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Heart Attack (Myocardial Infarction)

A heart attack occurs if the flow of oxygen-rich blood to a section of heart muscle suddenly becomes blocked. If blood flow isn't restored quickly, the section of heart muscle begins to die.

PubMed Health Glossary
(Source: NIH - National Heart, Lung, and Blood Institute)

About Heart Attack

A heart attack happens when the flow of oxygen-rich blood to a section of heart muscle suddenly becomes blocked and the heart can't get oxygen. If blood flow isn't restored quickly, the section of heart muscle begins to die.

Heart attacks are a leading killer of both men and women in the United States. The good news is that excellent treatments are available for heart attacks. These treatments can save lives and prevent disabilities.

Heart attack treatment works best when it's given right after symptoms occur. If you think you or someone else is having a heart attack (even if you're not fully sure), call 9-1-1 right away.

Overview

Heart attacks most often occur as a result of coronary heart disease (CHD), also called coronary artery disease. CHD is a condition in which a waxy substance called plaque (plak) builds up inside the coronary arteries. These arteries supply oxygen-rich blood to your... Read more about Heart Attack

What works? Research summarized

Evidence reviews

Inotropic and vasodilator strategies in patients with a heart attack (acute myocardial infarction) and cardiogenic shock or low cardiac output

Cardiogenic shock occurring in 5% to 10% of patients with acute myocardial infarction still remains a life‐threatening complication. As regards treatment options with inotropic and vasoactive drugs for infarct related cardiogenic shock, there is only very little evidence generated by randomised controlled trials.

MI - Secondary Prevention: Secondary Prevention in Primary and Secondary Care for Patients Following a Myocardial Infarction: Partial Update of NICE CG48 [Internet]

Myocardial infarction (MI) remains one of the most dramatic presentations of coronary artery disease (CAD). Complete occlusion of the artery often produces myocardial necrosis and the classical picture of a heart attack with severe chest pain, electrocardiographic (ECG) changes of ST-segment elevation, and an elevated concentration of myocardial specific proteins in the circulation. Such people are described as having a ST-segment elevation myocardial infarction (STEMI). Intermittent or partial occlusion produces similar, but often less severe clinical features, although no or transient and undetected ST elevation. Such cases are described as a non-ST segment elevation myocardial infarction (NSTEMI). People who have suffered from either of these conditions are amenable to treatment to reduce the risk of further MI or other manifestations of vascular disease, secondary prevention.

Unstable Angina and NSTEMI: The Early Management of Unstable Angina and Non-ST-Segment-Elevation Myocardial Infarction

The development of cholesterol-rich plaque within the walls of coronary arteries (atherosclerosis) is the pathological process which underlies ‘coronary artery disease’. However, the clinical manifestations of this generic condition are varied. When the atherosclerotic process advances insidiously the lumen of a coronary artery becomes progressively narrowed blood supply to the myocardium is compromised (ischaemia) and the affected individual will often develop predictable exertional chest discomfort, or ‘stable’ angina. However, at any stage in the development of atherosclerosis, and often when the coronary artery lumen is narrowed only slightly or not at all, an unstable plaque may develop a tear of its inner lining cell layer (intima), exposing the underlying cholesterol rich atheroma within the vessel wall to the blood flowing in the lumen. This exposure stimulates platelet aggregation and subsequent clot (thrombus) formation.

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Summaries for consumers

Inotropic and vasodilator strategies in patients with a heart attack (acute myocardial infarction) and cardiogenic shock or low cardiac output

Cardiogenic shock occurring in 5% to 10% of patients with acute myocardial infarction still remains a life‐threatening complication. As regards treatment options with inotropic and vasoactive drugs for infarct related cardiogenic shock, there is only very little evidence generated by randomised controlled trials.

Danshen (Chinese medicinal herb) preparations for acute myocardial infarction

Danshen ‐ a Chinese herbal treatment ‐ is widely used in China in addition to usual western forms of therapy in the treatment of acute myocardial infarction (AMI). However there is no strong evidence to support its use, and few rigorous studies have been conducted. Well designed and conducted randomised controlled trials are needed to provide adequate evidence of its role in the treatment of AMI.

Bed rest for acute uncomplicated myocardial infarction

Bed rest is an inherent part of treatment for acute myocardial infarction (AMI). In clinical practice this intervention is prescribed in different ways and for different lengths of time. Current guidelines recommend at least 12 hours bed rest following AMI. However the basis for these recommendations is unclear. This review found 15 trials which were generally outdated and of moderate to poor methodological quality. Bed rest ranging from 2 to 12 days appears to be as safe as longer periods of bed rest. No evidence was found to support the current bed rest recommendations of not more than 12 to 24 hours. The optimal duration of bed rest after AMI remains undetermined from the available evidence.

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Terms to know

Coronary Artery
A principal artery that originates in the aorta. It supplies blood to the muscular tissue of the heart.
Heart
The hollow, muscular organ that maintains the circulation of the blood.
Muscles
Muscles function to produce force and motion. They are primarily responsible for maintaining and changing posture, locomotion, as well as movement of internal organs, such as the contraction of the heart and the movement of food through the digestive system.
Oxygen
A colorless, odorless gas. It is needed for animal and plant life. Oxygen that is breathed in enters the blood from the lungs and travels to the tissues.
Plaque
In medicine, a small, abnormal patch of tissue on a body part or an organ. Plaques may also be a build-up of substances from a fluid, such as cholesterol in the blood vessels.

More about Heart Attack

Photo of an adult

Also called: Cardiac infarction, Coronary attack, Infarction of heart, Myocardial infarct, MI

See Also: Coronary Heart Disease, Atherosclerosis

Other terms to know: See all 5
Coronary Artery, Heart, Muscles

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