What Is Atherosclerosis?

Atherosclerosis is a disease in which plaque builds up inside your arteries. Arteries are blood vessels that carry oxygen-rich blood to your heart and other parts of your body.

Plaque is made up of fat, cholesterol, calcium, and other substances found in the blood. Over time, plaque hardens and narrows your arteries. This limits the flow of oxygen-rich blood to your organs and other parts of your body.

Atherosclerosis can lead to serious problems, including heart attack, stroke, or even death.

Atherosclerosis

Figure A shows a normal artery with normal blood flow. Figure B shows an artery with plaque buildup.

Overview

The cause of atherosclerosis isn't known. However, certain traits, conditions, or habits may raise your risk for the disease. These conditions are known as risk factors.

You can control some risk factors, such as lack of physical activity, smoking, and an unhealthy diet. Others you can't control, such as age and a family history of heart disease.

Some people who have atherosclerosis have no signs or symptoms. They may not be diagnosed until after a heart attack or stroke.

The main treatment for atherosclerosis is lifestyle changes. You also may need medicines and medical procedures. These treatments, along with ongoing medical care, can help you live a healthier life.

Outlook

Improved treatments have reduced the number of deaths from atherosclerosis-related diseases. These treatments also have improved the quality of life for people who have these diseases. However, atherosclerosis remains a common health problem.

You may be able to prevent or delay atherosclerosis and the diseases it can cause. Making lifestyle changes and getting ongoing care can help you avoid the problems of atherosclerosis and live a long, healthy life.

What Causes Atherosclerosis?

The exact cause of atherosclerosis isn't known. However, studies show that atherosclerosis is a slow, complex disease that may start in childhood. It develops faster as you age.

Atherosclerosis may start when certain factors damage the inner layers of the arteries. These factors include:

• Smoking
• High amounts of certain fats and cholesterol in the blood
• High blood pressure
• High amounts of sugar in the blood due to insulin resistance or diabetes

Plaque may begin to build up where the arteries are damaged. Over time, plaque hardens and narrows the arteries. Eventually, an area of plaque can rupture (break open).

When this happens, blood cell fragments called platelets stick to the site of the injury. They may clump together to form blood clots. Clots narrow the arteries even more, limiting the flow of oxygen-rich blood to your body.

Depending on which arteries are affected, blood clots can worsen angina (chest pain) or cause a heart attack or stroke.

Researchers continue to look for the causes of atherosclerosis. They hope to find answers to questions such as:

• Why and how do the arteries become damaged?
• How does plaque develop and change over time?
• Why does plaque rupture and lead to blood clots?

Who Is at Risk for Atherosclerosis?

Coronary heart disease (atherosclerosis of the coronary arteries) is the #1 killer of both men and women in the United States.

The exact cause of atherosclerosis isn't known. However, certain traits, conditions, or habits may raise your risk for the disease. These conditions are known as risk factors. The more risk factors you have, the more likely it is that you'll develop atherosclerosis.

You can control most risk factors and help prevent or delay atherosclerosis. Other risk factors can't be controlled.

Major Risk Factors

• Unhealthy blood cholesterol levels. This includes high LDL cholesterol (sometimes called "bad" cholesterol) and low HDL cholesterol (sometimes called "good" cholesterol).
• High blood pressure. Blood pressure is considered high if it stays at or above 140/90 mmHg over time. If you have diabetes or chronic kidney disease, high blood pressure is defined as 130/80 mmHg or higher. (The mmHg is millimeters of mercury—the units used to measure blood pressure.)
• Smoking. Smoking can damage and tighten blood vessels, raise cholesterol levels, and raise blood pressure. Smoking also doesn't allow enough oxygen to reach the body's tissues.
• Insulin resistance. This condition occurs if the body can't use its insulin properly. Insulin is a hormone that helps move blood sugar into cells where it's used as an energy source. Insulin resistance may lead to diabetes.
• Diabetes. With this disease, the body's blood sugar level is too high because the body doesn't make enough insulin or doesn't use its insulin properly.
• Overweight or obesity. The terms "overweight" and "obesity" refer to body weight that's greater than what is considered healthy for a certain height.
• Lack of physical activity. A lack of physical activity can worsen other risk factors for atherosclerosis, such as unhealthy blood cholesterol levels, high blood pressure, diabetes, and overweight and obesity.
• Unhealthy diet. An unhealthy diet can raise your risk for atherosclerosis. Foods that are high in saturated and transfats, cholesterol, sodium (salt), and sugar can worsen other atherosclerosis risk factors.
• Older age. As you get older, your risk for atherosclerosis increases. Genetic or lifestyle factors cause plaque to build up in your arteries as you age. By the time you're middle-aged or older, enough plaque has built up to cause signs or symptoms. In men, the risk increases after age 45. In women, the risk increases after age 55.
• Family history of early heart disease. Your risk for atherosclerosis increases if your father or a brother was diagnosed with heart disease before 55 years of age, or if your mother or a sister was diagnosed with heart disease before 65 years of age.

Although age and a family history of early heart disease are risk factors, it doesn't mean that you'll develop atherosclerosis if you have one or both. Controlling other risk factors often can lessen genetic influences and prevent atherosclerosis, even in older adults.

Studies show that an increasing number of children and youth are at risk for atherosclerosis. This is due to a number of causes, including rising childhood obesity rates.

Emerging Risk Factors

Scientists continue to study other possible risk factors for atherosclerosis.

High levels of a protein called C-reactive protein (CRP) in the blood may raise the risk for atherosclerosis and heart attack. High levels of CRP are a sign of inflammation in the body.

Inflammation is the body's response to injury or infection. Damage to the arteries' inner walls seems to trigger inflammation and help plaque grow.

People who have low CRP levels may develop atherosclerosis at a slower rate than people who have high CRP levels. Research is under way to find out whether reducing inflammation and lowering CRP levels also can reduce the risk for atherosclerosis.

High levels of triglycerides in the blood also may raise the risk for atherosclerosis, especially in women. Triglycerides are a type of fat.

Studies are under way to find out whether genetics may play a role in atherosclerosis risk.

Other Factors That Affect Atherosclerosis

Other factors also may raise your risk for atherosclerosis, such as:

• Sleep apnea. Sleep apnea is a disorder that causes one or more pauses in breathing or shallow breaths while you sleep. Untreated sleep apnea can raise your risk for high blood pressure, diabetes, and even a heart attack or stroke.
• Stress. Research shows that the most commonly reported "trigger" for a heart attack is an emotionally upsetting event, especially one involving anger.
• Alcohol. Heavy drinking can damage the heart muscle and worsen other risk factors for atherosclerosis. Men should have no more than two drinks containing alcohol a day. Women should have no more than one drink containing alcohol a day.

What Are the Signs and Symptoms of Atherosclerosis?

Atherosclerosis usually doesn't cause signs and symptoms until it severely narrows or totally blocks an artery. Many people don't know they have the disease until they have a medical emergency, such as a heart attack or stroke.

Some people may have signs and symptoms of the disease. Signs and symptoms will depend on which arteries are affected.

Coronary Arteries

The coronary arteries supply oxygen-rich blood to your heart. If plaque narrows or blocks these arteries (a disease called coronary heart disease, or CHD), a common symptom is angina. Angina is chest pain or discomfort that occurs when your heart muscle doesn't get enough oxygen-rich blood.

Angina may feel like pressure or squeezing in your chest. You also may feel it in your shoulders, arms, neck, jaw, or back. Angina pain may even feel like indigestion. The pain tends to get worse with activity and go away with rest. Emotional stress also can trigger the pain.

Other symptoms of CHD are shortness of breath and arrhythmias. Arrhythmias are problems with the rate or rhythm of the heartbeat.

Plaque also can form in the heart's smallest arteries. This disease is called coronary microvascular disease (MVD). Symptoms of coronary MVD include angina, shortness of breath, sleep problems, fatigue (tiredness), and lack of energy.

Carotid Arteries

The carotid arteries supply oxygen-rich blood to your brain. If plaque narrows or blocks these arteries (a disease called carotid artery disease), you may have symptoms of a stroke. These symptoms may include:

• Sudden weakness
• Paralysis (an inability to move) or numbness of the face, arms, or legs, especially on one side of the body
• Confusion
• Trouble speaking or understanding speech
• Trouble seeing in one or both eyes
• Problems breathing
• Dizziness, trouble walking, loss of balance or coordination, and unexplained falls
• Loss of consciousness
• Sudden and severe headache

Peripheral Arteries

Plaque also can build up in the major arteries that supply oxygen-rich blood to the legs, arms, and pelvis (a disease called peripheral arterial disease).

If these major arteries are narrowed or blocked, you may have numbness, pain, and, sometimes, dangerous infections.

Renal Arteries

The renal arteries supply oxygen-rich blood to your kidneys. If plaque builds up in these arteries, you may develop chronic kidney disease. Over time, chronic kidney disease causes a slow loss of kidney function.

Early kidney disease often has no signs or symptoms. As the disease gets worse it can cause tiredness, changes in how you urinate (more often or less often), loss of appetite, nausea (feeling sick to the stomach), swelling in the hands or feet, itchiness or numbness, and trouble concentrating.

How Is Atherosclerosis Diagnosed?

Your doctor will diagnose atherosclerosis based on your medical and family histories, a physical exam, and test results.

Specialists Involved

If you have atherosclerosis, a primary care doctor, such as an internist or family practitioner, may handle your care. Your doctor may recommend other health care specialists if you need expert care, such as:

• A cardiologist. This is a doctor who specializes in diagnosing and treating heart diseases and conditions. You may go to a cardiologist if you have coronary heart disease (CHD) or coronary microvascular disease (MVD).
• A vascular specialist. This is a doctor who specializes in diagnosing and treating blood vessel problems. You may go to a vascular specialist if you have peripheral arterial disease (P.A.D.).
• A neurologist. This is a doctor who specializes in diagnosing and treating nervous system disorders. You may see a neurologist if you've had a stroke due to carotid artery disease.
• A nephrologist. This is a doctor who specializes in diagnosing and treating kidney diseases and conditions. You may go to a nephrologist if you have chronic kidney disease.

Physical Exam

During the physical exam, your doctor may listen to your arteries for an abnormal whooshing sound called a bruit. Your doctor can hear a bruit when placing a stethoscope over an affected artery. A bruit may indicate poor blood flow due to plaque buildup.

Your doctor also may check to see whether any of your pulses (for example, in the leg or foot) are weak or absent. A weak or absent pulse can be a sign of a blocked artery.

Diagnostic Tests

Your doctor may recommend one or more tests to diagnose atherosclerosis. These tests also can help your doctor learn the extent of your disease and plan the best treatment.

Blood Tests

Blood tests check the levels of certain fats, cholesterol, sugar, and proteins in your blood. Abnormal levels may be a sign that you're at risk for atherosclerosis.

EKG (Electrocardiogram)

An EKG is a simple, painless test that detects and records the heart's electrical activity. The test shows how fast the heart is beating and its rhythm (steady or irregular). An EKG also records the strength and timing of electrical signals as they pass through the heart.

An EKG can show signs of heart damage caused by CHD. The test also can show signs of a previous or current heart attack.

Chest X Ray

A chest x ray takes pictures of the organs and structures inside your chest, such as your heart, lungs, and blood vessels. A chest x ray can reveal signs of heart failure.

Ankle/Brachial Index

This test compares the blood pressure in your ankle with the blood pressure in your arm to see how well your blood is flowing. This test can help diagnose P.A.D.

Echocardiography

Echocardiography (echo) uses sound waves to create a moving picture of your heart. The test provides information about the size and shape of your heart and how well your heart chambers and valves are working.

Echo also can identify areas of poor blood flow to the heart, areas of heart muscle that aren't contracting normally, and previous injury to the heart muscle caused by poor blood flow.

Computed Tomography Scan

A computed tomography (CT) scan creates computer-generated pictures of the heart, brain, or other areas of the body. The test can show hardening and narrowing of large arteries.

A cardiac CT scan also can show whether calcium has built up in the walls of the coronary (heart) arteries. This may be an early sign of CHD.

Stress Testing

During stress testing, you exercise to make your heart work hard and beat fast while heart tests are done. If you can't exercise, you may be given medicine to make your heart work hard and beat fast.

When your heart is working hard, it needs more blood and oxygen. Plaque-narrowed arteries can't supply enough oxygen-rich blood to meet your heart's needs.

A stress test can show possible signs and symptoms of CHD, such as:

• Abnormal changes in your heart rate or blood pressure
• Shortness of breath or chest pain
• Abnormal changes in your heart rhythm or your heart's electrical activity

As part of some stress tests, pictures are taken of your heart while you exercise and while you rest. These imaging stress tests can show how well blood is flowing in various parts of your heart. They also can show how well your heart pumps blood when it beats.

Angiography

Angiography is a test that uses dye and special x rays to show the inside of your arteries. This test can show whether plaque is blocking your arteries and how severe the blockage is.

A thin, flexible tube called a catheter is put into a blood vessel in your arm, groin (upper thigh), or neck. Dye that can be seen on an x-ray picture is injected through the catheter into the arteries. By looking at the x-ray picture, your doctor can see the flow of blood through your arteries.

Other Tests

Other tests are being studied to see whether they can give a better view of plaque buildup in the arteries. Examples of these tests include magnetic resonance imaging (MRI) and positron emission tomography (PET).

How Is Atherosclerosis Treated?

Treatments for atherosclerosis may include lifestyle changes, medicines, and medical procedures or surgery.

The goals of treatment include:

• Relieving symptoms
• Reducing risk factors in an effort to slow or stop the buildup of plaque
• Lowering the risk of blood clots forming
• Widening or bypassing plaque-clogged arteries
• Preventing atherosclerosis-related diseases

Lifestyle Changes

Making lifestyle changes often can help prevent or treat atherosclerosis. For some people, these changes may be the only treatment needed.

Follow a Healthy Diet

A healthy diet is an important part of a healthy lifestyle. Following a healthy diet can prevent or reduce high blood pressure and high blood cholesterol and help you maintain a healthy weight.

For information about healthy eating, go to the National Heart, Lung, and Blood Institute's (NHLBI's) Aim for a Healthy Weight Web site. This site provides practical tips on healthy eating, physical activity, and weight control.

Therapeutic Lifestyle Changes (TLC). 

Your doctor may recommend TLC if you have high blood cholesterol. TLC is a three-part program that includes a healthy diet, physical activity, and weight management.

With the TLC diet, less than 7 percent of your daily calories should come from saturated fat. This kind of fat is found in some meats, dairy products, chocolate, baked goods, and deep-fried and processed foods.

No more than 25 to 35 percent of your daily calories should come from all fats, including saturated, trans, monounsaturated, and polyunsaturated fats.

You also should have less than 200 mg a day of cholesterol. The amounts of cholesterol and the types of fat in prepared foods can be found on the foods' Nutrition Facts labels.

Foods high in soluble fiber also are part of a healthy diet. They help prevent the digestive tract from absorbing cholesterol. These foods include:

• Whole-grain cereals such as oatmeal and oat bran
• Fruits such as apples, bananas, oranges, pears, and prunes
• Legumes such as kidney beans, lentils, chick peas, black-eyed peas, and lima beans

A diet rich in fruits and vegetables can increase important cholesterol-lowering compounds in your diet. These compounds, called plant stanols or sterols, work like soluble fiber.

A healthy diet also includes some types of fish, such as salmon, tuna (canned or fresh), and mackerel. These fish are a good source of omega-3 fatty acids. These acids may help protect the heart from blood clots and inflammation and reduce the risk for heart attack. Try to have about two fish meals every week.

You should try to limit the amount of sodium (salt) that you eat. This means choosing low-salt and "no added salt" foods and seasonings at the table or while cooking. The Nutrition Facts label on food packaging shows the amount of sodium in the item.

Try to limit drinks with alcohol. Too much alcohol will raise your blood pressure and triglyceride level. (Triglycerides are a type of fat found in the blood.) Alcohol also adds extra calories, which will cause weight gain.

Men should have no more than two drinks containing alcohol a day. Women should have no more than one drink containing alcohol a day. One drink is a glass of wine, beer, or a small amount of hard liquor.

Dietary Approaches to Stop Hypertension (DASH). 

Your doctor may recommend the DASH eating plan if you have high blood pressure. The DASH eating plan focuses on fruits, vegetables, whole grains, and other foods that are heart healthy and low in fat, cholesterol, and salt.

DASH also focuses on fat-free or low-fat milk and dairy products, fish, poultry, and nuts. The DASH eating plan is reduced in red meats (including lean red meats), sweets, added sugars, and sugar-containing beverages. The plan is rich in nutrients, protein, and fiber.

The DASH eating plan is a good heart healthy eating plan, even for those who don't have high blood pressure.

Be Physically Active

Regular physical activity can lower many atherosclerosis risk factors, including LDL ("bad") cholesterol, high blood pressure, and excess weight.

Physical activity also can lower your risk for diabetes and raise your HDL cholesterol level. HDL is the "good" cholesterol that helps prevent atherosclerosis.

Talk with your doctor before you start a new exercise plan. Ask him or her how much and what kinds of physical activity are safe for you.

People gain health benefits from as little as 60 minutes of moderate-intensity aerobic activity per week. For major health benefits, do at least 150 minutes (2 hours and 30 minutes) of moderate-intensity aerobic activity or 75 minutes (1 hour and 15 minutes) of vigorous-intensity aerobic activity each week. The more active you are, the more you will benefit.

Maintain a Healthy Weight

Maintaining a healthy weight can lower your risk for atherosclerosis. A general goal to aim for is a body mass index (BMI) of less than 25.

BMI measures your weight in relation to your height and gives an estimate of your total body fat. You can use the NHLBI's online BMI calculator to figure out your BMI, or your doctor can help you.

A BMI between 25 and 29.9 is considered overweight. A BMI of 30 or more is considered obese. A BMI of less than 25 is the goal for preventing and treating atherosclerosis. Your doctor or health care provider can help you set an appropriate BMI goal.

Quit Smoking

If you smoke or use tobacco, quit. Smoking can damage and tighten blood vessels and raise your risk for atherosclerosis. Talk with your doctor about programs and products that can help you quit. Also, try to avoid secondhand smoke.

If you have trouble quitting smoking on your own, consider joining a support group. Many hospitals, workplaces, and community groups offer classes to help people quit smoking.

Manage Stress

Research shows that the most commonly reported "trigger" for a heart attack is an emotionally upsetting event—particularly one involving anger. Also, some of the ways people cope with stress—such as drinking, smoking, or overeating—aren't healthy.

Learning how to manage stress, relax, and cope with problems can improve your emotional and physical health. Having supportive people in your life with whom you can share your feelings or concerns can help relieve stress.

Physical activity, medicine, and relaxation therapy also can help relieve stress. You may want to consider taking part in a stress management program.

Medicines

To slow the progress of plaque buildup, your doctor may prescribe medicines to help lower your cholesterol level or blood pressure. He or she also may prescribe medicines to prevent blood clots from forming.

For successful treatment, take all medicines as your doctor prescribes.

Medical Procedures and Surgery

If you have severe atherosclerosis, your doctor may recommend a medical procedure or surgery.

Angioplasty is a procedure that's used to open blocked or narrowed coronary (heart) arteries. Angioplasty can improve blood flow to the heart and relieve chest pain. Sometimes a small mesh tube called a stent is placed in the artery to keep it open after the procedure.

Coronary artery bypass grafting (CABG) is a type of surgery. In CABG, arteries or veins from other areas in your body are used to bypass (that is, go around) your narrowed coronary arteries. CABG can improve blood flow to your heart, relieve chest pain, and possibly prevent a heart attack.

Bypass grafting also can be used for leg arteries. For this surgery, a healthy blood vessel is used to bypass a narrowed or blocked artery in one of the legs. The healthy blood vessel redirects blood around the blocked artery, improving blood flow to the leg.

Carotid endarterectomy  is surgery to remove plaque buildup from the carotid arteries in the neck. This procedure restores blood flow to the brain, which can help prevent a stroke.

How Can Atherosclerosis Be Prevented or Delayed?

Taking action to control your risk factors can help prevent or delay atherosclerosis and its related diseases. Your risk for atherosclerosis increases with the number of risk factors you have.

One step you can take is to adopt a healthy lifestyle. Following a healthy diet is an important part of a healthy lifestyle.

A healthy diet includes a variety of fruits and vegetables (including beans and peas). It also includes whole grains, lean meats, poultry without skin, seafood, and fat-free or low-fat milk and dairy products. A healthy diet is low in sodium (salt), added sugar, solid fats, and refined grains.

The National Heart, Lung, and Blood Institute's (NHLBI's) Therapeutic Lifestyle Changes (TLC) and Dietary Approaches to Stop Hypertension (DASH) are two programs that promote healthy eating.

If you're overweight or obese, work with your doctor to create a reasonable weight-loss plan. Controlling your weight helps you control atherosclerosis risk factors.

Be as physically active as you can. Physical activity can improve your fitness level and your health. Ask your doctor what types and amounts of activity are safe for you.

If you smoke, quit. Smoking can damage and tighten blood vessels and raise your risk for atherosclerosis. Talk with your doctor about programs and products that can help you quit. Also, try to avoid secondhand smoke.

Know your family history of atherosclerosis. If you or someone in your family has an atherosclerosis-related disease, be sure to tell your doctor.

If lifestyle changes aren't enough, your doctor may prescribe medicines to control your atherosclerosis risk factors. Take all of your medicines as your doctor advises.

Living With Atherosclerosis

Improved treatments have reduced the number of deaths from atherosclerosis-related diseases. These treatments also have improved the quality of life for people who have these diseases.

Adopting a healthy lifestyle may help you prevent or delay atherosclerosis and the problems it can cause. This, along with ongoing medical care, can help you avoid the problems of atherosclerosis and live a long, healthy life.

Researchers continue to look for ways to improve the health of people who have atherosclerosis or may develop it.

Ongoing Care

If you have atherosclerosis, work closely with your doctor and other health care providers to avoid serious problems, such as heart attack and stroke.

Follow your treatment plan and take all of your medicines as your doctor prescribes. Your doctor will let you know how often you should schedule office visits or blood tests. Be sure to let your doctor know if you have new or worsening symptoms.

Emotional Issues and Support

Having an atherosclerosis-related disease may cause fear, anxiety, depression, and stress. Talk about how you feel with your doctor. Talking to a professional counselor also can help. If you're very depressed, your doctor may recommend medicines or other treatments that can improve your quality of life.

Community resources are available to help you learn more about atherosclerosis. Contact your local public health departments, hospitals, and local chapters of national health organizations to learn more about available resources in your area.

Talk about your lifestyle changes with your family and friends—whoever can provide support or needs to understand why you're changing your habits.

Family and friends may be able to help you make lifestyle changes. For example, they can help you plan healthier meals. Because atherosclerosis tends to run in families, your lifestyle changes may help many of your family members too.

Reference: National Heart Lung and Blood Institute. http://www.nhlbi.nih.gov/health/health-topics/topics/atherosclerosis/