[Tilt training increases vasoconstrictor reserve in patients with neurocardiogenic syncope].
Neurocardiogenic syncope (NCS) is a common clinical entity resulting from an excessive reflex autonomic response, particularly during orthostatism. Treatment options are controversial and of limited effectiveness. Tilt training (TT) is a promising option to treat these patients. However, its mechanism of action and clinical impact remain unclear.


OBJECTIVE
To characterize hemodynamic and autonomic responses during a TT program in patients with NCS refractory to conventional measures.


METHODS
We studied 28 patients (50% male, mean age 41±14 years) without structural heart disease, with NCS documented by tilt testing. The TT program included 9 tilt sessions (3 times a week, 30 min) (60° - 6 sessions, 70° - 3 sessions), under ECG and blood pressure monitoring combined with home orthostatic self-training and 10° head-up during sleep. Systolic volume, cardiac output, total peripheral resistance, baroreflex sensitivity and heart-rate variability were computed. Patients were reassessed at 1 month and every 6 months for a maximum of 36 months (24±12 months).


RESULTS
Over the course of the TT program there was a significant increase in total peripheral resistance (1485±225 vs. 1591±187 dyn·s·cm(-5), p<0.05), with a decrease in standard deviation (206±60 vs. 150±42, p<0.05). During follow-up, syncope recurred in five patients (19%), with a significant reduction in the number of episodes (4.0±3.2/patient in the 12 months before TT vs. 1.4±0.8/patient post-TT, p<0.05).


CONCLUSIONS
In refractory NCS, TT may be an effective therapeutic option, with long-term benefits. These results appear to be due to an increase in vasoconstrictor reserve combined with a reduction in its variance.
Instituto de Fisiologia e Unidade de Sistema Nervoso Autónomo, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal. sergiolaranjo@gmail.com
Sérgio
S
Laranjo
Mário
M
Martins Oliveira
Cristiano
C
Tavares
Vera
V
Geraldes
Sofia
S
Santos
Eunice
E
Oliveira
Rui
R
Ferreira
Isabel
I
Rocha
D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019462:Syncope, Vasovagal / Q000503:physiopathology*; D018667:Tilt-Table Test; D014661:Vasoconstriction; D055815:Young Adult