Coronary angioplasty, also called PTCA, PCI or the balloon procedure, is the method used to deal with tight narrowings in the coronary arteries that are affecting the blood supply to the heart. Developed more than a quarter of a century ago, since when there have been many remarkable technological advances, the technique is frequently used to treat angina. There are some similarities to cardiac catheterisation in that it is also performed in the catheter laboratory (cath lab) with very similar equipment but there are also fundamental differences.

Whereas cardiac catheterisation is an investigative tool, angioplasty is a treatment. Again, a fine flexible tube (2 – 3 mm in diameter) is passed up the artery in the leg or arm under local anaesthetic to the coronary artery using X-ray guidance. An extremely fine wire is passed along the tube and into the narrowed coronary artery. A very small deflated balloon is then threaded over the wire and up into the coronary artery to the site of the narrowing. There it is inflated, pushing the atheroma (furring up) into the vessel wall to remove the obstruction to blood flow. This simple concept is surprisingly effective. However, if only a balloon is used approximately one third of the narrowings recur, typically within the first four months of the procedure. This is called restenosis. To minimise the risk of restenosis, coronary stents have been developed. A stent is a precision-made tube or mesh, constructed from stainless steel or similar alloy. It is mounted on the deflated angioplasty balloon such that when the balloon is inflated the stent expands to form a mesh-like scaffold to keep the artery open. It is a permanent device which remains in the artery when the deflated balloon is removed. Following stent insertion the likelihood of the narrowing recurring to such an extent that chest pains recur is small.

In the last few years research has focussed on reducing the restenosis rates even further. Although restenosis rates are much lower after stenting than after simple balloon angioplasty, there is still a possibility of restenosis. Trials have investigated so called "drug-eluting stents", stents which are impregnated with minute amounts of a drug that inhibits the process of restenosis. The results are impressive, with restenosis rates in single figures such that drug-eluting stents are now used preferentially over "bare metal stents" in many cases, especially in smaller arteries and longer narrowings, where restenosis rates with bare metal stents are typically higher than usual.

Patients are given special medicines to keep the blood thin during and following angioplasty/stenting, to minimise the risk of the artery closing down at the site of the narrowing. Generally speaking most patients stay in hospital overnight following the procedure, during which time they are carefully monitored.