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Unstable Angina
Alternate Names : Accelerating Angina, Angina - Unstable, New-Onset Angina, Progressive Angina
Definition
Unstable angina describes a syndrome that is intermediate between stable angina and myocardial infarction: an accelerating or "crescendo" pattern of chest pain that lasts longer than stable angina, occurs with less exertion or at rest, or is less responsive to medication.
Unstable angina and myocardial infarction are considered acute coronary syndromes, while stable angina is a chronic condition.
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Overview, Causes, & Risk Factors
Unstable angina occurs in approximately 6 out of every 10,000 people. Coronary artery disease due to atherosclerosis is by far the most common cause of unstable angina. A coronary artery spasm is a rare cause of angina.
Initially, narrowing (in the form of atheroschlerotic plaques) of the coronary arteries may be severe enough to cause stable angina with exertion or stress. This narrowing, however, sometimes causes no symptoms at all.
For reasons that are not well understood, the plaques reach a point at which they rupture. Under these circumstances, a plug formed by platelets and blood clots may form, causing an already narrowed blood vessel to become highly susceptible to becoming completely blocked. This unstable situation may progress to complete occlusion of the vessel, with infarction of the heart muscle (heart attack).
Once this type of lesion exists in a coronary artery, and whether the event leads to a heart attack or not, the chest pain produced by the extreme narrowing of the coronary artery may become unstable. Unlike stable angina, in which chest pain can be induced by exercise or stress, chest pain in unstable angina may occur at rest and without any precipitating factors. Pain may increase in severity, frequency, or duration at low levels of activity or for no identifiable reason. This type of angina may also occur soon after a heart attack.
Risk factors for unstable angina are similar to those for stable angina and coronary artery disease, including:
Occasionally, sudden overwhelming stress can precipitate an episode of angina.
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Definition Unstable Angina Overview, Causes, & Risk Factors Unstable Angina Symptoms & Signs Unstable Angina Prevention Unstable Angina Diagnosis & Tests Unstable Angina Treatment Unstable Angina Prognosis Unstable Angina Complications Calling Your Health Care Provider
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Topics that might be of interest to you Diseases & Conditions
Angina Angina - Stable Arrhythmias Blood Clots Coronary Artery Spasm Diabetes Heart Attack Lipid Disorders - Acquired
Tests & Exams
Blood Pressure Coronary Angiography ECG HDL LDL Platelet Count
Surgery & Procedures
Angioplasty Heart Bypass Surgery
Other Topics
Chest Pain Cholesterol High Blood Pressure Obesity Physical Examination Stress and Anxiety
Review Date : 5/8/2002
Reviewed By : Elena Sgarbossa, M.D., Department of Cardiology, Rush-Presbyterian St. Luke's Medical Ctr., Chicago, IL. Review provided by VeriMed Healthcare Network.
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