Neurally mediated reflex syncope (NMRS) refers to a group of related conditions or scenarios in which symptomatic hypotension occurs as a result of neural reflex vasodilation and/or bradycardia.
Vasovagal syncope (VS) refers to a particular type of NMRS also known as the common faint.
VS has many manifestations and is generally considered to encompass faints triggered by emotional upset, fear, and pain, as well as other less well-defined circumstances.
Patient education is the foundation of treatment for most NMRS syndromes, including VS.
Patients must be informed that, although reflex faints are almost never life-threatening, they tend to recur (often in clusters), and injury can result if preventive measures are not taken seriously.
Strategies for reducing syncope recurrences in the long term comprise 1) physical techniques to improve orthostatic tolerance, 2) pharmacological interventions to prevent depletion of intravascular volume and/or enhance arterial and venous tone, 3) cardiac pacing to avert bradycardia.
Syncope is a syndrome characterised by a relatively sudden, temporary, and self-terminating loss of consciousness, associated with the inability to maintain postural tone, with rapid and spontaneous recovery. The causes vary widely from patient to patient, but they have a common underlying pathophysiology. The transient loss of consciousness with syncope is the result of a temporary inadequacy of cerebral nutrient flow, most often triggered by a fall in systemic arterial pressure below the minimum needed to sustain cerebral blood flow. Neurally mediated reflex syncope (NMRS) refers to a group of related conditions or scenarios in which symptomatic hypotension occurs as a result of neural reflex vasodilation and/or bradycardia. Vasovagal syncope (VS) refers to a particular type of NMRS also known as the common faint.
History and exam
Other diagnostic factors
- history of recurrent faints
- absence of structural heart disease
- provocative factor
- diminished vision or hearing
- physical injury
- fatigue after episode
- absence of family history of sudden death
- prior syncope
- prior history of arrhythmias, myocardial infarction, heart failure, or cardiomyopathy
- severe aortic stenosis
- prolonged standing
- emotional stress (especially in a warm, crowded environment)
- preceding episode of nausea and/or vomiting
- preceding episode of severe pain
1st investigations to order
- 12-lead ECG
- serum haemoglobin
- plasma blood glucose
- serum beta-hCG (human chorionic gonadotrophin)
- cardiac enzymes
- D-dimer level
- serum cortisol
- urea or serum creatinine
Investigations to consider
- tilt-table test
- carotid sinus massage (CSM)
- insertable loop recorder
- electrophysiological study
- Valsalva manoeuvre
- active standing test
- cold pressor test
- cough test
- adenosine triphosphate (ATP) test
carotid sinus syndrome
- Orthostatic syncope (postural or orthostatic intolerance syncope syndromes)
- Bradycardia: AV conduction disorders
- Recommendations for tilt table testing and other provocative cardiovascular autonomic tests in conditions that may cause transient loss of consciousness
- Clinical practice update on the assessment and management of syncope
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