Gutron treatment of patients suffering from essential orthostatic hypotony. Part Three--Hemodynamic-autonomic interactions.

: In this communication neurovegetative investigation of circulatory system in essential orthostatic hypotony (EOH) is continued. Our previous polycardiographic and heart rate variability (HRV) studies showed, that hemodynamic alterations in EOH are concerned with impairment of both branches of autonomic system. But hemodynamic-autonomic interactions in EOH are till now not well recognized. Therefore, in group of 9 patients (pts) with EOH we performed a study before and after midodrine (Gutron, Gu) 5 mg i.v. treatment. Sympathovagal balance, based on heart rate variability (HRV), was analysed in orthostatic trial. Hemodynamic parameters such as: heart rate (HR), systolic and diastolic blood pressure (RRs and RRd), as well as double product (DP) were measured in resting and after tilt. Simultaneously, on basis of computer-assisted tachograms standard deviation of 512 sinus cycles lengths (SD-SCL) was calculated and on basis of power spectral analysis by means of fast Fourier transform, the following variables: amplitudes (absolute powers) of high (aHF, 0.15-0.35 Hz) and low frequencies (aLF, 0.05-0.15 Hz) spectra, percentage powers of HF and LF spectra (%HF, %LF) and their ratio, named vegetative control coefficient (VCC, %LF:%HF). The results were compared to the control group (18 healthy volunteers). We found in EOH-pts significant correlation between aLF and resting HR, whereas after Gu this correlation disappeared and made the reaction of these pts similar to the control subjects, in which these correlations didn't appear. Resting RRs and RRd negatively correlated with aLF in controls, while in EOH-pts this relations were inverse i.e. positive.(ABSTRACT TRUNCATED AT 250 WORDS)