Atherosclerosis

Diseases caused by atherosclerosis are the leading cause of illness and death for both men and women in the U.S, according to the National Heart, Lung, and Blood Institute. Although breast cancer is often the illness most feared by women, the disease affects one out of nine women over the lifetime, compared to coronary heart disease, which affects one out of every two women over the lifetime. Atherosclerosis is often the first stage of coronary heart disease (CHD).

Often referred to as "hardening of the arteries," atherosclerosis occurs when your arteries narrow and become less flexible. This happens when cholesterol, fatty substances, cell waste products, calcium and fibrin—collectively called plaque—collect on the inner walls. The arteries respond to the buildup by becoming inflamed, which, in turn, results in the formation of scar tissue and the collection of other cells in the affected areas, further narrowing the artery.

Atherosclerosis can affect medium and large arteries anywhere in your body. If someone has atherosclerosis in one part of their body, they typically will also have atherosclerosis in other parts of their bodies. Atherosclerosis restricts blood flow, thus limiting the amount of oxygen available to your organs. When blood flow to the heart is reduced, for instance, chest pain, or angina, may result. Similarly, when blood flow to the arteries in the legs are reduced, leg pain called claudication may result.

As the disease progresses, atherosclerosis can completely clog arteries, cutting off blood flow. This usually happens suddenly when a blood clot forms in the damaged arteries on top of the atherosclerosis. This is especially dangerous in arteries near the brain, heart or other vital organs. If blood flow to the heart is nearly or completely blocked, a heart attack results and muscle cells in the heart die. The result is permanent heart damage. Similarly, if blood flow is abruptly cut off to the brain, this can cause a stroke, which may also result in permanent brain damage. And if blood flow is abruptly cut off to the legs, the leg may have to be amputated. Thus atherosclerosis can lead to serious life-threatening complications if not addressed early through prevention and early treatment.

Atherosclerotic plaques have a cholesterol- or lipid-rich core covered by a fibrous cap. If this cap ruptures, it exposes this lipid-rich core to blood. The sticky core attracts platelets, forming a blood clot, called a thrombus, at the site. This clot can completely clog the artery and cut off blood flow.

More mature plaques (stable plaques) have a thick fibrous cap, which is less likely to rupture. Softer, fattier plaques (unstable plaques) have a weaker cap and are more likely to rupture.

Two thirds of sudden total or near total blockage (called an occlusion) develops in arteries that were less than 50 percent narrowed, and 97 percent of plaque rupture occurs in arteries with less than 70 percent narrowing.

So the degree of narrowing in a particular artery does not necessarily predict complete blockage in that same artery.

Tighter or narrower arteries may cause angina, but are not necessarily more likely to rupture. However, the total amount of plaque or atherosclerosis in all your arteries predicts your risk of a heart attack.

We don't know what causes plaque to begin building up in arteries. Some experts think plaque begins to accumulate in places where the inner layer of an artery is damaged.

The specific arteries most at risk for atherosclerosis-induced blockage are those going to your brain (carotid), heart (coronary) and legs (femoral or iliac). Atherosclerosis in the legs is the most common form of peripheral arterial disease (PAD) and can lead to intermittent claudication—severe pain, aching or cramping when walking, numbness, reduced circulation, and if left untreated, gangrene (death of tissue).

While atherosclerosis is typically a disease that progresses gradually—sometimes even starting in childhood—you are most at risk when arterial blockage builds up quickly, completely closing off an entire artery. This can happen if the plaque ruptures.

Risk Factors for Atherosclerosis:Over the last two decades, researchers have identified many risk factors for developing cardiovascular diseases. They include:

Elevated cholesterol levels (both total cholesterol and LDL ("bad") cholesterol)

Elevated triglyceride levels

High blood pressure hypertension

Cigarette smoke

Low HDL cholesterol (the "good" cholesterol that clears away artery-clogging LDL cholesterol—the "bad" cholesterol)

Diabetes (elevated blood sugar)

Advanced age

High cholesterolMore than half of women over age 55 need to lower their blood cholesterol, and a quarter of all American women have blood cholesterol levels high enough to pose a serious risk for coronary heart disease-a result of atherosclerosis.

Cholesterol begins collecting in the walls of the arteries at an early age. In fact, the earliest type of arterial lesion, the "fatty streak," is present even in young children.

According to the National Cholesterol Education Program (NCEP), elevated LDL cholesterol is a major cause of coronary heart disease. That's why the NCEP panel recommends aggressive treatment. Treatment may include lifestyle changes, such as exercising more and reducing the amount of saturated fat in your diet, and medication. A combination of approaches is typically recommended.

Other lipid abnormalities, such as elevated triglycerides or low HDL (the good cholesterol), are also associated with increased cardiovascular risk.

Cigarette smokingSmoking accelerates the development of atherosclerosis, increases blood pressure and restricts the amount of oxygen the blood supplies to the body. Quitting smoking dramatically and immediately lowers the risk of a heart attack and also reduces the risk of a second heart attack in people who have already had one.

DiabetesHaving diabetes poses as great a risk for having a heart attack in 10 years as heart disease itself, according to NHLBI. In fact, cardiovascular disease is the leading cause of diabetes-related deaths. People with diabetes who have not yet had a heart attack have the same risk of future heart attack as someone with known coronary heart disease. Because their risk of heart attack is so high, NHLBI recommends that people with diabetes be treated aggressively with LDL cholesterol lowering medication and carefully manage their blood sugar to reduce their cardiovascular risk.

AgeGenerally, women over age 55 and men over age 45 are at greatest risk for developing atherosclerosis. The risk of cardiovascular events increases with age.

Global Risk Factor AssessmentThe Framingham Risk Score is a useful, office-based risk prediction model. It assigns a point score for each major risk factor to predict your 10-year risk of developing future cardiovascular events. You can estimate your own 10-year risk at: http://hp2010.nhlbihin.net

If you have more than a 20 percent risk of future cardiac events over the next 10 years, you should be treated very aggressively, the same as someone with known heart disease. Intermediate risk individuals with scores between 10 percent and 20 percent should have further risk evaluation. Low-risk individuals with scores of less than 10 percent usually don't need drug therapy, but should make lifestyle changes such as diet and exercise, which are recommended for everyone.

Other risk factors for coronary heart disease include:A family history of early heart disease

Obesity

Metabolic syndrome

Physical inactivity and sedentary lifestyle

Postmenopausal status

High levels of homocysteine

Family HistoryEven though it is not included in the Framingham Risk Score, family history is one of the biggest risk factors overall for atherosclerosis. Your risk is greater if your father or brother was diagnosed before age 55, if your mother or sister was diagnosed before age 65, or if you have a sibling with early coronary disease.

ObesityOverweight women are much more likely to develop heart-related problems, even if they have no other risk factors. Excess body weight in women is linked with coronary heart disease, stroke, congestive heart failure and death from heart-related causes.

InactivityNot exercising contributes directly to heart-related problems and increases the likelihood that you'll develop other risk factors, such as high blood pressure and diabetes.

Metabolic SyndromeThis deadly quartet of abdominal obesity, high blood pressure, glucose intolerance (or pre-diabetes) and abnormal cholesterol is associated with a markedly increased risk of cardiovascular disease.

HomocysteineHomocysteine is an amino acid normally found in the body. Studies suggest that high blood levels of this substance may increase the risk of heart disease, stroke and peripheral vascular disease.

StressAlthough stress has been implicated in the development of atherosclerosis, its exact relationship to heart disease has not been determined. Regular exercise can reduce stress and improve your mood.

Post-menopausal statusA woman's risk of developing atherosclerosis and heart disease increases once she reaches menopause. Prior to menopause, women are mainly protected from heart disease by estrogen, the reproductive hormone produced by the ovaries. This protection is why women tend to develop heart disease 10 years after men. However this 10-year protection is not seen in women who smoke or those with diabetes.

Among its many roles, estrogen helps keep arteries free from plaque by improving the ratio of LDL (low-density lipoprotein) and HDL (high-density lipoprotein) cholesterol. It also increases the amount of HDL cholesterol, which helps clear arteries of LDL cholesterol—the kind that most contributes to plaque build up.

Estrogen also helps keep the lining of your blood vessels strong and pliable, which helps reduce your risk of atherosclerosis. Despite the theoretical benefits of estrogen, replacing natural estrogen hormones with drugs after menopause is not an effective way to prevent heart disease, and may even be harmful.

Symptoms of Atherosclerosis:Often, you will experience no symptoms of atherosclerosis until the disease has progressed significantly. However, there are some conditions that may suggest atherosclerosis is present, although these conditions may also happen for other reasons.

Angina. If clogged arteries prevent enough oxygen-carrying blood from reaching your heart, the heart may respond with pain called angina pectoris. Episodes of angina occur when the heart's need for oxygen increases beyond the oxygen available from the blood nourishing the heart. Silent angina occurs when the same inadequate blood supply causes no symptoms.

Physical exertion is the most common trigger for angina. Other triggers can be emotional stress, extreme cold or heat, heavy meals, alcohol and cigarette smoking. The pain is a pressing or squeezing pain, usually felt in the chest or sometimes in the shoulders, arms, neck, jaws or back.

Angina suggests that coronary heart disease exists. People with angina have an increased risk of heart attack compared with those who have no symptoms. When the pattern of angina changes—if episodes become more frequent, last longer or occur without exercise—your risk of heart attack in subsequent days or weeks is much higher and you should see your health care professional immediately.

If you have angina, learn its pattern—what causes an angina attack, what it feels like, how long episodes usually last and whether medication relieves the attack. Angina is usually relieved in a few minutes by resting or taking prescribed angina medicine, such as nitroglycerin.

Episodes of angina seldom cause permanent damage to heart muscle.

Heart attack pain may be similar to angina, but the symptoms of angina quickly disappear with rest. Heart attack pain, however, usually persists despite resting or taking nitroglycerin and should be evaluated immediately. Like angina, heart attack pain can be a pressure or tightness in chest, arms, back or neck. Often symptoms include shortness of breath, sweating, nausea, vomiting, indigestion or dizziness. Women, especially those with diabetes, may not have the typical symptoms of chest pain like men, but other symptoms such as shortness of breath or indigestion. A heart attack is an emergency. A delay in treatment could mean more of the heart muscle tissue is permanently damaged. If you think you're having a heart attack, take an aspirin (which reduces blood clotting) and get medical help immediately.

Cardiac arrhythmias. These occur when the heart momentarily beats too fast or beats irregularly. Chest pain, dizziness and shortness of breath are symptoms of cardiac arrhythmias. Atherosclerosis is one cause of rapid or irregular heartbeat; however, it can also be caused by angina, valvular heart disease, blood clots, thyroid abnormalities, electrolyte imbalance or previous heart damage. Arrhythmias may be frequent or infrequent.

Silent ischemia. Sometimes atherosclerosis causes no symptoms. Silent ischemia is a condition caused by atherosclerosis, but isn't associated with the chest pain or other symptoms common to other types of heart conditions. This condition occurs when arteries with atherosclerosis can't deliver enough blood to the heart. An electrocardiogram (EKG or ECG), a measurement of electrical impulses produced by the heart, may indicate silent ischemia. However, unless you know your risks for heart disease and decide, with the advice of your health care professional, that you need a heart checkup, you may never know you have ischemia. People with diabetes are especially at risk for this condition.

Intermittent claudication. This leg disorder predominantly affects elderly people. It causes severe pain, aching or cramping in the legs when you walk due to atherosclerosis in the major arteries that supply blood to the legs (femoral and iliac). Severe cases of peripheral arterial disease can lead to gangrene and amputation.

Transient ischemic attack (TIA). If you experience a sudden onset of weakness or numbness on one side of your face, arm, or leg, or an inability to talk or find words, or lose vision in one eye, you may be having a mini-stroke or TIA. Neurological symptoms that last less than 24 hours are called TIAs, where as symptoms that persist for longer periods are classified as strokes.

They are often the result of atherosclerosis in the arteries that supply blood to the brain, such as the carotid arteries. This is very serious. If you experience these symptoms, seek medical attention immediately. This is the brain's equivalent of a "heart attack," during which the brain is deprived of oxygen-carrying blood supply. Any delay in medical treatment may permanently damage your brain.