PIV/CFD
What software does the lab use for CFD?
COMSOL and Ansys
What does SMP stand for?
Shape Memory Polymer
What valve is the team looking at?
What two directions does the biaxial tester stretch tissue in?
circumferential and radial
What fiber is the optical team looking to visualize?
collagen fiber
What valve is the histology team mapping?
tricuspid valve
What metal is the team investigating?
Molybdenum
What does RHS stand for?
Right heart simulator
What aneurysm models was Phiphi using for PIV and CFD?
Testing an idealized saccular aneurysm geometry based off of the middle cerebral artery
4mm
8mm
12mm
What is the definition of a shape memory polymer?
a smart material that can be deformed and returned to its original shape when triggered by an external stimulus
What platform is the team using?
VALVEFIT Platform
What valve is Shubi investigating?
Mitral Valve
What is electrospinning?
Technique that utilizes electric forces to produce nanofibers
What is the full heart team designing?
a flow loop system able to fix a whole heart under specific pressures
What is the importance of a sterile culture procedure for the degradation team?
Prevent cross contamination
Ensure reliable and reproducible experimental results
How many chambers does the RHS system have?
3 interconnected chambers:
Atrial, Ventricle, and Bladder Pump
What is RI matching used for in PIV?
validation for the water/glycerol mixture being used-eliminates optical distortion and light reflection when imaging through transparent solid boundaries
ensures the working fluid and the solid model have the same refractive index-makes sure researchers can clearly track the tracer particles without any visual distortions or aberrations
What are Hannah's plan with using the Gcode for the 3D printer? What does it have to do with the SMP project?
Software/library that allows precise print paths for 3D Printing
Allows to print specialized
Useful for small-scale & complicated prints
Mainly using Python
Use:
Recreating SMP templates for faster, more successful printing
Creating SMP templates with different infill patterns for use
What is the annulus?
fibrous ring that anchors a heart valve's leaflets to the heart muscle
What are the three parts of Shubi's project?
Part 1: time interval, part 2: biaxial mechanical testing, part 3: data analysis
Why can't the electrospinning team use metal rail covers and metal items in their setup?
the metal affects where the fibers will collect (metal is conductive)
What is the full heart team adjusting to change the pressure in the heart?
adjusting the height of the elevated reservoir relative to the heart chamber
Why does the metal degradation team use an incubator?
Purpose:
Temperature Regulation: constant, precise temperature
Atmosphere Control: Regulates and levels CO2
Humidity Control
Sterile Controlled Environment
overall- mimics physiological parameters/conditions
What are the cameras used for in the RHS?
optical flow analysis of tricuspid valve leaflet strain
Briefly describe how PIV works
optical method used to visualize and measure fluid flow by tracking tracer particles in a liquid
provides velocity maps over different geometries
What is the significance of Andrea's project (Examine the durability, shape retention, and recovery time of SMP foam)?
confirm the SMP does not degrade over time due to mechanical stress- degradation could harm patients and compromise effective treatment
What data is the team using and what are they doing with it?
4D echocardiographic image data
they are creating a 3D point cloud by manually placing points on the valve
What model does the biaxial team use to create/predict the stress strain curve?
Fung type model
What is the importance of using an electrospinning setup?
Importance
Fast, easy way to generate scaffolds
Used in various medical applications
I.e. scaffold creation nerve regeneration, heart valve tissue engineering
Can mimic extracellular matrix (ECM)
Why is the full heart team fixing the whole heart-what are they going to be looking for/studying?
changes in the valvular interstitial cells and extracellular tissue structure under different pressure loads using histology
What are the purposes for the preliminary degradation experiment?
Evaluate early-stage degradation behavior of molybdenum
Establish sterile, controlled baseline conditions before any other experiments
To monitor pH and ionic changes caused by Mo exposure
What is the project goal?
Project Goal: Developing a benchtop circulatory flow loop to replicate right heart physiology, incorporating a tunable system that allows users to adjust key hemodynamic parameters including heart rate, temperature, flow rate, and pressure, while quantifying leaflet strain via optical flow analysis. The system features an interchangeable valve slide mechanism to accommodate a range of prosthetic valves, including artificial and eventual native valve integration, varying in material composition and geometric design to suit the testing need.
Name one issue the CFD team is facing or an avenue of research they are looking into
smaller stent, blood viscosities, patient specific geometries etc.
What is the significance of Jaime's project for SMP?
you can see SMP under x-ray imaging with barium sulfate- but unable to determine orientation. Adding tungsten (which appears brighter than barium) could be used to understand/see the orientation of the SMP in vivo
What is the goal for the 3D point clouds created by the image segmentation team?
to use these to train an AI model to distinguish the valve from 4D echocardiographic images
Automate the system so it can overlay point clouds on the tricuspid valve of any patient.
What were Shubi's results for her time interval study?
that most elastin was degraded by 9 minutes
What is the mechanism of spatial frequency domain imaging? (how does it work)
Spatial frequency domain imaging (SFDI)
Optical technique that measures how tissue scatters/absorbs light
Mechanism
Patterned light is projected onto a tissue which interacts with the tissue’s structure
Camera captures how the structure changes the reflected light pattern
MATLAB mathematical model converts changes in light into data maps
Purpose
Allows us to visualize collagen fiber orientation at different depths and quantifying how light interacts with tissue
What are the stains the histology team can do in lab?
H&E, trichrome, pentachrome
What is the overall parts of the procedure for the preliminary degradation experiment?
Procedure:
Collect media from Mo samples
Monitor pH and weight changes
Note any physical differences through optical images
Why is the team looking into the right side of the heart?
Hypoplastic Left Heart Syndrome (HLHS):
Left side of an infant’s heart is underdeveloped
Right side of the heart to be overloaded
~30% of HLHS patients develop tricuspid valve regurgitation
Name one issue the PIV team faced this quarter or one thing they mentioned that needs to be improved going forward
answers may vary
Name and describe one problem the SMP team faced this quarter
could describe any of the following:
vacuum pump, clear PVA, cleaning the synthesis solution off of things, tungsten issues
What are the end goals of the image segmentation team?
Use the geometric representations of the valve for FEM simulations to predict valvular stress and strain.
Enable automated patient-specific modeling for the future development of direct image-to-analysis platforms.
What is one result found in Shubi's biaxial mechanical testing of her elastin degraded valves?
Increased compliance (stretch shift): Elastase treatment shifts the biaxial curves to higher stretch values, indicating reduced tissue stiffness.
Directional sensitivity (anisotropy): Creep is greater in the X-direction than in the Y-direction, showing that the tissue is structurally looser along the X-axis after elastin degradation.
Preserved viscous response: The creep plateau slopes remain similar, suggesting elastin mainly affects immediate elastic behavior.
Delayed stress development: A larger toe region indicates that elastin supports low-strain loading and delays the sharp rise in stress.
Name an issue the electrospinning team ran into this quarter
We were unable to identify the specs of the motor and we were unable to tell if tachometer had accurate rpm measurements. We also do not know the max rpm speeds. RPM controller only says “0” and “100” which is very vague.
The electrospinner did not have some of the 3D printed covers that were shown in the pictures given to us. We only had access to the metal covers which are unusable because it would encourage polymer deposit on the covers instead of the spinning collector.
Flash Drive with previous electrospinner project information became corrupted which meant we had access to limited information.
Original tachometer sensor holder was very unstable and was redesigned to be incorporated into the motor cover. Entire set-up was also very unstable and shook at high rpm speeds.
The mandrel broke off of where it connected to the motor and must be hot glued back on.
Why is the histology team mapping the tricuspid valve?
Goal: Create a stitched microscopic image map of porcine tricuspid valve (TV) using H&E and pentachrome staining.
Significance: Gain better understanding of the TV ECM structure across all three leaflets.
Describe the Acrylic study the metal degradation team is doing
Embedding molybdenum samples in acrylic “freezes” sample to exactly how it was when study concluded
Allow precise surface degradation analysis without interference from environmental condition
Reduces contamination in samples
Allows us to cut sample in half for microscopic analysis
Thickness of oxide layer
Embedding to protect oxide layer
Get cross sectional value
Name a future direction of the RHS
Future Directions:
Remove edge effects within ventricle box
Native tissue integration
Undergo iterative testing of the 3D printed native tissue mount
Dissection and suturing of native heart valves
PIV (particle image velocimetry) implementation
Visualize velocity fields to help with shear stress/hemodynamics analysis