A stent is a small mesh tube that is placed in a narrowed artery to hold it open. This helps improve blood flow to your heart. The stent also helps keep the artery from re-narrowing (restenosis). Most stents are coated and slowly release medicine over time. This reduces the amount of scar tissue that forms in the artery, helping prevent restenosis. A heart specialist called an interventional cardiologist does coronary angioplasty and stenting.