The artificial heart
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Transcript of The artificial heart
ENERGY TRANSFER FOR AN ARTIFICIAL
HEART
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An artificial heart is a prosthetic device that is implanted into the body to replace the biological heart.
Artificial heart a pumping mechanism that duplicates the rate, output, and blood pressure of the natural heart; it may replace the function of a part or all of the heart.
INTRODUCTION
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ARTIFICIAL HEART
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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
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Cont…Right and left atria receive
bloodRight and left ventricles pump
bloodValves 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
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Why heart substitutes fail?
Immune response “rejects” transplant or side effects due to immune suppression
Formation of clotsDamage to red blood cellsLack of pulsatile blood flow
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ARTIFICIAL HEART HISTORY
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Artificial heart are of three types
VENTRICULAR ARTIFICIAL HEART
VENTRICULAR ASSIST DEVICE
TOTAL ARTIFICIAL HEART
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VENTRICULAR ARTIFICIAL HEART
Each pump is small enough to be
implanted into the void that was left
behind from the extraction.
The jarvik-7 design incorporates two heart pumps that are connected to a power console.
Both pumps receive power from a large
external console. The console pushes air through
the tubing.
Air enters inside the pump and is expelled
through a series of thin flexible diaphragms.
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VENTRICULAR ASSIST DEVICE
Michael has pioneered the development
of heart pumps since the early 1960s.
Ventricular assist device, invented by Dr Michael DeBakey was
implanted in 1966 at Methodist hospital in Texas.
In 1966, he performed the first successful
implantation of a ventricular assist device.
The patient's heart recovered while the VAD
took over its pumping chores.
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TOTAL ARTIFICIAL HEART
The AbioCor™ implantable replacement heart is the first completely self-contained
total artificial heart. It is the product of 30 years of research, development,
and testing conducted by ABIOMED, Inc. in order to extend and improve the lives of
patients who would otherwise die of heart failure.
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ENERGY TRANSFER Electrical circulatory assist devices use
brushless dc motor as its pump Electrical energy is transferred to these devices
transcutaneously using a transcutaneous transformer
Transcutaneous transformer has large leakage inductance which reduce its efficiency
Dc-dc converter employing secondary side resonance can be employed to alleviate this problem but the transfer gain of voltage varies widely with coupling coefficient
Converter employing compensation of leakage inductance on both sides of the transformer offers stable gain and high efficiency
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PROPOSED ENERGY TRANSFERENCE SCHEME
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Determination of Control region Gv curve is divided into 3 regions: low
frequency, middle frequency and high frequency regions
Region II provides maximum transfer gain but is very sensitive to changes in load and coupling coefficient, hence not used
Region I and III can control output voltage
Region III is desirable because the unity gain frequencies is much less sensitive than for region I
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System Design
Output requirements: V0 = 24V Iomax =2.0A I0min =0.5A Size, geometry and core material of the
transformer and range of air gap and misalignment between them are already defined
For transformer windings the same cores used in series converter are used
System Design Transformer Core: Ferroxcube Pot Core 6656 3C8 Ferrite OD=2.6in Thickness=1.1in Air gap=10-20mm Misalignment=0-10mm Region III of gain characteristics is selected
for control Low value of Q is selected to reduce
sensitivity if variation Compensating resonant frequency is chosen at
120kHz
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The AbioCor, along with other
components is surgically
implanted; it is designed to fit
within chest and abdomen.
ABIOCOR SYSTEM
• The AbioCor System consists of the following
implanted components: Replacement Heart Implanted TET Implanted Controller Implanted Battery
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The thoracic unit weighs slightly more than two pounds (0.9 kg) and is
about the same size and shape of a natural heart.
It is made of titanium, and Angioflex, a polyurethane plastic.
REPLACEMENT HEART
The thoracic unit is implanted in the chest, and connects
to the right and left atria, the aorta, and the pulmonary
artery.
The thoracic unit contains two hydraulic motors; one
keeps the blood pumping from each ventricle (blood
pump), and the other operates the motion of the four heart
valves.
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IMPLANTED TRANSCUTANEOUS ENERGY
TRANSMISSION (TET)
The implanted TET is an electric coil that provides
all of the AbioCor System’s internal devices with
electrical energy.
It is connected to the thoracic unit, the implanted
controller, and the implanted battery.
The implanted TET is located on the upper-left area
of the chest (opposite of the artificial heart).
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The job of the implanted controller is to
oversee the internal components of the
AbioCor System.
The implanted controller is also able to
manage the artificial heart’s cardiac output
rate to make sure that the artificial heat
generates the necessary blood flow.
IMPLANTED CONTROLLERThe implanted controller is a small automatic computer located in
the abdomen of the patient’s body.
It is secured in a titanium case and connects to all internal
components.
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The implanted battery is placed in the abdomen,
opposite from the implanted Controller.
It is implanted when the implanted controller and
the artificial heart are placed in the patient’s body.
The implanted battery is kept in a titanium case, it
receives energy from the external TET.
It is connected to all other internal components.
If the patient were to separate himself from the
external TET and battery pack (such as to take a
shower), the implanted battery would provide
energy for 30 - 40 minutes.
IMPLANTED BATTERY
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External Components:
TRANSCUTANEOUS ENERGY
TRANSMISSION (TET)
PATIENT-CARRIED
ELECTRONICS.
PCE BATTERY BAG
PCE BATTERIES
PCE CONTROL MODULE
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TRANSCUTANEOUS ENERGY TRANSMISSION (TET)
The external TET is placed directly over the location of the internal
TET to transfer energy through the skin.
If the patient is stationary and is near a power outlet, his source for
energy may be the console.If the patient is mobile and has
no intentions of remaining in
the same location for a long
period of time, he may use the
PCE as a power source.
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PATIENT-CARRIED ELECTRONICS
The patient using the AbioCor System is not
forced to stay in bed hooked up to the
system’s console;
He is also given the option to move around
and not have to depend on a power outlet to
power the system’s components.
If the patient chooses to be mobile(movable)
he may use the Patient-Carried Electronics
(PCE) by plugging the external TET into the
PCE’s control module.
PCE BATTERY BAG
PCE Battery Bag weighs : 10 pounds.
Carried by using : An attached shoulder strap (Abiomed).
Inside of the bag contains : Four batteries, plastic cardholders.
Outside of the bag contains : PCE control module.
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PCE BATTERIESEach pair of PCE Batteries supplies the AbioCor’s internal system with
power for about one hour (Abiomed).
The battery bag can carry two pairs of PCE batteries.
The internal system may be supplied with power for about two hours .
Additionally, since the PCE batteries don’t last very long, they must be
changed several times a day so patient can take extra batteries if necessary.
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PCE CONTROL MODULE
The PCE control module is to be placed in one
of the pockets of the PCE battery bag.
It is connected to the batteries by a battery cable
and is also connected to the external TET.
If a problem occurs within one of the internal
devices, the control module immediately notifies
the patient.
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To maintain operation, the AbioCor System
must first have a source of power depending
on whether or not the patient is mobile.
This power source will either be the console or
the PCE control module.
If the power source detects a problem, an
alarm light or an alarm sound notifies the
patient.
Otherwise, if no problems are detected the
AbioCor System follows a cyclic function and
continues to operate.
FUNCTION
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COST OF IMPLANTATION
Complete heart replacement device can
cost about $75,000.
Procedure expenses cost about
$175,000.
It is financed by the national heart
research fund.
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There are many obstacles to overcome before
any TAH is widely accepted.
The AbioCor System consists of a set of
internal components and external components.
The internal and external TETs work together
to convert this energy into usable energy for all
internal components.
CONCLUSION
• All of these provide power for the artificial
heart and components keep the artificial heart
pumping blood and keep sending that blood
throughout the patient’s body.
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“ARTIFICIAL HEART IS NOT A
BRIDGE TO
TRANSPLANTATION BUT A LIFE
EXTENDING DEVICE”
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REFERENCESAbiomed. Product details. http://www.abiomed.com/products/heart_replacement/product_details.cfm
Bonsor, Kevin. How Artificial Hearts Work. http://science.howstuffworks.com/artificial-heart.htm
Brain, Marshall. How Hydraulic Machines Work.http://science.howstuffworks.com/hydraulic.htm
Cho, B.H., Gyu Bum Joun. “An energy transmission system for an artificial heart using leakage inductance compensation of transcutaneous transformer”. IEEE. Nov. 1998http://ieeexplore.ieee.org/xpl/abs_free.jsp?arNumber=728328
Factmonster. heart, artificial. <http://www.factmonster.com/ce6/sci/A0823119.html>
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