Coronary angiography is used to visualize the inside of coronary arteries. This procedure involves placing a catheter into a blood vessel to release dye into the bloodstream. Because of the dye, doctors can view blockages of arteries using an x-ray machine. If blockages are found, the doctor might perform percutaneous coronary intervention (PCI). PCI will open these blocked arteries, restoring proper blood flow. In this procedure, a catheter attached to a deflated balloon will be inserted into the blocked area. Inflating the balloon helps reduce or remove the blockage, thus restoring blood flow.