Baroreflex function in vasodepressive syncope: detection of early impairment.
BACKGROUND
Defective baroreflex function has been suggested as a potential mechanism accounting for the development of syncopal episodes. The present study was therefore aimed at assessing the non-invasive, indirect hemodynamic profile and baroreflex function by means of tilting, which is a natural stimulation crucial to physiological baroreflex activity, in syncopal patients and healthy controls.


METHODS
Seventeen consecutive patients with a positive response to head-up tilting and fourteen healthy subjects as controls underwent continuous and non-invasive beat-to-beat heart rate and arterial pressure measurements in order to evaluate systolic, diastolic, and dicrotic pressures, as well as heart rate. Baroreflex function was calculated as the slope of the linear regression line relating systolic arterial pressure to RR interval changes during upward and downward phases of tilting, respectively.


RESULTS
When compared to healthy subjects, vasodepressive patients showed a significantly weaker correlation between systolic pressure and RR interval changes both in upward tilting, (r = 0.68 vs r = 0.91, p<0.05) and downward tilting (r = 0.48 vs r = 0.93, p<0.01).


CONCLUSIONS
Our results show that an impairment in baroreflex-mediated adjustment to postural challenge can be detected in syncopal patients also during upward tilting, that is, in the early phase of the test. Moreover, our investigation emphases the utility of a noninvasive, complete hemodynamic evaluation of the early phase of tilting in order to detect peculiar behaviours of pulse wave contour and related parameters.
Franchi
Franco
F
Department of Internal Medicine, University of Florence School of Medicine, Florence, Italy. f.franchi@dfc.unifi.it
Lazzeri
Chiara
C
Romano
Salvatore M
SM
Toso
Anna
A
Chiostri
Marco
M
Foschi
Marco
M
Pistolesi
Massimo
M
Di Donato
Marisa
M
D000328:Adult; D017704:Baroreflex / Q000502:physiology*; D016022:Case-Control Studies; D003971:Diastole; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D019462:Syncope, Vasovagal / Q000209:etiology / Q000503:physiopathology*; D013599:Systole; D018667:Tilt-Table Test