Kj. Lockie et al., GEOMETRY OF HOMOGRAFT VALVE LEAFLETS - EFFECT OF DILATION OF THE AORTA AND THE AORTIC ROOT, The Annals of thoracic surgery, 56(1), 1993, pp. 125-130
With the increasing interest in aortic homografts as either a free-sew
n valve or whole-root replacement, the effect of internal pressure and
dilation of the aorta and aortic root on valve leaflet geometry has b
een studied. Seven aortic homograft roots were studied, six that had b
een stored in antibiotics and one that had been cryopreserved. The dia
meter of the aorta was determined as a function of internal pressure a
nd correlated with the stress-strain characteristics of the aortic wal
l. Three-dimensional leaflet surface geometry was measured in the ''ne
utral'' position, and the leaflet was characterized by its radius of c
urvature and angle of inclination, using a cylindrical model. The diam
eter of the aorta increased by between 30% and 50% as the dilation pre
ssure increased from 0 to 120 mm Hg. This was consistent with the stre
ss-strain data obtained from strips of the aortic wall in the circumfe
rential direction. The angle of inclination of the leaflet increased f
rom 20 to 80 degrees and the radius of curvature increased from 4 to 1
7 mm as the internal pressure increased from 0 to 80 mm Hg. The open l
eaflet configuration showed a triangular orifice with low bending stra
ins for a dilated root, but increased bending strains with reduced dil
ation pressure. These are important considerations when implanting a f
ree-sewn homograft into the aortic root.