Heart attacks result from blood vessel disease in the heart. Coronary heart disease (CHD) and coronary artery disease (CAD) are more specific names for heart disease.

What causes a heart attack?

A heart attack, also known as myocardial infarction, occurs when the blood supply to part of the heart muscle itself--the myocardium--is severely reduced or stopped. This occurs when one of the arteries that supplies blood to the heart muscle (coronary arteries) is blocked by an obstruction. The blockage is sometimes from the buildup of plaque (deposits of fat-like substances) due to Atherosclerosis.

A heart attack also can be caused by a blood clot lodged in a coronary artery. Such an event is sometimes called a coronary thrombosis or coronary occlusion. If the blood supply is cut off severely or for a long time, muscle cells suffer irreversible injury and die. Disability or death can result, depending on how much heart muscle is damaged. In addition, a coronary artery may temporarily contract or go into spasm. When this happens, the artery narrows and blood flow to part of the heart muscle decreases or even stops. What causes a spasm is unclear--but it can occur in normal-appearing blood vessels as well as vessels partly blocked by Atherosclerosis. If a spasm is severe, a heart attack may result.

Heart Attack Symptoms/Warning Signs

IF YOU THINK YOU ARE HAVING A HEART ATTACK, CALL 911 OR YOUR EMERGENCY MEDICAL SYSTEM IMMEDIATELY.

According to the American Heart Association, the body will likely send one or more of the following warning signals of a heart attack:

• Uncomfortable pressure, fullness, squeezing or pain in the center of the chest that lasts more than a few minutes.
• Pain spreading to the shoulders, neck or arms.
  
• Chest discomfort with lightheadedness, fainting, sweating, nausea or shortness of breath.

How do I know if a heart attack has occurred?

The actual diagnosis of a heart attack must be made by a physician who has studied the results of several tests. The doctor will:

• Review your complete medical history.
• Give a physical examination.
• Use an electrocardiogram (EKG) to discover any abnormalities caused by damage to the heart.
• Sometimes use a blood test to detect abnormal levels of certain enzymes in the bloodstream.

See American Heart Association for more information on Heart Attack.