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What is a heart attack?

A heart attack is injury to heart muscle due to a loss of blood supply. It usually occurs when a blood clot blocks the flow of blood through a coronary artery — a blood vessel that feeds blood to a part of the heart muscle. Interrupted blood flow to your heart can damage or destroy a part of the heart muscle. It can also be fatal.

Each year more than a million Americans experience a heart attack. Years ago, a heart attack was often fatal. But today, thanks to better awareness of signs and symptoms and improved treatments, the vast majority of people who have a heart attack survive.

Your overall lifestyle — what you eat, how often you exercise and the way you deal with stress — plays a role in how well you recover from a heart attack. In addition, a healthy lifestyle can help you prevent a first or subsequent heart attack by controlling risk factors that contribute to the narrowing of arteries to your heart.

Heart Center

Signs and symptoms

Heart attacks have many variable signs and symptoms. Not all people who have heart attacks experience the same ones or experience them to the same degree.

For example, heart attack symptoms in women, in older adults and in people with diabetes tend to be less pronounced. Some people have no symptoms at all. Still, the more signs and symptoms you have, the higher the likelihood that you may be experiencing a heart attack.

Warning signs and symptoms of a heart attack include: A heart attack usually strikes suddenly. It can occur anytime — at work or play, while you're resting, or while you’re in motion. However, about half of all heart attack victims have warning signs and symptoms hours, days or weeks in advance. The earliest predictor of an attack may be recurrent chest pain (angina) that’s triggered by exertion and relieved by rest. Angina is caused by temporary, insufficient blood flow to the heart. The medical term for insufficient blood flow to the heart is cardiac ischemia.

Chest pain
Cardiac ischemia

Causes

Your heart — a muscular pump in your chest — beats approximately once a second. During a day, your heart pumps about 2,000 gallons of blood through your circulatory system.

Your circulatory system includes arteries and veins. Veins bring oxygen-poor blood back to your heart. Arteries deliver oxygen-rich blood to all of the tissues of your body — including your heart muscle.

A heart attack occurs when one or more of the tiny arteries supplying your heart with oxygen-rich blood (coronary arteries) become blocked. These arteries are called coronary arteries because they encircle the top portion of your heart like a crown. Blockage is usually due to a blood clot that forms suddenly where a coronary artery has narrowed over the years by a buildup of cholesterol and other deposits.


This buildup of cholesterol and other deposits — collectively known as plaques — in arteries throughout the body is called atherosclerosis. When the coronary arteries narrow due to atherosclerosis, the condition is known as coronary artery disease.

Coronary artery disease is a major underlying cause of heart attacks. Factors that increase your risk of narrowed coronary arteries — and, thus, a heart attack — include family history of heart disease, a high level of low-density lipoprotein (LDL) cholesterol (the "bad" cholesterol), high blood pressure, smoking, obesity and physical inactivity.

Rarely, a heart attack can occur when a blood clot from inside a diseased heart breaks loose and lodges in a healthy or narrowed coronary artery. Another uncommon cause of a heart attack is a spasm of a coronary artery that shuts down blood flow to part of the heart muscle. Drugs such as cocaine can cause such a life-threatening spasm.

The technical term for a heart attack is myocardial infarction. Myo refers to "muscle;" cardio refers to "heart;" infarct refers to "death of tissue from lack of oxygen." Like any muscle, the heart needs a steady supply of blood, or the tissue will be damaged or begin to die. Without blood, heart cells are injured, causing pain or pressure. If blood flow isn't restored, heart cells can die and scar tissue can form, replacing working heart tissue. If damage occurs to too great an area of heart muscle, a heart attack can be fatal.

A heart attack is not a static one-time event. It's a dynamic process that typically evolves over 4 to 6 hours. With each passing minute, more heart tissue is deprived of blood and deteriorates or dies. However, if blood flow can be restored in time, damage to the heart can be limited or prevented.

Coronary artery disease

Risk factors

Certain factors, called coronary risk factors, increase your risk of a heart attack. These factors contribute to the unwanted buildup of deposits (atherosclerosis) that narrows arteries throughout your body, including arteries to your heart. Coronary risk factors include: You can modify or eliminate many of these risk factors to reduce your chances of having a first or second heart attack. However, you can’t change some risk factors, including heredity, race (heart attack risk is higher in blacks) and sex. Men are generally at greater risk than women are of heart attacks. However, the risk for women increases after menopause.

High blood pressure
High Blood Cholesterol
Obesity
Diabetes
Heart-healthy families: Knocking down the building blocks of heart attack
Menopause

When to seek medical advice

During a heart attack, many people waste precious minutes because they don't recognize signs and symptoms — or they deny them. Many people also delay calling for help because they're afraid to risk the embarrassment of a false alarm.

However, one of the most important things you can do to survive a heart attack is to recognize what's happening and to take immediate action. Of the people who die of heart attacks, most die within the first hour after the onset of signs and symptoms. Don't waste time — minutes matter!

Seek emergency medical treatment if you think you or another person may be experiencing a heart attack. An ambulance crew can begin treatment, and the sooner you get to a hospital, the more that can be done to limit the amount of damage done to your heart during a heart attack. Fast action could save your life.

Screening and diagnosis

Ideally, your doctor should screen you during regular physical exams for risk factors that can lead to a heart attack.

If you're having a heart attack or suspect you're having one, screening and diagnosis will likely happen in another setting — an emergency room. Once there, you'll probably be asked to describe your symptoms and will have your blood pressure, pulse and temperature checked. Your doctor will listen to your heart and lung sounds with a stethoscope. You'll be asked about your health history and the history of heart disease in your family. Emergency room doctors may also want to conduct tests to determine whether your signs and symptoms, such as chest pain, signal a heart attack or another condition. These tests may include: If you've had a heart attack or one is occurring, doctors will take immediate steps to treat your condition. You may also undergo these additional tests: In the days or weeks following your heart attack, you may also undergo a stress test. Stress tests measure how your heart and blood vessels respond to exertion. You may walk on a treadmill or pedal a stationary bike while hooked to an ECG machine. Or you may receive a drug intravenously that stimulates your heart in a way similar to exercise. Stress tests help doctors diagnose coronary artery disease, which can cause chest pain and may underlie a recent or future heart attack.

Blood tests: Seeking clues about your heart's health
Electrocardiogram
ECG: Can it detect silent heart attacks?
Chest X-rays: Helping detect heart and lung conditions
Nuclear stress test
Echocardiogram

Complications

At the very least, a heart attack can cause pain and discomfort. At the very most, a heart attack can cause death. Complications are often related to the damage sustained by your heart during a heart attack. This damage can lead to the following conditions:
Heart arrhythmias
Congestive heart failure

Treatment

During a heart attack, act immediately. Take these steps: If you encounter someone who is unconscious from a presumed heart attack, call for emergency medical help and begin mouth-to-mouth breathing and chest compression or cardiopulmonary resuscitation (CPR). This helps deliver oxygen to the body and brain. If you're not trained, the emergency line operator can instruct you in CPR until help arrives.

In the initial minutes, a heart attack can also trigger ventricular fibrillation. This unstable heart rhythm produces an ineffective heartbeat, and the heart quivers uselessly. Without immediate treatment, ventricular fibrillation leads to sudden death. The wide use of automatic external defibrillators (AEDs) that shock the heart back into a normal rhythm can provide emergency treatment before a person suffering a heart attack reaches the hospital.

Most ambulance teams carry portable defibrillators. Many police and fire rescue units also carry defibrillators and may respond before an ambulance. AEDs are easy to operate and are also increasingly available in commercial airplanes and public places.

Once you reach a hospital emergency room and it's clear you're having a heart attack, you may be treated with medications, undergo a surgical procedure or both — depending on the severity of your condition and the amount of damage your heart may have sustained.

Aspirin: From pain relief to preventive medicine
Cardiopulmonary resuscitation (CPR)

Medications
With each passing minute of a heart attack, more tissue is deprived of oxygen and deteriorates or dies. The main way to prevent progressive damage is to restore blood flow quickly. Doctors may give you aspirin in the emergency room. Aspirin inhibits blood clotting, which helps maintain blood flow through a narrowed artery. But, again, if you think you're having a heart attack, take one regular strength aspirin and chew it to speed absorption on your way to the emergency room.

Initial treatment of a heart attack in the emergency room may also involve prescription medications, typically given through a vein in your arm (intravenously), such as: Many medications improve survival and help heal a heart during and after a heart attack. Your doctors will determine which medications are best for you. You may receive different drugs depending on the cause of your heart attack and the overall health of your heart.

Surgical and other procedures
In addition to medications, you may undergo one of the following procedures to treat a heart attack: Once blood flow to your heart is restored and your condition is stable following a heart attack, you may be hospitalized for observation. Because physical exertion and emotional upset place stress on your heart, be sure to rest and not have too many visitors. Visitors are usually limited to family members and close friends.

Coronary angioplasty: Opening clogged arteries

Rehabilitation
The goal of emergency treatment of a heart attack is to restore blood flow and save heart tissue. The purpose of subsequent treatment is to promote healing of your heart and prevent another heart attack.

Cardiac rehabilitation programs begin while you're in the hospital and, depending on the severity of your attack, continue for weeks to months after you return home. Cardiac rehabilitation programs generally focus on three main areas — medications, lifestyle changes and emotional issues.

Cardiac rehabilitation: Getting your heart back in gear

Prevention

It's never too late to take steps to prevent a heart attack — even if you've already had one before. Drug therapy has become an increasingly important part of reducing the risk of a second heart attack and helping a damaged heart function better. Lifestyle factors also play a critical role in heart attack prevention and recovery.

Medications
Doctors typically prescribe drug therapy for people who've had a heart attack or who are at high risk of having one. Medications that help the heart function more effectively or reduce heart attack risk may include: Lifestyle
How you live your life can largely affect the health of your heart. Taking the following steps can help you not only prevent but also recover from a heart attack:
Heart-healthy eating
Stop Smoking Program
Stress Management Program
In search of a better blood pressure: Editor's note

Coping skills

Having a heart attack is a scary experience. Even if your doctor says you're OK, you may still be scared. How will this affect your life? Will you be able to get back to work or resume activities you enjoy? Even more frightening — will it happen again?

Fear is just one of the many emotions you and your family must deal with. Other emotions that can be particularly difficult to cope with after a heart attack may include: These feelings are common, and openly discussing them with your doctor, a family member or a friend may help you better cope. You need to take care of yourself mentally as well as physically after a heart attack.

Many people worry that sex after a heart attack will be too strenuous on their heart. However, most people can safely return to sexual activity by the second week after a heart attack or heart operation. Each person has a different timeline, depending on his or her level of physical comfort, psychological readiness and previous sexual activity.

The demands sexual intercourse places on your heart approximate those of taking a brisk walk, scrubbing a floor, or climbing one or two flights of stairs. In a way, sexual activity parallels any other physical exertion — your heart rate, breathing rate and blood pressure level increase. So proceed sensibly, with caution but without fear. As your confidence in the health of your heart grows, you'll likely be able to resume your normal sexual patterns.

Some heart medications, such as beta blockers, may affect sexual function. However, sexual dysfunction following a heart attack is more often due to depression or anxiety than to medications. If you're having problems with sexual dysfunction, talk to your doctor. He or she may be able to help you pinpoint the problem and seek the appropriate treatment.

You and your family may have a lot of questions and concerns following your heart attack. If so, it might be helpful to talk to others who are experiencing some of the same things as you and your family. Many cardiac rehabilitation programs offer counseling services and support groups for heart attack survivors.

Surviving a heart attack doesn't mean that life as you know it is over. On the contrary, most people lead full, active lives after a heart attack. But it may mean making some positive changes in your daily habits, being patient as you recover and adopting a can-do attitude.

Depression

May 15, 2003