• Heart Attack

    (Acute Myocardial Infarction [AMI]; Myocardial Infarction [MI]; ST-Segment-Elevation MI [STEMI]; Transmural Myocardial infarction)

    Definition

    A heart attack is the blockage of blood flow to an area of the heart. The heart tissue becomes damaged or dies within a short time after blood flow is stopped. If a large or vital area is affected the damage may stop the heart from working.
    Heart Attack
    Heart Attack
    Copyright © Nucleus Medical Media, Inc.

    Causes

    The coronary arteries deliver oxygen-rich blood to the heart muscle. A heart attacks occurs when blood flow is interrupted in these arteries because of one or more of the following:
      Narrowing of the coronary arteries due to:
      • Thickening of the artery walls (common aging process)
      • Build up of fatty plaques inside the arteries
      • Spasm of the coronary arteries
      • Development of a blood clot in the arteries
    • Embolism, blood clot, that travels to the heart and blocks off smaller coronary arteries
    The severity of the heart attack will depend on how much of the heart tissue was affected and how long the blockage lasted. The amount of heart tissue that is affected will depend on which artery is blocked. There are two main coronary arteries that gradually split down into smaller branches of arteries. If the blockage occurs in the larger arteries it will affect a larger area of the heart. If the blockage occurs further down in the smaller vessels it affects a smaller area of the heart.

    Risk Factors

    The risk of heart attack is greater in males and older adults.
    Factors that affect the health of your blood vessels and increase your chance of developing a heart attack include:

    Symptoms

    Symptoms can vary but common symptoms include:
      Squeezing, heavy chest pain behind breastbone, that usually comes on quickly especially with:
      • Exercise or exertion
      • Emotional stress
      • Cold weather
      • A large meal
    • Pain in the left shoulder, left arm, or jaw
    • Shortness of breath
    • Sweating, clammy skin
    • Nausea
    • Weakness
    • Loss of consciousness
    • Anxiety , especially feeling a sense of doom or panic without apparent reason
    Unusual symptoms of heart attack—may occur more frequently in women:
    • Stomach pain
    • Back and shoulder pain
    • Confusion
    • Fainting
    If you think you may be having a heart attack, call for emergency medical services right away.

    Diagnosis

    If the doctor suspects a heart attack it may be confirmed with:
      EKG—records the electrical activity of the heart and can show if a heart attack has happened or may be happening. It can also help determine if the heart attack is:
      • STEMI—suggests total blockage of artery and more serious type of heart attack.
      • NSTEMI—suggests partial blockage of artery
    • Blood tests—certain markers in the blood will appear or increase if a heart attack has occurred. These markers can also indicate how much damage was done to the heart muscle.
    • Echocardiogram—an imaging test to examine the size, shape, function, and motion of the heart
    • Coronary angiography—a wire is passed through blood vessels to look for any blockages or damage to the coronary arteries.
    Further testing may be done to look for any damage or changes to the heart. Test will be based on your specific needs but may include:
    • Stress test —Records the heart's electrical activity under increased physical stress, usually done days or weeks after the heart attack.
    • Electron-beam computed tomography (EBCT)—to make detailed pictures of the heart, coronary arteries, and surrounding structures.

    Treatment

    The first goal of treatment is to improve blood flow and get oxygen to your heart as quick as possible. Treatment includes:
    • Aspirin and other antiplatelet agents—will decrease clotting in the blood to help it flow smoother.
    • Oxygen—inhaling more oxygen will increase the amount of oxygen in the blood for the heart
    • Nitrate medications—these medications can help the blood vessels open up and allow better blood flow.
    • Pain-relieving medication
    • Beta-blockers and/or angiotensin-converting enzyme (ACE) inhibitor medications—to decrease the workload on the heart
    • Anti-anxiety medication
    • Cholesterol-lowering medications such as statin drugs—may play an important role in decreasing chance of another heart attack or stroke.

    Removing Blockages

    If a blood clot is present, medications may be given to try to break up the clot. The sooner these medications are delivered the better the outcome will be. Ideally, the medications are delivered within the first 6 hours after symptoms appear.
    Other blockages, blood clots that don't respond to medication or plaque build up, may need to be surgically managed. The procedure may need to be done immediately for severe blockages or delayed for a few days if there is adequate blood flow. Surgical options include:
    • Balloon angioplasty—a wire is passed through blood vessels and a device is used to open up the blocked artery. A stent may also be placed in the blood vessel to help keep it open.
    • Coronary artery bypass grafting (CABG)—an open surgery that uses a section of blood vessel from another part of the body to create a path around the blocked area.

    Recovery

    Cardiac rehabilitation can help during recovery after a heart attack. It may include monitoring during physical activity in the first few weeks of recovery and education on healthful nutrition and lifestyle changes.
    A heart attack can be a major life event. It is common for people to experience depression after having a heart attack. Therapy and medication can help manage these challenges.

    Prevention

    Many lifestyle habits influence the health of the blood vessels and heart. Healthy heart habits include:
    Small daily doses of aspirin may help some people decrease their risk of aspirin. Aspirin for heart protection should only be done with a doctor's supervision since aspirin can cause complications like bleeding in the stomach or intestines. Aspirin may also interact with other medications like pain medications.

    RESOURCES

    American Heart Association http://www.heart.org

    National Stroke Association http://www.stroke.org

    CANADIAN RESOURCES

    Heart and Stroke Foundation of Canada http://www.heartandstroke.ca

    The College of Family Physicians of Canada http://www.cfpc.ca

    References

    About heart attacks. American Heart Association website. Available at: http://www.heart.org/HEARTORG/Conditions/HeartAttack/AboutHeartAttacks/About-Heart-Attacks%5FUCM%5F002038%5FArticle.jsp. Updated September 2, 2014. Accessed September 29, 2014.

    ST-elevation myocardial infarction (STEMI). EBSCO DynaMed Plus website. Available at: http://www.dynamed.com/topics/dmp~AN~T115392/ST-elevation-myocardial-infarction-STEMI. Updated July 25, 2016. Accessed September 28, 2016.

    What is a heart attack? National Heart Lung and Blood Institute website. Available at: http://www.nhlbi.nih.gov/health/health-topics/topics/heartattack/. Updated December 13, 2013. Accessed September 29, 2014.

    7/6/2009 DynaMed Plus Systematic Literature Surveillance http://www.dynamed.com/topics/dmp~AN~T115392/ST-elevation-myocardial-infarction-STEMI: Antithrombotic Trialists' (ATT) Collaboration, Baigent C, Blackwell L, et al. Aspirin in the primary and secondary prevention of vascular disease: collaborative meta-analysis of individual participant data from randomised trials. Lancet. 2009;373:1849-1860.

    2/3/2014 DynaMed Plus Systematic Literature Surveillance http://www.dynamed.com/topics/dmp~AN~T115392/ST-elevation-myocardial-infarction-STEMI: Finkle W, Greenland S, et al. Increased risk of non-fatal myocardial infarction following testosterone therapy prescription in men. PLoS One. 2014;9(1).

    7/17/2017 DynaMed Plus Systematic Literature Surveillance http://www.dynamed.com/topics/dmp~AN~T116779/Acute-coronary-syndromes: Bally M, Dendukuri N, Rich B, et al. Risk of acute myocardial infarction with NSAIDs in real world use: bayesian meta-analysis of individual patient data. BMJ. 2017;357:j1909.

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