Downsampling method and system for electrocardiogram data

Abstract

The invention discloses a downsampling method and system for electrocardiogram data, and belongs to the field of electrocardiogram data sampling. The down-sampling method for the electrocardiogram data comprises the following steps: calculating a down-sampling factor according to an original sampling rate and a new sampling rate; grouping the original sampling data of the electrocardiogram according to the down-sampling factor; for each group of obtained original sampling data, the maximum value or the minimum value in the group is selected as new sampling data according to the data trend, and the down-sampling process from high-sampling-rate data to low-sampling-rate data is realized; a data selection method based on an electrocardiosignal trend is adopted, and down-sampling with data high-frequency characteristics reserved is achieved.

Description

Technical Field

[0001] The present invention belongs to the field of electrocardiogram (ECG) data sampling, and particularly relates to a downsampling method and system for ECG data. Background Art

[0002] ECG data refers to the digital data collected from an electrocardiogram (ECG) signal, which usually contains information related to the electrical activity of the heart. The ECG data mainly detects the current changes of the heart through electrodes and records the electrical activity of each part of the heart during each heartbeat. Since the electrical activity of the heart changes periodically, the ECG data usually appears as a series of waveforms or signals, and these signals can reflect the health status of the heart.

[0003] Under normal circumstances, in order to ensure accurate capture of the subtle changes in the ECG signal, the ECG signal acquisition usually needs to use a relatively high sampling rate (1000 SPS or higher). However, in the following application scenarios, it is necessary to use a low sampling rate (such as 125 SPS) to achieve certain functions: 1) Storage of long-term ECG data: For example, the storage of 30-day ambulatory electrocardiogram data. To save storage space, a low sampling rate is required to reduce the total data storage volume; 2) Analysis of long-term ECG data: For example, the analysis of 30-day ambulatory electrocardiogram data. Compared with a sampling rate of 1000 SPS, using 125 SPS can compress the analysis time to about one-eighth; 3) Real-time ECG data transmission at a low communication rate: For example, real-time ECG data acquisition based on Bluetooth communication. Subject to the low transmission rate of Bluetooth, a low sampling rate is required to reduce the amount of real-time transmitted ECG data; 4) Drawing of ECG waveforms on a low-resolution display device: When drawing an ECG on a computer screen, usually 1 millimeter of the ECG grid is represented by 5 pixels. At a paper speed of 25 mm / s, 1 pixel represents 8 milliseconds. At this time, the ECG display sampling rate is 125 SPS.

[0004] In the existing downsampling methods, usually two methods of equal-interval data extraction and multi-point data averaging are adopted. Equal-interval data extraction means that the sampling points are extracted at fixed time intervals, that is, sample points are uniformly selected from the original data; multi-point data averaging means that the original signal is grouped according to a certain window size (that is, multiple consecutive points), and the sampling points within each group are averaged to obtain a sampling point representing the group. However, both of these two downsampling methods have the defect of loss of high-frequency characteristics of the data. The specific defects caused in the ECG waveform are: 1) Loss of pacing pulse signals or severe attenuation of the amplitude of pacing pulse signals; 2) For the QRS complex with a relatively fast change, attenuation of the peak value of the high R wave or the valley value of the deep S wave. Therefore, a downsampling method for ECG data is proposed. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a method and system for downsampling electrocardiogram data, which solves the problems in the prior art.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A method for downsampling electrocardiogram data includes the following steps:

[0008] Calculate the downsampling factor according to the original sampling rate and the new sampling rate;

[0009] Group the original sampled data of the electrocardiogram according to the downsampling factor;

[0010] For each group of the obtained original sampled data, select the maximum or minimum value within the group according to the data trend as the new sampled data to achieve downsampling.

[0011] Further, the calculation formula of the downsampling factor is:

[0012]

[0013] Among them, the downsampling factor indicates how many original sampling points are reserved for one new sampling point.

[0014] Further, after grouping the original sampled data, the number of data points in each group of the original sampled data is equal to the value of the downsampling factor.

[0015] Further, during the downsampling process, the trend of the new sampled data is represented by TREND_FLAG. It is judged by obtaining two consecutive new sampled data. If the previous new sampled data is less than the next new sampled data, then TREND_FLAG is equal to 1, indicating an upward trend; otherwise, TREND_FLAG is equal to 0, indicating a downward trend. TREND_FLAG is continuously updated through the obtained new sampled data during the downsampling process.

[0016] Further, the step of selecting the new sampled data from each group of the original sampled data according to the data trend includes:

[0017] S31. For the first set of original sampling data, first find the maximum data MAX_VAL and its position MAX_POS within the group, as well as the minimum data MIN_VAL and its position MIN_POS. Then compare the sizes of MAX_POS and MIN_POS. If MAX_POS is greater than MIN_POS, it indicates that the data trend within the group is upward. The new sampling data Y_CUR is MAX_VAL, update the trend TREND_FLAG of the new sampling data to 1 and the previous point new sampling data PRE_VAL to MAX_VAL. Otherwise, it indicates that the trend is downward. The new sampling data Y_CUR is MIN_VAL, update TREND_FLAG to 0 and PRE_VAL to MIN_VAL.

[0018] S32. For the second set of original sampling data, first find the maximum value MAX_VAL and the minimum value MIN_VAL within the group, and then compare MIN_VAL and PRE_VAL. If MIN_VAL is greater than or equal to PRE_VAL, it indicates that the overall data trend is upward, and the new sampling data Y_CUR is MAX_VAL. If MIN_VAL is less than PRE_VAL, then continue to compare MAX_VAL and PRE_VAL. If MAX_VAL is less than or equal to PRE_VAL, it indicates that the overall data trend is downward, and the new sampling data Y_CUR is MIN_VAL. If MAX_VAL is greater than PRE_VAL, continue to judge through TREND_FLAG.

[0019] S33. If TREND_FLAG is equal to 1, it indicates that the data trend is upward, and the new sampling data Y_CUR is MAX_VAL, otherwise Y_CUR is MIN_VAL. If TREND_FLAG is equal to 0, it indicates that the data trend is downward, and the new sampling data Y_CUR is MIN_VAL.

[0020] S34. After the new sampling data Y_CUR is selected, update TREND_FLAG and PRE_VAL. First, update TREND_FLAG by comparing Y_CUR and PRE_VAL. If Y_CUR is greater than PRE_VAL, it indicates that the trend is upward, and TREND_FLAG is set to 1. If Y_CUR is less than PRE_VAL, it indicates that the trend is downward, and TREND_FLAG is set to 0. If Y_CUR is equal to PRE_VAL, TREND_FLAG remains unchanged. Then complete the update of PRE_VAL by assigning the value of Y_CUR to PRE_VAL. The update order of TREND_FLAG and PRE_VAL needs to be in the order of TREND_FLAG first and then PRE_VAL.

[0021] S35. For each subsequent set of original sampled data, repeat S32 - S34 for data selection to complete the downsampling process of the entire original sampled data.

[0022] Further, after grouping the original sampled data according to the downsampling factor, make the following judgment and selection based on the previous point data trend, the previous point sampling value, and the maximum and minimum values within the group:

[0023] 1) If the minimum value within the current group is greater than or equal to the previous point sampling value, then select the maximum value for the current sampling value, and set the current data trend to upward;

[0024] 2) If the maximum value within the current group is less than or equal to the previous point sampling value, then select the minimum value for the current sampling value, and set the current data trend to downward;

[0025] 3) If the maximum value within the current group is greater than the previous point sampling value and the minimum value within the current group is less than the previous point sampling value, then make a judgment based on the previous point data trend; if the previous point data trend is upward, then select the maximum value for the current sampling value, and set the current data trend to upward; if the previous point data trend is downward, then select the minimum value for the current sampling value, and set the current data trend to downward.

[0026] A downsampling system for electrocardiogram data, comprising:

[0027] A downsampling factor calculation module: Calculate the downsampling factor according to the original sampling rate and the new sampling rate;

[0028] An original sampled data grouping module: Group the original sampled data of the electrocardiogram according to the downsampling factor;

[0029] [[ID=......]] And a downsampling module: For each group of the obtained original sampled data, select the maximum or minimum value within the group according to the data trend as the new sampled data to achieve downsampling.

[0030] A computer storage medium stores a readable program that, when the program runs, can execute the above - mentioned downsampling method for electrocardiogram data.

[0031] An electronic device includes: a processor, a memory, a communication interface, and a communication bus. The processor, the memory, and the communication interface complete mutual communication through the communication bus;

[0032] The memory is used to store at least one executable instruction, and the executable instruction causes the processor to execute the operations corresponding to the above - mentioned downsampling method for electrocardiogram data.

[0033] A computer program product includes computer instructions, and the computer instructions direct a computing device to execute the operations corresponding to the above - mentioned downsampling method for electrocardiogram data.

[0034] Advantages of the present invention:

[0035] By adopting the method of data selection based on the trend of electrocardiogram signals, the present invention realizes downsampling while retaining the high-frequency characteristics of the data, and can assist medical staff in making accurate diagnoses in combination with other examination items. Brief Description of the Drawings

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0037] Figure 1 It is the flowchart of downsampling of electrocardiogram data of the present invention;

[0038] Figure 2 It is the schematic diagram of downsampling principle of the present invention;

[0039] Figure 3 It is the logic flowchart of downsampling data selection of the present invention. Detailed Embodiments

[0040] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0041] Embodiment 1

[0042] As Figure 1 shown, a method for downsampling electrocardiogram data includes the following steps:

[0043] S1. Calculate the downsampling factor according to the original sampling rate and the new sampling rate;

[0044] The original sampling rate refers to the original sampling rate of the electrocardiogram signal;

[0045] The new sampling rate refers to the target sampling rate at which the electrocardiogram signal needs to be downsampled;

[0046] The downsampling factor refers to the proportional relationship between the sampling rate (original sampling rate) of the original signal and the target sampling rate (new sampling rate) during downsampling; it indicates how many original sampling points are skipped before retaining one new sampling point. The downsampling factor is usually an integer, indicating that among every N consecutive original sampling points, only 1 sampling point is retained. The calculation formula is as follows:

[0047]

[0048] S2. Group the original sampled data of the electrocardiogram according to the downsampling factor calculated in S1, and the number of data points in each group is equal to the value of the downsampling factor;

[0049] As Figure 2 shown, without loss of generality, assume that the downsampling factor is 4, where X1 to X N represents the continuous electrocardiogram data of the original sampling. Every 4 original sampling data are divided into a group according to the downsampling factor. Then in S3, select each group of data according to the data trend, and use the obtained data as the data of the new sampling points (Y1 to Y M ), where

[0050] In this embodiment, the number of data in each group of the original sampling data should meet the condition of being equal to the downsampling factor. Therefore, this embodiment is only applicable to the case where the downsampling factor is an integer. When the downsampling factor is a decimal (non-integer), the method of upsampling by interpolation first by finding the common factor of the two sampling rates and then downsampling is not within the scope of discussion of this embodiment.

[0051] S3. For each group of original sampling data obtained in S2, select the maximum or minimum value within the group according to the data trend as the new sampling data to achieve downsampling.

[0052] As Figure 3 shown, during the downsampling process, MAX_VAL and MIN_VAL respectively represent the maximum and minimum values within each group of the original sampling data; PRE_VAL represents the previous new sampling data. For example, when the new sampling point to be obtained is Y2, the value of PRE_VAL is Y1, and when the new sampling point to be obtained is Y3, the value of PRE_VAL is Y2, and so on; TREND_FLAG represents the trend of the new sampling data, which is judged by obtaining two consecutive new sampling data. For example, the two consecutive new sampling data obtained are Y2 and Y3. If Y2 is less than Y3, then TREND_FLAG is equal to 1, indicating an upward trend, otherwise TREND_FLAG is equal to 0, indicating a downward trend. During the downsampling process, TREND_FLAG is continuously updated by the obtained new sampling point data; Y_CUR represents the new sampling data obtained by downsampling the original sampling data group.

[0053] As Figure 3 shown, the steps of selecting the new sampling data for each group of the original sampling data according to the data trend include:

[0054] S31. For the first group of original sampled data, both TREND_FLAG and PRE_VAL are invalid values. The method of obtaining the maximum and minimum data and their positions within the group is used for data selection, and TREND_FLAG and PRE_VAL are initialized as follows:

[0055] First, obtain the maximum data and its position within the group, denoted as MAX_VAL and MAX_POS respectively, and the minimum data and its position, denoted as MIN_VAL and MIN_POS respectively. Next, compare the magnitudes of MAX_POS and MIN_POS. If MAX_POS is greater than MIN_POS, it indicates that the data trend within the group is upward. The new sampled data Y_CUR is MAX_VAL, update the trend of the new sampled data TREND_FLAG to 1 and the previous point's new sampled data PRE_VAL to MAX_VAL. Otherwise, it indicates that the trend is downward. The new sampled data Y_CUR is MIN_VAL, update TREND_FLAG to 0 and PRE_VAL to MIN_VAL.

[0056] S32. After the initialization of TREND_FLAG and PRE_VAL is completed, the original sampled data groups starting from the second group are decimated according to Figure 3 the following logical process:

[0057] After obtaining the original sampled data group, first obtain the maximum value MAX_VAL and the minimum value MIN_VAL within the group, and then compare MIN_VAL and PRE_VAL. If MIN_VAL is greater than or equal to PRE_VAL, it indicates that the overall data trend is upward, and the new sampled data Y_CUR is MAX_VAL. If MIN_VAL is less than PRE_VAL, then continue to compare MAX_VAL and PRE_VAL. If MAX_VAL is less than or equal to PRE_VAL, it indicates that the overall data trend is downward, and the new sampled data Y_CUR is MIN_VAL. If MAX_VAL is greater than PRE_VAL, continue to judge through TREND_FLAG;

[0058] S33. If TREND_FLAG is equal to 1, it indicates that the data trend is upward, and the new sampled data Y_CUR is MAX_VAL; otherwise, Y_CUR is MIN_VAL. If TREND_FLAG is equal to 0, it indicates that the data trend is downward, and the new sampled data Y_CUR is MIN_VAL.

[0059] S34. After the selection of the new sampled data Y_CUR is completed, update TREND_FLAG and PRE_VAL. First, update TREND_FLAG by comparing Y_CUR and PRE_VAL. If Y_CUR is greater than PRE_VAL, indicating an upward trend, set TREND_FLAG to 1; if Y_CUR is less than PRE_VAL, indicating a downward trend, set TREND_FLAG to 0; if Y_CUR is equal to PRE_VAL, keep TREND_FLAG unchanged. Then, complete the update of PRE_VAL by assigning the value of Y_CUR to PRE_VAL. The update order of TREND_FLAG and PRE_VAL needs to be in the order of TREND_FLAG first and then PRE_VAL.

[0060] S35. For each subsequent group of original sampled data, repeat the process of S32 - S34 for data selection to complete the downsampling process of the entire original sampled data.

[0061] In the data selection process of downsampling in the present invention, after grouping the original sampled data according to the downsampling factor, the following judgments and selections are made based on the previous point data trend, the previous point sampling value, and the maximum and minimum values within the group:

[0062] 1) If the minimum value within the current group is greater than or equal to the previous point sampling value, select the maximum value for the current sampling value, and set the current data trend to upward;

[0063] 2) If the maximum value within the current group is less than or equal to the previous point sampling value, select the minimum value for the current sampling value, and set the current data trend to downward;

[0064] 3) If the maximum value within the current group is greater than the previous point sampling value and the minimum value within the current group is less than the previous point sampling value, then judge through the previous point data trend; if the previous point data trend is upward, select the maximum value for the current sampling value, and set the current data trend to upward; if the previous point data trend is downward, select the minimum value for the current sampling value, and set the current data trend to downward;

[0065] Through this kind of judgment and selection, it is ensured that the high-frequency information in the original sampled data is retained during the downsampling process, effectively avoiding the problem of high-frequency signal attenuation in the data after downsampling.

[0066] Based on a similar inventive concept, an embodiment of the present invention further provides a computer storage medium storing a readable program, which can execute the above-mentioned downsampling method for electrocardiogram data when the program runs.

[0067] Based on a similar inventive concept, an embodiment of the present invention provides an electronic device, including: a processor, a memory, a communication interface, and a communication bus, and the processor, the memory, and the communication interface complete communication with each other through the communication bus;

[0068] The memory is used to store at least one executable instruction, and the executable instruction causes the processor to perform the operations corresponding to the above-mentioned downsampling method for electrocardiogram data.

[0069] Based on a similar inventive concept, an embodiment of the present invention further provides a computer program product, including computer instructions, and the computer instructions direct a computing device to perform the operations corresponding to the above-mentioned downsampling method for electrocardiogram data.

[0070] Embodiment 2

[0071] Based on the downsampling method for electrocardiogram data proposed in Embodiment 1, in this embodiment, a downsampling system for electrocardiogram data is proposed, specifically including:

[0072] Downsampling factor calculation module: calculates a downsampling factor according to the original sampling rate and the new sampling rate;

[0073] Original sampled data grouping module: groups the original sampled data of the electrocardiogram according to the downsampling factor, and the number of data points in each group is equal to the value of the downsampling factor;

[0074] And a downsampling module: for each group of original sampled data obtained, selects the maximum or minimum value within the group according to the data trend as the new sampled data to achieve downsampling.

[0075] The method of the present invention can be implemented in hardware, firmware, or be implemented as software or computer code that can be stored in a recording medium (such as a CDROM, RAM, floppy disk, hard disk, or magneto-optical disk), or be implemented as computer code originally stored in a remote recording medium or a non-transitory machine-readable medium and downloaded through a network and to be stored in a local recording medium, so that the method described herein can be stored in such software processing on a recording medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware (such as an ASIC or FPGA). It can be understood that a computer, a processor, a microprocessor controller, or programmable hardware includes a storage component (such as RAM, ROM, flash memory, etc.) that can store or receive software or computer code, and when the software or computer code is accessed and executed by the computer, the processor, or the hardware, the methods described herein are implemented. In addition, when a general-purpose computer accesses the code for implementing the method shown herein, the execution of the code converts the general-purpose computer into a dedicated computer for executing the method shown herein.

[0076] The foregoing has shown and described the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments, and what is described in the above embodiments and the specification is only to illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements fall within the scope of the present invention claimed.

Claims

1. A downsampling method for electrocardiogram data, characterized in that, It includes the following steps: Calculate the downsampling factor according to the original sampling rate and the new sampling rate; Group the original sampling data of the electrocardiogram according to the downsampling factor; For each group of the obtained original sampling data, select the maximum or minimum value within the group according to the data trend as the new sampling data to achieve downsampling.

2. The downsampling method for electrocardiogram data according to claim 1, wherein The calculation formula of the downsampling factor is: Among them, the downsampling factor indicates how many original sampling points are skipped before retaining one new sampling point.

3. The downsampling method for electrocardiogram data according to claim 1, characterized in that After grouping the original sampling data, the number of data points in each group of the original sampling data is equal to the value of the downsampling factor.

4. A downsampling method for electrocardiogram data according to claim 1, wherein, During the downsampling process, the trend of the new sampling data is represented as TREND_FLAG. It is judged by obtaining two consecutive new sampling data. If the previous new sampling data is less than the next new sampling data, then TREND_FLAG is equal to 1, indicating an upward trend. Otherwise, TREND_FLAG is equal to 0, indicating a downward trend. During the downsampling process, TREND_FLAG is continuously updated through the obtained new sampling data.

5. A downsampling method for electrocardiogram data according to claim 4, characterized in that, The steps of selecting new sampling data for each group of the original sampling data according to the data trend include: S31. For the first group of the original sampling data, first obtain the maximum data MAX_VAL and its position MAX_POS, and the minimum data MIN_VAL and its position MIN_POS within the group; then compare the sizes of MAX_POS and MIN_POS; if MAX_POS is greater than MIN_POS, it means the data trend within the group is upward, the new sampling data Y_CUR is MAX_VAL, update the trend TREND_FLAG of the new sampling data to 1 and the previous-point new sampling data PRE_VAL to MAX_VAL; otherwise, it means the trend is downward, the new sampling data Y_CUR is MIN_VAL, update TREND_FLAG to 0 and PRE_VAL to MIN_VAL; S32. For the second group of the original sampling data, first obtain the maximum value MAX_VAL and the minimum value MIN_VAL within the group, and then compare MIN_VAL and PRE_VAL; if MIN_VAL is greater than or equal to PRE_VAL, it means the overall data trend of the group is upward, the new sampling data Y_CUR is MAX_VAL; if MIN_VAL is less than PRE_VAL, then continue to compare MAX_VAL and PRE_VAL; if MAX_VAL is less than or equal to PRE_VAL, it means the overall data trend of the group is downward, the new sampling data Y_CUR is MIN_VAL; if MAX_VAL is greater than PRE_VAL, continue to judge through TREND_FLAG; S33. If TREND_FLAG is equal to 1, it means the data trend is upward, the new sampling data Y_CUR is MAX_VAL, otherwise Y_CUR is MIN_VAL; if TREND_FLAG is equal to 0, it means the data trend is downward, the new sampling data Y_CUR is MIN_VAL; After the selection of the new sampled data Y_CUR is completed, TREND_FLAG and PRE_VAL are updated. First, TREND_FLAG is updated by comparing Y_CUR and PRE_VAL. If Y_CUR is greater than PRE_VAL, indicating an upward trend, TREND_FLAG is set to 1. If Y_CUR is less than PRE_VAL, indicating a downward trend, TREND_FLAG is set to 0. If Y_CUR is equal to PRE_VAL, TREND_FLAG remains unchanged. Then, PRE_VAL is updated by assigning the value of Y_CUR to PRE_VAL. The update order of TREND_FLAG and PRE_VAL must be in the order of TREND_FLAG first and then PRE_VAL. S35. For each subsequent group of original sampled data, S32 - S34 are repeated for data selection to complete the downsampling process of the entire original sampled data.

6. The downsampling method for electrocardiogram data according to claim 5, wherein After grouping the original sampled data according to the downsampling factor, the following judgments and selections are made based on the previous point data trend, the previous point sampled value, and the maximum and minimum values within the group: 1) If the minimum value within the current group is greater than or equal to the previous point sampled value, the current sampled value selects the maximum value, and the current data trend is set to upward. 2) If the maximum value within the current group is less than or equal to the previous point sampled value, the current sampled value selects the minimum value, and the current data trend is set to downward. 3) If the maximum value within the current group is greater than the previous point sampled value and the minimum value within the current group is less than the previous point sampled value, then it is judged by the previous point data trend. If the previous point data trend is upward, the current sampled value selects the maximum value, and the current data trend is set to upward. If the previous point data trend is downward, the current sampled value selects the minimum value, and the current data trend is set to downward.

7. A downsampling system for electrocardiogram data, characterized in that, Including: Downsampling factor calculation module: Calculate the downsampling factor according to the original sampling rate and the new sampling rate. Original sampled data grouping module: Group the original sampled data of the electrocardiogram according to the downsampling factor. And a downsampling module: For each group of original sampled data obtained, select the maximum or minimum value within the group according to the data trend as the new sampled data to achieve downsampling.

8. A computer storage medium stores a readable program, characterized in that, When the program runs, it can execute a downsampling method for electrocardiogram data according to any one of claims 1 - 6.

9. An electronic device, characterized in that, Including: A processor, a memory, a communication interface, and a communication bus. The processor, the memory, and the communication interface complete communication with each other through the communication bus. The memory is used to store at least one executable instruction, and the executable instruction causes the processor to execute the operations corresponding to a downsampling method for electrocardiogram data according to any one of claims 1 - 6.

10. A computer program product comprising computer instructions, characterized in that, The computer instruction instructs the computing device to execute the operations corresponding to a downsampling method for electrocardiogram data according to any one of claims 1 - 6.

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