There isn't much information, but the longest serving Congressman has been hospitalized due to "discomfort."
Dingell, D-Mich., was fully conscious and admitted as a precautionary measure, his office said. Dingell had been working in his Capitol Hill office when he decided to seek medical treatment.
Spokesman Adam Benson said the congressman joked with staff on his cell phone on the way to the hospital.
Chicago Tribune
According to the Detroit News
Dingell was in the Capitol performing physical therapy exercises when he experienced shortness of breath and a physician advised him to go the hospital as a precaution.
He underwent surgery to replace his left knee on Oct. 24.
Dingell is 82, and was elected in 1955 and is the longest-serving member of the U.S. House.