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BIOFLUID DYNAMICS OF THEBIOFLUID DYNAMICS OF THEARTIFICIAL HEARTARTIFICIAL HEART

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From left to right: Sachin Gursahani Eric Ponce Sujit Tatke Mahesh Nagaraju

CONTRIBUTORS

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OUTLINE

Anatomy of the Heart. Physiology of the Heart. Blood & Biofluid properties. Anticoagulants. Vascular and CFD analysis. Artificial Heart systems. Cost of the Procedure. Future advances in the Artificial Heart

development. Conclusions.

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HEART ANATOMY

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HEART ANATOMY (EXTERNAL VIEW)

The heart is a complex muscular pump that maintains oxygen and blood circulation through the lungs and the rest of the body.

The heart pumps about 7200 liters/day.

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HEART ANATOMY (CROSSECTION VIEW)

The heart has four chambers.

Two atria act as collecting reservoirs.

Two ventricles act as pumps.

The heart has four valves for: Pumping action of the

heart. Maintaining

unidirectional blood flow.

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HEART PHYSIOLOGY

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HEART (PHYSIOLOGY)

Deoxygenated blood returns to the heart via the superior and inferior vena cava, enters the right atrium, passes into the right ventricle, and from here it is ejected to the pulmonary artery.

Oxygenated blood returning from the lungs enters the left atrium via the pulmonary veins, passes into the left ventricle, and is then ejected to the aorta.

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BLOOD & BIOFLUID PROPERTIES

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PROPERTIES OF BLOOD

Medium for transporting: dissolved gases, nutrients, hormones and electrolytes.

Removes the waste products of metabolism.

Provides protection against the toxins and pathogens.

Stabilization of pH and temperature of our body. Blood has the property of clotting that prevents the loss of

blood from the body. 

The oxygen is picked up by blood as it passes through the lungs.

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PROPERTIES OF BLOOD (contd.)

Blood is composed of about 46-63 % plasma that contains suspended cells.

Plasma is the fluid component.

Plasma = 92% water + 7% proteins + 1 % plasma solutes.

Proteins include: Hormones Albumins Globulins Fibrinogen

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Plasma is composed of electrolytes organic nutrients organic wastes.

Formed elements= 37-

54 % Red blood cells

(RBC) White blood cells

(WBC) Platelet

PROPERTIES OF BLOOD (contd.)

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PROPERTIES OF BLOOD (contd.)

The rheology of blood is affected due to bypass surgery and due to dilution of plasma by 50%, respectively.

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Intravenous fluids supply fluid volume and electrolytes. 

These fluids are usually provided for:

Expanding intravascular volume

Correct an imbalance in fluids or electrolytes

Compensate for an ongoing problem that is affecting either fluid or electrolytes.

IV FLUID PROPERTIES

IV FLUID DEPLOYMENT DEVICES

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ANTI-COAGULANTS

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PROPERTIES OF ANTICOAGULANTS

Anticoagulants are drugs that help prevent the clotting (coagulation) of blood.

Antiplatelet agents are drugs that interfere with the ability of blood to clot.

Antiplatelet agents work by preventing the platelets in the blood from clumping.

Examples of antiplatelet include aspirin, dipyridamole etc.

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PROPERTIES OF ANTICOAGULANTS (contd.)

Heparin is an anticoagulant. Forms an high-affinity complex

with antithrombin.

This increases the rate of inhibition of two principle procoagulant proteases: factor Xa and thrombin.

The rapid inactivation of both the active forms of proteases prevents the subsequent conversion of fibrinogen to fibrin that is crucial for clot formation.

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BIOMATERIALS

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BIOMATERIALS

Classes of biomaterials used in medicine are Natural Materials Alloy Metals Composites Ceramics Fabrics Stainless steel

Uses for the development of mechanical heart valves pacemakers vascular grafts oxygenators heart assist systems such as total artificial hearts,

intra-aortic balloon pumps etc.

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BIOMATERIALS (HEART VALVES)

Mechanical heart valves are most commonly made from : Silicone Elastomer Prolytic carbon Cobalt Chrome based alloys Titanium

The prosthetic valves are made from Materials of biological origin.

These are Homografts obtained from human species Xenografts obtained from non-human species pig,

cow

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BIOMATERIALS (OTHER DEVICES)

Stents are typically made from inert materials like: Nickel Titanium Polyethylene Tetraphthlate Polyurethane Various acrylate compositions. Stainless steel.

Pacemakers Battery is of lithium-iodine The electrodes are made of platinum, gold,

stainless steel, or cobalt alloys.

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VASCULAR FLUID MECHANICS & CFD

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VASCULAR FLUID MECHANICS

Velocity and pressure are inversely related to the cross sectional area of blood vessels.

These parameters drop in the capillaries where the cross-sectional area is more.

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VASCULAR FLUID MECHANICS (contd.)

The Casson's model hasbeen validated for blood velocity in both large sized and small sized arteries.

The velocity of blood varies inversely with the radius of the vessel.

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COMPUTATIONAL FLUID DYNAMICS (CFD)

CFD is a powerful and versatile tool for the prediction of detailed flow patterns: Regions of stagnant Re-circulating fluid Detailed pressure variations Shear stresses in the fluid and at boundaries.

CFD enables sophisticated analysis to predict Heat transfer & mass transfer (e.g. perspiration,

dissolution) Phase change (e.g. freezing, boiling) Chemical reaction (e.g. combustion) Mechanical movement (e.g. impeller turning) Stress or deformation of a related structure.

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CFD USED FOR SIMULATING BLOOD FLOW

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COMPUTATIONAL FLUID DYNAMICS(TESTING DEVICE DESIGN)

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ARTIFICIAL HEART SYSTEMS

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ARTIFICIAL HEART FACTS

About 700,000 Americans annually die of heart failure.

100,000 Americans annually could prolong their lives with a proven, reliable mechanical heart.

An estimated 350,000 cases (i.e. 50% cases) die from sudden cardiac arrest as a result there is no time to address the patient with a cardiac assist device.

Only 2,300-2,500 cases a year that involve a patient donor.

This shortage demonstrates the need for an alternative transplantation namely Artificial Heart Transplantation.

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ARTIFICIAL HEART HISTORY

Year Scientist Event

1953 Dr. John Gibbon A Heart-lung machine.

1964 The National Heart, Lung and Blood Institute

Set a goal to design TAH by 1970.

1966 Dr. Michael DeBakey Implantation of a partial artificial heart

1967 Dr. Christiaan Barnard Human Heart Transplant.

1969 Dr. Denton Cooley Total artifical heart

1982-85 Dr. William DeVries Jarvik total artificial heart

1994 Food and Drug Administration

Approval the Left Ventricular Assist Device

2000 Texas Heart Institute Jarvik 2000

2001 Abiomed Inc AbioCor

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TOTAL ARTIFICIAL HEART (ABIOCOR:First Completely self-contained TAH)

Hydraulic pump transports hydraulic fluid from side to side.

Rotates at approximately 10000 rpm.

Valve opens and closes to control

fluid motion to the left and right.

When the fluid moves to the right, blood gets pumped to the lungs through an artificial ventricle.

When the fluid moves to the left, blood gets pumped to the rest of the body.

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A Battery pack can pump the AbioCor for 4 hours.

Battery pack is the external component.

Power to the AbioCor is achieved with an energy-transfer device called a Transcutaneous Energy Transmission (TET) system.

TOTAL ARTIFICIAL HEART (ABIOCOR) (contd.)

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TOTAL ARTIFICIAL HEART (JARVIK 7 and JARVIK 2000)

The Jarvik-7 has two pumps, much like the heart's ventricles. The ventricles are pneumatically (air) powered.

The Jarvik 2000 is an axial flow blood pump.

An analog system controller controls the pump speed (8000-12000rpm).

Audible and visual alerts notify the user of any problems.

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TOTAL ARTIFICIAL HEART (ABIOMED BVS-5000)

The ABIOMED BVS-5000 is used worldwide for temporary left, right, or biventricular (both ventricles) support in patients with potentially reversible heart failure.

It was the first heart assist device approved by the U.S. Food and Drug Administration for the support of post-cardiotomy patients (those who have developed heart failure as a result of heart surgery).

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INTRA-AORTIC BALLOON PUMP (IABP)

Simple yet effective device to increase coronary perfusion.

Polyethylene balloon (inflated with helium), mounted on a catheter.

The balloon is guided into the descending aorta, approximately 2 cm from the left subclavian artery.

At the start of diastole, the balloon inflates, augmenting coronary perfusion. At the beginning of systole, the balloon deflates.

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LEFT VENTRICULAR ASSIST DEVICES (LVAD)

LVAD are used in patients with severe heart failure when the heart is no longer capable of pumping blood.

Inserted in the chest cavity.

LVAD moves blood from the left ventricle to the aorta and back through an air driven pump.

Reduces the workload of the heart allowing the heart to recover its strength.

Currently used for short-term applications.

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COST OF THE PROCEDURE

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COST OF IMPLATATION

Complete heart replacement device can cost about $75,000.

Procedure expenses cost about $175,000.

A trial was analyzed from a costing point of view.

Three artificial hearts were studied but the first two artificial hearts and a third yet to be implanted was about $259,000 at the current rate of exchange.

It is being financed by the National Heart Research Fund.

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FUTURE ADVANCES

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FUTURE DEVELOPMENTS OF TAH

Novel mathematical models of hemolysis and blood coagulation from the viewpoint of nanoscale bio-fluid mechanics will be proposed.

The use of VFP, a treatment of multiple organ failure by the blood flow distribution is being established.

VFP Advantages  Generating the stable oscillated flow Self-priming function Excellent controllability of the liquid flow Decreasing the hemolysis by the use of jellyfish

valve

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FUTURE DEVELOPMENTS OF TAH (contd.)

Carnegie-Mellon University and the Ford Motor Company announced successful prototype testing of a new TAH.

Powered by a diesel-fueled internal combustion engine. Nicknamed the "Model H," it consists of a 4-

cylinder, 4-stroke compression-ignition engine driving a 4-chambered Teflon-coated bellows.

The engine is fed by a close-proximity high-density fuel reservoir

The engine is refueled through a dime-sized nozzle mounted just below the clavicle.

Miniaturized combustion technology was , used to avoid bulky external battery packs.

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CONCLUSION

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CONCLUSIONS

At an annual cost of $12 Billion congestive heart disease stands as the most expensive diagnosis in the United States.

Heart failure is the number one cause of death in the United States as well as worldwide.

Each year an estimated 400,000 patients are newly diagnosed with this clinical problem.

Artificial Heart Development is a multidisciplinary research effort

Ultimate aim is to improve the design of existing artificial heart devices, and develop of the next generation of implantable devices.

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ACKNOLWEDGEMENTS

We would like to express our gratitude towards Dr. Megh Goyal for reviewing this presentation

We would also like to thank all our colleagues in the Biomedical Engineering Institute for their invaluable help.

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JUST BEFORE I LEAVE……

One of the Keys to

Happiness is having a

good health and a bad memory…

-- Ingrid Bergman

                                                 

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ANY QUESTIONSANY QUESTIONS

THANK YOUTHANK YOU