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Quick Facts

Unstable Angina


The Manual's Editorial Staff

Last full review/revision May 2021| Content last modified May 2021
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What is unstable angina?

Angina is pain, discomfort, or pressure in your chest that happens when your heart isn't getting enough oxygen. The lack of oxygen is caused by a narrow or blocked artery to your heart (coronary artery disease). Angina usually comes when you exert yourself, for example, by climbing stairs or walking up a hill. It goes away in a few minutes when you rest. You usually get angina each time you do the same amount of exertion.

Unstable angina is when your angina comes:

  • With much less exertion than normal

  • When you aren't exerting yourself at all

With unstable angina:

  • You have chest pain or pressure

  • Doctors do blood tests and ECG/EKG

  • Doctors will give you medicine and do procedures to try to get more blood to the affected area of your heart

What causes unstable angina?

The heart is a muscle that pumps blood. Like all muscles, the heart needs a steady supply of blood to work. Blood that pumps through the heart doesn't feed the heart muscle. Instead, the heart muscle is fed by its own arteries. These arteries are called coronary arteries. Coronary is a word for heart.

Unstable angina happens when one of your coronary arteries is temporarily blocked by a blood clot.

If the blood clot goes away on its own, your symptoms go away. If the blood clot doesn't go away quickly, you will have a heart attack. In a heart attack, the affected heart muscle dies because it doesn't get enough blood. In unstable angina, the affected muscle doesn't die. However, unstable angina is a warning sign of a heart attack.

Blood clots in a coronary artery usually happen when you have atherosclerosis:

  • Atherosclerosis is commonly known as hardening of the arteries

  • Atherosclerosis is the slow build-up of cholesterol and other fatty material in your arteries

  • This build-up is called an atheroma or plaque

  • The plaque may rupture suddenly, causing a blood clot that blocks the artery

With unstable angina, your heart's rhythm may also be affected, causing it to beat too fast or too slow. Rarely, your heart stops completely (cardiac arrest) and you die.

What are the symptoms of unstable angina?

Symptoms of unstable angina are similar to angina, but the pain usually hurts more, lasts longer, and doesn't feel better with rest.

  • You may have pain in the middle of your chest

  • The pain may spread to your back, jaw, or left arm

  • Less often, the pain spreads to the right arm

  • The pain may occur in one or more of these places and not in your chest at all

  • You may feel sweaty and nervous

  • Your lips, hands, or feet may turn slightly blue

How can doctors tell if I have unstable angina?

Doctors base the diagnosis on your symptoms and do tests, such as:

  • ECG/EKG—a test that measures your heart’s electrical activity

  • Blood tests to check for certain substances that show heart problems

How do doctors treat unstable angina?

You will be admitted to the hospital. Doctors will:

  • Control your heart rhythm and blood pressure

  • Give you nitroglycerin under your tongue and by vein to relieve chest pain

  • Give you medicines to prevent blood clots

  • Give you medicines to lower the work load on your heart

  • Sometimes do a procedure (angioplasty) to open up the blocked artery

During angioplasty:

  • The doctor puts a small, flexible tube (catheter) into an artery in your upper leg (groin) or in your wrist

  • The catheter is pushed up the artery to your heart and then into one of your coronary arteries

  • A small balloon on the tip of the catheter is inflated

  • The balloon pushes the blockage open

  • Then the doctor slips a wire mesh tube (stent) off the end of the catheter into the blocked area

  • The wire mesh tube helps hold the blocked area open

Sometimes doctors can't do angioplasty. They may recommend bypass surgery (also called coronary artery bypass grafting or coronary artery bypass surgery).

During bypass surgery:

  • Doctors take a piece of healthy artery or vein from another part of your body

  • They sew one end of that piece of artery or vein to your aorta (the major artery that takes blood from your heart to the rest of your body)

  • They sew the other end to your blocked artery past the point of the blockage

  • Your blood then flows through this new route, bypassing the blockage

Treat the cause of your unstable angina

To treat the problem that caused your unstable angina, doctors usually give you:

They'll also have you change any behaviors that are hurting your heart, such as smoking, not exercising, and eating a poor diet.

How can I prevent unstable angina?

Change behaviors that may hurt your heart

  • Eat healthy foods, such as fresh fruits and vegetables and other high-fiber foods

  • Eat less fat from meats, dairy, and processed foods (such as frozen pizza or microwaveable dinners)—talk to your doctor about how much and which types of fat you should eat

  • Lose weight if you need to

  • Stay active by using weights or walking

  • Stop smoking or using drugs—this can be a hard to stop, so talk to your doctor or a counselor about how to get help

Take your medicines correctly

  • Remember to take any medicines prescribed by your doctor, such as for high cholesterol, high blood pressure, or diabetes

  • If you're 50 or older, ask your doctor about taking a low dose of aspirin every day to help prevent heart attacks and strokes

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