Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B7/00—Instruments for auscultation
  • A61B7/02—Stethoscopes
  • A61B7/04—Electric stethoscopes

Definitions

• the present invention relates to an auscultation heart sound signal processing method and an auscultation apparatus.
• a simple stethoscope listens to detected heart sounds with earphones to determine whether the heart sounds are normal or abnormal.
• a probe is Sound is detected, and the detected heart sound signal is recorded as heart sound data.
• the detected heart sounds or further recorded heart sounds are listened to by the earphones, and the recorded heart sound data is analyzed and used to determine whether the heart sounds are normal or abnormal.
• the recorded heart sound signal is also transmitted over a line and used in such a form that a specialist at a remote location inspects the heart sound.
• a computer-assisted method is used in which heart sound analysis is performed on heart sound data to assist in diagnosis of heart disease.
• a dedicated system for professionals is large-scale and difficult to use for general users.
• the simpler and smaller ones for general users have made it difficult to accurately identify abnormal heart sounds.
• a stethoscope or auscultation device is disclosed in the following patent documents.
• Patent Document 1 Japanese Patent Laid-Open No. 2005-52521
• Patent Document 2 Japanese Patent Publication No. 10-504748
• Patent Document 3 JP-A 61-290936
• Patent Document 4 JP-A-5-309075
• Patent Document 1 converts sound acquired by a microphone into an electrical signal, and selectively enhances a signal in a frequency range corresponding to a heart sound and a signal in a frequency range corresponding to a breathing sound.
• electronic stethoscopes that set the frequency characteristics of the equalizer to selectively attenuate signals in other frequency ranges.
• Patent Document 2 includes an electronic auscultation that includes a digital filter for pre-emphasis, hearing loss compensation, and the like, and has a pattern recognition means for suppressing repetitive signals in the observed signal and removing noise. It is written on the vessel.
• the heart sound meter disclosed in Patent Document 3 is a heart sound meter for a general user such as a household user, and can use a heart sound waveform signal with a simple configuration using a general-purpose personal computer.
• the heart sound detected by the heart sound probe includes noise, and when listening to the heart sound transmitted depending on how much gain adjustment is performed in the heart sound conversion device, or transmitting and receiving heart sound data.
• Patent Document 4 in order to accurately determine heart sound data without setting a determination criterion, the amplitude of the heart sound is stored together with the elapsed time, and the characteristics of a predetermined portion of the stored amplitude are depicted. Based on the above, there is disclosed a heart sound analysis apparatus that performs predetermined recognition by a Yural network, outputs the degree of recognition, and displays the degree of abnormality of heart sounds.
• This heart sound analyzer uses a force neural network that sets the borderline in determining the necessity of precision screening required in the primary screening of heart screening. It is not easy to use o
• the heart sound analysis method in the preceding invention is based on the heart sound data force measured using the tympanic membrane vibration model to obtain the vibration response and analyze and evaluate the time widths of the peak I sound and stuttering sound. This is to detect abnormalities.
• abnormalities of heart sounds can be confirmed by analyzing and evaluating the time span obtained by vibration response force, but the shape of heart sound data and vibration response is the type and characteristics of heart sound abnormalities. This analysis method may not be able to accurately grasp abnormal heart sounds for various characteristics of abnormal heart sounds.
• the heart sound signal that can have various characteristics is efficiently removed, noise is effectively improved, the sound quality is improved, and the heart sound recording level is improved. It is inadequate to listen to and discriminate heart sounds recorded with proper sound quality, and to transmit heart sound signals to remote locations for use, making the device complicated and expensive. There was a difficulty of becoming a thing.
• the sound quality of the heart sound auscultation sound is improved, the sound is low and the heart sound auscultation sound is easy to hear, the recording level of the heart sound signal is set appropriately, and the normal / abnormal heart sound is also detected. It was desired to analyze the heart sound signal so that it could be accurately and quantitatively determined. It was also desired to adjust the detected heart sound signal to an appropriate volume for listening to the heart sound, processing and analyzing the heart sound signal.
• the present invention has been made to solve the above-mentioned problems, and the auscultatory heart sound signal processing method for performing heart sound analysis for detecting abnormal heart sounds according to the present invention sets model parameters of a vibration model. Detecting heart sounds, thereby obtaining heart sound data, generating feature value waveform data for the obtained heart sound data under set model parameters, and threshold (THV) For the evaluation value indicating the time width and time interval of the peak of the feature value waveform data, and the evaluation index power is also defined by using the fuzzy member function (w), the center of the data set (V) And the evaluation function J (W, V) representing the distribution of the evaluation index from the center of the evaluation index and data set, and the center of the data set so that the evaluation function is minimized by iterative calculation. To decide And the predetermined Minimum evaluation function value Ci for range THV)
• Each step force is to select the THV that minimizes m, and to display the evaluation index obtained for the selected THV and the distribution state of the center of the data set.
• the auscultation device includes means for setting model parameters of a vibration model, heart sound detecting means for detecting heart sounds and thereby obtaining heart sound data, and setting for the obtained heart sound data.
• Means for obtaining the center (V) of the data set to be determined means for obtaining an evaluation function 3 ⁇ 4J (W, V) representing the distribution of the evaluation index from the center of the evaluation index and the data set, and the evaluation function A means for determining the center of a data set by iterative calculation so as to minimize, a means for obtaining a minimum evaluation function town where the evaluation function is minimum, and a dependence of J on a predetermined range of THV are obtained, and within that range
• the auscultatory heart sound signal processing method for performing heart sound signal processing for sound quality improvement in auscultation includes setting a model parameter of a vibration model to form a vibration model and detecting a heart sound.
• To obtain the heartbeat signal to obtain the feature value waveform data output by applying the obtained heart sound signal to the vibration model, and to obtain the heart sound signal or the signal obtained by removing high-frequency component noise as heart sound data.
• the phase lag is calculated by taking the cross-correlation between the heart sound data and the feature value waveform data, and the phase lag is divided so that there is substantially no phase difference between the heart sound data and the feature value waveform data.
• the output heart sound data is obtained as a product of shifting the phase of the feature value waveform data only by the product of the heart sound data and the feature value waveform data shifted in phase by the phase delay. , But also made steps force.
• the heart sound signal may be normalized before the heart sound signal is applied to the vibration model.
• the auscultation apparatus inputs a heart sound signal detected by the heart sound detecting means or a signal obtained by removing noise of a high frequency component from the heart sound data as a heart sound data, thereby inputting characteristic value waveform data corresponding to the heart sound data.
• a vibration model to be output a phase lag calculation unit that calculates a phase lag of the feature value waveform data with respect to the heart sound data by cross-correlating the feature value waveform data output by the vibration model and the heart sound data;
• a multiplication conversion unit that takes a product of the feature value waveform data and the heart sound data, the phase of which is shifted by the phase delay so that there is substantially no phase difference between the heart sound data and the feature value waveform data; It also has a heart sound signal processing unit that performs heart sound signal processing to detect abnormal heart sounds.
• the auscultation apparatus includes a probe for converting a heart sound into an electric signal, and the probe.
• An automatic volume adjustment recording unit that records and outputs a heart sound by adjusting and amplifying the signal of the heart sound obtained by the audio signal, and the time of the signal of the heart sound obtained by the probe by the automatic volume adjustment recording unit ⁇ Suitable for amplifying heart sound signals based on average intensity between
• a microcomputer control unit that obtains an up gain so as to obtain a proper volume and controls amplification of a heart sound signal, and a time T following the time T according to the obtained up gain under the control of the microcomputer control unit. Amplifies the heart sound signal and records the amplified signal ab
• It is also possible to provide a means for automatically adjusting the sound recording volume comprising an amplification adjusting unit that can be extracted as a power sound.
• the microcomputer control unit holds a relationship of the magnitude of the up gain for amplifying the sound intensity to an appropriate sound volume with respect to the calculated average intensity of the heart sound signal, and refers to the table. Try to amplify the heart sound signal to an appropriate volume.
• the time T force ⁇ is a time within a range of 3 seconds, and the time T force is within a range of 12 seconds.
• the time T may be in the range of 8 to: LO seconds.
• the heart sound recording sound volume automatic adjusting means may be configured as a transmission side unit so that the amplified heart sound signal can be transmitted to the reception side unit.
• the heart sound feature value waveform and the heart sound signal obtained using the heart sound data and the vibration model are substantially eliminated from the phase difference, and the impulse is obtained as output heart sound data. Therefore, the heart sound of the peak part is emphasized and the noise part is weakened with respect to the original heart sound data, and the sound quality is easy to hear when played back, and it is efficient by inexpensive methods and devices.
• the sound quality of the heart sound auscultation sound can be improved accurately, and it can contribute to the accurate determination of normal / abnormal heart sounds.
• the evaluation index and the center of the data set are defined for the feature value waveform generated from the heart sound data using the vibration model so that the evaluation function expressed thereby is minimized.
• the center of the data set is determined in order to obtain the evaluation index and the processing result for the center of the data set, which is easy for general users to use and takes various forms. Quantify the normality / abnormality of heart sounds with respect to the characteristics of abnormal heart sounds Can be distinguished
• the up-gain is calculated using a reference table based on the average intensity between
• the recorded heart sound signal is used in the form of analyzing the heart sound signal so that normality / abnormality of the heart sound can be discriminated, and further, the recorded heart sound signal is listened to, or When a heart sound signal transmitted to a remote location is listened to, it is considered to handle the heart sound signal in a heart disease diagnosis system such as that used in a rectangular shape.
• the recorded heart sound signal is processed! Based on the eardrum vibration model, the heart sound signal is processed using the characteristic value waveform.
• the features of the present invention are as follows: (A) feature value waveform based on vibration model, (B) heart sound signal analysis processing for abnormal heart sound detection, (C) heart sound signal processing for sound quality improvement in auscultation, (D The explanation is divided into the aspects of) automatic adjustment of the volume of heart sound recording, and (E) auscultation device configuration.
• the heart is divided into four parts: the left atrium, the left ventricle, the right atrium, and the right ventricle. As a whole, it plays the role of a pump that circulates blood throughout the body by repeating contraction and relaxation.
• These valve membranes prevent blood backflow. Is the sound emitted when these valve membranes close.
• FIG. 1 is a conceptual diagram showing an eardrum vibration model.
• 1, 1 is an object having an equivalent mass of m corresponding to the eardrum
• 2 is an object having one end corresponding to the eardrum 1 and the other end being fixed to the fixed part
• 3 is one end. Is a damper in which the other end is attached to the fixed part to the object corresponding to the object 1 corresponding to the eardrum.
• the equivalent mass of object 1 corresponding to the eardrum is m
• the spring constant of spring 2 is K
• the viscous damping coefficient of damper 3 is C
• the vibration response X of the eardrum is calculated from the equation (1).
• Equation (1) Equation (1)
• It may be an electric vibration system having a scale and electric capacity.
• Fig. 2 (a) shows the results of the normal heart sound force vibration response X based on the tympanic membrane vibration model described in (A), and Fig. 2 (b) shows the mitral valve closure based on the tympanic membrane vibration model.
• Incomplete heart sound force Shows the results of vibration response.
• the heart sound data is recorded in a commercially available heart sound auscultation training material.
• the parameter p in Eq. (3) is 10 Hz, and is 0.707.
• the gray waveform is the original waveform of heart sound S.
• the solid line waveform shows the vibration response, and the waveform showing this vibration response is called the feature value waveform.
• Fig. 2 (a) represents a normal heart sound that can be heard as "dock, dock”
• Fig. 2 (b) represents a heart sound in which the mitral regurgitation sounded as "go, goo”.
• the waveforms in Fig. 2 (a) and (b) are characteristic value waveforms with positive and negative amplitudes, but it is only necessary to analyze either the positive or negative waveform part.
• Fig. 3 (a) shows a feature value waveform portion having a positive amplitude when the feature value waveform is analyzed.
• I sound and stuttering appear repeatedly in a normal heart sound waveform. This I sound is caused by the closure of the mitral and tricuspid valves, and the II sound is caused by the closure and tension of the aortic and pulmonary valves.
• the I sound and II It is considered effective to analyze and evaluate the sound duration (peak duration).
• Fig. 3 (a) the vertical axis indicates the intensity of the heart sound, the horizontal axis indicates the time, and the measurement time is shown for 2 seconds.
• Two I sound peaks 48 and two stuttering peaks 49 each. It has been extracted.
• the duration (time width) of the I sound peak 48 and the stuttering peak 49 is obtained from the point where this threshold line intersects the feature value waveform, and each The evaluation index is Tl and ⁇ 2.
• the starting force of the I sound peak 48 followed by the end of the II sound peak 49 is also set to the duration until the start of the next I sound peak 48.
• the evaluation index is T11.
• Tl, T2, T12, Til are used in appropriate combination.
• FIG. 3 (b) plots the points indicated by (Tl, T2) and (Ti l, T12) with Tl and Tl l on the horizontal axis and ⁇ 2 and ⁇ 12 on the vertical axis. Normal or abnormal heart sounds are determined. In other words, with normal heart sounds, the points represented by the evaluation index tend to gather in the categories surrounded by dotted lines as shown in Fig. 3 (b).
• the heart sound is normal when a point represented by the evaluation index enters the region of the normal value range, and the heart sound is abnormal when the point does not fall within this region.
• the range of normal values is the default for many healthy individuals. It is desirable to obtain data and determine statistically.
• the horizontal axis is the type of evaluation index
• the vertical axis is the frequency of each evaluation index during the measurement time of 10 seconds. You can compare the frequency of the index. For example, if T2 is clearly less than evaluation index T1, there is a possibility of an arrhythmia that is not observed due to the loss of II sound peak 49, and this evaluation index is used when T11 is represented by multiple bars. It is visually determined that there is a variation in the value of.
• FIG. 2 (a) The waveforms shown in (b) have various shapes depending on the type of heart sound abnormality, and depending on the type and degree of abnormality, it may be difficult to accurately determine heart sound abnormality.
• the threshold (THV) for defining the evaluation indices Tl, T2, Tl l, and T12 is set to 50%.
• This THV was a force not considered otherwise.
• the threshold setting is an important factor for heart sound analysis. It was surprising that it was greatly affected by the recording conditions and individual differences among the measurement subjects.
• the threshold is a force that can be set in the range of 0 to: LOO%. From the actual situation, the range of 10 to 70% is reasonable.
• Figure 4 (a) shows the relationship between the heart sound feature value waveform and T HV when THV is 15%, 30%, and 60%, respectively.
• Figure 4 (b) and (c) 5 is a distribution diagram of points indicated by evaluation indices (T 1, T2) and (Ti l, Tl 2) obtained for THV of the present invention.
• the distribution of the evaluation index differs as shown in Fig. 4 (b) and (c) depending on the THV setting for the characteristic value waveform shown in Fig. 4 (a).
• the fuzzy C means (FCM) data clustering method is used as the data grouping method.
• FCM has been proposed in various ways, and is one of the data clustering methods.
• the cluster center position ⁇ v ⁇ is determined so that the evaluation function is minimized by iterative calculation. Specifically, first, the initial value of the member function matrix ⁇ w ⁇ is set by fuzzy theory, and the cluster center position ⁇ v ⁇ ,
• W is recalculated as follows using the Euclidean distance d obtained in the previous calculation.
• Normal heart sounds differ to some extent, and the effective threshold range of THV also varies slightly. Generally, in the case of normal heart sounds, the value of J becomes minimum, or the THV that reaches the valley state as shown in Fig. 7 There is a range, and in that range J can be said to be a very small value of about 0.01.
• FIG. 7 shows the heart rate data for atrial fibrillation and atrial flutter (AF, arrhythmia), mitral stenosis (MS), and aortic regurgitation (AR).
• the effective threshold range is 16% to 46%, and for MS in Fig. 7 (b), the effective threshold range is 45% to 66%.
• the effective threshold range is 10% to 22%.
• J is lower than 0.02 in the effective threshold, and the distribution of the points represented by the center of the data set and the evaluation index is within a certain range.
• the values at least one or more values are extremely high compared to normal heart sounds.
• the center of the data set is about the same as in the case of normal heart sounds, and the minimum evaluation function city within the range of the force effective threshold is 0.4 compared to the case of normal heart sounds.
• the value of J within the effective threshold range is small, but the value indicating the center of the data set is much larger than that of normal heart sounds.
• J is not necessarily minimized at one point of THV, but may be substantially minimized within a certain range (when it becomes valley-shaped within a certain range of THV). In such a case, select the THV range and select the range internal force THV as appropriate.
• the signal processing using the feature value waveform is performed based on the vibration model described in (A). It is advantageous to use a digital circuit for the vibration model type conversion circuit, and the auscultation heart sound is preferably converted into a digital heart sound signal by first performing AZD conversion before being input to the conversion circuit. Further, if the efficiency of signal processing is important, it is preferable to perform normality representing the signal value as a ratio to the maximum value.
• FIG. 10 shows the result of obtaining the vibration response X by giving a heart sound signal to the vibration model, which is the same as FIG.
• the vertical axis indicates the signal intensity.
• the heart sound signal Y (i) has positive and negative values
• S (i) Zm is changed to S below.
• the gray waveform is the original waveform of the input heart sound data S (i).
• the solid line waveform shows the vibration response x (i). This waveform data is the characteristic value waveform data.
• the heart sound data waveform S (i) and feature value waveform data x (i) in FIG. The portion that corresponds to the heart sound, and the portion with a low value between the peaks contains noise.
• the heart sound data Y (i) force is also extracted by wavelet analysis to extract high-frequency components of 5 kHz or more or 2.5 kHz or more. ) Is preferably used as heart sound data.
• the heart sound data S (i) and the feature value waveform data x (i) are obtained by multiplying the peaks by matching the peaks, thereby reducing the noise in the heart sound data and reducing the heart sound itself. By emphasizing, it is considered that the heart sound data is finally reduced in noise.
• phase delay k For this purpose, it is necessary to obtain the phase delay k and shift the phase of the waveform of x (i) by this phase delay, that is, take the product with the phase of S (i). Phase lag
• phase difference k is obtained as the value of i when (i) is maximized.
• p (i) is a sequence of cross-correlation functions, and S and X represent average values.
• This k is a sequence p (i)
• phase difference can be substantially eliminated by using k.
• x (k + i) [x (k + l) x (k + 2) ---- x (N)]
• the output heart sound data of TS (i) obtained in this way was reproduced by enhancing the heart sound of the peak portion and weakening the noise portion of the original heart sound data.
• the sound quality is easy to hear, and it is also accurate for analyzing heart sounds.
• the heart sound signal processing method for enhancing the heart sound and weakening the noise according to the present invention is shown as a flow chart in FIG.
• the heart sound is converted into a heart sound signal with a microphone that converts it into an electrical signal, and the heart sound signal is listened to with a earphone to determine whether the heart sound is normal or abnormal, and as described in (B) and (C).
• a heartbeat signal there is a form of performing a heartbeat analysis or processing for improving the sound quality of the heartbeat.
• the heartbeat signal is first recorded at the stage of recording. It is important to adjust the volume to an appropriate level
• method (i) is suitable for heart sound feature numerical analysis, it cannot be amplified because the volume is set to an appropriate level by lowering the volume. In the method (ii), the volume can be increased or decreased. However, if the input signal is too small, it becomes difficult to determine the data force volume level after AZD conversion.
• the amplification degree of the heart sound signal is controlled from the data after the AZD conversion, and sound analysis is considered with respect to the obtained heart sound data. This method is used. In other words, the amplification level at the probe is maximized and sent to the volume control section. Set it to come out.
• the basic idea of adjusting the recording volume of heart sounds according to the present invention is that the first relatively short !, data for gain adjustment is acquired during time T, and the subsequent time T is acquired.
• the ab heart sound signal should be properly amplified and used.
• appropriate gain adjustment is made by setting how much the heart sound signal is amplified in a short time before amplifying the heart sound to be used. Time to acquire data for gain adjustment T
• a is about 1 to 3 seconds, and about 2 seconds is most appropriate. This is because the normal heartbeat period is 0.8 to 1 second, and if heart sounds of about 2 periods can be collected, it can be used as data for gain adjustment. Time to amplify heart sound to use T is about 4-12 seconds
• the recording volume of the heart sound is adjusted according to the following procedure.
• This volume adjustment is performed according to the following procedure according to the operation of the microcomputer on the AD signal of the detected heart sound signal.
• the time T (1 to 3 seconds) for acquiring data and the heart sound to be used are amplified for gain adjustment as described above
• the up gain necessary to amplify the heart sound to be used is set as a gain reference table.
• Threshold value x is defined for heart sound volume x (i), and x (i)> x during time T
• steps (1) to (4) are carried out at least once, but it is usually recommended to repeat several times (2 to 5) times.
• the automatic adjustment of the heartbeat recording volume in steps (1) to (4) is performed by the microcomputer 23.
• the microcomputer 23 holds a program necessary for such control, a gain reference table, and the like.
• FIG. 13 is a diagram showing a state of a heart sound signal when a heart sound is recorded by the procedures (1) to (4).
• Fig. 13 shows the original heart waveform signal
• (b) shows the heart waveform signal during time T for calculating the gain
• (c) shows the up-state obtained by the signal in (b).
• a waveform signal is shown. Hearts captured during time ⁇ before recording heart sounds like this a
• the up-gain is determined, and the heart sound signal is amplified to an appropriate volume accordingly, so that the heart sound recorded in the stage (c) of FIG. 13 has an appropriate volume.
• Figure 14 shows the NZS ratio when the heartbeat recording volume is automatically adjusted according to steps (1) to (4) and when the heartbeat is recorded without such automatic adjustment of the heartbeat recording volume.
• the horizontal axis indicates how many heart sounds are recorded.
• FIG. 15 schematically shows the form of the auscultation device according to the present invention.
• the auscultation device detects the heart sound, and the volume of the heart sound signal detected by the probe a is appropriately increased.
• the sound volume processing and recording section b which adjusts the sound volume
• the sound volume processing section c which performs sound volume enhancement and noise reduction processing for the heart sound signals recorded and adjusted by the automatic volume adjustment recording section b
• Automatic sound volume adjustment recording unit b Adjusts the sound volume by the heart sound signal recorded by S, and performs heart sound analysis to determine whether the heart sound is normal or abnormal. It has a heart sound analysis processing unit d and a receiving unit e that generate data to be provided separately.
• the heart sound signal recorded by adjusting the volume at the automatic volume adjustment recording unit b, or the heart sound signal subjected to the heart sound enhancement and noise reduction processing by the heart sound signal processing unit c can be heard by the monitoring means. In addition, it is transmitted to a remote location by the transmission means.
• the result of the analysis of the heart sound signal recorded by the automatic sound volume control unit b with the volume adjusted is displayed on the monitor or the result of the analysis process is displayed. It is transmitted by the transmission means.
• the receiver e can receive the transmitted heart sound signal and analyzed data and use it to determine whether the heart sound is normal or abnormal, or to process the received signal and data.
• FIG. 15 shows an example of the configuration, and in addition to the probe a, it is possible to combine it as necessary.
• the element parts in the apparatus configuration of FIG. 15 will be described separately.
• FIG. 16 shows elements of the auscultation probe a, the automatic volume control recording unit b, and the receiving unit e in the auscultation apparatus of FIG.
• the recorded heart sound signal is transmitted with the volume adjusted, and is received by the receiving unit e.
• the heart sound signal processing unit c in FIG. A form or a form in which the transmitted heart sound is received by the receiving unit e and the heart sound signal processing unit c performs enhancement of the heart sound and noise reduction processing can be considered.
• an auscultation probe a includes a chest piece 11 that includes a microphone that detects a heart sound and converts it into an electrical signal, an amplification unit 12 that amplifies the detected heart sound signal, and an amplified heart sound.
• the amplifying unit 12 includes a preamplifier, a filter, and a power amplifier, and is amplified to an appropriate level and a heart sound signal is sent to the volume automatic adjustment transmission module 10.
• the automatic volume adjustment recording unit b includes a signal adjustment unit 21, an AZD conversion unit 22, a microcomputer 23, a high-pass filter 24, an amplification adjustment unit 25, and a transmitter 26.
• the signal adjustment unit 21 includes a high-nos filter and a signal adjustment circuit.
• the signal adjustment unit 21 adjusts the heart sound signal received from the amplification unit 12 of the auscultation probe a and sends it to the AZD conversion unit 22 and the no-pass filter. 24 to amplifying unit 25 via 24.
• Amplification adjustment unit 25 is also a high-pass signal conditioner of signal adjustment unit 21 It includes a control amplifier, signal conditioner, and high-pass filter that amplifies the heart sound signal sent through the filter 24 to an appropriate gain in response to a command from the microcomputer.
• the heart sound signal sent to the AZD conversion unit 22 is converted into 8-bit (10-bit or 12-bit) digital data and processed by the microcomputer 23.
• the amplification of the heart sound signal is controlled.
• the time Ta (1 to 3 seconds) for acquiring data for gain adjustment and the time Tb (4 to 12 seconds) for amplifying the heart sound to be used are set in advance. Keep a reference table that gives the up-gain. Based on the average intensity of the heart sound signal obtained with the auscultation probe a during time T
• the reference table power is calculated so that the up gain is obtained and the microcomputer control unit performs amplification control of the heart sound signal, and the time T following the time T according to the obtained up gain under the control of the microcomputer control unit. Amplifying the heart sound signal between
• the heart sound signal is taken out and listened to by the earphone, and the amplification adjustment unit 25 amplifies and adjusts it so that it can be transmitted by the transmitter 26.
• the receiving unit e has a receiver 31, an adjusting unit 32, and an amplifying unit 33 for receiving a heart sound signal transmitted from the transmitter 26 of the automatic volume adjustment recording unit b.
• the signal is monitored by earphones or used for heart sound analysis by a computer. Further, it can be amplified as an analog output by an amplifier.
• Automatic volume adjustment and recording unit b side force receiving unit The transmission to the e side may be performed by wireless transmission via an antenna or via a cable.
• FIG. 17 (a) and 17 (b) show the configuration of the heart sound signal processing unit c.
• Fig. 17 (a) shows the whole heart sound signal processing unit, and the heart sound signal processing unit c includes the AZD conversion unit of the automatic volume adjustment recording unit b obtained after the heart sound detection unit of the auscultation probe a.
• the signal Y (i) converted into a digital signal at is input.
• the signal adjustment unit 43 that takes the absolute value of the AZD-converted heart sound signal Y (i) and performs processing such as normal ⁇ , and the signal S (i) from the signal adjustment unit 43 is input and the feature value waveform X (i ) Forming the vibration model 44 and the signal from the signal adjustment unit 43.
• Filter part 45 that outputs noise data S (i) and heart sound from filter part 45
• the data and the characteristic value waveform data from the vibration model 44 are input and the signal processing is performed, and the heartbeat is emphasized and the noise is weakened. Yes.
• the signal adjustment unit S (i) the force signal S (i) is input to the vibration model 44.
• the vibration model 14 is converted to the heart sound data S (i) from which high-frequency component noise has been removed in the force filter unit 45. In that case, the same heart sound data
• the data SW (i) is also input to the conversion circuit unit 46.
• 47 is a parameter setting unit for setting parameters in the vibration model 44.
• FIG. 17 (b) shows the conversion circuit unit 46 in FIG. 17 (a) in more detail.
• the conversion circuit unit 46 includes a phase lag calculation unit 51 and an integration conversion unit 22. It is configured.
• the heart sound data S (i) and the feature value waveform data x (i) are multiplied by the phase delay calculation unit 51, respectively.
• the value of the phase delay k input to both of the conversion units 52 and obtained by the phase delay calculation unit 51 is input to the multiplication conversion unit 52.
• the multiplication conversion unit 52 shifts x (i) by the phase delay k to x (k + i), calculates the product with S (i), and outputs the result.
• the heart sound signal processing unit shown in FIGS. 17 (a) and 17 (b) includes a part for processing the digitized signal in the A / D conversion unit 12 and a memory for recording the heart sound signal. It can be configured as a digital circuit and built into the auscultation device, or it can be formed as a unique device that processes the signals using the recorded heart sound signals.
• FIG. 18 shows the configuration of the heart sound analysis processing unit d.
• a is a heart sound detection unit
• b is an automatic volume adjustment recording unit that performs AZD conversion of the heart sound signal detected by the heart sound detection unit a and adjusts the volume
• the heart sound data that has been AZD converted and volume adjusted is the heart sound processing analysis processing unit d Is input.
• the heart sound analysis processing unit d includes a parameter setting unit 61 that sets model parameters of the vibration model, a feature value waveform generating unit 62 that generates feature value waveform data of heart sound data under the set model parameters, and a threshold value (THV).
• TSV threshold value
• Means for obtaining the evaluation index 63 Means for obtaining the center of the data set defined by using the member function from the evaluation index 64, Means for obtaining the evaluation function from the evaluation index and the center of the data set 65, Evaluation by iterative calculation Means to determine the center of the data set so that the function is minimized 66, for a given range of THV Means 67 for determining the THV that minimizes the minimum evaluation function value Ci), and means 68 for sending display data such as an evaluation index for the selected THV and the center of the data set to the display unit 70. .
• the parts 62 to 67 perform arithmetic processing on the input data according to the set parameters, and these arithmetic processes may be performed to form a dedicated circuit including a memory or as shown in FIG. It may be configured to be executed by a personal computer equipped with a program for performing arithmetic processing according to the above flow.
• the display unit 70 displays data obtained as a result of heart sound analysis, and a display having a screen such as a liquid crystal panel may be used.
• the display contents are displayed as a graph without numerical values of the evaluation index and the distribution status at the center of the data set.
• the result obtained by the arithmetic processing in the heart sound analysis processing unit d may be transmitted to the receiving unit at a remote location by the transmission means in addition to being displayed on the display unit 70 as display data.
• the heart sound analysis processing unit d requires a means for accumulating and holding necessary items such as definition formulas necessary for the analysis of heart sound data, and further, actual data actually obtained by heart sound analysis is stored in a database. By providing a means for storing and storing the data, the data can be used as comparison data when performing a new heart sound analysis.
• the present invention can be used to perform automatic adjustment of heart sound recording volume, improvement of sound quality of heart sound signals, and analysis processing of heart sound signals, respectively, and as an auscultation device in a combination of them. It can also be used.
• FIG. 1 is a conceptual diagram showing an eardrum vibration model.
• FIG. 2 (a) shows the results of obtaining the vibration response X of the normal heart sound force based on the tympanic membrane vibration model, and (b) shows the mitral regurgitation heart sound vibration based on the tympanic membrane vibration model. It is a figure which shows the result which calculated
• FIG. 3 (a) is a diagram showing how to obtain the evaluation index in the case of normal heart sounds, (b) is a diagram showing the correlation of the evaluation index, and (c) is a diagram showing the frequency of the evaluation index. It is.
• FIG. 5 (a) and (b) are diagrams showing examples of defining the center of data collection by the PCM clustering method for the correlation of evaluation indices, and (c) is the minimum evaluation obtained by the PCM clustering method. It is a figure which shows the dependence with respect to the threshold value of a function value.
• FIG. 6 (a) and (b) are graphs showing the correlation of evaluation indices with threshold values ranging from 10% to 70%.
• C) and (d) are threshold values ranging from 30% to 60%. It is a figure which shows the correlation of the table
• FIG. 8 (a), (b) for arrhythmia (AF), (c), (d) for mitral stenosis (MS), (e), (f) for aortic regurgitation It is a figure which shows the correlation of an evaluation index, respectively in the case of (AR).
• FIG. 9 is a diagram showing a flow of heart sound analysis according to the present invention.
• FIG. 11 is a diagram showing the characteristic value waveform in FIG. 10 shifted by the phase delay.
• FIG. 12 is a diagram showing a flow of processing of a heart sound signal.
• FIG. 13 is a diagram showing a state of a heart sound signal when a heart sound is recorded.
• FIG. 14 is a diagram showing a comparison of NZS ratios when the heartbeat recording volume is automatically adjusted according to the present invention and when heartbeats are recorded without automatic adjustment.
• FIG. 15 is a diagram showing a schematic configuration of an auscultation apparatus according to the present invention.
• FIG. 16 is a diagram showing an automatic volume adjustment recording unit and a consultation unit in the configuration of FIG.
• FIG. 17 (a) is a diagram showing a heart sound signal processing unit in the configuration of FIG. (b) It is a figure which shows especially about the conversion circuit part among (a).
• FIG. 18 is a diagram showing a heart sound analysis processing unit in the configuration of FIG. Explanation of symbols

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• 2006
  • 2006-10-20 JP JP2007541064A patent/JP4848524B2/ja active Active
  • 2006-10-20 WO PCT/JP2006/320964 patent/WO2007046504A1/ja active Application Filing
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