RU2687566C1 - Method for determining a functional condition of a person by a phonocardiogram - Google Patents

Abstract

FIELD: medicine.SUBSTANCE: invention relates to medicine. Method for determining a functional state (FS) of a person by a phonocardiogram (PCG) involves forming a dynamic series of cardiointervals, calculation of voltage index (VI) of regulatory systems, determination of FS depending on value of VI. PCG is recorded on the apex of the heart, the I tone is recognized on the initial PHG fragment with duration of 2–3 s by way of threshold signal filtration with subsequent measurement of pauses duration between three consecutive amplitudes. Number of count, which is preceded by the maximum pause, is recorded as the start of the first tone and the count corresponding to its end is determined. Scanning interval corresponding to I tone duration, and the reading with the maximum amplitude is recorded as the first (initial) reading of the I tone on the PCG, and subsequent readings of the I tones by the maximum amplitude at the intervals [n1 n2] are determined. Duration of cardio intervals is calculated between I tones of PCG and intra-cycle parameters of cardiac activity are additionally determined: systole, diastole and ratio of amplitudes of I and II tones. Counts of the II tones are determined from the maximum amplitude on the intervals [n3 n4]. Systole values are determined by the number of readings between the I and II tone, the diastole by subtracting the systole from the duration of the cardio interval and the values of the dynamic rows of intra-cycle parameters (systole and diastole) by variational pulsometry. It is compared with standard values and, in cases of exceeding them in premorbid state, observing the presence of a pathological process.EFFECT: higher sensitivity of PS assessment and early detection of the beginning of the pathological process by determining phases of the cardiac cycle and ratios of I and II tones.1 cl, 3 dwg

Description

The invention relates to medicine, namely to the diagnosis of the functional state (FS) of a person according to the results of measurement of parameters of the cardiovascular system (SSS) and can be used in individual individualized health monitoring.

To determine the FS involved the following methods for studying the functioning of the cardiovascular system:

- study of the time sequence of the RR intervals of the electrocardiogram (ECG) in one lead [1, 2, 3];

- study of the functioning of the heart by determining systolodiastolic ratios [4];

- study of the dynamics of amplitude ratios of I and II tones [5, 6].

There is a method of assessing the FS of the human body (RF patent No. 2083155, published. 07.07.1997), including the registration of RR-intervals and the subsequent calculation of the entropy of the duration of RR-intervals (E) by the formula:

where mi is the number of RR-intervals of a given duration in a sample of 100;

mi / 100 is the probability of RR-intervals of a given duration in a sample of 100;

and with a value of 50 <E <70, the person's FS is assessed as stable.

The disadvantage of this method is its limited information content. The concept of “sustainable FS”, as one single state, is not considered in the methodical materials recommended for practical use.

There is a method of determining the functional state of a person (RF patent №2289301, publication of a patent of 20.12.2006), according to which heart rhythm activity is recorded, the duration of cardiointervals is measured, the indicators used in variational pulsometry are used to assess the degree of tension of regulatory systems: mode intervals, mode amplitude, variational scope. At the same time, systolic and diastolic blood pressure values are measured simultaneously with the registration of the cardiac rhythm. The value of the FS index is calculated taking into account the specified parameters, according to the appropriate formula, and compared with the standard values.

The disadvantage of this method is the need to attract additional equipment. The process of automating the process of self-assessment of the FS is becoming more complex, especially for people with disabilities.

The “Method of assessing the rhythmmochroon-inotropic activity of the heart in a person of a mature and elderly age” is known (Patent No. 2123278 published 12/20/1998). which is carried out by registering the heart rate, duration of the cardiac cycle, total diastole, general, electrical and mechanical systole, periods of expulsion and voltage with the phase of asynchronous and isometric contraction using classical polycardiography, cardiac output and cardiac index using integral body rheography, systemic average arterial oscillography, and the differential diagnosis of cardiac performance, ayuschiysya in that the differential diagnosis of the heart is carried out with the allocation of organization features typological hronokardiologicheskoy functional system and clarify quantitative optimum rhythm, chronotropic and inotropic function of the heart at different values of systemic blood pressure and blood flow.

The main disadvantage of this method is the difficulty in its implementation. It is not designed for individual use by an “ordinary” person.

The analysis of the functioning of the cardiovascular system, recognized by the prenosological method of studying the functioning of the cardiovascular system, is recognized both in Russia and abroad. The HRV method is recommended for determining the body's FS and individual health control [1, 3].

The study of the signal of HRV is a temporary sequence of RR intervals of the electrocardiogram (ECG), recorded according to the scheme of one lead. As a criterion for assessing the status of the CCC, the tension index of regulatory systems (IN) is used, calculated by the formula:

IN = AMO / 2 * Mo * BP,

where Mo is (fashion) the most common value of the duration of cardiointervals. AMO - (mode amplitude), the number of cardiointervals in%, corresponding to the range of fashion. BP - (variational range), the difference between the maximum and minimum value of the cardiointerval.

The FS of the body is determined by the value of the IN: the lower the degree of tension of the regulatory systems, the lower the price the body pays for its adaptation to various influences. Specifically, a person's FS is determined by comparing the IN with the standard values.

The prototype of the FS evaluation method is used as a prototype. It consists in recording ECG, recognizing R-waves, measuring the duration of RR cardiointervals, forming dynamic series of cardiointervals, calculating the stress index of regulatory systems (IN) and determining the human FS from the results of comparison of IN with standard values . ("Heart rate variability", 03/31/2014, http://edu-biz.org/2014/03/31/variabelnost-serdechnogo-ritma/).

The main disadvantage of the method described above is the low sensitivity of early diagnosis of pathological conditions of the body, due to the fact that the analysis is based on the study of only one parameter CCC - the duration of cardiocycles.

It is known that the formation of the end result of the activity of the heart, as a pump, occurs under the influence of a number of factors, the most important of which are the intervals between contractions. The functional state of the cardiovascular system is influenced by systolodiastolic intracyclic ratios [4].

Known auscultatory pathology of tones: weakening and strengthening, accentuation [5]. Normally, over the apex of the heart, the amplitude of the first tone is greater than the second. In the event that the amplitude of the first tone is equal to the second or less, this indicates a weakening of the first tone, one of the reasons for which is the insufficiency of the mitral valve [6].

The purpose of the invention is to increase the sensitivity of FS evaluation, expressed in the earlier detection of the onset of the pathological process due to the additional determination in each cardiointerval of the duration of systole, diastole and the ratio of amplitudes of the first and second tone.

This goal is achieved through the use of phonocardiogram (PCG) as a cardiographic recording and method of its research.

It should be noted that at present, electronic stethoscopes (ES) are widely used, making it possible to use digitized sound to implement automated algorithms for detecting abnormalities in the work of the heart. Obvious constructive advantages of ES, compared with cardiac monitors, and greater clinical information content of PCG compared to single-lead ECG, makes the method of assessing the FS of the body for PCG registration preferable.

"Normal" PCG consists of oscillations of I, II, and often III, IV heart sounds. Between I and II tone is systolic, and between II and I - diastolic pause. The cardiac cycle is systole and diastole of the heart, periodically repeated in strict sequence. From which it follows that the cardiointerval on PCG is determined by segment I-I.

The optimal listening point I tone is located at the apex of the heart, where I tone is louder than II. But at the same time, when choosing the sign of determining the beginning of I tone, it was taken into account that the “normative ratio” of amplitudes of tones can be leveled, given that the location of the optimal listening point of I tone on a human body is somewhat random, since everyone’s heart is different . A certain influence on the measurement error can have a tremor of the hand holding ES, and noises of various nature.

The nature of the alternation of pauses duration is taken as the most effective sign of I tone identification: I tone follows a long pause, and II follows a short pause (diastole is greater than systole). The reliability of the feature is automatically provided by the rules of procedure for HRV:

- operational research should be conducted in conditions of relative rest in the “lying” or “sitting” position;

- when processing a record, the concept of NN-intervals (normal-to-normal) is used, that is, the intervals only between normal abbreviations are taken into account; intervals recorded during heartbeat disturbances, as well as those resulting from external interference, are excluded from the analysis;

- cardiointervalogram is considered as a stationary random process.

The nature of the alternation of pauses is broken when the heart rate (HR) is above 130 beats / min. - diastole becomes less systole. The upper limit of the norm is considered to be 90 beats / min. Since the HRV values that indicate a violation of the “norm” of the heart rhythm, the use of HRV is excluded, then the conditions are eliminated under which the accepted sign of recognition is not observed.

About HRV is traditionally judged by the duration of the RR-intervals, although more correct, it is considered considering the duration of the PP-intervals. Estimation of RR-intervals is associated with the fact that it is almost impossible to localize the point of beginning of the P wave on the ECG recorded on modern devices [2]. The R-wave is the largest in amplitude and is most easily distinguished by computer processing.

Similar is the case in PCG. The beginning of the I tone cannot take the data obtained by measuring the very first, initial vibrations of the I tone, since these vibrations have a very small amplitude. Therefore, the measurement of the duration of systole from the first high vibration of the I tone to the first high vibration of the II tone is the most objective. (The temporal ratio of mechanical and electrical systole of the heart in healthy children. Http://anginastop.ru/elektrokardiografiya/tekhnika-i-metodika-fonokardiografii./)

The central part of the I tone consists of 3-5 large amplitude oscillations. In this case, usually one of the teeth of the central part has the maximum amplitude, according to which the judgment about the amplitude (intensity) of the I tone is formed.

The basis of the I tone identification is based on the consideration that to determine which of the pauses is systole and which is diastole, it is necessary to have at least three dimensions of the pauses between the amplitudes of the tones. Since the duration of the cardiac cycle is of the order of 1 s, the determination of which of the pauses is systole and which of diastole can be set on a 2-second FCG recording. Considering that the cardiointervalogram is considered as a stationary random process, the subsequent determination of I-tone samples can be performed on the original PCG record, without filtering, at intervals calculated using the data obtained at the 2-second interval.

Recognition of the I tone is carried out by extracting from the FKG recording a fragment of at least 2 s, on which the threshold filtering of the signal is performed (threshold value (0.5-0.7) from the maximum amplitude), the duration of the pauses between three consecutive amplitudes is measured. The number of the reference, which is preceded by the maximum pause, is taken as the beginning of the I tone and the counting corresponding to its end is determined (the duration of the I tone ~ 0.14 s). The interval corresponding to the duration of the I tone is scanned and the count with the maximum amplitude is fixed as the first (initial) count of the I tone on the PCG. The samples of the subsequent I-tones are determined by scanning at intervals [n1 n2] calculated by the formulas:

n1 = N + 0.9 * Tin0 * Fs; n2 = N + 1.1 * Tin0 * Fs,

(N is the count of the previous I tone, Tin0 is the duration of the cardiointerval measured on a fragment of the filtered signal, Fs is the measurement frequency).

Calculate the duration of cardiointervals between the I tones of PCG and additionally determine the intra-cycle parameters of cardiac activity: systole, diastole and the ratio of the amplitudes of the I and II tones.

Counts II tones determined by the maximum amplitude at intervals [n3 n4], calculated by the formulas:

n3 = N + 0.3 * t0sist * Fs; n4 = n3 + 0.8 * t0sist * Fs.

(t0sist - systole duration, measured on a fragment of the filtered signal).

On each cardiointerval, the duration of systole is determined by the number of counts between I and II, and the duration of diastole is determined by subtracting the systole value from the duration of the cardio interval.

It should be noted that the result of HRV is an assessment of the state of the body: "normal", "premorbid state", "pathology". The problem of establishing individual FS ranges, as applied to the FS assessment, is currently not resolved and requires further in-depth development ”[1]. In practice, use of statistical standard values IN. These circumstances make it practically impossible to detect the onset of pathological progress using the method taken as a prototype.

In this connection, the fact described in the article by V.A. Zagryadsky, A.L. Rozanov, V.P. Malignant. “Twenty years of cosmic electropuncture (p. 8)”: “It should be noted that if FS at the level of the whole organism can be identified between“ normal adaptation ”and“ functional deviation ”, then individual systems of the organism were in a worse position during certain periods of space flight. between "pronounced deviations" and "pathology" requiring correction. "

From this fact, it follows that the pathological process and the pathological state are of local importance if there is no reaction of the whole organism to the pathogenic factor. For example, if systolodiastolic intracyclic ratios exceed the norm, and the body's FS is in a “premorbid state”, then this indicates compensation by the body of the resulting dysfunction.

Weak changes detected repeatedly and progressively increasing, should be regarded as signs of emerging pathological changes that can lead to disease.

Taking into account changes in the components of the cardiac cycle can identify changes in one or more of them and thereby diagnose changes in the functional state of the heart as a whole.

The possibility of establishing the fact of arising dysfunction, which potentially could lead to a deterioration of the current FS, is proof of the increased sensitivity of the FS evaluation carried out by the claimed method.

In prenosological diagnosis, the concept of pathology is interpreted as an imbalance. Therefore, the methodology used to assess the FS of the organism as a whole can also be used to assess the FS of its individual subsystems. The adequacy of this diagnostic approach has been proven clinically and in model experiments [7, p. eleven]. Therefore, it is advisable to determine the indicators of the dynamic series of the cyclic phase phases of cardiac activity using the same method of variation pulsometry, which was used to assess the degree of tension of the HRV regulatory systems.

The technical result consists in increasing the sensitivity of the evaluation of FS, namely, in earlier detection of the onset of the pathological process by determining the phases of the cardiac cycle and the ratios of the amplitudes of the I and II tones.

An important advantage of the proposed method is its feasibility in the application to the smartphone. Electronic stethoscope with Bluetooth system is attached to the human body in the apex of the heart. Heart sounds are recorded on the smartphone's voice recorder and are processed using the smartphone's processor.

The method can be used in individual-prenosological health control. The implementation of an individual system, can be used for remote preventive examination of large populations of the population, with the aim of early detection of pathological conditions of the cardiovascular system.

The possibility of implementing the method is illustrated by the following figures:

FIG. 1 Original PCG record (16 s) at the apex of the heart, discreteness 1000 Hz. The recording was made with the help of an experimental prototype of an ES microphone of which is embedded in the head of the ST-72 stethoscope of the Microlife company.

FIG. 2 The initial 3-second fragment of the original PCG recording.

FIG. 3 - FKG fragment after threshold filtration

Numbers of counts of the first three amplitudes [3019 6455 11719]. The time between three counts (s) [0.30 0.34 0.53].

The maximum pause duration is 0.53 s, preceding the third amplitude. According to the recognition sign of the I tone, the count corresponding to this amplitude is taken as the beginning of the I tone. The diastole value is 0.53 s, the systole value (t0sist) is 0.34 s. The duration of the cardiac interval (Tin0) is 0.87 s. The value of the third count of the third amplitude N = 11719 is taken as the first count of the subsequent I-tones.

Information sources.

1 Baevsky P.M. Analysis of heart rate variability using various electrocardiographic systems (methodical recommendations) / P.M. Baevsky, G.G. Ivanov, L.V. Chireykin et al. // Bulletin of arrhythmology. - 2001. - №24. - p. 65-87.

2 "Heart Rate Variability". Standard of measurement, physiological interpretation and clinical use. Working Group of the European Society of Cardiology and the North American Society of Stimulation and Electrophysiology. www.hrv.ru

3 Isaeva O.N. Physiological rationale for telemedicine prenosological individual control systems: dis. Cand. biologist. Sciences: 14.03.08. // Isaeva Olga Nikolaevna. - M., 2015. - 203 p.

4 Karpman V.L. Phase analysis of cardiac activity. M .: Medicine, 1965, 275 p.

5 Auscultation of the heart: listening points, algorithm and interpretation. https://moyakrov.info/heart/auskultatsiya-serdtsa

6 Phonocardiography - Sound symptoms of acquired heart defects, http://lekmed.ru/info/arhivy/zvukovaya-simptomatika-priobretennyh-porokov-serdca-13.html.

7 Zagryadsky V.A. The device electropuncture assessment and correction of the functional state of the body "Prognosis - Mini". Instructions for use. Version 1.0, 1992 - 34 p.

Claims (5)

The method of determining the functional state (FS) of a person by phonocardiogram (PCG), including the formation of a dynamic range of cardiointervals, the calculation of the stress index (IN) of regulatory systems, the determination of FS depending on the size of the IN, characterized by the fact that PCG is recorded at the apex of the heart, I recognize tone on the initial fragment of the FKG with a duration of 2-3 s by the threshold filtering of the signal followed by measuring the duration of the pauses between three consecutive amplitudes, with the reference number being the orom is preceded by the maximum pause, fixed at the beginning of the I tone and the counting corresponding to its end is determined, then the interval corresponding to the duration of the I tone is scanned, and the count with the maximum amplitude is fixed as the first (initial) count of the I tone at FCG and the subsequent readings of the I tone are determined maximum amplitude at intervals [n1 n2], calculated by the formulas n1 = N + 0.9 * Tin0 * Fs, n2 = N + 1.1 * Tin0 * Fs (N is the countdown of the previous I tone, Tin0 is the duration of the cardiointerval measured on the filtered signal fragment, Fs is the measurement frequency), then calculate the duration of cardiointervals between the I of PCG tones and additionally determine the intra-cycle parameters of cardiac activity: systole, diastole and amplitude ratio of I and II tones , while the samples of the II tones are determined by the maximum amplitude in the intervals [n3 n4] calculated by the formulas n3 = N + 0.3 * t0sist * Fs; n4 = n3 + 0.8 * t0sist * Fs (t0sist - systole duration, measured on a fragment of the filtered signal), then determine the systole values by the number of counts between I and II tone, diastoles by subtracting the systole values from the cardio interval, and the indicators of the time series of intra-cycle parameters (systoles and diastoles) by variational pulsometry compared with standard values, and, in cases of their excess in the premorbid state, they record the presence of the pathological process that has arisen.

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