Being a paediatric cardiologist at Great Ormond Street Hospital involves me caring for children with complex congenital heart problems. I made a prenatal diagnosis on one baby, whose left side of their heart was small. When that happens it means the blood vessel coming out of the heart and supplying the body is likely to be narrow. In some cases the growth of the left hand side of the heart during the rest of the pregnancy will keep pace with the baby's growth and it's possible to use the left hand side of the heart to pump blood round the body after birth, when the narrowed blood vessel is surgically repaired. However, this growth doesn't always keep pace, and we then have to perform complex surgery to use both the right and the left pumping chambers together to pump blood around the body simultaneously, which we call a single ventricle circulation.

At 17 weeks I discussed with the mother the fact that this baby was going to require surgical attention in the immediate period after birth. The choice of surgery makes a big difference to the baby's long-term survival and ability to lead a healthy and normal life. A baby with a single ventricle circulation will be limited in its exercise capacity and is almost certain to have a shorter lifespan.

In this particular case I felt that it was possible that the left hand side of the heart was going to be big enough, but by the end of the pregnancy I was still undecided. When baby was born, the left hand side of the heart wasn't big enough based on conventional measurements. The parents understood the implications of a small left ventricle. Their aspirations for their baby, and all the other features of the left ventricle in this baby's heart, convinced me to go for broke and avoid a single ventricle circulation. But I still had to persuade my surgical colleagues, who would do the operation, that this was the right decision. With some discussion, they agreed.

The baby had a successful operation and came back into the intensive care unit but we still needed the left hand side of the heart to grow over the next three to six months in order for this strategy to work.

Although the baby's progress was slow, and parental anxiety high, I still felt that with time the baby's heart would cope, so stuck to my convictions. That baby's coming to see me this week and is now three. Every time I see them I think I'm lucky that we made the decision we did.

If I'd got it wrong then I'd have committed the baby to having a shortened lifespan and a different quality of life.

The official F1™ Party, sponsored by Santander, in aid of Great Ormond Street Hospital Children's Charity, will be held on 6 July, to raise vital funds for the new Heart and Lung Centre. For tickets, please email