Heart rate variability in patients with neurocardiogenic syncopes

Abstract

AIM: To investigate chronotropic heart regulation and prognostic significance of heart rate variability (HRV) in patients with neurocardiogenic syncopes (NCS). MATERIAL AND 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. CONCLUSION: 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.