Causes
Surgery to widen or unblock a blood vessel usually has a long lasting beneficial effect for the patient. However in some cases, the procedure itself can cause further narrowing of the vessel, or restenosis. Angioplasty also called Percutaneous transluminal coronary angioplasty (PTCA) is commonly used to treat blockages of the coronary arteries,or peripheral arteries such as the limbs. The balloon inserted into the narrowing ‘smashes’ the cholesterol plaques (atherosclerosis) against the artery walls, thus widening the size of the lumen and increasing blood flow. However the action does damage to the artery walls, and it responds by using physiological mechanisms to repair the damage. (See physiology below)
A stent is a mesh tube-like structure often used in conjunction with angioplasty to permanently hold open an artery, allowing for unrestricted blood flow, or to support a weakness in the artery wall called an aneurysm. The artery can react to the stent, perceive it as a foreign body and respond by mounting an immune system response (see physiology below) which leads to further narrowing near to or inside the stent.
Read more about this topic: Restenosis