Saratov JOURNAL of Medical and Scientific Research

Karavaev A.S.

Saratov State University n.a. N.G. Chernyshevsky, Faculty of Nano- and Biotechnologies, Assistant Professor, Candidate of Physical and Mathematical Science

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

Year: 2018, volume 14 Issue: №1 Pages: 45-49
Heading: Internal Diseases Article type: Short message
Authors: Kiselev A.R., Vulf K.A., Shvartz V.A., Karavaev A.S., Borovkova E.l., Bockeria O.L.
Organization: Bakulev Center of Cardiovascular Surgery, Saratov State Medical University n.a. V.I. Razumovsky Research Institute of Cardiology, Saratov state university
Summary:

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.

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

Year: 2016, volume 12 Issue: №4 Pages: 541-548
Heading: Physiology and Pathophysiology Article type: Original article
Authors: Karavaev A.S., Runnova A.E., Borovkova E.l., Ishbulatov Y.M., Khorev V.S., Kiselev A.R., Zhuravlev M.O., Ponomarenko V.I., Prokhorov M.D., Bezruchko B.P., Koronovsky A.A..
Organization: Saratov Branch of Institute of Radio Engineering and Electronics n.a. V.A. Kotelnikov, Saratov State Medical University, Saratov state university
Summary:

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.

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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

Year: 2015, volume 11 Issue: №4 Pages: 537-542
Heading: cardiac surgery Article type: Original article
Authors: Shvartz V.A., Karavaev A.S., Borovkova E.l., Mironov S.A., Ponomarenko V.I., Prokhorov M.D., Butenko A.A., Gridnev V.I., Kiselev A.R.
Organization: Saratov state university, Saratov Institute of Cardiology, Russia, Saratov Branch of Institute of Radio Engineering and Electronics n.a. V.A. Kotelnikov, Bakulev Center of Cardiovascular Surgery
Summary:

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.

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Evaluation of five-year risk of lethal outcome and development of cardiovascular disorders in patients with acute myocardial infarction on basis of 0.1-Hz rhythms synchronization in cardiovascular system

Year: 2010, volume 6 Issue: №2 Pages: 328-338
Heading: Internal Diseases Article type: Original article
Authors: KiselevA.R., Gridnev V.I., KaravaevA.S., O.M. Posnenkova., V.I. Ponomarenko., M.D. Prokhorov., B.P. Bezruchko.,V.A. Shvartz
Organization: Saratov National Research University n.a. N. G. Chernyshevsky, Saratov Institute of Cardiology, Russia, Saratov Branch of Institute of Radio Engineering and Electronics n.a. V.A. Kotelnikov
Summary:

The research goal is to evaluate the impact of autonomic heart control indices on five-year risk of lethal outcome and development of cardiovascular disorders in patients with acute myocardial infarction (AMI) and to study the dynam¬ics of indices in short- and long-term period. 125 patients with AMI (42% female), ages 30 to 83 years, were enrolled in prospective observational study. Observation period lasted 6 years. Control checking was carried out in 1 week, 3 weeks, 6 months, 1 year and then annually. The dynamics of heart rate variability (HRV) and the synchronization of 0.1-Hz rhythms of heart and microcirculation (S) were studied during the first year. Outcomes proved to be death, MI, stroke. Development of acute heart failure Killip 2-4 and indices S < 20% during the first week of AMI (х2 = 10,5, p = 0,005 for the Cox model) played a significant role in evaluation of five-year risk of death after AMI. Sensitivity (Se) and specificity (Sp) of index S < 20% during the first week of AMI were 76% and 43% correspondingly. The Cox model showed that indices of HRV and 0.1-Hz rhythms synchronization were not of great value in evaluation of five-year risk of death after AMI. The article concludes that indices S < 20% in patients with AMI possess better prognostic value than common clinical parameters

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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

Year: 2010, volume 6 Issue: №1 Pages: 061-072
Heading: Internal Diseases Article type: Original article
Authors: A.R. Kiselev, A.S. Karavaev, V.I. Gridnev, O.M. Posnenkova, V.A. Shvartz, V.I. Ponomarenko, M.D. Prokhorov, B.P. Bezruchko
Organization: Saratov National Research University n.a. N. G. Chernyshevsky, Saratov Institute of Cardiology, Russia, Saratov Branch of Institute of Radio Engineering and Electronics n.a. V.A. Kotelnikov
Summary:

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 treatment

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