WO2009068297A1

WO2009068297A1 - Mobile ekg recorder for cardiologic monitoring of patients

Info

Publication number: WO2009068297A1
Application number: PCT/EP2008/010112
Authority: WO
Inventors: Wilfried Scharner; Tilo Borchardt; Rene Tauscher; Robert Hartmann
Original assignee: Vitaphone Gmbh
Priority date: 2007-12-01
Filing date: 2008-11-28
Publication date: 2009-06-04
Also published as: DE102008003321A1

Abstract

The invention relates to a mobile EKG recorder (1) for cardiologic monitoring of patients, designed to detect, store, and transmit single or multi-channel EKG segments, having a plurality of EKG sensing electrodes (2) for sensing at least one EKG signal (20), having an EKG storage (10) for the storage of EKG signals (20), and having means for the transmission of the EKG signal (20) to a receiver station. The EKG recorder (1) can be supported on the body of the patient, and the EKG sensing electrodes (2) can be applied for a long period of time to the body of the patient. According to the invention, an evaluation function is provided which is designed to evaluate the EKG signal (20) and automatically detect heart rhythm disturbances, wherein the evaluation and the detection is carried out before transmission to the receiver station.

Description

Mobile ECG recorder for cardiac monitoring of patients

The invention relates to a mobile ECG recorder for cardiac monitoring of patients, designed for the acquisition, storage and transmission of single- or multi-channel ECG sections, with a plurality of ECG removal electrodes for the acceptance of at least one ECG signal, with an ECG Memory for storing the ECG signal and means for transmitting the ECG signal to a receiving station, wherein the ECG recorder on the body of the patient is portable and wherein the ECG pickup electrodes are permanently applied to the body of the patient.

From telecardiology mobile ECG recorders are known, which are used for the monitoring of mobile or immobile endangered patients. The known recorder are usually designed or have a corresponding functionalization that recorded an ECG with the mobile recorder, transmitted by phone to an evaluation center and evaluated there. The recording of ECG signals or ECG sections is carried out manually in the event of symptoms, i. the patient decides whether to take an ECG scan. After recording, the ECG is transmitted, which is associated with a complex handling. In addition, it is disadvantageous that when mild or unrecognized symptoms of heart rhythm disorder occur, the patient does not cause ECG recording, so that not every heart activity disorder can be detected.

Object of the present invention is to provide a mobile ECG recorder of the type mentioned above, which allows the measurement, storage and transmission of ECG signals or ECG sections in a simple manner and ensures high monitoring security of the patient, said occurring disorders of the heart activity of the patient should be reliably detected in each case.

CONFIRMÄΠON COPY To achieve the above object is provided in a mobile ECG recorder of the type mentioned that an evaluation function is designed to evaluate the ECG signal and for the automatic detection of cardiac arrhythmias, wherein the evaluation and detection is carried out before transmission to the receiving station ,

The invention is based on the basic idea to automatically detect selected cardiac arrhythmias, i. without active participation of the patient. The selected cardiac arrhythmias may be, in particular, bradycardia, tachycardia, atrial fibrillation, pauses and asystole. In the invention, an evaluation function is provided to automatically determine the cardiac rhythm of the patient from the measured ECG signal or from a recorded ECG section to automatically define, i. to detect pre-determined selected cardiac arrhythmias. This simplifies the handling of the ECG recorder and, moreover, ensures a high degree of monitoring security for the patient, whereby the automatic detection of cardiac arrhythmias eliminates the need for active involvement of the patient in the detection. Since not every cardiac arrhythmia is accompanied by symptoms, so also arrhythmias are detected, which would otherwise go undetected.

The term "ECG signal" is understood to mean the measured cardiac action potential of the patient, the measurement leading to an ECG section over a predetermined period of time. The term "ECG section" describes the part of a heart potential curve acquired over a certain period of time, which results from the measured ECG signal. The ECG recorder according to the invention can be designed to accommodate single or multi-channel ECG sections and have a corresponding number of ECG removal electrodes. The detached ECG signal may be partially sectioned as an ECG section, i. as part of a heart potential curve, stored, analyzed and transmitted.

Preferably, the measured ECG signal is automatically evaluated or analyzed, without requiring an operator action of the patient to activate the evaluation function. It is understood that the evaluation function can also be activated manually by the patient, in particular at felt disorders of heart activity or malaise. Also, an automatic evaluation can be done periodically after expiration of predetermined periods.

In a further preferred embodiment of the invention, it is provided that the ECG signal can be continuously evaluated in real time. As a result, cardiac arrhythmias can be detected promptly to their occurrence. This contributes to a high surveillance security of the patient. For the detection of cardiac arrhythmias, it is preferably provided that the heart potential curve available from the measured ECG signal is analyzed, whereby changes in the course of the removed cardiac potential curve are detected continuously and in real time.

The evaluation function can be designed for the automatic detection of heartbeats, wherein, preferably, R-waves in the cardiac potential curve are automatically determined, in particular threshold-based according to the MOBD method ("multiplication of backward differences"). The detection of heartbeats is based on the recognition of the steep flanks of R-waves in the cardiac potential curve. Since the amplitude of the signal alone is not a sufficient recognition criterion for this, not the signal itself, but its (mathematical) derivative of the first degree is considered for the detection. Because this emphasizes steep increases compared to non-steep sections of the signal curve. In the MOBD method, the current signal amplitude (Sn), the signal amplitude after the expiration of a first time duration (Sm) and the signal amplitude after the expiration of a second longer time duration (S1) are considered. The derivative then corresponds to:

(Sn - Sm) ^• (Sm - Sl).

The MOBD method is characterized by a high noise immunity. The noise susceptibility results from the fact that smaller signal fluctuations, which brings the noise, are smoothed by the calculation of the difference. In order to generate a large derivative to be searched for, the signal must increase over the entire length of 30 ms. This is not the case with disturbances due to noise. In a further preferred embodiment of the invention, the evaluation function is designed for automatic threshold checking in the threshold value-based determination of R waves by the MOBD method. In order to detect heartbeats safely, at least one threshold is provided, which adapts to the size of the derivative of a detected heartbeat. If the signal is smaller, then the threshold is lower, the signal is greater, so the threshold will settle to a larger value. Since the size of the signal amplitude is not present at the beginning of the evaluation of the ECG signal, the threshold value is initialized very large and then oscillates according to a defined visual wave value reduction from above to the magnitude of the derivative of the detected heartbeat. In particular, a defined threshold reduction can take place, provided that for a short time no heartbeats are detected.

Moreover, the evaluation function for automatic monitoring of the signal quality of the ECG signal may be formed, wherein, preferably, before the threshold value adjustment, a check of the signal quality and, and more preferably, with low signal quality, an interruption of the detection of cardiac arrhythmias or the continuous evaluation of the ECG signal is provided. As a result, cardiac arrhythmias are detected only on the basis of ECG signals with high signal quality, which contributes to the reliable detection of cardiac arrhythmias.

In order to be able to reliably detect disturbances in cardiac activity, the evaluation function can be designed for the automatic determination of R-R distances in the current cardiac potential curve, wherein, preferably, the current heart rate can be determined from the last measured R-R intervals.

Moreover, it may be provided for the detection of cardiac arrhythmia that the evaluation function is designed for the automatic evaluation of heartbeats, wherein, preferably, a QRS complex corresponding pattern for a first detected heartbeat is formed, the similarity of the QRS complex of a subsequent heartbeat is determined automatically with the pattern, and where a detected similarity, a new pattern from the subsequent heartbeat is formed. In the case of With a predetermined degree of similarity between the QRS complex of a subsequent heartbeat with the first detected heartbeat, a new pattern is then formed from the subsequent heartbeat. The evaluation of the heart beats or their classification serves to detect abnormal beats as these influence the decision-making in atrial fibrillation. According to the invention, a pattern is initially formed from the first detected beat, wherein the patterning is preceded by a high-pass filter in order to eliminate signal interference. Then, with each further detected beat, a comparison is made with the pattern, whereby the similarity of the current beat to the beat represented by the pattern is determined. If there is a low similarity, then the current stroke is classified as abnormal, otherwise as a normal beat, in general, a normal QRS complex. If there is a normal strike, a new pattern is created from the last beat. The pattern comparison thus takes place adaptively.

Moreover, it may be provided in connection with the automatic detection of cardiac arrhythmias that the evaluation function for the automatic detection of cardiac arrhythmias is formed by comparing the determined R-R distances with R-R pattern distances. The R-R pattern spacings are stored in the recorder and allow the detection of defined selected cardiac arrhythmias.

The detection of cardiac arrhythmias presupposes that the cardiac output curve is determined in order to be able to determine from the progress of the cardiac activity disturbances. The ECG recorder according to the invention can have at least one memory function designed for preferably automatic (long-term) storage of the ECG signal upon detection of a cardiac arrhythmia.

The ECG recorder according to the invention can also be designed as an event recorder with loop function. An ECG signal is continuously recorded over several minutes. When the loop memory is filled, recording starts again from the beginning. The oldest ECG data will be overwritten. Due to the continuous recording of the ECG signal, pathological deviations are documented and can be detected by a correspondingly formed software can be detected automatically. It can be provided that immediately after the expiry of a predefined time interval after the occurrence of an automatically detected ECG deviation, the software forwards the ECG to a mobile telephone and / or a call center. ECG sections that have pre-defined defined cardiac arrhythmia can also be stored permanently, with overwriting with newly recorded ECG data not provided. By permanently storing only those ECG sections where pathological deviations occur, the storage requirements for long-term storage can be reduced. Moreover, it is ensured that not any anomaly is stored. It is understood that a permanent storage can also be triggered manually.

Incidentally, the memory function can allow the automatic timed feeding of ECG signals. Here, a periodic storage of the ECG signals over a fixed period of time may be provided. Also, a long-term monitoring of the patient is possible, with the measured cardiac potential changes are stored continuously.

In addition, a memory blocking function can be provided in such a way that no memory of the ECG signal is possible after activation of the memory blocking function. For example, after activation, even if a new cardiac arrhythmia is detected, no event storage can be triggered, which is necessary during the post-time and when the algorithm for analyzing the ECG signal is not completed. Moreover, there are advantages in frequently occurring arrhythmias.

In order to further simplify the handling of the ECG recorder according to the invention, the transfer function can be designed such that when an arrhythmia occurs, the ECG signal is automatically transferable to the receiving station, preferably wirelessly via radio and / or infrared and / or wired, wherein the ECG signal before transmission into an audio signal is convertible, preferably according to the FSK method ("frequency shift keying"). Preferably, a transmission via audio as well as via radio / infrared is equally possible. The ECG according to the invention Recorder thus has for the first time a device for converting the ECG signal into an audio signal and a device that allows the transmission of the ECG signal via radio / infrared. There are thus two device functions realized in a device or a unit, which is not known from the prior art. This contributes to a high compatibility of the ECG recorder according to the invention in connection with ECG transmission.

In this context, the invention allows, as needed, that the ECG signal is transmitted to the receiving station in real time after the detection of a cardiac arrhythmia, which allows a very rapid detection of a cardiac arrhythmia in the receiving station and contributes to the monitoring security of the patient. Preferably, however, it is provided that the ECG is transmitted only after the storage, that is not in real time. For example, it is possible that previously stored ECG sections or parts of a recorded heart potential curve are transmitted upon detection of a specific cardiac arrhythmia. It is essential that no operator action of the patient is required for the transmission. The central station can then forward the ECG signal or the relevant ECG section to a physician for evaluation, or an evaluation of the ECG in the central station can be provided. Moreover, a data encryption can be provided in connection with the transmission, wherein the evaluation device can have an anonymization function for the anonymization of the ECG data. This ensures high data security.

The receiving station can be a service center or a computer to which the ECG is transmitted. Moreover, the transmission of the ECG signal or the ECG section to the receiving station via a mobile phone is possible. If the ECG is transmitted by radio, an immediate transmission to a PC can be provided in order to be able to display and evaluate the ECG there. In addition to the radio transmission, preferably via Bluetooth, and the infrared transmission, the transmission can be made by wire. The recorder according to the invention preferably has both means for radio transmission and infrared transmission and / or for line-bound transmission. Here it can be provided that the Recorder has means for ECG transmission via telephone, modem, mobile phone or smart phone alike.

When converted into an audio signal in the FSK method, the transmission function can be designed such that, with high transmission quality, fast transmission and, in the case of poor transmission quality, for example via a mobile radio network, automatically slow transmission of the ECG signal or the ECG signal. Section is provided. As a result, even with disturbed networks transmission is reliably possible. Moreover, the transfer function can be designed for the automatic detection of transmission errors. This contributes to the high surveillance security of the patient.

In the ECG recorder according to the invention, a call number of the receiving station can be stored for automatic transmission. This simplifies automatic transmission, which is beneficial for both transmission after detected arrhythmia and manual ECG storage.

In a further preferred embodiment, the evaluation function can be designed for automatic detection of ischemia characters in multi-channel ECG sections. In addition to the assessment or detection of cardiac arrhythmias, it is contemplated at this point of the invention to also detect ischemic signs in multichannel ECG sections, which supports the indication of a myocardial infarction and a heart attack monitoring of the patient.

In particular, there are a variety of ways to design and further develop the ECG recorder according to the invention, reference being made on the one hand to the dependent claims and on the other hand to the following description of a preferred embodiment of the invention with reference to the drawings. In the drawing show

Fig. 1 shows schematically the structure of an ECG recorder according to the invention for cardiac monitoring of patients and 2 is a schematic diagram of the method sequence for the acquisition, evaluation and storage of an ECG signal with the ECG recorder shown in FIG. 1.

On the basis of FIG. 1, the structure of an ECG recorder 1 for cardiac monitoring of patients is to be described schematically, wherein the ECG recorder 1 is designed for the acquisition, storage and transmission of single or multi-channel ECG sections. The ECG recorder 1 has a plurality of ECG pickup electrodes 2 for picking up at least one ECG signal 20. After amplification of the ECG signal 20 with an ECG amplifier 3, an analog-to-digital conversion with an A / D converter 4 and digital filtering with a digital filter 5, the ECG signal 20 is fed to an evaluation device 6. The evaluation device is designed, inter alia, for the automatic evaluation of ECG signals 20 and for the automatic detection of defined cardiac arrhythmias, wherein the evaluation and detection takes place prior to the transmission of the ECG signal 20 or the ECG section to a receiving station, not shown. Incidentally, the ECG recorder 1 can be worn on the patient's body, whereby the ECG removal electrodes 2 can be permanently applied to the body of the patient.

Depending on the setup set 8 or depending on the programming of the evaluation device 6, the automatic detection of the heart rhythm and the detection of cardiac arrhythmias occur. This will be discussed below. Following the rhythm detection and detection of arrhythmia, the ECG signal 20 is compressed by means of a compression function 9. For storing the ECG signal 20 or ECG sections, a memory 10 of a memory device is provided, wherein the storage can be triggered manually via a memory button 11. In addition, the automatic storage of ECG signals 20 or ECG sections in detection of a defined arrhythmia is possible, which will be discussed below.

The transmission of the stored ECG signal 20 or of the ECG section to the receiving station can be effected manually by means of a transmit button 12 or also automatically by the recorder when a cardiac arrhythmia is detected. according to the setup setting and the set transmission mode. The ECG recorder 1 has a transmission device 7 with means 13 for the wireless transmission of the stored ECG signal 20 or of stored ECG sections as an infrared signal 14 or radio signal 15. In addition, the transmission device 7 has means 16 for the wired transmission of the stored ECG signal 20. In this context, it can be provided that the ECG signal 20 can be converted into an audio signal 17 before transmission according to the F SK method. The transmission can be done via a not shown mobile phone in a central office or directly to a PC.

Finally, control elements 18 or a keyboard are provided via which the recording of the ECG signal 20 or an ECG section can be triggered manually. Incidentally, the operating elements 18 make it possible to set the transmission mode and to carry out setup settings and other auxiliary settings, for example during pairing. A display 19 allows the display of status and error displays and the display of the heart rate or even the measured ECG signal 20.

With reference to FIG. 2, the automatic rhythm recognition will be explained in more detail below with the ECG recorder 1 described in FIG. The automatic rhythm recognition is based on the detection and evaluation of defined cardiac arrhythmias. The ECG signal 20 is fed in real time to an evaluation module 21 which detects selected heartbeats in the MOBD method. The MOBD method is particularly susceptible to noise, ie, despite certain artifacts, a detection is possible. In a subsequent threshold module 22, the threshold value is checked, which is the basis of the heartbeat detection in the MOBD method, so that reliable beat detection is ensured at different ECG amplitudes. In the event that for a short time no shocks can be detected, a defined threshold value reduction takes place in a further, second threshold module 23. If a defined threshold reduction is required, there is no storage of the ECG signal 20, which is shown schematically by the node 24 in FIG. If R-waves are detected after the reduction in threshold value, storage takes place when the cardiac arrhythmia is detected. If a new heartbeat has been detected, the signal quality of the ECG signal 20 in a quality assurance module 25 is automatically monitored. With low signal quality, in turn, no storage of the ECG signal 20 is provided, which leads to the node 24. Noise, potential overdriving or very low amplitudes result in the temporary interruption of the further signal evaluation.

If the ECG signal 20 has a good quality, the ECG signal 20 is supplied to a further, third threshold module 26, wherein the threshold value is adaptively adapted to the signal amplitude after a detected heartbeat.

The following further, second evaluation module 27 is designed to automatically determine the R-R distances in the measured ECG signal 20 or in a recorded cardiac potential curve, wherein first the current heart rate is determined from the last R-R intervals. The actual rating of the heart beats, i. the recognition of cardiac arrhythmias is achieved by an adaptive pattern comparison in a subsequent further, third evaluation module 28 and by an evaluation of the R-R distances in a further, fourth evaluation module 29. The evaluation of heartbeats depends on the limits set in setup 8. In the case of a detected heart rhythm disorder, it is first checked whether the storage is blocked. For this purpose, a storage blocking module 30 is provided, wherein in the case of blocked storage, even if the cardiac arrhythmia is detected, no event storage can be triggered, which in turn leads to the reaching of the node 24. If there is no cardiac arrhythmia, storage of ECG signals 20 is also not provided. If the memory blocking is deactivated, automatic event storage of the ECG signal 20 occurs, which results from reaching the end point 32 according to FIG. 2.

To determine and provide free memory resources, a memory module 31 is provided. The memory module 31 decides on several memory modes: Save until the storage capacity of the memory 10 is reached,

Saving only selected cardiac arrhythmias, i. selective storage, and

Deleting stored ECG signals 20 or ECG sections according to a hierarchy system.

A module is understood to mean a specific functionalization or programming of the ECG recorder 1 described, wherein all the described modules can be combined in one microcontroller and at least one ECG signal 20 is supplied to the microcontroller for processing in the loop mode. The ECG signal 20 is continuously analyzed by the microcontroller for defined arrhythmia.

Claims

claims:

1. A mobile ECG recorder (1) for the cardiac monitoring of patients, designed for the acquisition, storage and transmission of single or multi-channel ECG sections, with a plurality of ECG removal electrodes (2) for accepting at least one ECG signal ( 20), an ECG memory (10) for storing the ECG signal (20) and means for transmitting the ECG signal (20) to a receiving station, wherein the ECG recorder (1) on the body of the patient is portable and wherein the ECG removal electrodes (2) can be permanently applied to the body of the patient, characterized in that an evaluation function is provided for evaluating the ECG signal (20) and for automatic detection of cardiac arrhythmias, wherein the evaluation and the detection before transmission to the receiving station.

2. ECG recorder according to claim 1, characterized in that the removed ECG signal (20) is automatically evaluated.

3. ECG recorder according to claim 1 or 2, characterized in that the ECG signal (20) is continuously evaluated in real time.

4. ECG recorder according to one of the preceding claims, characterized in that the evaluation function is designed for the automatic detection of heartbeats, wherein, preferably, R-waves are automatically detected, in particular threshold value based on the MOBD method.

5. ECG recorder according to claim 4, characterized in that the evaluation function is designed for automatic threshold checking in the threshold-based determination of R-waves according to the MOBD method.

6. ECG recorder according to claim 4 or 5, characterized in that the evaluation function is designed for automatic threshold value adjustment.

7. ECG recorder according to one of claims 4 to 6, characterized in that the evaluation function is designed for the defined threshold reduction, if for a short time no heartbeats are detected.

8. ECG recorder according to one of the preceding claims, characterized in that the evaluation function for automatically monitoring the signal quality of the ECG signal (20) is formed, wherein prior to the threshold value adjustment, a check of the signal quality of the ECG signal (20) takes place and , Preferably, with low signal quality an interruption of the detection of cardiac arrhythmias is provided.

9. ECG recorder according to one of the preceding claims, characterized in that the evaluation function for the automatic determination of R-R intervals and, preferably, for the automatic determination of the current-hurry heart rate from the last measured R-R intervals is formed.

10. ECG recorder according to one of the preceding claims, characterized in that the evaluation function is designed for the automatic evaluation of heartbeats, wherein the QRS complex corresponding pattern for a first recognized heartbeat is formed, the similarity of the QRS complex of a subsequent Heartbeat is automatically determined with the pattern and wherein at a specified similarity, a new pattern is formed from the subsequent heartbeat.

11. ECG recorder according to claim 9, characterized in that the evaluation function for detecting cardiac arrhythmias is formed by comparing the determined R-R distances with R-R pattern distances.

12. ECG recorder according to one of the preceding claims, characterized in that a memory function for preferably automatically storing the ECG signal (20) is provided upon detection of a cardiac arrhythmia.

13. ECG recorder according to one of the preceding claims, characterized in that a memory function is designed for automatically timed storing the ECG signal (20) is provided.

14. ECG recorder according to one of the preceding claims, characterized in that a memory blocking function is provided such that when memory blockage no storage of the ECG signal (20) is possible.

15. ECG recorder according to one of the preceding claims, characterized in that the transfer function is designed such that when a cardiac arrhythmia occurs, the ECG signal (20) is automatically transferable to the receiving station, preferably wirelessly via radio and / or infrared and / or wired.

16. ECG recorder according to one of the preceding claims, characterized in that the ECG signal (20) is convertible before transmission into an audio signal, preferably according to the FSK method.

17. ECG recorder according to one of the preceding claims, characterized in that the conversion into an audio signal according to the FSK method is carried out such that at high transmission quality fast transmission and poor transmission quality is provided a slow transmission.

18. ECG recorder according to one of the preceding claims, characterized in that a call number of the receiving station for automatic transmission is deposited.

19. ECG recorder according to one of the preceding claims, characterized in that the evaluation function is designed for automatic detection of ischemia characters in multi-channel ECG sections.

20. ECG recorder according to one of the preceding claims, character- ized in that both an event recording and a long-term ECG monitoring is possible.