Neurally mediated syncopal syndromes: pathophysiological concepts and clinical evaluation

Area of Science:

• Cardiology
• Neurology
• Physiology

Background:

• Neurally mediated syncopal syndromes are disturbances of reflex cardiovascular control, causing transient bradycardia and/or vasodilation.
• Vasovagal syncope is a frequent cause of syncope, making these syndromes clinically significant.
• Pathophysiology involves afferent and efferent limbs, central nervous system processing, and feedback loops, leading to hypotension.

Purpose of the Study:

• To review the diagnostic utility of head-up tilt table testing for neurally mediated syncope.
• To discuss the current understanding of pathophysiology and diagnostic approaches.
• To evaluate the controversial treatment strategies for neurally mediated syncope.

Main Methods:

• Review of existing literature on neurally mediated syncope and diagnostic techniques.
• Analysis of head-up tilt table testing as a diagnostic modality.
• Discussion of pathophysiological mechanisms and treatment options.

Main Results:

• Head-up tilt table testing is the preferred diagnostic method for neurally mediated syncope, especially vasovagal syncope.
• Tilt testing shows good discrimination between symptomatic and asymptomatic individuals, with 10-15% false-positive rates.
• Sensitivity estimates for tilt testing range from 32-85%, with higher values more commonly reported.

Conclusions:

• Neurally mediated syncope is a common cause of syncope with complex pathophysiology.
• Head-up tilt table testing is a valuable diagnostic tool, but its sensitivity requires further validation.
• Treatment strategies remain controversial, with a need for large-scale clinical studies to evaluate pharmacological and pacing therapies.