CN101933803B - Cardiac mapping signal analyzing and processing device and method - Google Patents

Abstract

The present invention proposes a cardiac mapping signal analysis and processing device and method, in particular a device and method for analyzing the rhythm state of the cardiac mapping signal. The device of the invention includes: a mapping electrode, a multi-stage amplifier, a data acquisition card, an acquisition module, a signal analysis and processing unit and an output device. The method of the present invention is based on the autocorrelation function, and it is characterized in that the time interval between the largest peak and the second largest peak in the signal autocorrelation function sequence is used as the estimation of the interval between the main rhythm of the signal, and the amplitude value of the second largest peak is used as A measure of the regularity of the segment signal. The invention can be used for on-site analysis of heart electrical activity in animal experiments; it can also be used for assisting clinical diagnosis. Since the present invention adopts an integrated structure of collection and analysis, the method used is simple and effective, and thus has the characteristics of wide applicability and strong real-time performance.

Description

Cardiac mapping signal analysis and processing device and method

technical field

The invention relates to a biomedical signal analysis and processing device and method, in particular to an analysis and processing device and method for analyzing cardiac mapping signals.

Background technique

Cardiac mapping refers to the process of identifying, judging and locating arrhythmias starting from the electrical activity of the heart. The usual practice of heart mapping is: first, divide the region of interest on the heart into small points, place mapping electrodes or inject voltage-sensitive fluorescent dyes in each point, and confirm the physical location of each point; Secondly, the potential changes caused by the excitation of cardiomyocytes at each point are recorded; finally, by observing and comparing the changes of the mapping signals of each point in the region of interest during the arrhythmia and the correlation and difference between them, the researcher can carefully and in-depth Understand the electrophysiological mechanism of arrhythmia, and find the key factors closely related to the triggering and maintenance of arrhythmia. Furthermore, doctors can choose appropriate treatment methods and strategies based on these key factors. On the other hand, in order to observe the electrical activity of the heart in a more comprehensive and detailed manner, the current development of cardiac mapping technology presents a trend of "large number and high precision" of mapping sites. In recent studies, the order of magnitude of the mapped sites is generally above 100. This will inevitably bring massive heart mapping data. Therefore, designing relevant data analysis and processing devices and researching effective data analysis methods in order to extract key information from massive data has become an important topic in cardiac mapping technology.

In addition, rhythm analysis is an emerging direction of cardiac mapping signal analysis, which aims to study the rhythmic (that is, periodic) status of the cardiomyocyte group corresponding to the mapping signal participating in the cardiac electrical activity. Among the results of rhythm analysis, the two most important attributes are the excitation interval (or frequency) and signal regularity of the dominant rhythm. The former reflects the rhythm with which the cardiomyocyte group participates in cardiac electrical activity with the greatest probability; the latter reflects whether the cardiomyocyte group is affected by multiple sources of myocardial excitation. Under normal circumstances, the sinoatrial node is the only part of the heart that emits electrical excitement, and all the cardiomyocytes in the heart participate in the process of electrical activity under its control. At this time, the cardiac mapping signal only reflects a single sinus rhythm. However, when certain arrhythmias occur, one or more sources of ectopic excitation may appear in the heart. Ectopic excitatory sources can also emit electrical excitation, and its excitation frequency is significantly higher than that of sinus excitation. At this time, sinus rhythm and ectopic rhythm act together on the heart, causing the cardiac muscle cells to appear in a disordered state. This state will also be reflected in the cardiac mapping signal. Therefore, doctors or researchers can start from the mapping signal, find out and locate the ectopic drive in the heart during the arrhythmia through the method of rhythm analysis, so as to provide targets for further treatment.

Most of the existing rhythm analysis methods are based on Fourier transform, calculate the power spectrum of the mapping signal, and take the maximum peak in the power spectrum as the calculation result. However, because the Fourier transform will produce a large number of harmonic components, these harmonics may cause misjudgment of the analysis results; on the other hand, the cardiac mapping signal itself contains various complex frequency components, which will also cause power The shift of the maximum peak of the spectrum affects the analysis effect. Practical applications also show that the rhythm analysis method based on Fourier transform has good results only for weak rhythmic, complex and irregular cardiac mapping signals; but for strong rhythmic cardiac mapping signals, the calculation results are often different from the real situation There is a big discrepancy.

Contents of the invention

In order to solve the above-mentioned problems in the prior art, the purpose of the present invention is to provide a cardiac mapping signal analysis and processing device and method, especially a device and method for analyzing the rhythm state of the cardiac mapping signal.

The present invention is characterized by the integration of data collection and analysis, wide applicability and strong real-time performance. The invention can be used for on-site analysis of the electrical activity of the mapped heart in animal experiments; it can also be used for assisting clinical diagnosis.

The heart mapping signal analysis and processing device proposed by the present invention is composed of a mapping electrode 1, a multi-stage amplifier 2, a data acquisition card 3, an acquisition module 4, a signal analysis and processing unit 5, and an output display device 11. Stage amplifier 2, data acquisition card 3, acquisition module 4 and signal analysis and processing unit 5 are connected sequentially, and the output terminals of acquisition module 4 and signal analysis and processing unit 5 are respectively connected to output display device 11, wherein:

The mapping electrode 1 is used to place the region of interest on the heart;

The multi-stage amplifier 2 amplifies the weak ECG mapping signal from the mapping electrode 1 to an amplitude suitable for subsequent data acquisition card 3 acquisition, and filters out unnecessary frequency components in the signal;

The data acquisition card 3 samples the amplified ECG mapping signal, converts it into a digital signal, and stores it in the data buffer of the acquisition card;

The acquisition module 4 reads the cardiac mapping data in the acquisition card data cache into the internal memory, and regularly saves it as a data file;

The signal analysis and processing unit 5 analyzes and processes the ECG mapping data;

The output display device 11 is used for displaying the waveform and analysis processing results of the cardiac mapping data.

In the present invention, the signal analysis and processing unit 5 is composed of a preprocessing module 6, an exciting moment extraction module 7, a frequency domain analysis module 8, a time domain analysis module 9 and a nonlinear analysis module 10, the preprocessing module 6, the exciting moment extraction module Module 7, time-domain analysis module 9 are connected successively, and the output end of preprocessing module 6 is respectively connected frequency-domain analysis module 8 and nonlinear analysis module 10, and frequency-domain analysis module 8, time-domain analysis module 9 and nonlinear analysis module 10 The output terminals are respectively connected to the output display device 11; the preprocessing module 6 is used to remove external noise and interference superimposed in the cardiac mapping signal; the exciting moment extraction module 7 is designed to extract the excited moment of its corresponding cardiomyocyte group from the cardiac mapping signal The time-domain analysis module 9 analyzes the time-domain characteristics of the signal; the frequency-domain analysis module 8 analyzes the frequency-domain characteristics of the signal; the nonlinear analysis module 10 extracts more complex nonlinear information from the signal.

In the present invention, the mapping electrodes may be flexible electrodes or the like.

In the present invention, the nonlinear analysis module 10 includes a rhythm analysis unit 12 for analyzing the rhythm state of the cardiac mapping signal.

In the present invention, the rhythm analysis unit 12 adopts the autocorrelation function sequence peak method: the time interval between the largest peak and the second largest peak in the signal autocorrelation function sequence is used as the estimation of the main rhythm excitation interval of the signal, and the second The amplitude value of the large peak is used as a measure of the regularity of the segment signal.

In the present invention, mapping electrode 1.1, multistage amplifier 2 and data acquisition card 3 are realized by hardware circuit; Acquisition module 4 and signal analysis processing unit 5 can be realized on computer or DSP; Output display device 11 then can select liquid crystal for use screens, computer monitors or alarms etc.

The present invention proposes a heart mapping signal analysis and processing method, in particular a rhythm analysis method suitable for animal experiment sites or clinical applications. The method is based on the autocorrelation function of the cardiac mapping signal, and its principle is that the autocorrelation function of the periodic signal is also a periodic signal, and the period of the autocorrelation function is consistent with the signal period. As mentioned earlier, during certain arrhythmias, ectopic sources of excitation other than the sinoatrial node may be present in the heart. At this time, the cardiac mapping signal can be regarded as the superposition and reconstruction of the sinus rhythm signal and the ectopic rhythm signal according to specific rules. Therefore, the autocorrelation function of the mapping signal is closely related to the rhythm characteristics (period, signal amplitude) of the two rhythm signals. Therefore, we can deduce the current rhythm state of the mapping signal from the autocorrelation function of the signal.

The heart mapping signal analysis processing method that the present invention proposes, concrete steps are as follows:

a. Collect cardiac mapping data from animal or human hearts;

b. Select the mapping site and time segment of interest, and send the data to the signal analysis and processing unit;

c. Preprocess the cardiac mapping data to eliminate various interference and noise;

d. Perform rhythm analysis on the signal of each mapping site, and calculate its autocorrelation function sequence one by one. The calculation formula is as follows:

$\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}}\underset{\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span>$

Where x is the mapping signal, τ is the relative time displacement, n is the signal number;

e. Normalize the autocorrelation function sequence;

f. Search for the largest peak and the second largest peak in each normalized autocorrelation function sequence, and use the time interval between the largest peak and the second largest peak as an estimate of the excitation interval of the dominant rhythm of the signal, and the amplitude of the second largest peak The value is used as a parameter to measure the regularity of the signal (the larger the amplitude, the more regular the signal);

g. For a single mapping site, by observing the envelope of its signal autocorrelation function sequence, it can be deduced that the electrical activity of cardiomyocytes at this site is affected by several rhythms, which one is the main one;

h. For the mapping area of interest, a pseudo-color map or a three-dimensional histogram can be drawn according to the activation interval and regularity of the dominant rhythm of each point in the area, so as to intuitively reflect the distribution of various exciting rhythms on the heart during arrhythmia.

In the present invention, the excitation time extraction module can be invoked when studying the propagation direction of myocardial electrical excitation, that is, to analyze the time sequence of myocardial cell group excitation at each mapping site, and the calculation results can be used for comparison with the rhythm analysis results.

Compared with the prior art, the present invention has the following beneficial effects:

1. Combining the acquisition device with the analysis and processing system, the analysis and processing method adopted is simple and effective, so it can realize on-site analysis in animal experiments or clinical treatment;

2. The rhythm analysis method based on the autocorrelation function has stronger adaptability, and can have good analysis results under normal heart rhythm and during arrhythmia. Therefore, this method can be used for detection in surgery and long-term study of arrhythmia mechanism.

Description of drawings

Fig. 1 is the structural representation of device of the present invention;

Fig. 2 is a schematic structural view of the device of the present invention applied to epicardium mapping animal experiment example 1;

Fig. 3 is the working flow diagram of the method of the present invention applied to epicardium mapping animal experiment embodiment 1;

Fig. 4 is a schematic diagram of the operation result of the method of the present invention.

Numbers in the figure: 1 is the mapping electrode, 2 is the multi-stage amplifier, 3 is the data acquisition card, 4 is the acquisition module, 5 is the signal analysis and processing unit, 6 is the preprocessing module, 7 is the exciting moment extraction module, 8 is the frequency Domain analysis module, 9 is a time domain analysis module, 10 is a nonlinear analysis module, 11 is an output display device, 12 is a rhythm analysis unit.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Embodiment 1: As shown in Figure 1, the heart mapping signal analysis and processing device proposed by the present invention includes: a set of mapping electrodes 1, which are used to collect heart mapping signals from the site of interest in the heart; a set of multi-stage amplifiers 2, Its input terminal is connected to the end of the mapping electrode 1 via a cable, aiming at amplifying the millivolt-level heart mapping signal to the volt level, while filtering out unnecessary frequency components in the signal; a data acquisition card 3, the input terminal is connected to Input the output of the amplifier 2, used for sampling the analog ECG mapping signal, analog-to-digital conversion, and store it in the data cache of the acquisition card 3; a set of acquisition modules 4, regularly read from the data cache of the acquisition card 3 Cardiac mapping data, and save as data file; A signal analysis and processing unit 5, comprises modules 10 such as preprocessing 6, excited moment extraction 7, frequency domain analysis 8, time domain analysis 9 and nonlinear analysis, is used for collecting On-line or off-line analysis and processing are performed on the ECG mapping signals received; an output display device 11 is used to display the analysis and processing results. The mapping electrode 1, multi-stage amplifier 2, and data acquisition card 3 in the device are implemented by hardware; the acquisition module 4 and the signal analysis and processing unit 5 can be implemented on a computer or DSP; the two parts are connected by a USB data line; the output display device 11 is optional Any of LCD screen, computer monitor or alarm etc. When working, the signal analysis and processing unit reads a piece of heart mapping data from the memory or data file according to the operator's preset; firstly, it performs preprocessing to eliminate the noise interference in the signal; secondly, it extracts the myocardial cell excitation moment in the signal information; again, call one or more analysis processing units in the analysis module according to the setting; finally, the analysis result is transmitted to the output display device, and presented in the form of a pseudo-color map or a three-dimensional histogram.

Fig. 2 is an embodiment of the present invention used in epicardium mapping animal experiments. In this example, the mapped region on the heart is the epicardium (ie, the outer surface of the heart). The mapping electrode 1 is sutured to the epicardium under the premise of surgical thoracotomy; the magnification of the multi-stage amplifier 2 is usually selected to be 500-2000 times, and the effective frequency range is 3-600 Hz; the sampling frequency of the data acquisition card 3 is 2000 Hz. To ensure real-time processing, the signal analysis and processing unit 5 usually only performs rhythm analysis 12 at the animal experiment site. Its workflow is as follows: firstly, preprocessing 6 is performed on the cardiac mapping data in the internal memory; secondly, the preprocessed data is sent to the rhythm analysis unit 12 to perform calculations such as autocorrelation functions; finally, the rhythm analysis results are respectively dominated by The rhythm distribution map and the signal regularity distribution map are output to the display device 11 ; the exciting moment extraction 7 is an optional module, and its operation results can be used for comparison with the results of the rhythm analysis 12 .

As shown in Figure 3, when the method of the present invention performs rhythm analysis on the experimental data in the epicardium mapping animal experiment, its workflow is:

1. The heart mapping signal is collected from the outer surface of the animal heart by the device of the present invention, and converted into a digital form;

2. Select the data matrix to be analyzed from the obtained data according to the mapping site of interest and the mapping period set in the preset parameters (the length is usually 5-20 seconds) (the data of one mapping site is one row) ;

3. Preprocess the data to be analyzed;

4. Calculate the autocorrelation function row by row on the preprocessed data matrix (the range of relative displacement is usually 0-2 seconds), and after normalization, obtain the autocorrelation sequence;

(If necessary, the distribution of autocorrelation sequences can be plotted site by site to analyze the rhythmic state of excitation of the corresponding cardiomyocyte population)

5. Search for the positions of the largest peak and the second largest peak in the autocorrelation function sequence, use the interval between the two peaks as an estimate of the signal-dominant rhythm excitation interval, and use the amplitude of the second largest peak as an index to measure the regularity of the signal;

6. After recording the rhythm status of all the signals at the mapping sites, draw the dominant rhythm distribution map and regularity distribution map in the region of interest in the form of a pseudo-color map.

Fig. 4 is a schematic diagram of the analysis results of the method of the present invention applied to the epicardial animal experiment. The experimental data is taken from the right atrial appendage in the heart of the animal, and the data time period is 20 seconds after the animal has atrial fibrillation (a complex arrhythmia). The schematic diagram of the analysis results is drawn in the form of a pseudo-color map, and the numerical range represented by each color is marked on the right side of the map. As mentioned previously, the interval between major and minor autocorrelation peaks is an estimate of the inter-excitation interval of the dominant rhythmic portion of the signal. Figure 4a shows that there are high-frequency excitations in the two regions of AB (excitation interval<100ms); while the excitation interval of C region is obviously longer than that of AB region. This phenomenon is consistent with the physical position relationship between the right atrial appendage electrode (B sheet) and the sinoatrial node (the excitation interval of sinus rhythm is usually significantly longer than that of the ectopic source) and the stimulating electrode: in animal experiments, B The upper left part of the slice is closest to the superior vena cava, and the sinoatrial node is just near the boundary sulcus at the junction of the superior vena cava and the right atrium; and the approximate position of the stimulating electrode is shown as '0' in the figure. Figure 4b further reflects the differences in the three regions of ABC. The magnitude of the second largest autocorrelation peak is a measure of the regularity of the signal. The signal regularity in area C is the lowest, A is the highest, and B is relatively low. Fig. 4c is an isochronous diagram of area A (the analysis result of the excitation moment extraction module 7), and it can be found that the signal propagates to the lower left in area A. Comparing the three pictures, it can be confirmed that there may be an ectopic excitation source near the stimulating electrodes. Area A is a dominant path for the transmission of excitation from the ectopic source on the heart of the animal when atrial fibrillation occurs, while area C is simultaneously stimulated by the sinoatrial Effects of offshoot excitation and uplink excitation from ectopic sources.

Claims (4)

1. A heart mapping signal analysis and processing device, consisting of a mapping electrode (1), a multi-stage amplifier (2), a data acquisition card (3), an acquisition module (4), a signal analysis and processing unit (5) and an output display The device (11) is composed of a mapping electrode (1), a multi-stage amplifier (2), a data acquisition card (3), an acquisition module (4) and a signal analysis and processing unit (5) connected in sequence, and the acquisition module (4 ) and the output terminals of the signal analysis and processing unit (5) are respectively connected to the output display device (11), wherein: A mapping electrode (1) is used to place the region of interest on the heart; The multi-stage amplifier (2) amplifies the weak ECG mapping signal from the mapping electrode (1) to an amplitude suitable for subsequent data acquisition card (3) acquisition, and filters out unnecessary frequency components in the signal; The data acquisition card (3) samples the amplified ECG mapping signal, converts it into a digital signal, and stores it in the data cache of the acquisition card; The acquisition module (4) reads the cardiac mapping data in the data cache of the acquisition card into the internal memory, and regularly saves it as a data file; The signal analysis and processing unit (5) analyzes and processes the ECG mapping data; the signal analysis and processing unit (5) consists of a preprocessing module (6), an exciting moment extraction module (7), and a frequency domain analysis module (8) , time-domain analysis module (9) and nonlinear analysis module (10), the preprocessing module (6), exciting moment extraction module (7), and time-domain analysis module (9) are sequentially connected, and the preprocessing module (6) The output terminals are respectively connected to the frequency domain analysis module (8) and the nonlinear analysis module (10), and the output terminals of the frequency domain analysis module (8), the time domain analysis module (9) and the nonlinear analysis module (10) are respectively connected to the output display The device (10); the preprocessing module (6) is used to remove external noise and interference superimposed in the cardiac mapping signal; the exciting moment extraction module (7) is designed to extract the excited moment of its corresponding cardiomyocyte group from the cardiac mapping signal The time-domain analysis module (9) analyzes the time-domain characteristics of the signal; the frequency-domain analysis module (8) analyzes the frequency-domain characteristics of the signal; the nonlinear analysis module (10) extracts more complex nonlinear information from the signal; The output display device (11) is used for displaying the waveform and analysis and processing results of the cardiac mapping data. 2. The cardiac mapping signal analysis and processing device according to claim 1, characterized in that the nonlinear analysis module (10) includes a rhythm analysis unit (12) for analyzing the rhythm state of the cardiac mapping signal. 3. The heart mapping signal analysis and processing device according to claim 2, characterized in that the rhythm analysis unit (12) adopts the autocorrelation function sequence peak method: the maximum peak and the second largest peak in the signal autocorrelation function sequence The time interval between the peaks was used as an estimate of the main rhythmic excitation interval of the signal, and the amplitude of the second largest peak was used as a measure of the regularity of the signal. 4. The cardiac mapping signal analysis and processing device according to claim 1, characterized in that the output display device (11) is any one of a liquid crystal screen, a computer monitor or an alarm.

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