Angina "angina pectoris" - (Latin for squeezing of the chest) is a chest discomfort that occurs when there is a decreased blood oxygen supply to an area of the heart muscle. In most cases, lack of blood supply is due to a narrowing of the coronary arteries as a result of arteriosclerosis.

Stable angina is a most common type of angina, and what most people mean when they are refer to angina. People with stable angina have angina symptoms on a regular basis and the symptoms are somewhat predictable as example, walking up a flight of steps causes chest pain. For most patients, symptoms occur during exertion and commonly last less than five minutes. They are relieved by rest or medication, such as nitroglycerin under the tongue.

Unstable angina is less common and more serious. The symptoms are more severe and less predictable than the pattern of stable angina. Moreover, the pains are more frequent, last longer, occur at rest, and are not relieved by nitroglycerin under the tongue. Unstable angina is not the same as a heart attack, but it warrants an immediate visit to your healthcare provider or hospital emergency department as further cardiac testing is urgently needed. Unstable angina is often a precursor to a heart attack.

The most common cause of angina is a coronary artery disease. A less common cause of angina is spasm of the coronary arteries.

The walls of the arteries are surrounded by muscle fibers. Rapid contraction of these muscle fibers causes a sudden narrowing (spasm) of the arteries. A spasm of the coronary arteries reduces blood to the heart muscle and causes angina. Angina as a result of a coronary artery spasm is called "Variant" angina or Prinzmetal angina. Prinzmetal angina typically occurs at rest, usually in the early morning hours. Spasms can occur in normal coronary arteries as well as in those narrowed by arteriosclerosis. Coronary artery spasm can also be caused by use/abuse of cocaine. The spasm of artery wall caused by the cocaine can be so significant that it can actually cause a heart attack.