title: Transcranial Doppler monitoring during head upright tilt table testing in patients with suspected neurocardiogenic syncope.
abstract: The aim of the present study was to evaluate the mechanism of cerebrovascular autoregulation in patients with neurocardiogenic syncope using bilateral transcranial Doppler (TCD) monitoring during head upright tilt table testing (HUT). Two hundred and six patients were prospectively studied. One hundred and fifty-nine subjects (77%) had a prior history of syncope and 47 (23%) had presyncope. Ninety-nine patients (48%) had syncope or presyncope during HUT with a 76% fall in diastolic middle cerebral artery blood flow velocity (D-MCA-BFV). Systolic MCA-BFV (S-MCA-BFV) fell by 33%. Deepening of the dicrotic notch in the Doppler waveform always preceded the fall in D-MCA-BFV. Patients without syncope or presyncope (n=96) had smaller changes in cerebral blood flow velocities during HUT and only twenty-two subjects had transient deepening of the dicrotic notch. Eleven subjects had presyncope during HUT due to an exaggerated response to nitrates with progressive arterial hypotension without bradycardia and changes during TCD monitoring that were intermediate between positive and negative HUT. In conclusion, patients with neurocardiogenic syncope have changes in cerebral blood flow during the event. TCD monitoring during HUT helps to assess these alterations.
authors.affiliation: Cardiovascular Institute of Buenos Aires (ICBA), Blanco Encalada 1543, (1428) Buenos Aires, Argentina. albinag@netverk.com.ar
authors.forename: Gastón
authors.initials: G
authors.lastname: Albina
authors.forename: Lucía
authors.initials: L
authors.lastname: Fernandez Cisneros
authors.forename: Rubén
authors.initials: R
authors.lastname: Laiño
authors.forename: Ulises L
authors.initials: UL
authors.lastname: Nobo
authors.forename: Daniel
authors.initials: D
authors.lastname: Ortega
authors.forename: Elena
authors.initials: E
authors.lastname: Schwarz
authors.forename: Luis
authors.initials: L
authors.lastname: Barja
authors.forename: Roberto
authors.initials: R
authors.lastname: Lagos
authors.forename: Alberto
authors.initials: A
authors.lastname: Giniger
authors.forename: Sebastián F
authors.initials: SF
authors.lastname: Ameriso
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001783:Blood Flow Velocity; D002560:Cerebrovascular Circulation / Q000502:physiology*; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019462:Syncope, Vasovagal / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000503:physiopathology*; D018667:Tilt-Table Test; D017585:Ultrasonography, Doppler, Transcranial