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after heart

Artificial heart

An artificial heart is a prosthetic device that is implanted into the body to replace the biological heart. It is distinct from a cardiopulmonary bypass machine (CPB), which is an external device used to provide the functions of both the heart and the lungs. The CPB oxygenates the blood, and therefore does not need to be connected to both blood circuits. Also, a CPB is suitable only for a few hours use, while artificial hearts have been used for periods longer than a year ().

Types

Total Artificial Heart (TAH) implantation involves the removal of the native heart. It is a surgical procedure similar to heart transplantation with a human donor heart.

Cardiac (heart) assist devices differ from the TAH, in that the patient’s heart is not removed during implantation. Assist devices may include either a Left Ventricular Assist Device (LVAD) or a Right Ventricular Assist Device (RVAD) or both. As opposed to TAH implantation, the assist device serves to provide only a part of the total cardiac output of the patient’s heart.

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 donor hearts (as it is for all 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 artificial heart, performed the operation and developed the heart-lung substitute himself. This was the first artificial heart.

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.

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.

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

Early designs of total artificial hearts

The first artificial heart implanted in a living being was placed in a dog at the Cleveland Clinic in 1957; it survived about 90 minutes. 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.

In 1958 Domingo Liotta started 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 meeting held in Atlantic City in March 1961. On that meeting Dr Liotta described the implantation of three types of orthotopic (inside the pericardial sac) TAH 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.

Early clinical application of assisted circulation and total artificial heart

The Left Ventricular Assist Device (LVAD) system was created by Domingo Liotta at Baylor University College of Medicine in Houston in 1962.

First clinical application of an intrathoracic pump

In 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 4 days under mechanical support but didn't recover from the complications of the cardiac arrest; finally the pump was discontinued and the patient died.

First clinical application of a paracorporeal pump

In 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 hospital after 10 days of mechanical support, thus constituting the first successful use of an LVAD for postcardiotomy shock.

First clinical implantation of a total artificial heart

In the morning of April 4 1969 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 drugs complication. If they had left the artificial heart in place the patient may have lived longer.

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, DC.

First clinical applications of a permanent 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. 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. Independently, ventriloquist Paul Winchell designed and patented a similarly shaped ventricle, and donated the patent to the Utah program. Throughout the 1970’s and early 1980’s 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. On December 2, 1982, Dr. William DeVries implanted the artificial heart into retired dentist Dr. Barney Bailey Clark (b. 21 January 1921), who survived 112 days with the device, dying on 23 March 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. Since 1982 more than 350 people have received the Jarvik heart. http://www.jarvikheart.com/basic.asp?id=69

First clinical applications of a permanent fully implantable total artificial heart

The AbioCor is the first fully implantable total artificial heart which unlike previous total artificial hearts (such as the Jarvik 7) does not require wires to external devices. This allows for free movement and a reduced risk of infection. The first AbioCor to be surgically implanted in a patient was on July 3, 2001. The AbioCor is made of titanium and plastic with a weight of 2 pounds and its internal battery can be recharged with a transduction device that sends power through the skin. The internal battery lasts for half an hour and a wearable external battery pack lasts for 4 hours. 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. It is intended for critically ill patients who can not receive a heart transplant. Some limitations of the current AbioCor is that because of its size it is implantable in only 50% of the male population and has a life span of 1 to 2 years. The AbioCor II which is in development will be smaller and should be implantable in most men and 50% of women with a life span of up to 5 years. The AbioCor II had animal trials in 2005 and the company hopes to get FDA approval for human use in 2008.

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, Canada. 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.

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.

Heart assist devices

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. One such VAD, the Kantrowitz CardioVad, designed by Adrian Kantrowitz, MD boosts the native heart by taking up over 50% of its function. 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.

The first heart assist device was FDA approved in 1994, and two more received approval in 1998. While the original assist devices emulated the pulsating heart newer versions, such as the Heartmate II, 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 long-lasting 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 at August 2007 were undergoing clinical trials for FDA approval.

In fiction

The earliest example of a fictional artificial heart is the French pulp hero the Nyctalope.

In the fictional Star Trek universe, Captain Jean-Luc Picard had an artificial heart implanted in 2327, which was later replaced. A power surge from it almost killed him in 2369. Joseph Sisko, father of Benjamin Sisko, had several artificial organs, including a new aorta he received in 2372.

The British science fiction series Space: 1999 had a character, Victor Bergman (portrayed by Barry Morse), with an artificial heart. He was able to modify its rate of operation with a wrist-worn device.

The novels of Philip K. Dick feature the use of 'artiforgs' or artificial organs.

In the 1981 movie Threshold, it is stated from IMDB, that "The celebrated heart surgeon Dr. Vrain supports the research of the offbeat scientist Aldo Gehring, who is inventing an artificial heart. Dr. Vrain performs the first artificial human heart transplant against the advice of the Ethics Committee." This movie, which stars Donald Sutherland and Mare Winningham, is a study in artificial heart transplant, though it is fictional.

The German heavy metal band Accept wrote about artificial hearts in their album Metal Heart (1985).

German synthpop musician Peter Schilling sings about a plastic heart in the song "Lifetime Guarantee" on the 1983 album Error In The System.

In the 1987 movie Robocop, there is a commercial for an artificial heart clinic called "The Family Heart Center" where surgeons operate on persons and implant artificial hearts from "the complete line of hearts by Jensen and Yamaha," encouraging its customers "You pick the heart!" These hearts come with extended warranties, financing, and qualify for "health tax credit."

The computer game Syndicate (by Bullfrog) features humans agents the player can modify bionically, including replacing the heart with more and more advanced technology.

In the anime series Sentou Yousei Yukikaze, the engineer Tom "Tomahawk" John possesses a nuclear-powered artificial heart. While this allowed him to be nearly fully mobile, the fact that it used nuclear power prevents him from visiting some foreign countries.

In the 1986 sequel King Kong Lives, King Kong, after being shot down from the World Trade Center, is kept alive in a coma for about 10 years at the Atlantic Institute, under the care of surgeon Dr. Amy Franklin (Linda Hamilton). In order to save Kong's life, Dr. Franklin must perform a heart transplant and give Kong a computer-monitored artificial heart.

References

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

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