Coronary Artery Disease

Coronary artery disease (CAD) is a specific form of atherosclerosis, a disease characterized by the buildup of deposits, or plaques, in the blood vessels. The term atherosclerosis comes from two Greek words, athero, meaning “gruel” or “paste,” and sclerosis, meaning “hardness.”

Atherosclerotic plaques consist of both fatty substances called lipids, and also “harder” substances, such as calcium and fibrous tissue. Over time, plaques in the blood vessels can interfere with the supply of blood to various organs of the body. Conditions caused by atherosclerosis include:

• Coronary artery disease. This is when the coronary arteries, which feed the heart muscle, are affected. As the blood flow to the heart muscle is restricted, angina (chest pains) or heart attack can occur.

• Stroke. If atherosclerosis affects the blood vessels feeding the brain, the blood supply to a portion of the brain may be restricted or cut off. The result is a stroke.

• Aneurysm. Atherosclerosis can lead to an aneurysm—a fluid- and blood-filled sac in the wall of an artery or vein. If an aneurysm ruptures, the result is internal bleeding and lack of adequate blood supply where it is needed.

• Claudication. When atherosclerosis develops in the blood vessels going to the legs, it can result in leg pain during exercise, also called claudication. People with atherosclerotic disease in one blood vessel are more likely to develop it in others as well. Just like high blood pressure or diabetes, atherosclerotic diseases such as CAD require lifelong treatment. With proper treatment, most patients are now living long, active lives, and the outlook for those with the disease is getting better every year.

Causes

Atherosclerosis begins early in adulthood, but it may be decades before it becomes obvious. Very early plaques have been found in young soldiers killed in battle. Atherosclerosis probably begins when the innermost layer of the artery, called the endothelium, becomes damaged, allowing cholesterol to enter. Causes of damage to the arterial wall include:

• Elevated levels of cholesterol and triglycerides (fats) in the blood

• High blood pressure

• Tobacco smoke Once the endothelium is damaged, fats, cholesterol, fibrin, platelets, cellular debris, calcium, and other substances can catch on the damaged spot and over time become deposited in the artery wall, stimulating the development of plaques. In some instances, atherosclerosis may weaken the blood vessel wall, causing the vessel to become wider, rather than narrower.

Although the dangers of narrowed blood vessels are well known, widening can also be a serious problem. It can develop into an aneurysm. This often occurs in the aorta (the main artery in the heart), but it can also occur in the coronary arteries. A blood vessel can also widen at the same spot where a plaque forms. If this occurs, the inside diameter of the blood vessel may change only slightly, despite the presence of the plaque. This explains why some people can have a fairly normal stress test or angiogram but can still have coronary artery disease and even heart attacks.

The problem with plaque

Plaques contain a number of different substances. The most important are the fatty substances or lipids—the athero, or “gruel” part of the word atherosclerosis. The other contents—muscle cells, fibrous tissue, and calcium—are the sclerosis part. Most heart attacks occur because an atherosclerotic plaque has become unstable.

Unstable plaque

Unstable plaques contain large amounts of lipids covered by a thin coating called a fibrous cap. Inflammatory cells in the plaque may eat away this fibrous cap, causing the contents of the plaque to spill out into the bloodstream. There they interact with blood elements and clotting factors to cause a blood clot. If the clot is large enough to completely obstruct blood flow through a coronary artery, a heart attack occurs.

Narrowing plaque

Plaque may narrow the blood vessel enough to limit blood flow through the vessel. This usually causes symptoms only during exercise or stress. The likelihood that a plaque will rupture and cause a heart attack is not related to the severity of the narrowing. A plaque that narrows a vessel by only 30 percent may cause a heart attack, while a larger one that narrows a blood vessel by 90 percent may remain stable for years, perhaps causing chest pain during exercise but not resulting in a heart attack. The chance of a plaque erupting is related to its stability, not its size.

Risk factors

Scientists continue to investigate the possible causes of coronary artery disease. Although there does not seem to be one specific cause, there are certain characteristics that have been linked to coronary artery disease and heart attacks. These are called risk factors.

Risk factors beyond your control

Although you can do much to lower your risk for CAD, some factors you can’t control. These include age, gender, and a family history of heart disease:

• Age. Men 45 years or older or women 55 years or older are at greater risk for CAD.

• Gender. Middle-aged men have more heart attacks than women of the same age. This changes after menopause. After age 60, when a woman’s estrogen level decreases, the rates are almost equal between both sexes.

• Family history of heart disease. If your mother, father, or sibling was diagnosed with coronary artery disease before age 60, you have increased risk.

Risk factors that can be changed

There are some risk factors you can control. By reducing your risks, you are taking steps to live healthier and lessen your chances of developing heart disease

• Tobacco use. Tobacco use lowers your level of good cholesterol, raises your blood pressure, and promotes clotting.

•  High blood cholesterol and high triglycerides. Most heart disease is the result of cholesterol-rich, fatty buildup that narrows the vessels that supply blood to your heart. There are two sources of cholesterol: (1) your body, which makes cholesterol to aid digestion, and (2) the foods you eat.

• Low-density lipoprotein cholesterol (LDL, or “bad cholesterol”) accounts for most of the cholesterol in your blood and is considered most responsible for the formation of plaque. Most people with CAD require medication to achieve target LDL levels.

• High-density lipoprotein cholesterol (HDL, or “good cholesterol”). Higher levels of HDL protect against CAD.

• Triglycerides are fats that are carried in the bloodstream. When triglycerides are elevated, the risk for CAD increases.

• High blood pressure. High blood pressure damages arteries, setting the stage for plaque formation. It also increases the stress on the heart muscle, which may cause damage to the organ.

• Lack of exercise. People who have had heart attacks may increase their chances of survival if they change their habits to include regular physical activity. Exercise can help control blood fats and blood glucose, maintain weight, and lower blood pressure.

• Diabetes. People with diabetes are very susceptible to CAD. It is especially important for people with diabetes to control their blood glucose, as well as blood pressure and cholesterol.

• How you handle stress. Stress is a normal part of everyone’s life. It is not stress that increases your risk for CAD, but how you cope with it.

• Excess weight or obesity. By itself, obesity increases your risk for CAD. Obesity also contributes to other risk factors, including hypertension, high blood cholesterol, and diabetes.

Symptoms

Angina

Angina is one of the noticeable signs of coronary artery disease. It is a warning sign that the heart is temporarily not getting enough blood and oxygen to handle its workload. Angina does not cause permanent damage to the heart muscle. Angina can feel like a heart attack, but it is different. Most angina attacks last from 2 to 15 minutes. This is because the blood supply is reduced but not cut off. The warning signs of angina include:

Feeling of indigestion or “fullness” • Discomfort, aching, pressure, tightness, heaviness, or burning sensation in or near the chest, back, arms, shoulders, between shoulder blades, neck, throat, or jaw Anything that elevates blood pressure or heart rate can result in angina:

• Smoking

• Physical activity

• Heavy meals

• Hot or iced drinks

• Hot baths and saunas

• Emotional stress

•  Exposure to extreme temperatures Angina is usually treated with rest and a medication called nitroglycerin. The discomfort usually is gone within 15 minutes.

Treatment

 Many people who have coronary artery disease do not realize that it is a chronic condition that cannot be cured. The good news is it can be treated and stabilized. Lifestyle changes can help treat CAD. Your doctor may ask you to do any of the following:

• Eat a diet low in fat and cholesterol.

• Be more active.

• If you use tobacco, quit.

• Lose 10 to 20 pounds.

Many people do not realize that procedures such as balloon angioplasty, stents, and even bypass surgery do not decrease the chance of death or heart attacks. These therapies are effective in reducing symptoms of chest pain and improving quality of life. The treatments that have the best track record in prolonging life are medications, such as aspirin, cholesterol-lowering drugs (statins), beta-blockers. Angiotensin- converting enzyme (ACE) inhibitors and angiotensin-receptor blockers (ARBs) are also included among the most successful medications. In part, these medications are so successful because they provide protection 24 hours a day, 7 days a week.

Prevention

You can take steps to decrease your risk of coronary artery disease by making some lifestyle changes:

• Check your blood cholesterol and triglycerides. All adults 20 years of age and older should have their cholesterol checked every 5 years.

• Stop smoking. This is the single most important lifestyle change to improve your overall health. Check into community resources such as the American Lung Association and the American Cancer Society for and support groups for help. Your doctor or employer may also be able to give you suggestions on methods to stop smoking.

• Eat a healthy diet. Eat a variety of fruits, vegetables, and low-fat whole grains. Be careful about how much animal fat you eat—limit your intake of meat and high-fat dairy products such as cheese and ice cream.

• Be active. Find ways to be active at least 30–60 minutes every day. Take the stairs instead of the elevator, avoid sitting for longer than 30 minutes at a time, and try a variety of activities to keep exercise interesting. 

• Lose or maintain weight. If you are overweight, losing just 10 to 20 pounds can have health benefits. If you are not overweight, take steps to prevent weight gain as you get older.