Syncope is a symptom defined as a transient, self-limited loss of consciousness, usually leading to a fall. Thirty percent of the adult population will experience at least one episode of syncope. It accounts for approximately 3% of emergency department visits. A specific cause of syncope is identified in about 50% of cases during the initial evaluation.
The prognosis is relatively favorable except when accompanying cardiac disease is present. In many patients with recurrent syncope or near syncope, arrhythmias are not the cause. This is particularly true when the patient has no evidence of associated heart disease by history, examination, standard ECG, or noninvasive testing. The history is the most important of the evaluation to identify the cause of syncope.
Common causes of syncope include:
• low blood pressure or dilated blood vessels
• irregular heart beat
• abrupt changes in posture, such as standing up too quickly, which can cause blood to pool in the feet or legs
• standing for long periods of time
• extreme pain or fear
• extreme stress