Heart Attack Health Article

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.