by EBSCO Medical Review Board

A heart attack is caused by a sudden loss of blood flow to the heart muscle. The loss of blood will make it hard or impossible for the heart to pump blood out to the body. Heart tissue can also die if blood flow is stopped long enough. This leads to permanent damage. Heart attacks can range from minor to severe and fatal. The outcome is based on how much heart tissue was affected and what care was given.

Immediate medical care can make a drastic difference in the outcome of most heart attacks.

Heart Attack
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Causes of Heart Attack

All cells in the body need oxygen. Working muscles like the heart need a regular supply of oxygen. Blood vessels called coronary arteries carry oxygen to heart muscle. A blockage in these arteries causes immediate problems. Heart cells will die within a few minutes when they do not get the oxygen they need. A blockage in a large artery will affect a larger area of the heart. This will lead to a more severe heart attack. A blockage in a smaller blood vessel will affect a smaller area. It will cause a minor heart attack. The amount of damage will also depend on the degree of blockage. The artery may be completely blocked, others may only be blocked when the blood vessel squeezes down.

Blood flow through the coronary arteries can be slowed or blocked by:

Atherosclerosis and Coronary Artery Disease

Atherosclerosis is the buildup of plaque in the arteries. It builds up over many years. Items in your blood, such as fat and cholesterol, stick to blood vessel walls and slowly build up a hardened plaque. This causes tears in the wall of the artery. Blood clots help the wall heal but also adds to the bulk of the plaque. The plaque narrows the artery as it grows. This makes it easier for new blood clots or plaque build up to completely block the artery and stop blood flow.

Coronary artery disease (CAD) is reduced blood flow to the heart because of plaque buildup. It is the leading killer of men and women in the US. A heart attack can be the first sign of CAD.

Blood Clots in the Heart
Copyright © 2002 Nucleus Communications, Inc. All rights reserved.
Coronary Artery Spasm

The muscular walls of blood vessels tighten or loosen to help blood flow. It is controlled by the nervous system to help manage blood flow and blood pressure. Illnesses, injuries, or medicine and supplements can cause these muscles to spasm and tighten. It will slow the flow of blood to the heart. In a blood vessel with plaque buildup this could easily lead to a complete blockage of blood flow.

Blood Clot

Blood clots collect around an injury site or where blood has pooled. Blood clots that form in blood vessels can break off and travel in the blood stream. It can travel through the body until it becomes stuck in smaller blood vessels. There it will block blood flow until the body can clear the clot. A heart attack happens when the clot sticks in one of the coronary arteries.

What are the risk factors for heart attack?What are the symptoms of heart attack?How is heart attack diagnosed?What are the treatments for heart attack?Are there screening tests for heart attack?How can I reduce my risk of heart attack?What questions should I ask my doctor?Where can I get more information about heart attack?


About heart attacks. American Heart Association website. Available at: Accessed March 28, 2019.

Acute coronary syndromes. EBSCO DynaMed Plus website. Available at: . Updated March 15, 2019. Accessed March 28, 2019.

Acute myocardial infarction (MI). Merck Manual Professional Version website. Available at: Updated December 2018. Accessed March 28, 2019.

ST-elevation myocardial infarction (STEMI). EBSCO DynaMed Plus website. Available at: . Updated July 10, 2018. Accessed March 28, 2019.

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