Related Experiment Video
Updated: Jul 20, 2026
07:12
Real-Time Monitoring of Neurocritical Patients with Diffuse Optical Spectroscopies
Published on: November 19, 2020
Wave reflection analysis of the human cerebral circulation during syncope
1Autonomic Laboratory, Department of Neurology, Alfried Krupp Krankenhaus, Alfried-Krupp Strasse 21, 45117 Essen, Germany. rolf.diehl@krupp-krankenhaus.de
Autonomic Neuroscience : Basic & Clinical
|September 19, 2006
Summary
Wave reflection analysis reveals new insights into cerebral blood flow changes during vasovagal syncope. This study explains typical alterations in cerebral blood flow velocity (CBFV) by identifying a wave reflection site in cerebrovascular vessels.
Area of Science:
- Neuroscience
- Cardiovascular Physiology
- Biomedical Engineering
Background:
- Cerebral circulation studies have historically overlooked wave reflection phenomena.
- Understanding dynamic changes in cerebral blood flow velocity (CBFV) during syncope is crucial.
Purpose of the Study:
- To test the hypothesis that wave reflection in cerebrovascular vessels explains CBFV changes during vasovagal syncope.
- To investigate the role of wave reflection analysis (WRA) in characterizing syncope-induced hemodynamic alterations.
Main Methods:
- Continuous recording of arterial blood pressure (ABP) and CBFV using Finapres and transcranial Doppler, respectively.
- Wave reflection analysis (WRA) employing multivariate regression to assess ABP's influence on CBFV at varying time lags.
- Comparison of WRA with univariate regression analysis.
Main Results:
- In supine subjects, univariate regression adequately explained CBFV (88-90% variance), with no significant improvement from WRA.
- During syncope, WRA significantly improved CBFV prediction (from 58% to 77% explained variance) in 90% of patients.
- A mean reflection time of 160 ms was identified, correlating with characteristic diastolic flow wave distortions.
Conclusions:
- Wave reflection analysis provides a valuable tool for understanding cerebral hemodynamics during syncope.
- The findings suggest that collapse of distal bridging veins during hypotension creates a backward pressure wave, altering flow dynamics.
- WRA can account for specific changes in diastolic flow shape observed during vasovagal syncope.
Related Concept Videos
01:26Transient Ischemic Attack l: Introduction
A transient ischemic attack (TIA) is a brief episode of neurological dysfunction caused by a temporary, focal reduction in cerebral blood flow. Although symptoms resemble those of an ischemic stroke, the interruption in perfusion is short-lived and does not cause permanent infarction. TIAs are clinically important because they often serve as early warning events for future stroke.Mechanisms of Transient Cerebral IschemiaTransient cerebral ischemia may arise through several mechanisms. One...
01:17Hemorrhagic Stroke l: Introduction
A hemorrhagic stroke is an acute neurological event that occurs when a weakened cerebral blood vessel ruptures, allowing blood to accumulate within or around the brain. The sudden release of blood forms a focal hematoma that increases intracranial pressure, displaces neural tissue, and can obstruct cerebrospinal fluid pathways. These effects may be compounded by intraventricular extension of the hemorrhage, cerebral edema, or compression of adjacent structures, all of which contribute to...
01:29Hemorrhagic Stroke ll: Pathophysiology
A hemorrhagic stroke develops when a cerebral blood vessel ruptures, allowing blood to escape into the surrounding brain tissue, as in intracerebral hemorrhage (ICH), or into the subarachnoid space, as in subarachnoid hemorrhage (SAH). Because the skull is a rigid compartment, the sudden presence of extravascular blood rapidly increases intracranial pressure and compresses adjacent neural structures, leading to immediate tissue injury and impaired cerebral perfusion.Mass Effect and Primary...