Regional cerebral perfusion in cardiovascular reflex syncope

Area of Science:

• Neurology
• Cardiology
• Medical Imaging

Background:

• Regional cerebral perfusion in presyncope and syncope is not well understood.
• The influence of autonomic nervous dysfunction on cerebral blood flow during these events requires further investigation.

Purpose of the Study:

• To investigate regional cerebral perfusion changes during vasodepressor syncope.
• To assess the impact of autonomic nervous dysfunction on cerebral perfusion during syncope provocation.

Main Methods:

• Utilized single-photon emission tomography (SPECT) with technetium-99m labelled V-oxo-1,2-N, N1-ethylenedylbis-l-cysteine diethylester for regional cerebral perfusion assessment.
• Employed head-up tilt table testing with and without isoprenaline infusion for syncope provocation.
• Assessed autonomic nervous function via spectral analysis of heart rate variability.

Main Results:

• All seven subjects experienced significant blood pressure decline during provocation (five presyncope, two syncope).
• Mean cerebral perfusion decreased significantly during provocation compared to baseline (307+/-90 vs 190+/-63 counts/voxel, P=0.013).
• Cerebral hypoperfusion was most pronounced in the frontal lobe; autonomic function remained unchanged before blood pressure decline.

Conclusions:

• Cerebral perfusion markedly decreases during presyncope or syncope associated with systemic blood pressure decline in cardiovascular vasodepressor syncope.
• Autonomic nervous function does not appear to change prior to the systemic blood pressure decline in these patients.