Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower (a condition known as stenosis).

• As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles.
• Such oxygen deprivation in vital cells is called ischemia. When it affects the coronary arteries, it causes injury to the tissues of the heart.
• These narrow and inelastic arteries not only slow down blood flow but also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.

Click the icon to see an image of coronary artery blockage

The End Result: Heart Attack. A heart attack can occur as a result of one or two effects of atherosclerosis:

• The plaque itself develops fissures or tears. Blood platelets stick 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.
• Less commonly, the artery becomes completely blocked by plaque itself, and ischemia becomes so extensive that oxygen-bearing tissues around the heart die.

Click the icon to see an image of the developmental process of atherosclerosis.

Click the icon to see an image of the anterior heart arteries.

Click the icon to see an animation about coronary artery disease.

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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)