnormal leaflet stress. The stress location suggests that leaflet stress may play a role in tissue remodeling at the raphe region and in early leaflet degeneration.
SourceAvailable from: Giuseppe LimongelliCirculation 06/2014; 129(25):2691-2704. DOI:10.1161/CIRCULATIONAHA.113.007851 · 14.95 Impact Factor
[Show abstract] [Hide abstract]
ABSTRACT: In the recent years, fluid structure interaction (FSI) models of the aortic valve and root have become increasingly common for two main reasons. The medical reason is that millions of patients suffer from aortic valve disorders. The second reason is that this challenging problem combines several fields of computational mechanics. The key motive for these modeling attempts is their potential to shed light on phenomena that cannot be captured in experiments or in simplified models of solely hemodynamics or structural mechanics. The aim of this paper is to review the state-of-the-art FSI methods in general and their application to the aortic valve in particular. A brief overview of the medical background is provided. The numerical methods and appropriate assumptions are then presented with examples of previous aortic valve models, followed by a discussion of the limitation of current models and recommendations for overcoming them in future research. The methods presented in this paper could help readers to choose the modelling approach and assumptions that are most suitable for their goals.Archives of Computational Methods in Engineering 01/2014; DOI:10.1007/s11831-014-9133-9 · 4.14 Impact Factor
Dataset: 2014 ATVB review on CAVD