Source: https://patents.google.com/patent/US20150088005A1/en
Timestamp: 2018-11-12 23:21:37
Document Index: 2111287

Matched Legal Cases: ['art 110', 'art 110', 'art 110', 'art 110', 'art 110', 'art 110', 'art 110', 'art 110', 'art 110']

US20150088005A1 - Apparatus and method for outputting heart sounds - Google Patents
US20150088005A1
US20150088005A1 US14559069 US201414559069A US2015088005A1 US 20150088005 A1 US20150088005 A1 US 20150088005A1 US 14559069 US14559069 US 14559069 US 201414559069 A US201414559069 A US 201414559069A US 2015088005 A1 US2015088005 A1 US 2015088005A1
US14559069
This application is a continuation of application Ser. No. 14/080,454, filed on November 14, 2013, which is a continuation of application Ser. No. 13/928,674, filed on Jun. 27, 2013, now U.S. Pat. No. 8,663,123, which is a continuation of application Ser. No. 13/456,795, filed on Apr. 26, 2012, now U.S. Pat. No. 8,478,391, which a continuation of application Ser. No. 13/004,543, filed on Jan. 11, 2011, now U.S. Pat. No. 8,167,811, which is a continuation of application Ser. No. 11/037,276, filed on Jan. 18, 2005, now U.S. Pat. No. 7,883,470, which is a continuation of application Ser. No. 09/833,229, filed on Apr. 11, 2001, now U.S. Pat. No. 7,052,466, the specifications of which are incorporated herein by reference in their entirety.
Cardiac pacemakers generally (provide functions including sensing electrical signals generated by the heart, controlling stimulation of excitable tissues in the heart, sensing the response of the heart to such stimulation, and responding to inadequate or inappropriate stimulus or response (e.g., dysrhythmia) to deliver therapeutic stimuli to the heart. Some existing cardiac pacemakers also function to communicate with an external programmer device to support a variety of monitoring, diagnostic and configuration functions.
Certain cardiac pacemakers include an internal accelerometer for measuring the level of activity of the patient (e.g., movement caused by walking around, or by muscle twitches). Such pacemakers process (e.g., filter) the accelerometer signals to reduce noise interfering with the measurement of the patient's activity, such as the sounds generated by the heart itself, and then use the processed signals as inputs to algorithms for generating the signals used to control the stimulation of the heart. For example, if accelerometer signals indicate that a patient is walking briskly, the s pacemaker may stimulate the heart to beat at a faster rate (often subject to an upper rate limit) than when the patient is at rest. While the accelerometer signal is used internally to control the heart rate, this signal is not transmitted by the pacemaker to an external programmer for subsequent display on a display device. Thus, the accelerometer signal itself is an internal signal which is not output to the user.
According to one aspect of the invention, an implantable system includes a sensor for detecting heart sounds and generating sensed signals representative thereof, an interface circuit for communicating with an external system, and a control circuit coupled to the sensor and the interface circuit. The control circuit receives the sensed signals, generates data representative of the heart sounds therefrom, and transmits the data to the external system via the interface circuit. The sensor, interface circuit and control circuit are implantable. In another aspect, an implantable system also includes a second sensor for detecting cardiac electrical signals and generating second sensed to signals representative thereof, and the control circuit also receives the second sensed signals, generates second data representative of the cardiac electrical signals therefrom, and transmits the second data to the external system. In another aspect, an implantable system also includes a third implantable sensor for detecting second cardiac electrical signals and generating third sensed signals representative thereof, and the control circuit receives the third sensed signals, generates third data representative of the second cardiac electrical signals therefrom, and transmits the third data to the external system.
According to another aspect, a method of outputting heart sounds includes receiving data representing heart sounds detected by an implanted system, generating control signals using the data, and applying the control signals to an output device to cause the output device to generate outputs which represent the heart sounds. In another aspect, a method also includes receiving second data representing cardiac electrical signals from the implanted system, and generating the control signals using the second data to cause the outputs generated by the output device to represent the cardiac signals. In another aspect, a method also includes receiving third data representing second cardiac electrical signals from the implanted system, and generating the control signals using the third data to cause the outputs to also represent the second cardiac signals. Other aspects of the present invention will be apparent upon reading the following detailed description of the invention and viewing the drawings that form a part thereof.
FIG. 6 is another exemplary output display screen that is generated by the external device shown in FIG. 1; FIG. 7 is a flow chart showing another embodiment of the processing performed by the controller of the implantable device shown in FIG. 1, including a logbook feature; and
Implantable system 102 includes an implantable device 108 operatively coupled to a patient's heart 110 by a pacing lead 112. The components of implantable device 108 include an atrial sense amplifier 114, a ventricular sense amplifier 116, an atrial stimulating circuit 118, a ventricular stimulating circuit 120, a. controller 122, a memory 124, an accelerometer 126, an analog pre-processing circuit 128, an analog-to-digital (A/D) converter 130, and an input/output (I/O) interface 132. The components of implantable device 108 are housed within an implantable housing (indicated by the broken lined box in FIG. 1.) which is implanted within the patient's chest cavity (e.g., in the pectoral region).
Atrial sense amplifier 114, ventricular sense amplifier 1116, atrial stimulating circuit 118 and ventricular stimulating circuit 120 are operatively coupled to pacing lead 112 via a pair of conductors 134. Pacing lead 112 includes an atrial sensing electrode 136 and an atrial stimulating electrode 138 adapted to be disposed in the right atrial chamber of heart 110, and a ventricular sensing electrode 140 and a ventricular stimulating electrode 142 adapted to be disposed in the right ventricular chamber of heart 110. Sensed atrial and ventricular electrical signals generated by sensing electrodes 136 and 140 are applied to atrial and ventricular sense amplifiers 114 and 116, respectively, and atrial and ventricular stimulating signals generated by atrial and ventricular stimulating circuits 118 and 120 are applied to atrial and ventricular stimulating electrodes 138 and 142, respectively. Atrial sense amplifier 114, ventricular sense amplifier 116, atrial stimulating circuit 118, and ventricular stimulating circuit 120, are each also operatively coupled to controller 122.
In the remainder of this description, implantable device 108 is described as a dual-chamber pacemaker since the present system may be used with patients who have already had a pacemaker implanted in their bodies, thereby alleviating the need to implant a device solely for the purpose of monitoring heart sounds and/or intra-cardial electrical signals, it is to be understood, however, that implantable system 102 need not provide the stimulation functions described herein, and may provide other functions which are not described herein.
Accelerometer 126 is configured to provide sensed signals to analog pre-processing circuit 128, which generates an analog output signal which is digitized by A/D converter 130. The digitized accelerometer signal is received by controller 122. In the embodiment of FIG. 1, accelerometer 126 is located internally to the housing of implantable device 108. In another embodiment, accelerometer 126 is located. externally to the implantable housing. Accelerometer 126 may include, for example, a. piezo-electric crystal accelerometer sensor of the type used by pacemakers to sense the level of activity of the patient, or may include other types of accelerometers that are packaged to fit in the implantable housing. To detect heart sounds, other types of sound-detecting sensors or microphones may also be used, such as pressure sensors or vibration sensors configured to respond to sounds made by the heart.
In one embodiment, accelerometer 126 is configured to generate sensed signals representative of two distinct physical parameters: (1) the level of activity of the patient; and (2) the heart sounds generated by heart 110. Accordingly, analog pre-processing circuit 128 is configured to pre-process the sensed signals from s accelerometer 126 in a manner which conforms to the signal characteristics of both of these physical parameters. For example, if the frequencies of interest for measuring the patient's level of activity are below 10 Hz, while the frequencies of interest for detecting heart sounds are between 0.05 Hz and 50 Hz, then analog pre-processing circuit 128 may include a low-pass filter having a cutoff frequency of 50 Hz. Controller 122 may then perform additional filtering in software using, for example, a low-pass filter with a cutoff frequency of 10 Hz to detect the level of activity of the patient, and a band-pass filter with cutoff frequencies of 0.05 Hz and 50 Hz to detect the heart sounds, although these signal processing functions could also be performed by external system 104. Along with filtering, analog pre-processing circuit 128 may perform other processing functions including automatic gain control (AGC) functions.
In another embodiment, implantable device 108 has two pre-processing channels for receiving sensed signals from accelerometer 126. In still another embodiment, implantable device 108 includes two accelerometers, with one accelerometer configured to generate sensed signals representative of the level of activity of the patient and the other accelerometer configured to generate sensed signals representative of heart sounds, In these latter two embodiments, any hardware and/or software processing performed on the sensed signals can conform to the specific characteristics of the respective sensed signals. For example, the analog pre-processing circuit used for the level-of-activity sensed signals can provide a low-pass filter with a cutoff frequency of 10 Hz, while the analog pre-processing circuit for the heart-sound sensed signals can provide a band-pass filter with cutoff frequencies of 0.05 and 50 Hz. In the latter case, each accelerometer can be selected, located and/or oriented to maximize the detection of the respective physical parameter. In yet another embodiment, if the implantable device does not need to sense the level of activity of the patient, accelerometer 126 may measure only the sounds made by heart 110.
Controller 122 is capable of bi-directional communications with external system 104 via I/O interface 132. In one embodiment I/O interface 132 communicates using RF signals, In other embodiments, I/O interface 132 communicates using optical signals, or a combination of RF and optical signals (e.g., RE signals for receiving data from external system 104 and optical signals for transmitting data to external system 104, or vice-versa). Controller 122 uses I/O interface 132 for bi-directional communications with external system 104 to support conventional monitoring, diagnostic and configuration pacemaker functions.
Controller 122 also uses I/O interface 132 to telemeter data representative of the heart sounds sensed by accelerometer 126 to external system 104. In various embodiments, controller 122 further uses I/O interface 132 to telemeter data representative of cardiac electrical signals (i.e., electrogram or EGM signals), which may include data representative of atrial electrical signals (i.e., A EGM signals) sensed by atrial sensing electrode 136, and/or data representative of ventricular electrical signals (i.e., V EGM signals) sensed by ventricular sensing electrode 140. Thus, implantable system 102 is capable of sensing heart sounds, atrial electrical signals and ventricular electrical signals, and of telemetering data representative of the heart sounds and/or cardiac electrical signals to external system 104. In other embodiments, controller 122 telemeters data representative of cardiac electrical signals which were sensed by other configurations of internal cardiac sensing electrodes.
In one embodiment, external system 104 includes an external device 142 and a surface electrocardiograph (ECG) system 144. External device 142 includes an external controller 146, an I/O interface 148, user input device(s) 150, and user output device(s) 152. Using I/O interface 148, external controller 146 is configured for bi-directional communications with implantable device 108, for receiving input signals from input device(s) 150, and for applying control signals to output device(s) 152. Input device(s) 150 include at least one input device which allows a user (e.g., a physician, nurse, medical technician, etc.) to generate input signals to control the operation of external device 142, such as at least one user-actuatable switch, knob, keyboard, pointing device e.g., mouse), touch-screen, voice-recognition circuit, etc. Output device(s) 152 include at least one display device (e.g., CRT, fiat-panel display, etc.), audio device (e.g., speaker, headphone), or other output device which generates user-perceivable outputs (e.g., visual displays, sounds, etc.) in response to control signals. External controller 146 is configured to receive the data representative of heart sounds, atrial electrical signals and/or ventricular electrical signals from implantable system 102, and to generate control signals that, when applied to output device(s) 152, cause the output device(s) to generate outputs that are representative of the heart sounds, the atrial electrical signals and/or the ventricular electrical signals.
In other embodiments, the processing performed by external controller 146 does not include receiving the atrial and/or ventricular electrical signals (at 302), or receiving surface ECG data (at 304), in which case the corresponding EGM data or surface ECG data is not processed (at 306) or output (at 308). Further, it is contemplated that external controller 146 may not perform any processing of the accelerometer, atrial electrical signals and/or ventricular electrical signals (at 306), and may instead receive corresponding processed data (rather than raw data) from implantable device 108. The processing of these signals (at 306) is illustrated in FIG. 3, however, to indicate that the processing described below in relation to FIG. 4 may well be performed by external device 142 rather than implantable device 108, thereby reducing the computational requirements for implantable device 108. iii Referring to FIG. 4, the signal processing 400 performed on the heart sound data by external controller 146 in accordance with one embodiment of the invention is shown. In other embodiments, some or all of this signal processing could instead be performed by controller 122 of implantable device 108, or by either external or implantable hardware. Signal processing 400 includes a first processing path 402 used for machine detection of heart sounds, and a second processing path 404 used for visual display of heart sounds. Alternatively, only one of heart sound signal processing paths 402 and 404 is provided.
Filtered data 420 is applied to ensemble averager 412 to produce processed accelerometer data 422, which is used for machine detection of heart sounds. Ensemble averager 412 is triggered by an output 424 of a systole detector 426, which is asserted to open a window of interest when the start of a cardiac cycle is detected based upon the electrical systole (which may be detected using the A EGM, V EGM and/or surface ECG signals). Ensemble averager 412 causes the repetitive heart sound data to be averaged over a number of cardiac cycles to accentuate the heart sounds (which are correlated to a particular frequency) while filtering out random or spurious noise (which are not correlated to a particular frequency). For example, ensemble averager 412 may average sequential heart sounds over a period of between 2 and 128 cardiac cycles, although other periods may also be used. In other embodiments, heart sounds are sequentially averaged over a period of time (e.g., one minute), or over the course of an event or condition (e.g., while the patient is performing an exercise), in which case only completed cardiac cycles will be averaged. Note that signal averaging the heart sound data includes the superposition and the summation of successive temporal samples of the pulsatile heart sound waveform. Second processing path 404 includes a band-pass filter 428 and an ensemble averager 430, coupled in series. Raw accelerometer data 414 (representative of the heart sounds) is applied to band-pass filter 428, which has lower and upper cutoff frequencies set to pass frequencies indicative of heart sounds, to produce band-pass filtered data 432. In one example, the lower and upper cutoff frequencies are 0.05 Hz and 50 Hz, respectively. The cutoff frequencies are also set to reject frequencies due to patient movement to the extent that the heart sound signals still pass. Band-pass filtered data 432 is then applied to ensemble averager 430 to produce processed accelerometer data 434, which is used for visual display of heart sounds. Ensemble averager 430 is triggered by output 424 of systole detector 426, which is asserted to open a window of interest when the start of a cardiac cycle is detected based upon the electrical systole. Ensemble averager 430 causes the heart sound data to be averaged over a number of cardiac cycles (e.g., between 2 and 128 cardiac cycles, or other range) to accentuate the heart sounds while filtering out random or spurious noise. By eliminating the rectifier and low-pass filter of processing path 402, processing path 404 avoids eliminating information from the visual display of the heart sound data which may be useful to a physician, nurse, medical technician or other user of system 100.
Output screen display 500 includes multiple horizontal traces, including a surface ECG trace 502 a raw accelerometer trace 504 a processed accelerometer trace 506, an atrial electrical signal (“A EGM”) trace 508, and a ventricular electrical signal (“V EGM”) trace 510. Alternatively, one or more of traces 502-510 may not be displayed. For example, since raw accelerometer trace 504 includes a relatively large amount of noise, this trace may not be displayed since it may not be easily interpreted by a user. Thus, display 500 simultaneously shows a visual trace of all five of these signals, which may be used by a user (e.g., a physician) to diagnose an electrical/mechanical disassociation of heart 110. Note that, if it is desirable for a user at a remote location to aid in the diagnosis of heart 110, the data representative of the heart sounds and electrical signals may be communicated by external device 142 to remote system 154 for display on one of output device(s) 160.
To provide the user with additional operational control, the generation oft heart sound indicia and/or electrical cardiac event indicia on display 500 may be controlled by one or more of input devices 150 (or input devices 158). For example, a first input device (e.g., a switch) may be provided to allow the user to turn the heart sound indicia on or off and a second input device may be provided to turn the electrical event indicia on or off
Referring to FIG. 7, in another embodiment, implantable device 108 includes an arrhythmia logbook feature. With this feature, if an arrhythmia (e.g., an abnormally fast heart rate) detected, implantable device 108 records data in memory for later examination by a physician for use in making a diagnosis. Implantable device 108 may, for example, continually record 10 seconds of data in an area of memory 124, and may simply rewrite over that area of memory. if however, an arrhythmia is detected (e.g., the V EGM signal indicates that heart 110 is beating at an abnormally high rate of 180 beats/minute), the 10 seconds of recorded data is saved in another area of memory 124, along with an additional 20 seconds of data recorded after the arrhythmia. Other arrhythmia events may also be logged. Then, on the next visit of the patient to a doctor, the doctor can use external device 142 to read the data from the logbook, and can examine the data to look for arrhythmia events. For example, the logbook may indicate that, in the three months since the patient was last seen, heart 110 experienced five episodes of fast atrial heart beat, three atrial flutters, and one ventricular fibrillation. The data recorded by implantable device 108 in association with each arrhythmia event may include heart rate data, A EGM data, V EGM data and, in accordance with the present system, raw and/or processed heart sound data.
To provide the arrhythmia logbook feature, in one embodiment, controller 122 of implantable device 108 performs the processing 700 shown in FIG. 7. In particular, controller 122 detects heart sounds by receiving sensed signals representative of the heart sounds from accelerometer 126 (at 702), detects atrial electrical signals by receiving sensed signals representative of the atrial electrical signals from atrial sensing electrode 136 (at 704), detects ventricular electrical signals by receiving sensed signals representative of the ventricular electrical signals from ventricular sensing electrode 140 (at 706), and stores the accelerometer, atrial EGM and ventricular EGM data in memory 124 (at 708). In one embodiment, controller 122 continually stores 10 seconds of such data (along with other desired data, such as heart rate data) in a particular area of memory 124. If controller 122 determines that an arrhythmia has not occurred (at 712) and that no arrhythmia logbook playback request has been received from external device 142 (at 714), controller 122 loops back (to 702), and repeats these operations. As new data is collected and stored in memory 124, the oldest data is re-written by the new data such that the particular area of memory always stores the last 10 seconds of data. If an arrhythmia is detected (at 712), however, controller 122 creates a record in another area of memory (i.e., the arrhythmia logbook), and copies the last 10 seconds of data into that record. Then, for the next 20 seconds, controller 122 continues to monitor data, and stores this data within that same record. Thus, for each detected arrhythmia, controller 122 creates a record in memory 124 that contains data for the 110 seconds leading up to the arrhythmia, and the 20 seconds after the arrhythmia. In other embodiments, less than or more than this amount of data is stored either before or after each arrhythmia occurs. Then, when controller 122 determines that an arrhythmia logbook playback command is received from external device 142, controller 122 transmits the records from memory 124 to external device 142. External device 142 then outputs the data from these records to output device(s) 152 (or output device(s) 160). The physician can then examine the recorded data for each arrhythmia to aid in making a diagnosis. Thus, by using the arrhythmia logbook feature of the system, the physician is provided with heart sound information from both before and after the arrhythmia.
Implantable device 802 includes one or more cardiac sense amplifier(s) 810 and one or more cardiac stimulating circuit(s) 812 operatively coupled to heart electrode(s) 806 via lead 804. In another embodiment, where device 802 does not provide heart stimulation, device 802 does not include cardiac stimulating circuit(s) 812. Device 802 also includes a controller 814, a memory 816 operatively coupled to controller 814, an activity level detecting path 818, a heart sound detecting path 820, a systole detector 822, and an I/O interface 824. Activity level detecting path 818 includes an activity level sensor 826 fir sensing patient activity, an analog pre-processing circuit 828 for pre-processing signals generated by activity level sensor 826, an A/D converter 830 for digitizing the activity level signals, and an activity level filter 832 for filtering the digitized signals to eliminate sources of noise such as those caused by heart sounds. Heart sound detecting path 820 includes a heart sound sensor 834 for sensing heart sounds, an analog pre-processing circuit 836 for pre-processing signals generated by heart sound sensor 834, A/D converter 830 for digitizing the heart sound signals (e.g., using a different channel than the channel used for the activity level signals), a heart sound filter 838 for filtering the digitized signals to eliminate sources of noise such as those caused by patient activity, an S1 heart sound detector 840 for detecting the S1 heart sound, an S2 heart sound detector 842 for detecting the S2 heart sound, and an S3 heart sound detector 844 for detecting the S3 heart sound. Controller 814 transmits data representing the patient's activity level and the S1, S2 and S3 heart sounds to the external device via I/O interface 824. Where S1, S2 and S3 heart sound detectors 840, 842 and 844 ensemble average the heart sound signals, controller 814 provides an output signal indicative of the start of a cardiac cycle from systole detector 822 to heart sound detectors 840, 842 and 844 for use as a trigger. In one embodiment, the outputs from S1, S2 and S3 heart sound detectors 840-844 comprise a sequence of pulses, each pulse representing a detected heart sound. The external device receives the heart sound and cardiac electrical signal data via link 808, and simultaneously outputs this data.
In one embodiment, activity level filter 832, heart sounds filter 838, heart sound detectors 840-844 and systole detector 822 are implemented by controller 814 through appropriate programming commands. In another embodiment, one or more of filters 832 and 838, and detectors 840-844, 822, are implemented by one or more hardware circuits. In another embodiment, sonic or all of the processing functions of
FIG. 8 are performed by the external device instead of device 802. In another embodiment, system 800 includes S1 and S2 detectors 840 and 842, but does not include S3 detector 844. In another embodiment, system 800 includes other sound detectors for detecting other heart sounds. In another embodiment, when an electrical-mechanical disassociation is detected, stimulation timing provided by stimulating electrodes 138 and 142 is changed.
2. A system configured to be coupled to a patient, comprising:
a physiologic sensor circuit configured for sensing a first signal indicative of heart sounds and a second signal indicative of cardiac electrical activity;
a control circuit communicatively coupled to the physiologic sensor circuit, the control circuit configured to:
detect heart sounds using the first signal;
detect cardiac electrical activity using the second signal; and
generate an output control signal using the detected heart sounds; and
an output device configured to generate, in response to the output control signal, a visual presentation based on the first and second signals and a timing comparison between the detected heart sounds and the detected cardiac electrical activity.
3. The system of claim 2, wherein the physiologic sensor circuit is configured to sense the second signal concurrently with the first signal.
4. The system of claim 2, wherein the control circuit is configured to detect the heart sounds when the detected cardiac electrical activity meets a specified criterion.
5. The system of claim 2, where in physiologic sensor circuit is further configured to sense a third signal indicative of physical activity.
6. The system of claim 5, wherein the control circuit is configured to detect the heart sounds when the third signal indicates a physical activity level that meets a specified criterion,
7. The system of claim 2, wherein the output device comprises an audio device configured to generate, in response to the output control signal, audio outputs indicative of heart sounds.
8. The system of claim 2, wherein the physiologic sensor circuit includes one or more physiologic sensors coupled to the patient, and the physiologic sensor circuit senses the first and second signals using the one or more physiologic sensors.
9. The system of claim 8, wherein the one or more physiologic sensors includes an accelerometer configured to sense the first signal indicative of heart sounds.
10. The system of claim 9, wherein the accelerometer is configured to sense the first signal indicative of heart sounds using a first filter, and to sense a third signal indicative of physical activity using a different second filter.
11. The system of claim 8, wherein the one or more physiologic sensors include one or more implantable electrodes configured to sense the second signal including a cardiac electrogram.
12. The system of claim 2, further comprising a transmitter circuit configured to transmit one or both of the first and second signals to a remote system,
sensing, using a physiologic sensor circuit, a first signal indicative of heart :sounds and a second signal indicative of cardiac electrical activity;
transmitting the first and second signals to a control circuit;
processing the first and second signals using the control circuit, including detecting heart sounds using the first signal and detecting cardiac electrical activity using the second signal; and
generating, at an output device, a visual presentation based on the first and second signals and a timing comparison between the detected heart sounds and the detected cardiac electrical activity.
14. The method of claim 13, wherein sensing the first and second signals include sensing the second signal concurrently with the first signal.
15. The method of claim 13, wherein detecting the heart sounds includes ensemble averaging over a portion of the first signal when the second signal indicates intrinsic electric systoles or cardiac stimulation evoked electrical systoles.
16. The method of claim 13, comprising sensing, using the physiologic sensor circuit, a third signal indicative of physical activity, and detecting a physical activity level using the third signal.
17. The method of claim 16, wherein detecting the heart sounds includes ensemble averaging over a portion of the first signal when the detected physical activity level meets a specified criterion.
18. The method of claim 13, comprising sensing an accelerometer signal using an accelerometer, wherein detecting the heart sounds includes detecting the heart sounds using the accelerometer signal.
19. The method of claim 18, comprising sensing a third signal indicative of physical activity, wherein detecting the heart sounds includes filtering the accelerometer signal using a first filter, and detecting a physical activity level includes filtering the accelerometer signal using a second filter.
20. The method of claim 13, wherein sensing the second signal includes sensing a cardiac electrogram using one or more implantable electrodes.
21. The method of claim 13, comprising transmitting one or both of the first and second signals to a remote system.
US14559069 2001-04-11 2014-12-03 Apparatus and method for outputting heart sounds Abandoned US20150088005A1 (en)
US14080454 Continuation US8905942B2 (en) 2001-04-11 2013-11-14 Apparatus and method for outputting heart sounds
US20150088005A1 true true US20150088005A1 (en) 2015-03-26