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Transcranial Doppler during neurocardiogenic syncope
R R Diehl1, D Linden, A Chalkiadaki
1Department of Neurology and Clinical Neurophysiology, Alfried Krupp Hospital, Essen, Germany.
Summary
Neurocardiogenic syncope (NCS) involves significant cerebral vasoconstriction, not just reduced blood pressure and heart rate. This cerebral artery narrowing is a key factor in NCS development.
Area of Science:
- Neurology
- Cardiology
- Physiology
Background:
- Neurocardiogenic syncope (NCS) is a common cause of unexplained fainting.
- The exact mechanisms of cerebral blood flow changes during NCS require further elucidation.
Purpose of the Study:
- To investigate alterations in cerebral circulation during neurocardiogenic syncope (NCS).
- To understand the role of cerebral vasoconstriction in NCS pathogenesis.
Main Methods:
- Twenty patients with a history of syncope underwent a 45-minute tilt test.
- Non-invasive monitoring of heart rate and arterial blood pressure (Finapres).
- Transcranial Doppler (TCD) used to measure middle cerebral artery blood flow velocity.
Main Results:
- 50% of patients developed NCS, characterized by significant drops in blood pressure and heart rate.
- Diastolic cerebral blood flow velocity decreased sharply, while systolic velocity remained stable.
- Pulsatility index (PI) increased significantly, indicating heightened cerebrovascular resistance.
- Systolic velocity stability suggests lumen narrowing in cerebral arteries during NCS.
Conclusions:
- Cerebral vasoconstriction, affecting both proximal and peripheral cerebral arteries, is a crucial mechanism in NCS.
- Cerebral vasoconstriction, alongside vasodepression and cardiac inhibition, contributes to NCS development.
- Findings highlight the importance of cerebral hemodynamics in the pathophysiology of neurocardiogenic syncope.