Plaque accumulation in the walls of the coronary arteries, which provide blood to the heart and other parts of the body, is the cause of coronary artery disease. Deposits of cholesterol and other materials in the artery make up plaque. Over time, plaque accumulation narrows the inside of the arteries, obstructing blood flow either completely or partially. The purpose of percutaneous coronary intervention, (PCI), is to enhance blood supply to the ischemic region and reduce coronary artery constriction or blockage. This is typically accomplished by a variety of techniques, one being inflating the constricted area or inserting a stent to ensure the artery remains open.