During a vasovagal episode, which statement best describes autonomic changes?

During a vasovagal episode, which statement best describes autonomic changes?

• A. Increased parasympathetic tone causing bradycardia and vasodilation
• B. Increased sympathetic tone causing vasoconstriction
• C. No autonomic change
• D. Only muscle activity changes

Answer: (A)

A vasovagal episode is driven by a reflex that increases parasympathetic (vagal) activity while decreasing sympathetic drive. This autonomic shift slows the heart (bradycardia) and relaxes the blood vessels (vasodilation). The drop in heart rate and vascular resistance reduces blood pressure and cerebral blood flow, leading to faintness or syncope. So the concept shown is that heightened parasympathetic activity causes bradycardia and vasodilation. If sympathetic tone were increasing, you’d expect vasoconstriction and a faster heart rate, not bradycardia and dilation. And this response is driven by autonomic changes, not just muscle activity.

A vasovagal episode is driven by a reflex that increases parasympathetic (vagal) activity while decreasing sympathetic drive. This autonomic shift slows the heart (bradycardia) and relaxes the blood vessels (vasodilation). The drop in heart rate and vascular resistance reduces blood pressure and cerebral blood flow, leading to faintness or syncope. So the concept shown is that heightened parasympathetic activity causes bradycardia and vasodilation. If sympathetic tone were increasing, you’d expect vasoconstriction and a faster heart rate, not bradycardia and dilation. And this response is driven by autonomic changes, not just muscle activity.