Angioplasty and Stenting

Coronary Angioplasty and Stenting

Coronary angioplasty was developed in the 1970s and the first balloon angioplasty was undertaken in 1977.

The principal behind this procedure was that not only could the coronary arteries be imaged, as described in the section describing Cardiac Catheterisation (in Angina), but also, following the discovery of a tight narrowing in the artery, the procedure could be extended to try to remove or improve the narrowing in the artery.

This is achieved by passing a long thin wire down a guiding cardiac catheter whilst the tip of the catheter is placed in the coronary artery. The wire is then pushed further down the artery and through the narrowed segment. All of this is done under the x-ray machine so that precise positioning of the catheters and the wires can be achieved. A balloon catheter is then advanced over the wire such that a portion of the catheter which has a very low profile inflatable section (balloon) lies within the narrowed section of the coronary artery. Once this is in the correct position the balloon is inflated by applying pressure from outside of the body up the lumen (inside) of the catheter such that the balloon is blown up within the narrowed section of the coronary artery stretching the artery outwards and flattening the plaque that was causing the obstruction back against the insides of the artery wall.

The equipment room where coronary angiograms are carried out

The artery is checked after the procedure to see whether or not it has been successful and what degree of relief of obstruction has been achieved by introducing dye down the arteries in the same way as is carried out in a standard cardiac catheterisation. If necessary, successively larger balloons under greater pressure can be used to try and achieve a satisfactory end result.

In the next 10 15 years balloon angioplasty had such a significant impact on the treatment of coronary artery disease that the rates of coronary artery bypass grafts started to fall as more patients could be treated by this less invasive method of establishing better blood flow down their diseased arteries.

A significant problem remained, however, in that following the angioplasty procedure in some patients the narrowing (stenosis) recurred and often if it did so this happened fairly soon after the procedure itself. This phenomenon is known as recoil where the stretched walls of the arteries return back towards the position that they were before the balloon was deployed.

In 1993 a sophistication to the balloon angioplasty technique was added in an attempt to try and overcome the phenomena of recoil and re-stenosis and this was the introduction of the stent. Essentially a stent is a tube made of a metal mesh which has been compressed and fitted over the end of the angioplasty tube and once the angioplasty has been successfully completed, this stent is pushed off the end of the catheter such that it expands pressing up against the wall of the artery to, in effect, act as internal scaffolding to try to prevent the arterial walls squeezing back inwards again. If necessary even after deploying the stent, balloons can be inflated within the stent lumen to help to squeeze the artery out, further increasing the size of the arterial lumen and therefore the flow of blood down it.

Initial stents were made of bare metal and these quickly become covered by the cells that normally populate the inner wall of the artery called the endothelial cells. This occurs within the first 4 6 weeks. This is a natural process and doesnt necessarily lead to problems but in some cases the reaction of the artery to the stent can cause an over-proliferation of the cells leading to a phenomenon called in-stent stenosis.

To try to overcome this issue a decade later in 2003, drug eluting stents were introduced with the potential to reduce recoil and re-stenosis rates. Here instead of the stents being bare metal they have a coating which contains medication. These drugs that are coated on the stent are released locally and prevent the endothelial cells dividing and delay the re-epithelialisation of the inside of the artery which prevents the stent from becoming covered for up to 6 12 months.

A problem with both bare metal and drug eluting stents is the potential for clots to form in the artery as the clotting mechanism of the blood is potentially stimulated by the foreign metal material within the blood stream. The clotting potential is highest in the first 4 6 week after a stent has been deployed and with bare metal stents usually then gets significantly less as the endothelial cells cover the stent. With drug eluting stents which remain un-epithelialised however, this potential may exist for up to 12 months. To try to prevent clots forming it is usual to prescribe anti-platelet medication, usually Aspirin and Clopidogrel, and for bare metal stents this is usually continued as dual anti-platelet therapy for 3 6 months and for drug eluting stents for a year. To continue to help to protect against any progression of the coronary disease itself one of these medications, usually the Aspirin, will be continued lifelong.

Other innovations that have more recently come along in parallel with angioplasty and stenting are the use of instruments on the end of long thin catheters to reduce the material blocking the artery by methods of cutting it away. The rotablator and other instruments for atherectomy are sometimes used to do this and can be useful where the blockages are particularly bulky or have become hardened and difficult to expand by the use of a balloon technique alone.

A further development is the use of a miniature ultrasound probe at the end of a catheter that can be passed down a coronary artery so that the degree of narrowing can be accurately assessed if there is any doubt as to whether or not an angioplasty may be of value to the patient. This is called intra-vascular ultrasound or IVUS.

Another method of determining the degree of narrowing and the effect that it will have on a patient before deciding whether or not to undertake angioplasty is the use of a pressure wire where a catheter passed through the narrow portion of the artery can measure the pressure on either side of the narrowing giving a measurement of the pressure drop across the stenosis which helps to determine whether or not an angioplasty procedure should be carried out.

Angioplasties can be carried out to single vessels or multiple vessels and whilst they are most often carried out in the setting of a patient with ongoing angina to relieve symptoms they are increasingly being used in the very early stages of certain heart attacks (STEMIS) to reopen the artery which has been blocked by the formation of a clot in the narrowing precipitating the heart attack. Heart attack/Myocardial infarction Research has shown that carried out very early after the onset of the heart attack, this form of treatment can prove superior to the usual treatment of giving clot busting drugs (thrombolysis). This is called primary percutaneous coronary intervention or PPCI.


Patients who have had planned angioplasty can resume driving after one week if they are Group 1 licence holders (cars and motorcycles). If they are vocational licence holders (Group 2: PSV and HGV) they are disqualified for at least six weeks and until they can fulfil the requirements of a DVLA exercise test. DVLA

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