The mother of a 16-year-old stabbing victim today told how her son was “clinically dead” when doctors carried out life-saving open-heart surgery and a blood transfusion at the roadside.

The GCSE student, named only as Rayan, was stabbed in the chest as he walked through a park in north-west London early this year. Paramedics were driving him to St Mary’s Hospital in Paddington when he “flatlined”.

A team of night doctors from London’s Air Ambulance, which now carries blood to treat major traumas, intercepted them. When doctors began their roadside surgery, there was virtually no blood left in his heart.

London’s Air Ambulance lead clinician Dr Anne Weaver said: “The monitor was a flat line. He had no pulse, there were no signs of life. As we gave him the blood, his heart filled up and his colour changed.” Rayan was given drugs to keep him asleep and he was taken to St Mary’s, where he stayed for a week. Dr Weaver said: “To have Rayan here today and see him making a full recovery and get back to school is what our work is really all about.”

Rayan’s mother spoke on condition their personal details and the location of the attack would not be published, as they still fear reprisals. She said:

“It is so distressing to think he was clinically dead. To be able to give blood transfusions and do open heart surgery at the roadside, it’s just incredible. They are angels for me and my family. They saved my son’s life.”

London’s Air Ambulance, based at the Royal London in Whitechapel, last year became the first service of its kind in the UK to carry blood and administer transfusions at the scene to patients suffering from “catastrophic bleeding”. Rayan is one of about 100 patients to have received a roadside transfusion. Most were victims of road crashes, stabbings or shootings, and nearly half suffered traumatic cardiac arrest and needed their heart restarted.

Detectives said today the case is still under investigation.