WO2005094673A1

WO2005094673A1 - Medical chest belt

Info

Publication number: WO2005094673A1
Application number: PCT/EP2005/002995
Authority: WO
Inventors: Gerold Schwarz; Marc Weitl
Original assignee: Energy-Lab Technologies Gmbh
Priority date: 2004-03-22
Filing date: 2005-03-21
Publication date: 2005-10-13
Also published as: DE102004013931A1; EP1776038A1

Abstract

The invention relates to a medical chest belt comprising a signal detection unit for detecting electrical signals on a body surface, two electrodes which face the chest, are non-adhesive, and are provided with a reinforcement layer that is electrically conductive on the side facing the body and is capable of absorbing and eliminating water, as well as a reference electrode located on the rear face. Said reference electrode is embodied so as to cover a large area and in a flexible manner such that moisture eliminated by the body accumulates between the reference electrode and the body while creating low transition resistance between the body and the reference electrode.

Description

description

Medical chest strap

The present invention relates to a medical chest strap for detecting electrical signals on a body surface.

Electrical signals on a surface of the body, especially the human body, indicate the electrical spread of stimuli in the heart and its stress and health status. In the clinical area, the electrical voltages on the body surface are recorded by a series of electrodes on the chest as well as on the arms and legs.

An electrocardiogram is then the temporal registration of the time-varying electrical vector from the heart on the surface of the body. Characteristic voltage levels or depths of an electrocardiogram are identified by letters. The absolute levels of these tensions, their time intervals, as well as their steepness and duration play a decisive role for medical interpretation. Many pathological changes in the heart can be diagnosed from these parameters and also, e.g. during exercise, strain on the heart.

Furthermore, the electrical signal curve allows an analysis of the heart rate variability. This can also be done

Recognize stressful conditions or the general condition of the heart or body. Particularly in the fitness area, for example to adapt a training situation, it is desirable to record the stress situation for the heart or for the body of the athlete.

However, standing medical arrangements for detecting electrical signals on the body or athlete's surface are rather unsuitable. They require complex wiring and the attachment of suitable, mostly adhesive electrodes on the body. As a result, however, movement is sometimes restricted and sporting activities are impaired. Such arrangements are therefore unsuitable in the field of wide sports.

Although an electrode belt is known from EP 1 090 583 A1, by means of which the heartbeat rate can be detected, the detection of more complex electrical signals on a body surface is not possible. Accordingly, an electrode belt is provided, which is worn around the chest of the athlete and has two electrodes.

With electrodes arranged in chest straps, the particular difficulty lies in achieving good contact between the body surface and the electrode and at the same time not significantly restricting the movement of the athlete and thus creating a high level of comfort. In order to be able to determine real stress states or stress states of the test person, the signal quality must also be consistently high even during intensive sporting movement.

US 4,122,843 discloses a belt with three disc-shaped rubber electrodes, which can be used to record electrocardiograms. One of the three electrodes is provided as a reference electrode. Good contact between body and surface and electrodes is achieved here by a particularly high pressure with which the electrodes are pressed onto the surface of the body, which can impair comfort.

It is therefore an object of the present invention to provide a medical chest strap for detecting electrical signals on a body surface, the signal quality being sufficiently high over a wide range of application conditions, in particular when the user is exercising, to determine a heart stimulation curve , The chest strap should also be extremely comfortable to wear and can be used in a variety of ways.

According to the invention the object is achieved by a medical chest strap according to claim 1.

Accordingly, a medical chest strap is provided with a signal detection device for detecting electrical signals on a body surface, which has two breast-side electrodes, preferably with a high input resistance, and a back-side reference electrode. The electrodes on the breast side are non-adhesive and have a reinforcing layer with an electrical conductivity on the side facing the body, the reinforcing layer being capable of absorbing and releasing water. The reference electrode is of such a large and flexible design that moisture emitted by the body accumulates between the reference electrode and the body and thus one creates low contact resistance between the body and the reference electrode.

The idea on which the invention is based is to largely suppress interference and noise in the electrical signals by means of the reference electrode on the back. The combination according to the invention of the two breast-side electrodes, which have a high input resistance, with the back-side reference electrode allows the detection of complete heart excitation curves of the belt wearer.

The use of the breast-side electrodes has the advantage that when the wearer of the medical chest belt moves, the reinforcement layer releases water or moisture and thus suppresses a triboelectric effect. This considerably improves the signal quality, since interference due to electrical charging caused by the movement or friction between electrodes, chest strap material, wearing clothes and / or the body is greatly reduced.

According to an advantageous embodiment, the back-side reference electrode has a large area and is flexible and has conductive material. Due to the flexible design, the reference electrode on the back hugs the body of the wearer and thus ensures improved wearing comfort. As a result, it can have a large area, and it can easily be inserted into the medical chest strap according to the invention during the production process.

The embodiment of the reference electrode according to the invention has the advantage that, even in the case of clothing between the chest strap and the body surface, moisture between the reference electrode trode and the body arises, which increases the conductivity of the path between the reference electrode and the electrical signals on the body surface and thus creates better signal quality. In a particularly preferred embodiment, the reference electrode has carbon-impregnated silicone.

In a further advantageous embodiment of the medical chest strap, the chest strap has neoprene. Neoprene is a versatile material used in the fitness area, which is easy to work with, is water-repellent and offers a high level of comfort.

In a preferred embodiment, the electrodes on the breast side can be plugged onto the chest belt. This makes it easy to remove and replace the breast electrodes if they are defective or to be replaced by electrodes from other manufacturers. The chest strap according to the invention can thus also be used with adhesive electrodes.

Advantageously, the electrodes in the medical chest strap according to the invention are arranged in such a way that, when the chest strap is attached to the body, the breast electrodes on the left and right of the breastbone (sternum) rest on the lower costal arches, and the back reference electrode lies at least on one of the back muscles Spine. This arrangement according to the invention has the decisive advantage that, particularly in the case of female wearers, the wearing comfort is particularly high because the chest area is not covered by the belt. In addition, the position of the reference electrode on a muscle strand that offers a soft contact surface is advantageous because so the reference electrode is particularly well nestled and thus creates a particularly low contact resistance between the body and the reference electrode. In a preferred development of the medical chest strap according to the invention, the signal detection device has a differential amplifier which outputs an electrical voltage between the two breast-side electrodes, the potential of the back-side reference electrode serving as the reference potential. The use of the potential of the rear reference electrode as a so-called virtual ground largely eliminates interference from interference fields and increases the signal quality.

In a further advantageous development of the medical chest strap according to the invention, the signal detection device has an analog-digital converter for digitizing the electrical voltage and for outputting digital data. Furthermore, an evaluation device for analyzing the digital data is advantageously provided, the evaluation device providing an evaluation result. The evaluation device particularly advantageously creates a heart portrait. A heart portrait is a colored three-dimensional representation of an electrocardiogram and signals the condition of the heart muscle and the intensity of the stress load on the heart being tested.

In yet another advantageous development of the medical chest strap according to the invention, a transceiver for wireless transmission of the digital data or the evaluation result to an external receiving device is provided. This transceiver is advantageously a Bluetooth transceiver. The evaluation device is advantageous coupled to the transceiver and executes external commands received from the transceiver. The differential amplifier, analog-digital converter, transceiver and / or the evaluation device are preferably arranged between the breast-side electrodes.

It is particularly advantageous if the breast-side electrodes are arranged symmetrically around the signal detection device resting on the breastbone and are coupled to the differential amplifier via lines of the same length in each case. This symmetrical placement minimizes the distance to the respective breast-side electrode and is less prone to errors. Since the back-side reference electrode is used as a virtual ground, a longer connection path to it does not significantly interfere.

In a further embodiment, the chest strap has a diagonal shoulder strap which is fastened at a point adjacent to the front of the body and at a point adjacent to the back of the body on the circumference of the chest strap. Such a diagonal strap improves wearing comfort and, at the same time, provides better protection against slipping and rubbing on the body surface for increased signal quality.

The chest belt circumference is advantageously composed of at least two modules which can be connected to one another. As a result, parts, in particular modules, which carry the detection device or electrodes can be exchanged. Further advantageous refinements and developments of the invention are the subject of the dependent claims and the description with reference to the drawings.

The invention is explained below with reference to the exemplary embodiments given in the schematic figures. It shows:

Figure 1 is an exemplary representation of the chest strap.

2 shows a reference electrode on a body;

Fig. 3 is a block diagram of a signal detection device;

Fig. 4-5 voltage curves, which are recorded with different electrode combinations; and

Fig. 6 shows another embodiment of the chest strap.

1 shows a medical chest strap 1, which is made, for example, of neoprene, has a width of about 3 cm and has the length of a typical chest circumference. A buckle 8 is provided for width adjustment. In order to achieve the preferred positions of the electrodes on the circumference of the wearer's chest, as described above, further buckles for width adjustment, for example on the side of the body, can also be provided. The belt can also be made of very elastic material, so that the advantageous positions are achieved by "distorting" the belt. Particularly preferred embodiments have a belt material that is multi-layered and enables wiring between the layers to be protected against external influences for evaluation. lead electronics. In addition, for example, a "double" version of the belt material has the advantage that parts of the signal detection device can be inserted in a pocket.

The belt is widened on the front side of the medical chest belt 1, that is to say the side which lies against the wearer's chest, in order to accommodate parts of the signal detection device 20. When the chest belt 1 is worn, the widened area 21 lies on the breastbone of the wearer. To the left and right of the widened area 21, which is used below as a reference, two breast-side non-adhesive electrodes 2, 3 are provided, which are arranged approximately 12.5 cm from the widened area 21. The chest electrodes 2, 3 lie on the lower rib arches of the wearer when the chest belt 1 is put on. These are non-adhesive electrodes that have a particularly high input resistance.

The widened locations 21 are preferably designed as a pocket that enables the signal detection device 20 to be removed easily.

The two breast electrodes are circular with a diameter of approx. 30 mm and have a male push button half on the side facing away from the body surface, which is spherically shaped. The chest strap is made of two layers and has a 22mm slot at the points for the chest electrodes, which opens into a circular recess or opening of 8mm diameter. The slots are made parallel to the length of the belt. The position of the chest strap material, which forms the outside, i.e. does not rest on the body surface, indicates the sitions of the breast-side electrodes 2, 3, where the circular openings of the inner layer of the belt are, each have a female push-button half, which couples with the male push-button half of the respective electrode and establishes an electrical connection. Cables 19 are attached to the push buttons for connection to the signal detection device 20. The electrodes are easy to replace and yet their arrangement is fixed to the chest strap by the push button positions. The electrical connection via push buttons is also robust and easy to manufacture.

The rear-side reference electrode 4, which is preferably made of carbon-impregnated silicone, is arranged opposite the widened point 21. The reference electrode is about 2.5 cm wide, about the width of the belt, and about 10 cm long. This large-area carbon-impregnated silicone reference electrode 4 lies with the chest strap on the back of the wearer on the muscle strands on the left and right of the spine.

The reference electrode 4 and the two chest electrodes 2, 3 are each connected to the signal detection device 20 with a shielded cable 17, 18, 19 with a line cross section of approximately 0.2 mm ² . The wiring 17, 18, 19 can also be done with a simple and preferably shielded microphone cable.

The large-area reference electrode 4 is firmly sewn to the material of the chest strap, for example neoprene or another fabric. The breast-side electrodes 2, 3 are arranged on push buttons, which can simultaneously establish an electrical connection with the wiring 18, 19. Fig. 2 shows the operation of the back-side reference electrode 4. Due to the flexible and large-scale design of the reference electrode 4, which rests on a body surface 6 of a body 7, moisture 5, for example by perspiration of the wearer during athletic movement, between the electrode and the Body accumulates. In particular, if the reference diode 4 is made of a water-impermeable plastic, for example silicone, the moisture 5 which is emitted by the body through the body surface 6 collects and leads to a particularly low contact resistance between the body 7 and the reference diode 4. As Carbon, which is introduced into the plastic, is particularly suitable.

While many common straps or electrodes have carbon fibers because they are flexible and can be woven into fabric structures, the supposed disadvantage of rubber-like or silicone-containing carbon-impregnated electrodes is advantageously used. The moisture and vapor impermeability provides the required electrical properties of the system of electrode, body surface, moisture and / or clothing in between.

The reference electrode is alternatively composed of several parts, for example two carbon-impregnated silicone electrodes of about 80x40mm, which are attached to the belt so that they rest on the corresponding muscle strands.

Alternatively, an electrode made of carbon fabric can be used, which is itself integrated in the belt structure. A strip of about 250x40mm is then placed on the back of the belt between the ends of the remaining belt terials sewn, riveted or otherwise attached. In the case of riveting, the rivets can advantageously also serve as a connecting element between the electrode material (for example carbon fiber fabric or the aforementioned silicone electrode) and the wiring. Contact through riveting is particularly hard-wearing.

3 shows a block diagram of a preferred embodiment of the signal detection device 20.

The signal detection device 20 has a differential amplifier 9, to which the breast-side electrodes 2, 3 are coupled, the potential of the reference electrode 4 serving as a so-called virtual ground as the reference potential.

The differential amplifier 9 supplies an amplified electrical voltage to an analog-digital converter 10, which digitizes the electrical voltage and outputs it as digital data 11 to an evaluation device 12.

The evaluation device 12 is coupled to a memory 22, which can be a flash RAM, for example. The evaluation device 12 supplies an evaluation result 13, which is transmitted wirelessly 15 to an external reception device 16 via a transceiver 14.

The differential amplifier 9 receives the very weak electrical signals from the breast-side electrodes 2, which are referenced to the potential of the reference electrode 4, amplifies them and forwards them to the analog-digital converter 10. The input signals are typically in the range of less than one millivolt. The differential amplifier 9 raises these signals to a level of approximately one volt, so that these can be processed by the analog-digital converter 10.

The analog-to-digital converter 10 digitizes the data supplied by the differential amplifier 9, preferably with a resolution of 12 bits and a sampling rate of approximately 500 to 1000 samples per second. In order for these data to be considered reliable, the sampling rate should be at least 200 times the respective heartbeat rate. From about 120 samples per heartbeat, an analysis of the heights and the course of the heart stimulation curve is possible.

The digitized data 11 are processed by the evaluation device 12 and, if appropriate, stored in a buffer 22. Since the evaluation device 12 is coupled to the transceiver 14, it can also execute external commands which were transmitted wirelessly to the transceiver 14 by an external receiving device 16. The evaluation device 12 can for example be designed as a digital signal processor or have a programmable processor.

For example, the evaluation device 12 delivers a so-called heart portrait or the corresponding digital data as the evaluation result 13. A heart portrait visualizes the

Conduction of the heart muscle in the form of a three-dimensional colored animation. The corresponding method for displaying the electrical signals or the electrocardiogram is protected by the applicant as a European patent EP 1 047 987 B1.

In particular, the evaluation device 12 can be designed as a digital signal processor that receives the digital data 11 first filters and carries out noise discrimination. The ECG signal obtained in this way can now also be transmitted wirelessly directly to an external receiving device 16 by means of the transceiver 14, or can already be evaluated in the form of the aforementioned heart portrait in the signal detection device 20 and then transmitted to an external receiving device 16 via the transceiver 14 become. In addition, commands can also be sent from the outside wirelessly via the transceiver 14 to the evaluation device 12, which then provides, for example, only the raw ECG data or pre-evaluated data. The transmission of data is therefore bidirectional.

The determination and evaluation of stress parameters requires a particularly high signal quality or quality of the electrocardiogram data. Therefore, the combination according to the invention of the breast-side electrodes 2, 3 and the back-side reference electrode 4 is particularly critical.

In investigations by the applicant, a combination of so-called Hi-Q bioelectrodes from the Canadian manufacturer Advanced Bioelectric Corporation as breast-side electrodes 2, 3 and a flexible, large-area carbon-impregnated silicone electrode as rear-side reference electrode 4 have proven to be particularly advantageous.

However, the chest strap can also be equipped with other commercially available chest electrodes. According to the invention, an input amplifier or differential amplifier with a particularly high input resistance compensates for a poorer contact resistance between the respective electrode and the body surface. A ratio of over about 20: 1 of input wi- the state of the differential amplifier on the contact resistance of the breast electrodes in a chest belt according to the invention provides signals of heart excitation curves which are suitable for further processing according to the invention. A typical input resistance is approx. 70 megohms.

FIG. 4 shows a heart excitation curve of a test person (4A: resting test person, 4B: test person in motion), the curves being recorded on dry skin with two breast-side Hi-Q bioelectrodes and a reference electrode made of carbon-impregnated silicone.

FIG. 5 shows a heart excitation curve of a test person with damp skin (5A: resting test person: 5B: test person in motion), which was recorded with the same electrode combination as in FIG. 4.

4 and 5 it can be seen that the signal-to-noise ratio when the skin is moist, e.g. due to the sweaty wearer during sporting activities, is higher than when the test person is at rest. Although in both cases (FIGS. 4A, 5A and 4B, 5B) additional interference signals occur due to the movement, for example due to triboelectric effects or the effect of the body or the wiring of the electrodes as an antenna for interference fields, for example mobile radio or radio or other transmitters, the signal quality is sufficient to represent the characteristics of a complete heart stimulation curve.

In particular, the use of the Hi-Q bioelectrodes (see also WO 02/065905 AI) reduces interference with the signals due to the triboelectric or frictional electrical effect that occurs when electrodes are applied to the body surface. and slip and at the same time there is a high contact resistance. This is suppressed in the use of the Hi-Q bioelectrodes according to the invention in that the corresponding breast-side electrodes 2, 4 have a reinforcement layer with an electrical conductivity on the side facing the body, the reinforcement layer being capable of absorbing water and giving off water. When the electrodes and thus also the reinforcement layer move, water is released towards the body surface 7 and good contact is established between the body 7 and the electrode 4.

Furthermore, the use of the back-side reference electrode 4, which likewise prevents a triboelectric effect, since a moisture layer 5 forms between the electrode 4 and the body 7, improves the signal.

It is only because of the arrangement and selection of electrodes with a high input resistance and the use of a reference electrode on the back that electrical signals can be recorded on the body surface that provide a complete heart stimulation curve.

Until now, such ECG data could only be recorded using adhesive electrodes, which had to be attached to the body with great difficulty. However, since the medical chest strap according to the invention has non-adhesive electrodes, use in the fitness area in particular is only possible. The chest strap according to the invention can also be worn over sports clothing with a high degree of wearing comfort and yet detects electrical signals with sufficiently reliable quality, as a result of which the stress level or stress level of the heart or the athlete during the training of an athlete can be assessed overall. Compared with commercially available heart rate monitor belts of the inventive medical chest strap allows an improved control and monitoring of the Ge ^¬ sundheitszustandes of the carrier.

FIG. 6 shows a further preferred embodiment of the chest belt according to the invention.

A diagonal shoulder strap D is provided, which is attached to a point D1 adjacent to the front of the body and to a point D2 adjacent to the back of the body of the chest strap. The diagonal strap is more comfortable because it is stretched over one of the wearer's two shoulders and tells the wearer that the belt cannot slide down. The diagonal strap is sewn on, interwoven or connected to the base belt with any fastener that clings to the circumference of the body.

In the preferred embodiment, the base belt consists of three modules A, B, C, which can be connected to one another and thus form the circumference of the chest belt.

A first module carries the signal detection device 20 with the corresponding electronics or the transmission device, transceiver, analog-digital converter, evaluation device and differential amplifier as well as the appropriate power supply.

A second module B carries a first breast electrode 3 and the large-area reference electrode 4 with appropriate wiring. The transition Y or the link Y (not explicitly shown here) between the modules A, B can, for example, as can happen with a push-button combination, ^¬ tallhaltige snaps me the electrical connection Zvi ^¬ rule electrodes 3, 4 and the wiring and the signal detection apparatus 20 in the module A be produced. Other usual plug connections are also possible. Likewise, the belt carrier material can be connected with Velcro fasteners or other conventional buckles or connecting means.

A third module C between the first module A and the second module B closes the belt. The second breast electrode 2 is provided in or on or on the third module C. A connection X, Y, Z between the modules A, B, C is indicated schematically here by a dashed line. Snap fasteners, Velcro fasteners, buckles or buttons are only examples of possible connection means.

Although the present invention has been described above on the basis of a preferred exemplary embodiment, it is not restricted to this but can be modified in a variety of ways.

For example, the medical chest strap is not limited to the dimensions shown in FIG. 1. The use of a chest strap according to the invention is not limited to the human medical field, but can also be used in animals whose stress or fitness or state of health is to be monitored.

The chest strap according to the invention does not have to have the Hi-Q bioelectrodes mentioned. Any type of non-stick electrodes can be used which has a sufficient electrical property, namely a frictional electrical one Effect suppresses and provides a good contact property with the body surface.

The breast electrodes can also consist of sensors with extremely high input resistances that detect an electrical potential even up to a few cm from the body, as described in "Remote detection of human electro-cephalograms and ultrahigh input impedance electric potential sensors" by CJ Harland, T.D. Clark, R.J. Prance in Applied Physics letters volume 81 (2002), pp. 3284 is reported.

The transmission technology of the transceiver is not limited to Bluetooth, but numerous other methods for wireless data transmission, such as ZigBee and radio frequency carriers are possible.

The analysis of the ECG data does not have to be in the form of a heart portrait, but other methods for determining stress parameters, for example from the analysis of the heart rate variability, are also conceivable.

Furthermore, the modules of the chest strap in the modular embodiment can be adapted to any desired division.

LIST OF REFERENCE NUMBERS

1 medical chest strap

2, 3 electrode

4 reference electrode

5 moisture

6 body surface 7 body

8 width adjustment

9 differential amplifier

10 analog-to-digital converters

11 digital data 12 evaluation device

13 Evaluation result

14 transceivers

15 wireless transmission

16 receiving device 17, 18, 19 wiring

20 signal detection device

21 broadening

22 Storage A, B, C belt modules D diagonal belt

X, Y, Z connection

Dl, D2 connection points

Claims

claims

1. Medical chest strap (1) with a signal detection device (2, 3, 4, 20) for detecting electrical signals on a body surface (6) with: two breast-side electrodes (2, 3), which are non-adhesive and one Have reinforcing layer with an electrical conductivity on the side facing the body, the reinforcing layer being water-absorbent and water-dispensing; a rear-side reference electrode (4), which is designed to be so large and flexible that moisture (5) emitted by the body (7) accumulates between the reference electrode (4) and the body (7) and a low contact resistance between the body (7 ) and the reference electrode (4) creates.

2. A medical chest belt (1) according to one of the preceding claims, that the reference electrode (4) has carbon-impregnated silicone.

3. A medical chest strap (1) according to one of the preceding claims, that the chest strap has neoprene.

4. Medical chest belt (1) according to one of the preceding claims, characterized in that the chest strap has a fabric.

5. A medical chest strap (1) according to one of the preceding claims, that the breast electrodes (2, 3) can be plugged onto the chest strap.

6. Medical chest strap (1) according to one of the preceding claims, because the reference electrode (4) is sewn to the chest strap.

7. Medical chest belt (1) according to one of the preceding claims, characterized in that the electrodes (2, 3, 4) are arranged such that the breast-side electrodes (2 , 3) rest on the left and right of the sternum (sternum) on the lower costal arches and the back-side reference electrode (4) lies at least on one of the muscle strands to the side of the spine.

8. Medical chest belt (1) according to one of the preceding claims, characterized in that the signal detection device (2, 3, 4, 20) has a differential amplifier (9) which has an electrical voltage between the two breast electrodes (2, 3) outputs increased, the potential of the back-side reference electrode (4) serves as a reference potential.

9. Medical chest belt (1) according to claim 8, characterized in that the differential amplifier (9) has an input resistance which is at least 20 times a contact resistance between a breast-side electrode and the body surface.

10. Medical chest belt (1) according to claim 8 or 9, characterized in that the signal detection device (2, 3, 4, 20) has an analog-to-digital converter (10) for digitizing the electrical voltage and for outputting digital data (11) ,

11. The medical chest strap (1) according to claim 10, which also means that the analog-to-digital converter (10) samples and converts the electrical voltage at a sampling rate of at least 120 times a heartbeat frequency.

12. A medical chest belt (1) according to claim 10 or 11, characterized in that the signal detection device (2, 3, 4, 20) has an evaluation device (12) for analyzing the digital data (11) and the evaluation device (12) has an evaluation result ( 13) supplies.

13. A medical chest belt (1) according to claim 12, that the evaluation device (12) creates a heart portrait.

14. Medical chest belt (1) according to any one of claims 10-13, characterized in that the signal detection device (2, 3, 4, 20) has a transceiver (14) for wireless transmission of the digital data (11) or the evaluation result (13) to an external receiving device (16).

15. Medical chest belt (1) according to claim 14, so that the transceiver (14) is a Bluetooth transceiver.

16. Medical chest belt (1) according to any one of claims 10-15, characterized in that the differential amplifier (9), analog-digital converter (10), transceiver (13) and / or the evaluation device (12) between the breast electrodes ( 2, 3) are arranged.

17. A medical chest belt (1) according to one of the preceding claims 14-16, that the evaluation device (12) is coupled to the transceiver (14) and executes external commands received from the transceiver (14).

18. Medical chest belt (1) according to one of the preceding claims, characterized in that the breast-side electrodes (2, 3) are arranged symmetrically around the signal detection device (20) and via lines of the same length (18, 19) to the differential are more strongly (9) coupled.

19. Medical chest belt (1) according to one of the preceding claims, characterized in that the chest strap has a diagonal shoulder strap (D) which is attached to a point (D1) adjacent to the front of the body and to a point (D2) adjacent to the back of the body (D2) of the chest strap.

20. A medical chest belt (1) according to one of the preceding claims, that the chest belt circumference is composed of at least two modules (A, B, C) that can be connected to one another.