Percutaneous coronary intervention (PCI) is a procedure used to restore blood flow through narrowed or blocked arteries in the heart. Blockages in the coronary arteries are the cause of angina (chest pain and similar symptoms) and ultimately can lead to myocardial infarction (heart attack). PCI involves the insertion of a balloon into the artery which is then inflated to push the buildup of materials against the wall of the artery. Typically, a metal mesh tube called a stent is mounted on the balloon and, once deployed, serves as a scaffolding to hold the artery open at the site of the intervention. The use of drug-eluting stents has reduced the recurrence rate of blockage after a stent to extremely low levels.