[Heart rate variability in patients with neurocardiogenic syncopes].
OBJECTIVE
To investigate chronotropic heart regulation and prognostic significance of heart rate variability (HRV) in patients with neurocardiogenic syncopes (NCS).


METHODS
A total of 90 patients (25 healthy controls and 65 patients with documented HRV, mean age 33.9 +/- 17.4 years) were divided into 3 groups depending on an NCS type (cardioinhibitory, n = 18; vasodepressive, n = 25; mixed, n = 22). All the examinees have undergone a long-term passive head-up tilt table test with registration and analysis of HRV.


RESULTS
A cardioinhibitory NCS variant was characterized by slow heart rate (both at rest and test), increased mode amplitude--Amo (by 28, 1, 21, 6 and 46.8% at rest, tilt test, in rehabilitation, respectively), range of deviation (RD) (by 47, 1, 62, 5 and 52.9%, respectively). A simultaneous rise of indices characterizing activity of the sympathic and parasympathic parts of the autonomic nervous system led to the absence of significant differences of the integral parameters (Amo/RD; index of regulatory system tension) vs control. Still more marked changes in the indices of cardiovascular vegetative regulation were registered in a vasodepressive NCS, but the differences with the control were moderate. Vegetative tonicity and reactivity in mixed NCS represent an intermediate variant between cardioinhibitory and vasodepressory types.


CONCLUSIONS
In NCS patients circadian HRV was less than in the controls. The parasympathic tonicity prevails in all NCS types. Moreover, NCS is affected by episodes of activation of sympathico-adrenal system. Typical HRV in different NCS variants allows using this method for their diagnosis, prognosis and follow-up of the patients.
Abdrakhmanov
A S
AS
D000328:Adult; D016022:Case-Control Studies; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D010275:Parasympathetic Nervous System / Q000503:physiopathology*; D011187:Posture; D012815:Signal Processing, Computer-Assisted; D019462:Syncope, Vasovagal / Q000503:physiopathology*; D018667:Tilt-Table Test