Do subjects with vasovagal syncope have subtle haemodynamic alterations during orthostatic stress?

Aims: 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.

Methods And 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.