The body’s hardest working muscle, the heart beats about 70 times each minute as it pumps blood throughout the body.
Cardiovascular disease kills more Americans than any other disease. Smoking cigarettes, obesity, lack of exercise, diabetes, hypertension and a family history of heart disease are all risk factors for heart disease.
A wide range of advanced heart diseases make heart transplants necessary; most common are coronary artery disease and cardiomyopathy or weakening of the heart muscle. Other disorders, such as heart valve diseases, congenital defects and viral infections can lead to transplantation.
Almost 2,200 heart transplants occur in the U.S. each year. Most heart recipients return to full and active lives, and almost 75 percent of transplanted hearts are functioning after five years.
There are nearly 3,500 people on the U.S. heart waiting list. About one-third of patients get their transplant in a year; close to half wait more than two years. Every year, about 600 people die while waiting for a heart. Because the number of donated hearts is limited, many people who might benefit from heart transplantation are never placed on the waiting list.
A partial mechanical heart called an LVAD can be surgically implanted to help maintain the heart’s pumping ability until a donated heart becomes available.
The trachea or windpipe carries air to the lungs, where alveoli-tiny air sacs that are like folded balloons-extract oxygen and exchange it for carbon dioxide.
Elastic and spongy, lungs are divided into sections called lobes: three on the right and two on the left. A person in good health can lead a normal life with only about thirty percent of normal lung function.
More than 35 million Americans are now living with chronic lung disease, and every year, close to 342,000 die of lung disease making it America’s number three killer.
The primary condition leading to lung transplantation is chronic obstructive pulmonary disease, a term describing airflow obstruction associated primarily with emphysema and chronic bronchitis. Other conditions that can generate a need for new lungs are idiopathic pulmonary fibrosis, cystic fibrosis, and primary pulmonary hypertension.
Although some conditions that lead to transplantation are hereditary, most are caused-and worsened-by smoking and environmental pollution.
To get on the lung transplant list, a person with end-stage lung disease must have progressive disability and lung disease that is unresponsive to other treatments. Many patients awaiting lung transplant are severely disabled and require oxygen 24 hours a day.
Nature gives us two kidneys even though we can lead normal lives with only one. In adults, each kidney is about five inches long and weighs about a quarter of a pound.
Blood flows from the heart through the aorta and into the kidneys, which filter wastes and excess water from the blood and balance the body’s fluids. The kidney also release hormones that regulate blood pressure, control production of red blood cells, and promote growth of healthy bones. Urine is one by-product of the kidneys elaborate blood filtering system.
Common causes of kidney failure include diabetes, high blood pressure. as well as diseases. many of them inherited, which damage the nephrons and other fragile structures deep within the kidney. People whose kidneys fail will die unless they receive transplants or dialysis treatments, which involve a machine that filters wastes from the blood.
Kidneys that are transplanted are donated either by live donors or by people who have died. Most people receive one transplanted kidney, which surgeons place in the front of their lower abdomen, cradled by the hipbone; failed kidneys are usually left in place.
People with transplanted kidneys almost always stay healthier and live longer than do people on long-term dialysis.
The body’s largest organ. the liver weighs about three pounds. It is well protected, behind the lower right ribs and is located on top of the intestines, stomach and right kidney. The liver has two lobes — one small left lobe and a large right lobe — both of which perform the same functions. At any given moment, the liver holds about one pint of blood, 13 percent of the body’s supply.
The liver is a complex organ that has more than 500 known functions. It breaks down harmful substances in the blood including drugs, poisons and alcohol. The liver produces bile that aids in digestion and also stores vitamins, sugars and fats.
The principal causes of liver failure leading to transplantation are viral infections like Hepatitis C, genetic disorders and alcoholism. Many liver diseases cause cirrhosis, scarring that occurs with inflammation. Scar tissue blocks the flow of blood, preventing the liver from functioning properly. Symptoms of liver disease may include jaundice, nausea and vomiting, dark-colored urine, fatigue and sudden weight changes.
Living donation is possible because the liver is the only organ that can regenerate itself; an adult can give a lobe to a child or another adult. The donor’s liver fully regrows within four months and is indistinguishable from the pre-donation liver. A liver from a deceased donor can also be split and transplanted into two people.
The intestine extends from the stomach to the anus. The upper, small intestine (also called the small bowel) is narrow and about 20 feet long. It digests food and absorbs nutrients from digested food. The lower, large intestine (called the colon and the large bowel) is wider and about five feet long; it reabsorbs water from the digested foods and sends it back into the bloodstream.
Diseases, congenital defects or trauma that affect the way the small intestine absorbs nutrients or moves food through the intestinal tract may lead to transplantation. Symptoms of intestinal failure include persistent diarrhea, dehydration, muscle wasting, poor growth, frequent infections, weight loss, and fatigue.
The most common reason leading to transplantation is short bowel syndrome resulting from tumors, Chron’s and other inflammatory bowel diseases, congenital defects, trauma and other causes.
Small intestine transplantation can be performed in one of three ways: alone, in combination with the liver, or in combination with the liver, pancreas, stomach, duodenum or colon.
The large intestine is not necessary to sustain life, so it has been transplanted only in rare circumstances, and always in conjunction with the small intestine. This practice has been abandoned however, because the risk of infection is too high.
The pancreas — which is five inches long-produces insulin, a hormone that helps the body use glucose (sugar) for energy. The pancreas also generates enzymes that help break down fat, protein and carbohydrates during digestion. About five percent of the pancreas consists of cell clusters — islet cells — that produce insulin.
When insufficient insulin is available, a build-up of sugar in the blood — called diabetes — can lead to kidney failure, heart disease, strokes, circulatory problems and even death. It can also damage the small blood vessels of the eye, which is the leading cause of blindness in the U.S.
Type 1 diabetes – previously called juvenile diabetes – is the most common disease leading to pancreas transplantation, which can free the recipient from dependence on daily insulin injections. Surgeons insert the donor pancreas in the patient’s abdomen, and leave the patient’s diseased pancreas in place. combined kidney-pancreas transplants are often done when diabetes has led to kidney failure.
Experimental transplants of pancreas islet cells are also now performed. In this procedure, the insulin-producing islets cells are isolated from the pancreas and injected into the patient’s portal vein in the liver. In a successful transplant, the transplanted cells take up residence in the recipient’s liver and begin to produce insulin.
Blood is produced in the bone marrow. It carries oxygen and nourishment to the cells, and removes wastes. Like skin, it is technically an organ because it is distinct from the rest of the body and has a specialized function. Blood has four principal components: red blood cells, white blood cells, platelets, and plasma.
Blood types-discovered in the early 1900s-are determined by antigens on the surfaces of red blood cells; the two most important known categories of antigens are blood group antigens (ABO) and the Rh antigen, also called the Rh factor.
About five million people receive donated blood in the U.S. each year-that is about one every two seconds. These blood "transfusions" are used primarily during surgery, in treatment of trauma or burns, and for people with blood disorders.
Donated blood is also used during organ transplants. In certain circumstances, 10 or more units of blood might be required for a liver transplant.
About five percent of all medically eligible donors contribute the blood that makes this possible.
The average adult has 206 named bones, which constitute about 20 percent of their body weight. Bones may seem lifeless, but consist of living protein fibers that constantly rebuild themselves. Tendons attach muscle to bones and ligaments attach bone to bone or bone to cartilage.
Traumatic or athletic injuries, degenerative diseases like arthritis, and cancerous tumors can destroy bone tissue and joints causing pain and disability. Donated bone and connective tissues including tendons, ligaments and cartilage are used every day to help treat hundreds of different types of procedures to reduce pain, restore mobility and save limbs from amputation.
Bone is the most commonly transplanted part of the body. The number of bone grafts also known as allografts, and the ways in which bone is used, increases each year ranging from whole tibia replacement to spinal fusions, joint reconstruction and dental surgery.
Donated bone, ligaments and tendons are processed by bone banks and made available to surgeons as needed. Donated bone helps patients avoid having to use an "autograft" or segment of their own bone, reducing pain and potential for infection. Bone grafts also have advantages over synthetic materials because they will stimulate new bone growth at the site of the transplant.
The cornea is the clear. dome-shaped window covering the front of the eye. There are more nerve endings in the cornea than anywhere else in the body making it one of the most sensitive parts of the body.
Clear vision or sight begins with light entering the eye through the cornea. Most common vision problems are directly related to problems with the
shape of the cornea. If the cornea becomes seriously misshapen, scarred or otherwise damaged. blurred vision or blindness can result.
Sight-restoring cornea transplants are also called corneal grafts and penetrating keratoplasty.
The most common problem leading to a cornea transplant is damage to the cornea from certain types of lens implants to correct cataracts. The next most common reason for a cornea transplant is keratoconus, a disease that causes the cornea to become thin and cone-shaped often affecting people in their 20s and 30s. Over time, the cornea becomes so misshapen that vision cannot be corrected with contacts or glasses. Other causes of cornea damage include injuries, burns and infections.
Donated corneas must be processed and placed in preservation solution within 8-12 hours after the donor’s death; to maximize chances of success, the transplant must occur within two weeks.
Blood is pumped through the heart’s four chambers aided by four heart valves that open and closed and prevent blood from flowing backward. The four valves include: the tricuspid valve between the right atrium and right ventricle; the pulmonary valve between the right ventricle and the pulmonary artery; the mitral valve in between the left atrium and left ventricle; and the aortic valve between the left ventricle and the aorta.
Infections and aging related diseases can damage heart valves; many children are also born with malformed valves.
Heart valve replacement surgery has been a routine part of modern medicine since the 1980s. About 95 percent of all valve replacements are the mitral or aortic valves-both of which are located on the left side of the heart, which pumps out oxygen-rich blood.
Patients have three options for valve replacements: porcine or pig valves, mechanical valves and human valves. Donated human heart valves have advantages over others including greater resistance to infection and no need for blood thinning drugs required with mechanical valves.
Donated valves are recovered from tissue-only donors and from organ donors whose hearts are not suitable for transplantation.
Marrow or "bone marrow" is the soft tissue in the cavities of bones involved in the production of blood cells in the body. Every year, thousands of people need donated marrow to treat a range of diseases and blood disorders.
The crucial element in marrow is blood stem cells, immature cells from which all blood cells develop including red blood cells, white blood cells, and platelets; some also divide to form more stem cells. Those that float in the blood system are called peripheral blood stem cells.
Marrow transplantation replaces the diseased marrow of the donor with marrow from a living donor. Marrow or blood stem cells are "infused" just like blood into the patient’s arm.
Marrow transplantation is used to treat more than fifty major illnesses, including cancer and serious blood disorders like sickle cell anemia.
If the transplant is successful, new marrow makes a home in the recipient’s bones,
and begins to divide into more stem cells, producing normal, healthy blood cells within two to four weeks. This is called an "engraftment." The donor’s marrow usually replaces itself in about three to four weeks.
About 21 square feet of skin, weighing up to fifteen pounds, covers the average adult.
Skin is the body’s first line of defense against microbes, and also regulates heat and fluids in the body. It consists of two principal layers: the outer epidermis and beneath it the dermis, which gives skin its strength and elasticity.
Severe burns or other major injuries to the skin expose someone to infections and fluid loss that can turn fatal. Donated skin can help heal burns.
Donated skin can mean the difference of life or death for burn victims. A skin transplant or graft serves as a temporary covering and barrier while the recipients own skin heals. Skin grafts are temporary because the recipient’s immune system rejects them. Unlike other organ and tissue transplants, this is a desirable part of the healing process.
If donated skin is not available, physicians rely on artificial skin, which the recipient’s immune system rejects in about the same time as it rejects donated skin. Physicians usually prefer to use human skin as a graft, if available, because it produces better results in terms of less scarring and pain, and fewer infections.
Arteries carry oxygenated blood from the heart to the rest of the body, and veins bring the deoxygenated blood back.
Diseases that can harm arteries include atherosclerosis, a narrowing and hardening due to the accumulation of fatty deposits often affecting the coronary arteries in the heart and the arteries in the legs. Atherosclerosis is one of the leading causes of death in the U.S.
Donated veins are used to replace blood vessels that are damaged by disease or trauma. Vein transplants or grafts are frequently used in heart bypass surgery to re-route blood flow from the aorta around a blockage in the coronary artery. Donated veins are used in several thousand vascular transplants in the U.S. each year.
The saphenous vein, a long vein located on the inside of the leg, is the primary vein recovered from donors for transplant. It is processed by tissue banks an cryopreserved or frozen and can be stored for up to two years.