Angina (AN-juh-nuh or an-JIE-nuh) is chest pain caused by a reduction in blood flow to the heart muscle.

What Is Angina?

Angina or angina pectoris is a type of chest pain that occurs when blood flow to the heart muscle does not meet the muscle's demand for oxygen. The heart muscle cannot survive without a consistent supply of oxygenated blood, so when the blood flow or oxygen level is lower than what the heart muscle needs, the muscle reacts by causing pain.

Some people experience angina with exercise or emotional stress. It is also commonly identified as being a side effect of abusing stimulants like cocaine. Medical problems that can cause angina to occur include the following:

Why Does Angina Occur?

The heart muscle needs a constant supply of oxygenated blood * . If this supply is insufficient in any way, the heart muscle becomes ischemic (having a reduced supply of nutrients as well as oxygen). Reductions in cardiac blood flow can occur from an obstruction in one of the vessels that supply the heart with blood; a spasm in a vessel; or a blockage or thrombus (clot).

When the blood supply to the heart is inadequate, cellular processes change from aerobic metabolism * to anaerobic metabolism * . This change in metabolism causes a buildup of lactic acid *

CCS Angina Grading Scale

Angina is graded by severity:

  • Class I: does not occur with routine activity but rather with strenuous, rapid, or prolonged physical activity.
  • Class II: may occur with rapid or prolonged walking or climbing stairs.
  • Class III: the person's physical activity is severely limited.
  • Class IV: chest pain occurs at rest and with any type of activity.

SOURCE: Canadian Cardiovascular Society (CCS).

What Are the Types of Angina?

There are three different types of angina:

  1. Stable. Stable angina is the most common type because it is predictable. It occurs when the same activity is performed or stress is experienced. The situations in which stable angina most commonly occurs include exercise, exposure to cold, and stress. It is relieved by rest and, in many cases, the medication nitroglycerin.
  2. Prinzmetal's (variant). Prinzmetal's (PRINCE-mett-les) or variant angina is unpredictable. It can occur at any time and during any activity. It usually occurs at night and has been linked to a spasm in a coronary artery. The exact reason for coronary artery spasms is unknown; however, doctors think they may be caused by an overactive nervous system and changes in cardiac cell responses to blood electrolytes and hormones.
  3. Unstable angina. Unstable angina is also unpredictable and occurs more frequently. The pain is increasingly more severe and lasts longer each time. It can occur with activity, stress, or at rest. Individuals with this type of angina are at risk of developing a myocardial infarction or heart attack.

What Does Angina Feel Like?

The main symptom of angina is chest pain. The pain is usually associated with a predictable event, such as excessive physical activity, strong emotional arousal, eating a heavy meal, or exposure to cold. The sequence of events with angina usually is some activity; pain occurs; immediate rest; pain is relieved.

Those who experience angina describe the pain as being tight, squeezing, a heavy pressure, or a constricting sensation. It usually begins below the sternum (breastbone) and then moves or radiates to the jaw, neck, shoulder, or arm. Some people have experienced the pain of angina in the back, along with nausea and vomiting. Other symptoms that occur with the chest pain include dyspnea * , pallor, tachycardia * , anxiety, and fear.

How Is Angina Identified?

Any type of chest pain should never be ignored. When chest pain occurs, the person should go to the nearest emergency department for evaluation and treatment. The cause of the chest pain will be analyzed; diagnosis usually includes the following types of tests:

* or lacking in adequate blood flow. This test is usually done on people who are unable to walk on the treadmill to complete a stress electrocardiogram.
  • Echocardiogram: An echocardiogram is the use of an ultrasound to evaluate the structure and functions of the heart. It looks at each of the heart chambers and valves, and how the heart functions with each heartbeat.
  • Coronary angiogram: A coronary angiogram (or cardiac catheterization) is the introduction of a catheter * into the vessels that feed the heart muscle. This test is considered the gold standard for finding out why a person is experiencing chest pain.

    Nitroglycerin (NTG) is the drug of choice for treating chest pain. It is usually taken sublingually (in the mouth under the tongue) and permitted to dissolve. Individuals who are prescribed NTG for chest pain are instructed to take one tablet and wait five minutes, then repeat the dose and wait another five minutes. If the pain continues, a third NTG tablet can be taken. If the pain continues after three doses, the person should seek immediate medical attention.

    These tablets are very sensitive to light and should be kept in the original amber bottle obtained from the pharmacy. They are not to be transferred to another type of pill holder and must be protected from extreme temperatures. They should not be stored in the refrigerator or in the medicine cabinet in the bathroom. The bottle should be replaced every six months.

    The person taking a NTG tablet should be instructed not to eat, drink, or smoke until the tablet is completely dissolved. The person might experience a slight tingling sensation under the tongue while the tablet is dissolving. This sensation is expected and is considered normal. The person might complain of a headache after taking NTG. This reaction is normal and is caused by the dilation (expansion) of blood vessels. The headache will decrease in a short while.

    Antiangina drugs

    Antiangina drugs
    Table by PreMediaGlobal. © 2016 Cengage Learning®.

    How Is Angina Treated?

    After the diagnosis of angina is made, the health care provider will determine which class of medication to prescribe. Three major classifications of medications are used to control the pain:

    Aspirin is often prescribed for individuals with angina to reduce the risk of blood clotting in the event of a myocardial infarction. The usual dosage is 75 to 81 mg to be taken every day.

    Can Angina Be Prevented?

    The best way to prevent the development of angina is to engage in heart-healthy activities and follow a healthful diet. Regular aerobic exercise should be performed after receiving clearance from a health care provider. Exercise strengthens the heart muscle, improves blood flow, reduces blood pressure, and helps maintain a healthy body weight.

    A healthful diet reduces the intake of saturated fats and limits or eliminates the intake of trans fats, while supplying the recommended amount of vitamins, minerals, and calories to achieve or maintain a healthful body weight.

    Individuals identified as having elevated cholesterol or triglyceride levels should discuss medication therapy with a health care provider. Additional actions to reduce the risk of angina include stress reduction activities and smoking cessation if appropriate.

    See also Anemia, Bleeding, and Clotting • Arteriosclerosis/Atherosclerosis • Heart Attack (Myocardial Infarction) • Heart Disease (Overview) • Hypertension • Thyroid Disease


    Books and Articles

    Aaronson, Philip I., Jeremy P. T. Ward, and Michelle J. Connolly. The Cardiovascular System at a Glance. 4th ed. Malden, MA: Wiley-Blackwell, 2013.

    Jevon, Phil. Angina and Heart Attack. New York: Oxford University Press, 2012.


    Heart Foundation. “Angina.” (accessed March 21, 2016).

    National Heart, Lung, and Blood Institute. “What Is Angina?” (accessed March 21, 2016).


    American College of Cardiology. Heart House, 2400 N Street NW, Washington, DC 20037. Toll-free: 800-253-4636, ext. 5603. Website: (accessed March 21, 2016).

    American Heart Association. 7272 Greenville Ave., Dallas, TX 752314596. Telephone: 214-373-6300. Toll-free: 800-242-8721. Website: (accessed March 21, 2016).

    * atherosclerosis is a disease in which plaque builds up inside the blood vessels that carry oxygen-rich blood to the heart and rest of the body.

    * thyrotoxicosis refers to an excessive amount of circulating thyroid hormone. It is not synonymous with hyperthyroidism, as increased levels of hormone can occur despite otherwise normal thyroid function.

    * hyperthyroidism (HI-per-THY-roydih-zum) is excessive activity of the thyroid gland, characterized by an enlarged thyroid gland, increased metabolic rate, rapid heartbeat, and high blood pressure.

    * anemia (uh-NEE-me-uh) is a blood condition in which there is decreased hemoglobin in the blood and usually a lower than normal number of red blood cells.

    * heart failure is a condition in which a damaged heart cannot pump enough blood to meet the oxygen and nutrient demands of the body. Also called congestive heart failure.

    * cardiomyopathy (KAR-dih-oh-my-OP-ah-thy) is a chronic disease of the heart muscle, in which the muscle is abnormally enlarged, thickened, and/or stiffened.

    * pulmonary diseases are any abnormal condition of the respiratory system, characterized by cough, chest pain, mucus production, or harsh, vibrating, crackling, or wheezing sounds while breathing.

    * oxygenated blood is blood carrying oxygen for circulation throughout the body.

    * lactic acid is a compound primarily produced by muscle tissue and red blood cells as carbohydrates are metabolized when oxygen levels are low.

    * anaerobic (an-air-OH-bik) metabolism extracts energy from only carbohydrate sources without the presence of oxygen to facilitate the reaction.

    * aerobic (air-OH-bik) metabolism uses oxygen to extract energy from carbohydrate sources, fatty acids and amino acids

    * dyspnea is difficult or labored breathing; shortness of breath.

    * tachycardia is an elevated or very fast heartbeat.

    * ischemic (is-KEE-mik) refers to an area or organ of the body that is lacking in adequate blood flow, often due to a tightening of or obstruction in blood vessels.

    * catheter (KAH-thuh-ter) is a small plastic tube placed through a body opening into an organ (such as the bladder) or through the skin directly into a blood vessel. It is used to give fluids to or drain fluids from a person.

    Disclaimer:   This information is not a tool for self-diagnosis or a substitute for professional care.

    (MLA 8th Edition)