HEART ATTACK

A heart attack occurs when the flow of blood to the heart is blocked, most often by a build-up of fat, cholesterol and other substances, which form a plaque in the arteries that feed the heart (coronary arteries). The interrupted blood flow can damage or destroy part of the heart muscle.

A heart attack, also called a myocardial infarction, can be fatal, but treatment has improved dramatically over the years. It's crucial to call 911 or emergency medical help if you think you might be having a heart attack.
Common heart attack signs and symptoms include:

Pressure, tightness, pain, or a squeezing or aching sensation in your chest or arms that may spread to your neck, jaw or back
Nausea, indigestion, heartburn or abdominal pain
Shortness of breath
Cold sweat
Fatigue
Lightheadedness or sudden dizziness
Heart attack symptoms vary

Not all people who have heart attacks have the same symptoms or have the same severity of symptoms. Some people have mild pain; others have more severe pain. Some people have no symptoms, while for others, the first sign may be sudden cardiac arrest. However, the more signs and symptoms you have, the greater the likelihood you're having a heart attack.

Some heart attacks strike suddenly, but many people have warning signs and symptoms hours, days or weeks in advance. The earliest warning may be recurrent chest pain (angina) that's triggered by exertion and relieved by rest. Angina is caused by a temporary decrease in blood flow to the heart.

A heart attack differs from a condition in which your heart suddenly stops (sudden cardiac arrest, which occurs when an electrical disturbance disrupts your heart's pumping action and causes blood to stop flowing to the rest of your body). A heart attack can cause cardiac arrest, but it's not the only cause.

When to see a doctor

Act immediately. Some people wait too long because they don't recognize the important signs and symptoms. Take these steps:

Call for emergency medical help. If you 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 if there are no other options. Because your condition can worsen, driving yourself puts you and others at risk.

Take nitroglycerin, if prescribed to you by a doctor. Take it as instructed while awaiting emergency help.
Take aspirin, if recommended. Taking aspirin during a heart attack could reduce heart damage by helping to keep your blood from clotting.

Aspirin can interact with other medications, however, so don't take an aspirin unless your doctor or emergency medical personnel recommend it. Don't delay calling 911 to take an aspirin. Call for emergency help first.

What to do if you see someone having a heart attack

If you encounter someone who is unconscious, first call for emergency medical help. Then begin CPR to keep blood flowing. Push hard and fast on the person's chest ? about 100 compressions a minute. It's not necessary to check the person's airway or deliver rescue breaths unless you've been trained in CPR.
A heart attack occurs when one or more of your coronary arteries become blocked. Over time, a coronary artery can narrow from the buildup of various substances, including cholesterol (atherosclerosis). This condition, known as coronary artery disease, causes most heart attacks.

During a heart attack, one of these plaques can rupture and spill cholesterol and other substances into the bloodstream. A blood clot forms at the site of the rupture. If large enough, the clot can completely block the flow of blood through the coronary artery.

Another cause of a heart attack is a spasm of a coronary artery that shuts down blood flow to part of the heart muscle. Use of tobacco and of illicit drugs, such as cocaine, can cause a life-threatening spasm. A heart attack can also occur due to a tear in the heart artery (spontaneous coronary artery dissection).
Certain factors contribute to the unwanted buildup of fatty deposits (atherosclerosis) that narrows arteries throughout your body. You can improve or eliminate many of these risk factors to reduce your chances of having a first or subsequent heart attack.

Heart attack risk factors include:

Age. Men age 45 or older and women age 55 or older are more likely to have a heart attack than are younger men and women.
Tobacco. Smoking and long-term exposure to secondhand smoke increase the risk of a heart attack.
High blood pressure. Over time, high blood pressure can damage arteries that feed your heart by accelerating atherosclerosis. High blood pressure that occurs with obesity, smoking, high cholesterol or diabetes increases your risk even more.
High blood cholesterol or triglyceride levels. A high level of low-density lipoprotein (LDL) cholesterol (the "bad" cholesterol) is most likely to narrow arteries. A high level of triglycerides, a type of blood fat related to your diet, also ups your risk of heart attack. However, a high level of high-density lipoprotein (HDL) cholesterol (the "good" cholesterol) lowers your risk of heart attack.
Diabetes. Insulin, a hormone secreted by your pancreas, allows your body to use glucose, a form of sugar. Having diabetes ? not producing enough insulin or not responding to insulin properly ? causes your body's blood sugar levels to rise. Diabetes, especially uncontrolled, increases your risk of a heart attack.
Family history of heart attack. If your siblings, parents or grandparents have had early heart attacks (by age 55 for male relatives and by age 65 for female relatives), you may be at increased risk.
Lack of physical activity. An inactive lifestyle contributes to high blood cholesterol levels and obesity. People who get regular aerobic exercise have better cardiovascular fitness, which decreases their overall risk of heart attack. Exercise is also beneficial in lowering high blood pressure.
Obesity. Obesity is associated with high blood cholesterol levels, high triglyceride levels, high blood pressure and diabetes. Losing just 10 percent of your body weight can lower this risk, however.
Stress. You may respond to stress in ways that can increase your risk of a heart attack.
Illegal drug use. Using stimulant drugs, such as cocaine or amphetamines, can trigger a spasm of your coronary arteries that can cause a heart attack.
A history of preeclampsia. This condition causes high blood pressure during pregnancy and increases the lifetime risk of heart disease.
A history of an autoimmune condition, such as rheumatoid arthritis or lupus. Conditions such as rheumatoid arthritis, lupus and other autoimmune conditions can increase your risk of having a heart attack.
Complications

Heart attack complications are often related to the damage done to your heart during a heart attack. This damage can lead to the following conditions:

Abnormal heart rhythms (arrhythmias). If your heart muscle is damaged from a heart attack, electrical "short circuits" can develop, resulting in abnormal heart rhythms, some of which can be serious, even fatal.
Heart failure. The amount of damaged tissue in your heart may be so great that the remaining heart muscle can't do an adequate job of pumping blood out of your heart. Heart failure may be a temporary problem that goes away after your heart, which has been stunned by a heart attack, recovers. However, it can also be a chronic condition resulting from extensive and permanent damage to your heart following your heart attack.
Heart rupture. Areas of heart muscle weakened by a heart attack can rupture, leaving a hole in part of the heart. This rupture is often fatal.
Valve problems. Heart valves damaged during a heart attack may develop severe, life-threatening leakage problems.
TESTS & DIAGNOSIS
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Ideally, your doctor should screen you during regular physical exams for risk factors that can lead to a heart attack.

If you're in an emergency setting for symptoms of a heart attack, you'll be asked to describe your symptoms and have your blood pressure, pulse and temperature checked. You'll be hooked up to a heart monitor and will almost immediately have tests to see if you're having a heart attack.

Tests will help check if your signs and symptoms, such as chest pain, indicate a heart attack or another condition. These tests include:

Electrocardiogram (ECG). This first test done to diagnose a heart attack 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 of your heart and its blood vessels and to look for fluid in your lungs.
Echocardiogram. During this test, sound waves directed at your heart from a wand like device (transducer) held on your chest bounce off your heart and are 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). 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 or groin, to the arteries in your heart. The dye makes the arteries visible on X-ray, revealing areas of blockage.
Exercise stress test. In the days or weeks after 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.

Your doctor may also order a nuclear stress test, which is similar to an exercise stress test, but uses an injected dye and special imaging techniques to produce detailed images of your heart while you're exercising. These tests can help determine your long-term treatment.

Cardiac computerized tomography (CT) or magnetic resonance imaging (MRI). These tests can be used to diagnose heart problems, including the extent of damage from heart attacks. In a cardiac CT scan, you lie on a table inside a doughnut-shaped machine. An X-ray tube inside the machine rotates around your body and collects images of your heart and chest.

In a cardiac MRI, you lie on a table inside a long tubelike machine that produces a magnetic field. The magnetic field aligns atomic particles in some of your cells. When radio waves are broadcast toward these aligned particles, they produce signals that vary according to the type of tissue they are. The signals create images of your heart.