WO2008071843A1

WO2008071843A1 - A system, a measuring instrument and a method for measuring the electrocardiogram of a person

Info

Publication number: WO2008071843A1
Application number: PCT/FI2007/050674
Authority: WO
Inventors: Merja Perhonen; Juhani Perhonen
Original assignee: Corusfit Oy
Priority date: 2006-12-11
Filing date: 2007-12-11
Publication date: 2008-06-19
Also published as: FI20065787A0; FI20065787L

Abstract

The invention relates to a system, a measuring instrument and a method for measuring person's electrocardiogram (ECG). The system comprises a monitoring device, a concentrator and measuring instruments connected to the monitoring device via the concentrator. The wearable measuring instrument comprises at least two sensors in an ECG coupling so that the sensors are arranged to measure data on the electrical function of the heart in a determined, substantially stable ECG coupling, irrespective of the activity of the person, and to transmit the data wirelessly to the concentrator. The system also comprises post-analysis offline by means of prognosis models developed for this purpose.

Description

A system, a measuring instrument and a method for measuring the electrocardiogram of a person

Field of the invention

The invention relates to a system disclosed in the preamble of claim 1 for measuring the electrocardiogram of two or more persons. The invention also relates to a measuring instrument disclosed in the preamble of claim 15, as well as to a method disclosed in the preamble of claim 28.

Background of the invention

Rehabilitation of persons, analyses of physical condition and pre- vention of diseases have gained a strong foothold in modern-day life. There are an increasing number of diseases caused by the standard of living, i.e. too small amount of physical exercise and excessive energy intake. Correspondingly, it is possible to affect these diseases by increasing physical exercise and paying attention to the balance between energy intake and energy consumption. Similarly, an increasing number of exercisers are interested in their own health and physical condition, as well as in the effect of keep-fit training on health. Thus, a large number of solutions have been developed for monitoring physical condition, by means of which individuals are able to monitor their per- formance during exercise, as well as their physical and physiological characteristics.

Swedish patent SE 526 576 discloses a system for monitoring a value measured from at least one human body. The system is intended for monitoring the heart rate of exercisers during group exercise. In the system one sensor is attached to the body to measure a value. The sensor is adapted to measure heartbeat at ECG-precision (Electrocardiography), which in the publication means measuring an R-peak. Additionally, a receiver unit is attached to the body, which receives a signal from the sensor. This receiver unit transmits the signal further to another receiver unit located outside the body. The system also comprises a representation unit for representing values graphically.

International patent publication WO 99/30613 discloses a system for monitoring activity. The system is also intended for monitoring several persons simultaneously. A unit measuring heartbeat is attached to the persons' bodies. This heartbeat data is transmitted to a central unit that monitors the persons' physiological state in real-time. The unit attached to the body is a belt fastened on the chest, and it comprises two elec- trades measuring heartbeat.

US patent publication 5,862,803 discloses a system intended for medical monitoring. The system measures the electrocardiogram i.e. ECG of patients wirelessly by means of electrodes when the patient lies still in bed.

Although various systems have been developed for measuring persons' physical characteristics in different kinds of situations, it seems that prior art lacks a system that measures real time ECG signal in chest coupling so the object of measurement may move freely during the measurement. Publications SE 526 576 and WO 99/30613 disclose a system for measuring physiological characteristics of a moving person. Although ECG is mentioned in the publication, reference is thereby made only to heart rate measurement, which takes place by identifying the R-peak during heartbeat. Publication US 5,862,803 discloses ECG measurement in chest coupling, but it is used for measuring the physiological characteristics of a person staying still. For this reason, it is not discussed in the publication how the electrodes remain in their places when the person is moving.

In some situations particularly accurate measurement data regarding the electrical changes occurring in a person's heart is required. Such a situation occurs for example when patients suffering from coronary artery disease are exercising. In the coronary artery disease the coro- nary arteries bringing blood to the cardiac muscle have become clogged and the most common symptoms include effort angina, myo- cardial infarct, arrhythmia and cardiac insufficiency. The coronary artery disease is a significant problem in the USA and in other western countries, but increasingly also in Asia, due to increased overweight and the lifestyle that burdens the heart and the blood vessels. Thus, it is possible to prevent and treat the disease by loosing weight and exercising. Conventional heart rate measurement only reveals the condition of the heart one-sidedly during exercise, and because the strain of coronary artery disease patients must be monitored more extensively, the existing measuring systems are not suitable for this kind of precise measurement. Thus, the purpose of the present invention is to disclose a method that enables real-time monitoring of the condition of persons' hearts in a group for example by ECG measurement in chest coupling or upper arm coupling, substantially simultaneously for all members of the group during exercise, as well as offline examination of the ECG signal to prevent the development and progress of coronary artery disease by means of predictive models produced for this purpose.

Brief Summary of the invention

This purpose can be attained by providing a system, a measuring instrument and a method for measuring the electrocardiogram of a person.

The system for measuring the electrocardiogram (ECG) of two or more persons, which comprises a concentrator, a monitoring device and measuring instruments, is characterized in that

- the concentrator is arranged to collect data on the electrical function of the heart of two or several persons simultaneously, which data is obtained from a wearable measuring instrument of each person, said measuring instrument comprising at least two sensors in ECG coupling so that the sensors are arranged to measure data on the electric function of the person's heart in a determined, substantially stable ECG coupling, irrespective of the person's activity and to transmit the data wirelessly to the concentrator which is arranged to transmit this data identifiably to the monitoring device, and - the monitoring device is arranged to identify the measuring instrument transmitting the data and to monitor and repre- sent the received data and to produce an alarm, in case changes detrimental to the function of the heart are discovered in the data and/or to compare the ratio of the heart rate determined from the person's ECG to determined heart rate zones and to transmit this heart rate data back to the person's own monitoring device or to the exercising equipment used by the person to control the equipment.

The measuring instrument is characterized in that the wearable measuring instrument comprises at least two sensors in ECG coupling so that the sensors are arranged to measure data on the electrical function of the heart in a determined, substantially stable ECG coupling, irrespective of the activity of the person, and to transmit the data wirelessly to the concentrator.

The method for measuring person's electrocardiogram in a system comprising a monitoring device, a concentrator and at least one measuring instrument, is characterized in that in the method data on the electrical function of the person's heart is measured irrespective of the person's activity by means of a wearable measuring instrument comprising at least two sensors in a substantially stable ECG coupling, and said data is transmitted wirelessly to the concentrator that transmits the data identifiably to the monitoring device (120), which monitors and represents the received data and produces an alarm when it de- tects changes detrimental to the function of the heart and/or compares the ratio of the heart rate determined from the person's ECG to heart rate zones determined for the person and transmits this heart rate data back to the person's own monitoring device or to the exercising equipment used by the person to control the equipment. The dependent claims will present some preferred embodiments of the invention.

The solution according to the invention is based on the need to main- tain good quality ECG measurement irrespective of the person's activity. Good quality ECG measurement is attained when the person stays still during the measurement, but the moving of the person, especially physical exercise challenges the production of a good quality ECG signal. For this reason the invention is focused on maintaining the ECG coupling, i.e. keeping the sensors in their places in the determined coupling, especially when a person is moving.

As described above, the measuring instrument comprises at least two sensors. The measurement between two sensors is a so-called bipolar measurement. If there are more than two sensors, one sensor is used as a so-called reference sensor to which the other sensors are compared. In an embodiment of the invention the reference sensor is a sensor placed below the person's other collar bone. In a second embodiment of the invention the reference sensor is placed below the chest. The location of the reference sensor depends on the measurement coupling in use, and thus it may vary.

The invention enables real time ECG measurement of one or several persons, but preferably of more than one person during physical exer- cise. The real time aspect means that the electrical function of the person's heart is measured during physical exercise and this measured data is transferred with as small delay as possible to a collecting unit that transmits the data further to a monitoring computer. The aim is to use as little time as possible for data transmission and analysing the measurement data, wherein it is possible to react to the changes occurring in the electrical function of the person's heart as quickly as possible. In other words, by means of the system according to the invention it is possible to monitor and control person's physical exercise in real-time during the exercise. The invention is developed in view of the exercising safety of coronary artery disease patients and in view of determining and predicting the effect of the exercise. In addition to this, it is possible to utilize the invention when monitoring moving cardiac patients in hospitals, and pos- sibly domestically to collect and store information and to transfer the information to an expert interpreting the ECG, such as a doctor.

Description of the drawings

The invention will be described in more detail with reference to the appended figures, in which

Fig. 1 shows an example of the system according to the invention, Figs 2a to 2d show examples of the results of ECG signal processing, Fig. 3 shows another example of the system according to the invention,

Fig. 4a shows an example of coupling the ECG sensors on the chest,

Fig. 4b shows an example of an ECG sensor,

Fig. 4c shows an example of a wearable measuring instrument according to the invention,

Figs 5a to 5b show in more detail an example of a wearable measuring instrument,

Figs 6a to 6b show another example of positioning the ECG sensors and a wearable measuring instrument, and Figs 7a to 7b show in more detail a second embodiment of the wearable measuring instrument according to the in- vention.

Detailed description of the invention

Before describing the invention in more detail, the applicant would like to specify some terms used in the description. The term "person" refers in this context to a human being or other living creature whose physical characteristics can be measured by means of the system according to the invention. The term "electrocardiogram" i.e. ECG refers to a standard electrocardiogram used in medical examination, but in this invention the term "ECG coupling" can also refer to other standard ECG couplings available at the time of writing this application. Such a diagram shows for example the heart rate, but also other factors affecting the function of the heart, for example the ST level, which indicates the oxygen supply of the cardiac muscle.

The appended drawings show examples of the invention. The sizes, shapes and dimensions shown in these figures may deviate significantly from the actual ones. In addition, it should be noted that figures 4a, 4c, 5a, 5b, 6a, 6b, 7a and 7b show the coupling of the heart sensors in an illustrative way. The locations of the sensors shown in the figures do not necessarily correspond to their natural locations. Furthermore, the locations of the sensors may vary depending on the person and the variable to be measured.

The invention relates to a system that measures the electrocardiogram i.e. ECG of an individual. The following example illustrates the act of measuring the electrocardiogram of an individual during physical exercise, but it is obvious that the invention may also be utilized in other situations, for example when monitoring patients moving in the cardiac wards of hospitals.

One example of the system 100 is shown in Fig. 1 , in which the ECG of more than one exerciser is measured during group exercise. The system can be used for example in a gym so that a group performs so- called circuit training where each member of the group performs his/her own exercise in one exercising equipment and thereafter moves along to the next exercising equipment. There may be more than one, for example two exercisers using one piece of equipment at a time. The radio network of the system has a star topology and in this example it comprises one concentrator 110 and eight measuring instruments 101 to 108, one for each exerciser. The measuring instrument consists of at least ECG sensors, which are positioned against the skin of the person being the target of measurement in a way described hereinbelow. Each measuring instrument 101 to 108 is capable of transmitting two ECG channels at a sampling frequency of 250 Hz, and for example with the resolution of 10 to 16 bits. In addition to the ECG data, each measuring instrument 101 to 108 is capable of transmitting the maximum of four auxiliary channels at low sampling frequency, for example with the resolution of 10 bits. These auxiliary channels may also be used for example to measure battery voltage and/or to transmit sensor-impedance readings. In the system the concentrator 110 collects data measured by the measuring instruments 101 to 108 and transmits the data forward to the monitoring device 120 of the system. The measurement data transmitted by the measuring instrument 101 to 108 does not have to be encrypted, but the identification data of the measuring instrument is transmitted with the data packet. This identification data is used for identifying the exerciser. The identification takes place in the monitoring device 120 of the system in which a user is allocated for the identification data of the measuring instrument. The identification data may be for example an identification number or other data determining the user. The identifying of the person may also be conducted in the monitoring device automatically after coupling the measuring instrument to the system. In this case the measuring instrument comprises for example an RFID by means of which the system identifies the person. In some cases it is also possible to transmit the identification data of the exercising equipment along with the data packet. This enables controlling the exercising equipment by the monitoring device 120 of the system. Personal data of each member of the group and their individual heart rate zones have been stored in the monitoring device 120 of the system. These heart rate zones may be determined by means of an earlier physical fitness test. The monitoring device 120 monitors the changes occurring in the electrical function of the person's heart and the ratio of the measured heart rate to the heart rate zones, and this heart rate data may also be transmitted to the person's own monitoring device (not shown in the figure).

The person's own monitoring device may be a monitoring device positioned for example on the person's wrist or another part of the body, another separate display device or portable electronic display device, such as a mobile phone or a PDA device (Personal Digital Assistant) to which heart rate data determined on the basis of the ECG is transmitted. In addition to the heart rate data it is also possible to produce personal training intervals from the monitoring device of the system to the personal monitoring device.

The system is well suited for monitoring a small group (for example 6 to 10 persons), but the system does not restrict the number of persons in the group. In the system, attention is paid to the way in which it is possible to make the ECG signal produced by the measuring instruments so pure that it may reliably used for monitoring the function of the exerciser's heart. The measuring instruments are also designed in such a manner that by means of them it is possible to reliably monitor a small group without the measuring instruments of the exercisers disturbing each other. The system produces an alarm, if the monitoring device detects for example changes in the ST level or arrhythmia in the ECG data received from a measuring instrument. The monitoring device of the system is used for storing alarm limits for each measuring instrument and each exerciser, on the basis of which the alarm is given. In connection with the alarm, it is shown on the display of the monitoring device which person the alarm relates to and what is his/her electrocardiogram, from which the point causing the alarm is indicated.

In one embodiment the monitoring device of the system controls the exercising equipment used by the person on the basis of the received ECG signal. If the person is working out with an exercise bike, the monitoring device adjusts the resistance so that it is suitable for the heart for example in view of a reduction in the ST level or arrhythmia. In another embodiment the monitoring device does not control the exercising equipment, but gives feedback on the adjustment of resistance in use to the person's own monitoring device or alternatively to the exercising equipment used by the person, for example "reduce speed", "reduce weights" or vice versa, if the efficiency of the workout is too low, for example the heart rate is too low. By means of the monitoring device of the system the instructor of the group may monitor the ECG of the persons during exercise. In this example the monitoring device of the system is a desktop computer, but it is obvious that the monitoring device may also be a portable computer, a portable display or a mobile device, such as a PDA device or a mobile phone. Because of the portable monitoring device the moving of the instructor supervising the workout is not tied to the monitoring device of the system.

Fig. 3 shows another embodiment of the system according to the invention. In the figure group exercisers 301 to 304 perform their own workout for example in the same place, such as a gym. Each exerciser wears a measuring instrument which measures data to be transmitted to the concentrator 110. The concentrator 110 transmits the data further to the monitoring device 120 of the system. In this example the monitoring device is connected to a database 330, which may form a part of the monitoring device 120 or which may be physically located in the same space with the monitoring device or to which it is possible to establish a connection for example via a communication network. The database 330 contains data on the users of the system and group exercisers, monitoring results and any possible necessary data relating to the operating situation of the system. By means of the database 330 it is possible to compare the measurement results of the users of the system in real time with the data in the database and by means of the system it is possible to control the persons' workout and estimate the prognosis of coronary artery disease.

The system stores the data obtained from the person's measuring instrument, which enables monitoring the person's ECG signal to pre- vent development and progress of coronary artery disease by means of prognosis models developed for this purpose.

The measuring instrument used by the group exercisers 301 to 304 may be a wearable measuring instrument, one example of which is described in Fig. 4c. The wearable measuring instrument 420 may be a shirt or a vest type device that comprises sensors in desired locations. The measuring instrument of Fig. 4c comprises two sensors 401 , 403 positioned in couplings V5 403 and reference 401. The number of sensors may also be different from two, as shown in Fig. 4a in which three sensors are positioned in couplings reference 401 , V2 402 and V5 403. The sensors may also be coupled in some other way than that shown in Fig. 4c. Figs 6a and 6b show alternative placement of sensors, in which the reference 401 is positioned below the chest and the ECG electrodes 402 and 403 are placed in person's upper arms.

The sensors are placed so that they are positioned in correct locations in the person's body when the person is wearing the measuring instrument. In addition to the sensors, the measuring instrument 420 may comprise a collecting device 450 that receives the signal to be measured by means of sensors and transmits it to the concentrators wirelessly or through wires. The operation of this collecting device 450 may have also been integrated in the structure of the sensors, wherein the sensors themselves transmit data to the concentrator.

ECG signal processing

The signal processing of the ECG data may be conducted partly in the measuring instrument and partly in the monitoring device. The signal processing may be conducted by means of functions derivateSignals(ecg1 , ecg2), detectQRS(fs, dersum), calculateHR(fs, Rpeaks) and avgComplex(Rpeaks, ecg_signal). The execution of the functions may occur primarily in the monitoring computer, whereas the signal processing in the measuring instrument may involve filtering, amplification and/or sampling of the signal. These functions produce the graphic representations shown in Figs 2a to d in a corresponding manner.

Function derivateSignals(ecg1 , ecg2)

The purpose of the function is to differentiate both ECG channels transmitted by the measuring instrument. The absolute values of the derivatives are taken and the results are summed up. As a result, the function returns a sum vector dersum, from which the QRS complexes can be identified. When the function is called, the ECG signals from the channels 1 ecg1 and 2 ecg2 (Figs 2b and 2c) of the measuring instrument are given as parameters for the function. The diagram illustrating the result of the function is shown in Fig. 2a.

detectQRS(fs, dersum)

The purpose of this function is to recognize the QRS complexes from the sum vector dersum returned by the aforementioned function. In the function, an initial threshold level is first determined, and the points exceeding the same are searched for. These points are windowed and the locations of the maximum values are retrieved therefrom. These maximum values describe the R peak occurring in the cardiogram. Information on the location of the maximum values is stored in an Rpeaks vector, which is eventually returned by the function. The threshold level is constantly updated in accordance with the magnitude of the recognized R-peaks. When this function is called, the sampling frequency fs and the differentiated sum vector dersum obtained from Fig. 2a are given as parameters for the function. The diagram illustrating the result of the function is shown in Fig. 2b. Fig. 2c also shows another measured ECG signal.

calculateHR(fs, Rpeaks)

The purpose of this function is to calculate an average value for the heart rate. When the function is called, the used sampling frequency fs and the vector Rpeaks determined above, indicating the location of the R peaks, are given as parameters for the function. In the function, the lengths of the RR intervals (time between successive RR peaks) and thereby the temporary heart rate values in the form beats/minute are calculated on the basis of successive R peaks. Finally, an average value hr is calculated on the basis of these individual momentary heart rate values, said function returning the average value as a return value.

avgComplex(Rpeaks, ecg_signal)

The purpose of this function is to determine a so-called average value complex. In the function, a sufficiently large number of samples are collected from the environment of each recognized R-peak into a cycles table, and finally an average value complex is calculated on the basis of these samples. When the function is called, the R peaks recognized as parameters are given for the function as an Rpeaks vector, and the ECG signal of the channel from which an average value complex is to be formed, is given as an ecg signal vector. As a return value the function returns an avg_complex table containing this calculated average value complex (120 samples). The diagram showing the result of the function is shown in Fig. 2d. Fig. 2d shows an isoelectric level 201, J point 202 and the change in the ST level ST20 203, ST40 204, ST60 205 and ST80 206. By means of the J point 202 and the change in the ST level 203 to 206, it is possible to identify ischemia (lack of oxygen in the cardiac muscle) and to determine the risk of myocardial infarct.

ECG sensors and their couplings

The system measures the ECG for example from the person's upper body. There are at least two measuring zones in the upper body, and one or several sensors are placed in each of them. In the example of Fig. 4a, the person 302 has three measuring zones, each containing one sensor 401 , 402, 403. In order to attain an ECG level signal, at least two sensors are required, one of which must be a so-called reference sensor 401. This reference sensor 401 may be located for example below person's right collar bone, as shown in Fig. 4a, or be- low the left collar bone. Thus, in addition to the heart rate (i.e. R peak), at least the ST level and the conduction times of the electric signal in different parts of the heart can be found. Other sensors to be used may be placed for example on the same side of the body with the reference sensors, but on the opposite side with respect to the reference sensor. In other words, if the reference sensor is located below the person's right collar bone, the other sensors may be placed on the left hand side of the person's chest. A person skilled in the art is aware of the fact the sensors may also be placed in other locations.

Alternatively, the ECG sensors may be placed on the upper body of the person 302 in so that the reference sensor 401 is positioned below the chest and the ECG sensors 402, 403 are positioned on person's upper arms, as shown in Figs 6a and 6b.

The one or several sensors used in addition to the reference sensor 401 may be placed in coupling points V1 to V6, of which V1 is located in the fourth rib interspace, on the right-hand side of the breastbone; V2 in the fourth rib interspace, on the left-hand side of the breastbone; V3 in the fifth rib interspace, between V2 and V4; V4 in the fifth rib interspace on the central line of the left collar bone; V5 in the front line of the left armpit at the height of V4; V6 in the central line of the left armpit, at the height of V4. If one wishes to measure ECG only with two sensors, it is also possible to select the chest coupling V5 in addition to the reference sensor, wherein sufficient measurement result is obtained. To measure effort ECG of one person, it is possible to use 10 sensors (so-called 12 coupling measurement) in which 6 sensors are used for chest coupling and 4 sensors are placed in limb couplings.

When several sensors (the actual sensor and one or several parallel sensors) are placed in one measuring zone, one of the sensors may produce a signal of different quality than another one. Thus, the system can be arranged to identify the sensor producing the best signal and to monitor the measurement signal produced by the sensor. Furthermore, by measuring sensor-skin impedance, it is possible to determine whether the sensor has sufficient skin contact. Thus, the monitoring device can be adopted to monitor the quality of the signals it has produced and to indicate if a significant weakening of quality takes place. Thus, the contact surface of the sensor to the person's skin can be improved.

In addition to the reference sensor 401 and the measuring sensors (402, 403) it is possible to use a separate ground electrode as a fourth electrode. By means of this it is possible to reduce the movement artefacts showing in the signal.

Fig. 4b shows an example of the sensor 403. The sensor is fixed to the measuring instrument 420 and positioned against the skin 400. It should be noted that Fig. 4b is presented for illustrative purposes only, and differing from Fig. 4b, the sensor may be partly or entirely integrated in the measuring instrument 420. It is possible to apply adhesive gel between the sensor 403 and the skin 400, which improves the ad- hesion of the sensor 403 to the skin 400. Instead of the adhesive gel 413 it is also possible to use other solutions, or the sensor 403 may be constructed in such a manner that it can adhere on the surface of the skin tightly. The sensor may also be a so-called dry sensor, wherein the gel is not needed.

In ways familiar to a person skilled in the art, the ECG can also be measured from other parts of a person's body, such as limbs. The limb sensors may be fastened on both ankles and/or wrists. The use of limb sensors is important for example when the person taking part in the ECG monitoring is a patient suffering from paralysis and being rehabilitated for example by means of a manually pedalled bicycle. Thus, it is possible to measure ECG data from ankles that remain stationary. In the limb coupling the so-called reference sensor may be positioned in the left ankle of the person.

Wearable measuring instrument

As was mentioned above, the persons taking part in the monitoring wear a measuring instrument, one example of which is shown in Fig. 4c. In the vest of Fig. 4c, the sensors have been arranged in the desired chest coupling. For the purpose of implementing the invention, it is important that the wearable measuring instrument fulfils the conditions set by the invention. The measuring instrument must produce a signal of sufficiently good quality when the person stays still or when he/she is carrying out physical exercise. This means that the sensors must remain in the places where they were initially intended. The sensors must not change their place, because then disturbance such as movement artefact may occur in the signal, i.e. low-frequency, but possibly high-amplitude fading in the basic level of the signal caused by the movement of the sensor. The measuring instrument must also preserve its shape, i.e. it must be manufactured of a material that stretches but also reverts to its original size and shape. The measuring instrument must maximize the person's freedom of movement, i.e. it must behave like a normal sports gear, but the sensors and the collecting device attached thereto must also be taken into account.

Figs 5a and 5b show a more detailed example of a wearable measuring instrument 420 comprising a sensor belt 500, which, apart from the fastening point Y, is detachable from the actual measuring instrument 420. The sensor belt 500 is for example made of Velcro® tape, or the like, to which the sensor 403 can be fastened in a detachable manner in the correct location. For the reference sensor 401 the shoulder strap of the measuring instrument must also contain Velcro tape or the like. The measuring instrument 420 also comprises a holder 450 for the collecting device, which is for example a pocket. The holder 450 may also be a strap or the like that can be tightened by means of Velcro tapes. In Figs 5a and 5b the measuring instrument 420 is provided with wire channels 510, 520 for the wires of the sensors 401 , 403 from the sensor to the collecting device. It is possible to produce such a number of wire channels in the garment that cor- responds to the number of sensors necessary and the wire channels are sewn in the fabric, for example in the seams. Instead of wire channels it is possible to use for example a conducting thread, which could be sewn or ironed on the measuring instrument. The wire channel 510 made for the reference sensor 401 can be implemented for example via the neck portion of the garment, wherein the channel does not need to extend for example over a zipper 530. If the measuring instrument is put on by pulling it over the head and it does not comprise a zipper or another fastening element, the wire channel 510 of the reference sensor 401 may run from the front side of the garment to the collecting device. The wires of the sensors may be textile sensors or other corresponding electric conductors.

The purpose of Fig. 5a is especially to illustrate the detachable quality of the sensor belt 500. In Fig. 5a the sensor belt is fastened to point Y in the side seam 420 of the measuring instrument, and its length can be adjusted on the basis of the person's measurements. It is obvious that the, fastening point may also be located elsewhere, for example in the back portion of the measuring instrument, for example in the middle of the back portion. The maximum measurement of the measuring instrument 420 also determines the maximum measurement for the sensor belt 500, but the sensor belt 500 can be tightened to a smaller measurement, wherein it is possible to attain optimal pressure of one or several sensors fastened thereto against the body. As was mentioned above, the sensors fastened to the sensor belt 500 are detachable, wherein their location in the sensor belt can be altered, if the wearable measuring instrument 420 is intended for general use. If the measuring instrument 420 is tailored for one person, the sensors can be fastened to their correct locations in a stable manner. The detachable quality of the sensor belt 500 is important, because it enables fastening of the sensors tightly against person's body, and the tightening of the belt does not show on top of the wearable measuring instrument.

As was mentioned above, the shoulder strap of the wearable measuring instrument may also comprise Velcro tape or the like for fastening the reference sensor 401. In addition to this, it is possible to place cushioning material in the strap, by means of which the pressure of the reference sensor 401 on the person's skin can be improved.

The measuring instrument shown in Figs 5a and 5b comprises a holder 450 for the collecting device on the right-hand side of the wearable element. The location of the holder 450 is selected in this manner so that it would be as close to the sensor 403 as possible. It is obvious that the location of the holder can also be changed on the other side of the chest in the wearable element in accordance with the location of the sensor 403 or irrespective thereof.

Figs 7a and 7b show a second example of a wearable measuring instrument 420. The wearable measuring instrument comprises a detachable sensor belt 500 in which the reference sensor 401 is attached. The wearable measuring instrument, which in this case is a shirt, comprises the ECG sensors 403 and 402 in its sleeves so that the sensors remain in their place and are fastened as tightly as possible on the surface of the skin. For the wires of the sensors, the measuring instrument is provided with wire channels 510, 520 from the sensor to the collecting device.

If the sensors in use are limb sensors to be attached on the ankles, the wearable measuring instrument must be of trouser type. The trousers may also be tights that comply with the contours of the body, or loose sports trousers with a tightening at the ankles (i.e. sensors). The wires coming from the sensors may be hidden in the outer seams of the trousers, and passed therethrough for example to the waist, where the collecting device is located.

The sensors in use may be so-called dry sensors which do not neces- sarily need a gel or other moisturizing agent to produce a good signal from the person's body. During exercise the sensor may get wet because of sweat, which typically improves signal quality.

Examples of embodiments

The following describes, as examples, the function of the system according to the invention in gym environment.

Example 1. For a couple of years a person (51 years old) has suffered from occasional arrhythmia symptoms lasting little over one hour at a time, and the symptoms have increased recently. The arrhythmia has never been medically examined, because the heart rate has suddenly returned to the normal level by itself, but the person has felt himself very tired afterwards. However, the arrhythmia symptoms have restricted for example skiing activities, especially alone, as well as moving in the nature in general, because the fear of arrhythmia and possible need for help has constantly been present.

The person was exercising in a gym where a system according to the invention for measuring the electrocardiogram (ECG) of the person was in use, by means of which system person's real-time ECG could be obtained, and the heart rate data was also determined on the basis of the ECG and sent to the person's display device during exercise. After warming up, the person noticed that the symptoms of arrhythmia arrived and the pulse counter gave a reading 194. The system recognized changes detrimental to the function of the heart in the person's ECG and gave an automatic alarm to the gym instructor. The instructor saw on the monitoring device of the system or on his portable display whom the alarm related to and his electrocardiogram, which also showed the point causing the alarm. The instructor was able to take immediate action and call an ambulance, to tell the ambulance personnel what had happened as well as to provide evidence on the person's electrocardiogram. Thus, the system facilitated the person's access to proper treatment.

Had the system according to the invention not been available, the person could have contacted the gym instructor and told the instructor about the symptoms, wherein the instructor would have called an ambulance after assessing the situation for a while. Because of this delay, the hospital personnel would not have found out about the arrhythmia, because the pulse would have had time to return to the normal level, wherein the person's access to proper treatment would have been delayed.

Example 2.

A person (36 years old) has been exercising extensively, doing for example spinning in various sports centres for several years. However, the gyms have not been able to provide the person with such classes in which the aerobic section would have been sufficiently efficient. The person decided to try out a gym in which the system according to the invention is in use, said system controlling the person's exercise in real time. The exercise was conducted in the gym by means of said system by controlling the heart rate, and the intensity of the exercise was set on the correct level in view of the condition of the person. After the exercise the person was extremely satisfied, because now for the first time after long history of training in gyms, she was aware of the effi- ciency of the exercise. The cardiac training system according to the invention thus enables a heart rate controlled safe training with individual intensity, whose efficiency may also be estimated within the scope of the system.

Summary

The primary target group of the present invention is formed by patients suffering from coronary artery disease or other cardiac or blood-vas- cular diseases or the like, as well as persons belonging to the group at risk of obtaining these diseases, when these persons perform physical exercise containing endurance training and strength training. Other users are instructors supervising physical exercise. The instructor is a person who must be able to supervise all exercisers, both in view of the intensity and safety of the training. Thus, the monitoring of the ECG must be the instructor's responsibility, as the instructor receives possible alarms from the system. The instructor also has the necessary education giving the competence to monitor coronary artery disease patients while they are exercising. Group exercises have been pro- vided with a ready-made training program that takes into account their present condition and health. In the training program training heart rates and movements to be carried out during the group exercise are determined for the exercisers. If necessary, the training program is updated for example once every two months. In this context it is possible to determine the effect of the training program on the health of each exerciser. The persons' ECG signals during the exercise are stored in the system, and they can be used later to prevent the development and progress of the coronary artery disease by means of prognosis models developed for this purpose.

The system enables real-time monitoring and guidance of persons belonging to the group by means of ECG measurement during the exercise. The system is intended especially for real-time measurement of ECG, but the system can also be used for measuring and monitoring heart rate. The method according to the invention can also be applied in so-called Holter research, which means long-term ECG monitoring. Long-term ECG monitoring deviates from the above-described training monitoring in such a manner that ECG is measured during a period of time lasting from several hours to several days. Long-term ECG monitoring may last for 1 to 14 days. A monitoring sequence shorter than this, i.e. shorter than one day, may be called short-term monitoring, and it can be applied especially in hospitals. In a monitoring sequence longer than the long-term ECG monitoring, so-called extended monitoring, the ECG measurement is conducted for more than 14 days. In a long-term and extended monitoring sequence, the person's collecting unit collects data for a desired period of time and it may keep it stored for transfer at a later stage. This transfer at a later stage may take place after the monitoring sequence has been finished, but in some cases it is pos- sible to transfer data from the collecting unit for example daily or in real time basis. Long-term monitoring is suitable for examining heart symptoms during normal daily routines.

The above-described system and the elements relating thereto illus- trate one example of the solution according to the invention. A person skilled in the art understands that the system may also comprise an undefined number of other databases and elements that improve the functionality of the present system. It is obvious that the above-described different embodiments of the invention can be combined to provide various embodiments of the invention, which realize the need according to the invention. Therefore, the above-presented examples must not be interpreted as restrictive to the invention, but the embodiments of the invention may be freely varied within the scope of the inventive features presented in the claims hereinbelow.

Claims

Claims:

1. A system for measuring the electrocardiogram (ECG) of two or more persons, which comprises a monitoring device (120), a concentrator (110), and measuring instruments (101 - 108), which are connected via the concentrator (110) to the monitoring device (120), characterized in that

- the concentrator (110) is arranged to collect data on the electrical function of the heart of two or more persons si- multaneously, which data is obtained from a wearable measuring instrument (101 to 108) of each person, said measuring instrument comprising at least two sensors (401 , 403) in an ECG coupling so that the sensors are arranged to measure data on the electric function of the person's heart in a determined, substantially stable ECG coupling, irrespective of the person's activity, and to transmit the data wirelessly to the concentrator which is arranged to transmit this data identifiably to the monitoring device (120), and - the monitoring device is arranged to identify the measuring instrument (101 to 108) transmitting the data and to monitor and represent the received data and to produce an alarm in case changes detrimental to the function of the heart are discovered in the data and/or to compare the ratio of the heart rate determined from the person's ECG to heart rate zones determined for the person and to transmit this heart rate data back to the person's own monitoring device or to the exercising equipment used by the person to control the equipment.

2. The system according to claim 1 , characterized in that the ECG coupling is a chest coupling, upper arm coupling or limb coupling.

3. The system according to any of the claims 1 to 2, characterized in that the concentrator (110) is arranged to transmit data wire- lessly to the monitoring device (120).

4. The system according to any of the preceding claims, characterized in that said at least two sensors (401 , 403) are arranged to transmit the measured data substantially in real time during the measurement to the concentrator (110).

5. The system according to any of the preceding claims, characterized in that the measuring instrument (101 to 108) comprises a collecting device (450) via which said at least two sensors (401 , 403) are arranged to transmit the data to the concentrator (110).

6. The system according to any of the preceding claims, characterized in that each measurement instrument (101 to 108) transmits identification data of the measuring instrument (101 to 108) to the concentrator (110).

7. The system according to any of the claims 1 to 5, characterized in that the monitoring device (120) is arranged to identify the measuring instrument (101 to 108) automatically when the measuring instrument (101 to 108) is coupled to the system.

8. The system according to any of the preceding claims, characterized in that the measuring instrument (101 to 108) comprises at least three sensors, of which one is a reference sensor (401 ).

9. The system according to claim 8, characterized in that the reference sensor (401) is positioned under the chest and the other two sensors (402, 403) are positioned in the person's upper arms.

10. The system according to claim 8, characterized in that the sensors other than the reference sensor (401 ) are positioned in a chest coupling locations V1 to V6.

11. The system according to any of the claims 1 to 7, characterized in that in a limb coupling the two sensors (401 , 403) are positioned on the person's ankles.

12. The system according to any of the preceding claims, charac- terized in that said at least two sensors (401 , 403) comprise at least one parallel sensor placed substantially in the same coupling location.

13. The system according to claim 12, characterized in that the monitoring device (120) is arranged to monitor the quality of the signals produced by the sensor or the one or several parallel sensors corresponding thereto, and to select the one having the best quality in view of the measurement.

14. The system according to any of the preceding claims, characterized in that the monitoring device is arranged to store the data received from the measuring instrument (101 to 108).

15. A measuring instrument for measuring person's electrocardio- gram (ECG), characterized in that the measuring instrument comprises at least two sensors (401 , 403) in an ECG coupling so that the sensors are arranged to measure data on the electrical function of the heart in a determined, substantially stable ECG coupling, irrespective of the activity of the person, and to transmit the data wirelessly to a concentrator (110).

16. The measuring instrument according to claim 15, characterized in that that measuring instrument is a wearable vest or shirt (420).

17. The measuring instrument according to claim 16, characterized in that the vest or shirt (420) comprises a sensor belt (500) which, apart from the fastening point (Y), is detachable from the vest or shirt (420).

18. The measuring instrument according to claim 16 or 17, characterized in that that the vest comprises a reference sensor (401) placed in the shoulder strap of the vest.

19. The measuring instrument according to claim 17 or 18, characterized in that the sensor belt (500) comprises at least one sensor (403).

20. The measuring instrument according to claim 15, characterized in that the measuring instrument constitutes trousers.

21. The measuring instrument according to any of the claims 15 to 20, characterized in that the measuring instrument (101 to 108) comprises at least three sensors, of which one is a reference sensor (401 ).

22. The measuring instrument according to claim 21 , characterized in that the sensors other than the reference sensor (401) are positioned in chest coupling locations V1 to V6.

23. The measuring instrument according to claims 15 to 17, characterized in that the shirt (420) comprises two sensors (402, 403) positioned in the sleeves of the shirt so that the sensors (402, 403) are positioned on the person's upper arm and the sensor belt (500) comprises a reference sensor (401 ).

24. The measuring instrument according to any of the claims 15 to 23, characterized in that the measuring instrument (101 to 108) comprises a collecting device (450) arranged to receive data from said at least two sensors (401 , 403).

25. The measuring instrument according to claim 24, characterized in that the measuring instrument (101 to 108) comprises a holder (450) for the collecting device.

26. The measuring instrument according to any of the claims 15 to 25, characterized in that the measuring instrument (101 to 108) also comprises at least one parallel sensor for each said at least two sensors (401 , 403).

27. A method for measuring person's electrocardiogram (ECG) in a system comprising a monitoring device (120), a concentrator (110) and at least one measuring instrument (101 to 108), which at least one measuring instrument (101 to 108) is connected to the monitoring device (120) via the concentrator (110), charac- terized in that in the method data on the electrical activity of person's heart is measured irrespective of the person's activity by means of a wearable measuring instrument (101 to 108) comprising at least two sensors (401 , 403) in a substantially stable ECG coupling, and said data is transmitted identifiably to the monitoring device (120), which monitors and represents the received data and produces an alarm when it detects changes detrimental to the function of the heart and/or compares the ratio of the heart rate determined from the person's ECG to heart rate zones determined for the person and transmits this heart rate data back to the person's own monitoring device or to the exercising equipment used by the person to control the equipment.