Coronary angioplasty: Investigations and procedures

Investigations and procedures

Coronary angioplasty

Coronary angioplasty is a technique used to dilate stenosed coronary arteries in patients with ischaemic heart disease. The indications for use of angioplasty have changed over the years with the technique now used for many stenoses previously thought to be treatable only by bypass grafting. Current practice is for left main stem disease or triple vessel disease to be treated by bypass grafting for prognostic reasons with almost all other lesions being considered for angioplasty for symptom control. In addition, patients with concomitant conditions precluding bypass surgery, e.g. lung disease, may be considered for angioplasty even for left main stem or advanced multivessel disease.

Early angiography and angioplasty is now being increasingly used immediately following a myocardial infarction, in order to reduce the risk of further infarction. This is especially where the acute event is a limited or non-ST elevation myocardial infarction.

PTCA (percutaneous transluminal coronary angioplasty) is performed under local anaesthetic. A small balloon is passed up the aorta via peripheral arterial access under radiographic guidance. Once within the affected coronary artery, the balloon is inflated to dilate the stenosis, compressing the atheromatous plaque and stretching the layers of the vessel wall to the sides. A stent is often used to reduce recurrence. Some stenoses cannot be dilated due to calcification of the vessel, small vessel or the position or length of stenosis. During the procedure there is a risk of thrombosis, so patients are given intravenous heparin and aspirin. If stents are used, another antiplatelet agent (clopidogrel) is also used to prevent instent thrombosis in the first few days/weeks and the patient remains on lifelong aspirin.

Complications

The main immediate complication of balloon angioplasty is intimal/medial dissection leading to abrupt vessel occlusion. This, and the problem of late restenosis, has been largely resolved with the routine implantation of a stent. There is a risk of complications, including emergency coronary artery bypass surgery, myocardial infarction and stroke (due to thrombosis and plaque, or haemorrhage) but these tend to be lower than for coronary artery bypass surgery. More commonly, local haematoma at the site of arterial puncture may occur. Overall mortality is approximately 0.5%.

Prognosis

Depending on the anatomy of the lesion, significant restenosis occurs between 30 and 60% after balloon angioplasty without stenting. Stent implants generally reduce this to approximately 15–20% and this has been further reduced with drugeluting stents. These slowly release a drug (e.g. sirolimus) over 2–4 weeks to modify the healing response.