What is vasovagal syncope?
May 25, 2022
Source: Cainiu Health
Dr. Li Man
Introduction
Triggers include standing up, physical exertion, mental stress, hunger, and severe pain. These stimuli cause a redistribution of blood flow—such as due to gravity or visceral movement—diverting blood supply away from the heart and thereby reducing venous return. This leads to bradycardia and hypotension, resulting in symptoms such as syncope and transient visual obscurations (e.g., “graying out” or “blackout”). Reduced intravascular volume further contributes to bradycardia, vasodilation, hypotension, and inadequate cerebral perfusion, culminating in vasovagal syncope.
Vasovagal syncope commonly occurs in healthy individuals and typically manifests immediately upon standing or changing from a supine to upright position. So, what exactly is vasovagal syncope?
What Is Vasovagal Syncope?
The etiology and pathophysiology of vasovagal syncope are not fully understood. It is thought to result from increased vagal tone, leading to bradycardia and hypotension, which in turn cause palpitations, chest tightness, dizziness, nausea, vomiting, and even loss of consciousness. This is the most common type of syncope. Predisposing factors include irregular eating habits, physical debility, excessive psychological stress, and overexertion. Following brief loss of consciousness, spontaneous recovery usually occurs. Diagnosis relies primarily on characteristic clinical symptoms and signs, supplemented by electrocardiography (ECG), electroencephalography (EEG), and tilt-table testing.
Vasovagal syncope occurs most frequently among school-aged girls. Menstruation may reduce intravascular volume and blood volume, resulting in bradycardia, peripheral vasodilation, hypotension, and insufficient cerebral perfusion—thereby triggering vasovagal syncope. The underlying cause in adolescents is heightened carotid sinus sensitivity and immature autonomic nervous system regulation. In elderly individuals, advancing age leads to increased blood viscosity and reduced circulating blood volume, making them more susceptible to syncope upon rapid postural changes—such as standing up quickly after lying down.
Patients exhibiting prodromal symptoms suggestive of vasovagal syncope should seek prompt medical evaluation and hospital admission for further diagnostic workup. We hope this article has been helpful to you!
