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Overview of Coronary Artery Disease (CAD)


The Manual's Editorial Staff

Last full review/revision May 2021| Content last modified May 2021
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What is coronary artery disease?

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.

Coronary artery disease (heart disease) happens when blood flow through the coronary arteries is partially or totally blocked.

  • Coronary artery disease is the main cause of angina, unstable angina, and heart attack

  • You're more likely to have coronary artery disease if you're older, male, or have a parent or grandparent who had coronary artery disease before they were 50

  • The most common cause is hardening of the arteries (atherosclerosis)

Unstable angina and heart attack can cause an abnormal heart rhythm or cause your heart to stop. You can die if you aren't treated quickly. Also, a heart attack causes permanent heart damage.

Supplying the Heart With Blood

Like any other tissue in the body, the muscle of the heart must receive oxygen-rich blood and have waste products removed by the blood. The right coronary artery and the left coronary artery, which branch off the aorta just after it leaves the heart, deliver oxygen-rich blood to the heart muscle. The right coronary artery branches into the marginal artery and the posterior interventricular artery, located on the back surface of the heart. The left coronary artery (typically called the left main coronary artery) branches into the circumflex and the left anterior descending artery. The cardiac veins collect blood containing waste products from the heart muscle and empty it into a large vein on the back surface of the heart called the coronary sinus, which returns the blood to the right atrium.

Supplying the Heart With Blood

What causes coronary artery disease?

The most common cause of coronary artery disease is atherosclerosis, commonly known as hardening of the arteries. In atherosclerosis, cholesterol and other fatty material slowly build up in your arteries. This build-up is called an atheroma or plaque. The plaque may:

  • Narrow the artery, partly blocking blood flow to your heart

  • Rupture suddenly, causing a blood clot that blocks the artery and causes a heart attack

Less common causes include a sudden spasm of a coronary artery, usually from using drugs such as cocaine. During a spasm, the artery suddenly squeezes shut. If it stays shut long enough, you can have a heart attack. Usually the spasm stops and the artery opens up again.

What are the risk factors for coronary artery disease?

Risk factors that you can control or avoid:

Risk factors that are important but can't be controlled:

  • Having people in your family who had coronary artery disease before age 55

  • Being a man

  • Growing older

How can doctors tell if I have coronary artery disease?

Your doctor will ask you questions about your symptoms and do a physical exam and blood tests.

If you have symptoms of a blocked artery, your doctor may do tests:

  • Stress test—a test to see whether your heart is getting enough blood when it works hard (is under stress), such as when you exercise

  • ECG/EKG—a test that measures your heart’s electrical activity, which can be abnormal in coronary artery disease

  • Cardiac catheterization—a test that allows doctors to see if and where your coronary arteries are blocked by putting a long, thin catheter (small flexible tube) into an artery in your arm or leg, up to your heart, and into your coronary arteries

  • CT scan—an imaging test to look for hardening of the coronary arteries

How do doctors treat coronary artery disease?

Doctors treat the problem that's causing your coronary artery disease, which is usually hardening of the arteries. They may:

  • Give you medicine to lower the workload on your heart, such as blood pressure medicine

  • Give you medicine to lower your cholesterol level

  • Ask you to change any unhealthy behaviors that may hurt your heart—for example, smoking, not exercising, and eating a poor diet

  • Sometimes do a procedure to open a blocked artery

Depending on how much your coronary arteries are blocked, doctors may do a procedure to clear your artery. They may do angioplasty or bypass surgery (also called coronary artery bypass grafting or coronary artery bypass surgery).

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

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

How can I prevent or reverse coronary artery disease?

Change behaviors that may hurt your heart

  • Stop smoking—this is the most important way to prevent or reverse coronary artery disease

  • 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're overweight

  • Stay active by using weights or walking

  • Stop using drugs—this can be 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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