Coronary Artery Disease Health Article

Definition

Coronary artery disease is a stenosis (narrowing) or blockage of the arteries and vessels that provide oxygenated blood to the heart. It is caused by atherosclerosis (hardening of the arteries), an accumulation of fatty plaque on the inner linings of arteries. The resulting blockage restricts blood flow through the coronary arteries. When blood flow is completely cut off, the result is myocardial infarction (heart attack).

Description

Coronary artery disease, also called coronary heart disease or atherosclerotic heart disease, is the leading cause of death for men and women in the United States. According to the American Heart Association, in 1998 one in every five deaths in the United States was caused by coronary artery disease. About every 29 seconds one American will have a heart attack; about every minute one American will die from a heart attack. Fourteen million Americans have active symptoms of coronary artery disease. Many millions more have asymptomatic (silent) coronary disease, the first indication of which can be sudden death.

Coronary artery disease occurs when the coronary arteries become partially blocked or clogged, thereby depriving the heart muscle of oxygen (myocardial ischemia). When the blockage is temporary or partial, angina (chest pain or pressure) may occur. When the blockage completely and suddenly cuts off the flow of blood, the result is myocardial infarction.

Healthy coronary arteries are clean, smooth, and slick. The artery walls are flexible and can expand to let more blood through when the heart needs to work harder. Atherosclerosis is thought to begin with an injury to the linings of the inner walls of the arteries. This injury makes them susceptible to atherosclerosis and thrombosis (blood clots).

Causes and symptoms

Coronary artery disease is usually caused by athero- sclerosis. Cholesterol and other fatty substances accumulate on the inner wall of the arteries. This attracts fibrous tissue, blood components, and calcium, which harden into flow-obstructing plaques. If a blood clot suddenly forms on one of these plaques it can convert a partial obstruction to a total occlusion. This is known as coronary thrombosis. Congenital defects and spasms of a coronary artery may also block blood flow. There is evidence that infection from organisms such as chlamydia bacteria may be responsible for some cases of coronary artery disease.

A number of major contributing factors increase the risk of developing coronary artery disease. Some risk factors can be modified and others cannot. Persons with more of these risk factors are at greater risk of developing coronary artery disease.

Major risk factors

Major risk factors significantly increase the chance 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. African- Americans are also at increased risk because they experience rience a higher rate of severe hypertension than whites.
• Gender. Men under the age of 60 years of age are more likely to have myocardial infarctions than women of the same age. Over age 60, however, women have coronary artery disease at a rate equal to that of men.
• Age. Men over age 45 and women over age 55 years are more likely to have coronary artery disease. Occasionally, coronary disease affects individuals in the 30s. Older adults (those over 65) are more likely to die of a myocardial infarction. Older women are twice as likely as older men to die within a few weeks of a myocardial infarction.

Major risk factors that can be changed are:

• Smoking. Smoking greatly increases both the risk of developing coronary artery disease and resulting mortality. Smokers have two to four times the risk of nonsmokers for sudden cardiac death and are more than twice as likely to have a myocardial infarction. They are also more likely to die within an hour of a heart attack. Second-hand smoke may also increase risk.
• High cholesterol. Cholesterol is produced by the body, and obtained from eating animal products such as meat, eggs, milk, and cheese. Age, gender, heredity, and diet affect cholesterol level. 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 or more poses a high risk, and 200–239 mg/dL a borderline high risk. For LDL (low-density lipoprotein) cholesterol, high risk starts at 130–159 mg/dL, depending on other risk factors. Low levels of HDL (high-density lipoprotein) increases the risk of coronary disease; high HDL protects against it.
• Hypertension (high blood pressure). High blood pressure makes the heart work harder, and over time, weakens it. It increases the risk of myocardial infarction, stroke, kidney failure, and congestive heart failure. Blood pressure of 140 over 90 or above is considered high. When hypertension is combined with obesity, smoking, high cholesterol, or diabetes, the risk of myocardial infarction or stroke increases several times.
• Sedentary lifestyle and lack of physical activity. Inactivity increases the risk of coronary artery dis- ease. Even modest physical activity is beneficial if done regularly.
• Diabetes mellitus. The risk of developing coronary artery disease is significantly increased for diabetics. More than 80% of diabetics die of some type of cardiovascular disease.