DOWN SYNDROME AND HEART SURGERY

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Freddie Wood explains in detail the various heart conditions that can affect those with Down Syndrome.

I have been very privileged over three decades of professional life to treat many babies and children with Down Syndrome.

Down Syndrome occurs approximately one in every 650-1,000 live births. Congenital heart disease occurs in approximately 40% of these individuals, predominantly ‘pink’ as against ‘blue’ ‘Pink’ congenital heart disease occurs from a left to right shunt, when there is a communication from the high (left) pressure side of the heart, to lower (right) pressure side. This then results in excessive flow through the lungs compared to the systemic circulation. Because of this excessive flow through the lungs, the babies frequently develop high-output heart failure, failure to thrive, get repeated respiratory tract infections and rapidly develop pulmonary hypertension. This is a condition where the blood vessels of the lungs react to the excessive blood flow and attempt to control it by going into spasm which, after a period of time, becomes permanent. When this occurs, the babies come out of heart failure and start to thrive, but their overall life expectancy is then reduced significantly to between 15 and 25 years approximately—maybe a little longer with present medication.

Children with Down Syndrome develop pulmonary hypertension more quickly than children in the general population, usually at around 12-15 months, and it can become permanent from 18 months (generally). As a consequence, these babies need surgery/intervention anywhere from 4 months of age to 1 year, in order for them to have the same life expectancy as children with Down Syndrome who do not have heart disease.

The conditions which cause this are Patent Ductus Arteriosus (PDA), Ventricular Septal Defect (VSD), Partial Atrio Ventriculo Septal Defect (PAVSD) and Common Atrio Ventriculo Septal Defect (CAVSD).

PDA can be very effectively treated in the catheter Lab by device closure or by surgery. Both are equally effective and safe. Surgery is now reserved for babies weighing less than 10 kgs, or who have a very large duct that requires surgical division. Once treated, it is rare for any other intervention to be required.

VSD requires open-heart surgery, usually between 6 months and 1 year. The VSD (hole between pumping chambers) is patched with a cloth (usually dacron) operating through the atrium when the heart is stopped. It is successful in 99% of babies and they survive to become normal. 1 % may require a pacemaker. No further surgery is usually necessary.

Partial AVSD is a more complex defect made up of a hole (ASD) between the collecting chambers (atria) and a cleft left atrio ventricular valve (mitral). Again, this is an open-heart operation., The ASD is patched, usually with pericardium from the sac outside the heart, and the valve cleft is sown up/repaired. This again is a very safe operation, with 99% of babies surviving. 1% may need a pacemaker at some stage. Some 2-5 % may require a reoperation either for patch dehiscence or continued leak of the mitral valve.

Lastly, the most complex of the heart conditions which infants with Down Syndrome may have is complete AVSD. This involves an egg-shaped defect at the base of the heart, resulting in an ASD, VSD all as on hole and clefts in the left AV (mitral) and right AV (tricuspid) valves making the valves ‘common’. All of this results in a ‘torrential’ left-to-right shunt and consequent heart failure. This defect is more common among children with Down Syndrome than in the general population. Indeed, it is the commonest congenital heart defect in Down Syndrome. Repairing the defect requires quite complex open-heart surgery. The left AV (mitral) valve has to be reconstructed, the VSD patched, the ASD patched and, frequently, the right AV (tricuspid) valve repaired. The surgeon is operating close to the conduction (pacemaker). The survival rate for this procedure is approximately 96-97%. A pacemaker may be necessary in 2-3 % of those affected. Reoperation for a leaking mitral valve is required in 5-6 % of cases, over 3-10 years. The vast majority recover very well and have a life expectancy of 50- 65 years. It is not known what exactly will happen with the left AV (mitral) valve, as it is quite mis-shapen compared to normal. There is some evidence that these valves may need to be replaced when the individual reaches their late twenties or early forties, however this may only become clear in the next 10-15 years.

It has been most rewarding that all the children who have had surgery have reached their milestones, as if they had no heart disease. Indeed, 30 years ago, this surgery was not offered to babies with Down Syndrome because of what was considered very high risk. Having pioneered it in the 1980s, it is very rewarding to see so many thriving, from a cardiac point of view, and that it is now standard to offer this surgical treatment to all children with Down Syndrome. Lastly, I have found it remarkable how the boys and girls with Down Syndrome have become the centre of their family’s life, binding everyone together.

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