Download Dennis Ceh describes his work for Robart`s Imaging, part of the

Development of a Dynamic Heart Phantom for Verification
of Minimally Invasive Surgical Interventions
Dennis Ceh ([email protected])
University of Windsor, Windsor, Ontario, Canada
Medical Problem
Design Decisions
Mitral valve regurgitation (MVR)
• Polyvinyl Alcohol cryogel (PVA-c) was used since it behaves similar to tissue, especially under ultrasound [2]
• Is a disorder of the heart that occurs when the mitral
valve does not properly close allowing blood to leak
from the left ventricle back into the left atrium
• Only needed to recreate elements that directly impact the motion of the mitral valve. That is the left ventricle, aortic
valve and mitral valve.
• Affects 2-6% of the population [1]
• Trabeculae were added to both inside and outside of left ventricle to allow left ventricular twisting
• Dangers include stroke and congestive heart failure
(due to inadequate circulation)
• Braided silk sutures were used to represent the chordae tendineae
• Large number of cases (up to 49%) are inoperable with
conventional surgical techniques due to co-morbidities
Results Continued
• Left ventricle was approximated as a hemi-ellipsoidal shape with volume of 135 ml (diastolic state).
• An actuator system composed of pneumatic cylinders was used to compress the left ventricle
Phantom setup with Philips ie33 US machine
Overall Work Flow
Design molds
in CAD system
Create molds
with 3D printer
Solidify PVA-c with
freeze/thaw cycles
www.heart-valve-surgery.com
Inject molds
with PVA-c
Assemble phantom
Use system with
Neochord tool
TEE Probe
Resulting ultra sound image
Further Work
Medical Intervention
The Neochord DS1000 is a minimally-invasive technology designed for mitral valve repair by adding new synthetic chordae tendineae. Procedure is performed with
the aid of ultrasound (trans-esophageal echo or TEE).
• Try other tissue mimicking materials (silicone, PVC)
Results
• Add 30◦ angle between mitral valve and aortic valve
(which also impacts left ventricle design).
• Improve upon the actuator system; allow different
heart rates, manual control and computer interaction
• Create different versions of the mitral valve to simulate
various issues
• Improve the general setup and assembly of the phantom
In the images below: a) the neochord tool is navigated
close to the mitral valve; b) the required leaflet is pierced;
c) removal of the tool and fastening the new chordae; and
d) the new chordae being used
(a)
References
Mitral Valve Mold
Aortic Valve Mold
Left Ventricle Mold
[1] Freed L, Levy D, Levine RA, et Al. Prevalence
and clinical outcome of mitral-valve prolapse. New
England Journal of Medicine, Jul 1 1999; 341(1):1-7
[2] Surry KJ, Austin HJ, Fenster A, Peters TM. Poly(vinyl
alcohol) cryogel phantoms for use in ultrasound and
MR imaging. Imaging Research Laboratories, Robarts Research Institute, London, Canada
Acknowledgements
(b)
Special thanks for all the help to John Moore (Imaging Group,
(c)
(d)
www.neochord.com
Phantom side view
Mitral and Aortic Valves
With NeoChord Tool
Robarts Research Institute) and Gerard Guiraudon (Canadian
Surgical Technologies and Advanced Robotics, Lawson Health
Research Institute, London Health Science Center, and the
Imaging Group, Robarts Research Institute).