RU2727748C2 - Method for complex analysis of cardiovascular biomechanics - Google Patents

Abstract

FIELD: medicine; cardiology.SUBSTANCE: invention can be used to study biomechanics of cardiovascular system. Method is carried out as following. Patient is placed on a couch, blood pressure (BP) is measured, patient's data and BP indices are entered into the computer. Funnel is inserted and the amplitude of the apexcardiogram and the sphygmogram is recorded. Rheovasography (RVG) is recorded in parallel by applying electrodes on extremities. Results are transmitted to computer (1) by means of analogue-to-digital converter (ADC) (2) in real time. Simultaneously ECG is recorded in I lead. Calculating basic biomechanical parameters in each phase of cardiac and vascular cycle (duration, average and extreme speed, average and extreme acceleration, average and extreme power, operation) are carried out by preset program by computer. Complex analysis of all parameters of biomechanical curves enables differential diagnosis of the main cardiovascular diseases and monitoring of their dynamics.EFFECT: invention provides higher rate of cardiovascular biomechanics and improved quality of examination.1 cl, 7 dwg, 7 tbl

Description

The invention relates to medicine, namely to cardiology and to methods for studying the biomechanics of the cardiovascular system.

In Russia, as in the rest of the world, cardiovascular diseases are the leading cause of death. However, if in some Western states there is an increase in life expectancy, an improvement in the prognosis of cardiac patients, then for our country, unfortunately, an increase in the prevalence of arterial hypertension (AH), coronary heart disease (IHD) and, as a result, chronic heart failure (CHF) is characteristic ... In this regard, much attention is paid to methods of functional diagnostics of cardiovascular diseases, which make it possible to identify the earliest changes in hemodynamics and monitor the effect of the treatment.

The main methods of instrumental diagnostics of the state of the cardiovascular system today are electrocardiography (ECG), echocardiography (echocardiography) and ultrasound scanning (ultrasound dopplerography - USDG) of the vessels. Electrocardiography is indispensable for assessing the electrical processes in the heart, but with functional tests, its results are indirect. Ultrasound methods (echocardiography, USDG of vessels) make it possible to describe in detail anatomical changes and reveal functional disorders, but they require the use of expensive equipment and the participation of highly qualified personnel.

A method and a device for assessing the risk of cardiovascular complications is known from the existing prior art (patent RU 2508904, IPC А61В 5/02, А61В 5/04, А61В 5/145, publ. 03/10/2014), according to which finger eponychia by optical capillaroscopy the hands determine the size of the perivascular zone, the diameters of the venous and arterial capillaries. The speed of propagation of the pulse wave and the value of endothelial function on the upper limb are determined synchronously with respect to the R peak of the electrocardiogram. Blood pressure is measured. The index K of the risk of cardiovascular complications is calculated using a mathematical formula. The device includes pneumatic means for creating an occlusion on the subject's limbs, pressure sensors associated with occlusal cuffs; an input unit capable of receiving, regulating the level of signals from the output of pressure sensors, amplifying and pre-filtering them; an optical capillaroscopy unit configured to determine the size of the perivascular zone, the diameters of the venous and arterial capillaries of the eponychium of the finger; an electrocardiogram recording unit, configured to generate a pulse synchronization signal along the R wave of the electrocardiogram; block of amplitude-digital conversion, digital signal processing and control, switching block, block of communication with a computer. The invention improves the reliability and objectivity of assessing the risk of cardiovascular complications.

The disadvantage is that the method and device only allow assessing the risk of CVD disease in the form of one general indicator, which does not give an idea to the specialist about the more specific state of the biomechanics of the cardiovascular system.

There is also known a method for diagnosing the state of the cardiovascular system (patent RU 2257838, IPC А61В 5/00, G06F 17/60, publ. 08/10/2005), according to which the selected conditions or signs are modeled, information parameters of the characteristic features of the state or feature of the model are compared with information parameters of the characteristic features of the initial state or sign of the patient, correct the definition of keywords, the creation of basic maps describing each of the possible states or signs in the space of all possible states or signs and the parameters of the model until the specified level of coincidence of the information parameters of the state and the sign of the model with the characteristic features of the initial condition or symptom of the patient and synthesize a realistic three-dimensional image of the resulting condition or feature of the model with characteristic features. During modeling, information parameters of the characteristic features of the selected state or feature are obtained by creating a model, the parameters of which and the patient's parameters are in certain unambiguous similarity relations. The method improves the quality and expands the functionality of diagnostics of the state of the cardiovascular system.

The disadvantage of this method is that it allows, to a greater extent, to visualize the state of the cardiovascular system based only on the ECG readings, which does not give a specialist a proper idea of the real state of the biomechanics of the cardiovascular system.

The closest analogue to the proposed invention is polycardiography (http: //bme.org/index.php/POLYCARDIOGRAPHY) - a combined study based on the simultaneous registration of several cardiovascular curves, more often ECG, phonocardiogram, carotid artery sphygmogram and - in subsequent versions - apexcardiogram. The method made it possible to determine the duration of the phases of the cardiac cycle. It should be noted that for the first time similar synchronous recordings for the purpose of phase analysis were made by Gerhartz back in 1911. In 1937, Schultz again used these curves, characterizing cardiac activity, and found the key to the original calculation with their help of the main systolic phases - the voltage period and the period exile.

The new principle was recognized by physiologists and clinicians only due to the colossal work that Blumberger did on the theoretical and practical substantiation of a new method for studying the phases of the cardiac cycle in humans (1940). The method was supplemented by V.L. Karpman and S. B. Feldman.

For phase analysis, other indirect methods are also used that record various manifestations of cardiovascular kinematics: rheography, phonocardiography.

Apexcardiography (ACG) is a method of recording low-frequency oscillations of the chest in the area of the apical point, caused by the work of the heart.

Sphygmography (SG) is a method of recording arterial wall movements that occur under the influence of a wave of blood pressure with each contraction of the heart. Oscillations of the vascular wall and the apical impulse area are sensed using a funnel connected to a pressure transducer. The output is carried out on paper or on the oscilloscope screen.

Rheography is a method of registering fluctuations in the resistance of body tissues to an alternating current of high frequency.

Phonocardiography (PCG) is a method of graphically recording sounds that occur during the work of the heart.

A polycardiogram in a typical case is a synchronous recording of ECG, PCG and SG of the central pulse. For ECG registration, I standard lead is used. PCG is recorded from the Botkin point in the mid-frequency range. FH is usually recorded from the carotid artery.

Currently, the method has lost its clinical significance for the following reasons: the need for simultaneous output of several curves on paper tape, the cumbersomeness of the equipment, manual processing of the results, assessment of only the duration of the phases of the cardiac cycle. The indicators obtained with this method are insufficient for an accurate assessment of the functional state of the cardiovascular system.

The present invention is directed to the identification of such a number of indicators that provide an accurate assessment of the biomechanics of the heart and blood vessels.

The technical result of the invention is to increase the rate of research of the biomechanics of the cardiovascular system, as well as to improve the quality of the examination.

The technical result of the invention is achieved by the fact that in the method for a comprehensive study of the biomechanics of the cardiovascular system, which consists in the synchronous recording of an apexcardiogram, sphygmogram, electrocardiogram and the subsequent determination of the duration of the phases of the cardiac cycle, simultaneously with other parameters, a rheogram is recorded, after which the results obtained by means of an analog a digital converter is transferred to a computer, where, in addition to determining the duration of the phases of the cardiac cycle, using the software, the duration of the phases of the vascular cycle is set, and the basic parameters of biomechanics are calculated in each phase of the cardiac and vascular cycle, then they are compared with the norm and differential diagnostics of major cardiovascular diseases.

The rheogram recording expands the range of indicators that provide an accurate assessment of the biomechanics of the heart and blood vessels.

Calculation of parameters using a computer and appropriate software makes it possible to carry out a differential diagnosis of major cardiovascular diseases, to give their prognosis in a particular patient, to carry out operational control over the dynamics of the state, including during treatment, which increases the speed of research on the biomechanics of the cardiovascular system, and also improves the quality of the examination.

The work of the method is characterized by the following figures:

in fig. 1 shows a general scheme of work of the method for a comprehensive study of the biomechanics of the cardiovascular system;

in fig. 2 shows the phases of the cardiac cycle according to ACT;

in fig. 3 shows the phases of the vascular cycle in the SG of the peripheral artery;

in fig. 4 shows the phases of the vascular cycle according to RVG;

in fig. 5 shows the cumulative distribution function;

in fig. 6 shows variants of the ratio of the integral distribution functions of two samples;

in fig. 7 shows the window of the program form for diagnosing the patient

The method is carried out as follows. The patient is placed on a couch, blood pressure (BP) is measured, patient data (name, age, etc.) and BP indicators are entered into the computer (1). A funnel is installed (with a cone over the investigated vessel with SG and over the area of the apical impulse with ACG) and the amplitude of the apexcardiogram and sphygmogram is recorded (automatically). In parallel, rheovasography (RVG) is recorded by applying electrodes to the limbs. The results are transmitted to a computer (1) by means of an analog-to-digital converter (ADC) (2) in real time. At the same time, an ECG is recorded in lead I.

Calculations of the main parameters of biomechanics in each phase of the cardiac and vascular cycle (duration, average and extreme speed, average and extreme acceleration, average and extreme power, work) are carried out according to a given program by a computer (1). Using the software package, the amplitude of the biomechanical curve is recorded, the resulting function is normalized, smoothed, and then its first and second derivatives are calculated. It turned out that the extremum points of the second derivatives of ACG, SG, RVG and their zero crossings correspond to the boundaries of the phases of the cardiac and vascular cycle. Knowing the first and second derivatives (speed V and acceleration A), determine the power N and work W in each phase, and for V, A and N, one can find both average (V _cp , A _cp , N _cp ) and extreme values ( V _ex , A _ex , N _ex ).

Here are the schemes for processing curves of ACG (Fig. 2), SG (Fig. 3) and RVG (Fig. 4) and determination of the phases of the cardiac and vascular cycles. The decoding of the ACG phases is presented in Table 1.

The decoding of the SG phases is presented in Table 2.

The decoding of the RVG phases is presented in Table 3.

A comprehensive analysis of all indicators of biomechanical curves allows for differential diagnosis of major cardiovascular diseases and control of their dynamics.

We have proposed the following technique. As the initial data, samples are taken containing the values of all biomechanical parameters for each analyzed group (healthy, patients with various forms of hypertension, coronary artery disease and CHF). In the MathLab environment, we present the differential and integral distribution laws for each pair of samples (for example, healthy - group 1 patients with coronary artery disease and CHF II functional class - group 2).

It is known that the cumulative distribution function is a function F (x) that determines for each possible value of x the probability that a random variable X will take a value less than x.

The geometric meaning of the cumulative distribution function is the probability that a random variable will take a value that lies to the left of the point x on the number axis (Fig. 5).

Theoretically, the following variants of the ratio of distributions of group 1 ("healthy", normal) and group 2 ("sick", pathology) are possible (Fig. 6).

Of all the parameters, those are selected for which the greatest differences of the compared groups are observed. Each group of patients with a specific diagnosis has its own minimum set of parameters for diagnosis.

In the Delphi environment, a program was created that allows you to load files with numerical characteristics of biomechanical curves of diagnosed groups, build histograms and an integral distribution law for them, find the percentage deviation of the value of each parameter in a diagnosed patient relative to the entire range of values in the sample. In the automatic mode, according to a specific algorithm, an analysis is carried out for the minimum set of parameters required for diagnostics for each sample. The program determines whether the patient is healthy and, if he is diagnosed as sick, the form of the disease is determined (Fig. 7). An additional analysis of the program's operation showed that the percentage of recognition accuracy is more than 90%.

Example. Patient M., 58 years old, examined using the claimed method for chronic heart failure, which developed against the background of hypertension and ischemic heart disease, before and after the course of treatment. The results of patient M. on ACG are presented in table 4.

The results of patient M. on the SG of the carotid artery are presented in table 5.

The results of patient M. on SG of the ulnar artery are presented in Table 6.

The results of patient M. on RVG ate are shown in Table 7.

As a result of a comprehensive analysis of the data obtained, the functional class of heart failure according to the New York classification (NYHA) was determined before treatment as III, after - II, which corresponded to the clinical data.

The method makes it possible to carry out differential diagnostics of the main cardiovascular diseases, to give their prognosis in a particular patient, to carry out operational control over the dynamics of the state, including during treatment. The method can be recommended for medical practice.

Claims (1)

A method for a comprehensive study of the biomechanics of the cardiovascular system, which consists in the synchronous recording of an apexcardiogram, sphygmogram, electrocardiogram and the subsequent determination of the duration of the phases of the cardiac cycle, characterized in that, simultaneously with other parameters, a rheogram is recorded, after which the results obtained are transferred to a computer where, in addition to determining the duration of the phases of the cardiac cycle, using software, the duration of the phases of the vascular cycle is set, and the basic parameters of biomechanics are calculated in each phase of the cardiac and vascular cycle, then they are compared with the norm and differential diagnostics of the main cardiovascular diseases.

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