Transcranial Doppler Ultrasonography Monitoring during Head-up Tilt Test in Patients with Recurrent Syncope and Presyncope |
Soo-Jin Cho, Kwang-Ho Lee, and Chin-Sang Chung |
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Copyright © 1999 The Korean Society of Clinical Neurophysiology |
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium,
provided the original work is properly cited. |
ABSTRACT |
Background : Syncope was defined as transient loss of consciousness and postural tone. The mechanisms of changes in cerebral hemodynamics during syncope have not been fully evaluated. Transcranial Doppler Ultrasonography can continuously monitor the changes in cerebral hemodynamics during head-up tilt (HUT). TCD could reveal the different patterns of changes in cerebral hemodynamics during syncope. Syncope without hypotension or bradycardia could be detected by TCD. We investigated the changes in cerebral blood flow velocity during HUT using TCD in 33 patients with a history of recurrent syncope or presyncope of unknown origin. Methods & Results : The positive responses were defined as presyncope or syncope with hypotension, bradycardia, or both. During HUT without isoproterenol infusion, there were a 86?3% drop in DV and a 41?4% drop in SV in 5 patients with positive reponses, and mean changes in those were less than 10% in patients with negative reponses ( p=.00, p=.00). During HUT with isoproterenol infusion, TCD showed a 80?8% drop in diastolic velocity in 14 patients with positive reponses, and a 47?0% drop in that in patients with negative reponses (p=.00), however the change in systolic velocity did not differ. TCD showed three patterns during positive responses; loss of all flow, loss of end diastolic flow, and a decrease in diastolic velocity. Loss of consciousness occurred in the patients with loss of all flow or end-diastolic flow during positive reponses. Conclusions : TCD shows different patterns of changes in cerebral hemodynamics during HUT. TCD can be used to investigate the pathophysiology of neurocardiogenic syncope |
Key words:
Neurocardiogenic syncope, Syncope, Cerebral hemodynamics, Transcranial Doppler ultrasonography, Head-up tilt test |
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