On the Concentration of External Electric Field Intensity on the Internal Surfaces of Blood Vessels

Purpose: To show that connective tissue forming the inner surfaces of blood vessels can act as a concentrator of an external electric field. Material and methods: Previously, when studying the effects of electromagnetic fields and radiation on the human body, the SAR calculation method and the experimental method of tissue-equivalent phantom dummies were used. Their implementation usually assumed that the absorbing medium is homophase. At the same time, the effects associated with the fact that biological tissue is a mixture of components whose permittivities differ by tens of times, and the particle sizes of the phase components, as a rule, do not exceed one millimeter, were not taken into account. The article presents the results of developing a computer model that allows analyzing the uneven distribution of the electric field in such an object. Computational experiments were performed using the author’s program based on the finite element method. Results: The structure of tissue containing blood capillaries was simulated by matrix systems containing cylindrical inclusions, the cross-sections of which were characterized by round and rectangular shapes. Computer experiments were conducted to calculate the patterns of spatial distributions of the electric field strength. The values ​​of the permittivity of the matrix and inclusions, the relative sizes and mutual positions of the inclusions were varied. The processes were considered stationary and axisymmetric. It was found that if the external electric field is directed along the axis of the cylindrical capillary, the field strengths inside the capillary and in the surrounding tissue are close to each other. If the external field is directed perpendicular to the capillary axis, a significant (tens of times) concentration of tension occurs in the connective tissue surrounding the capillary. The results obtained can be used to analyze the effects of stationary electromagnetic fields on the human body, as well as electromagnetic waves whose length significantly exceeds the size of blood capillaries. It is noted that the endothelium, which performs a number of important physiological functions, falls into the area of ​​concentration of electric field intensity and heat generation power. Conclusion: The data obtained indicate that when analyzing the mechanisms of occurrence of pathological changes created by an electric field in living tissue, it is necessary to take into account that the internal surfaces of blood vessels are characterized primarily by an increased risk. Particular attention should be paid to areas in which vessels converge with each other. Further development of specialized computer programs and their implementation in clinical research practice is expected.