Developing a Cardiovascular Model

1. Developing a Cardiovascular Model James Clear Chase Houghton Meghan Murphy

2. 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

3. 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.

4. Performance Criteria • Cardiovascular Model Specifications • Water tight • Portable • Anatomically representative • Axial Pump for generating pressure gradient in venous system • Aesthetically pleasing • Hingeable heart

5. 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.

6. 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

7. 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

8. 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

9. 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

10. 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

11. Synthesis—System and Environment www.cvcu.com.au/images/cv_torso.jpg

12. Model Heart http://medical-dictionary.thefreedictionary.com/bioprosthetic+valve

13. Design • Dimensions • Inferior Vena Cava – 1 in interior Diameter (avg. diameter 20 mm) • Femoral Vein- .5 in interior Diameter (avg. diameter 10 mm) • 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

14. Portableand quickly assembled • Aesthetic • Easily Viewable Experiment Block Diagram • Design features to implement functions • Test Model Functionality • Refine • FINAL DESIGN • Closed Circuit • Hinge Heart • Pump • No Leaks • Determine heart functions to mimic

15. 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

16. References • 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.