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Angina Pectoris, Unstable

Basic Facts

  • Angina pectoris results from a condition called coronary heart disease, an accumulation of plaque inside the coronary blood vessels that reduces blood flow to the heart.
  • The pain or tightness associated with angina results from ischemia, the lack of oxygenated blood reaching the heart.
  • Angina experienced at rest is called unstable angina because of the unpredictable onset of heart pain.
  • Unstable angina may feel like a heart attack but does not last as long and does not damage the heart.
Angina pectoris is chest pain or discomfort. A person may feel pain when insufficient oxygen-rich blood reaches the heart muscle. This reduced blood flow is caused by coronary heart disease (CHD), an accumulation of plaque inside the coronary blood vessels.

Plaque buildup blocking normal blood flow. More rarely, an artery 'spasm' can block the flow of blood through an artery, causing angina pain.
Plaque buildup blocking normal blood flow. More rarely, an artery 'spasm' can block the flow of blood through an artery, causing angina pain.
Angina that occurs unpredictably or during rest is called unstable angina. Sometimes, unstable angina can result from a temporary blood clot that suddenly blocks blood flow to the heart. The pain subsides when the clot dissolves and blood flow resumes.

If a person has experienced angina after exertion, called stable angina, and angina symptoms begin to last after exercise or occur at rest, the angina may have become unstable angina. This usually means an artery has narrowed further, often because of a blood clot. If an episode of unstable angina is the first instance of angina a person experiences, it is called new onset unstable angina.


Typical angina pain.
Typical angina pain.
Pain associated with unstable angina usually lasts between 5 and 30 minutes. When chest pain lasts more than 20 minutes, it may be a heart attack and not angina. The symptoms associated with angina can vary from person to person, and can include:
  • Chest pain, tightness, or pressure;
  • A heavy, crushing feeling in the chest;
  • Discomfort just below the breastbone;
  • A burning feeling similar to heartburn or indigestion;
  • A sensation of heaviness in the chest, or in the neck, throat, jaw, shoulder and arm; and
  • Shortness of breath.
Angina can sometimes cause nausea, lightheadedness, or profuse sweating. Because unstable angina occurs without warning, it can cause severe anxiety.


People with a family history of CHD or stroke may be more likely to develop unstable angina than people whose families do not have these conditions.

Other risks for unstable angina are related to lifestyle, including:
  • Smoking;
  • High cholesterol;
  • Sedentary lifestyle;
  • High blood pressure;
  • Eating a high-fat, high-cholesterol diet;
  • Having diabetes;
  • Being more than 30 percent overweight; and
  • Using cocaine or other recreational drugs.

A physician diagnoses angina by performing a careful medical history and physical examination. Because their symptoms are similar, the physician will attempt to rule out a heart attack by ordering tests, including:
  • Resting electrocardiogram (ECG);
  • Blood tests;
  • Cardiac catheterization and angiography;
  • ECG stress test;
  • Nuclear stress test; and
  • Echocardiographic stress test.

The principal goal of therapy for unstable angina is to restore normal blood supply to the heart.

A physician may prescribe aspirin or stronger medications to people who experience unstable angina to reduce the formation of blood clots in the coronary arteries and restore normal blood flow. A person who experiences unstable angina, and who is not taking aspirin, should immediately chew an aspirin to achieve an anti-clotting effect.

If unstable angina persists, the person should immediately seek medical attention at a hospital. At the hospital, a person may be given drugs by mouth or intravenously, such as:
  • Aspirin;
  • Heparin, or other anti-clotting drugs; and
  • Nitroglycerin.
A physician may prescribe the following medications for long-term management of angina:
  • Nitrates (such as nitroglycerin);
  • Beta-blockers; and
  • Calcium channel blockers.
People who experience angina may also have to take medications to control cholesterol, blood pressure, and abnormal heart rhythms.

If the angina does not respond to medication, the physician may recommend surgical procedures, including:
  • Angioplasty and stenting: During this procedure, a balloon attached to a catheter is inflated and deflated within an artery to flatten the plaque and increase the artery's diameter. In most cases, a stent, a metal-mesh tube, is expanded and left inside the artery to support the expansion and maintain blood flow.
  • Coronary artery bypass graft (CABG). A physician replaces, or bypasses, the blocked artery with a healthy blood vessel harvested from a person's leg vein or chest artery.
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