Syncope is a medical term for fainting or blackouts. Technically speaking, it is defined as a transient loss of consciousness due to transient lack of blood to the brain.

The most common type by far is called vasovagal syncope (also known as 'reflex syncope' or 'the common faint'). People with this type of syncope typically experience warning symptoms before passing out such as sweating, weakness/lightheadedness, tunnel vision or nausea/vomiting. Fear/anxiety, dehydration, standing up rapidly and/or urinating/defecating may trigger this form of syncope. Vasovagal syncope is by far the most common cause of fainting and is not usually dangerous. 40% of all Canadians will experience a faint at least once in their lives.

When syncope happens without any warning ("blackout"), it may be related to a serious heart problem (often an abnormal heart rhythm). To distinguish between these types of syncope, your doctor may recommend certain tests such as an ECG, holter monitor, event recorder or implantable loop recorder. An implantable loop recorder is a small device inserted via a small skin incision near the heart which records abnormal heart rhythms for up to 3 years. Other ancillary tests to investigate syncope may also include a transthoracic echocardiogram, stress test or coronary angiogram. 

Disclaimer: The brief patient information supplied here and the outside links provided are not intended to replace the advice of your physician and are only meant to help guide patients to formulate questions during their physician appointments. Each patient's situation is unique and a large number of factors are considered when arriving at a management plan for your specific condition.