Sen. Bernie Sanders (I-VT) underwent heart surgery Tuesday night after experiencing pain in his chest. He is cancelling his campaign events “until further notice.”

According to his Senior Adviser Jeff Weaver, Sanders had a blockage in one artery and two stents were surgically inserted.

“Sen. Sanders is conversing and in good spirits,” Weaver said in a statement. “He will be resting up over the next few days.”

Per a doctor’s note he released during the 2016 campaign, Sanders has no history of heart disease.