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The Artificial Heart:A Design Example

BIOE 1000

October 18, 2001



We bring life to engineering!

The Human Heart Heart has four

chambers

Right chamberspump 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 blood

Right and left ventricles pump blood

Valves produce one-way blood flowfrom atriap ventriclesp arteries

Energy to pump blood comes from

nutrients and oxygen in blood The 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 weakeningof 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 hearttransplants

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 duringheart surgery

1958: Drs.Willem Kolff andTetsuzo Akutsu sustain adog for 90 minutes with aPVC artificial heart

1967: Dr. Christian Barnardtransplants a donor heartinto a 59 year old man (hesurvived 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 DeVriesimplants 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 ³rejects´ 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?




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 meetcriteria

± Could be due to

inappropriate criteria

dentify Problem

Specify Criteria

mplement Design

Test Design

efine 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 ± 10liters/min)

Send deoxygenated blood to the lungs andoxygenated blood to the body

Operate continuously for an indefinite periodof time

Provide adequate warning if something iswrong 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 onJuly 2, 2001 at Jewish

Hospital in Louisville KY(96 days)

Patient is able to walkaround, organs arefunctioning normally,undergoing dailyrehabilitation for eventual release




How the AbioCor ® Heart

Works Hydraulic pump forces

blood to lungs and body

Power is provided by aninternal rechargeablebattery

Battery is recharged bycoils on surface andbelow skin

Internal controller monitors system andcontrols pump speed




Surgical Procedure Implant controller,

battery and coil

Connect patient toheart-lung machine

Cut away ventricles

Sew grafts onto atriaand arteries

Connect implants tografts

Remove patient fromheart-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 thelungs and body

Has two chambers for pumpingdeoxygenated 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

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