|
Unstable angina (UA) is a type of angina pectoris that is irregular. It is also classified as a type of acute coronary syndrome. It can be difficult to distinguish unstable angina from non–Q-wave myocardial infarction. Unstable angina (UA) and non-ST elevation (non-Q wave) myocardial infarction (NSTEMI) differ primarily in whether the ischemia is severe enough to cause sufficient myocardial damage to release detectable quantities of a marker of myocardial injury. Unstable angina is considered to be present in patients with ischemic symptoms suggestive of an ACS and no elevation in troponin, with or without ECG changes indicative of ischemia (e.g., ST segment depression or transient elevation or new T wave inversion). Since an elevation in troponin may not be detectable for up to 12 hours after presentation, UA and NSTEMI are frequently indistinguishable at initial evaluation. ==Definition== Unstable angina is angina pectoris caused by disruption of an atherosclerotic plaque with partial thrombosis and possibly embolization or vasospasm.〔Robbins. Pathologic basis of disease 7th edition.2005.〕〔http://circ.ahajournals.org/cgi/content/full/98/21/2219〕 It is characterized by at least one of the following: # Occurs at rest or minimal exertion and usually lasts more than 20 minutes (if nitroglycerin is not administered) # Being severe (at least Canadian Cardiovascular Society Classification 3) and of new onset (i.e. within 1 month) # Occurs with a crescendo pattern (brought on by less activity, more severe, more prolonged or increased frequency than previously).〔Braunwald E, Antman EM, Beasley JW, et al: ACC/AHA guideline update for the management of patients with unstable angina and non-ST segment elevation myocardial infarction-2002: Summary Article: A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on the Management of Patients with Unstable Angina). Circulation 2002; 106:1893-1900.〕〔Libby: Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine〕 Fifty percent of people with unstable angina will have evidence of myocardial necrosis based on elevated cardiac serum markers such as creatine kinase isoenzyme (CK)-MB and troponin T or I, and thus have a diagnosis of non-ST elevation myocardial infarction.〔〔Markenvard J et al. The predictive value of CKMB mass concentration in unstable angina pectoris: preliminary report. Journal of Internal Medicine. 1992 Apr;231(4):433-6.〕 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「Unstable angina」の詳細全文を読む スポンサード リンク
|