Placement of a stent in a coronary artery with plaque buildup. The coronary artery is located on the surface of the heart. Figure A shows the deflated balloon catheter and closed stent inserted into the narrowed coronary artery. In figure B, the balloon is inflated, expanding the stent and compressing the plaque to restore the size of the artery. Figure C shows normal blood flow restored in the stent-widened artery.