Angina is chest pain or discomfort that occurs when there is too
little blood flowing to the heart muscle. It is often the result of
coronary artery disease and narrowing of the blood
vessels that supply the heart muscle.
There are several types of angina. The most common type is
stable angina, which occurs at predictable times with a
specific amount of exertion or activity. It is relieved by rest and may
continue without much change for years.
Unstable angina is a change in the usual
pattern of stable angina or a new severe angina that means blood flow has
decreased. In
unstable angina, chest pain occurs at rest or with
less and less exertion, may be more severe and last longer, or no longer
responds to nitroglycerin.
Angina caused by coronary artery spasms
results from a coronary artery that suddenly contracts (spasms), reducing
oxygen-rich blood flow to the heart. If severe, a spasm can block blood flow
and cause a heart attack. Most of the time coronary artery disease is involved,
although sometimes
plaque is not present. Cocaine can cause coronary
artery spasm and heart attack, but in most cases it is not known what triggers
them.
Variant angina, also called Prinzmetal's
angina or vasospastic angina, is also caused by coronary artery spasm. However,
it has a distinctive pattern. It usually occurs when you are at rest and
without apparent cause. It occurs more often at night, in the early morning
hours, or at the same time of the day. The spasm often occurs at the site of
coronary artery narrowing from plaque, although it can also occur in healthy
coronary arteries. Variant angina episodes typically last 2 to 5 minutes and
quickly subside with nitroglycerin.
Abnormal heartbeats, such as ventricular tachycardia,
often occur during variant angina episodes and may cause fainting.