When one or more of the coronary arteries is obstructed or blocked - usually due to blood clot formation in the blood vessel - the blood cannot reach the heart muscle on the other side the blockage. Usually within 20 minutes of not receiving the oxygen-rich blood it needs, parts of the heart muscle stop functioning, thus leading to a heart attack. A heart attack - also called a myocardial infarction or MI - is the result of loss of function (pumping or contracting ability) of the damaged portion of the heart.

What are the symptoms of a heart attack?

People who experience a heart attack often feel they are being squeezed by a vice or a heavy weight has been placed on their chest. Others report a stabbing, knifelike or hot, burning sensation. The pain can last for as long as 30 minutes - or sometimes it may even last for hours. Changing the position of the body during a heart attack will not decrease or increase the amount of pain. Some patients experience no chest pain at all (this is called a "silent heart attack").

Some patients describe pain shooting down the arms (usually the left arm) with a tingling sensation in the wrists, hands, and fingers. Still other patients report feeling pain in the shoulders, neck, and jaw. Additional symptoms include indigestion or heartburn, nausea, vomiting, palpitations, cold sweats, weakness, dizziness, cough, fainting, dry mouth, and anxiety.

Men and women may generally experience the same symptoms during a heart attack. Women sometimes describe their chest pain differently. For men, chest pain is usually more localized, while women may say that their chest pain is more widely distributed.

Although many heart attack victims report some form of chest pain, people over age 75 and diabetics often do not feel chest pain and may only feel like they are having indigestion (heartburn) or shortness of breath. However, this is not a general rule. People under age 75 can also have silent heart attacks, which do not involve chest pain.

Heart attacks are a major cause of sudden death in adults. It is estimated that someone in the United States suffers a heart attack approximately every 30 seconds. Many people think that heart attacks are an old man's disease, but men and women are both affected. Of those who die from heart attacks, 48 percent are women. In fact, more women die from heart disease than from all forms of cancer combined.

What should I do if I think I'm having a heart attack?

If you are experiencing chest discomfort and any of the symptoms listed above, you or someone close to you should call 911 immediately. If you have symptoms but are not sure if you are having a heart attack, call your doctor immediately. There is a strong tendency to deny that you may be having a heart attack. Postponing or delaying medical treatment can cost you your life. Studies have shown that one out of three people die from a heart attack within the first few hours of experiencing chest pain. Getting to a hospital as quickly as possible is probably the single most important factor in surviving a heart attack.

The following are specific guidelines to follow if you think you are having a heart attack:

• People over age 75, diabetics, or people with a history of previous heart attack should seek immediate medical attention - even if they are only experiencing nausea, indigestion, or shortness of breath without chest pain.
• If your doctor has given you nitroglycerin tablets, put one under your tongue when the symptoms begin and repeat at five-minute intervals for a total of three doses. If the symptoms have not disappeared within 15 minutes, call 911 immediately.
• Do not take nitroglycerin tablets unless directed by a doctor. Taking nitroglycerin under the wrong circumstances may result in problems.
• If you think you are having a heart attack, chew one aspirin. If you are experiencing a heart attack it will be of benefit, but it will not cause harm if you are not.
• If you are with someone whose heart has stopped beating, call 911 immediately. Administer cardiopulmonary resuscitation (CPR) immediately.

What happens once I get to the hospital emergency room?

The goals of the hospital staff are to restore blood flow through your coronary arteries and to decrease the workload on your heart and prevent and treat complications. An IV (intravenous catheter) will be placed in a vein in order to administer fluids and medications. Even if blood levels of oxygen are normal, oxygen is generally administered to decrease the workload of the heart and make oxygen readily available to the body. A urinary catheter may be inserted to help monitor the input and output of fluid from the body.

Your doctor will use your previous medical history, physical examination, an electrocardiogram (ECG), and the level of specific enzymes in your blood to evaluate the severity of your condition and how best to prescribe treatment.

The doctors will ask you to describe the type of chest pain you may have experienced. They will also want to know whether you have had a heart attack in the past, if you have had earlier surgery, and if you take any medications. (It is extremely helpful if a family member knows about your medication and the dosages you are taking in case you are unable to tell the doctor.)