CN1124824C - Dynamic electrocardiographic assignment test method and its equipment - Google Patents

Abstract

The invention relates to a dynamic electrocardiogram mapping method and a device thereof. Electrode arrays made of flexible printed circuit sheets are used as mapping electrodes to obtain monopolar ECG signals, which are then multiplexed to obtain bipolar signals. Analyze and process the above signals, detect feature points, and generate dynamic isochronous mapping diagrams, wave diagrams and vector diagrams, etc. The present invention can not only be used for the ECG mapping of conventional ectopic excitation and ectopic conduction, but also be applicable to ECG mapping in the case of atrial fibrillation and other cardiac sources of excitation and variations and disorder of multipath conduction, and has clinical advantages. Significance.

Description

Dynamic ECG mapping method and device thereof

The invention relates to a method and a device for cardiac potential mapping.

Conventional ECG mapping is used to reveal the sequence of excitation of various parts of the heart and the conduction process of the excitation, so as to find out the abnormal conduction pathway and the source of ectopic excitation during arrhythmia. It is an important tool in the study of cardiac electrophysiology. Clinically, ECG mapping can be divided into endocardial mapping and epicardial mapping. The former uses the cardiac catheter electrode to fix a catheter electrode somewhere in the heart as a reference point, and uses another or several catheters to detect the arrival time of the depolarization wave (that is, the excitation transmission wave) at different positions, and then compares the arrival time of each point. Sequentially, on the plane, connect the points representing the simultaneous arrival of depolarization waves to form an isochronous mapping map. Because the position that the catheter can reach is restricted by objective conditions, certain parts of the heart (such as the left atrium and left ventricle) are often difficult to map. In addition, since catheters are inserted through superficial blood vessels, their number is limited. Therefore, multi-site exploration often needs to be carried out in batches and time-sharing. This requires that the heartbeat must be regular and synchronizable. It is often impossible to do it in arrhythmia, especially in atrial fibrillation (AF), the activity of the atrium is disordered and non-repetitive. In the latter, during thoracotomy, multi-point electrodes are attached to the outer surface of the heart (adventitium), and the depolarization waves of the heart are simultaneously detected through the electrode array elements, and an isochronous mapping map can be made. Its advantage is that it eliminates the need for successive comparisons using a reference point, and can map depolarization waves to single heartbeats (heartbeats), whether they are normal (sinus) or abnormal (ectopic premature beats) the transfer process. However, in the case of atrial fibrillation, the sources of ectopic excitation are multi-source in space and non-repetitive in time. Therefore, the above-mentioned isochronous mapping diagram, which is usually used to characterize the depolarization pathway of a single heartbeat, can no longer express the ectopic excitation and abnormal propagation of atrial fibrillation, and a new mapping method and system is necessary. In addition, the conventional ECG mapping system adopts the method of bipolar detection, that is, a pair of electrodes (bipolar) is used to measure the potential difference of a certain point on the cardiac watch. This method can accurately detect the electrical activity between the electrode pairs, while ignoring the detection of the space between the electrode pairs. If depolarization or conduction occurs in a small area between the two electrode pairs, it is possible that two adjacent pairs of electrodes are If it cannot be detected, it will affect the comprehensiveness and accuracy of detection. Moreover, the number of electrode points of this kind of mapping electrode must be large enough (twice the number of detection channels), and its electrode lead wires are only a large number, which are relatively large in size, easily cause confusion and breakage, and bring trouble to use. In addition, the electrode cost is relatively expensive.

The purpose of the present invention is to propose a dynamic ECG mapping method and device capable of characterizing the distribution and variation of cardiac ectopic excitation and ectopic conduction, and the method and device are easy to use and cheap.

The ECG mapping method proposed by the present invention adopts the m×n electrode array evenly arranged on the flexible insulating substrate as the mapping electrode, which is attached to the epicardium to obtain the ECG signal, and the electrode signals of each path are transmitted through the amplifier. Amplify the same multiple, and then adopt multi-channel synchronous sampling and high-speed A/D conversion method to convert the electrode signal into a digital signal and send it to the computer, and then perform relevant analysis and processing.

The mapping electrode die used in the present invention is a flexible printed circuit sheet in which electrode points are arranged in an m×n array, and the distance between electrodes is kept constant without losing flexibility. Generally, 4≤m, n≤20. m is the number of rows of the electrode array, and n is the number of electrode points in each row. The electrode array and electrode wires form an integrated structure through a flexible circuit sheet, as shown in Figure 1. The electrode leads can be connected with the corresponding connectors.

The above-mentioned electrode array can adopt the following two better arrangements:

One is the square array form, that is, the electrode points of two adjacent rows of the electrode array are vertically aligned up and down, forming a row and column form, and the row and column spacing are the same, as shown in Figure 2. The other is the honeycomb array form, that is, the electrode points in two adjacent rows are staggered at an angle of 60 degrees up and down, and the adjacent two electrode points in the upper row and the corresponding electrode points in the lower row form an equilateral triangle. In this electrode array, there are 6 equidistant adjacent electrode points on the top, bottom, left, and right sides (except for the edge part) of any electrode point, forming a regular hexagon, which looks like a honeycomb, as shown in Figure 3.

The above-mentioned electrode array can obtain m×n unipolar electrical signals, that is, the unipolar mapping signals at each electrode point can be obtained. In addition, it is also desirable that two adjacent electrode points in the array form a bipolar lead to obtain a bipolar signal. For the square array form, the number of bipolar signals is k=m(n-1)+(m-1)n=2mn-m-n. For the cellular array form, the number of bipolar signals is k=m(n-1)+(m-1)(2n-1)=3mn-2(m+n)+1. In this way, through the multiplexing of the electrode signals, the utilization rate of the electrodes is greatly improved, the number of lead wires of the electrodes is reduced, and a sufficient number of detection signals can be obtained by using a small number of electrodes. For example, when m=n=8, in the form of a square array, there are 8×8=64 unipolar signals, 2×8×8-8-8=112 bipolar signals, and a total of 176 signals. In the form of a cellular array, there are 64 unipolar signals, 3×8×8-2×(8+8)+1=161 bipolar signals, and there are 225 signals in total. However, if conventional bipolar mapping is used, only 32 bipolar signals can be obtained.

In order to further reduce the number of channel amplifiers, we also adopt the method of using the difference of the unipolar signal of two adjacent electrode points to replace the bipolar measurement. For a square array of electrodes, let {US _ij (t)} be the unipolar signal of the electrode point in row i and column j at time t (abbreviated as {U _ij }), use BxS _ij (t) and ByS _ij (t) represents the bipolar signal between two adjacent electrodes in the horizontal and vertical directions at the electrode point at i and j (abbreviated as {B _ij }), then:

Using the unipolar and bipolar signals of the electrocardiogram obtained above, the present invention can analyze and map feature points. It is known from the principle of cardiac electrophysiology that when the depolarization wave (DW) propagates, when the wave front reaches a certain electrode, the potential of the electrode rises, and the potential returns to the basic value after passing through. Once DW passes, a potential deflection will appear on the electrode. Therefore, for a unipolar detection signal, its peak point represents the arrival time of DW; for a bipolar detection signal, a DW passage is represented as a "N ” type of potential deflection, the zero-crossing point between its double peaks corresponds to the moment when DW reaches the midpoint of the pair of electrodes. According to this principle, the characteristic points representing the arrival time of DW in each channel are detected: the peak point of the unipolar signal and the zero crossing point between the double peaks of the bipolar signal. Let UT _ij (t _k ), BxT _ij (t _e ) and ByT _ij (t _g ) denote the feature point sets of unipolar signal, bipolar signal x direction and bipolar signal y direction respectively (abbreviated as {T _ij } ), k, e, g<N, where N is the data length. For the detection data with a time length of 30 seconds, if the sampling rate is 2.5KS/S, its length N is about 30×2.5k=75k.

According to the above preprocessing results, the present invention can further express dynamic ECG mapping in the following three ways.

1. Dynamic isochronous mapping map. Within a certain sampling period (such as 30 seconds), the detected feature point data (including unipolar signal UT _ij (t _k ), bipolar signal X direction data B _x T _ij (t _l ), bipolar signal Signal y-direction data ByT _ij (t _g ) is interpolated to obtain the value of the spatial position that DW arrives at the initial moment and certain moments later, such as 2ms, 4ms, 6ms... and marked in the m×n electrode column In the spatial distribution diagram of the array, connect the spatial points representing the same time (such as 2ms, 4ms, 6ms...etc.) Time-mapping map. By inputting feature point data in time order and making a map, a dynamic isochronous-mapping map that changes frame by frame can be obtained, as shown in Fig. 4 to Fig. 5.

2. Wave chart. Display the planar position of the electrode array on the screen. The arrays of unipolar and bipolar signals {US _ij (t)} and {BS _ij (t)} obtained by sampling at the same time t are divided into dimming or pseudo-color (different amplitude values can be represented by different colors) for each Adjust the brightness or color of the corresponding electrode points, and then perform functional interpolation on the space between the electrode points, and then continuously obtain the wave-like response ECG potential excitation distribution and the fluctuation map of the propagation path, as shown in Figure 6. This wave diagram contains all the information of the amplitude and phase, dynamically reflects the propagation process of the depolarization wave of the heart, makes the electrical activity of the heart surface intuitive (visualized and can display the evolution process in slow motion, and can be used as a study of atrial fibrillation electrophysiology and Analytical basis for clinical treatment.

3. Vector field diagram and vector field scatter diagram. Utilize the obtained bipolar signal array B _x S _ij (t) and By _y S _ij (t), obtain the angle and size (i.e. propagation direction and propagation speed) of the depolarization wave entering this position according to the trigonometric function relationship, and Mark the vector field distribution diagram at this moment on the electrode array diagram. As shown in Figure 7 and Figure 8. The magnitude and angle of the vector at a certain moment at the electrode point i and j can be obtained by the following formula: $\left|\stackrel{\&Right\; Arrow;}{V}\right|=\sqrt{B_x{S}_{\mathrm{ij}}^2\left(t\right)+B_{\mathrm{the\; y}}{S}_{\mathrm{ij}}^2\left(t\right)}$

α = arctg ⁻¹ (B _y S _ij (t)/B _x S _ij (t)).

The sagittal field distribution map not only shows the excitation status of the myocardium at each point at the same time, but also mainly shows the position of the wavefront and the moving direction of DW, especially for the mapping of atrial fibrillation, it can show the position of the myocardium participating in the propagation of DW at each point and the spatial correlation of myocardial fiber depolarization everywhere in AF.

Since the vector field distribution diagrams at different time t are different, they are not repeated during AF. In order to have an overall and statistical understanding of the degree of myocardial participation in AF and the way of participation (direction of conduction) at each point, the vector end (representing the Vector size and direction) are displayed in a scatter plot. The vector field scatter diagram expresses the extent (vector amplitude) and the main tendency of the myocardium to participate in the conduction of ECG signals in the observed time period. It is of great significance to the study of electrophysiological mechanism and clinical treatment of AF.

It can be seen from the above that the present invention is a multi-mode dynamic mapping method for the whole area of ECG. Corresponding to this method, the present invention designs a corresponding mapping device. The device is composed of m×n flexible array mapping electrodes (4≤m, m≤20), amplifier, A/D conversion card, main computer, large-screen display, high-speed printer and other parts. As shown in Figure 9. Here, the m×n flexible array electrode sheet is used to map the potential signal of the epicardium. The m×n amplifiers have the same magnification and the same filtering characteristics, and are used to amplify the electrical signals of each channel separately. The magnification can be adjusted within the range of 100 times, 250 times, 500 times, 1000 times, 5000 times, etc. The A/D conversion card converts the electrocardiographic signals obtained by synchronous sampling from various channels into digital signals (for example, 12 bits), and then feeds them to the host computer through the bus for analysis and processing. In addition to being used for system control to collect real-time signals and store various data, the main computer also performs fast post-processing, including calculation of bipolar signals, detection of feature points, generation of dynamic isochronous diagrams, generation of wave diagrams, Generation of vector field plots and vector field scatter plots, etc. The large-screen display is used to display dynamic mapping diagrams, fluctuation diagrams, vector distribution diagrams, etc. under the control of the host computer. The high-speed printer can print out the detection data and relevant mapping graphics.

Animal and clinical tests are carried out by using the mapping instrument made by the invention, and it is confirmed that dynamic electrocardiographic mapping is feasible, and the aforementioned three kinds of mapping quantities are observed and recorded.

The mapping method and mapping device proposed by the present invention are not only meaningful for the localization and transmission path of excitement in the case of regular heart rhythm and fixed conduction path, but also can map the source of premature beats and ectopic conduction. It is also suitable for mapping the situation of atrial fibrillation. It comprehensively displays the amplitude and phase information of the whole area (such as 5×5cm) and the transmission path for a long time (such as 30 seconds) on the dynamic map, which can be visually observed, analyzed and judged. The degree of myocardium participation in depolarization (frequency and intensity) and the correlation with the adjacent myocardium were statistically processed. In addition, the present invention adopts the electrode multiplexing method, which not only supplements a large amount of bipolar information in addition to monopolar mapping, but also collects information in the whole area, and any excitation source, transmission or blockage in the observed range will not missing, so it is a full-information map and improves the mapping accuracy. At the same time, the electrode processing is easy, the wiring is simple, the number of amplifiers is also small, the cost is greatly reduced, and the use is very convenient.

As long as the mapping electrodes are replaced and the display mode is slightly modified, the present invention can also be used for endocardial mapping. For example, the use of basket-shaped endocardial catheter mapping electrodes can simultaneously perform multi-point sampling on the potential changes of each point in the endocardium, and can map the isochronous diagram in the atrium (or in the ventricle) in a three-dimensional (stereoscopic) manner. , Fluctuation graph display and print out. Undoubtedly, this is very beneficial to electrophysiological research.

Description of drawings

Figure 1 is a structural diagram of a flexible mapping electrode.

Figure 2 shows the array of electrode points.

Figure 3 shows the honeycomb arrangement of electrode points.

Fig. 4 is an isochronous diagram during sinus rhythm measured by the present invention. Among them, Figure 4(a)-(f) are the isochronous diagrams at t=4ms, 8ms, 12ms, 16ms, 20ms, and 24ms in turn.

Fig. 5 is an isochrone diagram of ventricular fibrillation measured by the present invention, wherein Fig. 5 (a) to (f) are sequentially isochrone diagrams at t=20ms, 40ms, 60ms, 80ms, 100ms, 120ms.

Fig. 6 is the wave diagram of right ventricle depolarization in sinus rhythm measured by the present invention, wherein Fig. 6(a)-(o) are the wave diagrams at t=oms, 2ms, 4ms, . . . , 28ms.

Fig. 7 is a depolarization vector diagram and a depolarization vector scatter diagram during sinus rhythm measured by the present invention. Among them, Fig. 7(a) is a multi-channel ECG record during sinus rhythm, Fig. 7(b) is a depolarization sagittal field diagram, and Fig. 7(c) is a depolarization sagittal field scatter diagram.

Fig. 8 is a depolarization sagittal diagram and a depolarization sagittal field scatter diagram during ventricular fibrillation measured by the present invention. Among them, Figure 8(a) is a multi-channel ECG record during atrial fibrillation, Figure 8(b) is a depolarization vector diagram, and Figure 8(c) is a depolarization vector field scatter diagram.

Fig. 9 is a structural block diagram of the mapping system of the present invention.

Fig. 10 is a program block diagram of feature point detection calculation in the present invention. Among them, Fig. 10(a) is for detecting the peak point of the unipolar signal, and Fig. 10(b) is for detecting the zero-crossing point of the bipolar signal.

Fig. 11 is a calculation program block diagram of dynamic isochrone diagram generation in the present invention.

Fig. 12 is a calculation program block diagram of wave diagram generation in the present invention.

Fig. 13 is a program block diagram for generating a depolarization vector field diagram and a depolarization vector field scatter diagram according to the present invention. Among them, Fig. 13(a) is a generated vector field diagram, and Fig. 13(b) is a generated vector field scatter diagram.

Numbers in the figure: 1 is the electrode array, 2 is the lead wire of each electrode, 3 is the flexible printed circuit, 4 is the single electrode point, 5 is the bipolar center point, 6 is the connector, and 7 is the protective film layer.

As an example, the electrode array of the mapping system is m×n=8×8, the size of the electrode sheet is 5×5cm, the diameter of each electrode point is 2.0mm, and the distance between them is 3.0mm. The electrode surface is plated with gold as a protective layer, and respectively It is led out by a thin wire of 0.1mm. The flexible electrode is connected with the amplifier through a connector. For the 8×8 electrode array, there are 66 independent amplifiers in total. Among them, 64 channels are used to amplify the ECG signals measured by 64 electrodes, and the other 2 channels are used to amplify the body surface ECG. Each amplifier is equipped with a 40-500HZ 4th-order Bessel band-pass filter and a 50HZ point filter. All amplifiers adopt floating technology, common mode rejection ratio CMRR ≥ 100db; input impedance ≥ 5MΩ; application side and power supply side voltage ≥ 4000VAC; leakage ≤ 10μA.

Figures 10-13 show the block diagrams of the main computer's calculation and processing programs for the detection of feature points, the generation of dynamic isochronous diagrams, the generation of wave diagrams, the generation of vector field diagrams and vector field scatter diagrams.

For the display of 66 ECG waveforms, a split-screen (16 channels per screen) rolling display method is adopted, and a 20-inch color display is used to perform a full-screen scrolling format under a 1024×768 precision windows operation interface. Scrolling speed is adjustable from 100mm/s to 800mm/s. Both waveform display and dynamic mapping can be frozen for observation. The waveform record can be sprayed with a wide width of 320mm.

Claims (6)

1. A dynamic ECG mapping method, characterized in that an m×n flexible electrode array is used as the mapping electrode to obtain ECG unipolar signals, and the amplifiers amplify the signals of each electrode by the same multiple, and then use multiple synchronous Sampling and high-speed A/D conversion method to convert electrode signals into digital signals, where 4≤m≤20, 4≤n≤20, m is the number of electrode array rows, n is the number of electrode points in each row; Two adjacent electrode points form a bipolar lead, and the differential electrical signals of two adjacent single electrodes are calculated to obtain bipolar signals, which are then analyzed and processed. 2. The dynamic electrocardiographic mapping method according to claim 1, characterized in that all peak points of a certain inner unipolar signal and all zero-crossing points of a bipolar signal on the X direction and the Y direction are detected to obtain each The set of feature points at the arrival time of the depolarization wave at the electrode point. 3. The dynamic ECG mapping method according to claim 2, characterized in that the feature point data is interpolated to obtain the value of the spatial position corresponding to an integer time such as 2ms, 4ms, 6ms, ..., and Mark in the spatial distribution diagram of the m×n electrode array, and then connect the spatial points representing the same time in sequence to obtain an isochronous mapping map, and input the feature point data in sequence in time order to obtain a dynamic isochronous mapping map . 4. The dynamic ECG mapping method according to claim 1, characterized in that within a certain sampling time period, the unipolar and bipolar signal data sampled at a certain moment are respectively modulated by luminance or false color Adjust the brightness or color code modulation of each corresponding electrode point, and then interpolate the area between the electrode points to obtain an image representing the amplitude and spatial distribution of the depolarization wave front at that moment, and continuously input the above data to obtain the reflected ECG Fluctuation diagram of potential excitation distribution and propagation path. 5. The dynamic ECG mapping method according to claim 1, characterized in that the angle and amplitude at which the depolarization wave enters the position of the electrode point is obtained by using the data of the bipolar signal in the X direction and the Y direction, Mark the vector field distribution diagram at this moment on the electrode array diagram; for a time period, the vector ends of each point are expressed in a scatter way successively to form a vector field scatter diagram. 6. A dynamic ECG mapping device, characterized in that it consists of m×n flexible array mapping electrode dies 4≤m≤20, 4≤n≤20, multi-channel amplifier, A/D conversion card, main computer , a large-screen display, and a high-speed printer are connected by a circuit. The electrode sheet is connected to the amplifier through a connector. The ECG signal detected on the electrode is amplified by the amplifier, converted into a digital signal by the A/D conversion card, and fed to the main computer by the bus. , the main computer implements the calculation of bipolar signals, the detection of characteristic points, the generation of dynamic isochronous diagrams, the generation of wave diagrams, and the generation of vector field distribution diagrams, and is connected with a large-screen display.

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