Tese
Análise de substâncias vasoativas antes e durante o teste de inclinação em pacientes com Sincope Vasovagal (Estudo pareado por sexo e idade) e qualidade de vida após o diagnóstico de Resposta Neurorreflexa pelo teste de inclinação
Fecha
2022-01-21Registro en:
0000000176582076
000000020963948X
Autor
CLAUDIA MADEIRA MIRANDA
Institución
Resumen
Background: vasovagal syncope (VVS) is the most common cause of syncope. Some stages
of its pathophysiological mechanisms remain unclear. Vasoactive substances such as nitric
oxide metabolites (NOx) and endothelin (ET) may be involved during acute orthostatic stress.
Objective: to analyze plasma changes in NOx and ET and heart rate variability (HRV) in the
supine positions (T1) and during the head-up tilt test (HUTT) (T2), in patients with VVS
(case group) and control group.
Methods: Thirty-seven patients (17 in the case group and 20 in the control group), matched
for age and sex (mean aged 31.8 years) underwent HUTT with simultaneous HRV recording
and venipuncture.Blood samples were collected during phases T1 and T2 and the analysis was
performed without knowledge of the HUTT result.
Results: in the total sample, there was an increase in NOx values (p=0.014), however there
was no increase in ET values from phase T1 to phase T2. Patients with VVS tended to
increase plasma NOx values (p = 0.057) and had significantly higher plasma values compared
to ET (p= 0.033) between phases T1 to T2. In the control group, there was no significant
change in the values of these vasoactive substances. Regarding HRV, there were a decrease in
the component HF (high frequency) and increased of the LF (low frequency)/HF ratio during
HUTT.
Conclusions: There was an increase in ET during HUTT occurred only in the case group. These patients are
more likely to have an imbalance between antagonistic vasoactive biomarkers during
orthostatic stress.