Coronary angiography, also called cardiac catheterisation, is a specialised X-ray test to find out highly detailed information about the coronary arteries. It is mainly used to work out the extent and severity of furring up in the coronary arteries, which can be felt as symptoms like chest pain or lead to a heart attack. A coronary angiogram is considered to be the “gold standard” for establishing the best type of treatment for the patient, i.e. medication, angioplasty or bypass surgery.
If you need a coronary angiogram you will be admitted to hospital as a day case and asked not to eat or drink for 6 hours prior to the procedure. You will be offered IV sedation prior to the procedure You will lie on a table in the cardiac catheter lab, which looks similar to an operating theatre, and an X-ray machine is mounted above and moves around to take the pictures. Dr Hyde will inject some local anaesthetic into the skin above the blood vessel in the wrist or groin to numb the area. A short tube (sheath) is then inserted through a 3mm cut in the skin into the blood vessel, and through this short tube different shaped long thin tubes (catheters) are passed to the heart and to the coronary arteries.
X-rays are used to monitor the progress of the catheter, which is positioned at the origin of the coronary arteries. Once in position dye is injected through the catheter, the x ray machine will activate whilst the dye is passing through the vessel and detailed images are created which show whether or not there are any narrowings, the results are available on the day. Dr Hyde will take usually 8 or 9 images and the test takes around 10 minutes.
Coronary Angioplasty and Stenting
Angioplasty is a treatment used to deal with tight narrowings in the coronary arteries which affect the blood supply to the heart. Coronary angioplasty was first undertaken in the 1970s, and since that time many remarkable technological advances have greatly increased the types of heart conditions that can be successfully treated with this technique. Initially used to treat angina caused by a narrowing in one coronary artery, angioplasty is now a highly effective treatment for patients with a number of narrowings, and not only in the stable elective situation but also in the emergency treatment of a heart attack, so called primary angioplasty. Angioplasty is almost always now followed by stent implantation. A stent is a balloon mounted expandable metal cylinder that is deployed inside the artery and holds it open like a scaffold whilst holding back or trapping any plaque that was causing a narrowing.
Angioplasty is similar to a coronary angiogram in that it is also performed in the catheter laboratory with very similar equipment, but there are also fundamental differences, that is angiography is used to investigate the heart while angioplasty is a treatment.
During the procedure itself, under local anaesthetic a fine flexible tube 2 to 3 mm in diameter is passed up the artery from the groin or wrist to the coronary artery using X-ray guidance. An extremely fine wire is passed along this tube, into and beyond the narrowing in the coronary artery. A very small deflated balloon is then passed over the wire and up to the site of the narrowing. There it is inflated, pushing the atheroma (furring up) into the vessel wall to relieve the obstruction to blood flow. Balloon inflation is then followed by stent deployment. The procedure can take around 15 minutes in simple cases.
After stent implantation the coronary artery forms a thin layer of cells over the stent struts. Until this is complete the metal struts have the potential to provoke clot or thrombus formation within the stent, which carries the risk of a heart attack. This is minimised by taking a combination of two blood thinners, aspirin and either clopidogrel or ticagrelor, for a set period of time, following which most patients can reduce to aspirin alone. Dual antiplatelet therapy, with aspirin and clopidogrel or ticagrelor, is given for a time period which is determined by the clinical scenario and the type of stent implanted; bare metal stents may only need this combination therapy for one month if implanted in an elective situation, while drug-eluting stents require the combination for one year and sometimes more, and most patients treated as emergency cases are given this treatment for up to one year. There are also occasions where a patient may be advised to remain on both drugs indefinitely.
More recently bioabsorbable stents have been developed, which gradually dissolve over time, leaving behind only the healed natural artery. They have several potential advantages over metal stents; in particular they are less likely to cause clots and so the requirement for dual antiplatelet therapy will be reduced. This is currently an area provoking considerable interest and research.
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