Hemodynamic mechanisms underlying prolonged post-faint hypotension.
Clin Auton Res
; 21(6): 405-13, 2011 Dec.
Article
em En
| MEDLINE
| ID: mdl-21796352
ABSTRACT
OBJECTIVE:
During hypotension induced by tilt-table testing, low presyncopal blood pressure (BP) usually recovers within 1 min after tilt back. However, in some patients prolonged post faint hypotension (PPFH) is observed. We assessed the hemodynamics underlying PPFH in a retrospective study.METHODS:
Seven patients (2 females, aged 31-72 years) experiencing PPFH were studied. PPFH was defined as a systolic BP below 85 mmHg for at least 2 min after tilt back. In 6 out of 7 presyncope was provoked by 0.4 mg sublingual NTG, administered in the 60° head-up tilt position following head-up tilt for 20 min. Continuous BP was monitored and stroke volume (SV) was computed from pressure pulsations. Cardiac output (CO) was calculated from SV × heart rate (HR); and total peripheral resistance (TPR) from mean BP/CO. Left ventricular contractility was estimated by dP/dt (max) of finger pressure pulse.RESULTS:
Systolic BP (SYS), diastolic BP (DIAS) and HR during PPFH were lower compared to baseline SYS 75 ± 14 versus 121 ± 18 mmHg, DIAS 49 ± 9 versus 71 ± 9 mmHg and HR 52 ± 14 versus 67 ± 12 beats/min (p < 0.05). Marked hypotension was associated with a 47% fall in CO 3.1 ± 0.6 versus 5.9 ± 1.3 L/min (p < 0.05) and decreases in dP/dt, 277 ± 77 versus 759 ± 160 mmHg/s (p < 0.05). The difference in TPR was not significant 1.1 ± 0.3 versus 1.0 ± 0.3 MU (p = 0.229). In four patients, we attempted to treat PPFH by 30° head-down tilt. This intervention increased SYS only slightly (to 89 ± 12 mmHg).INTERPRETATION:
PPFH seems to be mediated by severe cardiac depression.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Síncope
/
Hemodinâmica
/
Hipotensão
Tipo de estudo:
Observational_studies
/
Risk_factors_studies
Limite:
Adult
/
Aged
/
Female
/
Humans
/
Male
/
Middle aged
Idioma:
En
Ano de publicação:
2011
Tipo de documento:
Article