Abstract

Syncope is a common syndrome occurring in about 2% of those 65-69 years old, increasing to 12% in those over age 85 [1]. Syncope deserves diagnostic analysis because, while unexplained syncope is associated with a slight increased mortality rate within 1 year, when syncope can be linked to a cardiovascular cause, the 1-year mortality rate is 20% to 30% [1]. Syncope is defined as the transient loss of consciousness with a lack of responsiveness and postural tone, followed by spontaneous recovery. Consciousness is lost when the function of both cerebral hemispheres or of the brain stem reticular activating system is compromised. Interruption of cerebral blood flow and/or the occurrence of severe hypoxemia (arterial oxygen pressure Pa02 > 15 mmHg) to the cerebral hemispheres or brain stem results in loss of consciousness within 10 s [2]. A fall in systolic blood pressure less than 90 mmHg or a mean blood pressure of 30 to 40 mmHg results in syncope. Within 20 s spontaneous and evoked electrical activity ceases and a series of metabolic disturbances occur, leading to convulsive movements, and death of the cerebral cortex in 3 to 6 min [2]. The critical

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