Thursday, May 23, 2013

Heart Attack and Acute Coronary Syndrome

Table of Contents

Introduction


The heart is the human body's hardest working organ. Throughout life it continuously pumps blood enriched with oxygen and vital nutrients through a network of arteries to all tissues of the body. To perform this strenuous task, the heart muscle itself needs a plentiful supply of oxygen-rich blood, provided through a network of coronary arteries. These arteries carry oxygen-rich blood to the heart's muscular walls (the myocardium).

A heart attack (myocardial infarction) occurs when blood flow to the heart muscle is blocked, and tissue death occurs from loss of oxygen, severely damaging a portion of the heart.

Anterior heart arteries

Coronary Artery Disease. Coronary artery disease causes nearly all heart attacks. Coronary artery disease is the end result of a complex process called atherosclerosis (commonly called "hardening of the arteries"). This causes blockage of arteries (ischemia) and prevents oxygen-rich blood from reaching the heart. [For more information, see In-Depth Report #3: Coronary artery disease.]

Click the icon to see an image of atherosclerosis.

Heart Attack

Heart attack (myocardial infarction) is among the most serious outcome of atherosclerosis. It can occur as a result of one of two effects of atherosclerosis:

  • If the plaque develops fissures or tears. Blood platelets adhere to the site to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot completely blocks the passage of oxygen-rich blood to the heart.
  • If the artery becomes completely blocked after gradual buildup of plaque due to atherosclerosis. Heart attack may occur if not enough oxygen containing blood can flow through this blockage.
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Review Date: 05/05/2011
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)