The Heart

Your heart is a muscular organ roughly the size of your fist, situated behind and slightly left of your breastbone.
It is responsible for pumping blood through a network of arteries and veins - this is your cardiovascular system.

Heart transplant facts

You can have more than one organ transplanted at the same time. For instance, some people have a heart and lung transplant
A human heart was first transplanted in 1967
In 1964, in the USA, surgeons performed the first animal-to-human heart transplant on record, using a chimpanzee's heart
Even when resting, the muscles of the heart work hard - about twice as hard as the leg muscles of a person sprinting
Your heart can pump blood to every cell in your body in less than a minute

Common reasons for transplantation

The reasons for which patients may need a heart transplant tend to fall into two major categories: cardiomyopathy and coronary heart disease.

Cardiomyopathy is a disease of the heart muscle. The heart becomes weakened or stiffened and when medications and treatments fail, a heart transplant may be the only option.

Coronary heart disease is caused by blockages or narrowing of the blood vessels leading to the heart. Several treatment options are available, but when a patient's life is still at risk, a heart transplant may be seen as the only option for extending life.

How the heart works

Your heart is a pump that moves blood around your body. This delivery system supplies oxygen and nutrients to all parts of your body, and carries away unwanted carbon dioxide and waste products.

Your heart has two separate sides, but they work together. The right side of the heart receives dark, de-oxygenated blood which has circulated around your body supplying it with what it needs. This gets pumped by the heart to your lungs, where it receives a fresh supply of oxygen and becomes bright red and oxygen-rich again.

The cardiovascular system

This circular movement of blood around the body, pumped by your heart, is called the cardiovascular system (or circulation).

Blood leaves through the left ventricle to the aorta, your body's largest artery. It is almost the diameter of a typical garden hose. The aorta leads to smaller arteries, arterioles, and finally capillaries, which are so small you would need ten of them to match the thickness of a human hair.

The heart's other parts

Like every other living tissue, your heart needs a steady supply of fresh blood. This blood supply comes from coronary arteries that run along its surface carrying oxygen-rich blood to the heart muscle.

The heart's pumping action is a result of the muscle contracting and relaxing repeatedly. The complex signals that produce this are created by a web of nerve tissue that runs through the heart.

Surrounding the heart is a sac called the pericardium.

When it goes wrong

Heart problems can develop for many reasons, or may exist from birth if the heart never developed properly. For example:

  • A heart may develop problems if the arteries supplying blood become too narrow or get completely blocked.
  • Disease or illness can cause the heart to become enlarged, thickened or stiffened, leaving it unable to work effectively.
  • The pumping rythmn of the heart can become irregular

Heart transplants

A heart transplant is a procedure in which a surgeon removes a diseased heart and replaces it with a donor heart. During a heart transplant, a mechanical pump circulates blood through the body while the surgeon removes the diseased heart and replaces it with a healthy heart.

The surgeon connects the donor heart to the major blood vessels and hooks the heart up to wires that temporarily control the heartbeat. The procedure takes several hours.

History and progress of transplantation

In 1967, the first successful human heart transplant took place in Cape Town. A South African surgeon named Dr. Christiaan Barnard transplanted a new heart to his patient, Louis Washkansky, a 55-year-old man dying of heart damage. Mr Washansky survived for 18 days.

This first clinical heart transplantation experience gained international interest, and many surgeons were quick to repeat the procedure. However, success rates were not high and the 100 transplants carried out in 1968 quickly dropped to only 18 by 1970. It appeared that the major problem was the body's natural tendency to reject the new tissues.

Improving survival rates

Over the next 20 years, important advances in tissue typing (compatibility testing) and immunosuppressant drugs allowed more transplant operations to take place and increased patients' survival rates.

The most notable development in this area was Jean Borel's discovery of cyclosporine, an immunosuppressant drug derived from soil fungus, in the mid 1970s. The first immunosuppressant drugs used in organ transplantation were the corticosteroids. Thanks to the persistence of pioneers like Borel, transplant patients have dramatically expanded life expectancies.

Mini Glossary

  • Immunosupressant
    Drugs inhibit the activity of the body's immune system.
  • Tissue typing
    Checks the compatibility of the tissue of a donor with that of the recipient before transplantation.
  • Cortiscosteroids
    Are man-made drugs that resemble a naturally-produced hormone, cortisol. They are used as anti-inflammatory medicines.

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