Treatment of a narrowed subclavian artery. Coloured angiograms showing treatment of a narrowed subclavian artery below a 58-year-old patient's left clavicle. The left image shows severe stenosis (narrowing, arrowed) in the artery, usually caused by atheroma (fatty deposits on the inner wall). The centre image shows a stent (wire mesh tube) in this narrowed region. The stent has been guided into place by a balloon catheter (pale line running from right edge to centre bottom), which has been inflated to expand the stent. The artery has not been injected with iodine so it is not visible here. In the right image, the catheter has been deflated but the stent remains expanded to hold open the artery for normal blood flow.