Description:

An artificial heart is a mechanical device used to replace a real heart. It keep the blood circulating in the body if it gets damaged or diseased. It was created in 1935 by Alexis Carrel and Charles Lindbergh. It was first inserted into a dog in 1957. The Jarvik-7 was the first one to be surgically implanted in a human being in 1982. The mans name was Barney Clark and he lived for 112 days. Before the Jarvik-7 was discontinued due to complications, it since has been improved and is now called the CardioWest heart.
The CardioWest has tubes that, through holes in the abdomen, run from inside the chest to an outside power source. The AbioCor implantable replacement heart is the first self-contained artificial heart and its expected to double a patients life expectancy. It connects to the left atrium, right atrium, aorta, and pulmonary artery. Unlike a real heart, it must alternate sending blood to the body and to the lungs rather than doing it at the same time and is able to pump over 10 liters per minute.

The Hydraulic Pump:
The various components of the system of the AbioCor System are:
  • Hydraulic pump - The basic idea with this device is similar to the hydraulic pumps used in heavy equipment. Force that is applied at one point is transmitted to another point using an incompressible fluid. A gear inside the pump spins at 10,000 revolutions per minute (rpm) to create pressure.
  • Porting valve - This valve opens and closes to let the hydraulic fluid flow from one side of the artificial heart to the other. 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.
  • Wireless energy-transfer system - Also called the Transcutaneous Energy Transfer (TET), this system consists of two coils, one internal and one external, that transmit power via magnetic force from an external battery across the skin without piercing the surface. The internal coil receives the power and sends it to the internal battery and controller device.
  • Internal battery - A rechargeable battery is implanted inside the patient's abdomen. This gives a patient 30 to 40 minutes to perform certain activities, such as showering, while disconnected from the main battery pack.
  • External battery - This battery is worn on a Velcro-belt pack around the patient's waist. Each rechargeable battery offers about four to five hours of power.
  • Controller - This small electronic device is implanted in the patient's abdominal wall. It monitors and controls the pumping speed of the heart.
The entire system weighs about 2 pounds (0.9 kg) and is composed of titanium and plastic.

Procedure
The procedure was developed by University of Louisville surgeon, Robert Dowling:
  1. An energy-transfer coil is implanted in the abdomen by the surgeon.
  2. The patient is placed on a heart-lung machine, once the breast bone is opened.
  3. The left and right ventricle is remove from the native heart. The rest of the parts of the heart is left in place and this procedure takes about two to three hours.
  4. Atrial cuffs are sewn to the native heart's right and left atria.
  5. A plastic model is placed in the chest to determine the proper placement and fit of the heart in the patient.
  6. Grafts are cut to an appropriate length and sewn to the aorta and pulmonary artery.
  7. The AbioCor is placed in the chest. Surgeons use "quick connects" -- sort of like little snaps -- to connect the heart to the pulmonary artery, aorta and left and right atria.
  8. All of the air in the device is removed.
  9. The patient is taken off the heart-lung machine.
  10. The surgical team ensures that the heart is working properly.

Application:

Artificial hearts are used to replace a damaged or diseased heart. They are normally given to a person when the person is awaiting a transplant.
The main component is the hydraulic pump which is itself made up of multiple components:
  • The porting valve opens and closes to allow the hydraulic fluid to move back and forth inside the heart causing blood to pump into either the body or the lungs.
  • The wireless energy transfer system consists of an external and internal coil which uses magnetic force to transfer energy from the external battery across the skin to the internal battery and controller.
  • The internal battery is a rechargeable battery in the patients abdomen which can run for 30 to 40 minutes on its own without being connected to the external battery pack.
  • The external battery is worn around the patients waist and has 4-5 hours of power.
  • The controller, which is in the abdomen wall, controls the pumping speed of the heart.
The surgery itself takes 7 hours and involves the patient being hooked up to a heart-lung machine. It is an extremely delicate operation and a large amount of medical personnel are on hand during the procedure.

Normal Heart and CardioWest Total Artificial Heart
cardiowest_tah.jpg
A. shows the normal structure and location of heart. B. shows a CardioWest heart-tubes exit the body and connects to a machine that powers and contols how it works.














Normal Heart and AbioCor Total Artificial Heart
abiocor_tah.jpg
A. shows the normal structure and location of heart. B. shows an AbioCor heart and the internal devices that control how it works.


Related Terminology:

Heart Transplant

Sources:

http://inventors.about.com/library/inventors/blartificialheart.htm
http://health.howstuffworks.com/medicine/modern/artificial-heart2.htm
http://science.howstuffworks.com/innovation/everyday-innovations/artificial-heart1.htm
http://www.nhlbi.nih.gov/health/health-topics/topics/tah/

Graphics:

external image artificial-heart-abiocor-hand.jpg
total-artificial-heart-and-freedom-driver.jpg