Percutaneous coronary intervention is a nonsurgical procedure that opens blocked or narrowed coronary arteries. A thin, flexible tube (catheter) with a balloon or other device on the end is threaded through a blood vessel, usually in the groin (upper thigh), to the narrowed or blocked coronary artery. Once in place, the balloon located at the tip of the catheter is inflated to compress the plaque and related clot against the wall of the artery. This restores blood flow through the artery. During the procedure, the doctor may put a small mesh tube called a stent in the artery. The stent helps to keep the blood vessel open to prevent blockages in the artery in the months or years after the procedure.