Health: They said my baby's heart was failing: Cardiac irregularities in foetuses are serious, but they can survive if the danger signs are spotted quickly. Janet Morgan reports on a success story

When Angela Sangster went to her midwife four years ago for a routine scan six months into her pregnancy, she had no cause for alarm. An earlier scan had been normal and her three previous pregnancies had been healthy.

'The midwife listened to the baby's heart rate. It was on a speaker so I could hear it as well. At first, we thought the instrument was faulty because it sounded fast but irregular. But another one was the same.'

Mrs Sangster was rushed to Northampton General Hospital for an ultrasound scan which revealed that her unborn baby's heart was functioning abnormally. He was in the early stages of heart failure and might not survive the night, she was told. The doctors arranged to have Mrs Sangster transferred to the foetal cardiology unit at Guy's Hospital, London, the next day.

Mrs Sangster was frightened: 'When I was travelling to Guy's, the whole time I was willing the baby to move. Every time I felt it move I knew it was still alive.'

At Guy's, she received flecainide, a drug more commonly used to treat irregular heart rhythms in adults. Her blood was tested regularly to ensure there was enough medication to cross the placenta but not too much to cause damage.

The Guy's unit, led by the consultant Dr Gurleen Sharland, has pioneered the treatment of unborn babies with heart problems by giving medication to the mother. The unit uses two drugs, flecainide and digoxin, and the results are promising, nearly doubling the survival rate in these vulnerable pregnancies. Dr Sharland says there have been no complications or resultant birth defects to date.

At Guy's, the medication is usually continued into the first year of life, allowing the baby to 'grow out' of it. 'We have found in some of the babies that, although we manage to control the arrhythmia in the womb, a few weeks after birth the rhythm disturbance comes back and it can be harder to control,' says Dr Sharland.

Irregular heartbeats, or heart arrhythmias, are rare in unborn babies, only about one or two in every 1,000 pregnancies. But without treatment the chances of survival are poor. 'Some of the babies will die in the womb, some will deliver prematurely and die because of complications of prematurity,' Dr Sharland says. 'Others die within the first few weeks of birth, unable to survive life outside the womb.'

An abnormal heart rate in a foetus damages the development of the heart, eventually affecting its ability to pump blood effectively. The beats in a normal foetal heart range between 120 and 160 beats per minute (bpm); babies with greater than 200bpm are considered at risk. Mrs Sangster's unborn baby had a rate of 260bpm when she was admitted to Guy's.

The unit has seen more than 100 cases in eight years. Dr Sharland says babies whose arrhythmia can be controlled while still in the womb will be normal after birth. Those whose hearts have started to fail, such as Mrs Sangster's, are more serious but can be treated successfully if caught early enough.

'If we have been able to control the rhythm before the baby is born, it will have a 90 per cent chance of survival. The ones we have not been able to control before birth will have only a 50 per cent chance,' Dr Sharland says. But unborn babies can only be treated if the condition is spotted in antenatal checks. The only sign a woman might have that her baby has heart trouble is reduced foetal movement, or a feeling of being bloated as the baby retains fluid. Mrs Sangster felt fine when she went for her scheduled antenatal check-up, but a day later she looked nine months' pregnant rather than six.

Other hospitals in Britain are beginning to imitate the work at Guy's. 'Some centres, particularly if they are a long way from Guy's, will ask for advice over the telephone,' Dr Sharland says.

While she understands the desire to be treated locally, telephone consultation worries her. 'It has been one of my main concerns whether or not these women are properly evaluated. You need to have a bit of foetal cardiology training to assess what type of problem it is,' she explains.

Mrs Sangster was discharged from Guy's after two weeks, when her baby's heart rate had stabilised at around 160bpm. She was sent home to Northampton to be managed by her doctor and midwife.

Luke Sangster was born two weeks early by Caesarean section on 23 March 1990, weighing seven pounds. An electrocardiogram of his heartbeat was normal.

'I feel so lucky I went to the midwife that day, even though I felt fine,' Mrs Sangster says. 'If I hadn't gone, I might have lost Luke.'

(Photograph omitted)