Heart attack

Definition

A heart attack is the death of, or damage to, part of the heart muscle because its blood supply is severely reduced or stopped.

Description

Heart attack is the leading cause of death in the United States. Approximately every 29 seconds one American will have a heart attack, and once a minute one American will die from a heart attack. More than 1.5 million Americans suffer a heart attack every year, and almost half a million die, according to the American Heart Association. Most heart attacks are the end result of years of silent but progressive coronary artery disease, which can be prevented in many people. A heart attack is often the first symptom of coronary artery disease. According to the American Heart Association, 63% of women and 48% of men who died suddenly of coronary artery disease had no previous symptoms. Heart attacks are also called myocardial infarctions (MIs).

A heart attack occurs when one or more of the coronary arteries that supply blood to the heart are completely blocked and blood to the heart muscle is cut off. The blockage is usually caused by atherosclerosis , the buildup of plaque in the artery walls, and/or by a blood clot in a coronary artery. Sometimes, a healthy or atherosclerotic coronary artery has a spasm and the blood flow to part of the heart decreases or stops. Why this happens is unclear, but it can result in a heart attack.

About half of all heart attack victims wait at least two hours before seeking help. This increases their chance of sudden death or being disabled. The longer the artery remains blocked during a heart attack, the more damage will be done to the heart. That is why it is important to recognize the signs of a heart attack and seek prompt medical attention at the nearest hospital with 24-hour emergency cardiac care.

About one fifth of all heart attacks are silent, that is, the victim does not know one has occurred. Although the victim feels no pain , silent heart attacks can still damage the heart.

The outcome of a heart attack also depends on where the blockage is, whether the heart rhythm is disturbed, and whether another coronary artery supplies blood to that part of the heart. Blockages in the left coronary artery are usually more serious than in the right coronary artery. Blockages that cause an arrhythmia, an irregular heartbeat, can cause sudden death.

Causes & symptoms

Heart attacks are generally caused by severe coronary artery disease. Most heart attacks are caused by blood clots that form on atherosclerotic plaque. This blocks a coronary artery from supplying oxygen-rich blood to part of the heart. A number of factors increase the risk of developing coronary artery disease.

Major risk factors significantly increase the risk of coronary artery disease. Those that cannot be changed are:

• Heredity. People whose parents have coronary artery disease are more likely to develop it as well. African Americans are also at increased risk, due to their higher rate of severe hypertension than whites.
• Gender. Men under the age of 60 years of age are more likely to have heart attacks than women of the same age.
• Age. Men over the age of 45 and women over the age of 55 are considered at risk. Older people (those over 65) are more likely to die of a heart attack. Older women are twice as likely to die within a few weeks of a heart attack than men. This may be because of other co-existing medical problems.

Major risk factors that can be changed are:

• Smoking . Smoking greatly increases both the chance of developing coronary artery disease and the change of dying from it. Smokers have two to four times the risk of non-smokers of sudden cardiac death and are more than twice as likely to have a heart attack. They are also more likely to die within an hour of a heart attack.
• High cholesterol . Cholesterol is a soft, waxy substance that is produced by the body, as well as obtained from eating foods such as meat, eggs, and other animal products. Cholesterol level is affected by age, sex, heredity, and diet. Risk of developing coronary artery disease increases as blood cholesterol levels increase. Total cholesterol of 240 mg/dL and over poses a high risk, and 200–239 mg/dL a borderline high risk. In LDL cholesterol, high risk starts at 130–159 mg/dL, depending on other risk factors. HDL (healthy cholesterol) can lower or raise the coronary risk also.
• High blood pressure. High blood pressure makes the heart work harder, and over time, weakens it. It increases the risk of heart attack, stroke , kidney failure, and congestive heart failure. A blood pressure of 140 over 90 or above is considered high. As the numbers increase, high blood pressure goes from Stage 1 (mild) to Stage 4 (very severe). When combined with obesity , smoking, high cholesterol, or diabetes, the risk of heart attack or stroke increases several times.
• Lack of physical activity. This increases the risk of coronary artery disease. Even modest physical activity is beneficial if done regularly.
• Use of certain drugs or supplements. Extreme caution is advised in the use of the herbal supplement ephedra . The supplement, which was marketed for weight loss and to improve athletic performance, was found to contribute to heart attack, seizure, stoke and death. In April 2003, the U.S. Food and Drug Administration (FDA) investigating controlling or banning the substance. While it was once believed that hormone replacement therapy (HRT) helped prevent heart disease in women, a large clinical trial called the Women's Health Initiative found the opposite to be true. In 2003, the FDA began requiring manufacturers of HRT to place warnings on the box listing adverse effects of estrogen, including increased risk of heart attack, stroke and blood clots. The labels also must mention that HRT should not be used as a preventive medicine for heart disease.

Contributing risk factors

Contributing risk factors have been linked to coronary artery disease, but their significance and prevalence are not known yet. Contributing risk factors are:

• Diabetes mellitus. The risk of developing coronary artery disease is seriously increased for diabetics. More than 80% of diabetics die of some type of heart or blood vessel disease.
• Obesity. Excess weight increases the strain on the heart, increases blood pressure and blood cholesterol, and increases the risk of developing coronary artery disease, even if no other risk factors are present. In fact, new research in 2002 shows that losing weight also reduces inflammation of the arteries in obese women, which is a risk factor equal to that of high cholesterol.
• Stress and anger. Some scientists believe that stress and anger can contribute to the development of coronary artery disease. Stress increases the heart rate and blood pressure, and can injure the lining of the arteries.

More than 60% of heart attack victims experience symptoms before the heart attack occurs. These sometimes occur days or weeks before the heart attack. Sometimes, people do not recognize the symptoms of a heart attack or are in denial that they are having one. Symptoms are:

• Uncomfortable pressure, fullness, squeezing, or pain in the center of the chest. This lasts more than a few minutes, or may go away and return.
• Pain that spreads to the shoulders, neck, or arms.
• Chest discomfort accompanied by lightheadedness, fainting, sweating, nausea , or shortness of breath.

All of these symptoms do not occur with every heart attack. Sometimes, symptoms disappear and then reappear. A person with any of these symptoms should immediately call an emergency rescue service or be driven to the nearest hospital emergency room.

Diagnosis

Experienced emergency care personnel can usually diagnose a heart attack simply by looking at the patient. To confirm this diagnosis, they talk with the patient, check heart rate and blood pressure, perform an electrocardiogram, and take a blood sample. The electrocardiogram shows which coronary artery is blocked. Electrodes covered with conductive jelly are placed on the patient's chest, arms, and legs. They send impulses of the heart's activity through an oscilloscope (a monitor) to a recorder, which traces them on paper. The blood test shows the leak of enzymes or other biochemical markers from damaged cells in the heart muscle. In 2003, the FDA cleared a new test for ruling out heart attacks in people who come to emergency rooms with severe chest pains. It is the first new blood test for evaluation of heart attacks since 1994 and is used along with an electrocardiogram.

Treatment

Heart attacks are treated with cardiopulmonary resuscitation (CPR) when necessary to start and keep the patient breathing and his heart beating. Upon arrival at the hospital, the patient is closely monitored. An electrical-shock device called a defibrillator may be used to restore a normal rhythm if the heartbeat is fluttering uncontrollably. Oxygen is often used to ease the heart's workload or to help a victim of a severe heart attack breathe easier. If oxygen is used within hours of the heart attack, it may help limit damage to the heart.

Alternative therapies aim at preventing the progression of heart disease that leads to a heart attack. Changes in lifestyle can also prevent second heart attacks.

Herbal medicine offers a variety of remedies that may have a beneficial effect on coronary artery disease. Oats (Avena sativa ), garlic (Allium sativum ), and guggul (Commiphora mukul ) may help reduce cholesterol; linden (Tilia europaea ) and hawthorn (Crataegus spp.) are sometimes recommended to control high blood pressure, a risk factor for heart disease. Tea (Camellia sinensis ), especially green tea , is high in antioxidants , which studies have shown may have a preventative effect against atherosclerosis. A 2003 study found that black tea may reduce the risk of a heart attack by as much as 43% and that black tea's protective effects are even greater in women than in men.

Nutritional therapies have been shown to prevent coronary artery disease and stop, or even reverse, the progression of atherosclerosis. A low-fat, high-fiber diet is often recommended. It is essential to reduce the amount of meat and animal products consumed, as they are high in saturated fats. Whole grains, fresh fruits and vegetables, legumes, and nuts are recommended. Vitamin and mineral supplements that reduce, reverse, or protect against coronary artery disease include chromium ; calcium and magnesium ; B complex vitamins; the antioxidant vitamins B and E; L-carnitine; and zinc . These protective effects even work in the elderly, according to a 2003 report. A study revealed that those age 65 and older who ate the most cereal and bread fiber were 21% less likely to develop heart disease than those who ate the least. They also were less likely to have a heart attack or stroke.

Yoga and other bodywork, massage, relaxation therapies, aromatherapy , and music therapy may also help by reducing stress and promoting physical and mental wellbeing. A 1996 study in the United Kingdom found that participants who practiced t'ai chi had a resulting lowering in blood pressure. By evoking the body's relaxation response through meditation and deep breathing, blood pressure, metabolic rate, and hearth rate can all be reduced.

Allopathic treatment

Additional treatment after a heart attack can include close monitoring, electric shock, drug therapy, re-vascularization procedures, percutaneous transluminal coronary angioplasty and coronary artery bypass surgery.

Drugs to stabilize the patient and limit damage to the heart include thrombolytics, aspirin, anticoagulants, painkillers and tranquilizers, beta-blockers, ace-inhibitors, nitrates, rhythm-stabilizing drugs, and diuretics. Thrombolytic drugs that break up blood clots and enable oxygen-rich blood to flow through the blocked artery increase the patient's chance of survival if given as soon as possible after the heart attack. These include anisoylated plasminogen streptokinase activator complex (APSAC) or anistreplase (Eminase), recombinant tissue-type plasminogen activator (r-tPA, Retevase, or Activase), and streptokinase (Streptase, Kabikinase).

To prevent additional heart attacks, aspirin and an anticoagulant drug often follow the thrombolytic drug. These prevent new blood clots from forming and existing blood clots from growing. Anticoagulant drugs help prevent the blood from clotting. The most common anticoagulants are heparin and warfarin. Heparin is given intravenously while the patient is in the hospital; warfarin, taken orally, is often given later. Aspirin helps to prevent the dissolved blood clots from reforming.

To relieve pain, a nitroglycerine tablet taken under the tongue may be given. If the pain continues, morphine sulfate may be prescribed. Tranquilizers such as diazepam (Valium) and alprazolam (Ativan) may be prescribed to lessen the trauma of a heart attack.

Percutaneous transluminal coronary angioplasty and coronary artery bypass surgery are invasive revascularization procedures which open blocked coronary arteries and improve blood flow. They are usually performed only on patients for whom clot-dissolving drugs do not work, or who have poor exercise stress tests, poor left ventricular function, or ischemia . Generally, angioplasty is performed before coronary artery bypass surgery.

Percutaneous transluminal coronary angioplasty, usually called coronary angioplasty, is a non-surgical procedure in which a catheter (a tiny plastic tube) tipped with a balloon is threaded from a blood vessel in the thigh or arm into the blocked artery. The balloon is inflated and compresses the plaque to enlarge the blood vessel and open the blocked artery. The balloon is then deflated and the catheter is removed. Coronary angioplasty is successful about 90% of the time. For one third of patients, the artery narrows again within six months after the procedure. The procedure can be repeated. It is less invasive and less expensive than coronary artery bypass surgery.

In coronary artery bypass surgery, called bypass surgery, a detour is built around the coronary artery blockage with a healthy leg or chest wall artery or vein. The healthy vein then supplies oxygen-rich blood to the heart. Bypass surgery is major surgery appropriate for patients with blockages in two or three major coronary arteries or severely narrowed left main coronary arteries, as well as those who have not responded to other treatments. About 70% of patients who have bypass surgery experience full relief from angina ; about 20% experience partial relief. Long term, symptoms recur in only about three or four percent of patients per year. Five years after bypass surgery, survival expectancy is 90%, at 10 years it is about 80%, at 15 years it is about 55%, and at 20 years it is about 40%.

Expected results

The aftermath of a heart attack is often severe. Twothirds of heart attack patients never recover fully. Within one year, 27% of men and 44% of women die. Within six years, 23% of men and 31% of women have another heart attack, 13% of men and 6% of women experience sudden death, and about 20% have heart failure. People who survive a heart attack have a chance of sudden death that is four to six times greater than others and a chance of illness and death that is two to nine times greater. Older women are more likely than men to die within a few weeks of a heart attack.

New statistics released in early 2002 revealed that about half of all deaths from heart disease happen before the patient can get to the hospital. Women were slightly more likely than men to die quickly after cardiac arrest and the risk of dying quickly from heart disease increased with age, to 61% of those over age 85. The study authors said that improved prevention and recognition of the warning symptoms of heart attack could lower the number of sudden deaths.

Prevention

Many heart attacks can be prevented through a healthy lifestyle, which can reduce the risk of developing coronary artery disease. For patients who have already had a heart attack, a healthy lifestyle and carefully following doctor's orders can prevent another heart attack. A heart healthy lifestyle includes eating right, regular exercise, maintaining a healthy weight, no smoking, moderate drinking, no illegal drugs, controlling hypertension, and managing stress.

A healthy diet includes a variety of foods that are low in fat (especially saturated fat), low in cholesterol, and high in fiber; plenty of fruits and vegetables; and limited sodium . Saturated fat raises cholesterol, and, in excessive amounts, it increases the amount of the proteins in blood that form blood clots. Polyunsaturated and monounsaturated fats are relatively good for the heart.

Fat should comprise no more than 30 percent of total daily calories. In 2002, new evidence suggested that a diet rich in lutein , the pigment found in dark green leafy vegetables, helps artery walls fight plaque and lessens risk of heart attack.

Cholesterol should be limited to about 300 mg per day. Many popular lipid-lowering drugs can reduce LDL-cholesterol by an average of 25–30% when combined with a low-fat, low-cholesterol diet. Soluble fiber can also help lower cholesterol. Fruits and vegetables are rich in fiber, vitamins, and minerals, and they are low calorie and nearly fat free. Vitamin C and beta-carotene, found in many fruits and vegetables, keep LDL-cholesterol from turning into a form that damages coronary arteries. Excess sodium can increase the risk of high blood pressure, and daily intake should be limited to 2,400 mg—about the amount in a teaspoon of salt.

Regular aerobic exercise can lower blood pressure, help control weight, and increase HDL ("good") cholesterol. Moderate intensity aerobic exercise lasting about 30 minutes four or more times per week is recommended for maximum heart health, according to the Centers for Disease Control and Prevention and the American College of Sports Medicine. Three 10-minute exercise periods are also beneficial. Aerobic exercise—activities such as walking, jogging, and cycling—uses the large muscle groups and forces the body to use oxygen more efficiently. It can also include everyday activities such as active gardening, climbing stairs, or brisk housework.

Maintaining a desirable body weight is also important. About one quarter of all Americans are overweight, and nearly one-tenth are obese, according to the Surgeon General's Report on Nutrition and Health. People who are 20% or more over their ideal body weight have an increased risk of developing coronary artery disease. Losing weight can help reduce total and LDL cholesterol, reduce triglycerides, and boost relative levels of HDL cholesterol.

Smoking has many adverse effects on the heart. It increases the heart rate, constricts major arteries, and can create irregular heartbeats. It also raises blood pressure, contributes to the development of plaque, increases the formation of blood clots, and causes blood platelets to cluster and impede blood flow. Heart damage caused by smoking can be repaired by quitting—even heavy smokers can return to heart health. Several studies have shown that ex-smokers face the same risk of heart disease as non-smokers within five to 10 years of quitting.

Drinking should be done in moderation. Modest consumption of alcohol can actually protect against coronary artery disease. This is believed to be because alcohol raises HDL ("good") cholesterol levels in some patients. The American Heart Association defines moderate consumption as one ounce of alcohol per day—roughly one cocktail, one 8-ounce glass of wine, or two 12-ounce glasses of beer. Excessive drinking is always bad for the heart. It usually raises blood pressure, and can poison the heart and cause abnormal heart rhythms or even heart failure. Illegal drugs, like cocaine, can seriously harm the heart and should never be used.

High blood pressure, one of the most common and serious risk factors for coronary artery disease, can be completely controlled through lifestyle changes and medication. People with moderate hypertension may be able to control it through lifestyle changes and medication.

Stress management means controlling mental and physical reactions to life's irritations and challenges. Techniques for controlling stress include thinking positively, getting enough sleep, exercising, and practicing relaxation techniques.

KEY TERMS

Plaque

—A deposit of fatty and other substances that accumulate in the lining of the artery wall.

Daily aspirin therapy has been proven to help prevent blood clots associated with atherosclerosis. It can also prevent heart attacks from recurring, prevent heart attacks from being fatal, and lower the risk of strokes. Surprisingly, a 2002 study found that aspirin therapy is underused by people at risk for heart attacks. Patients should consult their doctors before taking aspirin regularly.

Resources

BOOKS

American Heart Association. 2000 Heart and Stroke Statistical Update. Dallas, TX: American Heart Association, 1999.

DeBakey, Michael E., and Antonio M. Gotto Jr. The New Living Heart. Holbrook, MA: Adams Media Corporation, 1997.

Notelovitz, Morris, and Diana Tonnessen. The Essential Heart Book for Women. New York: St. Martin's Press, 1996.

PERIODICALS

"Aspirin Underused to Prevent Heart Attacks, Strokes." Diabetes Week (January 28, 2002): 15.

Cerrato, Paul L. "Tea Consumption May Benefit Heart and Bone." Contemporary OB/GYN (January 2003):101.

"Drugs or Angioplasty After a Heart Attack?" Harvard Health Letter 22, no. 10 (August 1997): 8.

Evans, Julie, et al. "Popeye's Favorite for Strong-to-the-Finish Arteries." Prevention (January 2002): 108.

"First New Blood Test to Evaluate Heart Attacks." Biomedical Market Newsletter (January-February 2003):42.

"How Weight Loss May Protect Your Heart" Environmental Nutrition (March 2002): 1.

Kirn, Timothy F. "FDA Probes Ephedra, Proposes Warning Label (Risk of Heart Attack, Seizure, Stroke)." Clinical Psychiatry News (April 2003):49.

Marble, Michelle. "FDA Urged to Expand Uses for Aspirin, Benefits for Women." Women's Health Weekly (February 10, 1997).

"More on Anger and Heart Disease." Harvard Heart Letter. (May 1997): 6-7.

Mozaffarian, Dariush, et al. "Cereal, Fruit, and Vegetable Fiber Intake and the Risk of Cardiovascular Disease in Elderly Individuals." JAMA (April 2, 2003):1659.

Stephenson, Joan. "FDA Orders Estrogen Safety Warnings: Agency Offers Guidance for HRT Use." JAMA (February 5, 2003):537.

"Too Many Patients Never Make it to the Hospital Alive" Medical Letter on the CDC & FDA (March 31, 2002): 7.

ORGANIZATIONS

American Heart Association. National Center. 7272 Greenville Avenue, Dallas, TX 75231-4596. (800) AHA-USA1. http://www.americanheart.org

National Heart, Lung, and Blood Institute Information Center. P.O. Box 30105, Bethesda, MD 20824-0105. http://www.nhlbi.gov/nhlbi/nhbli.htm.

Texas Heart Institute Heart Information Service. P.O. Box 20345, Houston, TX 77225-0345. 1-800-292-2221. http://www.tmc.edu/thi/his.html.

Paula Ford-Martin

Teresa G. Odle

Heart Attack

Definition

A heart attack is the death of, or damage to, part of the heart muscle because the supply of blood to the heart muscle is severely reduced or stopped.

Description

Heart attack is the leading cause of death in the United States. More than 1.5 million Americans suffer a heart attack every year, and almost half a million die, according to the American Heart Association. Most heart attacks are the end result of years of silent but progressive coronary artery disease, which can be prevented in many people. A heart attack often is the first symptom of coronary artery disease. According to the American Heart Association, 63% of women and 48% of men who died suddenly of coronary artery disease had no previous symptoms. Heart attacks also are called myocardial infarctions (MIs).

A heart attack occurs when one or more of the coronary arteries that supply blood to the heart are completely blocked and blood to the heart muscle is cut off. The blockage usually is caused by atherosclerosis, the build-up of plaque in the artery walls, and/or by a blood clot in a coronary artery. Sometimes, a healthy or atherosclerotic coronary artery has a spasm and the blood flow to part of the heart decreases or stops. Why this happens is unclear, but it can result in a heart attack.

About half of all heart attack victims wait at least two hours before seeking help. This increases their chance of sudden death or being disabled. The longer the artery remains blocked during a heart attack, the more damage will be done to the heart. If the blood supply is cut off severely or for a long time, muscle cells suffer irreversible injury and die. This can cause the patient to die. That is why it is important to recognize the signs of a heart attack and seek prompt medical attention at the nearest hospital with 24-hour emergency cardiac care.

About one-fifth of all heart attacks are silent, that is, the victim does not know one has occurred. Although the victim feels no pain, silent heart attacks still can damage the heart.

The outcome of a heart attack also depends on where the blockage is, whether the heart rhythm is disturbed, and whether another coronary artery supplies blood to that part of the heart. Blockages in the left coronary artery usually are more serious than in the right coronary artery. Blockages that cause an arrhythmia, an irregular heartbeat, can cause sudden death.

Causes and symptoms

Heart attacks generally are caused by severe coronary artery disease. Most heart attacks are caused by blood clots that form on atherosclerotic plaque. This blocks a coronary artery from supplying oxygen-rich blood to part of the heart. A number of major and contributing risk factors increase the risk of developing coronary artery disease. Some of these can be changed and some cannot. People with more risk factors are more likely to develop coronary artery disease.

Major risk factors

Major risk factors significantly increase the risk of coronary artery disease. Those which cannot be changed are:

• Heredity. People whose parents have coronary artery disease are more likely to develop it. African Americans also are at increased risk, due to their higher rate of severe hypertension than whites.
• Sex. Men under the age of 60 years of age are more likely to have heart attacks than women of the same age.
• Age. Men over the age of 45 and women over the age of 55 are considered at risk. Older people (those over 65) are more likely to die of a heart attack. Older women are twice as likely to die within a few weeks of a heart attack as a man. This may be because of other co-existing medical problems.

Major risk factors that can be changed are:

• Smoking. Smoking greatly increases both the chance of developing coronary artery disease and the change of dying from it. Smokers have two to four times the risk of non-smokers of sudden cardiac death and are more than twice as likely to have a heart attack. They also are more likely to die within an hour of a heart attack. Second-hand smoke also may increase risk.
• High cholesterol. Cholesterol is a soft, waxy substance that is produced by the body, as well as obtained from eating foods such as meat, eggs, and other animal products. Cholesterol level is affected by age, sex, heredity, and diet. Risk of developing coronary artery disease increases as blood cholesterol levels increase. When combined with other factors, the risk is even greater. Total cholesterol of 240 mg/dL and over poses a high risk, and 200-239 mg/dL a borderline high risk. In LDL cholesterol, high risk starts at 130-159 mg/dL, depending on other risk factors. HDL (healthy cholesterol) can lower or raise the coronary risk also.
• High blood pressure. High blood pressure makes the heart work harder, and over time, weakens it. It increases the risk of heart attack, stroke, kidney failure, and congestive heart failure. A blood pressure of 140 over 90 or above is considered high. As the numbers increase, high blood pressure goes from Stage 1 (mild) to Stage 4 (very severe). When combined with obesity, smoking, high cholesterol, or diabetes, the risk of heart attack or stroke increases several times.
• Lack of physical activity. This increases the risk of coronary artery disease. Even modest physical activity is beneficial if done regularly.
• Use of certain drugs or supplements. Extreme caution is advised in the use of the herbal supplement ephedra. The supplement, which was marketed for weight loss and to improve athletic performance, was found to contribute to heart attack, seizure, stoke and death. In April 2003, the U.S. Food and Drug Administration (FDA) investigating controlling or banning the substance. While it was once believed that hormone replacement therapy (HRT) helped prevent heart disease in women, a large clinical trial called the Women's Health Initiative found the opposite to be true. In 2003, the FDA began requiring manufacturers of HRT to place warnings on the box listing adverse effects of estrogen, including increased risk of heart attack, stroke and blood clots. The labels also must mention that HRT should not be used as a preventive medicine for heart disease.

Contributing risk factors

Contributing risk factors have been linked to coronary artery disease, but their significance or prevalence cannot always be demonstrated. Contributing risk factors are:

• Diabetes mellitus. The risk of developing coronary artery disease is seriously increased for diabetics. More than 80% of diabetics die of some type of heart or blood vessel disease.
• Obesity. Excess weight increases the strain on the heart and increases the risk of developing coronary artery disease, even if no other risk factors are present. Obesity increases both blood pressure and blood cholesterol, and can lead to diabetes.
• Stress and anger. Some scientists believe that stress and anger can contribute to the development of coronary artery disease. Stress, the mental and physical reaction to life's irritations and challenges, increases the heart rate and blood pressure, and can injure the lining of the arteries. Evidence shows that anger increases the risk of dying from heart disease and more than doubles the risk of having a heart attack right after an episode of anger.
• Rheumatoid arthritis in women. A report released in 2003 noted that women with rheumatoid arthritis has a higher risk of heart attach than those without the condition. The reason is most likely the inflammation arthritis causes.

More than 60% of heart attack victims experience symptoms before the heart attack occurs. These sometimes occur days or weeks before the heart attack. Sometimes, people do not recognize the symptoms of a heart attack or are in denial that they are having one. Symptoms are:

• Uncomfortable pressure, fullness, squeezing, or pain in the center of the chest. This lasts more than a few minutes, or may go away and return.
• Pain that spreads to the shoulders, neck, or arms.
• Chest discomfort accompanied by lightheadedness, fainting, sweating, nausea, or shortness of breath.

All of these symptoms do not occur with every heart attack. Sometimes, symptoms disappear and then reappear. A person with any of these symptoms should immediately call an emergency rescue service or be driven to the nearest hospital with a 24-hour cardiac care unit, whichever is quicker.

Diagnosis

Experienced emergency care personnel usually can diagnose a heart attack simply by looking at the patient. To confirm this diagnosis, they talk with the patient, check heart rate and blood pressure, perform an electrocardiogram, and take a blood sample. The electrocardiogram shows which coronary artery is blocked. Electrodes covered with conducting jelly are placed on the patient's chest, arms, and legs. They send impulses of the heart's activity through an oscilloscope (a monitor) to a recorder, which traces them on paper. The blood test shows the leak of enzymes or other biochemical markers from damaged cells in the heart muscle. In 2003, the FDA cleared a new test for ruling out heart attacks in people who come to emergency rooms with severe chest pains. It is the first new blood test for evaluation of heart attacks since 1994 and is used along with an electrocardiogram.

Treatment

Heart attacks are treated with cardiopulmonary resuscitation (CPR) when necessary to start and keep the patient breathing and his heart beating. Additional treatment can include close monitoring, electric shock, drug therapy, re-vascularization procedures, percutaneous transluminal coronary angioplasty and coronary artery bypass surgery. Upon arrival at the hospital, the patient is closely monitored. An electrical-shock device, a defibrillator, may be used to restore a normal rhythm if the heartbeat is fluttering uncontrollably. Oxygen often is used to ease the heart's workload or to help victims of severe heart attack breathe easier. If oxygen is used within hours of the heart attack, it may help limit damage to the heart.

Drugs to stabilize the patient and limit damage to the heart include thrombolytics, aspirin, anticoagulants, painkillers and tranquilizers, beta-blockers, ace-inhibitors, nitrates, rhythm-stabilizing drugs, and diuretics. Drugs that limit damage to the heart work only if given within a few hours of the heart attack. Thrombolytic drugs that break up blood clots and enable oxygen-rich blood to flow through the blocked artery increase the patient's chance of survival if given as soon as possible after the heart attack. Thrombolytics given within a few hours after a heart attack are the most effective. Injected intravenously, these include anisoylated plasminogen streptokinase activator complex (APSAC) or anistreplase (Eminase), recombinant tissue-type plasminogen activator (r-tPA, Retevase, or Activase), and streptokinase (Streptase, Kabikinase).

To prevent additional heart attacks, aspirin and an anticoagulant drug often follow the thrombolytic drug. These prevent new blood clots from forming and existing blood clots from growing. Anticoagulant drugs help prevent the blood from clotting. The most common anticoagulants are heparin and warfarin. Heparin is given intravenously while the patient is in the hospital. Warfarin, taken orally, often is given later. Aspirin helps to prevent the dissolved blood clots from reforming.

To relieve pain, a nitroglycerine tablet taken under the tongue may be given. If the pain continues, morphine sulfate may be prescribed. Tranquilizers such as diazepam (Valium) and alprazolam (Ativan) may be prescribed to lessen the trauma of a heart attack.

To slow down the heart rate and give the heart a chance to heal, beta-blockers often are given intravenously right after the heart attack. These can also help prevent sometimes fatal ventricular fibrillation. Beta-blockers include atenolol (Tenormin), metoprolol (Lopressor), nadolol, pindolol (Visken), propranolol (Inderal), and timolol (Blocadren).

Nitrates, a type of vasodilator, also are given right after a heart attack to help improve the delivery of blood to the heart and ease heart failure symptoms. Nitrates include isosorbide mononitrate (Imdur), isosorbide dinitrate (Isordil, Sorbitrate), and nitroglycerin (Nitrostat).

When a heart attack causes an abnormal heart-beat, arrhythmia drugs may be given to restore the heart's normal rhythm. These include: amiodarone (Cordarone), atropine, bretylium, disopyramide (Norpace), lidocaine (Xylocaine), procainamide (Procan), propafenone (Rythmol), propranolol (Inderal), quinidine, and sotalol (Betapace). Angiotensin-converting enzyme (ACE) inhibitors reduce the resistance against which the heart beats and are used to manage and prevent heart failure. They are used to treat heart attack patients whose hearts do not pump well or who have symptoms of heart failure. Taken orally, they include Altace, Capoten, Lotensin, Monopril, Prinivil, Vasotec, and Zestril. Angiotensin receptor blockers, such as losartan (Cozaar) may substitute. Diuretics can help get rid of excess fluids that sometimes accumulate when the heart is not pumping effectively. Usually taken orally, they cause the body to dispose of fluids through urination. Common diuretics include: bumetanide (Bumex), chlorthalidone (Hygroton), chlorothiazide (Diuril), furosemide (Lasix), hydrochlorothiazide (HydroDIRUIL, Esidrix), spironolactone (Aldactone), and triamterene (Dyrenium).

Percutaneous transluminal coronary angioplasty and coronary artery bypass surgery are invasive revascularization procedures that open blocked coronary arteries and improve blood flow. They usually are performed only on patients for whom clot-dissolving drugs do not work, or who have poor exercise stress tests, poor left ventricular function, or ischemia. Generally, angioplasty is performed before coronary artery bypass surgery.

Percutaneous transluminal coronary angioplasty, usually called coronary angioplasty, is a non-surgical procedure in which a catheter (a tiny plastic tube) tipped with a balloon is threaded from a blood vessel in the thigh or arm into the blocked artery. The balloon is inflated and compresses the plaque to enlarge the blood vessel and open the blocked artery. The balloon is then deflated and the catheter is removed. Coronary angioplasty is performed in a hospital and generally requires a two-day stay. It is successful about 90% of the time. For one third of patients, the artery narrows again within six months after the procedure. The procedure can be repeated. It is less invasive and less expensive than coronary artery bypass surgery.

In coronary artery bypass surgery, called bypass surgery, a detour is built around the coronary artery blockage with a healthy leg or chest wall artery or vein. The healthy vein then supplies oxygen-rich blood to the heart. Bypass surgery is major surgery appropriate for patients with blockages in two or three major coronary arteries or severely narrowed left main coronary arteries, as well as those who have not responded to other treatments. It is performed in a hospital under general anesthesia using a heart-lung machine to support the patient while the healthy vein is attached to the coronary artery. About 70% of patients who have bypass surgery experience full relief from angina ; about 20% experience partial relief. Long term, symptoms recur in only about three or four percent of patients per year. Five years after bypass surgery, survival expectancy is 90%, at 10 years it is about 80%, at 15 years it is about 55%, and at 20 years it is about 40%.

There are several experimental surgical procedures for unblocking coronary arteries under study including: atherectomy, where the surgeon shaves off and removes strips of plaque from the blocked artery; laser angioplasty, where a catheter with a laser tip is inserted to burn or break down the plaque; and insertion of a metal coil called a stent that can be implanted permanently to keep a blocked artery open.

Prognosis

The aftermath of a heart attack is often severe. Two-thirds of heart attack patients never recover fully. Within one year, 27% of men and 44% of women die. Within six years, 23% of men and 31% of women have another heart attack, 13% of men and 6% of women experience sudden death, and about 20% have heart failure. People who survive a heart attack have a chance of sudden death that is four to six times greater than others and a chance of illness and death that is two to nine times greater. Older women are more likely than men to die within a few weeks of a heart attack. In 2003, a new drug showed some promise in helping patients who have had a heart attack and developed heart failure. Called eplerenone, it lowered the death rate and risk of sudden death among patients tested.

Prevention

Many heart attacks can be prevented through a healthy lifestyle, which can reduce the risk of developing coronary artery disease. For patients who have already had a heart attack, a healthy lifestyle and carefully following doctor's orders can prevent another heart attack. A heart healthy lifestyle includes eating right, regular exercise, maintaining a healthy weight, no smoking, moderate drinking, no illegal drugs, controlling hypertension, and managing stress.

A healthy diet includes a variety of foods that are low in fat (especially saturated fat), low in cholesterol, and high in fiber; plenty of fruits and vegetables; and limited sodium. Some foods are low in fat but high in cholesterol, and some are low in cholesterol but high in fat. Saturated fat raises cholesterol, and, in excessive amounts, it increases the amount of the proteins in blood that form blood clots. Polyunsaturated and monounsaturated fats are relatively good for the heart. Fat should comprise no more than 30 percent of total daily calories.

Cholesterol, a waxy, lipid-like substance, comes from eating foods such as meat, eggs, and other animal products. It also is produced in the liver. Soluble fiber can help lower cholesterol. Cholesterol should be limited to about 300 mg per day. Many popular lipid-lowering drugs can reduce LDL-cholesterol by an average of 25-30% when combined with a low-fat, low-cholesterol diet. Fruits and vegetables are rich in fiber, vitamins, and minerals. They are also low calorie and nearly fat free. Vitamin C and beta-carotene, found in many fruits and vegetables, keep LDL-cholesterol from turning into a form that damages coronary arteries. Excess sodium can increase the risk of high blood pressure. Many processed foods contain large amounts of sodium, which should be limited to a daily intake of 2,400 mg—about the amount in a teaspoon of salt.

The "Food Guide" Pyramid developed by the U.S. Departments of Agriculture and Health and Human Services provides easy to follow guidelines for daily heart-healthy eating: six to 11 servings of bread, cereal, rice, and pasta; three to five servings of vegetables; two to four servings of fruit; two to three servings of milk, yogurt, and cheese; and two to three servings of meat, poultry, fish, dry beans, eggs, and nuts. Fats, oils, and sweets should be used sparingly.

Regular aerobic exercise can lower blood pressure, help control weight, and increase HDL ("good") cholesterol. It may keep the blood vessels more flexible. Moderate intensity aerobic exercise lasting about 30 minutes four or more times per week is recommended for maximum heart health, according to the Centers for Disease Control and Prevention and the American College of Sports Medicine. Three 10-minute exercise periods also are beneficial. Aerobic exercise—activities such as walking, jogging, and cycling—uses the large muscle groups and forces the body to use oxygen more efficiently. It also can include everyday activities such as active gardening, climbing stairs, or brisk housework.

Maintaining a desirable body weight also is important. About one-fourth of all Americans are overweight, and nearly one-tenth are obese, according to the Surgeon General's Report on Nutrition and Health. People who are 20% or more over their ideal body weight have an increased risk of developing coronary artery disease. Losing weight can help reduce total and LDL cholesterol, reduce triglycerides, and boost relative levels of HDL cholesterol. It also may reduce blood pressure.

Smoking has many adverse effects on the heart. It increases the heart rate, constricts major arteries, and can create irregular heartbeats. It also raises blood pressure, contributes to the development of plaque, increases the formation of blood clots, and causes blood platelets to cluster and impede blood flow. Heart damage caused by smoking can be repaired by quitting—even heavy smokers can return to heart health. Several studies have shown that ex-smokers face the same risk of heart disease as non-smokers within five to 10 years of quitting.

Drinking should be done in moderation. Modest consumption of alcohol can actually protect against coronary artery disease. This is believed to be because alcohol raises HDL cholesterol levels. The American Heart Association defines moderate consumption as one ounce of alcohol per day—roughly one cocktail, one 8-ounce glass of wine, or two 12-ounce glasses of beer. A study released in 2003 reported that risk of heart attack in men was reduced 30% to 35 % if they drank moderate amounts of alcoholic beverages three or four times a week. In some people, however, moderate drinking can increase risk factors for heart disease, such as raising blood pressure. Excessive drinking is always bad for the heart. It usually raises blood pressure, and can poison the heart and cause abnormal heart rhythms or even heart failure. Illegal drugs, like cocaine, can seriously harm the heart and should never be used.

High blood pressure, one of the most common and serious risk factors for coronary artery disease, can be completely controlled through lifestyle changes and medication. People with moderate hypertension may be able to control it through lifestyle changes such as reducing sodium and fat, exercising regularly, managing stress, quitting smoking, and drinking alcohol in moderation. If these changes do not work, and for people with severe hypertension, there are eight types of drugs that provide effective treatment.

Stress management means controlling mental and physical reactions to life's irritations and challenges. Techniques for controlling stress include: taking life more slowly, spending time with family and friends, thinking positively, getting enough sleep, exercising, and practicing relaxation techniques.

Daily aspirin therapy has been proven to help prevent blood clots associated with atherosclerosis. It also can prevent heart attacks from recurring, prevent heart attacks from being fatal, and lower the risk of strokes.

Resources

PERIODICALS

"First New Blood Test to Evaluate Heart Attacks." Biomedical Market Newsletter January-February 2003: 42.

"Heart Attacks Reduced by Alchohol." The Lancet January 11, 2003: 149.

Kirn, Timothy F. "FDA Probes Ephedra, Proposes Warning Label (Risk of Heart Attack, Seizure, Stroke)." Clinical Psychiatry News April 2003: 49.

Pitt, Bertram, et al. "Eplerenone, a Selective Aldosterone Blocker, in Patients with Left Ventricular Dysfunction after Myocardial Infarction." The New England Journal of Medicine April 3, 2003: 1309-1313.

Stephenson, Joan. "FDA Orders Estrogen Safety Warnings: Agency Offers Guidance for HRT Use." JAMA February 5, 2003: 537.

ORGANIZATIONS

American Heart Association. 7320 Greenville Ave. Dallas, TX 75231. (214) 373-6300. 〈http://www.americanheart.org〉.

National Heart, Lung and Blood Institute. PO Box 30105, Bethesda, MD 20824-0105. (301) 251-1222. 〈http://www.nhlbi.nih.gov〉.

Texas Heart Institute. Heart Information Service. PO Box 20345, Houston, TX 77225-0345. 〈http://www.tmc.edu/thi〉.

KEY TERMS

Angina— Chest pain that happens when diseased blood vessels restrict the flow of blood to the heart. Angina often is the first symptom of coronary artery disease.

Atherosclerosis— A process in which the walls of the coronary arteries thicken due to the accumulation of plaque in the blood vessels. Atherosclerosis is the cause of coronary artery disease.

Coronary arteries— The two arteries that provide blood to the heart. The coronary arteries surround the heart like a crown, coming out of the aorta, arching down over the top of the heart, and dividing into two branches. These are the arteries where coronary artery disease occurs.

Myocardial infarction— The technical term for heart attack. Myocardial means heart muscle and infarction means death of tissue from lack of oxygen.

Plaque— A deposit of fatty and other substances that accumulate in the lining of the artery wall.

HEART ATTACK

DEFINITION

A heart attack is caused by the death of, or damage to, part of the heart muscle. Heart attacks usually occur because the supply of blood to the heart muscle is greatly reduced or stopped. A heart attack is also called a myocardial infarction (pronounced my-uh-KAR-dee-al in-FARK-shun).

DESCRIPTION

Heart attack is the leading cause of death in the United States. More than 1.5 million Americans suffer a heart attack each year. About one-third of them die from the heart attack.

The conditions leading to a heart attack often develop over many years. Like all organs in the body, the heart requires a constant supply of blood. It gets that blood from arteries that lead into the heart. In some cases, plaque (pronounced PLAK) may build up on artery walls. Plaque is a collection of cells deposited on the walls of the artery. Over time, the plaque becomes larger and larger. Eventually, it greatly reduces the amount of blood reaching the heart. The plaque can also close off the artery entirely. When that happens, the blood supply to the heart is completely cut off. In such cases, heart cells die and a heart attack occurs.

Heart Attack: Words to Know

Anticoagulant:

Able to prevent a blood clot from forming.

Coronary:

Referring to the heart.

Myocardial infarction:

The technical term for heart attack.

Plaque:

A deposit of fatty material and other substances that forms on the lining of a blood vessel.

Thrombolytic:

Capable of dissolving a blood clot.

The prognosis for a heart attack depends greatly on how quickly it is treated. The longer the blood supply is reduced, the more heart muscle cells die.

About one-fifth of all heart attacks are "silent." The patient usually feels no pain. He or she does not realize that a heart attack has occurred. Still, silent heart attacks can cause damage to the heart.

CAUSES

Heart attacks are usually caused by severe coronary artery disease (CAD). CAD is any condition that affects the coronary arteries. The coronary arteries are the blood vessels that supply blood to the heart. Plaque in an artery is a common type of coronary artery disease.

Major Risk Factors

A number of risk factors increase the chance of developing coronary artery disease. Some major risk factors can be changed and others cannot. Among those that cannot be changed are the following:

• Heredity. People whose parents have CAD are more likely to develop the condition. African Americans are also at increased risk for CAD.
• Gender. Men under the age of sixty are more likely to have heart attacks than women of the same age.
• Age. Men over the age of forty-five and women over the age of fifty-five are at higher risk than younger people. People over the age of sixty-five are more likely to die of a heart attack.

Some risk factors that can be changed are:

• Smoking. Smokers are more than twice as likely to have a heart attack than nonsmokers. They are 2 to 4 times more likely to die of a heart attack.
• High cholesterol. Cholesterol is a material that occurs naturally in all animals, including humans. It has many important biological functions. High levels of cholesterol in the blood, however, may increase the chance that plaque will form in blood vessels. It contributes to the risk of CAD and heart attack.
• High blood pressure. High blood pressure (see hypertension entry) makes the heart work harder. Over time, the heart becomes weaker. High blood pressure also increases the risk of stroke, kidney failure, and other types of heart disease.
• Lack of physical exercise. Even modest physical activity can be helpful if done regularly.

Contributing Risk Factors

Other conditions may affect the risk of CAD and heart attack. Scientists are not certain how these factors are involved in these conditions, however. The factors are:

• Diabetes mellitus (see diabetes mellitus entry). People with diabetes are at much higher risk for heart attack. About 80 percent of all diabetics die of some type of heart or blood vessel disease.
• Obesity (see obesity entry). Excess weight places a strain on the heart. It increases the risk of CAD and heart attack.
• Stress and anger. Stress and anger both increase blood pressure and heart rate. Some researchers think that these emotions can contribute to the chance of heart attack.

Many of the above risk factors are related to each other. For example, obesity and stress both contribute to high blood pressure. People with more than one risk factor are even more likely to develop CAD and have a heart attack.

SYMPTOMS

More than 60 percent of heart attack patients experience symptoms before the attack actually begins. These symptoms sometimes occur days or weeks ahead of time. Unfortunately, many people do not know the symptoms of heart attack, or they prefer not to recognize those symptoms when they appear. Typical symptoms include:

• Uncomfortable pressure, fullness, squeezing, or pain in the center of the chest. The pain may last for a few minutes, or it may go away and return.
• Pain that spreads to the shoulders, neck, or arms.
• Chest discomfort accompanied by light-headedness, fainting, sweating, nausea, or shortness of breath.

All symptoms do not occur with every heart attack. Symptoms sometimes disappear and then reappear. A person with these symptoms should receive immediate medical attention.

DIAGNOSIS

People who are familiar with heart attacks can usually diagnose the condition simply by looking at a patient. To confirm the diagnosis, the patient's heart rate and blood pressure may be measured. Both an electrocardiogram (pronounced ih-LEK-tro-KAR-dee-o-gram) and blood tests provide further evidence for a heart attack. An electrocardiogram is a test that measures the electrical function of the heart.

TREATMENT

The first stage in treating a heart attack usually involves steps simply to keep the patient alive. If the patient has stopped breathing, cardiopulmonary resuscitation (CPR; pronounced car-dee-oh-PULL-mon-air-ee ree-sus-i-ta-shun) may be needed. CPR may involve breathing into the patient's mouth or pushing on the chest to restore breathing.

Once a patient has reached the hospital, a number of other emergency treatments may be necessary. For example, defibrillation may be required. Defibrillation (pronounced DEE-fib-ri-lay-shun) is used if the patient's heart is beating in an irregular pattern. An electric shock is applied to the patient's chest. The shock causes the heart to stop beating briefly. The heart then begins to beat again, in a more regular pattern.

A patient may also require oxygen therapy. In oxygen therapy, the patient is allowed to breathe air to which extra oxygen has been added. The extra oxygen makes it easier for the heart to work. Oxygen therapy can reduce the damage done to the heart.

Drug Treatments

A variety of drugs may be given following a heart attack. Some examples of these drugs are:

• Thrombolytics. Thrombolytic (pronounced throm-buh-LIH-tik) drugs are chemicals that dissolve blood clots. The most widely used of these drugs is tissue plasminogen activator (tPA). Patients who receive tPA within hours after a heart attack have a greatly increased chance of survival.
• Anticoagulants. Anticoagulants are drugs that thin the blood. Blood thinners reduce the chance that new blood clots will form. Aspirin is one of the most common and most effective blood thinners. Two other blood thinners are warfarin and heparin.
• Pain relief. Nitroglycerin (pronounced nite-roh-GLIS-er-in) tablets are commonly used to treat pain. In more severe cases, morphine may be needed to control pain.

• Tranquilizers . Heart attack patients are often extremely upset. Tranquilizers such as diazepam (pronounced di-AZE-uh-pam, trade name Valium) can help relieve emotional distress.
• Beta-blockers. Beta-blockers slow down the heart rate. They give the heart a chance to start healing. They may also prevent the development of an irregular heart beat.
• Vasodilators. Vasodilators cause blood vessels to open up. This makes it easier for blood to flow through them and reduces the work the heart has to do.
• Drugs that control arrhythmia (pronounced uh-RITH-mee-uh). These drugs help the heart to pump at a regular rate. They reduce the risk that abnormal and potentially fatal irregular heart rhythms may develop.

The key to surviving a heart attack is to open the blood vessels to the heart again. In many cases, thrombolytics and anticoagulants can achieve this goal. When they cannot, surgery may be necessary.

Surgery

Two forms of surgery are often used with heart attack patients. The first is called coronary angioplasty (pronounced AN-jee-o-PLAS-tee). The tool used for coronary angioplasty is a catheter with an empty balloon attached at one end. The catheter is a thin plastic tube that can be inserted into a patient's artery, usually in the thigh or arm. It is then threaded up the artery until it gets to the blocked coronary artery.

At that point, the balloon is inflated. The inflated balloon pushes on the plaque that is blocking the artery and opens up the artery. Blood is able to flow more freely into the heart. The balloon is then deflated, and the catheter removed from the person's body.

Angioplasty is initially successful in about 90 percent of all cases. In about one-third of all cases, the artery narrows again after the procedure. In such cases, the procedure can be repeated.

The second surgical procedure is called bypass surgery. The purpose of bypass surgery is to provide a new pathway for blood to reach the heart. The procedure requires three steps. First, a section of healthy vein is removed from some part of the patient's body, such as a leg or arm. Then a cut is made just below and just above the blockage in the patient's coronary artery. Finally, the healthy vein is attached to the coronary artery. The attached vein provides a new pathway around the blocked section of the artery.

Coronary bypasses are completely successful in about 70 percent of all cases. In another 20 percent of cases, partial relief is obtained. Five years after surgery, the survival rate (the number of patients still alive) for patients who have had a coronary bypass is about 90 percent. It is as high as 80 percent even after ten years.

PROGNOSIS

The aftermath of a heart attack is often severe. Two-thirds of all heart attack patients never recover fully. About one-quarter of all men and nearly one-half of all women who have had heart attacks die within a year. Additional heart attacks are not unusual. About one-quarter of all men and one-third of all women have a second heart attack within six years.

PREVENTION

Some risk factors for heart attack cannot be controlled. There may be hereditary factors that make a person more or less likely to have CAD and a heart attack. However, many risk factors can be managed. Some ways a person can reduce the risk of CAD and heart attack are:

• Eat a healthy diet that includes a variety of foods low in fat, low in cholesterol, and high in fiber. The diet should include plenty of fruits and vegetables, and limited sodium.
• Get regular moderate exercise that lasts for thirty minutes, four or more times per week. Helpful forms of exercise include walking, jogging, cycling, and swimming. Everyday activities, such as active gardening, climbing stairs, and brisk housework, can also help.
• Maintain a proper body weight by watching one's diet and exercising.
• Stop smoking or don't start smoking. People who quit smoking gradually become less at risk for CAD and heart attack.
• Adults should consume only moderate amounts of alcohol. In some adults moderate drinking is not necessarily bad for the body and may even help protect against CAD. Excessive drinking is bad, however, because it raises blood pressure and can produce toxins (poisons) in the body.
• Adopt a more moderate lifestyle that reduces stress and anxiety. This kind of change may contribute to lower blood pressure and reduced risk of CAD and heart attack.
• Take one aspirin tablet per day. Aspirin helps thin the blood and reduce the risk of a blood clot forming.

FOR MORE INFORMATION

Books

American Heart Association. Guide to Heart Attack Treatment, Recovery, Prevention. New York: Time Books, 1996.

American Heart Association. Your Heart: An Owner's Manual. Englewood Cliffs, NJ: Prentice Hall, 1995.

DeBakey, Michael E., and Antonio M. Grotto, Jr. The New Living Heart. Holbrook, MA: Adams Media Corporation, 1997.

McGoon, Michael D. Mayo Clinic Heart Book. New York: William Morrow & Company, 1993.

Notelovitz, Morris, and Diana Tonnessen. The Essential Heart Book for Women. New York: St. Martin's Press, 1996.

Organizations

American Heart Association. National Center. 7272 Greenville Ave., Dallas, TX 75231-4596. (214) 373–6300. http://www.medsearch.com/pf/profiles/amerh.

National Heart, Lung, and Blood Institute Information Center. PO Box 30105. Bethesda, MD 20824-0105. http://www.nhlbi/nibli.htm.

Web sites

"Ask NOAH About: Heart Disease and Stroke." NOAH: New York Online Access to Health. [Online] http://www.noah.cuny.edu/heart_disease/heartdisease.html#H (accessed on October 22, 1999).

Heart attack

Definition

A heart attack, which is also called a myocardial infarction (MI), is the death or damage of part of the heart muscle because the supply of blood to the heart muscle is sharply reduced or stopped.

Description

A heart attack occurs when one or more of the coronary arteries that supply blood to the heart are completely blocked and blood to the heart muscle is cut off. The blockage is usually caused by athero-sclerosis , the build-up of plaque in artery walls, and/or by a blood clot in a coronary artery. Sometimes, a healthy or atherosclerotic coronary artery has a spasm and the blood flow to part of the heart decreases or stops, resulting in a heart attack.

Demographics

Generally, heart attacks occur in persons over age 40 and most are in those ages 50 to 70. Between the

ages of 40 to 65, more men than women suffer heart attacks; after age 65 the gender difference disappears.

Causes and symptoms

Heart attacks are generally caused by severe coronary artery disease. Most are caused by blood clots that form on atherosclerotic plaque, which impedes the supply of blood to part of the heart. A number of major and contributing risk factors increase the likelihood of developing coronary artery disease. Some of these risk factors can be modified, but others cannot. Persons with more risk factors are more likely to develop coronary artery disease.

Major risk factors

Major risk factors significantly increase the likelihood of developing coronary artery disease. Risk factors that cannot be changed include:

• Heredity. People whose parents have coronary artery disease, particularly those who develop it at younger ages, are more likely to be diagnosed with it.
• Gender. Men under the age of 60 years of age are more likely to have myocardial infarctions than women of the same age.
• Age. Men over age 45 and women over age 55 are considered at risk. Older adults (those over 65) are more likely to die as a result of a heart attack. Older women are twice as likely to die within a few weeks of a heart attack as men.

Major risk factors which can be changed are:

• Smoking greatly increases both the risk of developing coronary artery disease and the chance of dying from it. Smokers are more than twice as likely to have a heart attack. They are also more likely to die within an hour of a heart attack. Second-hand smoke may also increase risk.
• High cholesterol levels increase the risk of developing coronary artery disease. When combined with other factors, the risk is even greater. Low levels of HDL (high-density lipoprotein) increase the risk of coronary artery disease; highHDLprotects against it.
• High blood pressure makes the heart work harder, and over time, weakens it. When high blood pressure is combined with obesity, smoking, high cholesterol, or diabetes, the risk of heart attack or stroke increases.
• Sedentary lifestyle and lack of physical activity increase the risk of heart disease. Even modest physical activity is beneficial if done regularly.

QUESTIONS TO ASK YOUR DOCTOR

• How can I help to prevent a second heart attack?
• Is exercise safe after a heart attack?
• Is sexual activity safe after having a heart attack?

Contributing risk factors

Contributing risk factors have been linked to coronary artery disease, but their significance and prevalence are not known yet. Contributing risk factors are:

• Diabetes increases the risk of developing heart disease.
• Obesity increases the strain on the heart muscle and increases the risk of developing heart disease, even if no other risk factors are present. Obesity increases both blood pressure and blood cholesterol, and can lead to diabetes.
• Stress and anger can produce physiological changes that contribute to the development of coronary artery disease. Stress increases heart rate and blood pressure, and can injure the lining of the arteries. Evidence shows that anger increases the risk of dying from heart disease and more than doubles the risk of having a heart attack right after an episode of anger.

More than 60% of patients experience symptoms before the heart attack occurs. These symptoms may occur days or weeks before the heart attack. Common symptoms include:

• Uncomfortable pressure, fullness, heaviness, squeezing, or pain in the center of the chest. The sensation lasts more than a few minutes, or may go away and return.
• Pain that spreads to the shoulders, neck, left arm, or jaw.
• Chest discomfort accompanied by lightheadedness, fainting, sweating, nausea, or shortness of breath.

All of these symptoms do not necessarily occur with every heart attack. Sometimes, symptoms disappear and then reappear. Persons with any of these symptoms should immediately call an emergency rescue service or be driven to the nearest hospital with a 24-hour cardiac care unit, whichever is quicker.

Diagnosis

Experienced emergency medical personnel confirm the diagnosis of heart attack by taking a thorough history, checking heart rate and blood pressure , performing an electrocardiogram (ECG), and drawing a blood sample. The ECG shows which coronary artery is blocked. The blood test detects the leak of enzymes or other biochemical markers from damaged cells in the heart muscle.

Treatment

Treatment usually begins in the emergency department with thrombolytic agents, aspirin , oxygen, and beta-blockers. Oxygen eases the heart's workload and can help patients breathe easier. If oxygen is administered within hours of the heart attack, it also may help limit damage to the heart. Subsequent treatment includes close monitoring; nitrates and morphine if needed; electric shock; drug therapy; revascularization procedures; coronary angioplasty ; and coronary artery bypass surgery.

Patients with complications such as arrhythmias, congestive heart failure , and blood pressure problems require additional treatment. A defibrillator may be used to restore a normal rhythm. A temporary pacemaker may be inserted to correct a slow heart rate. Ace inhibitors may be used to treat congestive heart failure.

Drugs to and limit damage to the heart include thrombolytics, aspirin, anticoagulants, painkillers, and tranquilizers, beta-blockers, ace-inhibitors, nitrates, anti-arrhthythmics (rhythm-stabilizing) drugs, and diuretics . Thrombolytics, used to limit damage to the heart, work only if given within 6–12 hours of the onset (when the chest pain began) of the heart attack. Thrombolytic drugs act by dissolving the blood clot that is blocking the acutely occluded coronary artery. They increase the likelihood of survival when given as soon as possible after the heart attack.

Nutrition/Dietetic concerns

Maintaining a healthy body weight is vital for heart health. People who are 20% or more over their ideal body weight are at increased risk of developing coronary artery disease. Losing weight can help reduce total and LDL cholesterol, reduce triglycerides, and boost relative levels of HDL cholesterol. It may also reduce blood pressure.

Prognosis

The aftermath of a myocardial infarction is often severe. Thirty percent of patients die as a result of a heart attack. People who survive have a chance of sudden death that is four to six times greater than others and a chance of illness and death that is two to nine times greater. In general, the smaller the amount of heart muscle affected, the better the prognosis. Other factors that affect prognosis include age and the presence of other coexisting illnesses such as diabetes or high blood pressure. The outlook also depends on whether patients adhere to medical treatment and take action to eliminate or reduce modifiable risk factors.

KEY TERMS

Angina —Chest pain that occurs when diseased blood vessels restrict the flow of blood to the heart. Angina is often the first symptom of coronary artery disease.

Atherosclerosis —A process in which the walls of the coronary arteries thicken due to the accumulation of plaque in the blood vessels. Atherosclerosis is the cause of coronary artery disease.

Coronary arteries —The two arteries that provide blood to the heart. The coronary arteries surround the heart like a crown, coming out of the aorta, arching down over the top of the heart, and dividing into two branches. These are the arteries where coronary artery disease occurs.

Myocardial infarction —The medical, technical term for heart attack. Myocardial means heart muscle and infarction means death of tissue from lack of oxygen.

Plaque —A deposit of fatty and other substances that accumulate in the lining of the artery wall.

Prevention

Many heart attacks can be prevented through a healthy lifestyle, which can reduce the risk of developing heart disease . For patients who have already had a heart attack, a healthy lifestyle can prevent another heart attack. A heart healthy lifestyle includes a low-fat diet , regular exercise , maintaining a healthy weight, no smoking , moderate drinking, controlling high blood pressure, and managing stress .

Daily aspirin therapy has been proven to help prevent blood clots associated with atherosclerosis. It can also prevent heart attacks from recurring, prevent them from being fatal, and reduce the risk of strokes.

Caregiver concerns

Depression is a common repercussion of a heart attack, as well as a common side effect of medications used to treat patients who have suffered heart attacks. Care givers and family members also should be sensitive to the fact that diminished tolerance for physical exertion can limit a heart attack patient's ability to participate in physically demanding activities. Many patients are fearful about safely engaging in sexual activity after suffering a heart attack and may benefit from counseling to help allay their fears.

Resources

BOOKS

Zipes DP, Libby P, Bonow RO, Braunwald E, eds. Braunwald's heart disease: a textbook of cardiovascular medicine, 7th ed. Philadelphia: Saunders, 2005.

PERIODICALS

AHA; ACC; National Heart, Lung, and Blood Institute; Smith SC Jr, Allen J, Blair SN, et al. “AHA/ACC guidelines for secondary prevention for patients with coronary and other atherosclerotic vascular disease:2006 update". Endorsed by the National Heart, Lung, and Blood Institute. Journal of the American College Cardiology vol.16, no.10, May 2006

Boersma E, Mercado N, Poldermans D, et al. “Acute myocardial infarction.” Lancet vol.361, no.9374, June 14, 2003

ORGANIZATIONS

American Heart Association, 7272 Greenville Avenue, Dallas, TX, 75231, 301 592-8573, 800 242-8721, 301 592-8563, http://www.americanheart.org.

National Heart, Lung, and Blood Institute, PO Box 30105, Bethesda, MD, 20824-0105, 301 592-8573, 800 242 8721, 301 592-8563, http://www.nhlbi.nih.gov.

Barbara Wexler MPH

heart attack This term is most often used to describe the signs and symptoms associated with acute myocardial infarction, the sudden interruption or inadequacy of blood flow (ischaemia) to sections of the heart itself. If the inadequate blood flow persists for several minutes it can cause the affected section of heart muscle to die. The dead cells become replaced with scar tissue, and the dead area is known as an infarct. The immediate problem, however, is that the effectiveness of the heart's pumping action is abruptly reduced. Loss of function in any part of the heart will obviously reduce the strength of the pump. But a potentially greater threat is that damage, even to a small area, can induce within it erratic, spontaneous electrical activity. (Similar, but not dangerous, phenomena are sometimes seen in limb muscles when they twitch involuntarily if they or their associated nerve fibres, are underperfused with blood.) Since each heart cell is in electrical contact with its neighbours, the erratic activity is conducted to other, non-infarcted regions. If the electrical disturbance is serious enough, it can cause cardiac arrest.

Heart attack is a distressingly common clinical problem in many (but not all) Western developed societies. The incidence in the UK is about 150 000 per annum, of which nearly half prove fatal. (This can be judged against a total UK mortality of about half a million per annum.) The major cause of myocardial infarction in Western society is progressive coronary artery disease. The coronary arteries are the first blood vessels to branch from the aorta (the large artery leaving the heart). Although only two coronary arteries arise directly from the aorta, these branch extensively, forming an intricate network of vessels supplying all areas of the heart muscle with oxygenated blood. The arrangement of this ‘plumbing’ system makes the heart peculiarly vulnerable to interruptions of supply. In most other tissues, there are significant alternative routes by which arterial blood can reach any one region; so-called collateral supplies. Thus the cells of the heart are like leaves on a tree; they are at the end of the furthest twigs of the supply system. By contrast, in other tissues, the supply is more like a road network; very few houses are at the end of cul-de-sacs, most can be reached from several directions. If the flow of blood is stopped in one of the branches in our ‘tree’ analogy, the heart cells downstream, beyond the block, will inevitably suffer. (It is sobering to note that many other mammalian species do not have their hearts ‘plumbed’ so extensively this way. But the pig and several breeds of dog do suffer the risks of this ‘design flaw’ much like us.)

Typical signs of coronary artery disease include a painful feeling of ‘tightness’ in the chest or ‘heaviness’ brought on by physical effort, heavy meals, cold weather, or emotional stress. The sensation starts behind the breast bone and radiates across the chest. The pain is frequently confused with that of severe indigestion. Frequently, it is associated with a leaden feeling in the arms. Occasionally the sensation may be perceived in more unusual sites (e.g. in the jaws or teeth). An abnormal sensation of breathlessness on effort or at rest can occur, known as dyspnoea. Patients often feel cool, yet clammy or sticky to touch, and sometimes have dilated hand veins. If the symptoms are relieved by rest then this tends to indicate a serious narrowing of the coronary artery circulation (stable angina pectoris) rather than actual blockage. If the symptoms occur whilst at rest, or are not relieved by rest, they could indicate a heart attack. The severity of the symptoms is often indicative; patients may report a sense of impending doom, the chest pains are severe, vice-like, and persistent; the attack itself may provoke collapse, often without warning.

Coronary artery disease, with its ultimate sequel of myocardial infarction, is almost always due to atherosclerosis. The initiating event in the development of atherosclerosis is thought to be damage to the layer of cells lining the inner surface of the artery. Such injury triggers blood-borne factors to stimulate proliferation of cells within the wall of the artery and deposition of protein and cholesterol, known as an atheromatous plaque, that narrows the artery. In the majority of cases, the cracking of the atheromatous plaque causing a sudden blockage of the artery is the event which results in progression from atherosclerosis to infarction. Only very rarely is a myocardial infarction produced by other factors (e.g. a spasm within artery). It should be clear that if ejection of blood from the heart is suddenly reduced for any reason, the heart itself will receive an inadequate supply which can precipitate heart attack. In this category comes a variety of causes such as drug overdose, major haemorrhage, electric shock, and so on.

Treatment of coronary artery disease, thereby reducing the risk of heart attack, has many elements. It involves alterations to lifestyle, exclusion or treatment of precipitating factors, drug treatment, and surgery if medical treatment fails. Alteration in lifestyle involves a reduction in physical activity in work and the home. It may require a change of job. Smoking must stop and weight reduction may be required. Many socially related activities can be continued with medical treatment. The most important precipitating factors for coronary artery disease are high blood pressure, diabetes, and high cholesterol levels in the blood. These factors can largely be treated or controlled by diet and drugs; such treatment could prevent the progression of coronary artery disease to myocardial infarction. In the main, drug therapy involves drugs that act to dilate the blood vessels or reduce the contractility (and thereby oxygen requirements) of the heart muscle receiving a reduced blood supply. Surgical approaches to coronary artery disease include coronary artery bypass (where a vein is connected to the aorta and to the coronary artery beyond the narrowed region to improve blood flow) and coronary angioplasty (where a catheter containing a fine, elongated balloon is guided from the main leg artery into the coronary artery, positioned within the region of narrowing, and then briefly inflated, forcing open the narrowing).

David J. Miller, and Niall G. MacFarlane