Faculty
We have received useful feedback from our Stanford faculty mentors and project sponsors at Guidant Preclinical R&D. Dr. Charles Taylor suggested the use of the circuit simulation software, CircuitMaker 2000 for the design of cardiovascular flow systems. This program again proved useful in designing the circuit to actuate the heart valves.
Sponsor
When it became clear that it would be difficult to achieve
physiologic conditions in all of the branching arteries simultaneously, our
sponsors suggested that we develop recommended settings for each target area. Designers and physicians will only deploy a
device in one area of the model (primarily the coronary arteries) at one time
and therefore we could compromise the accuracy of flow conditions in the other
arteries. This simplified the design of our flow model significantly. They also
cautioned us that during the design of the flow model we position the flow
restriction valves out of the fluoroscopic field of view. Additionally, our sponsors were interested to
know how the presence of disease sites in the coronary arteries affected the
flow rate through the model. Diseased coronaries
are frequently used for device testing and our sponsors will be unable to
measure the arterial pressure and velocity in their lab.
Finally our sponsors at Guidant feel that our fluoro-compatible bi-phasic beating heart is sufficiently novel and non-obvious to be patented.
Vendor
We had intended to have our heart model positives manufactured
at the Guidant rapid prototyping facility in Temecula, CA but our heart model
was very complex and their older stereolithograpy (SLA) equipment could not
handle it. We had similar problem trying
to load our files onto FDM in the Stanford Product Realization Lab. Outside
vendors quoted us a price for the five heart models that exceeded our entire
project budget. Scott McMillan, a representative of Javelin 3D suggested we
fabricate our heart mold positives by 3D-printing instead of expensive
Executive Committee feedback
The executive committees were helpful in monitoring the progress of our project. Feedback from the Reliability and Validation committee at the project definition phase of the project ensured that we had established quantitative criterion by which to evaluate the model. The Technical Resources committee advised us that careful selection of flexible and strong materials for heart walls would be necessary. The Design Review committee cautioned us that synchronizing the flow model with the heart wall motion would not be easy. The Project Management committee suggested that we develop the flow model and beating heart prototype in parallel given the time available.