Heart sound detection device and heart sound detection method

Abstract

To provide a heart sound detecting device and heart sound detecting method capable of suppressing a decrease in reliability of diagnosis due to false detection of I and II sounds in a phonocardiogram, particularly the false detection of the II sound.SOLUTION: A heart sound detecting device includes: an I sound / II sound detecting part for detecting a time point of an I sound in a phonocardiogram based on a peak time of an R wave detected by an electrocardiogram analysis part, and detecting a time point of an II sound in the phonocardiogram based on a T wave termination time; a reference QT interval calculation part for calculating a QT interval based on the T wave termination time and a Q wave start time detected by the electrocardiogram analysis part, and further calculating a reference QT interval from the QT interval; and an invalidity determination part for detecting a heart rate whose QT interval is deviated by a prescribed value or more compared with the reference QT interval and invalidating a detection result of the II sound to be detected based on the T wave termination time of the heart rate.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a heart sound detection device and a heart sound detection method for detecting the first and second sounds from heart sounds using an electrocardiogram. [Background technology]

[0002] Heart sounds include a first heart sound due to the closure of the mitral and tricuspid valves, and a second heart sound due to the closure of the aortic valve.

[0003] The first and second sounds are sometimes used in devices for diagnosing heart valve disease. In a heart valve disease diagnosis device, the first and second sounds are first detected, and then heart valve disease is diagnosed based on the volume of the noise (systolic murmur) present between the first and second sounds. A device for diagnosing heart valve disease based on the systolic murmur is disclosed in, for example, Patent Document 1.

[0004] FIG. 1 is a diagram used to explain the first sound, second sound, and systolic murmur. FIG. 1 shows an electrocardiogram, heart sounds, and heart murmur. The peak of the R wave in the electrocardiogram and the start of the first sound in the heart sounds are approximately the same, and the end of the T wave in the electrocardiogram and the start of the second sound in the heart sounds are approximately the same. 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 end 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.

[0005] Incidentally, since a phonocardiogram contains a lot of noise, there is a risk that the detection accuracy will decrease if the first and second sounds are detected directly from the phonocardiogram. Therefore, as mentioned above, a method is generally adopted in which the first sound is detected from the peak of the R wave of the electrocardiogram and the second sound is detected from the end of the T wave. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-188512 Summary of the Invention [Problem to be solved by the invention]

[0007] However, if the first and second sounds are detected at the wrong locations, the reliability of the diagnosis may be reduced. However, it cannot be said that sufficient measures have been taken to address this issue.

[0008] The present invention has been made in consideration of the above points, and provides a heart sound detection device and a heart sound detection method that can suppress a decrease in diagnostic reliability due to erroneous detection of the first and second sounds in a phonocardiogram, particularly erroneous detection of the second sound. [Means for solving the problem]

[0009] One aspect of the heart sound detection device of the present invention is an acquisition unit for acquiring a phonocardiogram and an electrocardiogram of the subject; an electrocardiogram analysis unit that detects the peak time of the R wave, the end time of the T wave, and the start time of the Q wave of the electrocardiogram; a first sound / second sound detection unit that detects the time of first sound in the phonocardiogram based on the peak time of the R wave detected by the electrocardiogram analysis unit, and detects the time of second sound in the phonocardiogram based on the end time of the T wave; a reference QT interval calculation unit that calculates a QT interval based on the T wave end time and the Q wave start time detected by the electrocardiogram analysis unit, and further calculates a reference QT interval from the calculated QT interval; an invalidation determination unit that detects a heartbeat whose QT interval deviates by a predetermined value or more compared to the reference QT interval, and invalidates the detection result of the second sound detected based on the end time of the T wave of the heartbeat; Equipped with.

[0010] One aspect of the heart sound detection method of the present invention includes: obtaining a phonocardiogram and an electrocardiogram of the subject; detecting the peak time of the R wave, the end time of the T wave, and the start time of the Q wave of the electrocardiogram; detecting a time point of the first sound in the phonocardiogram based on the peak time point of the detected R wave and detecting a time point of the second sound in the phonocardiogram based on the end time point of the T wave; calculating a QT interval based on the detected T wave end time and Q wave start time, and further calculating a reference corrected QT interval from the QT interval; detecting a heartbeat whose QT interval deviates from the reference QT interval by a predetermined value or more, and invalidating the detection result of the second sound detected based on the end time of the T wave of the heartbeat; Includes: [Effects of the Invention]

[0011] According to the present invention, by invalidating the detection result of the second sound detected based on the end point of the T wave of a heartbeat whose QT interval deviates from the reference QT interval by a predetermined value or more, it is possible to suppress a decrease in the reliability of diagnosis due to erroneous detection of the second sound in a phonocardiogram. [Brief explanation of the drawings]

[0012] [Figure 1] Diagrams explaining the first and second sounds and systolic murmur [Figure 2] Figure showing an example of normal detection of T waves and R waves [Figure 3] An example of an electrocardiogram containing arrhythmia [Figure 4] An example of an electrocardiogram in which a T wave is mistakenly detected as an R wave. [Figure 5] FIG. 1 illustrates an example of T-wave nulling according to the present invention. [Figure 6] FIG. 1 is a diagram showing the overall configuration of a blood pressure pulse wave inspection device according to an embodiment. [Figure 7] FIG. 1 is a block diagram showing the main configuration of a heart sound detection device according to an embodiment. [Figure 8] 1 is a flowchart illustrating the operation of an embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0013] Before describing the embodiments, the background to the invention and the principles of the invention will be described.

[0014] The inventors of the present invention have considered invalidating erroneously detected R waves and T waves, since if the detection positions of R waves and T waves from an electrocardiogram are incorrect, the detection positions of the first and second sounds will also be incorrect.

[0015] First, a conventional method for nulling R waves will be described with reference to FIG. 2-4.

[0016] Figure 2 shows an example of T waves and R waves being detected correctly. Figure 3 shows an example of an electrocardiogram containing arrhythmia. Figure 4 shows an example of an electrocardiogram in which T waves have been mistakenly detected as R waves. By invalidating R waves with irregular RR intervals, it is possible to invalidate R waves due to arrhythmia (Figure 3) and R waves due to erroneous detection (Figure 4), as shown by the x in the figure.

[0017] As shown in the examples of Figures 3 and 4, a conventional method is to perform invalidation processing based on the R-R interval to invalidate inappropriate R waves and erroneously detected R waves.

[0018] On the other hand, with conventional invalidation processing based on the RR interval, if the start or peak of the T wave is mistakenly detected as the end of the T wave, it is not possible to invalidate it. As a result, the position of the second sound, which should be the end of the T wave, is mistakenly detected as the start or peak of the T wave, and if the position of the second sound is used to diagnose heart valve disease, the reliability of the diagnosis will be reduced.

[0019] The inventors of the present invention focused on this point and devised a method for identifying the end point of a T wave that has been erroneously detected and invalidating a second sound based on that end point of the T wave, resulting in the present invention. In the present invention, the detection result of the second sound detected based on the end point of the T wave of a heartbeat with an irregular QT interval is invalidated based on the QT interval. Specifically, a reference QT interval is calculated from the QT intervals of multiple heartbeats, a heartbeat whose QT interval deviates from the reference QT interval by a predetermined value or more is detected, and the detection result of the second sound detected based on the end point of the T wave of that heartbeat is invalidated.

[0020] This makes it possible to prevent a decrease in diagnostic reliability due to the false detection of the second sound in a phonocardiogram. Note that a decrease in diagnostic reliability due to the false detection of the first sound can be prevented by invalidating the R wave based on the conventional RR interval.

[0021] In addition, in this embodiment, when performing invalid processing based on the QT interval, a corrected QT interval (so-called QTc: QTc = QT interval / √RR interval) is calculated and used, where the QT interval is corrected by the heart rate. In this way, a corrected QT interval is used in which the QT variation caused by respiratory variation is suppressed by correction, so that the adverse effect of respiratory variation on invalid judgment can be reduced. The corrected QT interval is calculated using, for example, Fridericia's QT correction formula (QTc = QT interval / 3 The corrected QT interval may be calculated using the √RR interval. In essence, the corrected QT interval is the original QT interval corrected by the heart rate.

[0022] FIG. 5 shows an example of T wave nulling (or second sound nulling) according to the present invention. The waveform in the figure shows an electrocardiogram, with N1-N10 indicating heartbeats. The numbers written below N1-N10 indicate the corrected QT intervals at each heartbeat. In the example shown, the corrected QT intervals for heartbeats N3, N5, and N9 are nullified because they deviate by a predetermined value or more from the reference corrected QT interval.

[0023] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0024] <1> Overall configuration of blood pressure pulse wave inspection device FIG. 6 is a diagram showing the overall configuration of a blood pressure pulse wave inspection device 1 to which the heart sound detection device and heart sound detection method of the present invention are applied.

[0025] In Figure 6, 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.

[0026] 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.

[0027] 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.

[0028] 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 control unit 10 executes a control program stored in the ROM with the CPU, thereby performing arithmetic processing to realize the functions of the heart sound detection unit 11 and the valve disease determination unit 12 shown in Fig. 7 below.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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. Known technology may be used to measure blood pressure pulse waves using the blood pressure pulse wave measuring unit 30 having the upper limb measurement control unit 31 and the lower limb measurement control unit 32, so detailed description thereof will be omitted here.

[0041] 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.

[0042] The heart sound measurement 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.

[0043] <2> Heart sound detection process according to this embodiment The arithmetic processing unit 10 of this embodiment has the function of detecting characteristic points of heart sounds including the first and second sounds. In practice, it has the configuration shown in Fig. 7, which detects characteristic points of heart sounds including the first and second sounds, and furthermore, heart disease is diagnosed using the detected characteristic points. The arithmetic processing unit 10 has a heart sound detection unit 11 and a valve disease diagnosis unit 12.

[0044] The heart sound detector 11 includes an electrocardiogram analyzer 11a, an RR interval calculator 11b, a corrected QT interval calculator 11c, a reference corrected QT interval calculator 11d, an invalidity determiner 11e, and a first sound / second sound detector 11f.

[0045] The electrocardiogram analysis unit 11a receives an electrocardiogram stored in the storage unit 92 and performs electrocardiogram analysis to detect at least the peak time of the R wave, the end time of the T wave, and the start time of the Q wave of the electrocardiogram. Since the electrocardiogram analysis can be realized by known techniques, a detailed description thereof will be omitted here.

[0046] The R-R interval calculation unit 11b calculates the R-R interval and outputs the calculation result to the invalidation determination unit 11e. As described with reference to Figs. 3 and 4, the invalidation determination unit 11e performs invalidation processing based on the R-R interval, thereby invalidating inappropriate R waves and erroneously detected R waves.

[0047] The corrected QT interval calculation unit 11c calculates a corrected QT interval (so-called QTc) using the R wave, T wave, and Q wave obtained by the electrocardiogram analysis unit 11a. Specifically, the corrected QT interval calculation unit 11c calculates the corrected QT interval (QTc) by performing the calculation QTc=QT interval / √RR interval. For example, the corrected QT interval calculation unit 11c calculates the corrected QT interval (QTc) for each of the 10 heartbeats in FIG. 5.

[0048] The reference corrected QT interval calculation unit 11d calculates the median of the corrected QT intervals (QTc) for multiple heartbeats as the reference corrected QT interval. Note that the reference corrected QT interval calculated by the reference corrected QT interval calculation unit 11d is not limited to the median, and may be, for example, the average or mode of the corrected QT intervals (QTc) for multiple heartbeats. The calculated reference corrected QT interval is output to the invalidity determination unit 11e.

[0049] The invalidity determination unit 11e detects a heartbeat whose corrected QT interval deviates from the reference corrected QT interval by a predetermined value or more, and invalidates the end point of the T wave of that heartbeat. As a result, the detection of the second sound detected based on the end point of the T wave of that heartbeat is invalidated. For example, the invalidity determination unit 11e determines, among the 10 corrected QT intervals of FIG. 5, heartbeats whose corrected QT interval deviates from the median (reference corrected QT interval) by more than ±10% as heartbeats whose T wave end points are to be invalidated. In the example of FIG. 5, heartbeats N3, N5, and N9 are determined to be heartbeats whose T wave end points are to be invalidated.

[0050] The first and second sound detection unit 11f receives the heart sounds stored in the memory unit 92 and the R and T waves that have not been invalidated by the invalidation determination unit 11e as input, and detects the first and second sounds by taking the peak of the R wave as the starting point of the first sound and the end of the T wave as the starting point of the second sound, as described above with reference to FIG. 1.

[0051] The valve disease determination unit 12 identifies the position of the systolic murmur in the heart sounds using the positions of the first and second sounds detected by the first and second sound detection unit 11f, and determines the presence of a valve disease such as aortic stenosis based on characteristics such as the area and shape of the systolic murmur.

[0052] This prevents erroneous detection of the first and second sounds due to erroneous detection of the R and T waves, and as a result, reduces the deterioration of the reliability of the diagnosis made by the valve disease determining unit 12.

[0053] In this embodiment, for the sake of simplicity, an example has been described in which the valve disease assessment unit 12 assesses valve disease based only on heart sounds. However, the valve disease assessment unit 12 may assess valve disease using pulse waves and electrocardiograms in addition to heart sounds.

[0054] FIG. 8 is a flowchart illustrating the operation of this embodiment.

[0055] In step S10, the R-R interval calculation unit 11b calculates the R-R interval for each heartbeat. In the following step S11, the invalidity determination unit 11e determines whether the R wave of each heartbeat is within ±10% of the average R-R interval, and if there is an R wave exceeding ±10%, the process proceeds to step S15, where the heartbeat is determined to be one for which normal measurement of the second heart sound is impossible (i.e., the heartbeat is excluded from the target).

[0056] On the other hand, for heartbeats that do not have an R wave exceeding ±10%, the process proceeds from step S11 to step S12. In step S12, the corrected QT interval calculation unit 11c calculates the QTc of each heartbeat, and the reference corrected QT interval calculation unit 11d calculates the reference QTc (median QTc).

[0057] In the following step S13, the invalid determination unit 11e determines whether the QTc of each heartbeat is within ±10% of the median. For heartbeats whose QTc is within ±10% of the median, the invalid determination unit 11e shifts from the process of step S13 to the process of step S14, and determines that the heartbeat is one for which the second heart sound can be normally measured. On the other hand, for heartbeats whose QTc is beyond ±10% of the median, the invalid determination unit 11e shifts from the process of step S13 to the process of step S15, and determines that the heartbeat is one for which the second heart sound cannot be normally measured. The determination result of the invalid determination unit 11e is sent to the first and second heart sound detection unit 11f.

[0058] <3> summary As described above, according to this embodiment, there are provided an acquisition unit (cardiogram sound measurement unit 40, electrocardiogram measurement unit 50) that acquires a phonocardiogram and an electrocardiogram of a subject, an electrocardiogram analysis unit 11a that detects the peak time of the R wave, the end time of the T wave, and the start time of the Q wave of the electrocardiogram, a first sound / second sound detection unit 11f that detects the time of the first sound in the phonocardiogram based on the peak time of the R wave detected by the electrocardiogram analysis unit 11a and detects the time of the second sound in the phonocardiogram based on the end time of the T wave, and a first sound / second sound detection unit 11f that detects the time of the second sound in the phonocardiogram based on the end time of the T wave. The reference QT interval calculation unit calculates the QT interval based on the detected T wave end time and Q wave start time, and further calculates a reference QT interval from the QT interval, and the invalidation determination unit 11e detects heartbeats whose QT intervals deviate from the reference QT interval by a predetermined value or more, and invalidates the detection result of the second sound detected based on the T wave end time of the heartbeat. By providing this unit, erroneous detection of the second sound due to erroneous detection of the T wave is suppressed, and as a result, a decrease in the reliability of the diagnosis by the valve disease determination unit 12 is suppressed.

[0059] 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.

[0060] In the above embodiment, the validity or invalidity of the end point of the T wave detected for each heartbeat is determined by determining whether the corrected QT interval for each heartbeat is within ±10% of the median, but the determination criteria are not limited to this. For example, the determination may be made based on whether the corrected QT interval for each heartbeat is within ±5% of the median, or, for example, a heartbeat may be determined to be invalid if the difference in corrected QT intervals between adjacent heartbeats is greater than a predetermined value. In short, a heartbeat whose corrected QT interval deviates from a predetermined standard may be determined to be invalid.

[0061] In the above embodiment, a corrected QT interval (QTc) is calculated and used to determine whether a T wave is invalid, but the present invention is not limited to this. The invalidity of a T wave may be determined using the original, uncorrected QT interval. Essentially, a reference QT interval is calculated from the QT intervals of multiple heartbeats, a heartbeat whose QT interval deviates from the reference QT interval by a predetermined value or more is detected, and the detection result of the second sound detected based on the end time of the T wave of that heartbeat is invalid.

[0062] In the above embodiment, information on the positions of the first and second sounds detected by the heart sound detection unit 11 and information on the invalid second sound are output to the valve disease determination unit 12. However, the present invention is not limited to this, and this information can be output to other diagnostic devices that perform diagnosis based on the first and second sounds.

[0063] In the above-described embodiment, the heart sound detection device and heart sound detection method of the present invention are described as being embodied in a blood pressure pulse wave inspection device 1, but the heart sound detection device and heart sound detection 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.

[0064] In short, the heart sound detection device of the present invention may include an acquisition unit that acquires a phonocardiogram and an electrocardiogram of a subject, an electrocardiogram analysis unit that detects the peak of the R wave, the end of the T wave, and the start of the Q wave in the electrocardiogram, a first sound / second sound detection unit that detects the time of the first sound in the phonocardiogram based on the peak of the R wave detected by the electrocardiogram analysis unit and the time of the second sound in the phonocardiogram based on the end of the T wave, a reference QT interval calculation unit that calculates a QT interval based on the end of the T wave and the start of the Q wave detected by the electrocardiogram analysis unit and further calculates a reference QT interval from the QT interval, and an invalidation determination unit that detects a heartbeat whose QT interval deviates from the reference QT interval by more than a predetermined value and invalidates the detection result of the second sound detected based on the end of the T wave of the heartbeat. Here, the acquisition unit that acquires the phonocardiogram and the electrocardiogram may be the heart sound measurement unit 40 and the electrocardiogram measurement unit 50 as in the above-mentioned embodiment, or may be an input unit such as an interface that inputs information about the heart sounds and the electrocardiogram of the subject. [Industrial Applicability]

[0065] The present invention is widely applicable to a heart sound detection device and a heart sound detection method for detecting the first and second sounds from heart sounds using an electrocardiogram. [Explanation of symbols]

[0066] 1. Blood pressure pulse wave testing device 10. Processing unit 11 Heart sound detector 11a Electrocardiogram analysis unit 11b RR interval calculation section 11c Corrected QT interval calculation section 11d Reference corrected QT interval calculation section 11e Invalidity determination section 11f I and II sound detector 12 Valve Disease Assessment Department

Claims

1. an acquisition unit for acquiring a phonocardiogram and an electrocardiogram of the subject; an electrocardiogram analysis unit that detects the peak time of an R wave, the end time of a T wave, and the start time of a Q wave of the electrocardiogram; a first sound / second sound detection unit that detects the time of first sound in the phonocardiogram based on the peak time of the R wave detected by the electrocardiogram analysis unit, and detects the time of second sound in the phonocardiogram based on the end time of the T wave; a reference QT interval calculation unit that calculates a QT interval based on the T wave end time and the Q wave start time detected by the electrocardiogram analysis unit, and further calculates a reference QT interval from the calculated QT interval; an invalidation determination unit that detects a heartbeat whose QT interval deviates by a predetermined value or more compared to the reference QT interval, and invalidates the detection result of the second sound detected based on the end time of the T wave of the detected heartbeat; A heart sound detection device comprising:

2. The QT interval used in the reference QT interval calculation unit and the invalidity determination unit is a corrected QT interval obtained by correcting the original QT interval by the heart rate.

10. The heart sound detection device of claim 1.

3. the invalidation determination unit calculates a median value of the corrected QT intervals for a plurality of heartbeats as the reference QT interval, detects a heartbeat whose corrected QT interval deviates from the median by a predetermined value or more, and invalidates the detection result of the second sound detected based on the end time of the T wave of the heartbeat. The heart sound detection device of claim 2 .

4. The device further includes a valve disease determination unit that determines a valve disease based on the detection result of the second sound that is not determined to be invalid by the invalidity determination unit.

10. The heart sound detection device of claim 1.

5. An acquisition unit that acquires a phonocardiogram and an electrocardiogram of a subject; an electrocardiogram analysis unit that detects the peak time of an R wave, the end time of a T wave, and the start time of a Q wave of the electrocardiogram; a first sound / second sound detection unit that detects the time of first sound in the phonocardiogram based on the peak time of the R wave detected by the electrocardiogram analysis unit, and detects the time of second sound in the phonocardiogram based on the end time of the T wave; a reference QT interval calculation unit that calculates a QT interval based on the T wave end time and the Q wave start time detected by the electrocardiogram analysis unit, and further calculates a reference QT interval from the calculated QT interval; an invalidation determination unit that detects a heartbeat whose QT interval deviates by a predetermined value or more compared with the reference QT interval, and invalidates the detection result of the second sound detected based on the end time of the T wave of the heartbeat; Equipped with the QT interval used in the reference QT interval calculation unit and the invalidity determination unit is a corrected QT interval obtained by correcting the original QT interval by a heart rate, the invalidation determination unit calculates a median value of the corrected QT intervals for a plurality of heartbeats as the reference QT interval, detects a heartbeat whose corrected QT interval deviates from the median by a predetermined value or more, and invalidates the detection result of the second sound detected based on the end time of the T wave of the heartbeat. Heart sound detection device.

6. obtaining a phonocardiogram and an electrocardiogram of the subject; detecting the peak time of the R wave, the end time of the T wave, and the start time of the Q wave of the electrocardiogram; detecting a time point of the first sound in the phonocardiogram based on the peak time point of the detected R wave and detecting a time point of the second sound in the phonocardiogram based on the end time point of the detected T wave; calculating a QT interval based on the detected T wave end time and Q wave start time, and further calculating a reference QT interval from the calculated QT interval; detecting a heartbeat whose QT interval deviates from the reference QT interval by a predetermined value or more, and invalidating the detection result of the second sound detected based on the end time of the T wave in the heartbeat; A heart sound detection method comprising:

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