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Syncope: Difference between revisions
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Reflex syncope refers to a heterogeneous group of conditions in which there is a relatively sudden change in autonomic nervous system activity (decreased sympathic tonus causing less vasoconstriction and increased parasympathic (vagal) tonus causing bradycardia), triggered by a central (e.g. emotions, pain, blood phobia) or peripheral (e.g. prolonged orthostasis or increased carotid sinus afferent activity). It leads to a fall in blood pressure and cerebral perfusion. The range of bradycardia varies widely in reflex syncope, from a small reduction in peak heart rate to several seconds of asystole. As reflex syncope requires a reversal of the normal autonomic outflow, it usually occurs in people with a functional autonomic nervous system and should therfore be distinguished from syncope due to neurogenic orthostatic hypotension in patients with chronic autonomic failure. | Reflex syncope refers to a heterogeneous group of conditions in which there is a relatively sudden change in autonomic nervous system activity (decreased sympathic tonus causing less vasoconstriction and increased parasympathic (vagal) tonus causing bradycardia), triggered by a central (e.g. emotions, pain, blood phobia) or peripheral (e.g. prolonged orthostasis or increased carotid sinus afferent activity). It leads to a fall in blood pressure and cerebral perfusion. The range of bradycardia varies widely in reflex syncope, from a small reduction in peak heart rate to several seconds of asystole. As reflex syncope requires a reversal of the normal autonomic outflow, it usually occurs in people with a functional autonomic nervous system and should therfore be distinguished from syncope due to neurogenic orthostatic hypotension in patients with chronic autonomic failure. | ||
Adequate history taking reveals the clinical features associated with a syncopal event that are important to differentiate the different causes of syncope. Vasovagal syncope, a specific form of reflex syncope, is diagnosed if syncope is precipitated by emotional distress or orthostatic stress and is associated with typical prodrome (such as nausea, warmth, pallor, lightheadedness, and/or diaphoresis). | Adequate history taking reveals the clinical features associated with a syncopal event that are important to differentiate the different causes of syncope. Vasovagal syncope, a specific form of reflex syncope, is diagnosed if syncope is precipitated by emotional distress or orthostatic stress and is associated with typical prodrome (such as nausea, warmth, pallor, lightheadedness, and/or diaphoresis). | ||
Head-up-tilt testing is used to examine the susceptibility to reflex syncope in patients who present with syncope of unknown cause. During head-up-tilt-testing a patient is passively changed from supine to upright position using a tilt-table. | |||
===Treatment=== | ===Treatment=== | ||