Definition:
Angina is the name given to the symptoms (usually chest pain or chest discomfort) produced when the heart muscle is in a state of ischemia - that is, when the heart muscle is not getting enough blood supply. In unstable angina, ischemia occurs unpredictably and suddenly, usually because a blood clot has suddenly formed within a coronary artery, temporarily limiting blood flow to the heart muscle.
Unstable angina is often exacerbated by the formation of temporary blood clots within the coronary arteries. If the blood clots persist, a heart attack can occur. It's not surprising, then, that unstable angina often occurs before a heart attack, and should be treated aggressively.
Also Known As: atypical angina, rest angina
