Tetralogy of Fallot is a serious heart abnormality in which there are two main problems –
1. There is a narrowing in the right sided pumping chamber of the heart (the right ventricle) just below the outlet valve (the pulmonary valve) which lets blood pass from the heart to the artery which feeds the lungs with blood (the pulmonary artery). The outlet valve itself is also usually narrowed.
2. There is a large hole (ventricular septal defect or VSD) between the two main pumping chambers (ventricles) of the heart.
In the normal circulation, blood passes through the lungs to collect oxygen from the air. In babies with tetralogy the narrowing in the heart causes blood flow to the lungs to be reduced, making the blood oxygen level low. This makes the baby (particularly the lips and hands) appear blue. How blue the baby looks depends on how severe the narrowing in the heart is; some babies appear pink or are just slightly blue when they cry but others may appear blue all the time. Some children with tetralogy may have attacks where they become suddenly very blue or very pale or floppy or faint. These are known as "hypercyanotic attacks" or are sometimes called "spells". If your child has attacks like this you should contact your hospital immediately as the attacks can be very serious and may even be lifethreatening.
Some children with tetralogy have other abnormalities. The commonest of these is a genetic abnormality, where a small part of one chromosome is missing. This abnormality is called "22q11 deletion" (or "Catch22"). Although some children with 22q11 deletion grow and develop normally, some will have learning or speech difficulties and if your child has 22q11 deletion it is important that his or her development is monitored so that help can be given early if necessary. A blood test to check for this abnormality is usually done, but it may take some weeks for the result to come back.
Only a simple ultrasound scan ("echo") is required at first, but before plans for surgery are made most children need to undergo a test called cardiac catheterisation. This is usually performed when the child weighs over 6kg and involves putting a small tube (catheter) in the vein (sometimes in the artery too) at the top of the leg and feeding it up into the heart. A special type of dye which shows up on an X-ray machine is injected through the catheter, allowing us to take detailed X-ray pictures of the heart and arteries. The test is usually done under general anaesthetic and usually involves one night’s stay in hospital. There is a very small risk (around 1 in 300) of serious complications or even death during the catheter test.
Most babies do not need any special treatment to start with, but major surgery is necessary later on because most children will die before reaching adult life unless they are treated. Surgery is normally planned before school age but the type and timing of treatment depends very much on how blue an individual baby becomes as well as how well the pulmonary arteries (the lung arteries) grow. If the pulmonary arteries do not grow well it may be necessary to perform a "shunt" operation to improve the blood supply to the lungs before we can consider major surgery to repair the heart. If the arteries have grown well we usually plan a single operation to close the hole (VSD) by sewing a patch over it and to open up the narrowing (pulmonary stenosis) in the heart. If there are also narrowings in the pulmonary arteries these can be treated at the same time by sewing a patch into the wall of the artery. This is often referred to as "corrective" surgery, but it never makes the heart completely normal.
Risks of treatment
All heart operations are very serious and carry some risk of death or major complications such as permanent brain damage, kidney damage or lung complications such as pneumonia. For shunt operations the risk of a baby dying is small (about 1 in 100) and the risk of brain damage is also small (probably around 1 in 100). At the major repair operation the risk of dying is about 1 in 25 and the risk of brain damage is about 1 in 100. There is also a small risk (around 1 in 100) of the heart’s electrical system being damaged at operation; if this happens the child’s heart rate will be much slower than normal and a further operation is required to implant a pacemaker to make the heart beat faster.
After the operation
Most children are in hospital for about a week after their operation, although it may be longer than this if there are complications. Most children have medicines to take at home after leaving hospital but these are usually only necessary for a month or so. Visits to the outpatient clinic will be necessary after the operation.
The long term future
Most patients with repaired tetralogy will lead normal active lives after their operation and the only limitation we usually recommend is to avoid competitive sport or physical activities which involve really hard exercise (such as playing squash). All patients who have had tetralogy repair operations have an abnormal pulmonary valve. This rarely needs treatment but occasionally further surgery is necessary in older children and adults to replace the valve. Even many years after apparently successful surgery new problems may arise which require treatment. One of the commonest late problems is the development of abnormal heart rhythms. These can usually be treated, but can be serious and can even rarely be fatal, so regular review in outpatients by a specialist is very important even if the patient appears well.
General advice for the future
Most children with major heart disease cannot manage as much physical exercise as a normal child, but we do not usually stop children with heart disease from doing exercise, as they usually know best themselves when to stop and rest, but it is probably best to avoid really hard physical exercise even after a successful operation. All patients with tetralogy will be at risk of infection in the heart (called endocarditis), both before and
after surgery. Such infections may be caused by infections of the teeth or gums or even by routine treatment at the dentist. It is important to visit the dentist regularly and to remind the dentist at each visit of the heart abnormality. You will be given an information card to help you with this. Ear or body piercing and tattooing are best avoided as they also carry a small risk of infection which may spread to the heart.
How to interpret the survival funnel plots
These graphs show the national average survival after specific procedures for treating congenital heart disease. The national average is shown as a horizontal grey line. Two control limits are shown; a warning limit (Green line, 98%) and an alert limit ( Red line 99.5%). Unit performances are shown as identifiable coloured symbols. If a unit's symbol is above the green line then the performance is no different from the national average. If a unit’s survival rate is below the warning limit, their performance will be closely monitored in subsequent years. If a unit’s survival rate is below the alert limit, an investigation into possible reasons and remedial actions will be launched by the appropriate professional and regulatory bodies.