Syncope is a symptom defined as a transient loss of consciousness, of rapid onset, of short duration and with complete and spontaneous recovery. Peaks of presentation are in adolescence and after the 8th decade of life. The incidence of syncope represents 1% to 3% of hospital admissions and is associated with cardiovascular comorbidity and cardiovascular pharmacotherapy, being an important cause of morbidity and mortality in the elderly. The accumulative incidence of syncope in women is almost double than in men. Its onset is explained by a decrease in cerebral blood flow due to the decrease in cardiac output, whether due to a drop in systolic blood pressure below 60 mmHg or a decrease in peripheral resistance. The syncope is divides into 3 groups: 1) Reflex syncope, in which there is a sudden change in the autonomic nervous system activity that leads to a drop in blood pressure; 2) Syncope secondary to orthostatic hypotension, where sympathetic efferent activity does not provide sufficient vasoconstriction; and 3) Syncope of cardiopulmonary cause, characterized by an abrupt and sudden decrease in cardiac output due to arrhythmias or structural heart diseases. Depending on the cause of syncope it may or may not present prodrome, which is more commonly composed of diaphoresis, heat and flushing. True loss of consciousness usually lasts less than a minute, although some patients may take several minutes to fully regain consciousness. Therefore, the diagnosis is based on a good medical history with a complete physical examination. Treatment depends on the cause and mechanism of syncopal episodes. In addition, the goals should be to alleviate symptoms and improve prognosis, which means avoiding or reducing recurrences.
