WO2007014545A2

WO2007014545A2 - Portable ecg device

Info

Publication number: WO2007014545A2
Application number: PCT/DE2006/001282
Authority: WO
Inventors: Markus Riemenschneider; Klaus Bonaventura; Thomas Doerr
Original assignee: Markus Riemenschneider; Klaus Bonaventura
Priority date: 2005-07-30
Filing date: 2006-07-26
Publication date: 2007-02-08
Also published as: WO2007014545A3; DE102005036501A1; DE112006002661A5

Abstract

A portable ECG device (1) is disclosed, comprising a number of electrodes (3, 5, 7, 9, 103, 105, 107, 109), for application to the body of a patient and for recording electrical cardiac signals, a processor unit (231), for derivation of an ECG from the received electrical signals, a memory (25) with a reference ECG stored therein and a comparator unit (233) connected to the memory (25) for receiving the reference ECG and to the processor unit (231) for receiving the ECG derived from the electrical signals which can compare the derived ECG with the reference ECG. An individual ECG for the patient is stored as reference ECG.

Description

Mobile ECG device

The present invention relates to a mobile ECG device.

In many Western industrial nations, diseases of the heating circulation system are at the top of the disease process. Coronary heart disease is one of the leading causes of death. For example, several hundred thousand people in Germany suffer from a heart attack each year. The medical follow-up after such a heart attack makes a regular check of the heart activity over a longer period necessary. Likewise, heart disease or precautionary measures may require repeated monitoring of cardiac activity over an extended period of time.

During the course of cardiac activity, a sequence of electrical discharges is generated periodically, forming a regular but complex waveform. From this waveform, it can be seen whether the cardiac activity is normal or if there is a deviation from normal cardiac activity. Monitoring cardiac activity therefore typically involves monitoring and recording the waveform. For this purpose, electrodes are placed on the body, which measure skin potentials, which are subject to fluctuations in function of the heart activity. The recorded waveform is commonly referred to as an electrocardiogram or ECG for short. In order to be able to monitor the heart activity over a longer period of time in patients with cardiac diseases, they are portable

Cardiac monitoring systems have been developed. Such a system is described for example in US 6,073,046. The portable described there

ECG device is equipped with a number of electrodes which are attached to the body of the patient and the electrical influenced by the heart

Measure potentials. The recorded potentials are collected and forwarded to a central facility, where, for example, a doctor can assess the patient's ECG.

From EP 0 965 115 B1 a mobile telephone is known, on the back of which four electrodes are arranged, which can be placed on the chest of a human and with whose help electrical potentials of the heart are detected, from which an ECG is derived. The derived ECG is then forwarded to an emergency center, where decisions are made based on the received ECG.

In both cases, a transfer of the ECG is provided to an emergency center where it is evaluated by medically trained personnel.

In particular, when monitoring is to take place, a constant assessment of incoming signals must be made basically. If there is no permanent monitoring and the device such as in

EP 0 965 115 B1 is to be used as an emergency call device, the patient must decide for himself whether he should use the device in order to trigger an emergency call. However, it is not always easy for the patient to recognize whether an acute danger situation exists for him. On the other hand, if he recognizes the danger situation, it may already be too late for successful treatment. An early detection or early warning, for example, includes the request to see a doctor, is therefore possible only with a more or less permanent monitoring, which, as described above, is associated with great effort. The object of the present invention is therefore to provide a mobile ECG device which makes it possible to check the cardiac activity triggered by a patient and is able to recognize a dangerous situation and be used flexibly.

This object is achieved by a mobile ECG device according to claim 1. The dependent claims contain advantageous embodiments of the invention.

An inventive mobile ECG device comprises:

A number of electrodes adapted for application to the body of a patient and for receiving electrical signals of the heart,

a processor unit configured to derive an ECG from the received electrical signals,

a memory with a reference ECG and stored therein

a comparison unit connected to the memory for receiving the reference ECG and to the processor unit for receiving the ECG derived from the electrical signals, configured to compare the derived ECG to the reference ECG. The comparison unit can be realized as a hardware module or as a software module.

In the mobile ECG device according to the invention, an individual ECG of the patient is stored in the memory as a reference ECG.

The mobile ECG device according to the invention makes it possible to detect changes in cardiac activity early on the basis of the comparison of the currently derived ECG with the stored individual reference ECG and thus provide a basis for the early issuance of a cardiac output Warning, for example, in the form "Please look for a doctor to spend. Because the reference ECG is an individual ECG of the patient, the mobile ECG device allows the patient's medical history to be taken into account when compared to the derived ECG. Although the ECGs of healthy people have substantially the same course, heart disease can lead to changes in the ECG that would be normal for the sick patient, whereas for a person with normal heart activity, they would give reason to visit a doctor. If, instead of the individual ECG, a standardized ECG were stored as a reference ECG, the mobile ECG device would hardly be usable in people with pre-existing conditions of the heart because it would constantly produce warning messages that the patient does not need. With an individual ECG of the patient as a reference ECG, such unnecessary alerts can be avoided, so that the device is more flexible than if it contained a standardized reference ECG.

The mobile ECG device according to the invention thus offers, in particular, the possibility of monitoring the heart activity of a patient without transmitting the ECG to a central station, where it is examined by medically trained personnel taking into account the patient's previous history. Thus, a significant reduction in the cost of monitoring the cardiac activity of a patient can be achieved.

In an advantageous embodiment, the mobile ECG device comprises a classification unit connected to the comparison unit for receiving the comparison result, which is configured to classify the comparison result into one of at least two classes to which an item of information may be assigned. The classification unit can also be designed as a software module or as a hardware module. Possible information here in particular the information "reaction required" or "no reaction required" in question. In this embodiment, the mobile ECG device further comprises one with the classification unit for receiving the classification result connected signal generator, which is designed to output the associated information in the case of a predetermined classification result. One of the possible signals may in particular be a request to visit a doctor and may be output, for example, visually or acoustically. If the classification unit has more than two classes into which the comparison result can be classified, a gradual warning of the patient is also possible, for example "find a doctor at the next opportunity", "seek out a heart specialist immediately", etc

In addition, if the mobile ECG device has a writing unit connected to both the processor unit and the memory, and there is also a triggering element connected to the writing unit and externally operable, which is designed to write when actuated trigger the current ECG as a reference ECG in the memory by the writing unit, the stored in the memory reference ECG can be updated at any time. In this way, it is possible to respond appropriately to changes in the clinical picture of the patient. It is not necessary to specify a reference ECG stored once. The writing unit can be designed as a hardware module or as a software module.

To output information to the patient, the ECG device may be equipped with an output device, such as an LCD monitor, on the front side. A brief summary of the findings or a warning message can be displayed on this monitor. In addition, the ECG device may have a back with four electrodes, which is designed to be placed on the chest of the patient. The patient can then simply place the device on the chest with the back of the device and press a shutter button to record an ECG. The simple and uncomplicated handling that is possible with it increases the comfort of the patient when creating an ECG and reduces the number of possible sources of error. D

In addition or as an alternative to the four electrodes on the rear side, the mobile ECG device can have a connection for connecting an electrode cable, with at least 4 electrodes. The use of the electrode cable increases the possibilities of using the ECG device and, in particular, allows operation in a coronary mode in which it is possible to detect circulatory disturbances of the heart. Preferably, the processor unit is equipped with an algorithm which is designed to derive a so-called 12-channel ECG from the signals of the four electrodes. Using the 12-lead ECG, a more detailed analysis of the heart condition is possible than with simple so-called 1-channel ECG or a 3-lead ECG.

In an advantageous embodiment, the ECG device also includes a communication interface, which is designed for wireless or wired communication with other devices. The wireless communication can take place, for example, on protocols such as Bluetooth, WLAN, etc. As a wired interfaces, for example, parallel interfaces or USB interfaces in question. In particular, the communication interface allows communication with computers or personal digital assistants (PDAs), as well as communication with a modem to transmit a derived ECG to a location with trained medical personnel. The latter may in particular be desired if the comparison with the reference ECG reveals that a doctor should be visited and the doctor should be informed in advance that the triggering ECG is to be sighted.

In a further embodiment of the mobile ECG device, the reference memory comprises a database in which personal ECG data of the patient are stored. In the database, for example, the ECGs of the past days can be stored, so that a doctor can get an overview of the course of the medical history of the last days by sifting the ECGs stored in the database. In particular, the mobile ECG device may also include at least two memory or database areas assigned to different patients can be. It then has a switching device which enables a switching of the access by the comparison unit from the one memory or database area to the other memory or database area. Thus, a separate reference ECG can be stored for a number of patients. The mobile ECG device can then be used by several patients at the same time to monitor the heart activity. The memory or database areas can here be embodied as objectively separate memories or databases or as logically separate memories or databases, for example in the form of different sections of the same memory or the same database.

Further features, properties and advantages of the present invention will become apparent from the following description of an embodiment with reference to the accompanying figures.

Fig. 1 shows an inventive ECG device in a perspective view.

FIG. 2 shows the rear side of the mobile ECG device shown in FIG. 1.

Fig. 3 shows the internal structure of the ECG device according to the invention as a block diagram.

Fig. 4 shows the structure of the microcontroller of Fig. 3 in the form of a block diagram.

An embodiment of the mobile ECG device according to the invention is shown in Fig. 1 in a perspective view. The back of the mobile ECG device 1 is shown in FIG.

On the back of the device 1 four electrodes 3, 5, 7, 9 are arranged. The electrodes 3 to 9 essentially form the corners of a square ö

and represent attachment electrodes which are placed on a patient's chest for routine examination or complaints.

The front of the mobile ECG device is equipped with an input device in the form of, for example, a keypad 11 and an output device in the form of, for example, an LCD monitor 13. The keypad 11 is for operating the device, the monitor 13 for outputting an examination result after performing an ECG recording and issuing a warning message, if necessary.

Furthermore, the mobile ECG device 1 is equipped with a connection 15 to which a cable with external electrodes can be connected, for example, by means of a connector. Like the device 1 itself, the cable only needs to have 4 electrodes and allows greater freedom in placing the electrodes on the body. More details are given below.

The mobile ECG device 1 further comprises a communication interface 17, which enable communication of the device with other devices, such as a PC, a PDA, etc. In the present embodiment, the wireless communication interface 17 is designed as an infrared interface, but it may alternatively be designed, for example, as a Bluetooth interface, WLAN interface, DECT interface, GSM interface, etc .. The design as an interface for a wired communication, for example as a USB interface, serial interface, parallel interface, etc, is possible. If a routine examination is to be performed or if chest discomfort occurs, the device with the four attachment electrodes 3 to 9 can be placed on the chest and a start button on the keypad 11 can be actuated. Pressing the start button will trigger the recording of an ECG and its interpretation. The interpretation result is finally output on the monitor 13. Depending on the interpretation result, a warning message may also be issued. The device 1 can be equipped with several operating modes. For example, there may be a mode in which only cardiac arrhythmias are judged. In this case, the apparatus can be used alone with the four rear electrodes 9 to 13. It is preferably still another mode, the so-called coronary mode, available, in which also circulatory disorders can be assessed. In this mode, the electrode cable is used with the at least four external electrodes. To record an ECG in coronary mode, apply the electrodes to the back of the neck and chest and then press the shutter button on the keypad 11.

During evaluation and interpretation of the recorded ECG, the heart rate is displayed on the monitor 13. After the internal

Evaluation is completed, the respective result and, if necessary, a recommendation appears on the monitor. This recommendation may, for example, "No special finding, therefore no action needed", "Please visit a doctor at the next opportunity", "Please see a cardiologist as soon as possible", etc.

The internal structure of the mobile ECG device 1 according to the invention is shown in FIG. 3 in the form of a block diagram. This shows in a highly schematic representation of the electrodes 3, 5, 7, 9 on the back of the device 1 and a connected electrode cable with four external electrodes 102, 105, 107 and 109. The device further comprises an ECG amplifier 19, an A. / D converter 21, a microcontroller 23 and a nonvolatile memory 25, for example in the form of an EPROM, an EEPROM, a flash EPROM, etc., and a RAM memory 27, that is, a memory with random access.

The ECG amplifier 19 is connected to the electrodes 3, 5, 7, 9 or 103, 105, 107, 109 for receiving the signals measured by them. It amplifies the signals of the electrodes and outputs them to the A / D converter 21 Next, which converts the previously analog signals into digital signals. The digital signals are finally read out by the microcontroller 23, which performs the evaluation and interpretation of the potentials picked up by the electrodes. For this he accesses stored in the non-volatile memory 25 reference data, which represent a reference ECG. As a reference data or reference ECG, an EKG recorded by the patient at an earlier time is stored here in the non-volatile memory.

It should also be noted at this point that the non-volatile memory may include a database with a number of prior findings of the patient. In addition, the database or the non-volatile memory may be divided into several memory areas that are assigned to different patients. For example, the non-volatile memory may contain reference ECGs for multiple patients and, if appropriate, previous findings from these patients. This can include other important data such as blood type or other diseases or the like.

The RAM memory 27 serves only as a working memory for the microcontroller 23.

The internal structure of the microcontroller is shown in FIG. 4 in the form of a block switch. The microcontroller 23 comprises a processor unit 231 which reads out the output signals of the A / D converter, a comparison unit 233 connected to the processor unit 231 and a classification unit 235 connected to the comparison unit. The described structure can be realized as a hardware structure of the microcontroller. Preferably, however, it is realized in the form of software modules.

Advantageously, the microcontroller 23 also comprises a writing unit 237 and as a triggering element, for example, via the keypad 11 to be actuated trigger circuit 239. The writing unit 237 and the trigger circuit 239 are designed to actuate the .

Trigger circuit 239 to write a new reference ECG in the non-volatile memory 25. The trigger circuit 239 is executed in the present embodiment in the form of a push button eg. On the keypad 11. If the input device 11 and the output device 13 are implemented in the form of a touchscreen, the triggering element can also be realized via the touchscreen by means of a suitable software module. The writing unit 237 may, for example, be designed as a hardware component of the microcontroller 23. Preferably, however, it is implemented as software. In order to write a new reference ECG in the non-volatile memory 25, this is at least partially designed as a programmable read-only memory, in particular as electrically erasable and programmable read-only memory EEPROM (electrical erasable p_rogrammable read only memory). Alternatively, however, other forms of programmable read-only memory may be used. The use of a programmable read-only memory as a non-volatile memory 25 also allows updating the software of the ECG device and the database with the patient data.

The ECG device may also include a filter (not shown) that removes or suppresses interferences such as noise or artifacts due to muscle tensions in the analog or digital signals. The filter can also be implemented as a hardware component or realized in the form of a suitable filter software.

To evaluate the data recorded by the electrodes 3, 5, 7, 9 or 103, 105, 107, 109, the processor unit 231 reads out the digital ECG data from the A / D converter 21. It serves as the central control unit of the microcontroller 23. The comparison unit 233 receives from the processor unit 231 the derived ECG. It also receives the individual reference ECG from the nonvolatile memory 25 and compares it to the derived ECG. The comparison result is forwarded to the classification unit 235 which, according to various, in particular, medical criteria, places it in one of at least two classes divides. The classes are associated with various information to be displayed on the display element 13 or notifications.

The classification in the classification unit 235 takes place in particular on the basis of medically relevant criteria, which may be given for example by certain parameters of an ECG or by a specific course of the ECG. One of the classes into which the comparison result can be classified is that the comparison between the derived ECG and the reference ECG does not provide any medically relevant findings. Otherwise, the comparison result is classified into the other class, which stands for a medically relevant finding, which causes the microcontroller 23 to issue a warning message, for example, "Please see a doctor at the next opportunity," on the display element 13. Of course, even then if the comparison result in the class representing no finding is classified, an output is made on the display unit 13, for example, "No particular finding".

The processor unit 231 in the microcontroller 23 is equipped in particular with an algorithm which determines a so-called 12-channel ECG from the signals recorded by the four electrodes 103, 105, 107, 109 of the electrode cable by scaling and combining them. To enable the deriving of the 12-lead ECG from the signals from the four electrodes 103, 105, 107, 109, they are attached to the back of the neck of the patient and to his chest such that the electrode positions represent the tips of a tetrahedron. in the center of which is the heart. The described method for deriving a 12-channel ECG from the signals of the four electrodes 103, 105, 107, 109-and in particular the arrangement of these four electrodes-makes it possible to derive the 12-channel ECG from the signals of the four electrodes. without having to have another electrode providing a reference potential. The processor 231 is also formed in the present embodiment for deriving a so-called vector ECG from the signals of the four electrodes 103, 105, 107, 109 of the electrode cable. In a vector ECG, the potential differences are treated as if they were generated by an electric dipole, which is in place of the heart. An electric dipole represents a directional quantity that can be described in the form of a vector. During a cardiac cycle, both the magnitude and orientation of the cardiac vector vary. In a vector ECG, the components of the heart vector are now determined over a heart cycle, for example in a Cartesian coordinate system in which all coordinate axes are perpendicular to one another. The information about the heart activity is then in the fluctuations of the vector components over a cardiac cycle.

The interpretation of a vector ECG is equivalent to the interpretation of a conventional 12-lead ECG, as it is today mostly used as a stationary device in cardiology practices or in hospital, and therefore provides an alternative to interpretation based on a classic 12-channel ECG. For an overview of different ways to derive ECGs, see US 4,850,370, which is referred to in this regard.

It should be noted at this point that the comparison of the recorded ECG with the reference ECG and the interpretation of the comparison result in the ECG device according to the invention can be carried out on the basis of the vector ECG data. Determining the 12-lead ECG is not absolutely necessary. However, the 12-lead ECG makes it easier for a physician to interpret the ECG data because it is similar to conventional cardiac or hospital-derived ECGs.

Claims

claims

A mobile ECG device (1) comprising a plurality of electrodes (3, 5, 7, 9, 103, 105, 107, 109) adapted for mounting on the body of a patient and for receiving electrical signals of the heart, a processor unit (231) adapted to derive an ECG from the received electrical signals, a memory (25) having a reference ECG stored therein, and one to the memory (25) for receiving the reference ECG and to the processor unit (231) for receiving the ECG derived from the electrical signals associated comparison unit (233), which is configured to compare the derived ECG with the reference ECG, characterized in that as a reference ECG an individual ECG of the patient is stored.

2. Mobile ECG device (1) according to claim 1, characterized by - one with the comparison unit (233) for receiving the

Comparison result connected classifying unit (235) configured to classify the comparison result into one of at least two classes; and an output unit (13) connected to the classification result representing unit (235) for outputting a message in case a predetermined classification result is designed.

3. A mobile ECG device (1) according to claim 1 or 2, characterized by a writing unit (237) which is connected both to the processor unit (231) and to the memory (25) and connected to the writing unit (237) and externally operable trigger member (239) adapted to be actuated to trigger the writing of the currently derived ECG as a reference ECG in the memory (25).

4. Mobile ECG device (1) according to one of claims 1 to 3, characterized in that it comprises a front side with an output device (13).

5. Mobile ECG device (1) according to one of claims 1 to 4, characterized in that it comprises a back with four electrodes (3, 5, 7, 9), which is designed for placement on the chest of a patient.

6. Mobile ECG device (1) according to one of claims 1 to 5, characterized by a connection for connecting an electrode cable having at least four electrodes (103, 105, 107, 109).

7. A mobile ECG device (1) according to claim 5, characterized in that in the processor unit (231) an algorithm for deriving a 12-channel ECG from the signals of the four electrodes (103, 105, 107, 109) is implemented ,

8. Mobile ECG device (1) according to one of claims 1 to 7, characterized by a communication interface (17).

9. Mobile ECG device (1) according to one of claims 1 to 8, characterized in that the memory (25) comprises a database with personal ECG data.

10. Mobile ECG device (1) according to one of claims 1 to 9, characterized in that the memory (25) or the database comprises at least two memory areas or database areas that can be assigned to different patients and that a switching device is present, switching the access by the comparison unit (233) from the one memory or database area to the other memory or database area.

11. Method for deriving a 12-channel ECG from the signals of four electrodes (103, 105, 107, 109), in particular in a mobile one

ECG device (1) according to one of claims 1 to 10, characterized by

Combining and scaling of the electrodes (103, 105, 107,

109) recorded signals, characterized in that the

Electrodes (103, 105, 107, 109) are attached to the back of the neck and on the chest of a patient so that they

Corners of a tetrahedron form in the center of the heart of the

Patient lies.