Coronary stent. Coloured scanning electron micrograph (SEM) of a stent (wire mesh tube, blue), which is used to treat stenosis (narrowing) of the coronary arteries. The procedure used to insert the stent into the artery is referred to as an angioplasty, where a balloon catheter guides the stent inside the artery. A region of the catheter is then inflated in order to expand the stent. When the catheter is deflated and removed, the stent retains its expanded shape, keeping the artery open to ensure normal blood flow. Magnification: x60 when printed at 10cm wide.