Artificial Hearts: An Alternative to Donors

Every day someone in the world waits for a heart transplant. The only donors come available when someone dies and doctors have legal access to taking the person's heart. Disorders within heart kill more Americans than any other major disease ("Heart Diseases"). Each year only "2,000 human hearts are available for transplants" ("FDA Approves Human Testing of Artificial Heart"). With so few hearts available, alternatives to heart transplants must take place and artificial heart technology is a major alternative. Medical Scientists have developed artificial heart models, which can keep patients alive until a donor heart becomes available ("Building A Better Heart"). Artificial hearts can either replace or assist the patient's real heart with functioning. Artificial heart technology is significant because "heart disease has become the number one killer in the United States," ("Heart History") which is responsible for "more than 700,000 deaths each year" ("Artificial Hearts" URL). Artificial hearts will save lives.

Who Needs an Artificial Heart?

Medical personnel constantly face the issue of ethics. Some patients wait years for a donor transplant and thus force doctors to act as "God" - deciding who gets a real heart transplant. In certain instances heart disease may be so severe the patient may not survive the wait for a donor heart ("Building A Better Heart"). Patients, of course, have diseases of differing degrees and some patients are closer to death than others ("Shortage of Donors"). Patients with severe heart conditions can't take the risk of a heart transplant, so the only chance a patient has at life is with an artificial heart. ("'Permanent' Artificial Heart Implanted"). If "the muscle of the heart is destroyed, as occurs in certain diseases, the only operation that can cure the patient is to replace the heart with a graft [transplant] or possibly an artificial heart" ("The Heart"). Due to the immense complexity of the transplant operation and the difficulty of finding appropriate donors, a transplant is performed only as a last resort in patients whose projected survival with their own heart is only a few weeks or months ("Heart Transplant"). Frequently, heart disease is so advanced the patient has little chance to survive the wait for a donor heart ("Total Artificial Heart (TAH)"). Also, a real heart transplant can't take place because of insufficient supplies (donor hearts). Insufficient supplies creates a longer waiting list and leaves doctors making the decision as to whom gets a real heart transplant.

Several heart related diseases exist today. A well known one is the heart attack. When a heart attack occurs, the patient doesn't always die. The patient suffers tissue death in the heart and the individual feels sudden chest pains. People who survive a heart attack must endure extensive rehabilitation and risk recurrence ("Heart Diseases"). Heart attacks may lead to heart failure. Heart failure occurs when the heart fails, or stops functioning. Heart failure occurs slowly, over time and efficiency in blood pumping diminishes. Web-MD said, "Between 2 and 3 million Americans have heart failure." Web-MD then stated, "Heart failure causes 39,000 deaths a year." The best defense against heart failure is prevention of heart disease. Several of the major coronary risk factors including smoking, high cholesterol, high blood pressure, diabetes and obesity can be controlled or eliminated ("Facts about Heart Failure").

Physiology and Anatomy of the Human Heart

With knowing the human heart's functions and composition, one can better understand the need for an artificial heart and its value. The human heart is roughly the size of a closed fist located within the chest. The heart beats (contracts) rhythmically to pump blood through out the body (Thibodeau, Gary A. and Kevin T. Patton). Heartbeats (contractions) receive electrical stimulation by what is called the sinoatrial node and the atrioventricular node controls these contractions ("Heart"). These nodes are located on the top and bottom of the heart. The heart contains four empty spaces called chambers. Valves reside within the heart chambers to prevent blood back flow from occurring because back flow can cause death. The heart's blood pumping allows blood to gain oxygen and relieve itself of carbon dioxide. Arteries carry blood away from the heart while veins bring blood to the heart (Thibodeau, Gary A. and Kevin T. Patton). Arteries and veins assist in blood circulation, meaning blood gets to and from the body via the heart, while blood gains oxygen and loses carbon dioxide which is a byproduct of the body and thus needs removing from the body. Also, "The heart consists of several layers of a tough muscle wall, the myocardium. A thin layer of tissue, the pericardium, covers the outside, and another layer, the endocardium, lines the inside. The heart cavity is divided down the middle into a right and a left heart, which in turn subdivide into two chambers. The upper chamber is called an atrium (or auricle), and the lower chamber is called a ventricle. The two atria act as receiving chambers for blood entering the heart; the more muscular ventricles pump the blood out of the heart" ("Heart"). Also, "The right atrium receives venous blood from the head, chest and arms via the large vein called the superior vena cava and receives blood from the abdomen, pelvic region, and legs via the inferior vena cava. Blood then passes through the tricuspid valve to the right ventricle, which propels it through the pulmonary artery to the lungs" ("Heart"). This blood then circulates back to the heart for distribution throughout the body. One now realizes the importance of the human heart. The heart is extremely valuable because without it, blood can't circulate through the body and can't rid carbon dioxide while gaining oxygen. No circulation of blood means death. A buildup of carbon dioxide means death. A lack of oxygen means death. The heart is thus a major contributor to maintaining the body by means of blood flow.

Artificial -VS- Human Heart

Action of an artificial heart parallels to a living human heart, however, differences do exist. "Human beings possess complex defense mechanisms against bacteria, viruses, and other foreign materials that enter the body. These mechanisms, which collectively make up the immune system, cannot, unfortunately, differentiate between disease-causing microorganisms and the cells of a lifesaving transplant. Both are perceived as foreign, and both are subject to attack by the immune system. This immune reaction leads to rejection, the greatest problem in successful tissue and organ grafting [transplant]" ("Shortage of Donors"). On the other hand, artificial heart transplants don't face rejection by a patient's immune system (Rothenberg, Robert S. and Wayne M. Barrett). A human heart is living muscle and an artificial or mechanical heart is metal and plastic based ("Building A Better Heart"). Synthetic materials were developed to overcome most of the medical drawbacks and greatly aids in the development of permanent artificial hearts ("Heart-Lung Machine"). Because a mechanical heart doesn't receive power from the patient's body, some external power source is necessary ("Building A Better Heart"). Artificial hearts reside inside a patient; yet require an external power source. "The external components are worn on a waist belt or in an underarm harness and can be hidden under loose fitting clothing." Also, mechanical hearts require constant recharging of batteries (Rothenberg, Robert S. and Wayne M. Barrett). When artificial hearts were first developed in the medical world, artificial hearts were only meant as temporary, but today may become permanent ("Building A Better Heart"). Artificial hearts can be either an assisting device including a pacemaker, which regulates heartbeat within a patient, or an entire replacement for a human heart. Because the artificial heart is a new technology, artificial hearts have many known problems like blood clotting due to poor design. An early design, the "Jarvik-7", was poorly designed because of its sharp corners, which caused blood clotting. Patients may last several days and as progress is made, patients may now live for possibly years ("Building A Better Heart"). "With an artificial heart the patient's lungs are not bypassed." This means the lungs function along with the artificial implant so the artificial implant doesn't need its own supply of oxygen ("Heart-Lung Machine"). Artificial hearts can replace the pumping action performed by the heart for long amounts of time without hurting the patient's blood ("Heart-Lung Machine"). Artificial heart transplants also cost relatively the same as real heart transplants. Receiving an artificial heart can cost less than having a real heart transplant or open-heart surgery ("FDA Approves Human Testing of Artificial Heart").

How to Surgically Implant an Artificial Heart

The patient first receives anesthesia to knock the individual out. The sternum is then cut open. Next, the chest is cracked open then connection of the vessels to a blood pumping-oxygenating machine takes place to keep the patient alive during surgery. The bad heart is then removed from the patient. Now the actual implanting of the artificial heart begins (Kormos, Robert L). Surgical implanting of an artificial heart is done by positioning the driveline exit sites, which are threaded, through the abdominal region. The patient's blood is used to line the insides of the artificial heart to prevent bleeding by allowing the blood to clot. Pre-clotting allows a layer of fibrin to form, which increases the artificial heart's compatibility residing in the patient. The artificial heart is then connected to the ventricles and filled with blood ("Total Artificial Heart (TAH)"). Testing of the power supply to the artificial heart is then performed. Surgeons then decide if the artificial heart needs readjustments and does so as necessary. Adjustments include repositioning the artificial heart, rechecking power supply and sometimes re-wiring blood vessels if a mistake occurred. Finally, with the artificial heart in place with appropriate adjustments, the patient is then sewn up. Assuming the artificial heart functions properly this may extend the patients life beyond what he expected.

How long an Artificial Heart can Extend a Human's Life Span

First of all, no definite time is known. Many people have continuous heart problems, or severe problems affecting their life span. Some patients die within hours of surgery, but the lucky ones have lived only several years. Not only with the patient's medical status, the artificial heart also plays a role in extending a person's life. "Experimental artificial hearts have been implanted, but these require a cumbersome external power supply and long - term survival rates are not known" ("The Heart").

A source I found reads, "The first permanent artificial heart, designed by Dr. Robert Jarvik, was implanted in 1982, in a patient who lived for three months thereafter." It then stated a patient lived almost two years (620 days) with an artificial heart implant ("Artificial Hearts" Encarta). Artificial hearts have clearly been improved since its first creation and patients' longevity have increased, but still remains not truly a 'permanent' transplant, meaning it will last a lifetime.

The Future in Artificial Heart Technology and Development

After reading about longevity with an artificial heart, it leaves you wondering, "Well, what about the future?" Simple, a future exists in artificial heart transplants. Further developments of artificial hearts are underway. Due to this highly useful technology, great profits will be made off of artificial hearts ("Utilization of the Artificial Heart"). Early artificial hearts were ineffective and today's artificial hearts are more effective (Rothenberg, Robert S. and Wayne M. Barrett). Many models have had major complications including blood clotting, but the project of artificial heart technology has never been cancelled, and because of this, artificial heart technology has come a long way. "Development for an artificial heart has continued. One possibility is an electrical heart powered by a small wearable battery that does not require any break in the skin" ("Building A Better Heart"). Also, "Current breakthroughs in valve replacement and mechanical assist devices are buying patients additional time" ("Artificial Hearts" URL). Patients could originally only live several hours, but now may live several years. Once considered temporary, artificial hearts may serve as permanent replacements for a real heart. Artificial hearts have been created as small as a human fist and weighing less than two pounds (Rothenberg, Robert S. and Wayne M. Barrett). "A special task force at the German Heart Institute Berlin has been devoting its efforts for several years to the development of an innovative artificial heart based on magnetic fluids. This type of ambitious endeavor not only requires medical and technical know-how, but also considerable development capacities, professional project leadership, and a sound financial position" ("Utilization of the Artificial Heart"). One of the latest projects underway is the DeBakey device. "The DeBakey device, about half the size of a grapefruit, can take over as much as 75 percent of the work done by the left ventricle, while the heart continues to receive blood from the lungs. The device is removed after the patient's heart is able to function effectively without the pump" ("DeBakey, Michael Ellis"). The best thing about what the future holds is not the profits to make, or job opportunities, but artificial hearts may someday last a person a lifetime. Perhaps someday, the artificial heart will become a realistic, permanent option for survival" ("Building A Better Heart").

Conclusion

With obtaining new insights about artificial hearts you now realize the value of artificial hearts. Artificial hearts were designed to save lives. They have saved lives in a sense, because recipients who never receive the transplant would undoubtedly die. Even though artificial heart transplants have only extended a person's life so long, artificial hearts have still saved their life, just not for very long. Recent developments will definitely allow a person to live the entire human life span, as any other human, with the artificial heart transplant. The ultimate question then becomes "How long will the heart give me?" Some people prefer quality of life and others prefer longevity. Some people accept the fact they have only a few days to live, but they go out and live those last days to the fullest extent. The people who prefer living longer, will have a life changing experience because they know the artificial heart has saved them, and these people may or may not change their life styles. Some people with the artificial heart implanted will take the heart for granted and live life as they once normally did previous to the surgery.

Works Cited

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