Diseases & Conditions

Heart attack

A heart attack 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.

Years ago, a heart attack was often fatal. Thanks to better awareness of heart attack signs and symptoms and improved treatments, most people who have a heart attack now survive.

Your overall lifestyle — what you eat, how often you exercise and the way you deal with stress — plays a role in your recovery 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 the coronary arteries that supply blood to your heart.

Common signs and symptoms of a heart attack include:

• Pressure, fullness or a squeezing pain in the center of your chest that lasts for more than a few minutes
• Pain extending beyond your chest to your shoulder, arm, back, or even to your teeth and jaw
• Increasing episodes of chest pain
• Prolonged pain in the upper abdomen
• Shortness of breath
• Sweating
• Impending sense of doom
• Fainting
• Nausea and vomiting

Signs and symptoms of a heart attack in women may be different or less noticeable than heart attack symptoms in men. In addition to the symptoms above, heart attack symptoms in women can include:

• Abdominal pain or "heartburn"
• Clammy skin
• Lightheadedness or dizziness
• Unusual or unexplained fatigue

Not all people who have heart attacks experience the same ones or experience them to the same degree. Many heart attacks aren't as dramatic as the ones you've seen on TV. Some people have no symptoms at all. Still, the more signs and symptoms you have, the greater the likelihood that you may be having a heart attack.

A heart attack can occur anytime — at work or play, while you're resting, or while you're in motion. Some heart attacks strike suddenly, but many people who experience a heart attack 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, also known as "cardiac ischemia."

The medical 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. 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. The lack of blood flow to the heart also may trigger irregular heart rhythms that can be fatal.

A heart attack occurs when one or more of the arteries supplying your heart with oxygen-rich blood become blocked. These arteries are called coronary arteries and encircle your heart like a crown. Over time, a coronary artery can become narrowed from the buildup of cholesterol. This buildup — collectively known as plaques — in arteries throughout the body is called atherosclerosis.

During a heart attack, one of these plaques can rupture and a blood clot forms on the site of the rupture. If the clot is large enough, it can block the flow of blood through the artery. When your coronary arteries have narrowed due to atherosclerosis, the condition is known as coronary artery disease. Coronary artery disease is the major underlying cause of heart attacks.

An 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.

A heart attack is the end of a process that typically evolves over several 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.

During a heart attack, some people waste precious minutes because they don't recognize the important signs and symptoms — or they deny them. Some 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 increase your survival after a heart attack is to recognize what's happening and take immediate action. Of the people who die of heart attacks, about half die within the first hour after the onset of signs and symptoms.

Don't "tough out" the symptoms of a heart attack, such as pressure or pain in your chest, for more than five minutes. Call 911 or other emergency medical services for help. If you don't have access to emergency medical services, have someone drive you to the nearest hospital, such as a neighbor or friend. Drive yourself only as a last resort, if there are absolutely no other options. Driving yourself puts you and others at risk if your condition suddenly worsens.

If it turns out you weren't having a heart attack, doctors may be able to pinpoint the cause of your signs and symptoms and treat them.

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 an emergency setting. You'll be asked to describe your symptoms and will have your blood pressure, pulse and temperature checked. You'll be hooked up to a heart monitor and will almost immediately start to have tests done to determine if you are indeed having a heart attack. The medical staff 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. The tests your doctors order will help determine whether your signs and symptoms, such as chest pain, signal a heart attack or another condition. These tests include:

• Electrocardiogram (ECG). This is the first test done to diagnose a heart attack. It's often done while you are being asked questions about your symptoms. This test records the electrical activity of your heart via electrodes attached to your skin. Impulses are recorded as "waves" displayed on a monitor or printed on paper. Because injured heart muscle doesn't conduct electrical impulses normally, the ECG may show that a heart attack has occurred or is in progress.
• Blood tests. Certain heart enzymes slowly leak out into your blood if your heart has been damaged by a heart attack. Emergency room doctors will take samples of your blood to test for the presence of these enzymes.

Additional tests
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:

• Chest X-ray. An X-ray image of your chest allows your doctor to check the size and shape of your heart and its blood vessels.
• Nuclear scan. This test helps identify blood flow problems to your heart. Small amounts of radioactive material, such as thallium, are injected into your bloodstream. Special cameras can detect the radioactive material as it flows through your heart and lungs. Areas of reduced blood flow to the heart muscle — through which less of the radioactive material flows — appear as dark spots on the scan.
• Echocardiogram. This test uses sound waves to produce an image of your heart. During an echocardiogram, sound waves are directed at your heart from a transducer, a wand-like device, held on your chest. The sound waves bounce off your heart and are reflected back through your chest wall and processed electronically to provide video images of your heart. An echocardiogram can help identify whether an area of your heart has been damaged by a heart attack and isn't pumping normally or at peak capacity.
• Coronary catheterization (angiogram). This test can show if your coronary arteries are narrowed or blocked. A liquid dye is injected into the arteries of your heart through a long, thin tube (catheter) that's fed through an artery, usually in your leg, to the arteries in your heart. As the dye fills your arteries, the arteries become visible on X-ray, revealing areas of blockage. Additionally, while the catheter is in position, your doctor may treat the blockage by performing an angioplasty, also known as coronary artery balloon dilation, balloon angioplasty and percutaneous coronary intervention. Angioplasty uses tiny balloons threaded through a blood vessel and into a coronary artery to widen the blocked area. In most cases, a mesh tube (stent) is also placed inside the artery to hold it open more widely and prevent re-narrowing in the future.

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 attached to an ECG machine. Or you may receive a drug intravenously that stimulates your heart similar to exercise. Stress tests help doctors determine the best long-term treatment for you.

During a heart attack, act immediately. Take these steps:

• Call for emergency medical help. If you even suspect you're having a heart attack, don't hesitate. Immediately call 911 or your local emergency number. If you don't have access to emergency medical services, have someone drive you to the nearest hospital. Drive yourself only as a last resort, if there are absolutely no other options. Driving yourself puts you and others at risk if your condition suddenly worsens.
• Take nitroglycerin. If your doctor has prescribed nitroglycerin, take as instructed while awaiting the arrival of emergency medical personnel.

If you encounter someone who is unconscious from a presumed heart attack, call for emergency medical help and, if you have received training in emergency procedures, begin cardiopulmonary resuscitation (CPR). This helps deliver oxygen to the body and brain. If you're not trained in emergency procedures, doctors recommend skipping mouth-to-mouth rescue breathing and proceeding directly to chest compression. Do chest compressions at a rate of 100 a minute.

In the initial minutes, a heart attack can also trigger ventricular fibrillation, a condition in which the heart quivers uselessly. Without immediate treatment, ventricular fibrillation leads to sudden death. The timely use of an automatic external defibrillator (AED) that shocks the heart back into a normal rhythm can provide emergency treatment before a person suffering a heart attack reaches the hospital.

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

Medications
With each passing minute after 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.

Medications given to treat a heart attack include:

• Aspirin. You may be given aspirin by emergency medical personnel soon after they arrive or as soon as you get to the hospital. Aspirin inhibits blood clotting, thus helping maintain blood flow through a narrowed artery. Take an aspirin yourself while waiting for help to arrive only if your doctor has previously recommended that you do so if you have symptoms of a heart attack.
• Thrombolytics. These drugs, also called clot-busters, help dissolve a blood clot that's blocking blood flow to your heart. The earlier you receive a thrombolytic drug following a heart attack, the greater the chance you will survive and lessen the damage to your heart.
• Superaspirins. Doctors in the emergency room may give you other drugs which are somewhat similar to aspirin to help prevent new clots from forming. These include medications such as clopidogrel (Plavix) and others called platelet IIb/IIIa receptor blockers.
• Other blood-thinning medications. You'll likely be given other medications, such as heparin, to make your blood less "sticky" and less likely to form more dangerous clots. Heparin is given intravenously or by an injection under your skin and is usually used during the first few days after a heart attack.
• Pain relievers. If your chest pain or associated pain is great, you may receive a pain reliever, such as morphine, to alleviate your discomfort.
• Nitroglycerin. This medication, used to treat chest pain (angina), temporarily opens arterial blood vessels, improving blood flow to and from your heart.
• Beta blockers. These medications help relax your heart muscle, slow your heartbeat and decrease blood pressure making your heart's job easier. Beta blockers can limit the amount of heart muscle damage and prevent future heart attacks.
• Cholesterol-lowering medications. Examples include statins, niacin, fibrates and bile acid sequestrants. These drugs help lower levels of unwanted blood cholesterol and may be helpful if given soon after a heart attack to improve survival.

Surgical and other procedures
In addition to medications, you may undergo one of the following procedures to treat your heart attack:

• Coronary angioplasty and stenting. Emergency angioplasty opens blocked coronary arteries, letting blood flow more freely to your heart. Doctors insert a long, thin tube (catheter) that's passed through an artery, usually in your leg, to a blocked artery in your heart. This catheter is equipped with a special balloon tip. Once in position, the balloon tip is briefly inflated to open up a blocked coronary artery. At the same time, a metal mesh stent may be inserted into the artery to keep it open long term, restoring blood flow to the heart. Depending on your condition, you doctor may opt to place a stent coated with a slow-releasing medication to help keep your artery open.

  Coronary angioplasty is done at the same time as a coronary catheterization (angiogram), a procedure that doctors do first to locate narrowed arteries to the heart. When getting an angioplasty for heart attack treatment, the sooner the better. If an angioplasty is performed days or weeks after you've been stabilized with a completely blocked artery, there may not be any benefit.

• Coronary artery bypass surgery. In rare cases, doctors may perform emergency bypass surgery at the time of a heart attack. Bypass surgery involves sewing veins or arteries in place at a site beyond a blocked or narrowed coronary artery (bypassing the narrowed section), restoring blood flow to the heart. Or your doctor may suggest that you have this procedure after your heart has had time to recover from your heart attack.

Once blood flow to your heart is restored and your condition is stable following your heart attack, you may be hospitalized for observation. Because physical exertion and emotional upset place stress on your heart, be sure to rest. Visitors are usually limited to family members and close friends.

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.

Some hospitals offer cardiac rehabilitation programs that may start 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.