Retiring Congressman John Dingell will undergo a "minimally invasive" heart procedure at a Detroit hospital Thursday.
“He recently developed atrial fibrillation, and the procedure will seek to find the source of the abnormal heart rhythm and correct it," said spokesman Christopher Schuler.
Dingell, 87, will stay overnight at Henry Ford Hospital in Detroit and is expected to be released on Friday.
The Michigan Democrat was elected to Congress in 1955, at the age of 29, and has served as the representative from the 12th District ever since. He became the longest-serving member of Congress in U.S. history on June 7, 2013.
He announced last month he would retire at the end of the term. His wife, Debbie Dingell, is running to replace him.