The main indications of coronary angiography with or without stent implantation are stable or unstable angina, myocardial ischemia, myocardial infarction. Elective indication is for patients with angina who remain symptomatic despite optimal medical treatment.
Percutaneous transluminal coronary angioplasty is done by puncturing a peripheral artery (femoral, radial) through which is advanced a catheter guide to the coronary arteries. Under fluoroscopic guidance a catheter with a balloon is positioned within the stenotic area (clogged), the balloon will be inflated and the plaque will be broken and the vessel (coronary artery) will be dilated. This procedure can be used for 2-3 vessels.
The most common complication that occurs after percutaneous transluminal coronary angioplasty is restenosis which will require reintervention or surgery (CABG). Stenosis rate is high in the first half of the year, but can be prevented by stenting and the use of anticoagulant drugs during intervention.
Stents are used to treat short lesions that were not previously treated with angioplasty. To reduce the risk of restenosis some stent limit the local intimal proliferation of the vessel by releasing substances like sirolimus and paclitaxel.
Risks of mounting a stent: thrombosis, restenosis, bleeding due to anticoagulation therapy, collateral branches stenosis, embolism. Intrastent thrombosis is prevented by administration of anticoagulant therapy like clopidogrel (Plavix) and glycoprotein inhibitors IIbIIIa. These treatments are required for 9-12 months post-intervention. Coronary spasm is prevented by administration of calcium channel blockers and nitrates.
Absolute contraindications: absence of cardiovascular surgery service, significant obstruction of the left coronary artery without presence of bypass graft.
Relative contraindications: coagulopathy, hypercoagulable states, diffuse vascular disease, damage of a vessel that offers the full nutrition of myocardium, total occlusion of the coronary artery.
There is also the risk of nephropathy secondary to the use of contrast substance. The risk is reduced by adequate hydration of the patient prior to surgery or use of a nonionic contrast agent.