The Artificial Heart: A Design Example BIOE 1000 October 18, 2001

We bring life to engineering! The Human Heart Heart has four chambers Right chambers pump blood to lungs to receive oxygen Left chambers pump oxygenated blood from lungs to rest of the body

We bring life to engineering! The Human Heart Right and left atria receive blood Right and left ventricles pump blood Valves produce one-way blood flow from atria  ventricles  arteries Energy to pump blood comes from nutrients and oxygen in blood The blood supply to the heart is provided by coronary arteries

We bring life to engineering! Heart Disease Heart attack: blockage of coronary artery damages portion of heart muscle Congestive heart failure: gradual weakening of heart Millions suffer from heart disease – Many cases are treatable with lifestyle changes, drugs and/or surgery – Surviving patients suffering from most severe cases need new hearts!

We bring life to engineering! The Need for a Heart Substitute 100,000 Americans/year suffering from severe heart disease need new hearts Only 2,000 patients receive heart transplants Conclusion: many patients die waiting for a new heart! A suitable alternative to donor hearts could prolong thousands of lives

We bring life to engineering! History of Heart Substitutes WWII: first open heart surgeries 1953: heart-lung machine successfully used during heart surgery 1958: Drs. Willem Kolff and Tetsuzo Akutsu sustain a dog for 90 minutes with a PVC artificial heart 1967: Dr. Christian Barnard transplants a donor heart into a 59 year old man (he survived 18 days) PVC heart (1958)silicone heart (1965)

We bring life to engineering! History of Heart Substitutes 1969: Dr. Denton Cooley uses an artificial heart to sustain a patient waiting for a donor (survived 3 days) 1972: Cyclosporine introduced to suppress immune responses of transplant recipients 1982: Dr. William DeVries implants the Jarvik-7 artificial heart into Dr. Barney Clark (he survived 112 days) Liotta heart (1969)Jarvik-7 (1982)

We bring life to engineering! Why Heart Substitutes Fail Immune response “rejects” transplant or side effects due to immune suppression Infection due to tubes and wires passing through skin Formation of clots Damage to red blood cells Lack of pulsatile blood flow?

We bring life to engineering! Design Process Identify the problem or need to address Specify details/criteria of an adequate solution to your problem Implement various solutions that meet the criteria you specified Test to determine which solution is most viable Further testing to refine the solution you chose

We bring life to engineering! Design Refinement Process is iterative – You need to repeat various steps after testing – Make design changes based on test results Failed designs – Design didn’t meet criteria – Could be due to inappropriate criteria

We bring life to engineering! Criteria for a Heart Substitute Must fit into chest cavity and connect to atria, pulmonary artery and aorta quickly Provide an adequate blood flow (8 – 10 liters/min) Send deoxygenated blood to the lungs and oxygenated blood to the body Operate continuously for an indefinite period of time Provide adequate warning if something is wrong or if it is going to fail

We bring life to engineering! Criteria for a Heart Substitute Should increase/decrease blood flow based on patient activity level Should not evoke an immune response No wires or tubes that penetrate the skin Should not produce blood clots Should not damage red blood cells Ideally should have pulsatile blood flow Many others we haven’t thought of!

We bring life to engineering! The AbioCor ® Heart Implanted into 59 year old Robert Tools on July 2, 2001 at Jewish Hospital in Louisville KY (96 days) Patient is able to walk around, organs are functioning normally, undergoing daily rehabilitation for eventual release

We bring life to engineering! How the AbioCor ® Heart Works Hydraulic pump forces blood to lungs and body Power is provided by an internal rechargeable battery Battery is recharged by coils on surface and below skin Internal controller monitors system and controls pump speed

We bring life to engineering! Surgical Procedure Implant controller, battery and coil Connect patient to heart-lung machine Cut away ventricles Sew grafts onto atria and arteries Connect implants to grafts Remove patient from heart-lung machine

We bring life to engineering! AbioCor ® Design Criteria Grapefruit size, weighs 2 lbs, requires a 7 hour surgery for implantation Can provide up to 8 liters/min of blood to the lungs and body Has two chambers for pumping deoxygenated blood to the lungs and oxygenated blood to the body Wireless energy transfer system allows for continuous operation Internal controller monitors operation

We bring life to engineering! AbioCor ® Design Criteria Internal controller increases/decreases blood flow based on blood oxygen levels Materials are inert to the immune system Completely contained within the chest – no wires or tubing through skin! Made of special materials and special pump design to prevent clots and RBC damage Pumping alternates between chambers, creating a pulsatile blood flow