What happens?
Coronary arteries supply your heart with blood rich in oxygen. When the coronary arteries become narrowed, the amount of blood available to the heart muscle decreases. In other words, your heart muscle is not supplied with as much oxygen as it may need to beat regularly.

Under normal circumstances, the heart is able to compensate for this decreased blood flow. However, when you are exercising or are under emotional stress, your heart may need more oxygen to work properly. When parts of the heart muscle are deprived of the oxygen they need, that condition is called ischemia. It is the temporary loss of adequate blood supply.

What does it feel like?
The symptoms of angina vary from one person to another and may include any or all of the following: 

• Uncomfortable chest pressure, tightening, squeezing, aching, fullness, burning or "indigestion" usually felt behind the breastbone
• Pain or discomfort that starts in or spreads to the neck, jaw, teeth or arms
• Choking sensation
• Nausea and/or vomiting
• Sweating
• Palpitations (fluttering in the chest)
• Weakness
• Shortness of breath

Pain that is not typically associated with angina may feel:

• Sharp
• Stabbing
• Fleeting
• Localized to an area that can be pointed to with one finger
• Varying with breathing or changes in position

Angina can further be described as either stable or unstable. Stable angina is predictable. A person with stable angina can predict what activities or events will result in symptoms. When symptoms increase in severity or frequency or when they occur at rest, it is termed unstable angina. 

What should I do?
If symptoms of angina occur, the following actions should be taken

• Stop the activity
• Rest in a comfortable position
• If prescribed, place a tablet of nitroglycerin under the tongue
• If symptoms continue, nitroglycerin can be repeated every three-to-five minutes, up to a total of three tablets
• If symptoms are not relieved after 15 minutes of rest or taking three nitroglycerin tablets, call the local emergency medical system (911) immediately. Do not attempt to drive to the hospital.