The 77-year-old Israeli Prime Minister will stay overnight at the Hadassah hospital in Jerusalem after the 30-minute procedure to introduce a tiny tube into his heart through a blood vessel. Doctors said that the hole, a birth defect that affects 15 to 25 per cent of the population, was likely to have caused the blood clot that led to the stroke on December 18.

He will continue to receive two daily injections of a blood-thinning drug until the operation, which will reduce the likelihood of another blood clot forming.

Mr Sharon leads his new Kadima party into a general election on March 28 after splitting with Likud.

Doctors took the unusual step of disclosing medical records on Mr Sharon to dispel doubts about his health. The former general, who is 5ft 7in (1.7m), lost 6.6lb (3kg) in a week after being told to shed about 99lb (45kg). He will also modify his diet away from the fatty meats that he enjoys.

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