Biomedical Engineering Reference
In-Depth Information
Fig. 10
Pressures inside
aneurysm sac on zone 1 (see
Fig.
8
a) for different
stent-graft material properties
These simulation results imply that the pressure variations within the aneurysm
sac are related to the displacement of the stent-graft caused by the luminal pressure.
If this is the case, the placement of one sensor on the region with less structural
stability (higher displacement) might be a good indicator, when compared to another
sensor placed elsewhere within the aneurysm sac, of the structural integrity of
the stent-graft. These results also suggest that the pressure variations inside the
aneurysm sac are related to the stent-graft material (structural behavior). Results
for the same simulation boundary conditions but using a higher Young's Modulus
for the stent-graft material, E
60 MPa, Fig.
10
, confirm the assumption that the
pressure within the aneurysm sac depends on the structural behavior of the stent-
graft material. In fact, simulations reveal that a large drop on the pressure within the
aneurysm (>10 mmHg) sac occurs when the Young's Modulus is increased from
10MPato60MPa.
The abdominal aortic aneurysm CFD (Compute Fluid Dynamics) model with FSI
is a suitable tool to study pressure changes within the aneurysm and indicates that
pressure sensors can be used to detect post-EVAR complications. Pressure sensing
in the aneurysm sac can be used both for leakage detection and to measure systolic
and diastole blood pressures. If more than one sensor is used, model results suggest
that the differences in pressure within the aneurysm sac can be an indicator of the
stent-graft material integrity.
D
9
Development of a Flexible Pressure Sensor
A key component for the smart stent-graft is the pressure sensor. The sensing
element must be flexible to enable its conformability to the stent-graft and thus
the aorta. Such features allow the attachment of the sensor to the stent-graft and
their deployment in a single step (as opposed to the requirement of two catheters
