Heart beat signal identification method and device of temporary pacemaker and electronic equipment

Abstract

The invention relates to the technical field of medical equipment, and provides a heart beat signal identification method and device of a temporary pacemaker and electronic equipment. The heart beat signal identification method comprises the following steps: acquiring a data signal of a time window with a set length, and identifying the positions of a wave crest and a wave trough with the maximum amplitude in the section of signal; calculating an amplitude difference between the wave crest and the wave trough as a first amplitude V-pp, and recording a time interval between the wave crest and the wave trough as an actual window length T-actual; mapping the actual window length T-actual into a standard time window through amplitude standardization transformation to obtain a standardization amplitude Vn; and comparing the standardized amplitude with a preset sensing sensitivity threshold value to realize heart beat signal identification. According to the invention, the contradiction between excessive perception and insufficient perception can be solved at the same time, and the perception reliability of the temporary pacemaker in various clinical environments is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of medical devices, in particular to a heartbeat signal recognition method and device based on a temporary pacemaker and an electronic device. BACKGROUND

[0002] A cardiac pacemaker is an important medical device for treating arrhythmia, which stimulates the heart to beat by sending a small electrical pulse to the heart to ensure the normal function of the heart. A temporary cardiac pacemaker is a medical device that connects directly to the heart through an electrode wire to sense the heart signal and provide temporary pacing support. Its basic structure mainly includes three core parts: a pulse generator, an electrode wire system and a sensing and pacing circuit. The pulse generator is responsible for generating adjustable electrical pulse signals and is equipped with a digital display interface for parameter setting and waveform monitoring. The electrode wire is connected to the generator for signal acquisition. The sensing and pacing circuit is used for amplification, filtering and identification processing of weak intracavity electrocardio signals.

[0003] The temporary cardiac pacemaker collects real-time cardiac electrical signals through the electrode wire, and after filtering and amplification, sends them to the sensing and judgment module. When the amplitude of the autonomous heartbeat signal is detected to exceed the set sensing sensitivity, the system will immediately inhibit the emission of the pacing pulse and reset the pacing timing period; if no effective heartbeat is sensed within the set escape interval (such as 1000ms period corresponding to 60 times / min), the pulse generator will emit a pacing pulse according to the preset parameters.

[0004] The existing temporary cardiac pacemaker still has some limitations in sensing and judging the heart state. At present, the main sensing technology is based on the threshold comparison method of amplitude, that is, when the amplitude of the intracardiac electrical signal exceeds a set sensing sensitivity threshold, it is determined as an effective heartbeat, and the emission of the next pacing pulse is inhibited. Threshold comparison method in processing variable morphology electrocardio signals faces the following challenges: if a lower threshold is set to improve sensitivity, although low amplitude heartbeats can be captured, narrow pulse noise or large T waves with comparable amplitudes are also likely to be misjudged as effective heartbeats, leading to excessive sensing, inappropriate inhibition of pacing pulse emission, and risk of cardiac arrest. If a higher threshold is set to resist interference, although noise can be suppressed, it will inevitably lead to the missed identification of real heartbeats with lower amplitudes (such as ventricular escape), resulting in insufficient sensing and causing the pacemaker to compete with the heart rhythm, which may induce malignant arrhythmia.

[0005] Therefore, there is an urgent need for a heartbeat signal recognition method that can avoid both excessive sensing and insufficient sensing. SUMMARY

[0006] The present application aims to overcome the inherent defects of the single amplitude sensing technology of the existing temporary pacemaker, and provides a heart beat signal identification method. The method can effectively identify the heart beat signal when facing the ECG signal with variable morphology and complex noise, solve the problems of oversensing and undersensing, and improve the sensing reliability of the temporary pacemaker in various clinical environments.

[0007] According to a first aspect of the present application, a method for identifying an ECG signal of a temporary pacemaker is provided, comprising: obtaining a data signal of a set length of time window, and identifying the positions of the maximum amplitude peaks and troughs in the signal segment; calculating the amplitude difference of the peaks and troughs as a first amplitude V-pp, and recording the time interval between the peaks and troughs as an actual window length T-actual; mapping the actual window length T-actual to a standard time window through amplitude standardization transformation to obtain a normalized amplitude V_n; comparing the normalized amplitude with a preset sensing sensitivity threshold to realize the identification of the heart beat signal.

[0008] In some embodiments, the mapping of the actual window length to a standard time window through amplitude standardization transformation to obtain a normalized amplitude comprises: setting a standard reference duration T_standard; comparing the actual window length T-actual with the standard reference duration T_standard to classify the waveform signal corresponding to the actual window length T-actual into a wide signal and a steep signal; for the wide signal, determining the normalized amplitude of the wide signal according to the average change rate of the waveform signal corresponding to the actual window length T-actual and the standard reference duration T_standard; for the steep signal, taking the original amplitude corresponding to the actual window length as the normalized amplitude.

[0009] In some embodiments, the classification of the waveform signal corresponding to the actual window length into a wide signal and a steep signal by comparing the actual window length with the standard time reference comprises: when the actual window length T-actual is greater than or equal to the standard reference duration T_standard, the waveform signal corresponding to the actual window length is the wide signal; when the actual window length T-actual is less than the standard reference duration T_standard, the waveform signal corresponding to the actual window length is the steep signal.

[0010] In some embodiments, the step of determining the normalized amplitude of the wide signal according to the average rate of change of the actual window length T-actual corresponding waveform signal and the standard reference time length T_standard comprises: calculating the normalized amplitude of the wide signal by V_normalized = V_pp × (T_standard / T_actual); wherein the ratio of the first amplitude V-pp and the actual time window length T-actual V_pp / T_actual is the average rate of change of the actual window length corresponding waveform signal.

[0011] In some embodiments, the step of comparing the normalized amplitude with the preset perceptual sensitivity threshold to achieve the identification of the heart beat signal comprises: if V_n >= perceptual sensitivity threshold, then it is determined as an effective heart beat, the pacemaker suppresses the pulse emission and resets the refractory period.

[0012] if V_n < perceptual sensitivity threshold, then it is determined as noise or invalid signal, the pacemaker prepares to emit pulse according to the preset interval.

[0013] In some embodiments, before acquiring the data signal of a set length of time window, it further comprises: acquiring the electrocardio signal by point-by-point sliding fixed length window; the fixed length is the set length.

[0014] In some embodiments, the step of mapping the actual window length T-actual to a standard time window by amplitude normalization transformation to obtain the normalized amplitude V_n further comprises: performing effective pulse width test on the signal corresponding to the actual window length, and setting the normalized amplitude V_n of the signal not meeting the pulse width to zero.

[0015] In some embodiments, the step of performing effective pulse width test on the signal corresponding to the actual window length comprises: determining the positions of the wave peak and wave trough in the actual window length; calculating the wave peak amplitude Vp and wave trough amplitude Vv; defining the effective pulse width, which is the time difference between the position of the wave peak and the position of the intermediate threshold (Vp + Vv) / 2 of the wave peak amplitude Vp and wave trough amplitude Vv; if the effective pulse width is greater than the preset effective pulse width threshold, it is considered that the effective pulse width test is passed; If the time difference is less than a preset valid pulse width threshold, it is considered that the valid pulse width test fails.

[0016] According to a second aspect of the present application, a heart beat signal sensing device of a temporary pacemaker is also provided, comprising: a signal collection module, configured to acquire a data signal of a time window with a preset length, and identify the positions of a wave peak and a wave trough with the largest amplitude in the signal segment; a calculation module, configured to calculate the amplitude difference between the wave peak and the wave trough as a first amplitude V-pp, and record the time interval between the wave peak and the wave trough as an actual window length T-actual; a standardization transformation module, configured to map the actual window length T-actual to a standard time window through amplitude standardization transformation, to obtain a normalized amplitude V_n; a comparison module, configured to compare the normalized amplitude with a preset sensing sensitivity threshold, to realize the identification of the heart beat signal.

[0017] According to a third aspect of the present application, an electronic device is also provided, comprising: at least one processor; and a memory, which stores a computer program capable of running in the processor, and the processor executes the program to execute the aforementioned heart beat signal identification method.

[0018] The heart beat signal identification method described in the present application maps the signals with similar amplitudes but different morphologies to a comprehensive evaluation system which integrates the amplitude and other evaluation factors, and through the amplitude standardization transformation, the amplitude of the easy-missed signal is improved, while the amplitude of the similar interference signal is compressed, so that the easy-missed signal and other signals have a large amplitude difference. The sensing threshold is selected in the range of the amplitude difference, the easy-missed signal is effectively extracted, and other interference signals are effectively suppressed. Since the amplitudes of the signals with similar amplitudes are effectively distinguished through the amplitude standardization transformation, the sensing threshold selected based thereon can effectively distinguish the easy-missed signal and the interference signal, so that the heart beat signal identification method described in the present application can simultaneously avoid the defects of sensing over and sensing under, and greatly improve the sensing reliability of the temporary pacemaker in various clinical environments.

[0019] In addition, the present application also provides a heart beat signal identification device and an electronic device, which can also achieve the above technical effects, and will not be described here. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to make the objectives, technical solutions and advantages of the present application clearer, the following will further describe the embodiments of the present application with reference to the accompanying drawings.

[0021] Figure 1 is a schematic diagram of QRS wave in electrocardiosignal; Figure 2 is a schematic diagram of T wave in electrocardiosignal; Figure 3 is a schematic diagram of premature ventricular contraction in electrocardiosignal; Figure 4 is a cavity electrocardiosignal amplitude conversion diagram obtained by using single threshold comparison method in prior art; Figure 5 is a cavity electrocardiosignal schematic diagram using higher threshold in prior art; Figure 6 is a cavity electrocardiosignal schematic diagram using lower threshold in prior art; Figure 7 is a flow chart of a heartbeat signal recognition method according to one embodiment of the present application; Figure 8 shows a schematic diagram of electrocardiosignal after standardizing amplitude processing of electrocardiosignal; Figure 9 is a flow chart of a heartbeat signal recognition method according to another embodiment of the present application; Figure 10 is a flow chart of a heartbeat signal recognition method according to an embodiment of the present application; Figure 11 is an internal structure diagram of an electronic device shown in one embodiment of the present application. DETAILED DESCRIPTION

[0022] In order to make the objectives, technical solutions and advantages of the present application clearer, the following will further describe the embodiments of the present application with reference to the accompanying drawings.

[0023] It should be noted that all the expressions of "first" and "second" in the embodiments of the present application are used to distinguish two same name non-identical entities or non-identical parameters, and it can be seen that "first" and "second" are only for the convenience of description, and should not be understood as a limitation of the embodiments of the present application, and the subsequent embodiments will not be described one by one.

[0024] The temporary cardiac pacemaker directly connects with the heart through an electrode lead wire to sense the heart signal. The intracavity electrocardio signal is an electrical signal generated by the myocardial contraction and relaxation in the heart cavity, reflecting the activity of the heart. Different characteristics of the intracavity electrocardio signal can reflect different pathological characteristics of the heart.

[0025] Specifically, the intracavity electrocardio signal includes QRS wave, T wave, etc. The R wave in the QRS complex reflects the potential change process of ventricular depolarization, as shown in FIG. 1, wherein the bold part is the QRS wave in the electrocardio signal. Figure 1 The T wave reflects the repolarization process of the ventricle, as shown in FIG. 2, wherein the bold part is the T wave in the electrocardio signal. Figure 2 Premature ventricular contraction is a special R wave, as shown in FIG. 3, wherein the bold part is the premature ventricular contraction in the electrocardio signal. The premature ventricular contraction is the premature depolarization of the ventricle caused by ectopic beats from one ventricle, which is a ventricular event that does not occur in sequence. Figure 3

[0026] The intracavity electrocardio signal is obtained after the original electrocardio signal is preprocessed. In order to facilitate the analysis and comparison of the signal, one of the processing methods is as follows: after removing the power frequency interference, myoelectric interference and baseline drift and other problems, the amplitude of the electrocardio signal is processed. The specific processing method is as follows: at a time node, a fixed length time window is selected and the electrocardio signal value in the time window is obtained; the difference between the peak and the trough in the fixed length time window corresponding to the time node is calculated as the amplitude of the time node for recording; the fixed length time window is slid point by point to obtain the amplitude corresponding to each time node, and the intracavity electrocardio signal amplitude conversion diagram shown in FIG. 4 is obtained. Figure 4

[0027] The amplitude threshold comparison method described in the existing mainstream sensing technology is that, in the amplitude of the intracavity electrocardio signal shown in FIG. 4, a sensing threshold is set, as shown by the horizontal line L in FIG. 5. Figure 4 When the amplitude of the intracavity electrocardio signal exceeds the set sensing threshold, it is determined as an effective heart beat, and the next pacing pulse is inhibited. Figure 5

[0028] The threshold comparison method faces the following problems when processing electrocardio signals with variable morphology (such as low-amplitude but steep-slope premature ventricular contraction, high-amplitude but slow-changing T wave or baseline drift, and high-frequency myoelectric interference, etc.): if a lower threshold is set to improve sensitivity, as shown by the sensing threshold corresponding to the horizontal line L1 in FIG. 6. Although the lower sensing threshold can capture low-amplitude heart beats, it is also easy to misjudge the narrow pulse noise (not shown in the figure) or T wave with similar amplitude as an effective heart beat, leading to over-sensing, inappropriate inhibition of the pacing pulse, and causing the risk of cardiac arrest. For example, as shown in FIG. 7, the sensing threshold corresponding to the horizontal line L1 is set to be lower than the amplitude of the T wave, so that the T wave is misjudged as an effective heart beat, and the next pacing pulse is inhibited. Figure 6 Figure 6 ​​​​For sensing a ventricular premature beat (a type of abnormal heart beat), a lower threshold (horizontal line L1) is set. Since the T-wave amplitude is comparable to the ventricular premature beat amplitude, the T-wave is likely to be sensed, resulting in a false sensing.

[0029] If a higher threshold is set to suppress noise, a real heart beat with a lower amplitude (e.g., a ventricular premature beat, Figure 5 is likely to be missed, resulting in an undersensing, causing the pacemaker to compete with the native rhythm and possibly inducing malignant arrhythmias.

[0030] The present application provides a novel heart beat signal identification method. The method effectively solves the problem that a single threshold cannot avoid the contradiction between oversensing and undersensing when facing ECG signals with variable morphology and complex noise, and improves the sensing reliability of temporary pacemakers in various clinical environments.

[0031] In the method for determining a heart beat signal in an intracavity ECG signal described in the present application, after removing power frequency interference, myoelectric interference, baseline drift and other problems, a fixed-length time window is used to obtain the signal in the time window corresponding to each time point, and the signal in each time window is processed to obtain an amplitude conversion graph different from the prior art. It should be noted that the fixed-length time window sliding point by point can be understood as the time span of the data window being constant, but the data at the beginning and end is updated in real time due to the sliding of the data and the fixed number of data.

[0032] Specifically, in one embodiment, referring to Figure 7 The present application provides a heart beat signal identification method, specifically comprising: Step 101, obtaining a data signal of a set length of time window, and identifying the positions of the maximum amplitude peaks and troughs in the time window.

[0033] In this step, the setting of the time window length is crucial. The width of human QRS wave is usually 60ms~100ms, and the upper limit of human QRS wave width is about 120ms. The width of T wave is usually 100ms~250ms, and according to the industry experience value, the limit value of human T wave can reach 300ms. The heart beat signal is usually identified as QRS wave, so the lower limit of the time window length should be greater than half of the normal QRS wave width, and considering that the time window length covers the peak and trough as much as possible, the upper limit of the time window length should be significantly greater than the lower limit of the time window length.

[0034] For the selection of the upper limit of the time window, the total width of the T wave can be referred to for setting. This is because in the human electrocardiosignal category, the width range of the T wave is the largest, and although the T wave changes slowly as a whole, there may be relatively rapid changes in a certain segment of its rising or falling branch. If the length of the calculation time window is set too small, only the fastest changing local segment of the T wave may be captured, and a complete T wave cannot be covered. The peak-valley difference identified is not always the true peak-valley difference of the T wave, i.e. the T wave cannot be fully identified, resulting in signal omission and inaccurate identification. Therefore, the length of the time window is preferably set to a value sufficient to cover the main part of the T wave.

[0035] Considering the symmetry of the amplitude signal, in a specific value selection method, half of the width of the widest waveform in the electrocardiosignal is selected as the set value of the time window. Referring to the upper limit width range of the T wave, which is 250ms~300ms, the value range of the set value of the time window can be selected as 125 ms~150ms.

[0036] After determining the set value of the time window (e.g. 150ms), the time span of the time window is unchanged, and the wave peak and wave valley with the largest amplitude in the time window are identified.

[0037] This step aims to capture the most representative rapidly changing segment of the signal.

[0038] Step 102, calculate the amplitude difference between the wave peak and the wave valley as the first amplitude V-pp, and record the time interval between the wave peak and the wave valley as the actual window length T-actual. After identifying the positions of the wave peak and the wave valley with the largest amplitude in the current time window in step 101, the amplitude difference between the wave peak and the wave valley is calculated, i.e. the first amplitude V-pp.

[0039] Step 103, map the actual window length T-actual to a standard time window through amplitude standardization transformation to obtain the standardized amplitude V_n, i.e. signal intensity standardization calculation.

[0040] Specifically, mapping the actual window length T-actual to a standard time window through amplitude standardization transformation to obtain the standardized amplitude V_n includes: A standard reference duration T_standard is set. The waveform signal corresponding to the actual window length T-actual is classified as a wide signal and a steep signal by comparing the actual window length T-actual with the standard reference duration T_standard. For the wide signal, a normalized amplitude of the wide signal is determined according to the average change rate of the waveform signal corresponding to the actual window length T-actual and the standard reference duration T_standard; and for the steep signal, the original amplitude corresponding to the actual window length is taken as the normalized amplitude V_n.

[0041] For selection of the standard reference duration T_standard, according to Figures 1-3 The characteristics of various electrocardiosignals shown in the table can be known as follows: The QRS wave has concentrated energy, a rapidly rising waveform, a certain width and a relatively high amplitude, and the average change rate (the ratio of V_pp / T_actual) is relatively fast.

[0042] The premature ventricular contraction rises fast and falls slow, and the amplitude is relatively low compared with the normal QRS wave, and the average change rate (the ratio of V_pp / T_actual) is also relatively fast.

[0043] The T wave amplitude is equivalent to the premature ventricular contraction, and the average change rate of the T wave is slow.

[0044] It can be known by comparison that the premature ventricular contraction can be distinguished from the T wave by the average change rate, the identified premature ventricular contraction is taken as the heart beat signal, and the T wave is inhibited.

[0045] The normalized time window T-standard is selected from the waveform with the fastest average change rate, and the selection rule is that the symmetry of the waveform is considered, the 1 / 2 of the waveform width is first selected, the 1 / 4-1 / 3 of the waveform width with the fastest average change rate is selected to ensure that the selected time window covers the part with the fastest change rate, and the purpose is to enable the amplitudes of all subsequent waveforms to be normalized and converted, to realize full coverage of signal conversion and prevent missed identification.

[0046] For example, if the average change rate of the QRS wave is the fastest among the QRS wave, the T wave and the premature ventricular contraction. Taking the QRS wave width range of 60ms-100ms as an example, since the maximum amplitude of the QRS signal is usually at the R wave, and in some available parameter examples, when the QRS width is 105ms, the R wave width is 60ms. The set value of the normalized time window T-standard is 60ms*(1 / 4-1 / 3)=15-20ms.

[0047] After determining the standardization time window T-standard, the actual window length is compared with the standard time reference to determine whether the waveform signal corresponding to the actual window length is a wide signal or a steep signal. Specifically, when the actual window length T-actual is greater than or equal to the standard reference time T_standard, the waveform signal corresponding to the actual window length is a wide signal; and when the actual window length T-actual is less than the standard reference time T_standard, the waveform signal corresponding to the actual window length is a steep signal.

[0048] For a wide signal, a standardization amplitude V_n of the wide signal is determined according to the average change rate of the waveform signal corresponding to the actual window length T-actual and the standard reference time T_standard. Specifically, when T_actual >= T_standard, the standardization amplitude V_n of the wide signal is V_pp x (T_standard / T_actual). The ratio of the first amplitude V_pp and the actual window length T-actual, V_pp / T_actual, is the average change rate of the waveform signal corresponding to the actual window length. This calculation formula "compresses" the strength of the wide signal to the standard time for evaluation, avoiding the dominance of the wide signal due to its long duration.

[0049] For a steep signal, the original amplitude corresponding to the actual window length is taken as the standardization amplitude. Specifically, when T_actual < T_standard, the standardization amplitude V_n of the steep signal is V_pp. For a steep signal, its original amplitude is directly used, and the purpose is to prevent unreasonable amplification of high-frequency narrow pulse noise. In another processing manner, for a sudden signal, its standardization amplitude V_n can also be directly set to zero to prevent interference.

[0050] Figure 8 An electrocardiosignal after standardization amplitude processing is shown, and a waveform of the electrocardiosignal is shown. Figure 8 It can be seen that some wide signals (small average change rate) and high-frequency narrow pulse noise (not shown in the figure) are "compressed" to the standard time and are appropriately shrunk in amplitude, and the amplitude of the easy-to-miss signal is raised. In the converted amplitude diagram, the perception sensitivity threshold L2 is selected, and the effective screening of the easy-to-miss signal can be realized, and the defects of over-perception and under-perception can be avoided at the same time.

[0051] In step 104, the standardization amplitude is compared with the preset perception sensitivity threshold, and the recognition of the heart beat signal is realized.

[0052] After the standardization amplitude V_n is calculated, the standardization amplitude is compared with the preset perception sensitivity threshold, and the step of recognizing the heart beat signal is realized, including: If V_n >= sensing sensitivity threshold (different for each patient, can be measured), it is determined as a valid heart beat, the pacemaker inhibits the pulse emission and resets the refractory period.

[0053] If V_n < sensing sensitivity threshold, it is determined as noise or invalid signal, the pacemaker prepares to emit a pulse according to the preset interval.

[0054] The threshold setting of the sensing sensitivity and the signal screening can refer to Figure 8 , wherein the threshold of the sensing sensitivity is L2.

[0055] From the above step content, it can be known that the application fuses two key features of the signal amplitude and the average change rate to form a comprehensive evaluation index, and converts the signals in the time window into wide signals and steep signals according to the evaluation index. For the wide signal (the amplitude is similar to the easy-to-miss signal, but the average change rate is different from the easy-to-miss signal), the amplitude V_pp in any short time window is very small, and the corresponding standardized amplitude V_n is also low, so it will not be misjudged. For the steep signal (the sharp glitch interference signal in the electrocardio signal), the actual time window is extremely short, and according to the rule, the steep signal is not amplified or directly set to zero, and the corresponding standardized amplitude V_n of the steep signal is also low, and the sensing is not easy to trigger. Therefore, it can be known that the amplitude standardization conversion of the application effectively distinguishes the amplitudes of the signals with similar amplitudes, and the sensing threshold selected based on this can effectively distinguish the easy-to-miss signal and the interference signal, so that the heart beat signal recognition method described in the application can avoid the defects of sensing excess and sensing deficiency at the same time.

[0056] According to another embodiment of the application, a more optimized heart beat signal recognition method is also provided, which can refer to Figure 9 . As can be known from the heart beat signal recognition method shown in Figure 7 , the heart beat signal recognition method shown in Figure 9 further comprises the step 203 of performing effective pulse width verification on the signal corresponding to the actual window length, and setting the standardized amplitude V_n of the signal not meeting the pulse width to zero.

[0057] Specifically, in some embodiments, the effective pulse width verification on the signal corresponding to the actual window length comprises: determining the positions of the wave peaks and the wave troughs in the actual window length, calculating the wave peak amplitude Vp and the wave trough amplitude Vv, defining the effective pulse width, the effective pulse width being the time difference between the position of the wave peak and the position of the intermediate threshold (Vp + Vv) / 2 of the wave peak amplitude Vp and the wave trough amplitude Vv, if the effective pulse width is greater than the preset effective pulse width threshold, it is considered that the signal corresponding to the actual window length passes the effective pulse width verification, and if the time difference is less than the preset effective pulse width threshold, it is considered that the signal corresponding to the actual window length does not pass the effective pulse width verification.

[0058] For the effective pulse width, step 204 is continued; if the effective pulse width is less than the preset minimum effective pulse width threshold, the signal is considered as a spike interference, and the normalized amplitude (V_normalized) is forced to be zero.

[0059] The heart beat signal recognition method in the present application is described in detail below through a flow chart.

[0060] Figure 10 For a heart beat signal recognition method flow chart according to an embodiment of the present application, refer to Figure 10 , which includes: Step 1: system initialization.

[0061] Set the parameter time window minimum value T_search_min, time window maximum value T_search_max, standard reference duration T_standard, effective pulse width threshold Width_min, sensing sensitivity threshold, refractory period (for example, 250 ms), etc.

[0062] Step 2: real-time signal sampling and buffering.

[0063] The real-time signal sampling in this step refers to that the time span of the data window is unchanged, but the head and tail data are updated in real time due to the data sliding in and the fixed number of data, and the signal in each time window is buffered.

[0064] Step 3: judge whether the current is in the refractory period. If it is in the refractory period, return to step 2, if it is not in the refractory period, proceed to step 4.

[0065] After a normal ventricular muscle electrical activity, there is a refractory period. The refractory period refers to that during this period, the stimulation will not cause the myocardial cells to generate an action potential again. A normal ventricular cycle includes atrial systole, diastole, ventricular systole and diastole, and the refractory period generally lasts about 200 ms-300 ms.

[0066] Step 4, peak-valley difference detection.

[0067] In the selected time window, the actual time window T_actual, the peak position P_peak and the valley position P_valley corresponding to the maximum amplitude value are calculated in the range of T_search_min to T_search_max.

[0068] According to the positions of the peak and the valley with the maximum amplitude in the current time window, the amplitude difference between the peak and the valley is calculated as the first amplitude V-pp.

[0069] Step 5, Effective pulse width verification Width_effective.

[0070] In this step, Width_effective is calculated. In order to avoid misjudging a wide signal with only a single sharp spike at the end point as an effective signal, the effective pulse width of the signal in the current time window needs to be calculated. According to the positions of the wave peaks and wave troughs in Step 4, the wave peak amplitude Vp and the wave trough amplitude Vv are calculated, and the effective pulse width is calculated according to the definition of the effective pulse width. The effective pulse width is the time difference between the position of the wave peak and the position of the intermediate threshold (Vp + Vv) / 2 of the wave peak amplitude Vp and the wave trough amplitude Vv.

[0071] Determine whether the effective pulse width Width_effective is less than the effective pulse width threshold Width_min.

[0072] If it is less than the effective pulse width threshold, it is considered that the signal is a spike interference, the normalized amplitude V_n corresponding to the signal is forced to be zero, and the flow jumps to Step 7. If the effective pulse width is greater than the effective pulse width threshold, Step 6 is entered.

[0073] Step 6, Signal intensity normalization calculation.

[0074] If the signal in Step 5 passes the effective pulse width verification, the maximum peak-to-valley difference V_pp detected is mapped to the standard reference time T_standard to obtain the normalized amplitude V_n. The specific calculation rules are as follows: Record the time interval between the wave peak and the wave trough in the current time window as the actual window length T-actual, If T_actual >= T_standard: V_n = V_pp x (T_standard / T_actual) If T_actual < T_standard: V_n = V_pp.

[0075] Step 7, Sensing decision.

[0076] Compare the calculated normalized amplitude V_n with the preset sensing sensitivity threshold, If V_n >= sensing sensitivity threshold, execute effective cardiac response: reset and start the refractory period timer, suppress the pacing pulse, and reset the pacing interval timer.

[0077] If V_n < sensing sensitivity threshold, it is determined to be invalid, and the flow returns to Step 2.

[0078] Step 8, System response.

[0079] If the decision is valid cardiac beat, then the pacing is inhibited and the refractory period timer is reset; otherwise, the normal pacing timing continues.

[0080] Throughout the process, the pacing pulse emission logic runs independently and in parallel, which checks whether the pacing interval is overdue and not inhibited by valid cardiac beat, and if the conditions are met, the pacing pulse is emitted, and after the pulse emission, the refractory period timer is also reset and started.

[0081] The following is illustrated by specific examples.

[0082] Taking the electrocardiosignal as an example, the intracavity electrocardiosignal includes QRS wave, T wave, etc., and the premature ventricular contraction in the electrocardiosignal should be validly sensed as a special cardiac beat. The premature ventricular contraction is a special R wave, and the characteristics of the premature ventricular contraction signal are fast rising, slow falling, and relatively low amplitude compared with the normal QRS wave. For reference, see Figure 3 According to the traditional calculation method, since the amplitude of the premature ventricular contraction is very close to that of the T wave, it is difficult to consider both "missed sensing" and "false sensing" no matter how the threshold is set. For reference, see Figure 5 .

[0083] The cardiac beat signal recognition method described in the present application is as follows: 1. Length selection of the time window: The width range of the human QRS wave is usually 60 ms to 100 ms, and the width range of the T wave is usually 100 ms to 250 ms (the abnormally wide T wave can reach 300 ms). Referring to the selection standard of the length of the time window in step 101, half of the upper limit width of the T wave is taken as the length of the time window, that is, the length of the time window is 150 ms. That is, in this embodiment, the electrocardiosignal is obtained by sliding the 150 ms time window of the electrocardiosignal point by point in real time.

[0084] 2. Selection of the standardized time window T-standard: The average change rate of the QRS wave is the fastest, and according to the principle of selecting 1 / 4 to 1 / 3 of the waveform width with the fastest average change rate as the standardized time window, the standardized time window T-standard = 1 / 4*60 = 15 ms.

[0085] 3. Peak-valley difference detection: in the 150 ms time window, assuming that the actual time window T_actual of the QRS wave is 60 ms, the actual time window T_actual of the T wave is 100 ms, and the actual time window T_actual of the premature ventricular contraction is 25 ms.

[0086] The maximum amplitude of the QRS segment signal is calculated at the R wave, so the amplitude of the R wave is taken as the reference. For ease of calculation, refer to Figures 1-3The shown amplitude is taken as a reference, assuming that the first amplitude V-pp of the R wave is 1, the first amplitude V-pp of the premature ventricular contraction is 0.45 (the amplitude of the fast rising section thereof), and the first amplitude V-pp of the T wave is 0.47.

[0087] 4. Effective pulse width verification: the effective pulse width threshold Width_min is set to 5 ms, and assuming that the effective pulse width of the QRS wave is 26 ms, the effective pulse width of the R wave is 15 ms, the effective pulse width of the T wave is 57.5 ms, and the effective pulse width of the premature ventricular contraction is 10 ms, which are calculated according to the definition of the effective pulse width. Since the effective pulse widths of the QRS wave, the T wave and the premature ventricular contraction are all greater than Width_min, the four kinds of waveform signals all pass the effective pulse width verification.

[0088] 5. Signal intensity standardization calculation: T_standard=15, then The normalized amplitude V_n of the QRS wave is V_pp × (T_standard / T_actual)=1×15 / 60=0.4; The normalized amplitude V_n of the premature ventricular contraction is V_pp × (T_standard / T_actual)=0.45×15 / 25=0.36; The normalized amplitude V_n of the T wave is V_pp × (T_standard / T_actual)=0.47×15 / 100=0.09.

[0089] 6. Perception decision: setting the perception sensitivity threshold to 0.3, the T wave is effectively suppressed, the premature ventricular contraction is prominent, and the QRS wave maintains the dominant height, which takes into account the “false perception” and “missed perception”.

[0090] In some embodiments, the present application also provides a heartbeat signal identification device of a temporary pacemaker, which comprises: a signal collection module for acquiring a data signal of a set length of time window and identifying the positions of the wave peak and the wave trough with the largest amplitude in the signal; a calculation module for calculating the amplitude difference of the wave peak and the wave trough as a first amplitude V-pp and recording the time interval between the wave peak and the wave trough as an actual window length T-actual; a standardization transformation module for mapping the actual window length T-actual to a standard time window through amplitude standardization transformation to obtain a normalized amplitude V_n; and a comparison module for comparing the normalized amplitude with a preset perception sensitivity threshold to realize the identification of the heartbeat signal.

[0091] It should be noted that each module in the heartbeat signal sensing device of the temporary pacemaker described above can be implemented by software, hardware and combinations thereof, in whole or in part. The above modules can be embedded in or independent of the processor in the electronic device in hardware form, or can be stored in the memory in the electronic device in software form, so as to be called and executed by the processor to perform the operations corresponding to the above modules.

[0092] According to another aspect of the present application, an electronic device, which can be a server, is provided, and an internal structure diagram of the electronic device is shown in Figure 11 The electronic device includes a processor, a memory, a network interface and a database connected through a system bus. The processor of the electronic device is configured to provide computing and control capabilities. The memory of the electronic device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operating system and the computer program in the non-volatile storage medium to run. The database of the electronic device is configured to store data. The network interface of the electronic device is configured to communicate with an external terminal through a network connection. The computer program is executed by the processor to implement the heartbeat signal recognition method described above.

[0093] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer readable storage medium. When the computer program is executed, it can include the processes of the above-mentioned embodiments. Any reference to memory, storage, database or other medium used in the embodiments provided by the present application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration but not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM) and memory bus dynamic RAM (RDRAM) and the like.

[0094] Any combination of the technical features in the above embodiments can be made, and for the sake of brevity, not all possible combinations are described above, however, as long as the combination of the technical features does not exist in contradiction, it shall be considered within the scope of the present disclosure.

[0095] The above embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it shall not be understood as a limitation on the patent scope of the present application. It shall be pointed out that, for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, and these shall be within the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the appended claims.

Claims

1. A method of cardiac beat signal recognition for a temporary pacemaker, characterized by, The method comprises the following steps: acquiring a data signal of a time window with a set length, and identifying the positions of the maximum amplitude peak and the minimum amplitude trough in the time window; calculating the amplitude difference between the peak and the trough as a first amplitude V-pp, and recording the time interval between the peak and the trough as an actual window length T-actual; mapping the actual window length T-actual to a standard time window through amplitude normalization transformation to obtain a normalized amplitude V_n; comparing the normalized amplitude with a preset perception sensitivity threshold to identify a heart beat signal.

2. The heart beat signal recognition method according to claim 1, characterized in that, The step of mapping the actual window length to a standard time window through amplitude normalization transformation to obtain a normalized amplitude comprises the following steps: setting a standard reference duration T_standard; comparing the actual window length T-actual with the standard reference duration T_standard to classify the waveform signal corresponding to the actual window length T-actual into a wide signal and a steep signal; for the wide signal, determining the normalized amplitude of the wide signal according to the average change rate of the waveform signal corresponding to the actual window length T-actual and the standard reference duration T_standard; for the steep signal, taking the original amplitude corresponding to the actual window length as the normalized amplitude.

3. The heart beat signal recognition method according to claim 2, characterized in that, The step of comparing the actual window length with the standard time reference to classify the waveform signal corresponding to the actual window length into a wide signal and a steep signal comprises the following steps: when the actual window length T-actual is greater than or equal to the standard reference duration T_standard, the waveform signal corresponding to the actual window length is the wide signal; when the actual window length T-actual is less than the standard reference duration T_standard, the waveform signal corresponding to the actual window length is the steep signal.

4. The heart beat signal recognition method according to claim 2, characterized in that, The step of determining the normalized amplitude of the wide signal according to the average change rate of the waveform signal corresponding to the actual window length T-actual and the standard reference duration T_standard comprises the following steps: calculating the normalized amplitude of the wide signal by V_normalized = V_pp × (T_standard / T_actual); wherein the ratio V_pp / T_actual of the first amplitude V-pp and the actual window length T-actual is the average change rate of the waveform signal corresponding to the actual window length.

5. The heart beat signal recognition method of claim 1, wherein, The step of comparing the normalized amplitude with a preset perception sensitivity threshold to identify a heart beat signal comprises the following steps: if V_n >= the perception sensitivity threshold, determining that it is an effective heart beat, and the pacemaker suppresses pulse emission and resets the refractory period; if V_n < the perception sensitivity threshold, determining that it is noise or an invalid signal, and the pacemaker prepares to emit a pulse at a preset interval.

6. The heart beat signal recognition method according to any one of claims 1 to 5, characterized in that, Before acquiring a data signal of a time window with a set length, the method further comprises the following steps: The electrocardiosignal is acquired by point-by-point sliding fixed length windowing; The fixed length is the set length.

7. The heart beat signal recognition method according to claim 6, characterized in that, The actual window length T-actual is mapped into a standard time window by amplitude normalization transformation to obtain a normalized amplitude V_n. The signal corresponding to the actual window length is subjected to effective pulse width test, and the normalized amplitude V_n of the signal not meeting the pulse width is set to zero.

8. The heart beat signal recognition method according to claim 7, characterized in that, The effective pulse width test on the signal corresponding to the actual window length comprises: The positions of the wave peak and the wave trough in the actual window length are determined; The wave peak amplitude Vp and the wave trough amplitude Vv are calculated; An effective pulse width is defined, which is the time difference between the position of the wave peak and the position of the intermediate threshold (Vp + Vv) / 2 of the wave peak amplitude Vp and the wave trough amplitude Vv; If the effective pulse width is greater than a preset effective pulse width threshold, it is considered that the effective pulse width test is passed; If the time difference is less than the preset effective pulse width threshold, it is considered that the effective pulse width test is not passed.

9. A heart beat signal recognition apparatus for a temporary pacemaker, characterized by Comprise: A signal collection module is configured to acquire a data signal of a set length time window and identify the positions of the wave peak and the wave trough with the largest amplitude in the time window; A calculation module is configured to calculate the amplitude difference of the wave peak and the wave trough as a first amplitude V-pp and record the time interval between the wave peak and the wave trough as an actual window length T-actual; A normalization transformation module is configured to map the actual window length T-actual into a standard time window by amplitude normalization transformation to obtain a normalized amplitude V_n; A comparison module is configured to compare the normalized amplitude with a preset perception sensitivity threshold to realize the identification of the heart beat signal.

10. An electronic device, comprising: Comprise: At least one processor; And A memory storing a computer program capable of running in the processor, and the processor executes the program to execute the heart beat signal identification method of any one of claims 1-8.

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