Pumps for Human Blood Pressure Simulation - Microsurgery: Advances, Simulations, and Applications - page 216

F a 0 F a 3 for stress ranges R 2 and R 3 and values that may be considered
normal high for other parameters.
We must consider that we used a ixed image to calculate the
value of the optical path length in all pixels. Image N 5 represents
considerable deformation in the blood vessel model and high
birefringence. In N a 5 , the deformation of the blood vessel model by
the guide wire is not visible and where this deformation occurs the
stress measurements accuracy is compromised. For this reason,
values of N a 5 are close to normal high values. This problem is solved
by calculating the optical path length for all images. To implement
real-time stress analysis solving this problem, a prismatic lens may
be used enabling simultaneous use of two cameras, one with a
polarizer and the other without.
For building a system that evaluates medical tools and human
skills in real time, complementary stress measurement methods
that use pressure sensors within the catheter [8] are not suitable, as
introducing foreign objects into the catheter increases its stiffness
and changes its original design and functions. Therefore, the number
of possible evaluations with these sensors is limited. Human blood
pressure levels are useful for calibrating the stress-analysis software,
as they give a reference of normally high stress levels, as in this
chapter stress due to pressure variation inside urethane vasculature
models was compared quantitatively to stress produced with a
guide wire. This methodology is applicable to catheter insertion
robots safety evaluation [9-10], and comparison of medical tools
performance and surgical skills. The simulation of human blood
pressure is important also for the in-vitro environment as interaction
between silicone vasculature with medical tools (catheters, stents,
grafts, and coils) becomes more realistic, enabling better evaluation
of tools prototypes.

6.5 Blood Pressure Simulation in Saccular

Aneurysm Model with Bleb

During the aneurysm-growing process in cerebral arteries, a blister
called bleb appears in the aneurysm membrane areas with low shear
stress. The relation of the presence of the bleb with the rupture
possibilities in aneurysm is being investigated [11]. Provided the
presented techniques for stress measurements, in this section, we