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A coronary stent is a tube-shaped device placed in the coronary arteries that supply blood to the heart, to keep the arteries open in the treatment of coronary heart disease. It is used in a procedure called percutaneous coronary intervention (PCI). Stents reduce chest pain and have been shown to improve survivability in the event of an acute myocardial infarction. Similar stents and procedures are used in non-coronary vessels e.g. in the legs in peripheral artery disease. ==Uses== Treating a blocked ("stenosed") coronary artery with a stent follows the same steps as other angioplasty procedures with a few important differences. The interventional cardiologist uses angiography to assess the location and estimate the size of the blockage ("lesion") by injecting a contrast medium through the guide catheter and viewing the flow of blood through the downstream coronary arteries. Intravascular ultrasound (IVUS) may be used to assess the lesion's thickness and hardness ("calcification"). The cardiologist uses this information to decide whether to treat the lesion with a stent, and if so, what kind and size. Drug eluting stents are most often sold as a unit, with the stent in its collapsed form attached onto the outside of a balloon catheter. Outside the US, physicians may perform "direct stenting" where the stent is threaded through the lesion and expanded. Common practice in the US is to predilate the blockage before delivering the stent. Predilation is accomplished by threading the lesion with an ordinary balloon catheter and expanding it to the vessel's original diameter. The physician withdraws this catheter and threads the stent on its balloon catheter through the lesion. The physician expands the balloon which deforms the metal stent to its expanded size. The cardiologist may "customize" the fit of the stent to match the blood vessel's shape, using IVUS to guide the work.〔(Intravascular Ultrasound - Angioplasty.Org )〕 It is critically important that the framework of the stent be in direct contact with the walls of the vessel to minimize potential complications such as blood clot formation. Very long lesions may require more than one stent—this result of this treatment is sometimes referred to as a "full metal jacket". The procedure itself is performed in a catheterization clinic ("cath lab"). Barring complications, patients undergoing catheterizations are kept at least overnight for observation.〔(Angioplasty 101 ) Angioplasty.Org〕 Dealing with lesions near branches in the coronary arteries presents additional challenges and requires additional techniques.〔http://indianheartjournal.com/ihj06/mar_apr_06/108-119.html〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Coronary stent」の詳細全文を読む スポンサード リンク
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