Do subjects with vasovagal syncope have subtle haemodynamic alterations during orthostatic stress?
OBJECTIVE
There are conflicting reports on the presence of subtle haemodynamic alterations during orthostatic stress in subjects with vasovagal syncope (VVS). The aim of the present study was to investigate whether young/middle-aged subjects with VVS show abnormal responses to orthostatic stress.


RESULTS
Four groups of subjects underwent tilt testing (TT) during the passive phase and, if negative, after nitroglycerin administration: Group I, 20 subjects with a history of syncope and positive passive TT; Group II, 23 subjects with a history of syncope and TT positive after nitroglycerin; Group III, 23 subjects with a history of syncope and negative TT; and Group IV, 20 normal control subjects. Heart rate, systolic, diastolic, and mean blood pressure, stroke volume, cardiac output, and total peripheral resistance were computed from pressure pulsations (Modelflow). The demographic data and the values of the haemodynamic variables in the supine position did not differ significantly among the four groups. The per cent changes in these variables did not differ significantly among the four groups after 2 and 5 min of TT and among Groups II, III, and IV, 2 min after nitroglycerin administration.


CONCLUSIONS
Young/middle-aged subjects with VVS have a normal measured haemodynamic response to orthostatic stress; therefore, the vasovagal reflex is not secondary to an impairment of the primary vasoconstrictive mechanism.
Fucà
Giuseppe
G
Division of Cardiology and Arrhythmologic Centre, Ospedale Civile, 44042 Cento (FE), Italy.
Dinelli
Maurizio
M
Gianfranchi
Lorella
L
Bressan
Sabrina
S
Lamborghini
Catia
C
Alboni
Paolo
P
D000328:Adult; D001783:Blood Flow Velocity; D001794:Blood Pressure; D004244:Dizziness / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019462:Syncope, Vasovagal / Q000503:physiopathology*; D018667:Tilt-Table Test / Q000379:methods*