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.
Tests 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 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.
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 wandlike 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.
Treatments and drugs
Heart attack treatment at a hospital
With each passing minute after a heart attack, more heart tissue loses oxygen and deteriorates or dies. The main way to prevent heart damage is to restore blood flow quickly.
Medications given to treat a heart attack include:
- Aspirin. The 911 operator may instruct you to take aspirin, or emergency medical personnel may give you aspirin immediately. Aspirin reduces blood clotting, thus helping maintain blood flow through a narrowed artery.
- Thrombolytics. These drugs, also called clotbusters, help dissolve a blood clot that's blocking blood flow to your heart. The earlier you receive a thrombolytic drug after a heart attack, the greater the chance you'll survive and with less heart damage.
- Antiplatelet agents. Emergency room doctors may give you other drugs to help prevent new clots and keep existing clots from getting larger. These include medications, such as clopidogrel (Plavix) and others, called platelet aggregation inhibitors.
- 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 clots. Heparin is given intravenously or by an injection under your skin.
- Pain relievers. You may receive a pain reliever, such as morphine, to ease your discomfort.
- Nitroglycerin. This medication, used to treat chest pain (angina), can help improve blood flow to the heart by widening (dilating) the blood vessels.
- 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.
- ACE inhibitors. These drugs lower blood pressure and reduce stress on the heart.
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. Doctors insert a long, thin tube (catheter) that's passed through an artery, usually in your leg or groin, to a blocked artery in your heart. If you've had a heart attack, this procedure is often done immediately after a cardiac catheterization, a procedure used to locate blockages.
This catheter is equipped with a special balloon that, once in position, is briefly inflated to open a blocked coronary artery. 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, your doctor may opt to place a stent coated with a slow-releasing medication to help keep your artery open.
- Coronary artery bypass surgery. In some cases, doctors may perform emergency bypass surgery at the time of a heart attack. If possible, your doctor may suggest that you have bypass surgery after your heart has had time — about three to seven days — to recover from your heart attack.
Bypass surgery involves sewing veins or arteries in place beyond a blocked or narrowed coronary artery, allowing blood flow to the heart to bypass the narrowed section.
Once blood flow to your heart is restored and your condition is stable, you're likely to remain in the hospital for several days.
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