Portable multi-lead electrocardiogram monitoring system and electrocardiogram recorder

Abstract

The invention relates to the technical field of electrocardio monitoring, in particular to a portable multi-lead electrocardio monitoring system and an electrocardio recorder, and the portable multi-lead electrocardio monitoring system comprises an electrocardio data acquisition module which is electrically connected to a plurality of lead electrode slices to acquire electrocardio signals and perform digital-to-analog conversion processing on the electrocardio signals; the motion data acquisition module is used for acquiring motion signals; the data processing module is electrically connected to the electrocardio data acquisition module and the motion data acquisition module and is used for acquiring and processing the acquired electrocardio signals and the motion signals; the data storage module is electrically connected to the data processing module and is used for acquiring and regionally writing the processed electrocardiosignals and motion signals for storage; and the data transmission module is used for enabling the data processing module to be in wired and / or wireless connection with external equipment so as to realize bidirectional data transmission. The portable electrocardiogram recording device has the advantage that the electrocardiogram data can be comprehensively monitored and recorded through the portable electrocardiogram recording device.

Description

Technical Field

[0001] The present application relates to the technical field of electrocardiogram (ECG) monitoring, and in particular to a portable multi-lead ECG monitoring system and an ECG recorder. Background Art

[0002] When providing medical care and daily monitoring for heart disease patients, continuous monitoring of their ECG data is necessary. Hospital ECG recorders are connected to patients via multiple electrodes, which monitor the patient's heart's electrical impulses and analyze the signals to obtain the patient's ECG data.

[0003] The standard 12-lead ECG device in clinical practice requires patients to lie flat on the bed for a long time when measuring ECG data. On the one hand, this affects the patient's normal physiological activities. On the other hand, due to the large size and high cost of the device, patients cannot effectively use it in daily situations such as at home or when going out.

[0004] Currently, most portable ECG recorders use a single-lead or three-lead mode. Although they can be portable and attached to patients for daily monitoring without restricting normal behavioral activities, due to the small size of the portable device, only partial monitoring data can be obtained. Signal monitoring is unstable and incomplete, and it cannot accurately and comprehensively reflect the twelve-lead ECG. Summary of the Invention

[0005] In order to achieve comprehensive monitoring and recording of ECG data through portable ECG recording equipment, the present application provides a portable multi-lead ECG monitoring system and an ECG recorder.

[0006] In a first aspect, the present application provides a portable multi-lead ECG monitoring system, which adopts the following technical solutions: A portable multi-lead electrocardiogram monitoring system comprising: An ECG data acquisition module, electrically connected to a plurality of lead electrodes to collect ECG signals and perform digital-to-analog conversion on the ECG signals; A motion data acquisition module, configured to acquire motion signals, wherein the motion signals include at least acceleration and posture; a data processing module, electrically connected to the ECG data acquisition module and the motion data acquisition module, for acquiring the acquired ECG signals and motion signals to perform processing including but not limited to feature extraction, data filtering, data compression, and interrupt optimization; A data storage module, electrically connected to the data processing module, for acquiring and writing the processed electrocardiogram signal and motion signal into different regions for storage; The data transmission module is used to connect the data processing module to an external device via wired and / or wireless communication to achieve bidirectional data transmission.

[0007] In some embodiments, the data processing module includes a feature extraction unit, a data filtering unit, and a pre-built-in DSP instruction set, specifically: The data filtering unit calls a signed multiplication-accumulation instruction in the DPS instruction set to calculate a channel filter value for the channel in each register; The feature extraction unit calls the differential threshold method in the DPS instruction set to calculate the difference between the original sampling values ​​of adjacent sampling points, and determines the starting point of the QRS wave based on the number of times the difference between the original sampling values ​​is greater than a preset value; The feature extraction unit calls the multiplication and accumulation instruction in the DPS instruction set to calculate the sliding window mean of the RR interval corresponding to each of the original sampling value differences; The feature extraction unit calls a divider instruction in the DPS instruction set and calculates a heart rate value based on a sliding window mean of the RR interval.

[0008] In some embodiments, the data processing module includes a data compression unit configured to: Obtaining original sampling values ​​corresponding to each channel, wherein the channel corresponds to the electrocardiogram signal and the motion signal; Calculating a first difference between the current raw sampling value and the previous raw sampling value to generate an electrocardiogram data stream and a motion data stream; Obtaining timestamps corresponding to the electrocardiogram data stream and the motion data stream for data organization, and obtaining a write frame of fixed byte length after the data organization to achieve single-channel data compression, wherein the write frame includes at least a timestamp, data stream content, a packet sequence number, a check code, and a first compression tag; Based on the first difference, the corresponding quantization step size is dynamically matched in a preset step size table, and the corresponding index adjustment rule is associated.

[0009] In some embodiments, the data processing module includes a data compression unit, which is further configured to: Obtaining the channel stability corresponding to each of the ECG signals and each of the motion signals, and using the channel with the highest stability as the ECG reference channel and the motion reference channel, respectively; Calculate second differences between the original sampling values ​​in the other channels and the ECG reference channel and the motion reference channel based on the timestamp to generate an ECG inter-channel data stream and a motion inter-channel data stream; The timestamps corresponding to the data streams between the ECG channels and the data streams between the motion channels are obtained for data organization. After the data organization, a write frame with a fixed byte length is obtained to achieve inter-channel data compression. The write frame includes at least a timestamp, data stream content, a packet sequence number, a check code, and a second compression tag.

[0010] In some embodiments, the data transmission module includes a wired transmission module and a wireless communication module, wherein: The data processing module determines whether the level of the charging IO port is high. If so, it controls the analog switch to open a path between the data storage module and the data processing module, and mounts the data processing module as a USB flash drive to read the electrocardiogram signal and the motion signal through the wired transmission module; The wireless communication module is connected to the external device via Bluetooth for wireless transmission. The wireless communication module is used to transmit the electrocardiogram signal, the motion signal and / or device information to the external device, and is also used to obtain the correction time and software package issued by the external device.

[0011] In some embodiments, the data processing module further includes an interruption optimization unit, specifically configured to: Predefine an interrupt priority rule, wherein the interrupt priority rule includes a priority matching item and a priority raising item; Obtaining event information triggered by each module and identifying the interrupt source corresponding to the event information; Matching the interrupt source in the priority matching items to obtain a corresponding first priority; Obtaining simultaneously triggered combined event information, and determining whether the combined event information completely matches the priority boosting item; if so, configuring a corresponding second priority for the combined event information, wherein the second priority is greater than the first priority of each independent event information in the combined event information; Determine whether the priority of the currently triggered interrupt source is greater than the priority of the current interrupt source; If it is greater, the current interrupt source is interrupted and forced to be suspended and matched to the processing action corresponding to the currently triggered interrupt source for execution, and the processing action corresponding to the suspended interrupt source is resumed after the processing action is completed.

[0012] In some embodiments, the first priority of the interrupt source corresponding to each of the event information constituting the combined event information is lower than the preset priority.

[0013] In some embodiments, the interruption optimization unit is further configured to: Obtaining the timestamp corresponding to each event information; If the timestamps are all within a preset time range and the event information corresponds to the same interrupt source or the same processing action, the event information is interrupt-merged and matched with the processing action once for parallel processing.

[0014] In some embodiments, the interruption optimization module is further configured to: Determining whether the interrupt source is the electrocardiogram data acquisition module or the motion data acquisition module; If yes, obtaining the current timestamp based on the event information; When the interrupt source is the electrocardiogram data acquisition module, marking the motion signal at the corresponding time based on the timestamp; When the interrupt source is the motion data acquisition module, the electrocardiogram signal at the corresponding time is marked based on the timestamp.

[0015] In a second aspect, the present application provides an electrocardiogram recorder, which adopts the following technical solution: An electrocardiogram recorder includes a host integrating the above-mentioned portable multi-lead electrocardiogram monitoring system, and also includes a plurality of monitoring patches electrically connected to the host, wherein the monitoring patches at least include an auxiliary neutral electrode, a plurality of simulated limb electrodes and a plurality of chest electrodes.

[0016] The technical solutions provided by the embodiments of this application have the following technical effects: The integrated configuration of a portable small ECG recorder is realized, and the process of low-power, small-volume ECG data collection, processing, analysis, and transmission is achieved from the hardware and embedded levels. The ECG recorder obtained based on this system integration meets the requirements of portability and multi-lead data collection and analysis, and is more stable and comprehensive for ECG monitoring based on a small volume. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of a single-board module of a portable multi-lead ECG monitoring system provided in this embodiment.

[0018] Figure 2 Schematic diagram of the appearance of the electrocardiograph in the embodiment of the present application.

[0019] Figure 3 It is a working schematic diagram of the electrocardiogram recorder in the embodiment of the present application.

[0020] Figure 4 This is a waveform diagram of ECG data recorded by an ECG recorder integrated with a portable multi-lead ECG monitoring system in an embodiment of the present application.

[0021] Explanation of the accompanying drawings: 1. ECG data acquisition module; 2. Motion data acquisition module; 3. Data processing module; 4. Data storage module; 5. Data transmission module. DETAILED DESCRIPTION

[0022] In order to more clearly understand the purpose, technical solutions and advantages of the present application, the present application is described and illustrated below in conjunction with the accompanying drawings and embodiments. However, it should be understood by those skilled in the art that the present application can be implemented without these details. In some cases, in order to avoid unnecessary descriptions that make various aspects of the present application obscure, the well-known methods, processes, systems, components and / or circuits that have been described at a higher level will not be described in detail. It is obvious to those skilled in the art that various changes can be made to the embodiments disclosed in the present application, and the general principles defined in the present application can be applied to other embodiments and application scenarios without departing from the principles and scope of the present application. Therefore, the present application is not limited to the embodiments shown, but conforms to the broadest scope consistent with the scope claimed for protection in the present application.

[0023] It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0024] In the description of this application, "several" means one or more, "many" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, while "above," "below," and "within" are understood to include the number itself. The use of "first" and "second" in the description is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0025] In the description of this application, reference to the terms "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of this application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any combination in one or more embodiments or examples.

[0026] like Figure 1 As shown, the embodiment of the present application discloses a portable multi-lead ECG monitoring system, comprising: The ECG data acquisition module is electrically connected to a plurality of lead electrodes to collect ECG signals and perform digital-to-analog conversion on the ECG signals.

[0027] The ECG data acquisition module includes 10 12-lead patch electrodes and an ECG AFE chip, which forms 8 analog differential inputs. After passing through an RC radio frequency filter, it is connected to the 8 ADCs in the ECG AFE chip to filter out high-frequency radio frequency interference. All acquisition and analog-to-digital conversion are completed inside the AFE chip. The converted data will be stored in their respective corresponding data registers and a notification will be sent to the main control. When data reading is required, the converted digital signal will be subsequently transmitted to the data processing module based on the SPI interface. This cycle is repeated to obtain the ECG data stream.

[0028] The motion data acquisition module is used to collect motion signals, which at least include acceleration and posture.

[0029] In the embodiment of the present application, the motion data acquisition module is a 6-axis motion sensor of model LSM6DSLTR, which includes an acceleration monitoring unit and a gyroscope, which can be used to monitor at least acceleration data and 6-axis posture trends, and is mainly used to monitor whether the user falls, exercises, etc.

[0030] Similarly, the collected motion signal is also modified by the main control of the configuration register of the motion data acquisition module so that it completes the analog-to-digital conversion of the motion signal according to a fixed sampling rate, and stores the converted motion data in their respective registers, and sends a notification to the main control. When data reading is required, the converted digital signal will be subsequently transmitted to the data processing module based on the SPI interface, and the data stream of motion data is obtained in this cycle.

[0031] The data processing module is electrically connected to the ECG data acquisition module and the motion data acquisition module, and is used to obtain the collected ECG signals and motion signals for processing including but not limited to feature extraction, data filtering, data compression, and interrupt optimization.

[0032] In the embodiment of the present application, the data processing module is a wireless control chip nRF52832 with Bluetooth transmission function, which is mainly used to process the collected ECG signals and motion signals. The data processing includes at least signal feature extraction, data filtering, data compression, and optimization processing of data interruption conflicts.

[0033] The data processing part is mainly performed by the application software running in the Cortex-M4 core of the nRF52832, which can collect 250 analog voltages per second and write them into the subsequent data storage module via SPI.

[0034] Compared with the traditional CC26240 chip, nRF52832 has more IO ports for connecting to peripherals, and is smaller in size and consumes less power.

[0035] The data storage module is electrically connected to the data processing module and is used to acquire and write the processed electrocardiogram signals and motion signals into different regions for storage.

[0036] The data storage module is connected to the nRF52832 and uses SD NAND flash. The flash capacity is 4GB. It controls its own power on and off through PMOS to reduce the standby power consumption of the device.

[0037] When working normally, the control chip nRF52832 operates the flash, and when the external device reads data, the flash needs to be accessed by the external device through the corresponding SD controller.

[0038] Therefore, it is necessary to switch the data bus of the data storage module. In the embodiment of the present application, two 2-way USB switches are used to control the switching.

[0039] When working, the data storage module obtains the processed ECG and motion signals and writes them into the SD NAND flash. The control chip nRF52832 is connected to the flash through an analog switch. When the system enters the working mode, the control chip controls the analog switch to open the path between the flash and the data, and then writes the data into the flash in the form of a file. The file system uses FATFS.

[0040] The stored ECG data stream and motion data stream will be written into two different files for separate storage. When reading this part of the data later, you can read only the ECG data, only the motion data, or both together based on the synchronized timestamp.

[0041] The data transmission module is used to connect the data processing module to external devices via wired and / or wireless communication to achieve two-way data transmission.

[0042] The data transmission module is used to transmit ECG signals and / or motion signals to external devices based on wired or wireless means when data needs to be acquired. The wired means in this application is a USB-based wired transmission connection, and the wireless means in this application is a Bluetooth communication connection.

[0043] The wired type-c external interface configured in this application can be used to read the data stored in the internal flash.

[0044] In this application, the wireless module is a Bluetooth module configured by the nRF52832 chip, and its radio frequency is a single-ended output.

[0045] like Figure 4 As shown, through the above steps, the integrated configuration of a portable small ECG recorder is realized, and the process of low-power, small-volume ECG data acquisition, processing, analysis, and transmission is realized from the hardware and embedded levels. The ECG recorder obtained based on this system integration meets the requirements of portability and multi-lead data acquisition and analysis, and is more stable and comprehensive for ECG monitoring based on a small volume.

[0046] In other embodiments, it further includes a power module, a download interface, and an indicator light, wherein: The power module includes a lithium battery and the nRF52832 chip's built-in DCDC. The lithium battery's output voltage is regulated by the DCDC, which then powers the nRF52832 main chip and other modules. The ECG acquisition module is powered by an IO port on the nRF52832 chip and can be completely shut down during standby mode to reduce power consumption.

[0047] The download interface is the SWD interface, which has 6 test points: GND, RESETn, SWDIO, SWDCLK, VCC, and SW0.

[0048] RESETn is the reset pin used to wake up the main chip MCU and enter low-power mode. SW0 is the serial output pin used to transmit debug trace signals. Together with the read and write functions of SWDIO and SWDCLK, it forms a complete debug link.

[0049] At the same time, indicator lights are set on the system board. In this application, there are one blue LED and one orange LED to indicate the status of the device when it is in use.

[0050] In other embodiments, an RTC module and a log module are also included.

[0051] The RTC module is a timing unit independent of the main control and is powered directly by the battery. The main control communicates with the RTC module through the IIC interface and can read and modify internally recorded events. When the host and mobile device are in Bluetooth connection, the host can obtain events from the mobile device to correct events within the RTC module. The main control monitors the battery capacity and forces it into a low-power state when the battery capacity is too low. The remaining battery power can ensure that the RTC module works for 100 days.

[0052] The RTC module in this embodiment of the application uses the extremely low-power EPSON REX8111.

[0053] The log module records various states of the host during operation. The implementation method is that the main control writes the log information to the flash in the form of a file. The process is the same as the method of writing the ECG data stream and motion data stream. By partitioning different file names, the required information is obtained by reading the log file in the transmission mode.

[0054] In other embodiments, the data processing module includes a feature extraction unit, a data filtering unit, and a pre-built-in DSP instruction set. The DSP instruction set is a set of several DSP instructions configured using the Cortex-M4 core built into the nRF52832. Each DPS instruction is matched to an arithmetic device on the nRF52832. Specifically: The data filtering unit calls the signed multiplication and accumulation instruction in the DPS instruction set to calculate the channel filter value for the channel in each register.

[0055] For ECG data, the most important feature is the feature extraction of the QRS wave, P wave, and T wave of the ECG signal. Traditional ECG instruments use software algorithms to calculate the features of each wave, which is time-consuming. However, this application uses the embedded assembly of application software in the hardware to achieve rapid internal feature extraction after ECG data acquisition. The feature extraction work is based on the unique structure and function of the hardware. It fully utilizes the hardware computing resources of the main control chip, breaks through the computing power limitations of the embedded platform through instruction-level optimization, and realizes the "real-time acquisition-feature extraction-transmission" pipeline processing.

[0056] First, data is received, cached and filtered. When receiving the buffer, the 8-channel digital ECG signals output by the AFE chip are received through the SPI interface and buffered in the register buffer SRAM of the nRF52832.

[0057] Configure the nRF52832's SPI peripheral to "interrupt mode" and trigger an SPI interrupt when the AFE948 data is ready (DRDY pin level jumps); In the interrupt service routine, 8 channels of data are read in batches through the hardware SPI controller's FIFO (8 × 24 bits = 24 bytes each time) and stored in the SRAM's ring buffer (size 250 × 24 bytes, which can cache 1 second of data) to avoid data overflow.

[0058] During filtering, the original data is filtered (50 Hz power frequency interference suppression and baseline drift removal) to reduce the impact of noise on feature extraction.

[0059] A second-order IIR filter is used, and its differential equation is y[n]=2*cos(2π*50 / fs)*y[n-1]-y[n-2]+x[n]-2*cos(2π*50 / fs)*x[n-1] + x[n-2] (fs=250Hz).

[0060] x[n] represents the input signal, that is, the original acquired signal, which corresponds to the unprocessed ECG signal (digital quantity after analog-to-digital conversion) and the original motion signal acquired by the 6-axis sensor.

[0061] y[n] represents the output signal, that is, the signal after filtering.

[0062] n represents the sampling point index (timing mark) of the current moment, n-1 represents the "previous sampling point", and n-2 represents the "previous two sampling points".

[0063] 2π*50 is the angular frequency of 50 Hz. Dividing it by the sampling rate fs gives the normalized angular frequency. The cosine value is used to determine the pole / zero locations of the filter to ensure maximum attenuation of the 50 Hz signal.

[0064] Among them, DSP can accelerate the filtering process based on multi-channel filtering. In traditional filtering, the 8-channel signal is processed in a loop according to "input-coefficient multiplication-accumulation-output" based on software. Single-channel filtering requires 32 operations. However, this application can call the signed multiplication and accumulation in the DSP instruction set to complete (register 1*register 2) + register 3→register 4) within 1 clock cycle, supporting parallel processing of multiplication and accumulation of 4 signals, thereby compressing multi-channel data filtering.

[0065] The feature extraction unit calls the differential threshold method in the DPS instruction set to calculate the difference between the original sampling values ​​of adjacent sampling points, and determines the starting point of the QRS wave based on the number of times the original sampling value difference is greater than a preset value.

[0066] The DPS instruction set uses the differential threshold method to calculate the difference between adjacent sampling points: diff[n] = |x[n] - x[n - 1]|. If the difference between the original sample values, diff[n], exceeds a preset dynamic threshold three times in a row, the QPS wave is considered to have started. In this embodiment, the dynamic threshold is 60% of the maximum value in the previous 5 seconds.

[0067] The feature extraction unit calls the multiplication and accumulation instruction in the DPS instruction set to calculate the sliding window mean of the RR interval corresponding to the difference between each original sampling value.

[0068] The MAC (multiplication-accumulation) instruction is used to batch calculate the sliding window mean of the absolute values ​​of each differential value calculated by the above differential threshold method, replacing the traditional loop accumulation, so as to improve the calculation efficiency.

[0069] The sliding window mean can calculate the average value of continuous sampling points, smooth the high-frequency signals in the signal, improve data quality, and obtain the time interval between the two R wave peaks in each QRS wave to define it as the RR interval.

[0070] The feature extraction unit calls the divider instruction in the DPS instruction set and calculates the heart rate value based on the sliding window mean of the RR interval.

[0071] After the accurate and smooth RR interval is calculated, the heart rate value is calculated based on the RR interval by calling the divider instruction in the DPS instruction set.

[0072] In traditional solutions, it is implemented through a software division function, and a single calculation takes a long time.

[0073] In this embodiment, an unsigned divide instruction is first retrieved from the DPS instruction set, and the Cortex-M4's hardware divider is invoked. The RR interval (in milliseconds) is stored in register a, and 60,000 is stored in register b. The divide instruction is then executed to directly perform a division calculation in register c, converting it to a heart rate value (beats / minute). Specifically, heart rate = 60,000 / RR interval. All of this is performed in hardware, replacing software division operations with hardware-implemented divide instructions, reducing the overall data analysis and computation time.

[0074] In some other embodiments, the data processing module includes a data compression unit, which is configured to: Obtain the original sampling value corresponding to each channel, where the channel corresponds to the electrocardiogram signal and the motion signal.

[0075] When collecting ECG data and motion data, they are divided into several channels to achieve differential input. In order to reduce subsequent transmission time and storage space, this application also requires compressing the ECG data stream and motion data stream in each channel.

[0076] In this application, the data compression in each channel adopts the ADPCM adaptive differential pulse code modulation method.

[0077] Both ECG data and motion data have waveform continuity, so the difference between adjacent sampling values ​​is small, so the ADPCM compression method is more effective.

[0078] A first difference between a current raw sampling value and a previous raw sampling value is calculated to generate an electrocardiogram data stream and a motion data stream.

[0079] When the original sample value is obtained, the present application does not directly store the original sample value (eg, 16 bits), but instead records the difference between the current sample and the previous sample, and represents the difference with a smaller bit, such as 4 bits.

[0080] The timestamps corresponding to each ECG data stream and motion data stream are obtained for data organization, and after the data organization, a write frame with a fixed byte length is obtained to achieve single-channel data compression.

[0081] Before being written to the flash, the compressed ECG data stream and acceleration data stream are reorganized and converted into fixed byte length as write frames. Each frame contains a timestamp, packet sequence number, checksum, data stream content and the first compression tag.

[0082] Among them, the timestamp represents the time when the data is sampled, the packet number represents the order of data packets used to identify sending and receiving, each frame of data corresponds to a unique packet number, the check code is used to verify the integrity and accuracy of the frame in data communication, and the first compression tag is used to indicate that the frame data is obtained based on the compression method of the data in each channel.

[0083] Based on the first difference, the corresponding quantization step size is dynamically matched in a preset step size table, and the corresponding index adjustment rule is associated.

[0084] The compression ratio is usually 1:4. The quantization step size can be adjusted dynamically based on the difference amplitude. For example, the step size is increased when the difference is large, and the step size is reduced when the difference is small, to ensure that 4 bits can always cover the entire difference range.

[0085] At the same time, adaptive control of quantization accuracy is achieved through predefined index adjustment rules.

[0086] In the above scheme, each channel data is compressed separately without considering the signal correlation between channels, such as the correlation between ECG waveforms of different leads and the synchronization between movement and ECG data. Therefore, the waveform data differences between channels cannot be reflected. Therefore, in some other embodiments, the data processing module includes a data compression unit, which is further configured to: The channel stability corresponding to each ECG signal and each motion signal is obtained, and the channel with the highest stability is used as the ECG reference channel and the motion reference channel, respectively.

[0087] First, the most stable channels are selected as reference channels from among the channels corresponding to the ECG signal and the channels corresponding to the motion signal. For example, if the ECG data of lead II in the ECG signal is stable, then the channel corresponding to this lead can be used as the reference channel. For example, if the data corresponding to the x-axis in the 6-axis is relatively stable, then the channel corresponding to this axis can be used as the reference channel.

[0088] The sampling value corresponding to the reference channel can be used as a reference value.

[0089] Second differences between original sampling values ​​in other channels and the ECG reference channel and the motion reference channel are calculated based on the timestamps to generate an ECG inter-channel data stream and a motion inter-channel data stream.

[0090] Taking ECG data as an example, the sampling values ​​of all ECG channels except the reference channel are subtracted from the sampling value of the reference channel. The dynamic range of the difference is smaller than the original signal. Then, the second difference is compressed based on the ADPCM algorithm.

[0091] It should be noted that when calculating the second difference, it is necessary to ensure that the values ​​calculated for the difference between each channel are at the same timestamp to avoid decompression misalignment due to time offset.

[0092] By compressing the signals between channels, the lead or axis with the most stable signal is used as a reference, and the difference between the overall data of other channels and the overall data of the reference channel is calculated for compression. The compression process directly retains the differential relationship between channels. After decompression, the relative waveform characteristics of multiple channels can be directly restored, such as the offset difference of the ECG ST segment in different leads and the coordinated changes in the three-axis acceleration during exercise, without the need for additional algorithms to reconstruct the channel relationship.

[0093] The timestamps corresponding to the data streams between the ECG channels and the motion channels are obtained for data organization. After the data organization, a write frame with a fixed byte length is obtained to achieve inter-channel data compression. The write frame includes at least a timestamp, data stream content, packet sequence number, check code, and a second compression tag.

[0094] Similar to single-channel data compression, after inter-channel data compression, before being written to the flash, it will be reorganized and converted into a fixed byte length as a write frame. Each frame includes at least a timestamp, data stream content, packet sequence number, checksum and a second compression tag.

[0095] Meanwhile, the second compression tag is used to indicate that the frame data is compressed based on differential calculation of data between channels.

[0096] By decompressing the frame data obtained by different compression methods and different compression objects, the system is reminded of the specific method of data compression through the compression label in the frame data. When the frame data needs to be decompressed during data reading, it is necessary to decompress the frame data based on the matching decompression method. If the written frame with the first compression label is decompressed, the continuous ECG signal or motion signal of each channel at each time is obtained. If the written frame with the second compression label is decompressed, the relative waveform feature relationship on the corresponding timestamps between the channels, the coordinated results of the motion data, the waveform deviation of different leads at the same time and other combined information are obtained.

[0097] In some other embodiments, the data transmission module includes a wired transmission module and a wireless communication module, wherein: The data processing module determines whether the level of the charging IO port is high. If so, it controls the analog switch to open the path between the data storage module and mounts the data processing module as a USB flash drive to read the ECG signal and motion signal through the wired transmission module.

[0098] The wired transmission module transmits the ECG data and motion data stored in the host flash to the computer. When the host is connected to the computer via a USB cable, the main control detects that the charging IO port level is high and enters the wired transmission mode. In the transmission mode, the main control analog switch opens the path between the card reader IC and the flash. The computer will mount the flash in the host as a USB disk and directly read the ECG data files and motion data files in the USB disk to obtain the corresponding data.

[0099] The wireless communication module establishes a Bluetooth connection with an external device for wireless transmission. The wireless communication module is used to transmit electrocardiogram signals, motion signals and / or device information to the external device, and is also used to obtain the correction time and software package issued by the external device.

[0100] The Bluetooth communication module enables wireless data transmission. Other devices, such as mobile phones, computers, and watches, can use Bluetooth to obtain information such as the host's battery life, memory capacity, ECG data, and exercise data, and can also modify the host's configuration. The host can also use Bluetooth to obtain calibration time and software packages for program upgrades.

[0101] In some other embodiments, the data processing module further includes an interruption optimization unit, specifically configured to: An interrupt is a real-time notification sent by a hardware module to the MCU chip. It is generated when the device needs to respond to dynamically changing external or internal states.

[0102] For example, every time the AFE ECG chip completes sampling of ECG data, it must immediately notify the host to read the data, otherwise it will cause FIFO overflow and data loss; if the six-axis sensor detects that the user has fallen, an alarm must be triggered.

[0103] The change of the sub-state and the triggering of the action behavior correspond to an interrupt.

[0104] At the same time, different interrupts correspond to different times and require differentiated processing solutions. If the system does not recognize the interrupt, the main control chip cannot distinguish whether it is "AFE data ready (signal needs to be read)" or "fall detection (alarm needs to be triggered)", which will cause confusion in the processing logic.

[0105] Different hardware modules correspond to different interrupt sources. Only by accurately identifying the specific objects of the interrupt sources and the priorities of different interrupt sources can the correct processing logic be issued for the interrupts that need to be handled more urgently, avoiding conflicts caused by multiple interrupts in a short period of time.

[0106] Predefined interrupt priority rules, which include priority matching items and priority improvement items.

[0107] First, obtain the predefined interrupt priority rules to configure appropriate priorities for subsequent different interrupt sources.

[0108] Among them, the interrupt priority includes priority matching items and priority improvement items. The priority matching item represents the basic priority configured for an interrupt source, and the priority improvement item represents the configuration item corresponding to the priority improvement of special interrupts or combined interrupts.

[0109] Match the interrupt source in the priority matching items to obtain the corresponding first priority.

[0110] Obtain the event information triggered by each module and identify the interrupt source corresponding to the event information.

[0111] Different interrupt sources have different basic priorities, such as: Highest priority: Sudden interruption of electrode contact impedance requires power wake-up, and the response time is less than 1ms.

[0112] High priority: AFE ECG data ready interrupt, which needs to promptly inform the host to read data to avoid FIFO overflow.

[0113] Medium priority: The six-axis sensor fall detection is interrupted and an alarm is required.

[0114] Low priority: RTC clock module timing interrupt.

[0115] Then, the interrupt source corresponding to the triggered event can match the corresponding priority information in the interrupt priority rule.

[0116] If the electrode impedance is interrupted, the contact impedance of electrodes V4 and V6 in the 10 electrodes drops below the threshold. The hardware comparator outputs a high level, which is connected to the nRF52832's PPI (Programmable Peripheral Interconnect) module, directly triggering the DCDC enable signal and notifying the main control chip by generating an interrupt. (When in standby mode, the switch chip connects electrodes V4 and V6 to the pull-up resistor and GND, respectively, leaving them floating. The voltage divider resistor in the circuit turns on the MOSFET, grounding the power supply enable pin and shutting down the power supply. When the electrodes are connected to the human body, the resistor in the circuit forms a voltage divider in parallel with the human body resistance. This voltage divider is much lower than the voltage when there is no human contact, so the MOSFET cannot turn on, causing the power supply enable pin to be pulled high, and the power supply begins to supply power.)

[0117] When the AFE ECG data is ready for interruption, its DRDY pin outputs a low-level pulse after each frame of data conversion is completed, triggering the interruption; When the six-axis sensor is interrupted, its INT1 pin outputs a high level when it detects fall characteristics (acceleration greater than 8g and angular velocity greater than 1000 / s), triggering an external interrupt.

[0118] When the RTC clock is interrupted, the INT pin of the clock outputs an interrupt every 1 second to update the system timestamp.

[0119] Different priorities are matched to each triggered event based on the identification of the interrupt source. When an interrupt conflict occurs later, the priority is used to determine which interrupts need to be processed first to avoid low-priority interrupts blocking high-priority events.

[0120] Acquire the combined event information that is triggered simultaneously, and determine whether the combined event information completely matches the priority improvement item. If so, configure the corresponding second priority for the combined event information.

[0121] Some events are combined from responses of multiple hardware components. For example, when a user falls and the electrode pads fall off, it will simultaneously trigger abnormal interruptions of the six-axis sensor and the AFE ECG data. At this time, there is a correlation between multiple interrupts. When the combined event information of the correlation matches the priority increase item, the second priority corresponding to the combined event information needs to be dynamically adjusted, because the event composed of multiple interrupts should have a higher processing priority than a single event.

[0122] At the same time, the interrupt priority corresponding to the combined event needs to be higher than the priority corresponding to each individual event interrupt source in the combined event.

[0123] For example, if the six-axis sensor interrupt corresponds to priority 3 and the AFE ECG data abnormal interrupt corresponds to priority 2, then the priority corresponding to the combined event that triggers the six-axis sensor interrupt and the AFE ECG data abnormal interrupt is at least priority 1, which is higher than priority 2 and priority 3.

[0124] Determine whether the priority of the currently triggered interrupt source is greater than the priority of the current interrupt source.

[0125] If it is greater, the current interrupt source will be interrupted and forced to suspend and match the processing action corresponding to the currently triggered interrupt source to proceed, and the processing action corresponding to the suspended interrupt source will be resumed after the processing action is completed.

[0126] In the embodiment of the present application, an interrupt nesting mechanism is adopted. When a high-priority interrupt occurs and a low-priority interrupt is currently being processed, the high-priority interrupt is allowed to preempt the interrupt service of the low-priority interrupt. For example, the electrode impedance interrupt (priority 2) can interrupt the RTC interrupt (priority 4) that is being executed.

[0127] It should be noted that when a high-priority interrupt preempts the interrupt service of a low-priority interrupt, the low-priority interrupt will record the context in the interrupt service routine (ISR) and suspend it. When the high-priority interrupt is processed, the suspended low-priority interrupt will be resumed and the unfinished processing action will be resumed based on the context information.

[0128] In some other embodiments, the interrupt optimization unit is further configured to: Get the timestamp corresponding to each event information.

[0129] When event information occurs, the corresponding timestamp information when the event occurs is obtained in the RTC module through the corresponding interrupt source.

[0130] If the timestamps are all within the preset time range and the event information corresponds to the same interrupt source or the same processing action, the event information is interrupt-merged and matched with a processing action to be sent for parallel processing.

[0131] When the timestamp shows that a device has multiple interrupts of the same type or multiple modules have parallel interrupts but the processing actions are the same within a short period of time, such as receiving more than 3 RTC timer interrupt information within 100ms, the interrupt optimization unit will automatically merge several interrupts of the same type or with the same processing actions into one for processing.

[0132] This can reduce the computing load of the MCU, because each interrupt needs to trigger a context switch. For example, when the RTC interrupts, the context will switch between saving the register state and restoring the register state, which takes multiple switching times. When multiple short interrupts of the same type are merged into one interrupt, it only takes one context switch time to implement the interrupt service. At the same time, the merged interrupt events can be processed in batches because of the same type or the same processing action, avoiding frequent wake-up of the interrupt service program and improving system stability.

[0133] Furthermore, when merging multiple interrupts, it is necessary that all the interrupts to be merged correspond to low-priority interrupts. Since low-priority interrupts have lower requirements for processing timeliness and processing responsiveness, they can also be merged. However, high-priority interrupts have higher requirements for processing timeliness and the timeliness of processing response, so they cannot be merged.

[0134] In some other embodiments, the interruption optimization module is further configured to: Determine whether the interrupt source is the ECG data acquisition module or the motion data acquisition module; If so, get the current timestamp based on the event information; When the interrupt source is the ECG data acquisition module, the motion signal of the corresponding time is marked based on the timestamp; When the interrupt source is a motion data acquisition module, the electrocardiogram signal of the corresponding time is marked based on the timestamp.

[0135] In an embodiment of the present application, the DRDY pin (data ready) of the AEF ECG chip is electrically connected to the trigger input pin INT2 of the six-axis sensor. When the AEF ECG chip completes sampling of ECG data, the rising edge of the DRDY signal triggers the six-axis sensor LSM6DSLTR to synchronously collect a motion signal (acceleration data and angular velocity data) and bind them. The sampling time of the two is recorded by the RTC module.

[0136] By comparing the synchronously collected motion data and ECG data, when any module generates event information and serves as an interrupt source, if the amplitude of the corresponding event information is greater than the preset value, the data of another corresponding time point will be marked. For example, when the six-axis sensor detects an acceleration greater than 2g, the ECG data at the corresponding time will be marked and recorded as "suspected interference"; when the ECG data reflects a sharp increase in heart rate, the motion data at the corresponding time will be marked and recorded as "suspected interference."

[0137] Through time synchronization, accurate correlation of "motion-ECG" data is achieved. When any of the two key factors, motion data and heartbeat data, is abnormal, the other data is synchronously marked to determine whether the abnormal heartbeat is caused by changes in motion, and whether changes in motion data have affected the ECG data.

[0138] Furthermore, when an interruption exception occurs in any of the ECG data and motion data, the combined data of the events before and after the abnormal event (abnormal data + marker data) is constructed as key data and stored in a dedicated partition of the SD NAND Flash.

[0139] like Figure 2 and Figure 3 As shown, the present application also discloses an electrocardiogram recorder, including a host integrating the above-mentioned portable multi-lead electrocardiogram monitoring system, and also including a plurality of monitoring patches electrically connected to the host, wherein the monitoring patches include at least an auxiliary neutral lead, a plurality of simulated limb leads and a plurality of chest leads.

[0140] The monitoring patch is connected to the host through the lead. At the same time, the host and each lead are also provided with an adhesive sheet, which is used to stick the host and each lead on the user's body.

[0141] Furthermore, in the embodiment of the present application, each monitoring patch and the corresponding adhesive patch together form a circular lead electrode. The monitoring patch can also be designed into any shape such as a matrix or triangle, as long as it does not affect the adhesive effect and ECG recording effect.

[0142] The electrocardiogram recorder in the embodiment of the present application is a 12-lead portable monitor, and the 12-lead electrocardiogram data is calculated from the electrocardiogram data monitored by 10 electrode patches.

[0143] The 10 electrode patches in this application include an auxiliary neutral electrode R, an electrode R simulating a right arm lead, an electrode L simulating a left arm lead, an electrode F simulating a left leg lead, chest electrode C1, chest electrode C2, chest electrode C3, chest electrode C4, chest electrode C5, and chest electrode C6.

[0144] Among them, electrode R is pasted on the right chest infraclavicular fossa area when working, electrode N is pasted on the middle midline subclavicle when working, electrode L is pasted on the left chest infraclavicular fossa area when working, electrode F is pasted on the right chest costal arch position when working, electrode C1 is pasted on the 4th intercostal space on the right edge of the sternum when working, electrode C2 is pasted on the 4th intercostal space on the left edge of the sternum when working, electrode C3 is pasted on the middle position of the line connecting the 4th intercostal space on the left edge of the sternum and the 5th intercostal space on the left midclavicular line when working, electrode C4 is pasted on the 5th intercostal space on the left midclavicular line when working, electrode C5 is pasted on the 5th intercostal space on the left anterior axillary line when working, and electrode C6 is pasted on the 5th intercostal space on the left midaxillary line when working.

[0145] By simulating limb electrodes through chest R (RA), L (LA), and F (LL / RL), the complexity of wearing is reduced, while still being able to collect signals similar to "leads I, II, and III".

[0146] The auxiliary neutral electrode serves as a reference point with approximately zero potential. The other leads use the neutral electrode as a reference to calculate the relative voltage difference between the cardiac electrical signals of the other electrodes and the neutral electrode.

[0147] The potential difference measured by lead R (simulating the right arm RA) relative to N = VR; The potential difference measured by lead L (simulating the left arm LA) relative to N = VL; The potential difference measured in lead F (simulating the left leg LL) relative to lead N = VF.

[0148] The potential difference data of leads I, II, and III can be obtained by calculating the difference between the relative voltage differences of the simulated limb electrodes.

[0149] Lead I (potential difference between LA and RA) = VL - VR (because LA potential ≈ VL, RA potential ≈ VR, the difference is the lead I signal); Lead II (LL-RA potential difference) = VF - VR (similarly, LL potential ≈ VF, RA potential ≈ VR, the difference is the lead II signal).

[0150] Lead III = II-I, i.e., the potential difference between LL and LA, corresponds to the traditional lead III; Lead aVR = -(I + II) / 2 (pressurized unipolar right upper limb lead, reflecting the electrical activity of the right side of the heart); Lead aVL = I-II / 2 (pressurized unipolar left upper limb lead, reflecting electrical activity on the left side of the heart); Lead aVF=II-I / 2 (pressurized unipolar left lower limb lead, reflecting the electrical activity of the inferior wall of the heart).

[0151] C1-C6 corresponds to V1-V6, completely covering the electrical activity of the anterior and lateral walls of the heart, meeting the detection needs of dynamic ECG monitoring for myocardial ischemia and arrhythmia.

[0152] The implementation principle is: like Figure 2 and Figure 4 As shown, the integrated configuration of a portable small ECG recorder is realized, and the process of low-power, small-volume ECG data acquisition, processing, analysis, and transmission is realized from the hardware and embedded levels. The ECG recorder obtained based on the system integration meets the requirements of portability and multi-lead data acquisition and analysis, and is more stable and comprehensive for ECG monitoring based on a small volume.

[0153] It should be understood that although the steps in the flowcharts of the accompanying drawings are shown in sequence as indicated by the arrows, these steps are not necessarily performed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps and they may be performed in other orders.

[0154] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A portable multi-lead ECG monitoring system, characterized in that: include: An ECG data acquisition module, electrically connected to a plurality of lead electrodes to collect ECG signals and perform digital-to-analog conversion on the ECG signals; A motion data acquisition module, configured to acquire motion signals, wherein the motion signals include at least acceleration and posture; a data processing module, electrically connected to the ECG data acquisition module and the motion data acquisition module, for acquiring the acquired ECG signals and motion signals to perform processing including but not limited to feature extraction, data filtering, data compression, and interrupt optimization; A data storage module, electrically connected to the data processing module, for acquiring and writing the processed electrocardiogram signal and motion signal into different regions for storage; The data transmission module is used to connect the data processing module to an external device via wired and / or wireless communication to achieve bidirectional data transmission.

2. The portable multi-lead ECG monitoring system according to claim 1, characterized in that: The data processing module includes a feature extraction unit, a data filtering unit and a pre-built-in DSP instruction set, specifically: The data filtering unit calls a signed multiplication-accumulation instruction in the DPS instruction set to calculate a channel filter value for the channel in each register; The feature extraction unit calls the differential threshold method in the DPS instruction set to calculate the difference between the original sampling values ​​of adjacent sampling points, and determines the starting point of the QRS wave based on the number of times the difference between the original sampling values ​​is greater than a preset value; The feature extraction unit calls the multiplication and accumulation instruction in the DPS instruction set to calculate the sliding window mean of the RR interval corresponding to each of the original sampling value differences; The feature extraction unit calls a divider instruction in the DPS instruction set and calculates a heart rate value based on a sliding window mean of the RR interval.

3. The portable multi-lead ECG monitoring system according to claim 1, characterized in that: The data processing module includes a data compression unit, which is used to: Obtaining original sampling values ​​corresponding to each channel, wherein the channel corresponds to the electrocardiogram signal and the motion signal; Calculating a first difference between the current raw sampling value and the previous raw sampling value to generate an electrocardiogram data stream and a motion data stream; Obtaining timestamps corresponding to the electrocardiogram data stream and the motion data stream for data organization, and obtaining a write frame of fixed byte length after the data organization to achieve single-channel data compression, wherein the write frame includes at least a timestamp, data stream content, a packet sequence number, a check code, and a first compression tag; Based on the first difference, the corresponding quantization step size is dynamically matched in a preset step size table, and the corresponding index adjustment rule is associated.

4. The portable multi-lead ECG monitoring system according to claim 1, characterized in that: The data processing module includes a data compression unit, which is further configured to: Obtaining the channel stability corresponding to each of the ECG signals and each of the motion signals, and using the channel with the highest stability as the ECG reference channel and the motion reference channel, respectively; Calculate second differences between the original sampling values ​​in the other channels and the ECG reference channel and the motion reference channel based on the timestamp to generate an ECG inter-channel data stream and a motion inter-channel data stream; The timestamps corresponding to the data streams between the ECG channels and the data streams between the motion channels are obtained for data organization. After the data organization, a write frame with a fixed byte length is obtained to achieve inter-channel data compression. The write frame includes at least a timestamp, data stream content, a packet sequence number, a check code, and a second compression tag.

5. The portable multi-lead ECG monitoring system according to claim 3 or 4, characterized in that: The data transmission module includes a wired transmission module and a wireless communication module, wherein: The data processing module determines whether the level of the charging IO port is high. If so, it controls the analog switch to open a path between the data storage module and the data processing module, and mounts the data processing module as a USB flash drive to read the electrocardiogram signal and the motion signal through the wired transmission module; The wireless communication module is connected to the external device via Bluetooth for wireless transmission. The wireless communication module is used to transmit the electrocardiogram signal, the motion signal and / or device information to the external device, and is also used to obtain the correction time and software package issued by the external device.

6. The portable multi-lead ECG monitoring system according to claim 1, characterized in that: The data processing module further includes an interruption optimization unit, which is specifically configured to: Predefine an interrupt priority rule, wherein the interrupt priority rule includes a priority matching item and a priority raising item; Obtaining event information triggered by each module and identifying the interrupt source corresponding to the event information; Matching the interrupt source in the priority matching items to obtain a corresponding first priority; Obtaining simultaneously triggered combined event information, and determining whether the combined event information completely matches the priority boosting item; if so, configuring a corresponding second priority for the combined event information, wherein the second priority is greater than the first priority of each independent event information in the combined event information; Determine whether the priority of the currently triggered interrupt source is greater than the priority of the current interrupt source; If it is greater, the current interrupt source is interrupted and forced to be suspended and matched to the processing action corresponding to the currently triggered interrupt source for execution, and the processing action corresponding to the suspended interrupt source is resumed after the processing action is completed.

7. The portable multi-lead ECG monitoring system according to claim 6, characterized in that: The first priority of the interrupt source corresponding to each of the event information constituting the combined event information is lower than the preset priority.

8. The portable multi-lead ECG monitoring system according to claim 7, characterized in that: The interruption optimization unit is further configured to: Obtaining the timestamp corresponding to each event information; If the timestamps are all within a preset time range and the event information corresponds to the same interrupt source or the same processing action, the event information is interrupt-merged and matched with the processing action once for parallel processing.

9. The portable multi-lead ECG monitoring system according to claim 8, characterized in that: The interrupt optimization module is further configured to: Determining whether the interrupt source is the electrocardiogram data acquisition module or the motion data acquisition module; If yes, obtaining the current timestamp based on the event information; When the interrupt source is the electrocardiogram data acquisition module, marking the motion signal at the corresponding time based on the timestamp; When the interrupt source is the motion data acquisition module, the electrocardiogram signal at the corresponding time is marked based on the timestamp.

10. An electrocardiogram recorder, characterized in that: It includes a host integrating the portable multi-lead ECG monitoring system as described in any one of claims 1 to 9, and also includes a plurality of monitoring patches electrically connected to the host, wherein the monitoring patches include at least an auxiliary neutral electrode, a plurality of simulated limb electrodes and a plurality of chest electrodes.

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