What the doctors will do

Tony Blair's problem - atrial flutter - is a common disorder which causes the heartbeat to race.

On the first occasion it can seem scarily close to a heart attack but, after it has been diagnosed, subsequent episodes are more of an irritation.

However, the possible complication is that it can cause clusters of blood clots in the right atrium, an upper heart chamber, which can break off and cause heart attacks or strokes.

The condition can be controlled by drugs such as beta-blockers, but they can have unpleasant side effects. Consultant cardiologist Dr Duncan Dymond, of St Bartholomew's Hospital, London said ablation therapy would be the treatment of choice for a man in early middle age.

He said: 'Medication controls the condition but ablation therapy can cure it. There is a good chance of a completely successful outcome in 90 per cent of cases.'

Ablation therapy is a treatment using high-frequency radiation to destroy part of the abnormal electrical circuit that has been set up in the upper heart chamber. The cause is a mild electrical defect that develops over time or patients may have been born with.

Dr Dymond said: 'It's like a Grand Prix circuit in which there is an electrical surge around the chamber of around 300 beats a minute which races for a short period of time. The aim of radio frequency ablation is to destroy part of this large electrical circuit.'

The procedure is usually carried out under local anaesthetic. A catheter is threaded up through a vein possibly through a leg or the neck to the right atrium where four electrodes are attached which map out the pattern of the abnormal circuit.

Once the area of problem has been identified, a surge of radiation is used to 'fry' it. The procedure is quick and the risks are slight. Complications can include the heart or blood vessel becoming perforated or damaged.

If all goes to plan, Mr Blair will be back at his desk within days.