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(Circulation. 2006;113:e715-e717.)
© 2006 American Heart Association, Inc.

Cardiology Patient Page

Syncope

Gunjan J. Shukla, MD; Peter J. Zimetbaum, MD

From Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Mass.

Correspondence to Gunjan J. Shukla, MD, Beth Israel Deaconess Medical Center, Harvard Medical School, 185 Pilgrim Rd, W/Palmer 402, Boston, MA 02215. E-mail gshukla@bidmc.harvard.edu

An extract of the first 250 words of the full text is provided, because this article has no abstract.

	Introduction

 
Syncope (SIN'ko-pe) is the sudden and temporary loss of consciousness that is also described as fainting or passing out. Usually, it occurs when a fall in blood pressure (BP) causes a disruption in the sustained oxygen supply to the brain. Typically, syncope lasts for several seconds, after which consciousness is regained. Some people with so-called syncope do not actually faint but come close to it. This is called presyncope and is akin to a dimming of the lights during a reduction in electric power.

Syncope is a common problem that affects 1 million Americans every year. It also accounts for 3% of all emergency department visits and 6% of all hospital visits. Approximately one third of us will have syncope at least once in our lifetime. Sometimes syncope indicates a life-threatening condition, and therefore it is important to rule out dangerous causes.

	What Causes Syncope?

 
The causes of syncope can be divided into 3 major categories: heart-related (cardiac), noncardiac, or unknown.

Cardiac Causes
Cardiac abnormalities can cause syncope through a temporary reduction in blood flow to the brain. This can occur if the heart’s electric system malfunctions (producing a heart rate that is abnormally slow or fast) or if there is an obstruction of blood flow out of the heart caused by a narrow heart valve or a thick heart muscle.

Excessively slow heart rate (bradyarrhythmia) (less than 40 beats per minute) can develop from dysfunction of the body’s natural pacemaker or damage to the electric network, which activates the heart muscle. These abnormalities develop . . . [Full Text of this Article]