Artificial heart

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


The Human Heart

Right and left atria receive bloodRight and left ventricles pump bloodValves produce one-way blood flow

from atria ventricles arteriesEnergy to pump blood comes from

nutrients and oxygen in bloodThe blood supply to the heart is

provided by coronary arteries


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!


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


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)


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)


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 clotsDamage to red blood cellsLack of pulsatile blood flow?


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


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

Identify Problem

Specify Criteria

Implement Design

Test Design

Refine Design


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


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!


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


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


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


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


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

Health & Medicine

Artificial heart