[Analysis of ECG in ventricular fibrillation in man and animals based on chaos theory]. / Analiz EKG pri fibrilliatsii zheludochkov u cheloveka i zhivotnykh na osnove teorii khaosa.

The methods of the chaos theory were used to estimate the degree of irregularity of ventricular fibrillation in human and experimental animals. To verify the hypothesis that the degree of chaos depends on the species of the living organisms, the parameters characterizing the degrees of irregularity of ventricular fibrillation were estimated and compared. The comparative analysis was performed using 32 fragments of electrocardiographic records from five patients with sudden ventricular fibrillation bouts and 215 episodes of induced fibrillation in 17 animals. It was shown that fibrillation in human and animals has a different degree of regularity and different values of the chaotic component. The highest values of chaos were recorded in dogs, the lowest degree of chaos was observed in human. Rabbits and rats are intermediate, between dogs and humans. The fractuality of the structure-function organization of myocardium is discussed.

[Effect of emotional stress on the cardiac rhythm variability in rats]. / Vliianie émotsional'nogo stressa na variabel'nost' serdechnogo ritma u krys.

A degree of irregularities of the heart rhythm was studied by two methods: chaos-analysis and the HRV (heart rate variability) analysis. Our study shows an individual response in 3 groups of animals: 1--animals with low initial level of chaos (correlation dimension (PD2 < 2); 2--animals with high level of chaos (PD2 > 4); and animals with middle level of chaos (2 < PD2 < 4). The first two groups proved to be more sensitive to stress than the third group. Moreover we found that the electrical stability of the heart as measured by the fibrillation threshold, was higher for the chaos third group. The animals of the first two groups had low cardiac stability and high risk of stress-induced cardiac disturbances.

[Nitrogen monoxide in the mechanisms of cardiovascular functional resistance to emotional stress]. / Monooksid azota v mekhanizmakh ustoichivosti serdechno-sosudistykh funktsii pri émotsional'nom stresse.

The paper presents the results of examination of the mechanisms of development of different physiological dysfunctions (diminished cardiac electrical stability, fibrillation threshold fall) under emotional stress. Search was made for their drug correction (nitric oxide precursor L-arginine, the NO synthase blocker Ng-methyl-L-arginine and sodium nitrate). Experiments have indicated that L-arginine and sodium nitrate restore cardiac electrical stability. The normalizing effects of NO donors depended on the stage of cardiac disorders.

[Atrial fibrillation as the nonstationary process: analysis of chaotic dynamics]. / Fibrilliatsiia zheludochkov kak nestatsionarnyi protsess: metod analiza khaoticheskoi dinamiki.

A method for the mathematical analysis of recordings of the myocardium electrical activity during ventricular fibrillation is proposed. The method is based on evaluating the indices of the orderliness of the process. The entropy was one of the indices used. The analysis of EGG during ventricular fibrillation (an acute experiment on rats) revealed certain regularities in the apparently chaotic process of fibrillar oscillations. The entropy increased at the first stages of the fibrillation and then reached its maximal level. A gradual decrease in the entropy level preceded the spontaneous termination of fibrillation. This indicates that different stages of the process the degree of its disorganization changes. Upon spontaneous termination of fibrillation, quantitative changes transfer to qualitative changes. This reflects the transition of the myocardial system to another level of structural and functional organization.

[The role of delta-sleep-inducing peptide in the normalization of cardiac electric stability in experimental emotional stress]. / Rol' peptida delta-sna v normalizatsii elektricheskoi stabil'nosti serdtsa pri éksperimental'nom émotsional'nom stresse.

In chronic experiments on rabbits, a delta-sleeping inducing peptide was tested for effects on the cardiac electric stability and onset of ventricular premature beats during experimental emotional stress. The peptide in a dose of 60 nm/kg was found to normalize the thresholds of ventricular fibrillation and its predictors and to decrease or abolish spontaneous ventricular premature beats occurring during the stress. This suggests that the delta-sleep-inducing peptide may be used to prevent cardiac arrhythmias during stresses.

[Effect of delta-sleep inducing peptide on electrical instability of the heart in emotional stress]. / Vliianie peptida del'ta-sna na élektricheskuiu nestabil'nost' serdtsa pri émotsional'nom stresse.

The effect of the delta-sleep inducing peptide (DSIP) on disorders of the cardiac rhythm in emotional stress was studied in experiments on rabbits. DSIP (60 nmol/kg) diminished or arrested ventricular extrasystole occurring in experimental emotional stress. It was shown that the antiarrhythmic effect of DSIP is most manifest if it is injected just before exposure to the stress factors. DSIP injection induces increase of the thresholds of the occurrence of ventricular fibrillation and its precursors in intact animals. This can explain the high preventive effect of DSIP in stress. The acquired data on the antiarrhythmic effect of DSIP should be taken into consideration in elaborating preventive recommendations aimed at raising the organism's stability to stress factors.

[Parasympathetic regulation of cardiac rhythm in delta sleep-inducing peptide deficiency]. / Parasimpaticheskaia reguliatsiia serdechnogo ritma v usloviiakh defitsita peptida del'ta-sna v organizme.

The effect of delta-sleep peptide (DSP) deficiency on the parasympathetic regulation of the heart rate was studied on 35 rabbits. It was established that the injection of an-serum (titer-1:2000-1:3000) leads to the attenuation of parasympathetic influences: heart rate increase in freely behaving animals and a decrease in negative chronotropic effect with direct vagus irritation. Antiserum, like DSP, administration causes practically no damage of the myocardial ultrastructure.

[Effect of the delta-sleep peptide on parasympathetic regulation of the cardiac rhythm]. / Vliianie peptida del'ta-sna na parasimpaticheskuiu reguliatsiiu serdechnogo ritma.

Effect of delta-sleep peptide (60 nM/kg) on the parasympathetic regulation of cardiac activity has been studied in the experiments on rabbits. It has been established that intravenous administration of this peptide to voluntary-behaving animals results in heart rate reduction by an average of 16%, that can be eliminated by atropine. Delta-sleep peptide has been demonstrated to intensify negative chronotropic effect in the case of directly irritated wandering nerve. The data obtained explain a protective effect of delta-sleep peptide on the heart under emotional stress.