Angioplasty. Computer illustration showing coronary angioplasty. A stent (wire mesh) is being positioned in an artery narrowed by atherosclerosis. The wire-like catheter has been inserted into the artery and moved to the site of the constriction. Here, a balloon will be inflated, in order to expand the stent which will hold the artery open after the balloon has been deflated and the catheter removed. This procedure is known as balloon angioplasty. The most common cause of arterial narrowing is atherosclerosis, the deposition of fatty plaques of atheroma (yellow) on the inner wall of an artery.