Kennedy, 70, had a stent inserted Saturday at Washington Hospital Center. The device is a tiny mesh scaffold used to keep arteries open.
The court called the procedure a revision to the stent doctors put in Kennedy in November. The justice did not make his health news public at the time.
A common problem with stents is that tissue grows back through them and recloses the blood vessel.
Doctors found no evidence of heart damage, the court said in a brief statement. He was released from the hospital Sunday and has since returned to work.
The court's new term begins Oct. 2.