Heartbeat waveform extraction device and heartbeat waveform extraction method

Abstract

To provide a heart rate waveform extractor and a heart rate waveform extraction method capable of extracting a heart rate waveform suitable for inspection of a valve disease of a heart such as aortic stenosis.SOLUTION: A heart rate waveform extractor comprises: a heart rate waveform acquiring part for acquiring a heart rate waveform including an electrocardiogram, a pulse wave, and a cardiac sound of a subject; a storage part for storing the heart rate waveform; and a heart rate waveform extraction part for reading multiple heart rates from the heart rate waveform stored in the storage part, evaluating respective heart rates in an overall state on the basis of the electrocardiogram, the pulse wave and the cardiac sound included in the multiple heart rates, extracting thereby a representative heart rate suitable for inspection of a valve disease of a heart from the multiple heart rates, and then outputting the electrocardiogram, the pulse wave and the cardiac sound included in the representative heart rate to the device which inspects the valve disease of the heart.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a cardiac waveform extraction device and a cardiac waveform extraction method for extracting cardiac waveforms for examining cardiac valve diseases such as aortic valve stenosis. [Background technology]

[0002] Aortic valve stenosis (AS) is a disease in which the aortic valve, one of the four valves in the heart that is located between the left ventricle and the aorta, becomes difficult to open due to inflammation and hardening. The number of AS patients is on the rise due to the aging population.

[0003] When the aortic valve narrows, the heart tries to overcome the narrowing and squeeze blood throughout the body, placing pressure on the left ventricle, which then becomes enlarged as a compensatory mechanism. Eventually, the left ventricle is unable to withstand the strain, leading to irreversible left ventricular dysfunction, heart failure, and sudden death.

[0004] AS can progress unnoticed, and the prognosis is poor once severe symptoms appear, so early detection and appropriate timing of surgery are essential.

[0005] Primary screening for AS is primarily performed by auscultation of the heart (the systolic murmur specific to AS).

[0006] If a doctor is unable to make a diagnosis based on a heart murmur, they will palpate the pulse (delay in the onset of the pulse wave) or perform an electrocardiogram. If these tests reveal any abnormalities, a detailed echocardiogram will be performed to make a definitive diagnosis and determine the severity of the condition.

[0007] However, experience is required for a doctor to perform cardiac auscultation accurately. Patent Document 1 discloses a technique for determining systolic murmurs using an electrocardiogram and a phonocardiogram. It is believed that this technique can automatically detect cardiac murmurs that may indicate diseases such as aortic valve stenosis, even if the doctor has no experience. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-169615 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-168074 Summary of the Invention [Problem to be solved by the invention]

[0009] When examining heart valve diseases such as aortic stenosis using an examination device, the cardiac waveform used is thought to have a significant effect on the accuracy of the examination.

[0010] However, conventional heart rate waveform extraction has focused on extracting the cleanest waveforms possible from electrocardiograms, pulse waves, and phonocardiograms, and there has been insufficient consideration given to extracting heart rate waveforms suitable for testing for heart valve diseases such as aortic stenosis.

[0011] The present invention has been made in consideration of the above points, and provides a heartbeat waveform extraction device and a heartbeat waveform extraction method that can extract a heartbeat waveform suitable for testing for heart valve diseases such as aortic valve stenosis. [Means for solving the problem]

[0012] One aspect of the cardiac waveform extraction device inspection device of the present invention is a heartbeat waveform acquisition unit for acquiring a heartbeat waveform including an electrocardiogram, a pulse wave, and a heart sound of a subject; a storage unit that stores the cardiac waveform; a heartbeat waveform extraction unit that reads out multiple heartbeats from the heartbeat waveforms stored in the storage unit, comprehensively evaluates each heartbeat based on the electrocardiogram, pulse wave, and heart sound included in the multiple heartbeats, thereby extracting a representative heartbeat from the multiple heartbeats that is suitable for testing for heart valve disease, and outputs the electrocardiogram, pulse wave, and heart sound included in the representative heartbeat to a device that tests for heart valve disease; Equipped with.

[0013] One aspect of the cardiac waveform extraction method of the present invention includes: acquiring a cardiac waveform including an electrocardiogram, a pulse wave, and heart sounds of a subject; storing the cardiac waveform; a heartbeat waveform extraction step of reading out multiple heartbeats from the stored heartbeat waveforms, comprehensively evaluating each heartbeat based on the electrocardiogram, pulse wave, and heart sounds included in the multiple heartbeats, thereby extracting a representative heartbeat from the multiple heartbeats that is suitable for testing for heart valve diseases, and outputting the electrocardiogram, pulse wave, and heart sounds included in the representative heartbeat to a device for testing for heart valve diseases; Includes. [Effects of the Invention]

[0014] According to the present invention, it is possible to realize a heartbeat waveform extraction device and a heartbeat waveform extraction method that can extract a heartbeat waveform suitable for testing heart valve diseases such as aortic valve stenosis, thereby improving the testing accuracy in devices that test heart valve diseases. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a diagram showing the overall configuration of a blood pressure pulse wave inspection device according to an embodiment. [Figure 2] FIG. 1 is a block diagram showing the main configuration of a cardiac waveform extraction device according to an embodiment. [Figure 3] Diagram explaining systolic murmur [Figure 4] FIG. 10 is a diagram illustrating the area of ​​a systolic murmur calculated by a systolic murmur area calculation unit. [Figure 5] Diagram for explaining IUT [Figure 6] 10 is a flowchart showing a procedure of a determination process performed by a determination unit. [Figure 7] A diagram showing the relationship between threshold determination by the determination unit and patients with aortic valve stenosis. [Figure 8] 1 is a flowchart illustrating the operation of a heartbeat waveform extraction unit. [Figure 9]10 is a diagram showing the first heartbeat, the final heartbeat, and the premature systolic heartbeat excluded by the first excluded heartbeat evaluation unit; [Figure 10] FIG. 10 is a diagram showing an evaluation performed by a first excluded heartbeat evaluation unit. [Figure 11] FIG. 10 is a diagram showing an evaluation performed by a second excluded heartbeat evaluation unit. [Figure 12] 12A and 12B are diagrams illustrating the evaluation performed by the third excluded heartbeat evaluation unit, in which FIG. 12A shows an electrocardiogram and FIG. 12B shows heart sounds. [Figure 13] FIG. 1 is a diagram illustrating extraction priorities performed by an extraction unit. [Figure 14] FIG. 10 is a diagram showing an example of extraction of a representative heartbeat by an extraction unit. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0017] <1> Overall configuration of blood pressure pulse wave inspection device FIG. 1 is a diagram showing the overall configuration of a blood pressure pulse wave inspection device 1 to which the heartbeat waveform extraction device and heartbeat waveform extraction method of the present invention are applied.

[0018] In FIG. 1, the main body 1a of the blood pressure pulse wave inspection device 1 is provided with an arithmetic processing unit 10, an input unit 70, a display unit 80, a printing unit 91, a memory unit 92, an audio output unit 93, a blood pressure pulse wave measuring unit 30, a heart sound measuring unit 40, an electrocardiogram measuring unit 50, and a pulse wave measuring unit 60.

[0019] The blood pressure pulse wave measurement unit 30 has an upper arm measurement control unit 31 and a lower limb measurement control unit 32. A right upper arm cuff 21R and a left upper arm cuff 21L are connected to the upper arm measurement control unit 31 via hoses 21h, and a right ankle cuff 22R and a left ankle cuff 22L are connected to the lower limb measurement control unit 32 via hoses 22h.

[0020] A heart sound microphone 23 is connected to the heart sound measurement unit 40. A four limb electrocardiogram electrode unit 24a and a chest electrocardiogram electrode unit 24b are connected to the electrocardiogram measurement unit 50. Amorphous pulse wave sensors 25a and 25b are connected to the pulse wave measurement unit 60.

[0021] The arithmetic processing unit 10 is a computer having a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), various interfaces, etc. The arithmetic processing unit 10 performs arithmetic processing for determining cardiac disease, which will be described below, by executing a processing program stored in the ROM on the CPU. In other words, the arithmetic processing unit 10 has a function for determining cardiac disease. The arithmetic processing unit 10 also has a function for extracting a heartbeat waveform used to determine cardiac disease.

[0022] In addition, the calculation processing unit 10 controls the upper arm measurement control unit 31, the lower limb measurement control unit 32, the heart sound measurement unit 40, the electrocardiogram measurement unit 50, and the pulse wave measurement unit 60 (hereinafter referred to as "each biological information measurement unit"), which measure various types of biological information.

[0023] The arithmetic processing unit 10 also receives biological information supplied from each biological information measurement unit. When the received biological information needs to be displayed on a screen, it edits or converts it into display data and outputs it to the display unit 80, and when it needs to be printed on a report form, it edits or converts it into print data and outputs it to the printing unit 91. The arithmetic processing unit 10 also stores the received biological information in the storage unit 92 and reads out the stored biological information as appropriate.

[0024] The calculation processing unit 10 also performs waveform analysis of the biological information received from each biological information measurement unit. In the waveform analysis, characteristic parts (dividing points) in the waveform are detected. Examples of characteristic parts include the start of the second heart sound, the rising edge of the pulse wave at the upper arm, the rising edge of the pulse wave at the ankle, and the notch of the pulse wave at the upper arm.

[0025] The arithmetic processing unit 10 calculates the degree of arteriosclerosis based on the analysis result and the value (for example, blood pressure) indicated by the received biological information.

[0026] In addition, the calculation processing unit 10 receives inputs and instructions from the input unit 70 through user operations, and in accordance with the received contents, performs settings related to the functions of each biometric information measurement unit, display unit 80, printing unit 91, memory unit 92 and audio output unit 93, and controls the start and stop of each operation.

[0027] The display unit 80 is a display device having a display screen such as an LCD (Liquid Crystal Display), and displays on the screen the biological information, analysis results, arteriosclerosis degree, etc. input from the arithmetic processing unit 10 as display data.

[0028] The printing unit 91 has as its main components a paper feed mechanism, a printing head, etc., and prints on paper the biological information, analysis results, and arteriosclerosis degree input as printing data from the arithmetic processing unit 10.

[0029] The storage unit 92 is configured with a hard disk drive, a writable optical disk drive, a nonvolatile memory, etc., and is capable of storing information from the calculation processing unit 10. The storage unit 92 also records biological information measured by each biological information measurement unit, that is, an electrocardiogram, a pulse wave, and heart sounds.

[0030] The audio output unit 93 has a speaker or the like as a main component, and outputs a guidance voice, an alert sound, or the like in accordance with the guidance data or an alert sound output instruction signal input from the calculation processing unit 10.

[0031] The input unit 70 is composed of a keyboard, a mouse, buttons, a touch panel, etc., and receives inputs and instructions from the user's operations and sends them to the arithmetic processing unit 10.

[0032] Pulse wave measuring unit 60 supplies the subject's pulse wave signals detected by amorphous pulse wave sensors 25a, 25b appropriately attached to the subject to calculation processing unit 10. This allows measurement and analysis of the pulse wave. Note that one of amorphous pulse wave sensors 25a, 25b is attached, for example, to the subject's carotid artery, and the other is attached, for example, to the subject's femoral artery or knee.

[0033] In this embodiment, the blood pressure pulse wave measuring unit 30 is configured by providing an upper limb measurement control unit 31 and a lower limb measurement control unit 32 independently, but the upper limb measurement control unit 31 and the lower limb measurement control unit 32 may be integrated together. For measuring blood pressure pulse waves by the blood pressure pulse wave measuring unit 30 having the upper limb measurement control unit 31 and the lower limb measurement control unit 32, known technology such as that described in Patent Document 2 may be used, and therefore detailed description thereof will be omitted here.

[0034] The electrocardiogram measurement unit 50 supplies electrocardiogram signals detected by the four limb electrocardiogram electrodes 24a and the chest electrocardiogram electrodes 24b attached to the subject to the arithmetic processing unit 10. This allows electrocardiogram measurement and analysis. The four limb electrocardiogram electrodes 24a typically consist of four electrocardiogram electrodes attached to the right wrist, left wrist, right ankle, and left ankle, respectively. The electrocardiogram electrodes for both ankles are preferably configured so that their attachment to both ankles is not obstructed by the right ankle cuff 22R and the left ankle cuff 22L. The chest electrocardiogram electrode unit 25b typically consists of six electrocardiogram electrodes attached to six locations on the chest.

[0035] The heart sound measuring unit 40 supplies a heart sound signal detected by the heart sound microphone 23 attached to the subject to the calculation processing unit 10. In this way, the heart sounds are measured and analyzed.

[0036] <2> Determining heart disease according to this embodiment As described above, the arithmetic processing unit 10 of this embodiment has the function of diagnosing cardiac disease and the function of extracting a cardiac waveform used for diagnosing cardiac disease. In practice, the arithmetic processing unit 10 has a cardiac disease diagnosing unit 110 and a cardiac waveform extracting unit 120, as shown in FIG.

[0037] The cardiac disease determining section 110 includes a systolic noise area calculating section 111, an IUT (Initial Upstroke Time) calculating section 112, and a determining section 113.

[0038] The systolic noise area calculation unit 111 calculates the area of ​​the systolic noise in the heart sounds measured by the heart sound measurement unit 40. The IUT calculation unit 112 inputs the pulse wave (blood pressure pulse wave) measured by the blood pressure pulse wave measurement unit 30, and calculates the IUT, which is an index representing the degree of blunting of the rising edge of the pulse wave. The determination unit 113 determines whether or not the patient has a heart disease based on the area of ​​the systolic noise calculated by the systolic noise area calculation unit 111 and the IUT calculated by the IUT calculation unit 112.

[0039] Here, a brief explanation will be given of the systolic murmur, the systolic murmur area, and the IUT.

[0040] FIG. 3 is a diagram used to explain systolic murmurs. FIG. 3 shows an electrocardiogram, heart sounds, and heart murmurs. The time when the peak of the R wave in the electrocardiogram appears is roughly the same as the start of the first heart sound, and the time when the end of the T wave in the electrocardiogram is roughly the same as the start of the second heart sound. The systole (ventricular systole) can be said to be the period from the peak of the R wave to the end of the T wave, or the period from the start of the first sound to the start of the second sound. The systolic murmur is a noise contained in the heart sounds during the systole (ventricular systole). In other words, the systolic murmur is the heart sounds during the systole (ventricular systole) excluding the first and second sounds.

[0041] 4 is a diagram illustrating the area of ​​the systolic murmur calculated by the systolic murmur area calculation unit 111. As can be seen from the figure, the systolic murmur area calculation unit 111 calculates the area surrounded by the envelope of the amplitude of the systolic murmur. Specifically, the systolic murmur area calculation unit 111 detects the first and second sounds from the heart sounds, determines the heart sound between them as the systolic murmur, and calculates the area of ​​the envelope of its amplitude.

[0042] Fig. 5 is a diagram illustrating the IUT calculated by the IUT calculation unit 112. As shown in Fig. 5, the IUT is the time it takes for a tangent drawn to the ascending limb at the beginning of the rise of the pulse wave to reach its wave height. Therefore, it can be said that the larger the IUT, the slower the rise of the pulse wave.

[0043] 6 is a flowchart showing the procedure of the determination process performed by the determination unit 113. When the determination unit 113 starts the process, it determines in step S11 whether the area of ​​the systolic murmur is equal to or greater than a predetermined threshold A1. If the determination unit 113 determines that the area of ​​the systolic murmur is equal to or greater than the predetermined threshold A1, it proceeds to step S12 and determines that AS is present (i.e., the subject has aortic stenosis).

[0044] On the other hand, if the determination unit 113 determines that the area of ​​the systolic murmur is less than the predetermined threshold A1, the process proceeds to step S13. In step S13, the determination unit 113 determines whether the area of ​​the systolic murmur is equal to or greater than a predetermined threshold A2. Here, the relationship between the thresholds A1 and A2 is A1>A2.

[0045] If the determining unit 113 determines that the area of ​​the systolic murmur is less than the predetermined threshold A2, the process proceeds to step S15, and determines that there is no AS (that is, the subject does not have aortic stenosis).

[0046] On the other hand, if the determination unit 113 determines that the area of ​​the systolic murmur is equal to or greater than the predetermined threshold A2, the process proceeds to step S14. In step S14, the determination unit 113 determines whether the IUT is equal to or greater than the predetermined threshold B1. If the determination unit 113 determines that the IUT is equal to or greater than the predetermined threshold B1, the process proceeds to step S12, and determines that AS is present (i.e., the subject has aortic stenosis).

[0047] In this way, the judgment unit 113 judges that AS is present when the area of ​​the systolic murmur is very large (i.e., when the area is equal to the threshold A1), and judges that AS is not present when the area of ​​the systolic murmur is very small (i.e., when the area is less than the threshold A2).

[0048] On the other hand, when the area of ​​the systolic noise is medium, the judgment unit 113 refers to the value of IUT (i.e., refers to the degree of blunting of the rise of the pulse wave), and determines that AS is present if the value of IUT is equal to or greater than threshold B1 (i.e., if the degree of blunting of the rise of the pulse wave is large), and determines that AS is not present if the value of IUT is less than threshold B1 (i.e., if the degree of blunting of the rise of the pulse wave is small).

[0049] 7 is a diagram showing the relationship between the threshold determination by the determination unit 113 and patients with aortic valve stenosis. In the diagram, a black circle indicates an AS patient, and a circle indicates a non-AS patient. If a positive result is obtained in step S11, patients with values ​​equal to or greater than the threshold A1 in the diagram are determined to be AS patients. In other words, patients in the region [1]+[2] in the diagram are determined to be AS patients.

[0050] If a negative result is obtained in step S11 and a negative result is obtained in step S13, patients whose scores are below threshold A1 and below threshold A2 in the figure are determined to be non-AS patients. In other words, patients in area [4] in the figure are determined to be non-AS patients.

[0051] If a negative result is obtained in step S11, a positive result is obtained in step S13, and a positive result is obtained in step S14, patients whose scores are less than threshold A1, equal to or greater than threshold A2, and equal to or greater than threshold B1 in the figure are determined to be AS patients. In other words, patients in area [3] in the figure are determined to be AS patients.

[0052] In this way, by using not only the area of ​​the systolic murmur but also the degree of blunting of the pulse wave rise as an index for determining aortic stenosis, it is possible to more accurately determine whether or not aortic stenosis is present compared to when aortic stenosis is determined based solely on the area of ​​the systolic murmur. In other words, it is possible to reduce erroneous determinations of the presence or absence of aortic stenosis compared to when determination is based solely on the area of ​​the systolic murmur.

[0053] In other words, the cardiac disease determination unit 110 includes a systolic noise area calculation unit 111 that calculates the area of ​​the systolic noise in the heart sound, an IUT calculation unit 112 that calculates the IUT, which is an index that indicates the degree of slowing of the rise of the pulse wave, and a determination unit 113 that determines whether or not there is aortic stenosis based on the systolic noise area and the IUT, so that cardiac diseases such as aortic stenosis can be examined without having to rely heavily on the judgment of medical professionals such as doctors.

[0054] <3> Extraction of heartbeat waveform according to this embodiment 2, the configuration of the heartbeat waveform extraction unit 120 will be described. The heartbeat waveform extraction unit 120 extracts a heartbeat waveform to be determined by the cardiac disease determination unit 110 from the electrocardiogram, pulse wave, and heart sounds stored in the storage unit 92, and outputs the extracted heartbeat waveform to the cardiac disease determination unit 110.

[0055] The heartbeat waveform extracting unit 120 includes a first excluded heartbeat evaluating unit 121, a second excluded heartbeat evaluating unit 122, a third excluded heartbeat evaluating unit 123, and an extracting unit .

[0056] The first excluded heartbeat evaluation unit 121 obtains an evaluation result that excludes heartbeats in which premature contractions appear in the electrocardiogram. The first excluded heartbeat evaluation unit 121 also obtains an evaluation result that excludes heartbeats whose QT interval values ​​in the electrocardiogram differ from the median QT interval by a predetermined value or more. The first excluded heartbeat evaluation unit 121 also obtains an evaluation result that excludes the first heartbeat and the last heartbeat in the recorded waveform.

[0057] The second excluded heartbeat evaluation unit 122 obtains an evaluation result in which heartbeats whose pulse wave rise is dulled by a degree that differs from the median by a predetermined value or more are to be excluded. In this embodiment, IUT (Initial Upstroke Time) is calculated as an index that indicates how dull the pulse wave rise is (which can also be said to indicate sleeping). Specifically, the degree to which the rise is dulled can be expressed by a slope (gradient). For example, when the angle with the time axis is 0, the slope (gradient) is 0, and the larger the angle with the time axis, the larger the slope (gradient). Therefore, the duller the rise of the pulse wave, the smaller the slope (gradient) and the larger the IUT. The second excluded heartbeat evaluation unit 122 obtains an evaluation result in which heartbeats whose IUT differs from the median by a predetermined value or more are to be excluded.

[0058] The third excluded heartbeat evaluation unit 123 evaluates the excluded heartbeats based on the baseline stability of the heart sounds.

[0059] The extraction unit 124 receives the evaluation results obtained by the first excluded heartbeat evaluation unit 121, the second excluded heartbeat evaluation unit 122, and the third excluded heartbeat evaluation unit 123. Based on these evaluation results, the extraction unit 123 extracts heartbeat waveforms of a common period from the electrocardiogram, pulse wave, and heart sounds stored in the storage unit 92.

[0060] In this embodiment, the extraction unit 124 extracts an electrocardiogram, pulse wave, and heart sound for one common heartbeat, and outputs the electrocardiogram and heart sound to the systolic noise area calculation unit 111 and the pulse wave to the IUT calculation unit 112.

[0061] Next, the operation of the cardiac waveform extraction section 120 will be described with reference to FIG.

[0062] First, in step S21, the heartbeat waveform extraction unit 120 reads out the first 20 heartbeats from the start of recording as candidates for extraction. Specifically, the first exclusion heartbeat evaluation unit 121 reads out an electrocardiogram for 20 heartbeats, the second exclusion heartbeat evaluation unit 122 reads out a pulse wave for 20 heartbeats, and the third exclusion heartbeat evaluation unit 123 reads out heart sounds for 20 heartbeats. Here, the electrocardiogram, pulse wave, and heart sounds read out by the first exclusion heartbeat evaluation unit 121, the second exclusion heartbeat evaluation unit 122, and the third exclusion heartbeat evaluation unit 123 are electrocardiograms, pulse waves, and heart sounds for 20 heartbeats over a common period. Of course, the number of heartbeats read out does not have to be 20 heartbeats. However, if the number of heart rates read out is too small, it may not be possible to extract heart rates suitable for assessment by the cardiac disease assessment unit 110, and if it is too large, the amount of calculation required for assessment by the assessment units 121, 122, and 123 will increase, so it is preferable that the number be around 10 to 30 heart rates, for example.

[0063] In step S22, the first excluded heartbeat evaluation unit 121 detects the first heartbeat, the final heartbeat, and the premature systolic heartbeat, and outputs these heartbeats as excluded heartbeats to the extraction unit 124. FIG. 9 is a diagram showing the first heartbeat, the final heartbeat, and the premature systolic heartbeat to be excluded. The reason for excluding the first heartbeat and the final heartbeat is that, in the recorded waveform, the start point of the first heartbeat and the end point of the final heartbeat may be cut off midway through the heartbeat. In addition, the reason for excluding the premature systolic heartbeat (arrhythmia) is that the electrocardiogram and pulse wave are locally disturbed at the position of the premature systolic heartbeat (arrhythmia), making them undesirable heartbeats to be used by the cardiac disease determination unit 110.

[0064] In step S23, the first excluded heartbeat evaluation unit 121 detects the QT interval of each heartbeat and calculates its median (which may also be called the average value) (i.e., calculates the median QT interval of 20 heartbeats). Then, the first excluded heartbeat evaluation unit 121 evaluates each heartbeat according to how far its QT interval is from the median. In the present embodiment, the first excluded heartbeat evaluation unit 121 evaluates a heartbeat whose QT interval value is within ±5% of the median as a good heartbeat (◯ heartbeat), a heartbeat whose QT interval value is within ±10% of the median as a acceptable heartbeat (△ heartbeat), and a heartbeat whose QT interval value exceeds ±10% from the median as an unacceptable heartbeat (× heartbeat).

[0065] Here, since the start position of the first heart sound and the peak position of the R wave of the electrocardiogram are approximately the same, the systolic noise area calculation unit 111 detects the first heart sound based on the peak position of the R wave. The systolic noise area calculation unit 111 also detects the second heart sound based on the end position of the T wave. In order to measure the systolic murmur between the first and second heart sounds, it is preferable to accurately detect the first and second heart sounds.

[0066] Incidentally, since a phonocardiogram contains a lot of noise, detecting the first and second sounds directly from the phonocardiogram may result in a decrease in detection accuracy. Therefore, the systolic noise area calculation unit 111 detects the position of the first sound based on the R wave and the position of the second sound based on the position of the T wave.

[0067] For this reason, if the position of the T wave is erroneously detected, the position of the second heart sound will also be erroneously detected, which may result in an erroneous area of ​​the systolic murmur calculated by the systolic noise area calculation unit 111. In consideration of this, in this embodiment, the first excluded heartbeat evaluation unit 121 excludes heartbeats other than those for which the T wave has been correctly detected, based on the QT interval. The evaluation by the first excluded heartbeat evaluation unit 121 is based on the idea that QT intervals rarely differ greatly among heartbeats, and that large differences in QT intervals indicate a high possibility that the T wave has been erroneously detected.

[0068] FIG. 10 is a diagram showing the state of evaluation performed by the first excluded heartbeat evaluation unit 121. N6 to N16 shown in the diagram represent heartbeat numbers, and the numerical values ​​shown below them represent the QT intervals of each heartbeat. In the example shown in the diagram, the heartbeat N11 is evaluated as an impossible heartbeat (x heartbeat), and the heartbeat N12 is evaluated as a possible heartbeat (Δ heartbeat). In the example of FIG. 10, the heartbeat N12 is a heartbeat for which the measurement of the end point of the T wave was incorrect. The first excluded heartbeat evaluation unit 121 can lower the evaluation of heartbeats whose QT intervals are extremely different from the QT intervals of other heartbeats, thereby lowering the evaluation of heartbeats for which there is a high possibility that the end point of the T wave has been measured incorrectly.

[0069] In step S24, the second excluded heartbeat evaluation unit 122 calculates the index of onset of pulse wave (IUT) of each heartbeat and calculates its median (which may also be called the average value) (i.e., calculates the median IUT of 20 heartbeats). Then, the second excluded heartbeat evaluation unit 122 evaluates each heartbeat according to how far the IUT of each heartbeat is from the median. In the case of this embodiment, the second excluded heartbeat evaluation unit 122 evaluates a heartbeat whose IUT value is within ±5% of the median as a good heartbeat (◯ heartbeat), evaluates a heartbeat whose IUT value is within ±10% of the median as an acceptable heartbeat (△ heartbeat), and evaluates a heartbeat whose IUT value exceeds ±10% from the median as an unacceptable heartbeat (× heartbeat).

[0070] Fig. 11 is a diagram showing the state of evaluation performed by the second excluded heartbeat evaluation unit 122. In the example of Fig. 11, the second excluded heartbeat evaluation unit 122 evaluates, among the pulse waves of each heartbeat, a heartbeat with an IUT of "140" as an impossible heartbeat (x heartbeat), and evaluates a heartbeat with an IUT of "170" as a possible heartbeat (△ heartbeat).

[0071] In step S25, the third excluded heartbeat evaluation unit 123 calculates the baseline stability of the heart sounds for each heartbeat and selects the top five heartbeats with the highest baseline stability. Various methods can be used to calculate the baseline stability of heart sounds. A preferred example of how to calculate the baseline stability of heart sounds will be described below.

[0072] First, as shown in FIG. 12, the third excluded heartbeat evaluation unit 123 defines a predetermined section (atrial systole) before the QRS wave of the target heartbeat as the baseline and measures the variance of the heart sound baseline (this is called variance 1). Incidentally, FIG. 12A is an electrocardiogram, and FIG. 12B is a phonocardiogram. Next, the third excluded heartbeat evaluation unit 123 measures the variance of a predetermined section before the QRS wave of the next heartbeat (this is called variance 2). Next, the third excluded heartbeat evaluation unit 123 calculates the sum of variance 1 and variance 2 (variance 1 + variance 2) as the baseline stability of the target heartbeat. In FIG. 12B, the numerical value assigned to each heartbeat is the baseline stability of each heartbeat calculated in this manner. It can be said that the smaller this numerical value, the smaller the variance and the higher the baseline stability of the heartbeat.

[0073] A heartbeat with low baseline stability is one that is likely to have periodic noise, such as respiratory sounds, superimposed thereon. The cardiac disease determining unit 110 preferably performs determination on heartbeats that are not contaminated with periodic noise. Therefore, in this embodiment, the top five heartbeats with the highest baseline stability are selected as candidates. In the example of FIG. 12B, the five heartbeats marked with a double circle and a circle are selected as candidates.

[0074] In step S26, the extraction unit 124 extracts heartbeat waveforms (i.e., electrocardiogram, pulse wave, and heart sounds) for the common period based on the evaluation results obtained by the first excluded heartbeat evaluation unit 121, the second excluded heartbeat evaluation unit 122, and the third excluded heartbeat evaluation unit 123, and outputs the extracted waveforms to the cardiac disease determination unit 110. In this embodiment, the extraction unit 124 extracts a representative heartbeat from the top five heartbeats selected in step S25, taking into account the classifications made in steps S23 and S24.

[0075] For example, the extraction unit 124 assigns priority points as shown in FIG. 13 for the classification in steps S23 and S24, and extracts a combination of a QT interval and an IUT with a high priority point as a representative heartbeat.

[0076] The processing order of steps S22 to S25 may be reversed, or steps may be performed in parallel.

[0077] Using the example of FIG. 14, the extraction of representative heartbeats by the extraction unit 124 will be described. Heartbeats N12, N13, N14, N15, and N16 are selected as the top five heartbeats with the highest baseline stability of heart sounds. Of these five heartbeats, a combination of the QT interval of the electrocardiogram and the IUT of the pulse wave, which has the highest priority point, is selected. In the example of FIG. 14, the priority point of the heartbeats N14, N15, and N16 is "6," so one of these heartbeats is extracted as the representative heartbeat. Of the heartbeats N14, N15, and N16, the extraction unit 124 extracts, for example, the heartbeat N16, which has the highest baseline stability, as the representative heartbeat. Specifically, the extraction unit 124 reads out the electrocardiogram, pulse wave, and heart sounds of the heartbeat N16 from the storage unit 92 and outputs them to the cardiac disease determination unit 110.

[0078] <4> summary As described above, according to this embodiment, there are provided a heartbeat waveform acquisition unit (electrocardiogram measurement unit 50, blood pressure pulse wave measurement unit 30, heartbeat measurement unit 40) that acquires a heartbeat waveform including an electrocardiogram, pulse wave, and heart sounds of the subject, a memory unit 92 that stores the heartbeat waveform, and a heartbeat waveform extraction unit 120 that reads out multiple heartbeats (e.g., 20 heartbeats) from the heartbeat waveforms stored in the memory unit 92 and comprehensively evaluates each heartbeat based on the electrocardiogram, pulse wave, and heart sounds included in the multiple heartbeats to extract a representative heartbeat (e.g., one heartbeat) suitable for testing for heart valve diseases from the multiple heartbeats and outputs the electrocardiogram, pulse wave, and heart sounds included in the representative heartbeat to an apparatus for testing for heart valve diseases (heart disease determination unit 110).By providing these units, it is possible to extract a heartbeat waveform suitable for testing for heart valve diseases such as aortic valve stenosis, thereby improving the testing accuracy of the apparatus for testing for heart valve diseases.

[0079] Here, for example, diagnosing aortic stenosis requires information (or signals) from an electrocardiogram, pulse waves, and heart sounds. It is important to select and analyze heartbeats in which all of these are stable. While prior art exists for independently assessing the stability of each piece of information, no method has been developed for extracting a representative heartbeat (one heartbeat in the embodiments) by comprehensively evaluating the stability of the three pieces of information. In the above-described embodiment, since the electrocardiogram, pulse waves, and heart sounds are interrelated, it is preferable to extract and examine heartbeats in the same phase rather than diagnosing each piece of information separately. Therefore, the representative beats in the same phase are extracted by comprehensively evaluating each heartbeat based on the electrocardiogram, pulse waves, and heart sounds. Incidentally, if different heartbeats are extracted from the electrocardiogram, pulse waves, and heart sounds, heartbeat synchronization will not be ensured, which may reduce the reliability of diagnosing aortic stenosis.

[0080] Furthermore, according to this embodiment, the heartbeat waveform extraction unit 120 includes a first excluded heartbeat evaluation unit 121 that evaluates, as targets for exclusion, premature contraction heartbeats in an electrocardiogram and heartbeats whose QT interval values ​​in an electrocardiogram differ from the median QT interval by a predetermined value or more, a second excluded heartbeat evaluation unit 122 that evaluates, as targets for exclusion, heartbeats whose pulse wave has a dull rising edge that differs from the median by a predetermined value or more, a third excluded heartbeat evaluation unit 123 that evaluates the excluded heartbeats based on the baseline stability of the heart sounds, and an extraction unit 124 that extracts representative heartbeats based on the evaluation results obtained by the first excluded heartbeat evaluation unit 121, the second excluded heartbeat evaluation unit 122, and the third excluded heartbeat evaluation unit 123. This makes it possible to extract a heartbeat waveform that is more suitable for a device (heart disease determination unit 110) that performs an examination for aortic stenosis.

[0081] The above-described embodiment has been made based on the following considerations.

[0082] In patients with AS, systolic murmurs are observed at almost every heartbeat. Therefore, if testing is based on systolic murmurs, it seems possible to test at any heartbeat.

[0083] Premature contraction heartbeats (arrhythmia) are excluded because electrocardiograms and pulse waves cannot be evaluated (processing in the first excluded heartbeat evaluation unit 121).

[0084] The first heartbeat and the final heartbeat are excluded because the start or end point of the waveform may be cut off (processing in the first excluded heartbeat evaluation unit 121).

[0085] There are heartbeats that may cause an error in the measurement of the T wave end point of an electrocardiogram, and such heartbeats are excluded (processing by the first excluded heartbeat evaluation unit 121). This is because an error in the measurement of the T wave end point can have a negative effect on the measurement of the division points of a phonocardiogram. Specifically, if the position of the T wave is incorrect, the position of the second heart sound will be incorrectly detected, and as a result, the measurement of the systolic murmur will also be incorrect. Therefore, heartbeats that cause an error in detecting the T wave are excluded.

[0086] If periodic respiratory noise is mixed into the heart sounds, the diagnostic device may mistakenly determine that the respiratory noise is a systolic noise, which reduces the accuracy of the diagnosis based on the systolic noise. Therefore, heartbeats mixed with respiratory noise are excluded (processing by the third excluded heartbeat evaluation unit 123).

[0087] The above-described embodiments are merely examples of specific embodiments of the present invention, and the technical scope of the present invention should not be construed as being limited by these embodiments. In other words, the present invention can be embodied in various forms without departing from the gist or main characteristics thereof.

[0088] In the above-described embodiment, the case where IUT is used as an index representing the degree of blunting of the rising edge of the pulse wave has been described, but the present invention is not limited to this, and another index may be used as an index representing the degree of blunting of the rising edge of the pulse wave.

[0089] In the above-described embodiment, the first excluded heartbeat evaluation unit 121 evaluates, as targets for exclusion, premature contraction heartbeats in an electrocardiogram and heartbeats whose QT interval values ​​in an electrocardiogram differ from the median of the QT interval by a predetermined value or more, and the second excluded heartbeat evaluation unit 122 evaluates, as targets for exclusion, heartbeats whose pulse wave has a slower rising edge that differs from the median by a predetermined value or more. However, the first and second excluded heartbeat evaluation units 121 and 122 may perform evaluation using other basic statistical values ​​such as the mean value or the mode, rather than the median.

[0090] In the above-described embodiment, the first excluded heartbeat evaluation unit 121 evaluates, as candidates for exclusion, premature contraction heartbeats in an electrocardiogram and heartbeats whose QT interval values ​​in an electrocardiogram differ from a basic statistical value (e.g., the median) of QT intervals by a predetermined value or more, the second excluded heartbeat evaluation unit 122 evaluates, as candidates for exclusion, heartbeats whose pulse wave rise is dulled by a predetermined value or more from a basic statistical value (e.g., the median), and the third excluded heartbeat evaluation unit 123 performs evaluation based on baseline stability of heart sounds. However, the present invention is not limited to this. In short, it is sufficient that the first excluded heartbeat evaluation unit 121 evaluates, as candidates for exclusion, heartbeats containing an irregular electrocardiogram, the second excluded heartbeat evaluation unit 122 evaluates, as candidates for exclusion, heartbeats containing an irregular pulse wave, and the third excluded heartbeat evaluation unit 123 evaluates, as candidates for exclusion, heartbeats containing an irregular heart sound.

[0091] In other words, the evaluation criteria by the first excluded heartbeat evaluation unit 121, the second excluded heartbeat evaluation unit 122, and the third excluded heartbeat evaluation unit 123 are not limited to those explained in steps S23, S24, and S25 of the above-mentioned embodiment. The point is that it is sufficient to evaluate the suitability of each of the electrocardiogram, pulse wave, and heart sound for testing for heart valve diseases, and to extract a representative heartbeat by combining the evaluations.

[0092] In the above embodiment, a case where one representative heartbeat is extracted from a plurality of candidate heartbeats has been described, but this is not limiting, and for example, two representative heartbeats may be extracted. In short, it is sufficient to exclude heartbeats that are not suitable for testing for heart valve disease from the plurality of candidate heartbeats and output them to the testing device.

[0093] In the above-described embodiment, the cardiac disease assessment unit 110 is described as the device that outputs the extracted representative heartbeats. However, the output device is not limited to this. The output device may be various devices for examining cardiac valve diseases based on an electrocardiogram, a pulse wave, and a heart sound. That is, in the above-described embodiment, the output device is the cardiac disease assessment unit 110 that determines whether or not there is aortic valve stenosis. However, the output device may be a device that examines other cardiac diseases (cardiac valve diseases) such as mitral regurgitation (MR). In this case, the evaluation criteria used by the first excluded heartbeat evaluation unit 121, the second excluded heartbeat evaluation unit 122, and the third excluded heartbeat evaluation unit 123 in the above-described embodiment may be appropriately changed, or other indicators may be introduced.

[0094] In the above-described embodiment, the heartbeat waveform extraction device and heartbeat waveform extraction method of the present invention are described as being embodied in a blood pressure pulse wave inspection device 1, but the heartbeat waveform extraction device and heartbeat waveform extraction method of the present invention are not limited to this, and may be embodied in a device (such as a personal computer) separate from the blood pressure pulse wave inspection device.

[0095] In essence, the heartbeat waveform extraction device of the present invention may include a heartbeat waveform acquisition unit that acquires a heartbeat waveform including an electrocardiogram, pulse wave, and heart sounds of a subject, a memory unit that stores the heartbeat waveform, and a heartbeat waveform extraction unit 120 that reads multiple heartbeats from the heartbeat waveforms stored in the memory unit, comprehensively evaluates each heartbeat based on the electrocardiogram, pulse wave, and heart sounds contained in the multiple heartbeats, thereby extracting a representative heartbeat from the multiple heartbeats suitable for testing for heart valve disease, and outputs the electrocardiogram, pulse wave, and heart sounds contained in the representative heartbeat to a device that tests for heart valve disease. Here, the heartbeat waveform acquisition unit may be the blood pressure pulse wave measurement unit 30, the heartbeat sound measurement unit 40, and the electrocardiogram measurement unit 50 as in the above-described embodiment, or it may be an input unit such as an interface that inputs information about the pulse wave, heart sounds, and electrocardiogram.

[0096] Furthermore, the storage unit that stores the heartbeat waveform may be an external server, etc. Therefore, the present invention can also be embodied in the form of a system including a heartbeat waveform acquisition unit that acquires a heartbeat waveform including an electrocardiogram, a pulse wave, and heart sounds of a subject, a storage unit that stores the heartbeat waveform, and a heartbeat waveform extraction unit that reads multiple heartbeats from the heartbeat waveform stored in the storage unit and comprehensively evaluates each heartbeat based on the electrocardiogram, pulse wave, and heart sounds included in the multiple heartbeats to extract a representative beat from the multiple heartbeats that is suitable for testing for heart valve disease, and outputs the electrocardiogram, pulse wave, and heart sounds included in the representative beat to an apparatus that tests for heart valve disease. [Industrial Applicability]

[0097] The present invention is widely applicable to a cardiac waveform extraction device and a cardiac waveform extraction method for extracting cardiac waveforms to be supplied to devices for examining cardiac diseases such as aortic valve stenosis. [Explanation of symbols]

[0098] 1. Blood pressure pulse wave testing device 10. Processing unit 30 Blood pressure pulse wave measurement unit 40 Heart sound measurement unit 50 Electrocardiogram measurement unit 92 Memory section 110 Heart Disease Assessment Department 111 Systolic noise area calculation unit 112 IUT calculation section 113 Judgment section 120 Heart Rate Waveform Extraction Unit 121 First excluded heartbeat evaluation unit 122 Second excluded heartbeat evaluation unit 123 Third Exclusion Heart Rate Evaluation Unit 124 Extraction part

Claims

1. a heartbeat waveform acquisition unit for acquiring a heartbeat waveform including an electrocardiogram, a pulse wave, and a heart sound of a subject; a storage unit that stores the cardiac waveform; a heartbeat waveform extraction unit that reads out multiple heartbeats from the heartbeat waveforms stored in the storage unit, comprehensively evaluates each heartbeat based on the electrocardiogram, pulse wave, and heart sound contained in the multiple heartbeats, extracts a representative heartbeat from the multiple heartbeats in which the electrocardiogram, pulse wave, and heart sound are in the same phase, and outputs the electrocardiogram, pulse wave, and heart sound contained in the representative heartbeat to a device for examining heart valve diseases; A heartbeat waveform extraction device comprising:

2. the heartbeat waveform extraction unit performs evaluation based on at least a QT interval in an electrocardiogram, a degree of slowing of a rising edge in a pulse wave, and a baseline stability in a heart sound; The cardiac waveform extraction device according to claim 1 .

3. the heartbeat waveform extraction unit assigns priorities to the heartbeats based on a plurality of indices and comprehensively evaluates each heartbeat; The cardiac waveform extraction device according to claim 1 .

4. a device for examining the heart for valvular disease; The cardiac waveform extraction device according to claim 1 .

5. The heartbeat waveform extraction unit a first excluded heartbeat evaluation unit that evaluates a heartbeat including an irregular electrocardiogram as an object to be excluded; a second excluded heartbeat evaluation unit that evaluates heartbeats including irregular pulse waves as targets for exclusion; a third excluded heartbeat evaluation unit that evaluates heartbeats including irregular heart sounds as targets for exclusion; an extracting unit that extracts the representative heartbeat based on the evaluation results obtained by the first, second, and third excluded heartbeat evaluating units; Equipped with The cardiac waveform extraction device according to claim 1 .

6. the first excluded heartbeat evaluation unit evaluates, as targets for exclusion, a premature contraction heartbeat in an electrocardiogram and a heartbeat whose QT interval value in an electrocardiogram differs from a basic statistical value of the QT interval by a predetermined value or more; the second exclusion heartbeat evaluation unit evaluates, as an exclusion target, a heartbeat whose degree of slowing of the rising edge in the pulse wave differs from the basic statistical value by a predetermined value or more; the third excluded heartbeat evaluation unit performs evaluation based on baseline stability of heart sounds; The cardiac waveform extraction device according to claim 2 .

7. a heartbeat waveform acquisition unit for acquiring a heartbeat waveform including an electrocardiogram, a pulse wave, and a heart sound of a subject; a storage unit that stores the cardiac waveform; a heartbeat waveform extraction unit that reads out multiple heartbeats from the heartbeat waveforms stored in the storage unit, comprehensively evaluates each heartbeat based on the electrocardiogram, pulse wave, and heart sound contained in the multiple heartbeats, extracts a representative beat from the multiple heartbeats in which the electrocardiogram, pulse wave, and heart sound are in the same phase, and outputs the electrocardiogram, pulse wave, and heart sound contained in the representative beat to a device for examining heart valve diseases; A system comprising:

8. acquiring a cardiac waveform including an electrocardiogram, a pulse wave, and heart sounds of a subject; storing the cardiac waveform; a heartbeat waveform extraction step of reading out multiple heartbeats from the stored heartbeat waveforms, comprehensively evaluating each heartbeat based on the electrocardiogram, pulse wave, and heart sound contained in the multiple heartbeats, thereby extracting a representative heartbeat from the multiple heartbeats that is suitable for examining heart valve diseases and in which the electrocardiogram, pulse wave, and heart sound are in the same phase, and outputting the electrocardiogram, pulse wave, and heart sound contained in the representative heartbeat to a device for examining heart valve diseases; A method for extracting a heartbeat waveform, comprising:

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