[Electrical and magnetic fields of the elementary bioelectric generator in the bounded anisotropic myocardium]. / Elektricheskoe i magnitnoe polia élementarnogo bioélektricheskogo generatora v anizotropnom ogranichennom miokarde.

Using the equations of electrodynamics of stationary currents, relationships were derived for calculating the characteristics of electric and magnetic fields of an elementary (dipole) bioelectric generator in a heterogeneous medium consisting of two regions namely, an anisotropic conducting region corresponding to the excitable myocardium tissue and an isotropic conducting or dielectric region corresponding to the space outside the myocardium where the measurement is made. The shape of distributions of the electric potential and magnetic induction at the myocardium surface was determined, and the effect of anisotropy on these distributions was estimate. Formulas for the identification of the local excited zone within the myocardium from electric and magnetic measurements outside the excitable tissue or on its surface were obtained.

[Electric and magnetic fields of the closed depolarization front in the anisotropic myocardium]. / Elektricheskoe i magnitnoe pole zamknutogo fronta depoliarizatsii v anizotropnom miokarde]

On the basis of the bidomain model of anisotropic myocardium, mathematical relationships for calculating the characteristics of the extracellular electric and magnetic fields outside a closed or open depolarization front were derived on the assumption that the generator and fields are axially symmetric with respect to the longitudinal direction of the fibres making up the excitable tissue. The spatial configuration of the fields was determined and quantitative estimates were obtained for the electric potential and magnetic induction caused solely by the macroscopic anisotropy of the myocardium tissue as a volume conductor.

[An elementary bioelectrical generator of the anisotropic homogeneous myocardium and its extracellular field]. / Elementarnyi bioelektricheskii generator anizotropnogo odnorodnogo miokarda i ego vnekletochnoe pole.

On the basis of the bidomain model that takes into account the electric anisotropy of body tissues, analytical relationships were developed for calculating the characteristics of electric and magnetic fields produced by an elementary (dipole) bioelectric generator that arises in the electrogenic excitable tissue of the myocardium. The errors in the identification of intensity and location of the bioelectric generator in the myocardium were estimated from the measurements of its external fields (noninvasive identification of the excited region) using approximate methods based on isotropic models of the physical medium.

[A model of spherical quasi-epicardium for mapping of the electrical potential of the heart]. / Model' sfericheskogo kvasiépikarda dlia otobrazheniia élektricheskogo potentsiala serdtsa.

Possibility of determination of the heart electric potential maps on the spherical quasiepicardium from the body surface potentials measured by means of multiple leads, is estimated. The simplified models of ventricular depolarization electric generator considered in this study, consist of sets of uniform double layers representing basic configurations of the true electric generator of the heart, while allowing an analytical calculation of the multipole components, as well as potential of the generator. The contribution of the generator multipole components to the potential on the spherical quasiepicardium is evaluated. The results of the study show that it is reasonable to use the multipole components up to the 3rd order for noninvasive mapping of the potential on the spherical quasiepicardium with the radius which provides tangential touching of the quasiepicardium with the precordium surface. Because of bringing the potential observation region nearer to the generator and improving concentricity of this region with respect to the generator, the quasiepicardium mapping technique allows revealing much more complicated generator configurations than those found out by straightforward estimation of the potential measured on the chest surface, thereby facilitating more accurate noninvasive recognition of the heart electrophysiological state.

Decarto technique in long-term observation of patients treated for primary pulmonary hypertension.

Techniques for noninvasive observation of heart states play an important part in experimental and therapeutic cardiology. The objective of this work is to describe a new method for intelligible pictorial representation of data acquired by an orthogonal electrocardiographic lead system and demonstration of possibilities of this method in estimating the results of longterm treatment for a cardiac disease. The method used, dipole electrocardiotopography (DECARTO), provides a set of maps (decartograms) that depict in an explicit form the instantaneous, as well as integral electrophysiological properties of the heart during the excitation cycle. The observed group of patients contained 10 females and 2 males with primary pulmonary hypertension. It was found that in all but one cases tested, the features of the maps strongly correlated with the results of the other diagnostical methods and clinical findings. The trends to improvement (6 cases), stabilization (4 cases), or deterioration (1 case) of the heart state were clearly indicated. In one case, however, the interpretation of the decartograms was ambiguous. The advantage of the DECARTO technique lays in clearness of data representation for visual analysis and facilitation of electrophysiological and anatomical interpretation of the data. (Fig. 6, Ref. 2)

[The functional and sonographic parallels in chronic pancreatitis]. / Funktsional'no-sonograficheskie paralleli pri khronicheskom pankreatite.

Ultrasonic histogramme was studied in 35 patients with chronic pancreatitis and 20 donors, taken in the area of the head and body of the pancreas, as were levels of immunoreactive trypsin--fasting and after standard food load,--and C-peptide in blood serum on an empty stomach. To increase informative value and specificity of ultrasonic and radioimmunologic investigations an index has been suggested, based on the findings from histogramme and radioimmunity analysis.