Vasovagal syncope is a common form of fainting that occurs when the nervous system overreacts to certain triggers, such as the sight of blood, pain, emotional distress, or prolonged standing. This overreaction causes a sudden drop in heart rate and blood pressure, leading to reduced blood flow to the brain and a brief loss of consciousness. It is usually harmless but can sometimes result in injury from falling.
Causes and Triggers
Vasovagal syncope happens due to a reflex arc involving the autonomic nervous system. Triggers include intense emotional stress, pain, dehydration, prolonged standing, and even seeing blood or needles. The trigger causes increased vagal (parasympathetic) activity and decreased sympathetic nervous activity, which slows the heart rate and dilates blood vessels, lowering blood pressure and cerebral perfusion.
Symptoms
Before fainting, symptoms often include lightheadedness, dizziness, tunnel vision, nausea, cold clammy sweat, and blurred vision. During an episode, a slow and weak pulse, jerky movements, and dilated pupils may be observed. Recovery usually happens within a minute once blood flow to the brain is restored, often by lying down.
Management and When to Seek Help
Vasovagal syncope often does not require treatment but recognizing early symptoms can help prevent injury. Strategies include lying down and elevating the legs or sitting with the head between the knees when feeling faint. Medical evaluation is recommended, especially for first-time episodes, to exclude other serious causes like heart or neurological conditions. Vasovagal syncope is also known as neurocardiogenic syncope and represents a benign reflex response, although it can be disabling if recurrent or associated with injury risk.
