The way to identify informative parameters of st-segment electrocardiograma and device for its implementation

 

The invention relates to medicine, namely to identify informative parameters of ST-segment electrocardiograma, namely the displacement, slope, shape, deviation of the peak ST-segment from its center, and combinations of these parameters, and can be used to analyze changes in ST-segment electrocardiogram (EX) to detect abnormalities in the early stages of heart disease. The method is characterized by the following sequence of actions. Carry out the discretization ST-segment shape on the time interval of existence of the ST-segment between the points start and end signals of the zero, first and second of the Walsh function. For each of these functions form the corresponding spectral coefficient. Compare the values of the spectral coefficients with a zero level and received the sign of the spectral factor judge proper informative parameter ST-segment. The device for implementing the method comprises a block forming electrocardiograma, block allocation of a QRS-complex, block allocation ST-segment block sampling, block the formation of the Walsh function, the set of spectral coefficients, a block to identify what provides increase the reliability of detection of the parameters of ST-segment and the ability to identify a greater variety of forms ST-segment. 2 AD. and 1 C.p. f-crystals, 11 ill.

The invention relates to medicine, in particular to electrocardiography, and can be used to analyze changes in ST-segment electrocardiogram (EX) to detect abnormalities in the early stages of heart disease.

Important from the diagnostic point of view are informative parameters EX, as an offset contour, slope, shape (convex or concave), apex offset in the case of convexity or concavity of the ST segment relative to its center, as well as various combinations of the listed parameters.

The most common in practical medicine way of identifying informative parameters of ST-segment [1], based on comparing recorded on a paper medium with EX special rules-patterns [1, 2]. When the deviation of the estimated parameter from the set of values is judged on the presence of certain diseases.

This method has a significant drawback. The most reliable informative parameters ST-segment are allocated only when the presence of the disease is obvious. This disadvantage is due to the low resolution of the above parameters, when these settings can accurately identify those at an earlier stage it is possible to diagnose the disease. This can be done using the automated measurement and analysis of parameters EX, including ST-segment. One such way is closest to the proposed (prototype) is a method of identifying informative parameters of ST-segment [3], namely, that electrocardiogram filter to eliminate interference from the mains 50 Hz, adjust the drift contours, eliminate from the analysis of atypical cardiocycle, average shape electrocardiograma on the interval specified duration, determined on the time axis, the position of the start points (H), mid () and end (To) ST-segment and measure the amplitude of u, Uc IR at specified points.

Known devices [4, 5], which allows to allocate the above-mentioned point on the EX and measure their amplitude. The use of three counts of ST-segment allows us to identify the offset, slope and nature of the shape (concave or convex). To do this, calculate the differencekN between IR and ulo and differenceSN=Uc-ulo,cs=IR Uc. Identification of informative parameters of ST-segment U, Uc IR are below the zero line, that is ST segment depression, and when above the elevation of the ST segment.

The tilt parameters:

ifSN=the COP andkN>0, the depression or elevation Kosovskaya, and ifkN<0, then colonista.

Shape options:

ifSN>KS, form ST-segment convex, and ifSN<the COP, then concave.

This method has drawbacks consisting in low noise and the inability to detect the displacement of the top of the ST-segment relative to its center. Low immunity due to the following circumstances:

1) since the identification of informative parameters of ST-segment is based on the values of samples taken at specific points (N, S, K), then the effect of interference (noise amplifier drift, pulse interference from external sources) these values can be distorted, which will contribute to the error in the estimation of parameters;

2) using the difference of the first orderkNshall be known way to action interference;

3) averaging cardiomegaly on the interval specified duration, which is the one known method, minimizes the effect of noise, but in the early stages of the disease, the effect of the displacement of the ST segment may appear a short time (a few cardiocycle), and increase the duration of the averaging interval required for larger mitigate noise, may lead to the decrease of the values of u, Uc, IC, and hence distortion of the estimation of the parameters of ST-segment.

The proposed method allows to eliminate the mentioned disadvantages and to provide a reliable identification of informative parameters of ST-segment.

The authors found a relationship between the parameters of the ST segment and the values of the spectral coefficients Ck, the combination of which may be represented by the signal ST-segment basis functions Walsh [6]. For a discrete signal ST-segment process of formation of spectral coefficients can be described by the expression

where Uithe amplitude of the i-th discrete reference signal ST segment, i=1, 2, ..., N;

N is the number of discrete samples of the signal ST-segment;

Walik- the value of the k-th Walsh function at a time, Sedogo spectral coefficient includes all discrete samples ST-segment. Thus, each coefficient is an integral estimate of the corresponding parameter ST-segment, unlike the point estimates in the known method (prototype) obtained according to the values of samples taken at specific points (H, C, K). Thanks for the calculated coefficients Ckincreasing the ratio of signal to noise in comparison with samples taken at specific points (N, S, K), which allows more reliable detection of informative parameters ST-segment even within a single cardiac cycle, without resorting to averaging many cardiocycle.

In Fig.1 shows the first three Walsh functions.

Fig.2, ..., Fig.7 illustrate the relationship of spectral coefficients with the informative parameters of the ST-segment.

The existence of informative parameter is determined by the sign of the corresponding spectral coefficient.

Factor0represents the sum of all samples ST-segment during its existence. A positive value With0indicates the dominant displacement of the ST segment above the contour, that is, elevation of the ST segment (Fig.2,a), a negative value of dominant offset below the contour, that is, depression of the ST segment (Fig.2,b). In the case of distortion of the ST-segment is based, clearly predominant in the spectrum (Fig.3,a and 3,b). The higher the value of the module With0, the stronger is the displacement of the ST segment above or below the contour.

The difference from zero of the coefficient C1determines the decrease or increase of the signal at the interval of its existence (Fig 4,a and 4,b). When C1>0 (Fig.5,a) ST-segment has a predominantly top-down nature, and when C1<0 (Fig.5,b) upward. The larger the module C1, the more pronounced slope. In the case of C1=0 ST-segment horizontal.

Factor2determines the shape of the ST segment, i.e. the presence of convexity or concavity. When the convex shape of the ST segment (Fig.6,a)2<0 (Fig.7,a), and when the concave (Fig.6,b) - C2>0 (Fig.7,b). With increasing modulus ratio2the degree of convexity or concavity increases. In the absence of concavity or convexity With2=0 (Fig.4, 5).

The difference from zero of a few spectral coefficients indicates the combination of ST-segment. Simultaneous contrast of zero spectral coefficients C1and C2(Fig.7,and Fig.7,b) shows the displacement of the vertices of the convex or concave ST-segment relative to its middle (Fig.6,and Fig.6,b), and at the same C is shifted to the right from its center (Fig.6,b), and with different signs - to the left of center (Fig.6,a).

Thus, to identify the above informative features of the ST-segment is sufficient to identify the difference between zero and the signs of the three spectral coefficients: C0C1and C2.

The essence of the proposed method consists in the following. Electrocardiogram filter to eliminate interference from the mains 50 Hz, adjust the drift contours, eliminate from the analysis of atypical cardiocycle determine on the time axis positions of the points of the beginning and end of the ST-segment. Then proposed the following sequence of actions. Carry out the discretization ST-segment shape on the time interval of existence of the ST-segment between the points start and end signals of the zero, first and second Walsh functions, for each of these functions form the corresponding spectral coefficient, C0C1or2. Values of the spectral coefficients is compared with a zero level and received the sign of the spectral factor judge proper informative parameter ST-segment.

The formation of the corresponding spectral coefficient can be done by adding all the discrete samples of the ST-segment is on the “Plus” sign and when the Walsh code is equal to “-1”, the count of ST-segment invert and add in the amount with a Minus sign [6].

Identification of informative parameters of ST-segment can be carried out as follows:

when positive With0ST-segment offset higher contours (elevation ST-segment), negative With0ST-segment offset lower contours (depressed ST segment);

when positive C1ST-segment has conisholme slope, negative C1- coowachobee;

when positive With2form ST-segment concave, negative With2- convex;

with the same characters C1and C2(both C1and C2positive or negative) peak ST-segment shifted to the right from its center, and with different signs - to the left of center;

other combinations of characters spectral coefficients With0C1and C2determine other possible combinations of informative parameters, characterizing the change in the ST segment.

The proposed method allows a fair comparison with the known method (prototype), to identify informative parameters ST-segment even within a single cardiac cycle, which contributes to earlier obnarujenia is illustrated in the following graphics:

- Fig.8 is a structural diagram of a device that implements the proposed method;

- Fig.9 is an embodiment of the block of formation of spectral coefficients;

- Fig.10 is a timing chart explaining the operation of the processing unit of spectral coefficients;

- Fig.11 - implementation option unit detection informative parameters of ST-segment.

To achieve the technical result consists in increasing the reliability of detection of informative parameters of ST-segment and make it possible to identify a greater variety of forms ST-segment, and the implementation of the proposed method in the device containing the block forming electrocardiograma, block allocation of a QRS-complex, block allocation ST-segment display unit, and the output processing unit EX is connected to the input unit of allocation of a QRS-complex and to the first input unit selection ST segment, a second input connected to the output of the block selection QRS-complex, the entered block sampling, block the formation of the Walsh function, the set of spectral coefficients, the block detection of informative parameters of ST-segment, and the input unit of sampling is connected to the first output unit selection ST segment, the second output unit selected input block the formation of spectral coefficients, forming a first group of inputs of this block, to the inputs of the second group which is connected to the corresponding outputs of the processing unit of the Walsh function, the outputs of the block of formation of spectral coefficients connected to respective inputs of block identification of informative parameters of ST-segment whose outputs are connected to respective inputs of the indication unit.

The unit consists (Fig.8) from the block forming electrocardiograma 1, unit selection QRS-complex 2, unit selection ST-segment 3, unit 4 sampling, processing unit 5 of the Walsh function, the processing unit 6 of spectral coefficients, unit 7 identify informative parameters of ST-segment electrocardiograma and the display unit 8.

The output processing unit EX 1 connected to the first input unit selection ST-segment 3 and to the input of block allocation of a QRS-complex 2, the output of which is connected with the second input unit selection ST-segment 3. The first output (information) unit selection ST-segment 3 is connected to the input of the sample 4. The second output (control) unit selection ST-segment 3 is connected to the input of the processing unit 5 of the Walsh function. The processing unit 6 of the spectral coefficients has two groups of inputs: the first group is PI are the control inputs connected to respective outputs of the processing unit 5 of the Walsh function, the number of inputs of the second group is equal to the number of generated spectral coefficients. The outputs of the shaping unit 6 spectral coefficients are connected to the corresponding inputs of the detection unit 7 informative parameters electrocardiogram, and the outputs of the latter are connected to the corresponding inputs of the indication unit.

The set of Walsh functions can be performed based on the flowchart shown in [6] in Fig.7-11.

An embodiment of the block of calculation of spectral coefficients With0C1and C2shown in Fig.9. It consists of blocks of multiplication 9 discrete samples ST-segment electrocardiograma the corresponding Walsh code from a number of these functions and the adders 10 received works, and to calculate the spectral ratio With0not required block multiplication, and one adder 10. In turn, the unit 9 multiplication is performed on the basis of the differential amplifier consisting of an operational amplifier 11 and the first 12, 13 second, third 14 and 15 fourth resistors, and the key diagram, which consists of the first 16 and second 17 keys and inverter 18. In each block multiplication 9 the first output of the first resistor 12 and an information input of the first key 16 soedinevol one of the adders are connected, and the point of their connection is an information input processing unit 6 spectral coefficients, i.e., the first input connected to the output of block sampling 4. The second terminal of the first resistor 12 is connected with the first output of the fourth resistor 15, and the point of their connection is connected to the inverting input of the operational amplifier 11. The output of the operational amplifier is connected with the second output of the fourth resistor 15 and an output unit 9 multiplication. The output of the key 16 is connected to the first output of the second resistor 13, the second terminal of which is connected to the first output of the third resistor 14, and the point of its connection connected to the not inverting input of the operational amplifier 11. The second terminal of the third resistor 14 is connected to the output of the second key 17, the information whose input is connected to GND. The control input of the first key 16 is connected to the input of the inverter forming the control input unit 9 multiplication, the control inputs of all units of multiplication 9 form a second group of inputs of the processing unit 6 of spectral coefficients, each of the inputs of this group is connected to the output of the processing unit 5 of the Walsh function. The output of the inverter 18 is connected with the control input of the second key 17. The output 6 of the spectral coefficients. The spectral coefficients can be represented in the form of analog signals or digital signals, for example in the form of binary code.

Embodiment of the detection unit 7 informative parameters of ST-segment for the case when the spectral coefficients are presented in the form of binary code shown in Fig.11. It consists of digital Comparators 19, 20, 21 signals and logic circuits 22, 23 (in the example, this scheme 3). The group of inputs And each of the Comparators 19, 20, 21 connected to the corresponding outputs of the processing unit 6 of the spectral coefficients. The group of inputs of all Comparators 19, 20, 21 connected to the common wire. The outputs of the Comparators 19, 20, 21 are connected to corresponding inputs of the logic circuits 22, 23. The signal (1 or 0) at the output of each logic circuit determines the presence or absence of the signal ST-segment corresponding informative sign.

The device operates as follows. The block forming electrocardiograma performs the usual operations: enhance electrocardiogram, frees him from interference frequency filtering and eliminates drift contours using a high pass filter or by separating the signal drift indesigne [3]. Purified from interference EX arrives at the inputs of the block allocation of a QRS-complex 2 and unit selection ST-segment 3. In the block selection QRS-complex is formed, the signal of the beginning of the next cardiac cycle (starting point), supplied to the second input (control input) unit selection ST-segment. Based on the known structure of the FORMER and a reference point in the block 3 are formed the starting point and the end of the ST-segment. Isolated from EX ST-segment enters the block sampling 4 where it is converted into a sequence of discrete samples U; (Fig.10). Graph of Fig.10,can be taken as illustrations of the work sample 4, since the Walsh code number zero identically equal to 1. For definiteness, it is accepted that ST-segment has coowachobee character. The signal on the control output unit selection ST-segment 3 initializes the operation of the processing unit 5 of the Walsh function, the respective outputs of which are formed of these features. It was noted above that for the detection of informative parameters of ST-segment sufficient to identify the difference from zero of the three spectral coefficients: C0C1and C2. You can use the following functions Walsh: null Wal0(Fig.1,a), the first Wal1(Fig.1,b) and the second Wal1. Signal functions Wal1with the corresponding output of the processing unit 5 of the Walsh function is supplied to the control input of the corresponding unit 9 multiplication, namely, the control input key 16 and through an inverter 18 to the control input of the key 17. In the first half of the existence of a signal Wal1when it is equal to 1 (Fig.10,and the key 16 is closed, and the switch 17 is open. Thus the gain of the differential amplifier consisting of an operational amplifier 11 and resistors 12, 13, 14 and 15, by not inverting input is equal to +2, and by inverting -1. The total gain is equal to +1. Thus, the counts of the ST-segment is repeated at the output of the amplifier (Fig.10,g), which is equivalent to multiplication by +1. In the second half of the existence of a signal Wal1(Fig.10,and the key 16 is opened, and the switch 17 is closed. The differential amplifier operates as an inverter of the input signal. Samples of ST-segment inverted (Fig.10,g), which is equivalent to multiplying by -1. Thus, the output unit 9 multiplication signals are formed works U1*Walil

Because Wal0equal to 1 in the whole range of its existence, the works Ui*Wali0you can use directly the output signal of the block sampling (Fig.10,in).

The output signal of the unit 9 multiplication is fed to the input of the corresponding adder 10. Each of the adders 10, included in the processing unit 6 of spectral coefficients, sums of sequences of works samples ST-segment and of the Walsh function. At the output of adders signals are formed corresponding spectral coefficients. The summation operation can be implemented as analog signals, and digital. In the first case, each spectral coefficient is represented by a voltage of an appropriate level and mark the second binary code. To receive digital signals works Ui*Walikat the input of the adder enough to use analog-to-digital Converter (ADC).

From the outputs of the shaping unit 6 spectral coefficients of the signals of the latter are received at the respective inputs of the detection unit 7 informative parameters of ST-segment. A possible implementation of the detection unit 7 informative parameters ST-segagaga spectral coefficient Ckcomes on a group of inputs And the corresponding digital comparator 19, 20, 21 (made, for example, on the chip type 564 IP2). A group of inputs connected to the common wire, i.e., the signals on these inputs are zero. Depending on the value and sign of the spectral coefficient to one of the three outputs of the comparator 19, 20, 21, there will be a signal of logical 1, and the remaining two outputs of the signal is a logical 0. The signals from the outputs of the Comparators 19, 20, 21 are received at the respective inputs of the logic circuits of the type And (Fig.11 is a schematic 22 and 23). The outputs of the logic circuits, which are the outputs of the detection unit 7 informative parameters of ST-segment signals are formed, meet informative parameters of the ST-segment. These signals are characterized by the presence of the option, his character, and, if so, the combination of parameters. The presence of the corresponding parameter or combination of parameters causes a logical 1 to the respective output of the detection unit 7 informative parameters of ST-segment. In Fig.11 shows some of the possible combinations of the ST-segment.

The signals detected informative parameters of ST-segment arrives at the inputs of the indication unit, which can be>redlounge device allows you to more reliably in comparison with the known devices to identify informative parameters ST-segment and identify a greater variety of forms ST-segment that contributes to the detection of abnormalities in the early stages of heart disease.

Literature

1. Reference electrocardiography / Ed. by B. N. Medvedev. St. Petersburg, Peter. 2000.

2. RF patent 2026636, class. And 61 In 5/02.

3. The heart monitor. Equipment for continuous monitoring of ECG/A. L. Baranovski, A. N. Kalinichenko, L. A. Attracted etc.: edited by A. L. Baranovsky and A. P. Nemirko. M.: Radio and communication. 1993.

4. RF patent 2026637, class. And 61 In 5/04.

5. RF patent 2134060, class. And 61 In 5/04.

6. Manovtsev A. P. fundamentals of theory of radio telemetry. M: Energy, 1973.

Claims

1. The way to identify informative parameters of ST-segment electrocardiograma, namely, that electrocardiogram filter, adjust the drift contours, eliminate from the analysis of atypical cardiocycle determine on the time axis, the position of the beginning and end of the ST-segment, determine the informative parameters of ST-segment, and then analyzed, characterized in that when determining the informative parameters shall increment Ignacy zero, the first and second Walsh functions from discrete samples of the signal ST-segment for each of these functions form the corresponding spectral coefficients whose values are compared with a zero level, and when the contrast obtained by the sign of the spectral factor judge proper informative parameter ST-segment.

2. The device for implementing the method of identifying informative parameters of ST-segment electrocardiograma containing block forming electrocardiograma, block allocation of a QRS-complex, block allocation ST-segment display unit, and the output processing unit EX is connected to the input unit of allocation of a QRS-complex and to the first input unit selection ST segment, a second input connected to the output of the block selection QRS-complex, characterized in that it additionally introduced block sampling, block the formation of the Walsh function, the set of spectral coefficients, the block detection of informative parameters of ST-segment moreover, the input unit sampling is connected to the first output unit selection ST segment, the second output unit selection ST-segment is connected to the input of the processing unit of the Walsh function, the output of block diskretizacijos block, to the inputs of the second group which is connected to the corresponding outputs of the processing unit of the Walsh function, the outputs of the block of formation of spectral coefficients connected to respective inputs of block identification of informative parameters of ST-segment whose outputs are connected to respective inputs of the indication unit.

3. The device according to p. 2, characterized in that the set of spectral coefficients contains N-1 (N=2, 3,...) blocks the multiplication of discrete samples ST-segment electrocardiograma the corresponding Walsh code from a number of these functions and N adders, the first (information) inputs of all units of the multiplication and the input of the first adder are connected, forming a first group of inputs of the block of formation of spectral coefficients, the output of each block multiplication is connected to the input of one of the other N-1 adders, the outputs of the adders are the outputs of the block of formation of spectral coefficients, moreover, the block multiplication is performed on the basis of the differential amplifier consisting of an operational amplifier and the first, second, third and fourth resistors, and the key circuit consisting of first and second keys and the inverter, in each block of multiplying the first output of the first Rezia, the second terminal of the first resistor is connected to the first output of the fourth resistor and the inverting input of the operational amplifier, the output of which is connected with the second output of the fourth resistor, and an output block multiplication, the output of the first key is connected to the first output of the second resistor, the second terminal of which is connected to the first output of the third resistor and reinvestiruet the input of the operational amplifier, the second terminal of the third resistor is connected to the output of the second key information the input of which is connected to the shared bus, the control input of the first key is connected to the input of the inverter forming the control input of block multiplication, the control inputs of all units multiplication form a second group of inputs of the block of formation of spectral coefficients, the output of the inverter is connected with the control input of the second key.



 

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SUBSTANCE: method involves carrying out pulsating Doppler echocardiographic examination. Mean pressure is determined in pulmonary artery. Mean pressure in pulmonary artery being less than 13 mm of mercury column, no cardiac rhythm disorders risk is considered to take place. The value being greater than 13 mm of mercury column, complex cardiac rhythm disorder occurrence risk is considered to be the case.

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