Stenosis of the coronary arteries is usually caused by deposition of atherosclerotic plaque. This reduces blood flow to the heart muscle and is usually progressive. Symptoms of coronary artery disease typically include angina (chest pain that is exacerbated by exertion). A critical reduction of the blood supply to the heart may result in myocardial infarction or death.
The symptoms from a stenosed artery may be treated medically. This includes modifying risk factors (for example, smoking, hyperlipidaemia, obesity, hyperglycaemia) and treatment with medicines (for example, beta blockers, nitrates, calcium-channel blockers, antiplatelet agents, statins).
If medical management fails or is inappropriate, the usual options are coronary artery bypass grafting, or percutaneous transluminal coronary angioplasty followed by stent insertion to maintain the patency of the coronary artery.
Bioresorbable stents are designed to be absorbed by the body over time. One aim is to reduce the risk of late complications such as thrombosis, which may happen after using metal stents. The other is to reduce the need for long-term antiplatelet medicines, with their risk of bleeding complications.
The procedure is done under local anaesthesia. A guidewire is passed into the target coronary artery, usually from the radial or femoral artery under fluoroscopic image guidance. A balloon angioplasty catheter passed over the guidewire is used to dilate the coronary artery stenosis. A bioresorbable stent mounted on a balloon catheter is passed over the guide wire into the relevant segment of the artery. Then, it is expanded by inflation of the balloon inside it. The balloon is then deflated and removed with the guide wire. The stent acts as a scaffold to hold the vessel open. Additional imaging, such as intravascular ultrasound and optical coherence tomography, is sometimes used to guide the procedure. This is to optimise positioning and deployment of the stent in the target coronary artery.
Bioresorbable stents are absorbed over time. Most bioresorbable stents are also drug-eluting, with a view to reducing the risk of restenosis. Antiplatelet medicines such as aspirin and clopidogrel are usually prescribed for at least 6 months after the procedure.