Syncope is a loss of consciousness (fainting) that occurs when
blood pressure drops very low and not enough blood reaches the brain. A person
may have shortness of breath, palpitations, or chest discomfort before
fainting.
The reduction in blood flow usually happens quickly, which causes
symptoms to appear suddenly.
Syncope can be caused by several conditions, but it most often
occurs when changes in heart rate or heart rhythm reduce the amount of blood
flow to the body. Fainting caused by a problem in the heart is called cardiac
syncope. Other types of syncope that are not linked with heart problems
include neurally mediated syncope, also called vasovagal, neurocardiogenic, and
vasodepressor syncope.
Syncope requires medical attention.