Vasovagal Syncope is a common cause of fainting (syncope) characterised by a sudden drop in heart rate and blood pressure, leading to a temporary loss of consciousness.
It is often triggered by a strong emotional or physical response that stimulates the vagus nerve, resulting in a reflex response that causes the heart to slow down and blood vessels to dilate, leading to a sudden drop in blood pressure.
Quite common but important to distinguish from more sinister reasons for the collapse History from a observer is invaluable for diagnosis
It cannot be vasovagal if it occurs when lying down
Onset is over a few seconds - not instantaneous. Often with pre-syncopal symptoms - nausea, vomiting, sweating
Urinary Incontinence is uncommon and there is no tongue biting
LoC usually lasts for around 2 mins
Causes/Factors
The primary causes and triggers for Vasovagal Syncope include:
- Emotional Stress: Anxiety, fear, or emotional distress.
- Pain: Severe pain or the sight of blood.
- Prolonged Standing: Especially in warm or crowded environments.
- Dehydration: Inadequate fluid intake.
- Heat Exposure: Especially in hot environments.
- Straining: Due to activities like coughing, sneezing, or bowel movements.
Symptoms & Signs
Symptoms of Vasovagal Syncope can include:
- Decreased pulse
- Dilated pupils - blurred vision
- Sweating
- Lightheaded
- Brief limb jerks may occur due to cerebral hypoperfusion - but there is no tonic/clonic sequence
Diagnostic tests
- Tilt Table Test: To induce fainting under controlled conditions.
- Electrocardiogram (ECG or EKG): To record the heart’s electrical activity.
- Blood Pressure Monitoring: To assess changes in blood pressure.
- Holter Monitor: Continuous monitoring of heart activity over a period.
Management
- Avoiding Triggers: Identifying and avoiding specific triggers.
- Hydration: Ensuring an adequate intake of fluids.
- Physical Counter-pressure Manoeuvres: Such as tensing leg muscles or crossing legs to prevent fainting.
- Medications: In some cases, medications that increase blood volume or constrict blood vessels may be prescribed.
- Tilt Training: A supervised exercise program to improve tolerance to standing.