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Over the last few centuries, the face of healthcare in the world has radically changed. With advances in the scientific method and empirical observations, medicine has been able to advance to an unprecedented level. As the world has become increasingly industrialized, population plaguing epidemics have been nearly eradicated. Diseases such as cholera, tuberculosis, smallpox, and typhoid had plagued large populations for hundreds of years. As medicine was improved and the prevalence of these diseases was decreased, the quality of life of the average human and the world life expectancy rates have both increased. With the increase in life expectancy, there are new burdens which face the medical world today. In the United States, nearly 1 in 3 adults has a heart related disease, and 1 in 2.9 deaths are due to heart related illness1. As such, there is an increased demand to treat diseases of this type. One way in which physicians and engineers have decided to combat this illness is the invention of the artificial heart. The artificial heart is a device which has been developed to help patients in their fight against disease, and its history has molded together engineering and medicine in an attempt to outwit Mother Nature in one of her most complicated creations. The following will analyze the introduction of this technology into the healthcare scene of the United States from its inception to its use in healthcare today.
Heart failure affects nearly 600,000 patients in the United States each year, and cardiac transplantation (a heart transplant) remains the "most effective long-term treatment strategy for advanced heart failure"2. However, as can readily be seen through the economic lens, the demand for donor hearts greatly overweighs the supply. For the last three decades, the supply of donor hearts for transplantation has been limited to 2,100 per year, while the demand is much, much more at around 100,000 per year2,3. This discrepancy between demand and supply has caused engineers and physicians to work together to develop a new product which can combat the rising prevalence of the disease.
The treatment of heart related illnesses in the United States has increased in its complexity since the 1960's. It was at this time that the leading international cardiologists were honing their craft on the ability to transmit a heart from a donor to the recipient. However, as the surgeons were increasing in their abilities to perform the procedure, there was an extreme shortage of in the number of hearts available for donation. This deficit produced the need for the total artificial heart. The total artificial heart is a biomedical device which is used to provide "complete circulatory support in patients who are awaiting cardiac transplantation"2.
The device has a history that is primarily confined to the last two hundred years. Until the advent of the industrial revolution, there was simply not the vast array of materials or medical standards which could simulate such a daunting task. Despite these drawbacks, some of the earliest history of the device stems from 1810 with the observations postulated by CJJ LeGallois in his Experiences sur les Principles de Vie (Experiences of the Principles of Life)8. LeGallois proposed using extracorporeal perfusion to support a failing heart4. This postulation is the earliest known advance of the idea of using an artificial heart, and it succeeded in stimulating thought about the concept. A way of achieving this frequently evaded the abilities of researchers. However, beginning in the 1900s capable minds came together regarding the task and brainstormed the concept of using compression to move blood through the body via a pumping chamber4. In the 1920s famous inventor, innovator, and aircraft pilot Charles Lindbergh became enthralled in the idea of creating a device which could be used during open-heart surgery which could mechanically stimulate the process of blood perfusion in the body4. The process of innovation continued throughout the 1930s-1960s. In Moscow in 1951, Vladimir Demikhov created an artificial heart which successfully kept a dog alive for 5 Â½ hours9. This device motivated thought in the medical world, where they hoped the device could be installed into a human who had heart failure to keep him alive while a suitable heart donor could be found.
In the 1930s, leading cardiovascular surgeons were increasing the number of cardiopulmonary bypass and open heart operations. Surgeons such as Dr. Michael DeBakey, at Baylor College of Medicine in Houston, were world renowned in such operations as bypass and open heart operations, and realized the value of creating an artificial heart which was able to provide life prolonged life support for patients who could not be stimulated by bypass and were dying of severe heart failure8. In 1957, the research team of Drs. Akutsu and Kolff implanted the first Total Artificial Heart in vivo, creating a pneumatic pump which maintained a dog's circulation for 1.5 hours4. However, they were still unsuccessful in human applications. It did not take long for national programs to become involved in the initiative as well. In 1963, the American Society for Artificial Internal Organs testified before the United States Congress stressing the importance of developing an artificial heart5. Soon thereafter, the National Heart Institute, backed by Congress, established the first artificial heart program, seeding a government funding of over $500,000 with the goal of surgically inserting a man-made organ into a living human by the end of the 1960s3.
At the same time as all the excitement raised around ambitions for an artificial heart, there were advances in the cardiovascular field which made such future efforts palpable. In 1967, Dr. Christiann Barnard performed the first total cardiac transplantation in South Africa4. This increased the intellectual perspective across the world and raised hopes that an artificial heart could be developed which would be possible to transplant into a human to achieve the same result. As the capabilities of heart transplants using real tissue from a donor were advanced, so too were the drawbacks and complications of the procedure, consisting of infections and rejections post-procedure, which increased the desire for an artificial heart even more4. Much of the research on the artificial heart which was done in the 1970s included the research of processes and materials which could support such a device in the human body. The development of the various biomaterials alone justified the expenses for the entire project. Some of the various products which were investigated were polyurethane and plastic pumps5. These products had developed into a trusted state over time, due to extensive background testing in animal clinical testing.
The goals set by the National Institutes of Health were culminated with the actions of Dr. Denton Cooley. In 1969, Cooley performed a significant accomplishment for cardiovascular science. He was a surgeon at the Texas Heart Institute in Houston, and successfully installed a total artificial heart as a bridge between the transplantation of a donor heart organ3. Even though the patient eventually died after the donor heart was transplanted, it was deemed a great success for the science since Cooley was able to keep the patient alive with the implanted total artificial heart for a period of three days. It is important to note that this trial was only a short term designation, and it would be more than a decade before an artificial heart was used for long term therapy.
The land mark day of artificial organ transplantation came on December 2nd, 1982. It was on this day that a retired dentist named Dr. Barney Clark was to receive the first permanent total artificial heart in the surgery center at the University of Utah Medical Center in Salt Lake City3. Due to his prior medical conditions, specifically relating to his severe emphysema, Clark was not deemed qualified to receive a living tissue heart transplant from a donor6. It was because of this fact, and his deteriorating level of heart disease, that Barney Clark was introduced to the Jarvik-7 artificial heart at the University of Utah. The device was constructed of aluminum and polyurethane, had two separate ventricles, had connections to the major blood vessels made of Dacron felt, and was powered by an external air compressor weighing nearly 400 pounds3,6. The device had been through a large system of animal testing, and had a calf at the University had recently been supported for months by the device. After seeing the device, Dr. Clark indicated to the physicians he would like to use medicine alternatives before transplantation of the artificial heart.
The situation radically changed when Dr. Clark's heart, lungs, and kidneys all came under organ failure, and the decision was made to install the Jarvik-76. When the patient became conscious 3 hours after the operation, he found himself with a functional heart and working kidneys. The operation was performed by Dr. William DeVries. The patient was continuously monitored, and there were complications with the procedure on the 13th day resulting in the need for a second operation to repair the valves which had broken down in the device6. There were additional complications with seizures and intestinal problems, as the flow of the heart was set to 12 litres per minute and there was frequent overmedication of antibiotics6. Although Dr. Clark eventually died of kidney failure 112 days after the operation and was never discharged from the hospital, the operation was deemed a success as after the surgery his condition slowly improved6. After this operation, the device was moved from the University of Utah Medical Center to the Humana Hospital in Louisville, Kentucky where it enjoyed successes in three additional Jarvik-7 implantations as permanent replacements for a tissue based heart4. The longest living patient of these three died 620 days post-implantation of a stroke. However, the complications attributed to the device and the procedure, combined with the exorbitantly large cost of the device, caused the Food and Drug Administration to withdraw permission for further construction of Jarvik-7 devices, effectively ending them as products for heart transplantation3,4.
When the complications arising from the Jarvik-7 were seen by leaders in the cardiovascular industry, the decision was made to develop a better artificial heart which could be completely implantable. This device would be self-contained, powered internally, and would have no wired connections outside of the skin. This program was initiated by the NHLBI in 1988, funding the Texas Heart Institute and Pennsylvania State University-Sarns to produce ABIOMED (AbioCor) devices4. This device is made of polymer and titanium, requires no external venting, and produces 2 horsepower4. This device began its clinical testing and implantation phases in July 2001; however, 6 of the first 7 patients died either preoperatively or from strokes3. The device has been improved in its design to allow for fewer areas of blood stagnation to prevent strokes from occurring due to coagulating blood during pumping. The future of the device looks bright. Although it finds itself in the middle of the rigorous testing procedures imposed by the Food and Drug Administration, the designers of the product are optimistic. At this time it joins the SynCardia artificial heart as the only total artificial hearts which are powered transcutaneously, it look to avoid most of the complications which arise from infections such as those in percutaneously powered devices5,7. The product is currently in phase 1 clinical testing at six different medical centers across the United States, with patients surviving on average 5-6 months3. Improvements need to be made on the device before it can be manufactured for the mass market. At the current time the device would only fit 50% of males and only 20% of females, while it would not be able to fit any children due to its large size4. However, there is indeed a future for the product, as recently, Tom Chirsterson, one of the beneficiaries of the AbioCor device, has been the first patient discharged from the hospital and lives at home4.
The history of the development of the total artificial heart has been filled with simultaneous optimism and setbacks. Developers such as Robert Jarvik and Dr. Denton Cooley have been able to devise devices which seemingly imitate one of the most complicated organs in the human body. While there have certainly been complications, such as the FDA shutting down the Jarvik-7 device in 1990 due to excessive failure rates, the positive outcomes being reported in the AbioCor and SynCardia devices create hope that there is indeed a future for total artificial heart technology. Since the idea was envisioned by LeGallois in 1810 and enacted in the 20th century, there have been over 1300 patients which have benefited from the technology5. There are approximately 100,000 patients which could benefit from heart transplant surgery, but there are only 2000 donor hearts becoming available each year3,4,5. Indeed, there remains a heavy hope for these devices to succeed to fill this gap between supply and demand. If there is anything that the study of the history of engineering and technology has taught us, is that it is only a matter of time before an individual responds to the demands of a society. It is the hope of many that this call will be answered by the AbioCor and SynCardia devices in the years to come.