Looking for changes in the heart rate of patients with Neurocardiogenic Syncope

Neurocardiogenic Syncope (NCS) is a temporary loss of consciousness due to a global cerebral hypoperfusion caused by bradycardia and/or significant hypotension. We analyzed the heart rate variability (HRV) of three groups during the Tilt-test, in the supine and standing position, before hypotension. The groups are: 1) 17 healthy individuals, 2) 18 patients with complaint of NCS, but a negative Tilt-test and 3) 16 patients with complaint of NCS and a positive Tilt-test. There is no significant difference for age and anthropometric characteristics among groups (5%). We did multifractal analysis by the MFDFA technique. We estimated, also, the Largest Lyapunov Exponent (LLE), using the Rosenstein algorithm. The loss of multifractality, as well as a decrease in the LLE, imply less complex system. The multifractal analysis showed no difference among groups, in both the supine and in the standing position (5%). However, compared to LLE, there are differences among groups, in the standing position, but not in the supine. There is significant difference between the supine and standing position for all groups. Most notably, the LLE for groups 2 and 3 are lower than for the group 1. In addition, groups 2 and 3 are equal. We conclude that in the standing position, there is a reduction of complexity of the HRVfor patients with NCS (5%).