HE is his parents' little miracle - and he would not have survived to celebrate his first birthday yesterday without the skill of staff at the Wessex Cardiac Unit.

When Aaron Drew was born in a text-book delivery at Poole Hospital on October 25 last year, there was no sign that anything might be wrong. He weighed 7lbs 15.5ozs and looked perfect.

His birth was a joyful occasion for his parents Barrie and Tracy, of West Parley, and for their 10-year-old son Matthew.

"All he ever wanted was a brother or sister, but I had been told I might not be able to ever have another child. I had a borderline ovarian tumour in 1999," said Tracy, 38.

Just two days after the birth, she and 41-year-old Barrie went home with their new baby but Tracy noticed Aaron's hands were very cold. The family's GP sent him for checks at Poole Hospital, where doctors referred him on to the paediatric cardiac unit at Southampton General Hospital.

At the unit, specialists discovered that the great arteries in Aaron's heart were the wrong way round.

Normally, the pulmonary artery carries oxygen-depleted blood from the right lower chamber (ventricle) of the heart to the lungs, while the aorta carries oxygenated blood from the left ventricle to the body.

But because Aaron's two main arteries were transposed, oxygen-depleted blood was being pumped around his body, while the oxygen-rich blood was being recirculated around his lungs.

Babies born with such a defect can survive for a short time because of a small opening between the upper chambers of the heart that is normally present at birth.

This opening allows a small amount of oxygenated blood from the lungs to cross from the left upper chamber of the heart (atrium) to the right, then via the right ventricle and aorta to the body.

But without urgent open-heart surgery to reconnect his tiny arteries - less than a millimetre in diameter - Aaron would have died. He underwent the three-hour operation when he was just a week old.

"He was christened on the morning of the operation. It was frightening. We didn't know if we would see him again," said Tracy.

"It was probably the lowest point of our lives, but the staff were so fantastic. I just can't tell people how wonderful they are. I'll never forget the whole thing. It's very vivid in my mind still - it brings a lump to my throat to think about it."

After the operation, Tracy was struck by the change in Aaron's colour. "He was pink. I hadn't realised that he wasn't the right colour before." After only two weeks in hospital, Aaron was allowed home again.

"He had a massive operation in the first few days of his life, but afterwards he didn't look back at all. He's really gone from strength to strength," said Tracy.

As she watched her precious baby grow, the only cloud was continuing concern about Tracy's own health. In April, she underwent a hysterectomy. "It's been a bit traumatic, but you have to brush yourself down and get on with it," she said.

"Our health visitor has just done Aaron's one year check and he's perfectly normal in every way. He weighs 21lbs 7ozs, eats very well, he's crawling all over the place and he's into everything.

"I know I'm his mum, but he's just beautiful and he's such a good boy when we go to hospital. He's very, very special.

"Our friends and family have been incredibly supportive. One friend had twins on the day of the operation, so the girls' birthday will always be a reminder."

Aaron shared his birthday party with his brother, who recently turned 11. And there was further cause to celebrate because Tracy and Barrie have been told Aaron does not need another check-up at Southampton Hospital for a year.

"He's hale and hearty. After what he's been through, he's just brilliant," said Tracy. "I can't sing the praises of the unit enough - it's amazing what they can do."