What is the result of a parasympathetic response during neuro-cardiogenic syncope?

What is the result of a parasympathetic response during neuro-cardiogenic syncope?

• A. Increased cardiac output
• B. Decreased cardiac output
• C. Increased blood flow to the extremities
• D. Increased blood pressure

Answer: (B)

During a parasympathetic response, particularly in the context of neuro-cardiogenic syncope, there is a notable decrease in heart rate and a reduction in cardiac output. This response is part of the body’s natural mechanism to counter stressors; however, in cases such as neuro-cardiogenic syncope (which involves an abnormal reflex mediated by the autonomic nervous system), the parasympathetic activation leads to vasodilation and a drop in heart rate, resulting in insufficient blood flow to the brain. Consequently, this can cause syncope or fainting due to compromised cerebral perfusion.

The mechanisms involve increased vagal tone which prompts the slowing of the heart rate (bradycardia) and relaxation of peripheral blood vessels. This combination ultimately leads to the decreased cardiac output, making it more challenging for the heart to maintain adequate blood flow, particularly to the brain and other vital organs. Understanding this response is crucial for interpreting the neurological implications of syncope in patients experiencing these autonomic dysregulations.