Israeli Prime Minister Ariel Sharon is to undergo an operation on Thursday to close a small hole which doctors found in his heart after his recent stroke.
Mr Sharon has resumed his full workload after his stroke
Mr Sharon will stay in hospital overnight after the procedure.
The hole in his heart is thought to have contributed to the minor stroke Mr Sharon suffered on 18 December, doctors said last week.
Mr Sharon, 77, plans to run for a third term in office in March, under his newly-formed centrist party, Kadima.
Revealing the heart problem last week, one of Mr Sharon's doctors, Chaim Lotem, said the hole was a common minor birth defect.
He said it would be sealed with an "umbrella-like" device inserted by running a small tube through a blood vessel.
Doctors have said that Mr Sharon suffered no lasting damage from the stroke, and that his blood pressure and cholesterol levels are normal.
Mr Sharon returned to work after leaving hospital last month and has resumed his full workload - but correspondents say questions about his health will dog the election campaign.
Releasing the prime minister's medical records last week, doctors said the stroke was "very minor". Although Mr Sharon's powers of speech were affected for several hours, the records say, the stroke had no impact "on his memory and other faculties".
Mr Sharon quit the ruling Likud party in November to set up his new party.
His rival Binyamin Netanyahu subsequently won the Likud party leadership.
Mr Sharon has been prime minister since 2001, and polls suggest his new party is in the lead ahead of the election.