Angina is pain or discomfort in the chest. It often has a squeezing or pressure-like feel. This discomfort can also be felt in the shoulders, arms, neck, jaws, or back. Anginal pain usually lasts for no more than 2-10 minutes. It is relieved by rest or nitroglycerin.

Types of angina include:
Stable angina —Has a predictable pattern. You generally know what brings it on and relieves it. You may also know what the intensity will be.

Unstable angina —Is more unpredictable and/or severe. Chest pain may occur while resting or even sleeping (nocturnal angina). The discomfort may last longer and be more intense than that of stable angina.

Unstable angina may be a sign that you are about to have a heart attack. It should be treated as an emergency.

Variant or Prinzmetal's angina —Caused by temporary spasm (contraction) of coronary arteries. Occurs when you are at rest, most often in the middle of the night. It can be quite severe.

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