Stress analysis of the aortic valve with and without the sinuses of valsalva.

BACKGROUND AND AIM OF THE STUDY: In some patients with dilated aortic root, attempts have been made to replace the aorta and preserve the anatomically normal leaflets. The tubular Dacron graft used in the valve-sparing procedure does not have the sinuses of Valsalva, and therefore might adversely affect the valve. The effect of the presence or absence of the sinuses was investigated on stresses in the leaflets.
METHODS: Finite element models of the tubular aortic root and the root with the sinuses were constructed. The model dimensions were: aorta radius 13 mm; valve height 18 mm; leaflet thickness 0.5 mm; aorta and sinus wall thickness 1.3 mm. In the root with the sinuses, each leaflet-sinus unit formed a cylindrical geometry. The model was loaded with an internal pressure of 80 mmHg (0.01 N/mm2) and the stress determined.
RESULTS: The stress in the leaflet belly was 0.26 N/mm2, and not affected by the geometry and stiffness of the root. In the tubular root there was a stress concentration along the leaflet attachment, and the stress reached 0.65 N/mm2; in contrast, in the sinus root there was no stress concentration and maximum stress was only 0.3 N/mm2. Under pressure, the leaflet-sinus assembly expanded in a uniform manner, whereas in a tubular root large deformations occurred along the leaflet attachment.
CONCLUSION: The sinuses of Valsalva play a very important role in minimizing stress in the leaflets; thus, use of the sinus graft is expected to enhance the longevity of the spared valve.