Patent RU-2696072-C1 (RU)
Title: Method for detecting and predicting the moment of separation of an atherosclerotic formation and a device for its implementation
Inventor: Zakirzhanov Nail Rinatovich
IPC: A61B8/00
Filed: 2018-10-15
Granted: 2019-07-30
Abstract: FIELD: medicine. 
     SUBSTANCE: group of inventions refers to medicine, namely to vascular surgery, and can be used in making decisions on the possibility of surgical intervention in preventing patients with acute cerebrovascular disorders. Disclosed is an apparatus for realizing a method of detecting and predicting the moment of separation of an atherosclerotic formation, through which by means of an ultrasonic duplex scanner a value of local blood flow velocity is obtained, its biophysical parameters, structure and morphology of atherosclerotic formation is determined, delineation of base and frontal surface of atherosclerotic formation. Additionally, a series of consecutive multiple measurements of local blood flow velocity in a longitudinal section of a vessel before and after an atherosclerotic formation and in a zone of its least lumen during observation time, which are then mathematically processed by averaging over time the current blood flow velocity values. That is followed by constructing a diagram of blood flow velocities distributed along the vessel axis within a vessel within the observable area. Then, in compliance with equations of hydrodynamics of liquid flow in vessel, distributed pressure is determined along axis of observed portion of vessel and its diagram is plotted within the limits of length of considered section of vessel, based on which plaque is detached from force Y in radial direction, as well as force of front drag X exerted by blood flow on atherosclerotic formation in axial direction. Thereafter, the obtained values of the active forces acting on the atherosclerotic formation are compared with their allowable reaction force values, which are determined by friction forces F fr  and adhesion F ad  it with a vessel. If these inequalities are satisfied, another pair of conditions for exceeding values of ratios of active forces X and Y to reaction forces F fr  and F ad  respectively in axial and in radial directions above given numerical values of threshold values h X  and h Y , corresponding to maximum permissible values from the point of view of detection of separation moment ASF. Further, based on time scanning of pressure drop from array of data of series of consecutive and equidistant by time multiple measurements of blood flow velocity, obtained in proximal section of vessel with atherosclerotic formation, by recalculation dependence gives average value of rate of change of axial pressure ṗ ax  for entire series of successive measurements. Further, based on the temporal sweep of the pressure drop from the array of serial and equidistant by time measurements of the blood flow velocity obtained in the central section of the vessel with the atherosclerotic formation, by recalculation dependence is obtained averaged value of change rate of radial pressure ṗ rad  for the entire series of sequential measurements with respect to the pressure drop in the proximal section of the atherosclerotic formation defined by the drag c x  ASF, to rate of pressure change in axial direction ṗ ax  determining time interval T ax   ex , defining moment of separation ASF in axial direction. Then in relation to pressure drop in central section to rate of pressure change in radial direction ṗ rad  determining time interval T rad   ex , defining moment of separation ASF in radial direction. That is followed by determining the shortest time interval, which is the prediction time of the moment of separation of the atherosclerotic formation. 
     EFFECT: group of inventions provides determining the necessity and priority of the surgical management according to the predicted proximity of the separation moment ASF with high reliability of its determination; at that, by ASF method includes capturing an unstable fragment ASF blood flow. 
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