John Fetterman, the Democratic Senate nominee from Pennsylvania, had a stroke in May.

The lieutenant governor of Pennsylvania secured his party's nomination just a few days later, setting up one of the most consequential Senate contests of the fall. There are urgent medical questions.

The campaign said on Sunday that he was discharged from the hospital, but did not say when he would return to campaigning.

Mr. Fetterman said in a statement that he was going to take time to rest and get to 100 percent so he could flip this seat blue.

The state of Mr. Fetterman's health is of interest to the public. Despite repeated requests, his campaign did not make him or his doctors available to discuss his medical treatment.

Some of the campaign's public statements don't offer enough explanation for Mr. Fetterman's diagnosis or treatment.

He said in a statement that the stroke was caused by a blood clot. He said the clot was the result of a condition in which the upper chambers of the heart beat chaotically and are out of sync with the lower chambers of the heart. The campaign said the clot was successfully removed by the doctors at the Lancaster General Hospital.

On the day of the primary election, Mr. Fetterman had a device implanted in his heart that will help protect his heart and address the underlying cause of his stroke, according to a statement from his press office.

Medical specialists asked about Mr. Fetterman's treatment. If he has a condition that puts him at risk of sudden death, like cardiomyopathy, it would make sense. The blood clot may have been caused by a heart condition. Doctors say the campaign could be correct aboutfibs.

Mr. Fetterman experienced more than a small stroke, which may have been avoided with prompt treatment, according to the method likely used to remove the clot.

Mr. Fetterman said that he was in the hospital for over a week.

Gisele Fetterman told the story of her husband's stroke in an interview on May 20.

She said that they had had breakfast after campaigning.

She said that the left side of his mouth drooped for a second when they got into the car.

Ms. Fetterman said she had a hunch that the trooper was having a stroke. What are you talking about? I feel fine.

ImageGisele Barreto Fetterman, Mr. Fetterman’s wife, spoke at a watch party in Pittsburgh on May 17.
Gisele Barreto Fetterman, Mr. Fetterman’s wife, spoke at a watch party in Pittsburgh on May 17.Credit...Maddie McGarvey for The New York Times
Gisele Barreto Fetterman, Mr. Fetterman’s wife, spoke at a watch party in Pittsburgh on May 17.

The trooper drove Mr. Fetterman to the hospital. According to Ms. Fetterman, he had a procedure in which a small plastic tube was slid through his groin and into his brain to remove a blood clot.

His campaign did not report that Mr. Fetterman had a stroke until two days later. Ms. Fetterman said that less than 48 hours is impressive when dealing with sensitive medical issues.

After the question was asked, a senior adviser in Mr. Fetterman's campaign abruptly ended the call with Ms. Fetterman.

Some aspects of the story were hard to reconcile with their knowledge of stroke treatment.

Dr. Lee Schwamm, a stroke specialist at Massachusetts General Hospital and professor of neurology at Harvard Medical School, said doctors only do a thrombectomy when a large arteries in the brain is blocked.

He said that you wouldn't do it for someone with just a little bit of facial droop. Dr. Schwamm wondered if the doctors who examined Mr. Fetterman had noticed other symptoms, like a loss of vision on his left side or lack of awareness of his left side.

The strokes tend to be very severe, and he is fortunate that he went to a hospital that could treat it.

The spokesman for Mr. Fetterman told The Associated Press last week that Gisele noticed that John was not himself.

What caused the stroke?

Ms. Fetterman said that her husband had taken anti-coagulants, a standard method of reducing the stroke risk in people with a high risk of stroke, because he knew he had a high risk of stroke.

If he only had a problem with the heart, the treatment with a pacemaker and defibrillator would be difficult.

"This doesn't make sense, it's not entirely logical," said Dr. Brahmajee Nallamothu, an interventional cardiologist at the University of Michigan.

Dr. Elaine Wan, an associate professor of medicine in cardiology and cardiac electrophysiology at Columbia University Medical Center, said that defibrilators are used to prevent sudden death. They are usually implanted in people with weakened heart muscle or people with a genetic susceptibility for sudden cardiac death.

Dr. Wan said that they wouldn't use it for atrial fibrillation.

Dr. Rajat Deo, an associate professor of medicine at the University of Pennsylvania's Perelman School of Medicine, agreed with Dr. Wan's suspicion that Mr. Fetterman had a heart attack.

Mr. Fetterman has at least two issues, one of which is afib.

The second issue is that he has an underlying cardiac condition that increases his risk for sudden cardiac death.

The other condition could be related to the afib. Patients with a weakened heart muscle are more likely to have a heart problem.

Mr. Fetterman may have nothing to do with his weakened heart. It is not possible to know without more information from his doctors.

If Mr. Fetterman is protected with a defibrillated heart from sudden cardiac death, he should do well while he continues his campaign.

Dick Cheney, the former Vice President, had a defibrillator implanted in 2001. He was re-elected in 2004, after two terms in the White House.

The Republican race in Pennsylvania is too close to call and may go to a recount, so there is time before general election campaigning begins.

Dr. Wan was less positive about Mr. Fetterman.

She said that he was at risk for sudden cardiac death.