[Comparison Clinical Data and Results of Mathematical Modeling in Radiofrequency Ablation of Permanent Atrial Fibrillation: Cardioversion Might Be the Final Stage in the Combined Treatment].

to compare the theoretical possibility of permanent atrial fibrillation (AF) elimination (on the model of the 6-wave re-entry) result.

[Approximation of mathematical scanning simulation data and clinical results f radiofrequency ablation of perimitral atrial flutter. Condition of existence of perimitral atrial flutter].

Aim: 1) to create Perimitral Atrial Flutter (PMAFL) model and estimate theoretical probability of elimination of perimital reetntry using left atrial geometry two-dimensional mathematical modeling and ablative formatting; 2) to compare clinical results of PMAFL ablation by means of mitral vs inferioseptal isthmus ablation and mathematical modeling data.

Material And Methods: Clinical phase. Study was conducted on 24 pts (6 women, 57.

[Comparison of the effectiveness of pulmonary veins isolation vs linear radiofrequency ablation in paroxysmal atrial fibrillation patients using either mathematical scanning or clinical approach].

Aim: to compare clinical results of linear ablation vs. PVI approach in patients with paroxysmal AF and to estimate theoretical probability of 4-waves re-entry to eliminate as a results of the both ablative techniques formatting by means left atrial geometry two-dimensional mathematical modeling.

Material And Methods: Clinical phase.

[Control of the unified heart rhythm].

The problem of the control of cardiac rhythm has been considered in terms of the general theory of the synchronization of relaxation systems. The main pathways of the control of cardiac rhythm have been determined: (1) control with regard for the features of synchronization of relaxation systems during the formation of the unified heart rhythm due to the acceleration of the slow diastole depolarization phase; (2) control by gradual integral increase in the duration of the slow diastole depolarization phase; (3) subsequent synchronization of the rhythm as a delay of the slow diastole depolarization phase. Possible applications of the mathematical simulation methods to study the mutual synchronization during the formation of the unified heart rhythm and synchronization for the effective control of the formed unified rhythm of the sinoatial node are considered.

[About the formation of the uniform rhythm in the sinoatrial node of the heart].

Dynamic processes during the establishment of the uniform heart rhythm have been considered. It was shown that, during the establishment of the uniform rhythm as a result of mutual synchronization, the establishment of phase parities and a delay of excitation occur. The establishment of the uniform rhythm in a system of cooperating pacemakers of relaxation oscillators was studied on various mathematical models of the sinoatrial node.

[A study of synchronization of the sinus unit upon stimulation from auricles].

The excitation of the sinoatrial unit from heart auricles of the frog has been studied. Potentials were recorded by means of microelectrodes inserted to pacemaker of the sinoatrial unit. It has been established that auricles can impart the rhythm to the sinoatrial unit due to electric and electromechanical influence, and electromechanical influence is of greater significance.

[Rhythmogenesis in the sinoatrial unit of the heart].

The most significant experimental data about the formation of a uniform rhythm of the sinoatrial unit of the heart for both the intact sinoatrial unit of the heart and cardiomyocytes in cellular structures are presented. The basic mathematical models for studying the processes of synchronization in the sinoatrial unit of the heart are described, including equations of Noble, Bonhoffer, and van der Pol and modified axiomatic models. The basic results obtained using the mathematical models are presented.

[Identification of nonlinear models of biological membranes by the method of fixed voltage].

A mathematical substantiation of the method suggested by Hodkin and Huxley in 1952 for the identification of nonlinear systems is presented. A procedure for the application of this method was developed, which involves creating the structure of a mathematical model, carrying out a series of tests with specially chosen signals, and finding the unknown parameters. The basic requirements to admissible sets of entrance and target signals and the operator of the system were determined.

[The interaction of homotypic and heterotypic embryonic stem cells with developing embryos].

It has been demonstrated that embryonic stem cells form adhesive contacts with external blastomeres of mouse morula, while there is no such contact with blastocysts. The development of morula in the blastocysts is delayed inside a dense layer of such cells; however, in some cases, external blastomeres of the morula begin to differentiate into trophoblastic cells. The introduction of an excessive number of embryonic stem cells (15-20) into a 4-8-cell embryo results in abnormal development.

[Role of juvenile hormone metabolism in the adaptation of Drosophila populations to stressful environmental conditions].

The effect of heat stress on the system of degradation of juvenile hormone (JH) and on fertility of Drosophila virilis and D. melanogaster was studied. In wild-type strains of both species, stress resulted in delay of oviposition and in a decrease in JH hydrolysis and fertility, which lasted for several days after heat treatment.

A comparative analysis of juvenile hormone metabolyzing enzymes in two species of Drosophila during development.

The course of changes in the activities of enzymes degrading juvenile hormone (JH), epoxyde hydrolase (JHEH) and JH-esterase (JHE) was studied in two lines of Drosophila virilis (101 and 147) and in two lines of D. melanogaster (Canton-S and 921283). It was established for D.

[The synchronizing interaction and mechanism of the formation of the common rhythm of the cardiac pacemaker. I. The modeling of the interaction of 2 pacemaker elements].

The main physiologic hypotheses in establishing a common rhythm of the heart sino-atrial node (SAN) have been considered. A mathematical model of SAN which takes into account the interaction between pace-makers in pairs has been proposed. A quantitative description of common rhythm establishing taking into account interaction in pairs has been obtained, the expressions for the period of common rhythm, a delay and the rate of stimulation distribution have been found.

[A mechanism for setting a single rhythm for a multipacemaker sinoatrial node].

Interaction of the system of n pacemaker cells modelling the work of the heart sinoatrial node was studied. Suggesting the interaction additivity an expression was obtained for the system single rhythm. Dependence of the system single rhythm and propagation velocity of excitation delay on the number of pacemakers of the leading centre and connection force between the pacemakers was investigated.

[The mechanism of setting the common rhythm of the pacemaker pair in the sinoatrial node].

Principal physiological hypotheses concerning the setting of united rhythm in the heart sinoatrial node (SAN) are considered. A mathematical model of SAN is proposed which takes into account properties of individual elementary pacemakers and their interaction. Assuming paired interaction of the pacemakers there are revealed the main P.

[Effect of an anomalous broadening of the synchronization band after electric stimulation of heart tissues].

Synchronization effects of the second order induced by a change of the action potential (AP) shape in relation to the frequency of periodic stimulation were studied. Mechanism of anomalous increase of the synchronization band at periodic stimulation of the heart fibers was explained. By means of a modified method of synchronization diagrams the synchronization bands were calculated for possible stimulation regimes taking into account a change in RP shape and dynamic threshold (DT) depending on the frequency of the initiated regimes.

[Kinematics of crawling locomotion. I. Ideal elastic model].

One-dimensional model of polysegmental ideal-elastic body is considered, movements of which in the free state are described by wave equation. Regimes of creeping without the loss of initial energy are examined, when the moments of attachment of the segment boundaries to the substrate are synchroneous with instantaneous stopping of free oscillations. Possibility of the existence of two coordination patterns--unconcerted and concerted metachrony is shown.