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المستخلص
The constant activity of the beating heart means there is a high demand for oxygen consumption which is under normal resting conditions blood flows through the myocardium at a rate of 5 to 10 ml/min/100g, which amounts to about 4% of the cardiac output. Under
maximal load as during strenuous exercise, the heart in young adult increases its cardiac output fourfold to sevenfold. Coronary arteries exhibit some degree of autoregulation, which acts to maintain coronary blood flow within tightly controlled limits over a perfusion pressure range of (60 and 200 mmHg) independent of myocardial oxygen demand Myocardial ischemia occurs as a result of increased myocardial oxygen demand, reduced myocardial O2 supply or both. Acute occlusion of a coronary artery most frequently occurs in a person who already has underlying atherosclerotic coronary heart disease . Early reperfusion using percutaneous coronary interventions, such as angioplasty; stent placement; or thrombolytic therapy) is by far the most effective treatment A coronary stent is an artificial support device used in the coronary artery to keep the vessel open and maintain wide luminal patency. There are two major types of coronary artery stents: bare metal stents (BMS) and drug-eluting stents (DES) .Coronary artery stents are associated with many complications such as thorombosis, restenosis, side-branch occlusion, stent embolization, arterial perforation and coronary abscess.Antiplatelet therapy is mandatory for patients after coronary artery stenting as platelets play a major role in thrombus formation.Clopidogrel combined with aspirin is the commonly prescribed regime.The management of patients with a coronary stent presenting for both elective and emergency non-cardiac surgery is an increasing clinical problem. Management depends upon the type of surgery whether emergency or elective. For emergency surgery antiplatelet therapy should be continued whenever possible. If the bleeding risk is unacceptable and mandate stopping clopidogrel, it should be stopped for as minimum time as possible and restarted as soon as possible. Aspirin is continued throughout the perioperative period.The risk of discontinuing clopidogrel and aspirin preoperatively outweighs the benefit of reduced hemostasis, especially in patients with procedural complexities, which place them at higher risk for developing stent thrombosis.