artificial heart

(medicine) An endoprosthetic device used to replace or assist the heart.

For more information on artificial heart, visit Britannica.com.

Background

A natural heart has two pumps, each with two chambers. The right atrium pumps oxygen-depleted blood from the body into the right ventricle, which pumps it to the lungs. The left atrium sends aerated blood from the lungs into the left ventricle, which pumps it out to the body. With each heart beat, the two atria contract together, followed by the large ventricles.

Congestive heart failure, which is the steadily declining ability of the heart to pump blood, is one of the leading causes of death. This disease is caused by sudden damage from heart attacks, deterioration from viral infections, valve malfunctions, high blood pressure and other problems. According to the American Heart Association, an estimated five million Americans are living with heart failure and over 400,000 new cases are diagnosed every year. About 50% of all patients die within five years. Heart disease cost the United States health industry about $95 billion in 1998.

Though medication and surgical techniques can help control symptoms, the only cure for heart failure is an organ transplant. In 1998, around 7,700 Americans were on the national heart transplant list but only 30% received transplants. Artificial hearts and pump-assist devices have thus been developed as potential alternatives.

An artificial heart maintains the heart's blood circulation and oxygenation for varying periods of time. The ideal artificial heart must beat 100,000 times every 24 hours without requiring either lubrication nor maintenance and must have a constant power source. It must also pump faster or slower depending on the activity of the patient without causing either infection or blood clots.

The two major types of artificial hearts are the heart-lung machine and the mechanical heart. The first type consists of an oxygenator and a pump and is mainly used to keep blood flowing while the heart is operated on. This machine can only operate for a few hours since the blood becomes damaged after longer times.

A mechanical heart is designed to reduce the total work load of a heart that can no longer work at its normal capacity. These hearts consist of equipment that pulses the blood between heart beats or use an artificial auxiliary ventricle (left ventricle assist device, LVAD) that pumps a portion of the normal cardiac output. Because such devices usually result in complications to the patient, they have generally been used as a temporary replacement until natural hearts can be obtained for transplantation. Worldwide about 4,000 LVADs have been implanted. The market for these devices is estimated at $12 billion per year in the United States.

History

Since the late nineteenth century, scientists have tried to develop a mechanical device that could restore oxygen to the blood and remove excessive carbon dioxide, as well as a pump to temporarily supplant heart action. It took almost 100 years before the first successful heart-lung machine was used on a human being by John H. Gibbon Jr. in 1953. Four years later the first artificial heart (made from plastic) in the western world was implanted inside a dog. The National Heart Institute established the artificial heart program in 1964, leading to the first total artificial heart for human use implanted in 1969.

The emphasis shifted to left ventricular assist systems and blood compatible materials in 1970. During that same year, a LVAD was used successfully. However, blood pump development continued and devices became smaller, lighter, more acceptable, and clinically successful. A number of polyurethane and plastic pumps of longlife time were also developed. During the 1980s, the Food and Drug Administration (FDA) imposed more restrictive rules to the Medical Devices Standards Act, leading to higher development costs. Many research groups had to drop out, with only a few remaining today.

Perhaps the most famous scientist is Dr. Robert Jarvik, who invented an artificial heart called the Jarvik-7. This device, made from aluminum and plastic, replaced the two lower chambers of the natural heart and used two rubber diaphragms for the pumping action. An external compressor the size of a refrigerator kept the artificial heart beating. Barney Clark was the first patient to receive this heart. He survived 112 days before physical complications caused by the implant took his life. In 1986, William Schroeder became the second Jarvik-7 recipient, surviving for about 20 months.

The medical community realized that a completely implantable heart could avoid the mobility and infection problems caused by the Jarvik-7. In 1988, the National Institutes of Health began funding development of such hearts and was supporting such a program in 1991 totaling $6 million. Three years later, an electric and battery-powered implantable LVAD became available. In 1999, Charlie Chappis became the first patient ever released from a hospital with such a device. Other artificial hearts of various designs are currently being tested.

Raw Materials

An artificial heart or LVAD is made out of metal, plastic, ceramic, and animal parts. A titanium-aluminum-vanadium alloy is used for the pump and other metal parts because it is biocompatible and has suitable structural properties. The titanium parts are cast at a specialized titanium processor. Except for blood-contacting surfaces, the titanium is machined to a specific finish. Blood-contacting surfaces receive a special coating of titanium microspheres that bond permanently to the surface. With this coating, blood cells adhere to the surface, creating a living lining.

A blood-contacting diaphragm within the pump is made from a special type of polyurethane that is also textured to provide blood cell adherence. Two tubular grafts are made from polyester (which are used to attach the device to the aorta) and the valves are actual heart valves removed from a pig. Other parts that make up the motor are made from titanium or other metals and ceramics.

Design

There are several critical issues when designing a LVAD. Fluid dynamics of the blood flow must be understood so that enough blood is pumped and no blood clots are created. Materials must be chosen that are biocompatible; otherwise the pump could fail. The efficiency of the motor must be optimized so that minimal heat is generated. Because of possible rejection, the total volume and surface area of the entire device should be kept as small as possible. A typical LVAD weighs around 2.4 lb (1,200 gm) and has a volume of 1.4 pints (660 ml).

The Manufacturing Process

• 1 Most of the components are made to custom specifications by third party manufacturers, including machine shops and printed circuit board manufacturers. The porcine valves are sewn inside the grafts with sutures at a medical device firm that specializes in heart valves.

  Once all components are obtained, the LVAD system is assembled and tested, to ensure that each device meets all specifications. Once tested, the LVAD can be sterilized and packaged for shipment.

Forming the polyurethane parts

• Some artificial heart manufacturers make their own polyurethane parts. One process uses a proprietary liquid solution that is poured on a ceramic mandrel layer by layer. Each layer is heated and dried until the desired thickness is reached. The part is then removed from the mandrel and inspected. Otherwise, a third party manufacturer uses an injection molding or vacuum molding process combined with radio frequency welding.

Assembly

• Each artificial heart takes several days to put together and test. The assembly process is performed in a clean room to avoid contamination. Each artificial heart consists of up to 50 components that are put together using special adhesives. These adhesives require curing at high temperatures. Several assembly operations happen in parallel, including the assembly of the motor housing and components, the assembly of the percutaneous tube and the attachment of the pusher plates to the polyurethane diaphragm. These subsystems are individually inspected, then final assembly of the complete system occurs. The grafts are assembled separately and attached during operation.

Testing

• After assembly is completed, each device is tested using special equipment that simulates pressures in the body. All electronic components are tested with electronic test equipment to ensure the proper function of all circuitry.

Sterilization/packaging

• After the artificial heart is tested and passes, it is sent to an outside service for sterilization. Each device is sealed in plastic trays and returned to the heart manufacturer. It is then packaged in custom suitcases to protect it from contamination and prevent damage.

Quality Control

Most components have already passed inspection before they arrive at the heart manufacturer. Some components are still inspected dimensionally since they require tight tolerances—on the order of millionths of an inch, which requires special measuring tools. To meet FDA regulations, every component (including adhesives) used in the process is controlled by lot and serial number so that tracking problems is possible.

Byproducts/Waste

Scrap titanium is recovered and recycled after remelting and recasting. Otherwise, little waste is produced since most components have passed inspection before leaving the various manufacturers. Other defective parts are discarded. Once a device has been used by a patient, it is sent back to the heart manufacturer for analysis to improve the design.

The Future

Within the next decade, a number of new devices will come on the market. Pennsylvania State University researchers are developing an electromechanical heart powered by radio-frequency energy that is transmitted through the skin. A motor drives push plates, which alternate in pressing against plastic blood-filled sacs to simulate pumping. Patients carry a battery pack during the day and sleep with the device plugged in to an electrical outlet. This artificial heart will be tested in humans by 2001.

Several research groups are developing pumps that circulate blood continuously, rather than using a pumping action, since these pumps are smaller and more efficient. In Australia, Micromedical Industries Limited is developing a continuous-flow rotary blood pump, which is expected to be implanted in a human by 2001. The Ohio State University's cardiology department is developing a plastic pump the size of a hockey puck that is self regulating. This pump is implanted in patients for several weeks until their own heart recovers.

Thermo Cardiosystems, Inc. is also working on a LVAD with a continuous flow rotary pump), expected to be implanted sometime in 2000, and a LVAD with a continuous flow centrifugal pump. The latter is still in an early development phase, but is planned to be the world's first bearingless pump, meaning that it won't have any parts that wear. This is accomplished by magnetically suspending the rotor of the pump. Both these devices will be available with transcutaneous energy transfer, meaning that the devices will be fully implantable.

With fewer donor hearts becoming available, others are also developing an artificial heart that is a permanent replacement. These replacements may be in the form of a left ventricle assist device or a total artificial heart, depending on the patient's physical condition. LVADs are being developed by inventor Robert Jarvik and renowned heart surgeon Michael DeBakey. Total artificial hearts are being jointly developed by the Texas Heart Institute and Abiomed, Inc. in Massachusetts. In Japan, researchers are developing total artificial hearts based on a silicone ball valve system and a centrifugal pump with a bearing system made from alumina ceramic and polyethylene components.

Alternatives to artificial hearts and heart-assist pumps are also under development. For instance, a special clamp has been invented that changes the shape of a diseased heart, which is expected to improve the pumping efficiency by up to 30%. Such a device requires minimal invasive surgery to implant.

Where to Learn More

Periodicals

Bonfield, Tim. "Device to Help Hearts." Cincinnati Enquirer (November 7, 1999).

Castor, Tasha. "Ohio State University Cardiology Unit Set to Try Heart Pump." The Lantern (May 6, 1999).

"Electric Hearts by 2005." Popular Mechanics (March 1997).

Gugliotta, Guy. "Upbeat on Man-Made Hearts: Improved Devices Save Those Too III for Transplant." The Washington Post (June 28, 1999): AOl.

Guy, T. Sloane. "Evolution and Current Status of the Total Artificial Heart: The Search Continues." ASAIO Journal (January-February 1998): 28-33.

Hall, Celia. "Thumb-Sized Pump Can Cut Heart Deaths." The Daily Telegraph (September 13, 1999): 11.

Hesman, Tina. "Pump Brings New Expectations for Artificial Heart." Omaha World-Herald (December 12, 1999).

Hopkins, Elaine. "Device Lets Heart Patient Await Transplant at Home." Journal Star (November 30, 1999).

Kinney, David. "Effective Artificial Heart Seems Within Reach." The Los Angeles Times (January 23, 2000).

Kolff, William. "Early Years of Artificial Organs at the Cleveland Clinic: Part II: Open Heart Surgery and Artificial Hearts." ASAIO Journal (May-June 1998): 123-128.

Kolff, William. "The Need for Easier Manufacturing of Artificial Hearts and Assist Devices and How This Need Can Be Met by the Vacuum Molding Technique." ASAIO Journal (January-February 1998): 12-27.

Kunzig, Robert. "The Beat Goes On." Discover (January 2000): 33-34.

M2 Communications. "Successful Blood Compatibility Tests for Micromedical's Artificial Heart." M2 PressWIRE (March 26, 1999).

Phillips, Winfred. "The Artificial Heart: History and Current Status." Journal of Biomechanical Engineering (November 1993): 555-557.

Takami, Y. et al. "Current Progress in the Development of a Totally Implantable Gyro Centrifugal Artificial Heart." ASAIO Journal (May-June 1998): 207-211.

Wilson, Steve. "A Life and Death Race Against Time. " Arizona Republic (November 14, 1999).

Yambe, T. et al. "Development of Total Artificial Heart with Economical and Durability Advantages." The International Journal of Artificial Organs (1998): 279-284.

Other

"Progress on Development of an Artificial Heart." http://www.uts.edu.au/new/archives/l999/February/02.html (December 29,2000).

[Article by: Laurel M. Sheppard]

Since the 1960s there have been many attempts to develop implantable pumps to replace the function of the heart. These were initially evaluated in animals. Only in the past few years have the newer designs, refined in the light of experimental findings in animal trials, been used with reasonable success in humans. Improved materials as well as advances in electronics and mechanical engineering have also played a major part in making the artificial heart sufficiently safe and effective to allow limited clinical application.

In principle, the device consists of a rigid chamber, made of an inert material such as titanium, usually of hemispherical shape and about 7-8 cm in diameter, within which there is a moving polyurethane diaphragm which evacuates the contained blood. An inlet and an outlet valve ensure flow in one direction. Early models used an external pump to pneumatically displace the moving diaphragm. Recent designs have miniaturized electrical motors activating a pusher plate within the device, but connected to externally carried batteries by wire, or by a transcutaneous electrical energy transfer system. As the devices are not linked to any of the normal influences in the body which naturally control the output of the heart, there have to be control systems which modify the artificial pump's output and regulate the pressure of the blood flowing into the device.

Most causes of heart failure, for which use of an artificial device might be contemplated, affect the left ventricular pumping chamber. It is therefore possible to use a mechanical pump which takes its input of blood from the diseased left ventricle and returns the blood at appropriate pressure to the aorta — thus acting as a left ventricular assist device. It is this form of device which is presently showing most clinical success and has widest application.

For patients with both left and right ventricular failure, devices are available which have two parallel pumping chambers. This device is a true ‘artificial heart’, and is a mechanical alternative to a heart transplant.

The problems associated with artificial devices used to replace the heart are considerable. Clotting of blood within the device is a risk. Clots can immobilize the artificial valves and interfere with the pump itself, or can detach from the device to travel in the bloodstream. This results in clinical effects which depend on where the clot goes. If a clot enters the circulation of the brain the result is often a stroke. Anticoagulant drugs are required to minimize this risk, and anticoagulation itself carries risks of bleeding. Also, there is the risk of infection developing in the device; mechanical devices are liable to damage the blood, causing rupture of red cells and a risk of kidney damage due to the released haemoglobin from the red cells; and there is a need for regular changes of battery power source.

At present left heart assist devices will allow relatively normal life for many months, reversing many of the adverse effects on the body of long-standing heart failure. Most clinical use has been as a ‘bridge to transplant’, enabling ill patients to survive until a suitable heart becomes available for transplantation. Occasionally, use of a left heart assist device has been temporary, where the heart has been affected by a condition which is recoverable.

At present, the technology of artificial hearts is advancing rapidly, but the devices currently in use are not as satisfactory as the transplanted human heart.

— D. J. Wheatley

See also heart failure; prostheses.

A mechanical device that acts to pump blood to and from the body tissues during repair of the heart.

"Barney Clark" redirects here. For the English actor, see Barney Clark (actor).

The CardioWest temporary Total Artificial Heart

An artificial heart displayed at the London science museum

An artificial heart is a mechanical device that is implanted into the body to replace the biological heart.

The term "artificial hearts" has often inaccurately been used to describe ventricular assist devices (VADs), which are pumps that assist the heart but do not replace it.

An artificial heart is also distinct from a cardiopulmonary bypass machine (CPB), which is an external device used to provide the functions of both the heart and lungs. CPBs are only used for a few hours at a time, most commonly during heart surgery.

Contents 1 FDA approved artificial hearts 2 Origins 3 Early development 3.1 Early designs of total artificial hearts 3.2 First clinical implantation of a total artificial heart 3.3 First clinical applications of a permanent pneumatic total artificial heart 3.4 The development of permanent, implantable, electrically powered artificial hearts 3.5 First clinical application of an intrathoracic pump 3.6 First clinical application of a paracorporeal pump 4 Recent developments 4.1 Total artificial heart 5 Heart assist devices 6 References 7 External links

FDA approved artificial hearts

CardioWest temporary Total Artificial Heart

The CardioWest temporary Total Artificial Heart (TAH-t) was the first FDA-approved Total Artificial Heart. It received FDA approval on October 15, 2004, following a 10-year pivotal clinical study.^[1]

Originally designed as a permanent replacement heart, it is currently approved as a bridge to human heart transplant for patients dying because both sides of their hearts are failing (irreversible end stage biventricular failure).^[1] There have been more than 800 implants of the CardioWest artificial heart, accounting for more than 170 patient years of life on this device.^[2]

In the 10-year pivotal clinical study of the CardioWest artificial heart, 79% of patients receiving the artificial heart survived to transplant (New England Journal of Medicine 2004; 351: 859-867).^[3] This is the highest bridge-to-transplant rate for any heart device in the world.^[2] (See FDA Summary of Safety and Effectiveness.)

AbioCor Replacement Heart

Unlike the CardioWest TAH, the AbioCor Replacement Heart by Abiomed is fully implantable, meaning that no wires or tubes penetrate the skin, and, therefore, there is less risk of infection.

The AbioCor is approved for use in severe biventricular end-stage heart disease patients who are not eligible for heart transplant and have no other viable treatment options.^[4] To date, 15 patients have been implanted with the AbioCor, with one patient living for 512 days with the AbioCor.

The Abiocor received FDA approval under a Humanitarian Device Exemption (HDE) on September 5, 2006.^[5] The first implant of the AbioCor since receiving FDA approval in 2006 took place on June 24, 2009, at Robert Wood Johnson University Hospital, New Jersey.^[6] This patient later passed away on August 23, 2009^[7]. (See FDA Summary of Safety and Probable Benefit.)

Origins

A synthetic replacement for the heart remains one of the long-sought holy grails of modern medicine. The obvious benefit of a functional artificial heart would be to lower the need for heart transplants, because the demand for organs always greatly exceeds supply.

Although the heart is conceptually simple (basically a muscle that functions as a pump), it embodies subtleties that defy straightforward emulation with synthetic materials and power supplies. Consequences of these issues include severe foreign-body rejection and external batteries that limit patient mobility. These complications limited the lifespan of early human recipients to hours or days.

Early development

A heart-lung machine was used in 1953 during a successful open heart surgery. Dr. John Heysham Gibbon, the inventor of the machine, performed the operation and developed the heart-lung substitute himself.

On July 3, 1952, 41-year-old Henry Opitek, suffering from shortness of breath, made medical history at Harper University Hospital at Wayne State University in Michigan. The Dodrill-GMR heart machine, considered to be the first operational mechanical heart, was successfully used while performing heart surgery.^[8][9]

Dr. Forest Dewey Dodrill used the machine in 1952 to bypass Henry Opitek's left ventricle for 50 minutes while he opened the patient's left atrium and worked to repair the mitral valve. In Dr. Dodrill's post-operative report, he notes, "To our knowledge, this is the first instance of survival of a patient when a mechanical heart mechanism was used to take over the complete body function of maintaining the blood supply of the body while the heart was open and operated on."^[10]

The scientific interest for the development of a solution for heart disease developed in different research groups worldwide.

Early designs of total artificial hearts

In 1949, a precursor to the modern artificial heart pump was built by Dres. William Sewell and William Glenn of the Yale School of Medicine using an Erector Set, assorted odds and ends, and dime-store toys. The external pump successfully bypassed the heart of a dog for more than an hour.^[11]

On December 12, 1957, Dr. Willem Kolff, the world's most prolific inventor of artificial organs, implanted an artificial heart into a dog at Cleveland Clinic. The dog lived for 90 minutes.

In 1958, Domingo Liotta initiated the studies of TAH replacement at Lyon, France, and in 1959-60 at the National University of Cordoba, Argentina. He presented his work at the meeting of the American Society for Artificial Internal Organs held in Atlantic City in March 1961. At that meeting, Dr. Liotta described the implantation of three types of orthotopic (inside the pericardial sac) TAHs in dogs, each of which used a different source of external energy: an implantable electric motor, an implantable rotating pump with an external electric motor, and a pneumatic pump.^[12][13]

In 1964, the National Institutes of Health started the Artificial Heart Program, with the goal of putting a man-made organ into a human by the end of the decade.^[14]

In 1967, Dr. Kolff left Cleveland Clinic to start the Division of Artificial Organs at the University of Utah and pursue his work on the artificial heart.
- In 1973, a calf named Tony survived for 30 days on an early Kolff heart.
- In 1975, a bull named Burk survived 90 days on the artificial heart.
- In 1976, a calf named Abebe lived for 184 days on the Jarvik 5 artificial heart.
- In 1981, a calf named Alfred Lord Tennyson lived for 268 days on the Jarvik 5.

Over the years, more than 200 physicians, engineers, students and faculty developed, tested and improved Dr. Kolff's artificial heart. To help manage his many endeavors, Dr. Kolff assigned project managers. Each project was named after its manager. Graduate student Robert Jarvik was the project manager for the artificial heart, which was subsequently renamed the Jarvik 7.

In 1981, Dr. William DeVries submitted a request to the FDA to implant the Jarvik 7 into a human being. On December 2, 1982, Dr. Kolff's 35 years of dedication culminated in the first implant of the Jarvik 7 artificial heart into Dr. Barney Clark. Clark was hours from death prior to the surgery. He lived for 112 days with the artificial heart.

On February 11, 2009, Dr. Kolff died at the age of 97 in Philadelphia. See press release.

First clinical implantation of a total artificial heart

On the morning of April 4, 1969, Domingo Liotta and Denton A. Cooley replaced a dying man's heart with a mechanical heart inside the chest at the Texas Heart Institute in Houston as a bridge for a transplant. The patient woke up and recovered well. After 64 hours, the pneumatic-powered artificial heart was removed and replaced by a donor heart. Replacing the artificial heart proved to be a bad decision, however; thirty-two hours after transplantation, the patient died of what was later proved to be an acute pulmonary infection, extended to both lungs, caused by fungi, most likely caused by an immunosuppressive-drug complication. If they had left the artificial heart in place, the patient may have lived longer.^[15]

The original prototype of Liotta-Cooley artificial heart used in this historic operation is prominently displayed in The Smithsonian Museum "Treasures of American History" exhibit in Washington, D.C.

First clinical applications of a permanent pneumatic total artificial heart

The eighty-fifth clinical use of an artificial heart designed for permanent implantation rather than a bridge to transplant occurred in 1982 at the University of Utah. Artificial kidney pioneer Dr. Willem Johan Kolff started the Utah artificial organs program in 1967.^[16] There, physician-engineer Dr. Clifford Kwan-Gett invented two components of an integrated pneumatic artificial heart system: a ventricle with hemispherical diaphragms that did not crush red blood cells (a problem with previous artificial hearts) and an external heart driver that inherently regulated blood flow without needing complex control systems.^[17] Independently, ventriloquist Paul Winchell designed and patented a similarly shaped ventricle and donated the patent to the Utah program.^[18] Throughout the 1970s and early 1980s, veterinarian Dr. Donald Olsen led a series of calf experiments that refined the artificial heart and its surgical care. During that time, as a student at the University of Utah, Dr. Robert Jarvik combined several modifications: an ovoid shape to fit inside the human chest, a more blood-compatible polyurethane developed by biomedical engineer Dr. Donald Lyman, and a fabrication method by Kwan-Gett that made the inside of the ventricles smooth and seamless to reduce dangerous stroke-causing blood clots.^[19] On December 2, 1982, Dr. William DeVries implanted the artificial heart into retired dentist Dr. Barney Bailey Clark (born January 21, 1921), who survived 112 days with the device, dying on March 23, 1983. Bill Schroeder became the second recipient and lived for a record 620 days.

Contrary to popular belief and erroneous articles in several periodicals, the Jarvik heart was not banned for permanent use. Today, the modern version of the Jarvik 7 is known as the SynCardia temporary CardioWest Total Artificial Heart. It has been implanted in more than 800 people as a bridge to transplantation.

The development of permanent, implantable, electrically powered artificial hearts

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In the mid-1980s, artificial hearts were powered by dishwasher-sized pneumatic power sources whose lineage went back to Alpha-Laval milking machines. Moreover, two sizable catheters had to cross the body wall to carry the pneumatic pulses to the implanted heart, greatly increasing the risk of infection. To speed development of a new generation of technologies, the National Heart, Lung, and Blood Institute opened a competition for implantable electrically powered artificial hearts. Three groups received funding: Cleveland Clinic in Cleveland, Ohio; the College of Medicine of Pennsylvania State University (Penn State Hershey Medical Center) in Hershey, Pennsylvania; and Abiomed, Inc. of Danvers, Massachusetts. Despite considerable progress, the Cleveland program was discontinued after the first five years.

Polymeric trileaflet valves ensure unidirectional blood flow with a low pressure gradient and good longevity. State-of-the-art transcutaneous energy transfer eliminates the need for electric wires crossing the chest wall.

The first AbioCor to be surgically implanted in a patient was on July 3, 2001.^[20] The AbioCor is made of titanium and plastic with a weight of two pounds, and its internal battery can be recharged with a transduction device that sends power through the skin.^[20] The internal battery lasts for a half hour, and a wearable external battery pack lasts for four hours.^[21] The FDA announced on September 5, 2006, that the AbioCor could be implanted for humanitarian uses after the device had been tested on 15 patients.^[22] It is intended for critically ill patients who can not receive a heart transplant.^[22] Some limitations of the current AbioCor are that its size makes it suitable for only about 50% of the male population, and its useful life is only 1–2 years.^[23] By combining its valved ventricles with the control technology and roller screw developed at Penn State, Abiomed has designed a smaller, more stable heart, the AbioCor II. This pump, which should be implantable in most men and 50% of women with a life span of up to five years,^[23] had animal trials in 2005, and the company hopes to get FDA approval for human use in 2008.^[24]

First clinical application of an intrathoracic pump

On the evening of July 19, 1963, E. Stanley Crawford and Domingo Liotta implanted the first clinical LVAD at the Methodist Hospital in Houston, Texas, in a patient who had a cardiac arrest after surgery. The patient survived for four days under mechanical support but did not recover from the complications of the cardiac arrest; finally, the pump was discontinued, and the patient died.

First clinical application of a paracorporeal pump

On the afternoon of April 21, 1966, Michael DeBakey and Liotta implanted the first clinical LVAD in a paracorporeal position (where the external pump rests at the side of the patient) at the Methodist Hospital in Houston, in a patient experiencing cardiogenic shock after heart surgery. The patient developed neurological and pulmonary complications and died after few days of LVAD mechanical support. In October 1966, DeBakey and Liotta implanted the paracorporeal Liotta-DeBakey LVAD in a new patient who recovered well and was discharged from the hospital after 10 days of mechanical support, thus constituting the first successful use of an LVAD for postcardiotomy shock.

Recent developments

In August 2006, an artificial heart was implanted into a 15-year-old girl at the Stollery Children's Hospital in Edmonton, Alberta. It was intended to act as a temporary fixture until a donor heart could be found. Instead, the artificial heart (called a Berlin Heart) allowed for natural processes to occur and her heart healed on its own. After 146 days, the Berlin Heart was removed, and the girl's heart was able to function properly on its own.^[25]

With increased understanding of the heart and continuing improvements in prosthetics engineering, computer science, electronics, battery technology, and fuel cells, a practical artificial heart may become a reality.

Total artificial heart

On October 27, 2008, French professor and leading heart transplant specialist Alain F. Carpentier announced that a fully implantable artificial heart will be ready for clinical trial by 2011 and for alternative transplant in 2013. It was developed and will be manufactured by him, Biomedical firm Carmat, and venture capital firm Truffle. The prototype uses electronic sensors and is made from chemically treated animal tissues, called "biomaterials", or a "pseudo-skin" of biosynthetic, microporous materials. Another US team with a prototype called 2005 MagScrew Total Artificial Heart, including Japan and South Korea researchers are racing to produce similar projects.^[26][27][28]

Heart assist devices

Main article: ventricular assist device

Patients who have some remaining heart function but who can no longer live normally may be candidates for ventricular assist devices (VAD), which do not replace the human heart but complement it by taking up much of the function.

The first Left Ventricular Assist Device (LVAD) system was created by Domingo Liotta at Baylor College of Medicine in Houston in 1962.^[29]

Another VAD, the Kantrowitz CardioVad, designed by Adrian Kantrowitz, MD, boosts the native heart by taking up over 50% of its function.^[30] Additionally, the VAD can help patients on the wait list for a heart transplant. In a young person, this device could delay the need for a transplant by 10–15 years, or even allow the heart to recover, in which case the VAD can be removed.^[30]

The first heart assist device was approved by the FDA in 1994, and two more received approval in 1998.^[31] While the original assist devices emulated the pulsating heart, newer versions, such as the Heartmate II,^[32] developed by the Texas Heart Institute of Houston, Texas, provide continuous flow. These pumps (which may be centrifugal or axial flow) are smaller and potentially more durable and last longer than the current generation of total heart replacement pumps. Another major advantage of a VAD is that the patient can keep the natural heart, which can receive signals from the brain to increase and decrease the heart rate as needed. With the completely mechanical systems, the heart rate is fixed.

Several continuous-flow ventricular assist devices have been approved for use in the European Union, and, as of August 2007, were undergoing clinical trials for FDA approval.

References

1. ^ ^{a b} http://www.fda.gov/cdrh/mda/docs/p030011.html
2. ^ ^{a b} http://www.syncardia.com
3. ^ http://content.nejm.org/cgi/content/short/351/9/859
4. ^ http://www.fda.gov/cdrh/pdf4/H040006a.pdf
5. ^ http://www.fda.gov/cdrh/ode/H040006sum.html
6. ^ "Abiomed claims its 1st implanted artificial heart". http://www.businessweek.com/ap/financialnews/D9917PE80.htm. 
7. ^ http://phx.corporate-ir.net/phoenix.zhtml?c=95629&p=irol-newsArticle&ID=1326498&highlight=
8. ^ American Heart Association. The Mechanical Heart celebrates 50 lifesaving years. 22 10 2002. 9 Feb 2008 <http://www.americanheart.org/presenter.jhtml;jsessionid=EFNP3NSFUBXLICQFCXQCDSQ?identifier=3005888>
9. ^ Wayne State University | School of Medicine
10. ^ Stephenson, Larry W, et al. "The Michigan Heart: The World's First Successful Open Heart Operation?" Journal of Cardiac Surgery 17.3 (2002): 238-246.
11. ^ Lavietes, Stuart. "William Glenn, 88, Surgeon Who Invented Heart Procedure", The New York Times, March 17, 2003. Accessed May 21, 2009.
12. ^ Artificial Heart in the chest: Preliminary report. Trans.Amer. Soc. Inter. Organs, 1961,7:318
13. ^ Ablation experimentale et replacement du coeur par un coer artificial intra-thoracique. Lyon Cirurgical,1961, 57:704
14. ^ Sandeep Jauhar, M.D., Ph.D. "The Artificial Heart." New England Journal of Medicine (2004): 542-544.
15. ^ Orthotopic cardiac prosthesis for two-staged cardiac replacement. Am J Cardio 1969;24:723-30.
16. ^ Spare Parts: Organ Replacement in American Society. Renee C. Fox and Judith P. Swazey. New York: Oxford University Press; 1992, pp. 102–104
17. ^ Kwan-Gett CS, Van Kampen KR, Kawai J, Eastwood N, Kolff WJ. “Results of total artificial heart implantation in calves.” Journal of Thoracic and Cardiovascular Surgery. 1971 Dec;62(6):880-9.
18. ^ Winchell's Heart - TIME
19. ^ Kolff
20. ^ ^{a b} "Patient gets first totally implanted artificial heart". CNN.com. 2001-07-03. http://archives.cnn.com/2001/HEALTH/conditions/07/03/artificial.heart/. Retrieved 2008-07-13. 
21. ^ "AbioCor FAQs". abiomed.com. http://www.abiomed.com/products/faqs.cfm. Retrieved 2008-07-13. 
22. ^ ^{a b} "FDA Approves First Totally Implanted Permanent Artificial Heart for Humanitarian Uses". FDA.gov. 2006-09-05. http://www.fda.gov/bbs/topics/NEWS/2006/NEW01443.html. Retrieved 2008-07-13. 
23. ^ ^{a b} "Will We Merge With Machines?". popsci.com. 2005-08-01. http://www.popsci.com/scitech/article/2005-08/will-we-merge-machines. Retrieved 2008-07-13. 
24. ^ "14th Artificial Heart Patient Dies: A Newsmaker Interview With Robert Kung, PhD". medscape.com. 2004-11-11. http://www.medscape.com/viewarticle/493622. Retrieved 2008-07-13. 
25. ^ Capital Health: One year later: Berlin Heart bridges patient back to health
26. ^ news.yahoo.com, Total artificial heart to be ready by 2011: research team
27. ^ timesonline.co.uk, Scientists develop artificial heart that beats like the real thing
28. ^ afp.google.com, Total artificial heart to be ready by 2011: research team
29. ^ Prolonged Assisted circulation after cardiac or aortic surgery. Prolonged partial left ventricular bypass by means of intracorporeal circulation. This paper was finalist in: The Young Investigators Award Contest of the American College of Cardiology. Denver, May 1962 Am. J. Cardiol. 1963,12:399-404
30. ^ ^{a b} Mitka, Mike. "Midwest Trials of Heart-Assist Device." Journal of the American Medical Association 286.21 (2001): 2661.
31. ^ FDA APPROVES TWO PORTABLE HEART-ASSIST DEVICES at FDA.gov
32. ^ An Artificial Heart That Doesn't Beat at TechnologyReview.com

George B. Griffenhagen and Calvin H. Hughes. The History of the Mechanical Heart. Smithsonian Report for 1955, (Pub. 4241): 339-356, 1956.

External links

• Artificial hearts and heart assist devices currently in use
• The story of Bill Sewell, who built the first artificial heart pump from pieces of a child's Erector set, laboratory odds and ends, and dime store goods

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