I haven’t slept in twenty hours, but my mind is alpine clear as adrenaline courses through my system. I get the same rush when I ski a black mogul field in a blinding snowstorm, operating on pure instinct. One miscalculation, and the day is lost.

But I don’t miscalculate.

The perfusionist gives me a brief nod across the table.

‘We’re good,’ she says.

It’s her job to run the cardiopulmonary bypass pump while I operate. My patient has an aortic aneurysm: a bulge in the main blood vessel that carries blood from the heart to the rest of the body. Arteries usually have strong, thick walls. But sometimes the force of blood constantly pushing against an area with weakness can make them swell. The result is a balloon-like bulge: an aneurysm. When it bursts, it causes huge internal bleeding and is usually fatal.

The woman on the table is unlucky: she’s young and a non-smoker, and nearly two-thirds of aneurysms happen to men. But she’s six months pregnant, which is probably what caused it to rupture. Until it happened, she wouldn’t have known it was even there.

The woman on the table is lucky: she has me.

I work quickly and efficiently to save her life. My surgical team know me well, and anticipate my needs effectively and without drama. Once the heart has been repaired, I put the sternum back together, using plates and screws to hold the breastbone and ribs in place as they heal.

Finally I close the incision with three layers: no suture material is visible on or above the skin. I use vicryl sutures for the first two layers and monocryl sutures for below the outside layer of the skin. Both are absorbed by the body within two or three months. My aim is to minimise the trauma to the chest to allow my patient to recuperate faster. I have the lowest mortality rate of any doctor in the hospital, and one of the lowest of any heart surgeon in the country. I intend to keep it that way.

My surgical registrar catches me as I change my scrubs.

‘Ms Lennox, do you have a moment to talk to the husband?’ she says. ‘He’s very anxious.’

Someone will have kept my patient’s family apprised of her progress, but relatives always want to speak to the surgeon. We’re the closest they get to talking to God.

I follow the registrar to the family waiting room. The husband is at least a decade older than his wife, and a good three stone overweight. Nicotine stains his fingers. He should have been the one on my operating table.

He grabs at my arm. ‘Dr Lennox, please, how is she?’

‘It’s Ms Lennox,’ my registrar corrects.