Mr. Sharon, 77, suffered the stroke on Dec. 18 and was hospitalized for two days. Doctors said there was no permanent damage, and Mr. Sharon has returned to work, leading the regular weekly cabinet meeting on Sunday.
The prime minister's health problem has emerged as he seeks a third term in national elections on March 28. Opinion polls indicate that his new centrist party, Kadima, remains heavily favored, despite his ailments.
Dr. Chaim Lotan, the chief of cardiology at Hadassah University Medical Center here, told reporters that tests conducted while Mr. Sharon was hospitalized had found the hole in his heart, less than an eighth of an inch wide.
Dr. Lotan said doctors planned to use a catheter to insert a device to seal the hole, which is located in the atrial septum, the wall between the left and right upper chambers of the heart. Such holes are a relatively common birth defect, and many people live long, healthy lives without ever knowing they have such a condition, doctors say.
The procedure to repair the hole will place a tiny device shaped like an umbrella over the hole. It takes about 30 minutes and is considered routine, doctors added.
Normally, blood flowing from veins in the body passes through the right side of the heart en route to the lungs, where it picks up oxygen and returns through other blood vessels to be pumped out of the left side of the heart to the aorta and the body. A hole in the septum can allow blood to flow from the right atrium to the left atrium, bypassing the lungs.
If a clot is present in the blood flowing on the right side, the clot would normally go to the lungs. But if the clot passes through the hole into the left side of the heart, it is then carried by the flow of blood through the aorta into the arteries that go to the body and can lodge in the brain, causing a stroke.
Because it can be difficult to prove that a stroke resulted directly from a hole in the atrial septum, doctors strive to rule out other causes before closing the hole.
Dr. Basil Lewis, a prominent Israeli cardiologist who is not involved in treating Mr. Sharon, described the procedure Mr. Sharon will undergo as straightforward.
"I would expect him to be back at work in a day or two," said Dr. Lewis, the chief of cardiology at the Lady Davis Carmel Medical Center in Haifa.
Mr. Sharon's doctors spoke to reporters after calls for additional details on his medical condition. The doctors have urged Mr. Sharon to diet. He is 5 feet 7 and weighed 260 pounds at the time of the stroke. He has lost six pounds in the last week, the doctors said.
Parts of a draft of Mr. Sharon's Kadima Party platform were published Monday in the newspaper Maariv, which had obtained a copy. The draft says the party will pursue peace efforts with the Palestinians, acknowledging that such a move would ultimately require Israel to relinquish more land and result in the establishment of a Palestinian state.
Kadima will work to define Israel's permanent borders if it wins the election, it says. "The basic tenet of the peace process is two national states," the platform says. Kadima's goal will be to "lay the foundations to shape the permanent borders of the state of Israel."
Mr. Sharon has made similar remarks recently, though he has not said where he wants to draw the borders. The Palestinians are sure to reject boundaries that are not negotiated between the two sides.
Israel's separation barrier in the West Bank is widely seen as the basis for any border that Mr. Sharon might seek. About 10 percent of the West Bank is on the Israeli side of the barrier, including the major Jewish settlement blocs.
The Palestinians are seeking all of the West Bank, and East Jerusalem, as part of a future state, along with the Gaza Strip.
On Monday, the Housing Ministry announced plans for 228 new housing units in the large Gush Etzion settlement bloc in the West Bank a few miles south of Jerusalem. The stalled Middle East peace plan calls for a freeze on building settlements, but Israel continues to build houses and apartments in existing settlements.
A Palestinian court ruled Monday that the Fatah movement of the Palestinian leader, Mahmoud Abbas, can still submit a single list of candidates for parliamentary elections planned on Jan. 25.
Younger leaders in Fatah said they were breaking away from the movement and submitted their own list of candidates on Dec. 14, the final day of registration. The old guard and the young guard in Fatah now appear to have reconciled, but they needed the court's permission to place their candidates on a single list, since the registration deadline had passed.
But the Palestinian election still faces other unresolved issues.
Israeli officials say they have not made a final decision on whether Palestinians in East Jerusalem will be allowed to vote inside the city limits. Israel has permitted Palestinians there to vote in previous Palestinian elections, including the one that chose the president of the Palestinian Authority last January.
But Israel says it is opposed this time because of the participation of Hamas, an Islamist faction that calls for the destruction of Israel. Hamas did not field candidates in previous elections, but it is doing so this time and is expected to make a strong showing.
The Palestinian prime minister, Ahmed Qurei, on Monday reiterated a threat to call off the election if East Jerusalem residents are not allowed to vote there.
"Voting in Jerusalem is an essential condition for the holding of elections," Mr. Qurei said, speaking in the West Bank city of Ramallah.
