A stent is an expandable metal mesh tube used in the angioplasty procedure. The stent is placed at the site of the blockage to keep the artery open. Stents or balloons can also be used as the initial opening device of the artery. The stent remains in the artery and pushes against the walls to keep it open. In 10 to 15 percent of stent procedures need to be repeated to restore the opening.