Comparison of dynamic of autonomic control indices in cardiovascular system under the treatment by ACE inhibitor (Enalapril) and beta-blocker (Metoprolol) in patients with hypertension

The objective of the present research was to compare the influence of Enalapril and Metoprolol on synchronization of 0.1 Hz-regulation of heart and blood microcirculation. 42 patients aged 49±9 years old with hypertension I, II were included in the study. 0.1 Hz-oscillations in heart rate variability (HRV) and blood microcirculation were registered during the passive orthostatic sign while breathing spontaneously. The duration of each test was 10 minutes. Synchronization was estimated as a phase difference between 0.1 Hz-rhythms in heart rate and in filling of blood microcirculation. Quantitative measures of synchronization were also estimated. In addition frequency values of HRV spectrum in LF- and HF-ranges were assessed. Enalapril and Metoprolol had comparable effect on blood pressure reduction. Treatment with both Enalapril and Metoprolol in patients with significant vegetative dysfunction resulted in repair of functional interaction between 0.1 Hz-regulation of heart and blood microcirculation. Enalapril was preferred in hypertensive patients with prevalence of disorders of vegetative regulation of blood microcirculation. Metoprolol influenced positively on 0,1 Hz-rhythm synchronization in patients with predominance of heart vegetative regulation dysfunction and in patients with sympathicotonia. In patients with hypertension and initially normal level of synchronization of 0.1 Hz-mechanisms treatment with Enalapril or Metoprolol caused functional dissociation. Differentiated approach to the choice of hypertensive therapy should consider individual peculiarities of system vegetative dysfunction. The level of synchronization of 0.1 Hz-rhythms in cardiovascular system should especially be evaluated initially and during the treatmen

Comparative evaluation of autonomic regulation of circulation in patients undergone coronary artery bypass grafting or correction of acquired valvular heart disease

The aim of the research was to study the peculiarities of vegetative regulation of blood circulation in cardiac surgery patients who underwent coronary artery bypass grafting (CABG) or correction of acquired valvular heart disease (CAVHD). Material and Methods. In this study we included 42 patients (12 women; 63 (57; 67) years), who underwent CABG, and 36 patients (16 women; 58 (47; 65) years) who underwent CAVHD. The synchronous 15 minutes records of electrocardiogram and photoplethysmogram (PPG) were performed in all patients before and after surgery. Time domain and frequency domain measures of heart rate variability (HRV) and index of synchronization between low-frequency (LF) oscillations in HRV and PPG (index S) were analyzed. Results. Most studied autonomic indices did not have statistically significant differences between patients with CABG and CAVHD in the study stages, except for heart rate, which was higher in patients before CAVHD (p=0,013). Conclusion. The values of HRV and index S do not depend on the difference in the clinical status and the features of performed cardiac surgical interventions between patients with CABG and CAVHD.</p

Synchronization of low-frequency oscillations in the cardiovascular system: Application to medical diagnostics and treatment

We investigate synchronization between the low-frequency oscillations of heart rate and blood pressure having in humans a basic frequency close to 0.1 Hz. A quantitative estimation of this synchronization based on calculation of relative time of phase synchronization of oscillations is proposed. We show that assessment of synchronization between the considered oscillations can be useful for selecting an optimal dose of beta-blocker treatment in patients after acute myocardial infarction. It is found out that low value of synchronization between the low-frequency rhythms in heart rate and blood pressure at the first week after acute myocardial infarction is a sensitive marker of high risk of mortality during the subsequent 5 years

Investigation of statistical characteristics of interaction between the low-frequency oscillations in heart rate variability and peripheral microcirculation in healthy subjects and myocardial infarction patients

Objective. This study compares the statistical characteristics of interaction between 0.1 Hz oscillations in heart rate variability (HRV) and photoplethysmogram (PPG) in healthy subjects and myocardial infarction (Ml) patients. Material and methods. We studied 23 healthy subjects (20 men and 3 women aged 26±3 years) and 23 patients (12 men and 11 women aged 52±4 years) at about one month after Ml. The 10-minute signals of simultaneously recorded cardioin-tervalogram (CIG) and PPG were studied. We calculated the total percentage of phase synchronization between the studied 0.1 Hz oscillations and estimated the distribution functions of duration of synchronous and non-synchronous epochs, the variability of basic frequency of oscillations, and variance of phase noises in 0.1 Hz oscillations in HRV and PPG. Results. The total percentage of phase synchronization between 0.1 Hz oscillations is significantly greater in healthy subjects than in Ml patients (47±3% and 26±4%, respectively). Significant difference between these two groups in the distribution of duration of synchronous and non-synchronous epochs was not revealed. The Ml patients had greater variance between the basic frequencies of 0.1 Hz oscillations in HRV and PPG than healthy subjects. This phenomenon correlates with the increased level of phase noises in the records of Ml patients. Conclusion. The quality of synchronization between 0.1 Hz oscillations in HRV and PPG is associated with the strength of influence of external factors (noises) and variability of the basic frequency of these oscillations

Synchronization of low-frequency rhythms in electroencephalogram by respiration with linear dependent time frequency.

The aim of the present study was to investigate the features of interaction of low-frequency rhythms in delta band of electroencephalogram (EEG) and processes in vegetative regulation of circulation with respiration. Materials and methods. 19 leads of EEG, photoplethysmogram (PPG) and respiration were simultaneously recorded in four healthy males (19-25 years old) during 30 minutes physiological test with linearly increasing frequency of respiration. Modern methods of nonlinear dynamics were used to diagnose the presence of phase and frequency synchronization between respiration and low-frequency rhythms in delta band of EEG and in PPG. Results. We found significantly long sections of synchronization of delta rhythms in cervical leads of EEG and low-frequency rhythms in PPG by respiration with linearly increasing frequency. Conclusion. Obtained results correlate well with established hypothesis which suggest that low-frequency rhythms in baroreflectory regulation of circulation are in complex dynamic relationships with structures of brain stem. A method was proposed for quantitative evaluation of synchronization strength between respiration and low-frequency rhythms in electrical brain activity in physiological tests with respiration with frequency linearly increasing in time