Biomedical Engineering Reference
In-Depth Information
Fig. 11.2
Delamination
profiles for (
A
) three LONG
and (
B
) three CIRC strips cut
from the same BAV
aneurysm. The
dashed lines
represent the average of the
mean values of
T
peel
for all
LONG and CIRC strips and
were taken as the
S
d
in
LONG and CIRC directions
for the patient, respectively.
Taken from Pasta et al. (
2011
)
the non-aneurysmal aorta as a function of aortic diameter. Results suggest that even
with corrections of age or aneurysm diameter the
S
d
of TAV ATAAs still remains
higher than that of BAV
ext
, see Figs.
11.4
(A) and
11.4
(B).
A comparison of
S
T
of non-aneurysmal and aneurysmal tissues for both INT-
DEL and ADV-DEL halves following the delamination tests in LONG and CIRC
orientations was performed, see Figs.
11.5
(A) and
11.5
(B). In all cases, the
S
T
of
the CIRC strips was found to be higher than that of LONG specimens, and the INT-
DEL half is significantly weaker than the ADV-DEL half. It should be also noted
that the ultimate tensile strength of BAV ATAAs is higher than that of TAV ATAAs,
though not significantly different. This trend is opposite of that observed for the
delamination testing.
SEM imaging of the dissected surfaces for the healthy aorta reveals that the de-
lamination in the LONG direction creates a remarkably 'rougher' surface compared
to the surfaces from CIRC specimens (Fig.
11.6
(A)). Similar failure surfaces were
found for both BAV and TAV ATAAs; however, they appeared rougher than those of
normal aorta (Fig.
11.6
(A)). At high magnification, a 'fiber bridging' failure modal-
ity, which occurs when the dissection switches from one fiber/matrix interface to
