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Gwinnett Medical Center

What Is Syncope?

If your blood pressure drops too low, your brain may not get enough oxygen-rich blood. Your body responds by losing consciousness briefly. You also slump or fall down. This problem is called syncope, fainting, or a blackout.

Man faints
Standing for a long time can cause syncope.

Understanding Heart Rate and Blood Pressure Changes

Your brain and body need a steady supply of oxygen-rich blood. Your heart rate and blood pressure adjust to maintain this steady supply throughout all your activities. The heart creates electrical signals that travel through it on pathways. These signals set the heart rate, and tell the heart when to pump blood. In response to your body’s needs, your brain may also trigger changes in your heart rate and blood pressure. This keeps your blood flow strong.

Warning Signs

Syncope happens suddenly. First you may have warning signs, including dimmed vision, lightheadedness, or a rapid heartbeat. Or you may have no warning signs at all. After syncope, you recover quickly, but you may feel tired.

Is It Serious?

Syncope is a common problem with many possible causes. Often these causes are not serious. For instance, syncope can be caused by standing for too long or sitting up too fast. In some cases, you may never faint again. But if heart trouble causes syncope, this can be serious. To provide the best treatment, your doctor will want to learn why you fainted. If heart trouble is causing your syncope, treatment may even save your life.

View of brain, arteries and heart
The heart pumps blood nonstop to the brain and the rest of the body.

© 2000-2014 The StayWell Company, LLC. 780 Township Line Road, Yardley, PA 19067. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.