Fainting, also known as syncope (SIN-cuh-pee), is a brief, sudden loss of consciousness, usually followed by a rapid return to consciousness. Syncope is a symptom of an underlying cause or condition, not a disease itself. It may be due to harmless causes or it may be due to more serious underlying cardiovascular or neurologic conditions.

In patients with heart disease, the possibility that a fainting spell may have been caused by an abnormal heart rhythm (arrhythmia) needs to be carefully considered. Therefore, patients with heart disease (and, indeed, anyone) should inform their physician of any episodes of fainting or near-fainting as soon as possible after the event.

Tests that may be run include a tilt table test, which is used to assess neurocardiogenic syncope – fainting due to a reflex that leads to a sudden drop in heart rate and blood pressure. Other tests that may be run include an echocardiogram, a stress test, a Holter monitor (or event monitor), a cardiac catheterization or an electrophysiologic study. In addition, a CAT scan or an MRI may be used to evaluate possible neurologic causes.

Treatment will depend on the underlying cause.