Download Developing a Cardiovascular Model

Developing a
Cardiovascular Model
James Clear
Chase Houghton
Meghan Murphy
Problem Statement
• No all-purpose cardiovascular model is
currently commercially available.
– Models are made for testing of a particular device
exclusively
– No in vitro model exists for physicians to learn and
visualize cardiac procedures
• Current model exists from last semester but
has design flaws and performance
shortcomings
Problem Statement:
Currently Available Technology
• Patented model for fatigue testing of prosthetic tricuspid
valve replacements. Model applies pressure on valve to
mimic in vivo forward and backflow gradients.
• Agar gel model with characteristics of biological tissue used
to model left ventricular and aortic chambers. Ultrasound
imaged flow dynamics through bicuspid valve.
• Model testing ventricle assist devices pumping
performance and quantifying flow dynamics. Resistance
comparable to native heart present.
• Patented teaching model for complex cardiac surgery
including repair of congenital heart defects. Clay open
system model with detachable colored tubes.
Performance Criteria
– Cardiovascular Model Specifications
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Water tight
Portable
Anatomically representative
Axial Pump for generating pressure gradient in venous
system
• Aesthetically pleasing
• Hingeable heart
Primary Objective
It is the purpose of this team to use the
previously established model as a foundation
for developing a heart model of the inferior
venous flow, and potentially interchangeable
model of inferior arterial flow, which may be
easily visualized and modulated.
Solution Description
Develop a cardiovascular model with the following
requirements
• Insert and visualize catheters, intracardiac devices
intended for septum, and deliver stents
• Apply venous flow (10 mmHg) to improve anatomical
representation
• Introduce medical professionals and students to
protocols and devices
Solution Description:
Adaptations to Current Design
• Remove upper half – decrease size, increase
portability
• Connect pump to simulate blood flow through
veins
• Acrylic tubes – prevent leaking, withstand
pressure created by pump, ability to see inside
vessels
• Access points – various medical devices to be
tested and displayed
Goals
• This model will:
– Be a useful, anatomically accurate tool for
physicians and medical device companies
• Preliminary tests for devices
• Instructional use for physicians
– Be portable in order to transport
Factors
• Cost
– Materials
• Pipes, connectors, valves, heart casing
– Labor/Machining
• Quality
– Design of the new model
• Size, portability, water tight, aesthetically pleasing
• Benefits
– Layout and modularity/size of model
• Potential conversion of venous model to arterial
Performance Metrics
• Outcome measurements
– Ability of devices to be effectively used on the
model
• Catheter manipulation, stent delivery, intrarticular
device mobility
– Ability to transport easily and set up quickly
– Water retention
– Anatomical accuracy
Synthesis—System and Environment
www.cvcu.com.au/images/cv_torso.jpg
Model Heart
http://medical-dictionary.thefreedictionary.com/bioprosthetic+valve
Design
• Dimensions
– Inferior Vena Cava – 1 in interior Diameter (avg. diameter 20
mm)
– Femoral Vein- .5 in interior Diameter (avg. diameter 10 mm)
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Solid Acrylic tubing sealed with Chloroform
Axial Pump generating ~10mmHg pressure
Approximating geometry of the heart
Hinging of right atrium
Bioprosthetic tricuspid valve
Modular construction
Selfhealing polymer to model septum
Experiment Block Diagram
General
Model
Requirements
Determine
Cardiac
Procedures to
test
Portable and
quickly
assembled
Determine heart
functions to
mimic
Easily
Viewable
Aesthetic
Design features
to implement
functions
Test Model
Functionality
Refine
FINAL DESIGN
Improvements
to initial design
Closed Circuit
No Leaks
Hinge Heart
Pump
Validation
• Performance will be assessed by how physicians
interface with device and how realistically the
device models cardiac procedures
• Conclusions will be drawn on how the design
implements intended design features
– Portable, Transparent, Pump, Water-tight
• Physician input will be considered for future
design improvements and used to identify
drawbacks
References
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Appartus for Testing Prosthetic Heart Valve Hinge Mechanism. More RB et al.,
inventors. United States Patent US5531094.
http://www.freepatentsonline.com/5531094.pdf accessed 12 Nov 2009.
Durand LG, Garcia D, Sakr F, et al. A New Flow Model for Doppler Ultrasound Study
of Prosthetic Heart Valves. Journal of Heart Valve Disease. [Internet] 2006 Nov 4
[cited 12 November 2009]; 17. Available from: http://www.icr-heart.com/journal/.
Hertzberg BS, Kliewer Ma, Delong DM et al. Sonographic Assessment of Lower
Limb Vein Diameters: Implications for the Diagnosis and Characterization of Deep
Venous Thrombosis. AJR. May 1997; 168:1253-1257.
Pantalos GM, Koenig SC, Gillar KJ, Giridharan GA, Ewert DL. Characterization of an
adult mock circulation for testing cardiac support devices. ASAIO. Feb 2004;
50(1):37-46.
Pediatric congenital heart defect model. United States Patent US7083418.
http://www.patentstorm.us/patents/7083418/description.html accessed 12 Nov
2009.
Replogle RL, Meiselman HJ, Merrill EW et al. Clinical Implications of Blood
Rheology Studies. Circulation 1967; 36:148-160.