Congenital heart disease

In roughly one child in a hundred the heart forms differently from the usual pattern. It is the commonest of all birth defects, and the general name covers very different realities: from a tiny hole that will close by itself to a defect that has to be operated on in the first days of life. The good news is that the picture has changed radically over recent decades, and today the great majority of these children reach adulthood. The bad news is that "it has been fixed" almost never means "cured for good": follow-up lasts a lifetime.

How the heart is built and what can go wrong in it

The heart has four chambers. The two atria collect blood: the right one from the body's veins, the left one from the lungs. The two ventricles push it out: the right sends blood to the lungs to take up oxygen, the left sends it into the aorta and on around the body. Between the chambers and at their exits sit four valves that let blood through in one direction only. All of this comes together in the first weeks of pregnancy, as the heart turns from a simple tube into a four-chambered pump; a fault at that stage is what produces a defect.

The faults fall into a few groups. There are holes in the wall between chambers, what people call a hole in the heart: atrial and ventricular septal defects. There are narrowings of the pulmonary valve, the aortic valve or the aorta itself, which is coarctation. There are vessels plumbed into the wrong place: transposition of the great arteries, in which the aorta and the pulmonary artery are swapped, or anomalous pulmonary venous drainage, in which the veins from the lungs empty into the right side instead of the left. There are underdeveloped chambers, so that in practice one ventricle works instead of two, a group that includes hypoplastic left heart syndrome and tricuspid atresia. Separately there are combinations of several defects at once, the best known of which is tetralogy of Fallot.

Then there is the patent ductus arteriosus. Before birth this vessel is needed: the lungs are not breathing and blood bypasses them through it, and after the first breaths the duct should close. If it stays open, extra blood goes to the lungs and the heart has to work for two. With some severe defects the reverse is true: it is precisely the open duct that keeps a newborn alive in the first days, and a drug is given to stop it closing.

Why it happens

In most cases no specific cause can be identified, and parents deserve to hear that plainly: there is almost never anybody's mistake behind it. Certain circumstances are nevertheless known to raise the likelihood.

• Genetic conditions. About half of children with Down's syndrome have a heart defect, most often a septal one. Defects are also common in Turner and Noonan syndromes and in the deletion on chromosome twenty-two. Sometimes a particular defect runs in a family with no syndrome attached.
• Diabetes in the mother. The risk is higher with type 1 and type 2 diabetes when blood sugar is poorly controlled in the first weeks of pregnancy, which is exactly when the heart is forming. It does not apply to gestational diabetes, which appears in the second half and resolves after the birth.
• Infections. Rubella caught in the first two or three months of pregnancy is the classic cause. Influenza in the first trimester is also linked to increased risk.
• Alcohol. No safe amount in pregnancy has been established; with regular drinking septal defects are noticeably more frequent.
• Certain medicines. Above all valproate, used for epilepsy, and vitamin A derivatives for severe acne, including the ones applied to the skin. Anti-inflammatory painkillers in the second half of pregnancy can affect the baby's ductus arteriosus and kidneys.
• Untreated phenylketonuria in the mother and work with organic solvents: paints, varnishes, degreasers and nail polish remover.

None of these works on the principle that exposure guarantees a defect: they shift the odds, they do not pass sentence.

Signs that show in a child

Symptoms depend on which defect is involved. Mild ones produce nothing noticeable and turn up by chance, sometimes in adulthood. More serious ones show early:

• a blue tinge to the lips, tongue and skin; on brown and black skin look for it inside the mouth, on the nail beds and on the palms;
• fast breathing at rest, the spaces between the ribs pulling in, grunting on breathing out;
• tiredness and breathlessness during feeds: the baby sucks in short bursts, sweats, cannot manage a full feed and gains weight slowly;
• a racing heartbeat;
• puffy eyelids, swollen feet and legs, a distended abdomen;
• listlessness, pallor, a baby who sleeps unusually long and eats little.

In older children and adults other things come to the fore: breathlessness and rapid tiredness with exertion that peers manage easily, palpitations and irregular beats, dizziness, swollen ankles. A separate warning sign is fainting during physical exertion, as opposed to after standing a long time in a stuffy room; that always needs discussing with a doctor.

When it cannot wait until morning

Some defects give no sign in the maternity unit and declare themselves in the first or second week of life, when the ductus arteriosus closes. The situation can deteriorate within hours. Call the emergency services if a baby has:

• lips, tongue or skin that have turned blue or grey and do not recover;
• fast, noisy breathing with the ribs drawing in and the nostrils flaring, or pauses in breathing;
• floppiness, difficulty waking, an absence of the usual responses;
• refusal of several feeds in a row, or heavy sweating while feeding;
• cold, clammy, pale mottled skin with hands and feet colder than the trunk;
• a temperature below normal or, conversely, a fever in the first weeks of life.

In an older child or an adult with a known defect, chest pain, fainting on exertion, sudden severe breathlessness, a suddenly racing or irregular heartbeat, and prolonged unexplained fever with chills and sweats all count as urgent, because the last of these can be the start of an infection of the heart lining.

How a defect is found

Many defects are visible before birth. At the screening ultrasound the heart is examined too; where there is a suspicion, a family history or an increased risk, a separate detailed scan of the baby's heart is done at around eighteen to twenty-two weeks. It does not catch everything: small defects and some narrowings cannot be seen before delivery.

After birth the heart is listened to at the newborn examination. A murmur on its own settles nothing: murmurs are common in healthy babies, and some severe defects produce no murmur at all. Far more useful is measuring the oxygen level with a sensor on a hand and a foot, a simple painless check that picks up defects invisible to the eye and inaudible to the ear.

The main confirming test is an ultrasound scan of the heart, which shows the structure of the chambers, valves and vessels and the direction of blood flow. It is supplemented by an electrocardiogram, recording the heart's electrical activity, and a chest X-ray, which shows the size of the heart and whether the lungs are overloaded with blood. When exact pressure figures inside the chambers and vessels are needed, cardiac catheterisation is performed: a thin tube is passed through a vessel in the arm, neck or groin and guided to the heart under X-ray, with dye injected if required. It is done under anaesthesia, and in children usually under general anaesthesia.

What is done about a defect

Treatment depends entirely on which defect it is. Small holes in the septum often close by themselves in the first years; they simply get watched and have no effect on health. Moderate valve narrowings can also go for years without needing anything.

When intervention is needed there are two routes. The first is through a catheter, without opening the chest: a narrowed valve or vessel is stretched with a balloon, a mesh tube is left inside if appropriate, a hole in the septum is plugged with a purpose-made device, and an open duct is blocked with a coil. All that remains afterwards is the mark of a puncture in the groin, and recovery takes days. The second route is open heart surgery, used to close large defects, replace valves, put swapped arteries back where they belong and redirect veins that drain in the wrong place.

The most complex defects, where only one ventricle really works, are treated in several stages over the first years of life: the circulation is rebuilt step by step so that blood reaches the lungs bypassing the underdeveloped chamber. This is not the restoration of a normal heart but a workable detour, and such patients need lifelong follow-up at a specialist centre.

Medicines play a supporting role: they clear fluid and ease breathing, steady the rhythm and stabilise a child before an operation. In newborns with severe defects a particular drug keeps the ductus arteriosus open until the time comes to intervene.

What can follow later

Even after a successful operation, a person with a congenital heart defect keeps a raised risk of several problems, and it is worth knowing about them in advance because most are picked up at routine check-ups.

• Rhythm disturbances. Over time the heart may beat too slowly, too fast or irregularly; this is managed with drugs, a pacemaker, or by burning the focus through a catheter.
• Heart failure. It shows as breathlessness on exertion and at rest, swelling of the legs and abdomen, and heavy fatigue.
• Infective endocarditis. An infection of the heart's inner lining and valves: bacteria from the gums or skin enter the blood and settle there. It brings prolonged fever, chills, night sweats, weight loss and aching muscles, and is treated only in hospital.
• Raised pressure in the lung vessels. This causes breathlessness, fatigue, dizziness and faints, and chest pain.
• Frequent chest infections in children, and slow gain in weight and height.
• Learning difficulties in children with complex defects, affecting memory, attention, planning and language. Teachers and psychologists work on this.
• Blood clots that may block vessels in the lungs or the brain; with some defects blood-thinning drugs are prescribed.

Living with a heart defect: what matters years ahead

Follow-up does not end with childhood. An adult needs a cardiologist who deals specifically with this group of patients, and scheduled reviews even when nothing is troubling them: a valve fitted in childhood wears out over the years and the rhythm changes without announcing itself.

Teeth have a direct bearing on the heart: regular brushing, treating decay and going to the dentist are real prevention against endocarditis. The dentist should be told about the defect, and before certain procedures an antibiotic is prescribed in some cases. Tattoos and piercings are best avoided for the same reason.

Physical activity is no longer forbidden. The old approach of excusing these children from everything is now regarded as harmful: moving improves both fitness and how a person sees themselves. But the level of exertion and the permitted sports are set by the cardiologist, because with some defects competitive and heavy strength work really is dangerous.

Pregnancy in women with a congenital heart defect goes well in most cases, though the load on the heart rises considerably. It should be discussed with a cardiologist before conception: medication may need changing and a maternity unit with the right experience choosing. The baby of such a mother is usually given a separate scan of the heart at around twenty weeks.

As for prevention, nobody can offer guarantees, but the risk can be lowered: check rubella immunity and have a flu vaccination before pregnancy, give up alcohol, keep diabetes controlled, go through every medicine being taken with a doctor including over-the-counter and herbal ones, avoid solvents, and take folic acid from the outset, usually four hundred micrograms a day for the first twelve weeks, with a different dose prescribed by a doctor in certain conditions.

Online consultation

A remote appointment suits the questions that pile up between reviews. The doctor will explain what the wording of an ultrasound report means and how serious the defect found actually is, help work out which specialist to see and how urgently, and assess whether a murmur heard in a child needs attention. Online is also the sensible place to discuss permitted exertion, preparing for dental treatment, planning a pregnancy, how well medicines are tolerated and which signs to watch for at home. Everything listed above as urgent cannot be handled through a screen: that calls for emergency services or an immediate face-to-face examination.

This material is for information only and does not replace medical advice.