Democratic presidential candidate and Vermont Sen. Bernie Sanders was taken to a hospital Tuesday night.

A statement from his senior adviser, Jeff Weaver, said that at a campaign event in Las Vegas, Sanders, 78, “experienced some chest discomfort. Following medical evaluation and testing he was found to have a blockage in one artery and two stents were successfully inserted.”

Weaver said Sanders was “conversing and in good spirits,” and is “canceling events and appearances until further notice.”