Atherosclerosis is the hardening and narrowing of the arteries. It is caused by the slow buildup of plaque on the inside of walls of the arteries. Arteries are blood vessels that carry oxygen-rich blood from the heart to other parts of the body.
Plaque is made up of fat, cholesterol, calcium, and other substances found in the blood. As it grows, the buildup of plaque narrows the inside of the artery and, in time, may restrict blood flow. There are two types of plaque:
- Hard and stable
- Soft and unstable
Hard plaque causes artery walls to thicken and harden. Soft plaque is more likely to break apart from the walls and enter the bloodstream. This can cause a blood clot that can partially or totally block the flow of blood in the artery. When this happens, the organ supplied by the blocked artery starves for blood and oxygen. The organ's cells may either die or suffer severe damage.
Atherosclerosis is a slow, progressive disease that may start in childhood. It can affect the arteries of the brain, heart, kidneys, and the arms and legs. As plaque builds up, it can cause serious diseases and complications. These include:
- Coronary artery disease
- Heart attack
- Sudden death
- Cerebrovascular disease
- Transient ischemic attack (TIA) or "mini strokes"
- Peripheral arterial disease
Diseases caused by atherosclerosis are the leading cause of illness and death in the United States.
Atherosclerosis usually does not cause symptoms until it:
- Severely narrows an artery
- Totally blocks an artery
Symptoms you may have depend on which arteries are severely narrowed or blocked.
- If the arteries that feed your heart (coronary arteries) are affected, you have symptoms of coronary artery disease.
- If the arteries that feed your brain are affected, you have symptoms of a stroke or a transient ischemic attack (TIA) or "mini stroke."
- If the arteries that feed your legs, pelvis, or arms are affected, you have symptoms of peripheral arterial disease.
- If the arteries that feed your kidneys are affected, you have symptoms of renovascular hypertension.
Atherosclerosis is often diagnosed after you develop symptoms or complications. To make a diagnosis, your doctor will:
- Ask about your health history and risk factors
- Ask about your family history of atherosclerosis or its complications
- Do a physical exam
- Do certain tests to identify atherosclerosis or its complications
The physical exam may include:
- Listening to your arteries for an abnormal whooshing sound, called a bruit. A bruit can be heard with a stethoscope when placed over the affected artery.
- Checking to see if any of your pulses (for example, in the leg or foot) are weak or absent.
Tests your doctor may do include:
- Blood work to check your:
- Cholesterol levels
- Blood glucose (sugar) level to screen for diabetes
- EKG (electrocardiogram) to measure the rate and regularity of your heartbeat and show evidence of a minor heart attack.
- Chest x ray, which provides a picture of the lungs, heart, large arteries, ribs, and the diaphragm.
- Ankle/brachial index, which compares the blood pressure in your ankle with the blood pressure in your arm.
- Echocardiogram. This test uses sound waves to create a moving picture of your heart. Echocardiogram provides information about the size and shape of your heart and how well your heart chambers and valves are functioning. The test also can identify areas of poor blood flow to the heart, areas of heart muscle that are not contracting normally, and previous injury to the heart muscle caused by poor blood flow.
- There are several different types of echocardiograms, including a stress echocardiogram. During this test, an echocardiogram is done both before and after your heart is stressed either by having you exercise or by injecting a medicine into your bloodstream that makes your heart beat faster and work harder. A stress echocardiogram is usually done to find out if you have decreased blood flow to your heart (coronary artery disease).
- CT scan, which provides computer-generated images of the heart, brain, or other areas of interest.
- Angiography, a test that allows your doctor to look inside your arteries to see if there is any blockage and how much. A thin flexible tube is passed through an artery in the upper leg (groin) or in the arm to reach the arteries that may be blocked. A dye that can be seen on x ray is injected into the arteries. Using an x ray, your doctor can see the flow of blood through your arteries.
- Stress Test. Some heart problems are easier to diagnose when your heart is working harder and beating faster than when it’s at rest. During stress testing, you exercise (or are given medicine if you are unable to exercise) to make your heart work harder and beat faster while heart tests are performed.
- During exercise stress testing, your blood pressure and EKG readings are monitored while you walk or run on a treadmill or pedal a bicycle. Other heart tests, such as nuclear heart scanning or echocardiography, also can be done at the same time. These would be ordered if your doctor needs more information than the exercise stress test can provide about how well your heart is working.
- If you are unable to exercise, a medicine can be injected through an intravenous line (IV) into your bloodstream to make your heart work harder and beat faster, as if you are exercising on a treadmill or bicycle. Nuclear heart scanning or echocardiography is then usually done.
- During nuclear heart scanning, radioactive tracer is injected into your bloodstream, and a special camera shows the flow of blood through your heart and arteries. Echocardiography uses sound waves to show blood flow through the chambers and valves of your heart and to show the strength of your heart muscle.
- Your doctor also may order two newer tests along with stress testing if more information is needed about how well your heart works. These new tests are magnetic resonance imaging (MRI) and positron emission tomography (PET) scanning of the heart. MRI shows detailed images of the structures and beating of your heart, which may help your doctor better assess if parts of your heart are weak or damaged. PET scanning shows the level of chemical activity in different areas of your heart. This can help your doctor determine if enough blood is flowing to the areas of your heart. A PET scan can show decreased blood flow caused by disease or damaged muscles that may not be detected by other scanning methods.
The goals of treatment are to reduce the symptoms and prevent the complications of atherosclerosis. Your doctor will recommend which treatments are best for you after reviewing your symptoms, your risk factors, and the results of your physical exam and any lab tests. Treatment can include:
- Lifestyle changes
- Special procedures and surgery
Most people with atherosclerosis should make certain, long-term lifestyle changes:
- Eat a healthy diet.
- A low-saturated fat, low-cholesterol diet (TLC diet)
- A diet lower in salt, total fat, saturated fat, and cholesterol and higher in fruits, vegetables, and low-fat dairy products (DASH Eating Plan)
- If you smoke or use tobacco, quit.
- Physical activity, as directed by your doctor.
- Lose weight, if you are overweight or obese.
To help slow or reverse atherosclerosis, you may need to take medicines as directed by your doctor to:
- Lower your cholesterol
- Lower your blood pressure if you have high blood pressure
- Prevent clots from forming in your arteries and blocking blood flow (anticoagulants)
- Stop platelets from clumping together to form clots (antiplatelet medicines such as aspirin)
Special Procedures and Surgery
Some people may need to have one of the following procedures to treat the complications of atherosclerosis:
- Angioplasty. This procedure is used to open blocked or narrowed coronary arteries. It can improve blood flow to your heart, relieve chest pain, and possibly prevent a heart attack. Sometimes a stent is placed in the artery to keep it propped open after the procedure.
- Coronary artery bypass surgery. This surgery uses arteries or veins from other areas in your body to bypass your diseased coronary arteries. It can improve blood flow to your heart, relieve chest pain, and possibly prevent a heart attack.
- Carotid artery surgery. This surgery removes plaque buildup from the carotid artery in the neck. This opens the artery and improves blood flow to the brain.
- Bypass surgery of the leg arteries. This surgery uses a healthy blood vessel to bypass the narrowed or blocked blood vessels. The healthy blood vessel redirects blood around the blocked artery, improving blood flow to the leg.
Prevention / Risk Factors
Scientists don't know exactly how atherosclerosis begins or the exact cause. It is a slow and complex disease that may start in childhood. In some people, atherosclerosis develops faster as they grow older.
Scientists think that the buildup of plaque starts when the lining of the artery is damaged or injured. Research continues to find out:
- Why and how the arteries become damaged
- How plaque develops and changes over time
- Why plaque can break open and lead to clots
Although scientists don't know the exact cause, they do know that certain conditions increase your chance of developing atherosclerosis. They are called risk factors. Your chance of having atherosclerosis increases with the number of risk factors you have. You can control some risk factors and others you can't.
Risk factors that you can't do anything about are:
- Age. As you get older, your risk increases.
- In men, risk increases after age 45.
- In women, risk increases after age 55.
- Family history of early heart disease. Your risk for atherosclerosis is greater if:
- Your father or brother was diagnosed with heart disease before age 55.
- Your mother or sister was diagnosed with heart disease before age 65.
Risk factors that you can do something about include:
- High blood cholesterol
- High blood pressure
- Smoking and using tobacco
- Lack of physical activity
Preventing atherosclerosis starts by knowing which risk factors you have and by taking action to lower your risk. Atherosclerosis is a slow process that starts in childhood and continues as you get older.
Know your family history of health problems related to atherosclerosis. If you or someone in your family has atherosclerosis, be sure to tell your doctor. Make sure everyone in your family is getting enough exercise and maintaining a healthy body weight.
By controlling your risk factors with lifestyle changes and medicines, you may prevent or slow the development of atherosclerosis.
If you have any other health conditions, it is important that you follow your doctor's directions to treat them. By staying as healthy as possible, you can lower your risk for getting atherosclerosis and prevent serious complications, such as a heart attack.