A heart attack most often occurs when one of the three major blood vessels feeding the heart becomes blocked, cutting off the supply of oxygen-rich blood to the heart muscle. Without oxygen, that part of the heart eventually dies. If the rest of the heart is still healthy, it will continue pumping, giving the injured muscle time to heal and regain some of its strength. However, once heart muscle has died, the heart becomes weakened, heart valves may be damaged, and the person may develop an irregular heartbeat. If damage to the heart is severe, a heart attack can be fatal.

Heart attack is the number one killer of adults in the World. It strikes 4,100 people every day, causing 600,000 deaths each year. The warning signs can be subtle and sometimes difficult to identify. In fact, many people don't recognize the symptoms, even when they are in the middle of a major heart attack. This is critical, because the amount of time that passes from when a heart attack begins to when you receive treatment can mean the difference between life and death.

What causes a heart attack?

The most common cause of a heart attack is a condition called "atherosclerosis." This is the narrowing of the blood vessels that takes place when cholesterol "plaque," a fatty substance, builds up in them over time. A high-fat diet, cigarette smoking, hypertension, and family history all contribute to atherosclerosis, which forces the heart to pump harder and harder to push blood through the narrowed vessels. Sometimes, the plaque, or a clot of blood that forms on the plaque, may completely block the artery. This may be the beginning of a heart attack.

A heart attack may be triggered by strenuous exercise, such as shoveling snow, or by extreme emotional stress, which can cause a sudden increase in blood pressure. Sometimes it can strike without warning.

How to know when you are having a heart attack?

If you are having a heart attack, you will typically experience a condition known as angina-a painful tightness, burning, or squeezing in the chest. If you have angina, report it immediately to your doctor. He or she can prescribe nitroglycerin tablets, which temporarily widen the blood vessel, allowing more blood to reach the heart muscle. Other typical warning signs and symptoms are chest pain or tightness that spreads to the left arm or shoulder, or even to the abdomen or jaw; shortness of breath, sweating, nausea, or vomiting; and weakness, dizziness, or lightheadedness.

What to do if you think you are having a heart attack?

Sit or lie down. If symptoms persist for two minutes, call 911 or the emergency number in your area, and say you think you are having a heart attack. Do not drive yourself to the hospital, and do not delay getting treatment, even if you are not sure you are having a heart attack. Delay can cause permanent damage to your heart muscle, and could be fatal.

If you have nitroglycerin tablets with you, take up to three pills, one every five minutes, for as long as symptoms last. It is also recommended that you take a single tablet of aspirin. If your breathing or pulse stops, someone trained in cardiopulmonary resuscitation (CPR) should perform it immediately, if possible. When you arrive at the hospital emergency room, you or whoever is with you should make it clear that you may be having a heart attack.

Diagnosing a heart attack – Dr Ashwani Mehta

At the hospital, you will be given a series of tests. A heart monitor shows your pulse as well as abnormal heart rates or rhythms; electrocardiogram (ECG) measures and records the electrical activity of your heart; your blood oxygen level can be monitored by a sensor attached to your finger or ear; blood tests determine whether the heart muscle has been damaged; a chest x-ray can show abnormal heart size and signs of heart failure; a stress test shows whether the heart is getting enough blood and how well it tolerates exercise; and a scanning test called Doppler ultrasound (echocardiogram) examines your heart vales, muscles, and blood flow and determines how well your heart is pumping.

Treating a heart attack - the sooner the better

You may be given medication to help dissolve a blood clot that could be blocking your artery. If your heartbeat is abnormal, the doctor may need to stabilize it. If your heart has stopped, doctors will compress your chest rhythmically, to keep it pumping until your heartbeat returns. Later, you may be given blood-thinning medications to help prevent more clots from forming.

Your doctor may also perform a "coronary angiogram," which can determine the extent of the clot and whether a surgical procedure may be necessary.

When your condition is stable and you are ready to leave the hospital, your doctor may have you wear a small ECG recorder, called a Holter monitor, for 24 hours. This will track whether your heartbeat is irregular during certain activities.

Follow-up care, rehabilitation, and recovery

After a heart attack, it is important to take it easy at first. You will then probably begin a rehabilitation program, which involves a gradual and closely monitored exercise program, as well as education about diet and other ways to improve your health and prevent future heart attacks. It is important to follow the treatment plan prescribed by your doctor. Carry any medication that your doctor prescribes with you and know how to take it. If you smoke, stop. Eat healthy foods that are low in fat and sodium. Lose weight if you need to and exercise regularly, according to your doctor's instructions. Make sure to keep follow-up appointments with your doctor and to call 911 if you experience any chest pain.

Supported as an educational service by Novartis Pharmaceuticals Corporation. This information is not intended for use as medical advice. You should discuss this information with your doctor.