The 78-year-old experienced chest discomfort during an event on Tuesday and sought medical evaluation, according to a campaign statement.
It said two stents were inserted and Mr Sanders “is conversing and in good spirits”.
His campaign manager, Faiz Shakir, was on a telephone call with supporters on Tuesday night but did not mention any health concerns about the candidate. Mr Shakir said the “state of the campaign is strong” and played up Mr Sanders’ strong fundraising total for the third quarter.
Mr Sanders recently cancelled some appearances in South Carolina because he had lost his voice. The campaign said at the time he felt fine.
His aides have tried to project him as a candidate with energy levels that surpass his 2016 presidential campaign.
He is one of three candidates over 70 in the Democratic primary, which has spurred debate over whether the party should rally behind a new generation of political leaders.
His health scare is certain to revive that discussion in the weeks before the next presidential debate this month.
A letter released by his physician in 2016 cited a history of mildly elevated cholesterol but no heart disease.