Cardiothoracic Services (Heart and Lung)

Cardiothoracic Services (Heart and Lung)

Transforming Lives through organ and tissue donation

Leslie Hamilton is a children's heart surgeon working here at the Freeman Hospital. He specialises in looking after patients born congenital heart disease - children who were born with heart defects.

I only do the plumbing - there's a lot more to it than that

About 8 babies in every 1000 are born with a heart defect. These congenital defects can vary from something quite simple which needs no treatment, to complicated conditions where the heart development has been abnormal. In extreme cases some parts of the heart may be missing. Arteries may be connected the wrong way round. Some babies need surgery soon after birth. The smallest I ever operated on weighed 500 grams; the size of a small bag of sugar. Some conditions do not become known until adulthood.

These days, even when we are not able to correct the heart defect completely, we can usually do something to make the child better. This was not always possible. The first successful operation for a patient born with a heart defect was in 1944. This was a shunt operation used to send extra blood to the lungs in a 'blue child'. (These children look blue because their blood has less oxygen than normal usually because not enough blood is going to their lungs). Today this is a straightforward procedure but in the 1940s it was a major operation which opened the door for future developments.

Pioneering breakthroughs over the years

When surgeons work inside the heart, the patient's blood circulation needs to be supported so the heart can be stopped and opened for the operation. An American surgeon, Walt Lillehei, had the idea of using a parent as the 'heart/lung machine'. The parent lay on one operating table and their blood circulation was connected to the child's by plastic tubes. The parent's heart pumped both circulations. In the 1950s a number of operations were carried out this way. In 1953 there was a major breakthrough when the first mechanical heart/lung machine was used successfully. However this was high risk surgery - of the first 5 patients, only 1 survived. Over many years this machine has been developed into the sophisticated piece of equipment we use today.

The results for congenital heart surgery in babies and children have improved enormously. This is due in part to better understanding of the operation and partly to the development of surgical skills, better suture (stitching) materials and things like headlights and magnifying glasses. Huge advances have been made in understanding how a body copes with the stress of major open heart surgery, particularly children’s bodies. Intensive care units have become extremely sophisticated. These days, most babies and children having heart surgery survive. Usually children need more surgery as they grow, so increasingly we have adult patients returning for congenital heart surgery.

Tissue donation just as important as organs

There is a large range of congenital heart defects. In some cases holes need to be closed. In others, narrow arteries need to be widened. Patches are used for this - there are different types. Some are made from special cloth materials. Some are made from the skin sack found round the heart of a cow or pig. These are treated so they can be used in humans. The best and most suitable material is taken from a human body. It is called a ‘homograft’. This is a very important area of organ and tissue donation which not many people know about.

Human tissue is the perfect thickness and shape for patches; especially for narrowed arteries. Sometimes the artery is completely missing, so we can use the artery, including its valve. Valves from adults can be used in children. Taking the valve and artery is not a true transplant because the tissue is not alive. Tissues do not need to be blood group matched and can be taken up to 48 hours after a person’s death. The valves are removed by specially trained people based in a few specialist centres around the country. The valves are sterilised with antibiotics; then frozen. They are kept in very cold freezers until needed. They can be stored up to 6 months.

First heart transplant in the world took place in 1967

In 1967, Professor Barnard performed the first heart transplant in South Africa. The first patient did not survive very long for a number of reasons: it was known that the body would try to reject the new heart, but doctors did not really understand the process. Special drugs needed to prevent rejection were not available at that time. It was not for another 22 years that Cyclosporin, the specific anti-rejection drug, was discovered.

There was much discussion of important questions relevant to transplant surgery. Questions such as: ‘When does death occur?’ ‘Is it when the heart stops beating? ... or when the brain stem stops functioning?’ The brain stem is the part of the brain which connects it to the rest of the body. When it dies there is no hope of the patient recovering.

At the time these questions were being asked, intensive care units were being developed. It became possible to keep a patient’s body alive, on a life support machine, long after it was obvious their brain had died. Carefully considered tests for ‘brain stem death’ were being agreed so medical staff could know when to stop trying to save patients who could never recover. The criteria for determining brain stem death are very strict. No patient has ever recovered after the criteria have been met.... (despite occasional suggestions to the contrary in the media).

'Beating heart' donors

Signals from the brain stem maintain the circulation of blood through the body. The blood flushes all the body’s organs and tissues and helps keep them working. After brain stem death, there are no more brain signals to control the natural blood flow, so control over the body functions quickly breaks down.

When the first transplants were carried out in the late 1960s, the concept of brain stem death had not been thought through. Transplant teams had to wait until a donor’s heart actually stopped before they could remove it for transplantation. By then the donor heart was badly damaged and often did not work long in the recipient. By using criteria for determining brain stem death, it became possible to have a ‘beating heart donor’.

Legally, a patient’s death is recorded as the time when the brain stem tests are done. The decision to withdraw treatment is made in conjunction with the patient’s family. This is the time the question of organ donation arises. At present in the UK the relatives must give permission for organ donation.

Better results than ever before

Transplantation of the heart, lungs, liver and kidneys are now standard procedures with good results. Research into pancreatic transplants for diabetic patients is continuing and results are improving. Occasionally the small bowel is used for transplantation. Corneas – the outer eye lining – have long been transplanted with great success. The cornea can be taken after blood circulation has stopped. Valves and arteries from the heart can be removed up to 48 hours after death.

Organs for transplantation need to be removed while blood is still circulating. It requires great skill from intensive care teams to maintain the donor’s circulation after brain stem death because all the body’s control systems of circulation are lost.

The donor operation is carried out in an operating theatre. It is important families of donors know the patient is treated with dignity and respect by the surgical teams involved. One team is involved in removing the heart and lungs while a second team removes the organs in the abdomen. The organs are preserved with a special fluid, then packed in ice.

Different organs last for varying times. The heart is the most sensitive organ. We aim to have the new heart in the recipient within 4 hours – hence the drama of flashing blue lights and sirens when the donor heart is being transferred to the recipient’s hospital. The liver will tolerate up to 18 hours without a circulation; kidneys up to 48 hours.

Heart transplant surgery has become a normal procedure

For the heart surgeon, heart transplant operations are relatively straightforward. There are 2 collecting chambers, called atria, and 2 main arteries (1 for the body and 1 for the lungs) to connect to the recipient. This takes about one hour, although the total operation time will be 5 or 6 hours.

Heart transplantation can be performed at any age – the youngest we have done was 3 months old. Some children need a transplant because they have developed a ‘cardiomyopathy’ – their heart muscle has become tired and their heart cannot pump very well. We are not sure but we think this is due to infection with a particular type of rare virus. Others need a transplant because they were born with a heart defect – some of the operations we do, to try and fix things, do not last forever. The scarring around the heart from previous operations can make the transplant longer and more difficult. Sometimes children get worse while they are waiting for a new heart. We have to put them on a special heart-lung machine (ECMO or BiVAD) – then we hope to get a heart quickly. They cannot stay on these machines for long.

When we are offered a heart for transplantation we have to match blood group, size and body weight. When the heart is sick it usually becomes very enlarged, so the space for the new heart is bigger. This means we can use a heart from a small adult in an older child, and from an older child in a small child.

Transforming lives through donation

Nowadays, over 90% of heart transplant patients survive the operation and enjoy a good quality of life for many years. But we do not forget that behind every transplant there is a tragedy – the unexpected death of someone dear.

It takes courage for the family to give consent to organ donation but in doing so, hope comes from despair.

Leslie Hamilton, Consultant Paediatric Cardiac Surgeon

(Reproduced by kind permission of Sue Cansdale who compiled and wrote "Transforming Lives through organ and tissue donation" - see the website www.legacyoflife.org.uk to find out how you can buy a copy and more)