Sen. Tom Coburn (R-Okla.) is undergoing tests at a Washington-area hospital Friday for an irregular heartbeat that he began experiencing Thursday night, according to his aides.

Coburn, 60, has not been admitted to the hospital, according to spokesman John Hart, and is expected to return to the Senate for its Saturday session.

“He is at the hospital having tests for common arrhythmia. He has not been admitted to the hospital and expects to return tomorrow,” Hart said.

Hart said Coburn does not have a history of heart problems. The Senator, who is a doctor, has survived colon cancer and melanoma.