JPH0442653A - Heart sound transmission system - Google Patents

Abstract

PURPOSE:To allow a medical doctor resident at a remote location to diagnose the operating state of an artificial valve of a patient by sending a frequency component corresponding to a closing sound of the artificial valve and analyzing the frequency of the heat sound signal including the closing sound to be sent. CONSTITUTION:A heat sound signal outputted from a microphone 11 is converted into a digital signal of 64kbps by a band split adaptive differential pulse code modulation (SB-ADPCM) coder 12 and a signal from 50Hz to 70kHz is band-compressed and the result is sent to a digital telephone line 20 in response to a transmission speed of 64kbps via a network controller 13. An SB-ADPCM coder 32 of a hospital 30 receives a reception signal from the digital telephone line 20 via the network controller 31, in which the signal is converted into an analog signal whose frequency is from 50Hz to 7kHz. A spectrum analyzer 33 analyzes the frequency of the analog signal and displays the result of analysis. Thus, a medical doctor resident at a remote location observes the operating state of an artificial valve of a patient in details.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is intended for use in patients whose heart valves have been replaced with artificial valves, in order for doctors to remotely diagnose the operational status of the artificial valves. This paper relates to a heart sound transmission method for transmitting the closing sound of an artificial valve.

[Conventional technology]

Patients with heart valve disease are usually treated by replacing the valve with an artificial valve.

Many metals and carbon are used in the material of this artificial valve, but during long-term use, blood may coagulate due to biochemical reactions with the valve material or other factors. In such cases, the thrombus adheres to the artificial valve, making it difficult for the artificial valve to open and close freely, preventing blood from flowing properly, and causing new diseases.

Therefore, for patients fitted with a prosthetic valve, always pay attention to whether the prosthetic valve is functioning normally, and if blood clots are found attached to the prosthetic valve, surgical or medical treatment should be performed. Thrombectomy procedures are being performed.

By the way, such a diagnosis is made by a doctor listening to the closing sound of an artificial valve. Note that the closing sound is a collision sound between metals and other hard materials that make up the artificial valve, and when the artificial valve is functioning normally, a closing sound with a relatively high frequency is generated. On the other hand, when blood clots begin to adhere to the artificial valve,
Direct contact between hard materials is eliminated, and the frequency and sound pressure of the closure sound are reduced. For example, a typical artificial valve, S.
- In the case of the E valve, frequency components of 6 KH2 or more change due to the attachment of thrombus.

Physicians take advantage of this property and listen to the closing sound of the artificial valve to determine the state of thrombus adhesion to the artificial valve, and if necessary, perform extensive ultrasound echo examinations before removing the corresponding thrombus. Treatment is being carried out.

In the past, it was common for patients to go to the doctor's office to make such diagnoses, but recently doctors can now communicate with patients in remote locations by transmitting heart sounds over telephone lines. It is now possible to diagnose. In other words, patients no longer need to go to the hospital, and their burden has been significantly reduced.

[Problem to be solved by the invention]

However, in diagnosis by listening to the closing sound of an artificial valve, as mentioned above, the key point is the heart sound in a relatively high frequency band (6 kHz or higher for SE valve), and the transmission frequency band is about 3.5 kHz.
When using an ordinary analog telephone line with a frequency of 4 KHz or less, it was not possible to directly hear changes in the closing sound caused by thrombus.

Therefore, conventionally, a rough envelope of the stop sound is extracted and transmitted, and the doctor estimates changes in the stop sound from changes in the shape of this envelope.

However, although this method can detect the presence or absence of a closure sound, it cannot detect changes in the frequency of the closure sound or attenuation of the sound at a specific frequency, making it difficult to diagnose according to the characteristics of the artificial valve, and the diagnostic accuracy inevitably decreases. I didn't get it.

SUMMARY OF THE INVENTION An object of the present invention is to provide a heart sound transmission method that enables the transmission of heart sounds including a frequency band that changes depending on the attachment of blood clots, and that can improve diagnostic accuracy.

[Means to solve the problem]

The invention according to claim 1 includes a heart sound collecting means for collecting heart sounds including the closing sound of an artificial valve and converting the collected heart sounds into a predetermined heart sound signal, and transmitting a heart sound signal in a frequency band corresponding to at least the closing sound of the artificial valve. The apparatus includes a transmission means and a heart sound processing means for frequency-analyzing and displaying the transmitted heart sound signal.

The invention according to claim 2 is the heart sound transmission method according to claim 1, in which the heart sound processing means is configured to set frequency band information of the closure sound specific to each artificial valve, and to adjust the frequency band information corresponding to the closure sound accordingly. This configuration includes a function to display the frequency analysis results of heart sounds separately from the frequency analysis results of other heart sounds.

The invention according to claim 3 is the heart sound transmission method according to claim 1, in which the heart sound collecting means specifies the frequency band of the closure sound that corresponds to the type and shape of each artificial valve and changes due to the attachment of thrombus. The heart sound processing means includes a function of generating a reference signal of a predetermined frequency and a predetermined level and sending it to the transmission means, and the heart sound processing means displays the frequency analysis result of the reference signal to identify the frequency band of the closing sound corresponding to each artificial valve. This is the configuration used.

[For production]

According to the first aspect of the invention, since it is possible to transmit a heart sound signal in a frequency band corresponding to the closing sound of an artificial valve, the frequency change and level of the closing sound can be displayed on the receiving side. That is, a doctor in a remote location can diagnose the operating state of the artificial valve based on the frequency analysis result of the heart sound signal displayed on the heart sound processing means.

The invention according to claim 2 distinguishes the frequency analysis result of the band corresponding to the closure sound from the frequency analysis result of the transmitted heart sound according to the frequency band information of the closure sound corresponding to the artificial valve used by the patient. By displaying the information, doctors can easily diagnose multiple types and shapes of artificial valves.

The invention according to claim 3 transmits, together with the heart sound signal, a reference signal of a predetermined frequency and a predetermined level that corresponds to the type and shape of each artificial valve and specifies the frequency band of the closing sound that changes due to the attachment of thrombus. , the receiving side can display the frequency analysis results of the reference signal that can be clearly distinguished from others.

In other words, a doctor in a remote location can determine the frequency analysis result of the band corresponding to the closure sound by referring to the display position of the frequency analysis result of the reference signal, without knowing the type and shape of the patient's artificial valve in advance. and its operating status can be easily diagnosed.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of the invention as set forth in claim 1.

In the figure, a microphone 11 fixed to the patient's chest, the output of the microphone 11 is taken into the patient's house 10,
Band division/adaptive differential pulse code modulation (SB-ADPCM) that performs analog/digital conversion and predetermined encoding
Encoding device 12 and SB-ADPCM encoding device 1
A network control unit (NCU) 18 is installed to control the connection between the telephone line 2 and the digital telephone line 20.

The hospital 30 facing the patient's home 10 via the digital telephone line 20 includes a network control unit (NCU) 31 connected to the digital telephone line 20, an SB-ADPCM decoding device 32, and an SB-ADPCM decoding device 32. A spectrum analyzer 33 that takes in the output of the heart sound, performs frequency analysis of the transmitted heart sound signal, and displays the frequency analysis results.
will be installed.

Note that the microphone 11 corresponds to the heart sound collecting means, and the SB
- ADPCM encoding device 12, network control device 13, digital telephone line 20, network control device 31 and SB-ADP
The CM decoding device 32 corresponds to a transmission means, and the spectrum analyzer 33 corresponds to a signal processing means.

In addition, the SB-ADPCM encoding method used in this embodiment converts a 7 KHz band audio signal into a 50 Hz to 4 KHz audio signal.
.

A known technology (CCIT
Recommendation G, 722).

In such a configuration, the heart sound signal output from the microphone 11 is processed by the SB-ADPCM encoder 12.
Converts to 4Kbps digital signal and further 50H
The signal from Z to 7 KHz is band-compressed and sent via the network controller E13 to the digital telephone line 20, which supports a transmission rate of 64 Kbps. Therefore, from the patient's home 10 to the hospital 30, heart sounds containing frequency components that are lowered or attenuated due to the attachment of the thrombus to the artificial valve can be transmitted.

At the hospital 30, the received signal from the digital telephone line 20 is input to the SB-ADPCM decoding device 32 via the network control device 31, and is converted into an analog signal from 50 Hz to 7 KHz. The spectrum analyzer 33 analyzes the frequency of this analog signal and displays it.

FIG. 2 is a diagram showing a display example of the spectrum analyzer in the embodiment of the invention set forth in claim 1. Here, the horizontal axis is frequency and the vertical axis is power spectrum.

For reference, FIGS. 3(a) and 3(c) show frequency analysis results of heart sound signals transmitted using a conventional analog telephone line when the artificial valve is normal or abnormal, respectively. As shown in the figure, analog telephone lines do not transmit high-frequency components corresponding to the closing sound, which is essential for determining the operating state of the artificial valve, so frequency analysis results can be used to determine whether the artificial valve is normal or abnormal. I can't.

On the other hand, FIGS. 2(a) and 2(b) show the results of frequency analysis of heart sound signals transmitted using the digital telephone line 20 shown in this embodiment, respectively, when the artificial valve is normal or abnormal.

When using the digital telephone line 20, broadband transmission targeting heart sounds from 50 Hz to 7 KHz is possible, so as shown in FIG. 2(a), there is a noticeable peak on the high frequency side. If the peak corresponds to the closing sound specific to the artificial valve, it can be determined that the artificial valve is normal. In other words, it can be diagnosed that no thrombus is observed attached to the artificial valve.

In addition, as shown in Figure 2 [Yes], if the peak level on the high-frequency side has decreased or if a spectrum corresponding to the inherent closing sound of the artificial valve cannot be obtained, the artificial valve may be affected by the adhesion of blood clots. It can be diagnosed that the door is not opening or closing properly.

In this way, the doctor can make a diagnosis based on the frequency analysis results displayed on the spectrum analyzer 33 and take appropriate treatment.

However, when heart sound signals arrive from many patients via digital telephone lines, and when there are many types of artificial valves to be diagnosed, it is necessary to analyze the closing sounds of the artificial valve used by the patient in advance. Knowing the frequency characteristics is necessary for accurate diagnosis.

Therefore, the invention according to claim 2 is characterized by having a function of displaying a signal in a frequency band corresponding to the closing sound of an artificial valve used by a patient, distinguishing it from others. Here, when a thrombus adheres to the artificial valve used by a patient, the closing sound at the lower limit frequency where the sound pressure changes greatly is defined as the characteristic closing sound (6 KHz in the case of S and -E valves).

For example, in the case of the above-mentioned embodiment, the frequency of the characteristic stop sound is preset as data in the spectrum analyzer 33, and the frequency corresponding to the characteristic stop sound is set as a boundary line, color coded, or other method. The high-frequency side and the low-frequency side are distinguished and displayed.

By adopting such a configuration, it becomes easy for the doctor to target only the spectral waveform related to the closing sound of the patient's artificial valve, and the operating state of the artificial valve can be reliably diagnosed from the frequency analysis results. can.

FIG. 4 is a block diagram showing the configuration of an embodiment of the invention according to claim 3.

In the figure, a microphone 1 installed at a patient's home 10'
1. SB-ADPCM encoding device 12 and network control unit (NCU) 13; furthermore, network control unit (NCU) 31 installed in the hospital 30 facing the patient's home 10 via the digital telephone line 20, and SB-ADPCM decoding The converter 32 and the spectrum analyzer 33 are similar to those in the embodiment of the invention shown in FIG.

The feature of this embodiment is that a reference sound oscillator 17 that generates a signal (reference sound) of the same frequency as the characteristic closing sound of the artificial valve used by the patient is provided in the patient's home 10', and This reference sound is added to the heart sound of the patient and is synthesized and transmitted as a single sound. In addition, when the SE valve mentioned above is used as an artificial valve, the frequency of the reference sound is 6KH2.

Further, the output level of the signal power of the reference sound outputted from the reference sound oscillator 17 is set so as to be sufficiently larger than the output power of the microphone 12.

With this configuration, the spectrum analyzer 33 in the hospital 30 simultaneously displays a frequency peak corresponding to the reference sound emitted from the reference sound oscillator 17 at the patient's home 10' and a plurality of peaks corresponding to heart sounds. In addition, the reference tone (
Since the frequency peak corresponding to the characteristic stop sound is significantly larger than other peaks, the spectral waveform corresponding to the stop sound can be easily identified based on the frequency peak.

FIG. 5 is a display example of the spectrum analyzer in the embodiment of the invention set forth in claim 3, and (a) and (■) are frequency analyzes of the reference sound and heart sound when the artificial valve is normal or abnormal, respectively. This is the result. here,
The horizontal axis is frequency, and the vertical axis is power spectrum.

As shown in the figure, the frequency peak corresponding to the reference sound,
Multiple peaks corresponding to heart sounds are displayed simultaneously, so
The spectral waveform corresponding to the closing sound of the artificial valve can be easily identified.

In other words, as shown in Figure 5(a), if there is a prominent peak in the high range of the reference sound and that peak corresponds to the unique closing sound of the artificial valve, then the artificial valve is normal. It can be determined that there is no thrombus attached.

In addition, as shown in Figure 5 (b), if the peak level of the high frequency side of the reference sound has decreased or if a spectrum corresponding to the inherent closing sound of the artificial valve cannot be obtained, it may be due to the attachment of a blood clot. It can be diagnosed that the artificial valve is not opening and closing normally.

In this way, when transmitting heart sounds from a patient's home, by simultaneously transmitting a reference sound that corresponds to the characteristic closing sound of the artificial valve being used, it is possible to eliminate the possibility that multiple patients are using different artificial valves. Doctors can also make an appropriate diagnosis without knowing in advance the frequency characteristics of the closing sound of the artificial valve used by the patient.

In addition, without simultaneously transmitting heart sounds and reference sounds from the patient's home,
The reference sound may be transmitted for a predetermined period of time, and then only the heart sound may be transmitted. In this case, the doctor recognizes the frequency of the reference sound using the spectrum analyzer 33, and then reads the frequency analysis result of the heart sound. becomes. That is, although the position of the characteristic closing sound cannot be simultaneously displayed in the frequency analysis result of the heart sound, the operating state of the artificial valve can be diagnosed based on the doctor's memory.

Further, although the above-described embodiment is an example corresponding to the S-E valve, it is similarly applicable to other artificial valves.

In addition, the transmission speed of the digital telephone line that transmits the heart sound signal is not particularly limited as long as it can transmit high frequency components higher than the characteristic closing sound that is essential for determining the operating state of the artificial valve. It is also possible to use a broadband analog telephone line such as a dedicated line.

Furthermore, in the embodiments shown in FIGS. 1 and 4, the patient's home 10.10' and the hospital 30 are connected online, and the patient's heart sound information is transmitted to the doctor in real time. The heart sound information may be stored once on a magnetic tape, magnetic disk, or the like and then transmitted, and the heart sound information received at the hospital 30 may also be stored once and then analyzed.

〔Effect of the invention〕

As described above, the invention according to claim 1 enables the transmission of the frequency component corresponding to the closing sound of an artificial valve, and by frequency-analyzing the transmitted heart sound signal including the closing sound, the invention can be transmitted to a remote location. Doctors in the hospital will be able to diagnose the operating status of the patient's artificial valve.

The inventions recited in claims 2 and 3 further enable a display that corresponds to the frequency characteristics of the artificial valve used by the patient, making it easier for a doctor to diagnose a plurality of types and shapes of artificial valves.

In other words, a doctor in a remote location can determine the frequency band corresponding to the closure sound by referring to preset data or the display position of the frequency analysis result of the reference signal, without knowing the type and shape of the patient's prosthetic valve in advance. The frequency analysis results can be identified and the operating status can be easily diagnosed.

In this way, the doctor can observe the operating status of the patient's prosthetic valve in detail while being in a remote location. Therefore, malfunction of the artificial valve can be diagnosed earlier than conventionally, and it becomes possible to prevent the patient's condition from worsening.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the invention according to claim 1. FIG. 2 is a diagram showing a display example of the spectrum analyzer in the embodiment of the invention as set forth in claim 1. FIG. 3 is a diagram showing a display example of a spectrum analyzer when a conventional analog telephone line is used. FIG. 4 is a block diagram showing the configuration of an embodiment of the invention according to claim 3. FIG. 5 is a diagram showing a display example of the spectrum analyzer in the embodiment of the invention according to claim 3. 1O110'...Patient's home, 11...Microphone,
12...SB-ADPCM encoding device, 13.31.
...Network control unit (NCU), 17...Reference tone oscillator, 20...Digital telephone line, 30...Hospital, 3
2... SB-ADPCM decoding device, 33... Spectrum analyzer. (a) ('b) Fig. (a) αri Fig. (a) α→ Fig.

Claims (3)

[Claims] (1) A heart sound collection means that collects heart sounds including the closing sounds of the artificial valve and converts them into predetermined heart sound signals; A transmission means that transmits heart sound signals in a frequency band corresponding to at least the closing sounds of the artificial valve; and transmission means. 1. A heart sound transmission method comprising: heart sound processing means for frequency-analyzing and displaying a heart sound signal generated by the heart sound. (2) In the heart sound transmission method according to claim 1, the heart sound processing means is set with frequency band information of the closure sound specific to each artificial valve, and the heart sound processing means transmits the frequency analysis results of the band corresponding to the closure sound to other valves. A heart sound transmission method characterized by including a function of displaying heart sound frequency analysis results separately. (3) In the heart sound transmission method according to claim 1, the heart sound collecting means has a predetermined frequency and a predetermined level that correspond to the type and shape of each artificial valve and specify the frequency band of the closure sound that changes due to the attachment of thrombus. The heart sound processing means includes a function of generating a reference signal and sending it to the transmission means, and the heart sound processing means is configured to display a frequency analysis result of the reference signal and use it to identify the frequency band of the closing sound corresponding to each of the artificial valves. A heart sound transmission method characterized by: