Device and method for detecting a medical active implant located inside a subject

Abstract

A device and a method for detecting a medically active implant for electrical stimulation located inside a person are described. Furthermore, the use of the device for determining the operating state of the medically active implant is set forth. The device is characterized by the following components: a) at least two electrodes in electrical contact or capable of electrical contact with the person, b) a voltage measurement unit, which is electrically connected to the at least two electrodes and is capable of generating a voltage time signal, and c) an evaluation unit connected to the voltage measurement unit, which comprises the following components: a unit for deriving a power density spectrum on the basis of the voltage time signal measured between the at least two electrodes; a unit for determining local maxima in the power density spectrum and the so-called peak frequencies respectively assigned to the local maxima; a unit for deriving the least common multiple of the determined peak frequencies; a comparator unit, which carries out a data comparison on the basis of the derived least common multiple, which corresponds to the stimulation frequency of the medically active implant, and information stored in a reference database and generates a comparison result; and a signal unit in communication with the comparator unit, which generates a signal depending on the comparison result.

Description

TECHNICAL FIELD

[0001] The invention relates to a device and a method for detecting a medical active implant for electrical stimulation located inside an individual. Furthermore, the use of the device for determining the operating state of the medical active implant is described.

[0002] In more and more areas of medicine, active implants for treating different diseases are used. In contrast to purely passive implants, which typically have purely mechanical support and bearing functions, active implants comprise electronic components, which are able to detect electrical signals primarily for supporting organ functions and to generate electrical signals for stimulation purposes and to apply them locally.

[0003] The presence of the active implant can thus be inferred to the presence of the corresponding clinical indication. In emergency situations of a patient, the knowledge of the clinical indication of the implanted active implant is required for a change of the emergency treatment. For this reason, it is important that the medical staff learns from the already existing active implant also in cases where the patient himself cannot be interrogated anymore. BACKGROUND

[0004] A patient with a medical active implant is handed over an implant certificate according to article 18 paragraph 2 of the European Medical Devices Regulation, by which the corresponding implant can be identified. Thereby, as long as the patient can inform about the implant and / or carries the certificate with him, information about the implant can be provided.

[0005] The publications US 2006 / 0 293 714 A1, US 4 291 703 A, US 5 406 955 A and US 9 788 756 B2 each disclose a device and a method for detecting a medical implant. SUMMARY

[0006] It is the task of the invention to give a device and a method for detecting a medical active implant for electrical stimulation located inside an individual, by which in a non-invasive manner it can be quickly, reliably and without the need of communication with the individual determined whether an active implant is present and, if so, which implant is involved. In particular, it should be achieved that the proven implant is identified according to its stimulation pattern and the operating state of the implant is judged.

[0007] The solution of the task of the invention is given in a device according to the invention. The subject of the subsequent technical solutions is the use of the device for identifying and determining the operating state of the implant. The subject of the further technical solution is a method according to the solution.

[0008] The features of the invention concept which are further improved in an advantageous manner are known from the content of the description, in particular from the embodiments shown with reference to the drawings.

[0009] The device for detecting a medical active implant for electrical stimulation located inside an individual according to the solution has at least two electrodes in electrical contact or capable of electrical contact with the individual, a voltage measuring unit, which is electrically connected with the at least two electrodes and is capable of generating a voltage time signal, and an evaluation unit connected with the voltage measuring unit, by means of which the presence and the kind or type of the active implant can be derived on the basis of the measured voltage time signal. To this end, the evaluation unit comprises a unit for deriving a power density spectrum on the basis of the voltage time signal measured between the at least two electrodes, which is preferably in the form of a spectrum analyzer. Furthermore, a unit for determining local maxima within the power density spectrum and the so-called peak frequencies respectively assigned to the local maxima is used, and a unit for deriving a least common multiple at the determined peak frequencies. Finally, the evaluation unit comprises a comparator unit, which carries out a data comparison on the basis of the derived least common multiple, which corresponds to the stimulation frequency of the medical active implant, and information stored in a reference database, and generates a comparison result, and a signal unit in communication with the comparator unit generates a signal from the comparison result.

[0010] The measurement theory on which the solution is based essentially consists in carrying out a voltage measurement between at least two skin surface areas of the individual which are determinedly predefined and in analyzing the voltage signal obtained thereby temporally and spectrally. In addition to the use of adhesive electrodes which can be placed on the skin of the individual, electrodes which are attached by means of temporary negative pressure are also suitable, as are the electrodes which are used in conjunction with standard EKG devices.

[0011] The contact areas suitable for the voltage measurement are preferably the head region, the neck region, the upper body region, the groin region or the leg region, in particular preferably along the known equipotential surface of the excitation potential of the heart.

[0012] The at least two electrodes applied to the individual are electrically, i.e. line-supported, connected with a voltage measuring unit, which is placed inside a structural unit as a separate component or as an integrated component part, the structural unit also comprising an evaluation unit, which is composed of a plurality of components for spectrally investigating and evaluating the detected voltage time signal. The structural unit can be integrated as a module plug-in in an existing medical diagnostic device or designed as a portable unit for manual on-site use.

[0013] The voltage time signal detected by means of the voltage measuring unit is detected with a scan frequency fs of at least 100 Hz, preferably with a scan frequency of between 1 MHz and 1 Ghz and is preferably stored in a memory unit. In said memory unit or in a further memory unit information stored in the form of a reference database is furthermore stored for data comparison.

[0014] For digitally signal processing and storing the analog voltage time signal provided by the voltage measuring unit, the analog voltage time signal is converted by means of an analog-digital converter into a digital signal which is transferred to an evaluation unit, the individual components of which are realized essentially on the basis of digital signal processors and / or microcontrollers.

[0015] The evaluation unit is thereby provided with a unit for deriving a power density spectrum as a first component, which represents the spectral power density of the power of the voltage time signal with respect to the frequency in a possible frequency range between 0 and fs / 2.

[0016] After deriving the power density spectrum, the spectral positions of the local maxima in the power density spectrum are determined in a second component, a so-called unit for determining local maxima, which are each characterized by a so-called peak frequency. Possible criteria for determining the local maxima are, for example, that the power density of the spectrum decreases by, for example, 3 dB around the peak frequency within a determined frequency width, for example, 2 Hz.

[0017] In the case of the peak frequencies which have been derived in advance, a least common multiple is also determined at least at the majority of the derived peak frequencies by means of a third component of the evaluation unit, a so-called unit for deriving a least common multiple, which corresponds to the stimulation frequency of the medical active implant in the individual. The amplitude of the stimulation frequency and of all harmonics of the stimulation frequency are also stored in the memory unit for continued processing and continued information access.

[0018] If the least common multiple cannot be derived at the determined peak frequencies, this can be evaluated as an indication that no active implant is present in the individual or that an already present implant is not activated or does not function properly. In this case, the unit for deriving the least common multiple generates a signal which can be displayed on a display in a form coded accordingly by means of a signal unit, in order to inform the physician or the user of the device accordingly.

[0019] If, on the contrary, a smallest common denominator can be derived at the determined peak frequency, this is taken as an indication of the presence of an active implant which stimulates in the body at the measured stimulation frequency. By means of a further component, a so-called comparator unit, which is arranged in the structural unit, a data comparison is carried out on the basis of at least the derived stimulation frequency and by means of information stored in a reference database, which leads to a comparison result, in accordance with which a signal is generated which can be perceived visually, acoustically or haptically by means of a signal unit, whereby the user is informed not only about the presence of an active implant and the operating state of the active implant, but also about the kind or type of the active implant and thus possibly the underlying clinical indication. Preferably, the signal unit is designed as a display for displaying alphanumeric characters.

[0020] By means of a suitable classification of the information stored in the reference database, for example according to the definition of error-free or error-affected states and of general or implant-specific tolerance ranges, it is additionally possible to ascertain the operating state of the medical active implant when the presence of the medical active implant has been confirmed.

[0021] In order to improve the load capacity of the kind or type determination of unknown implants, further information is taken into account in an advantageous manner, which can be derived from the measured and, if necessary, stored voltage time signal and compared with corresponding information stored in the reference database by means of the comparator unit. Suitable as additional information, for example, is the entire curve of the measured voltage time signal and information which can be learned or derived therefrom about the stimulation pulse characteristics of the medical active implant, for example stimulation pulse shape, stimulation pulse width, stimulation pulse symmetry, stimulation pulse number, stimulation pulse amplitude and temporal sequence and stimulation pulse time correlation with respect to the heartbeat.

[0022] From the time curve of the power density spectrum in the range of the determined stimulation frequency and its higher harmonics, a typical stimulation pattern can also be extracted respectively and compared with suitable reference data. If the active implant is, for example, a cardiac pacemaker, the stimulation pattern associated therewith is characterized by short stimulation pulses which are synchronized with the heartbeat. If, however, the active implant relates to an activator for lowering blood pressure, the stimulation signal associated therewith is characterized by a stimulation signal which occurs very continuously in time. In a further preferred embodiment, the voltage unit is electrically connected with at least three electrodes which are placed on different regions on the skin surface of the individual. By the possibility of measuring at least three voltage time signals thereby achieved, the location determination of the medical active implant inside the individual can be carried out by means of triangulation measurement. The evaluation unit for this includes a triangulation unit which carries out the location determination of the medical active implant on the basis of the measured voltages between the at least three electrodes.

[0023] Preferably, all components of the evaluation unit, i.e. the unit for deriving the power density spectrum, the unit for determining the local maximum within the power density spectrum, the unit for deriving the least common denominator, the unit for deriving the stimulation pulse characteristic and the comparator unit in the form of a digital signal processor or microcontroller, the functionality of which is respectively pre-defined by software-based evaluation rules and determination rules.

[0024] According to a further embodiment of the device according to the solution, an interface is provided, through which the voltage time signal can be directly transmitted from the EKG device to the evaluation unit and used for detecting and identifying active implants possibly located inside the individual. In this case, the electrodes are part of the EKG device. It is also conceivable that the device according to the solution takes over the complete measurement and detection of the electrocardiogram of the individual by corresponding supplementation by the EKG measurement unit, so that the detection and identification of possible active implants can be carried out on the basis of the EKG voltage time signal during the implementation of a standard EKG monitoring. BRIEF DESCRIPTION OF DRAWINGS

[0025] The application is described below by way of example with reference to the drawings without limiting the general inventive concept. In the drawings:

[0026] Figure 1 A schematic diagram of a device for detecting and identifying medical active implants according to the solution is shown. DETAILED DESCRIPTION

[0027] Figure 1 A structural unit B is shown, which can be implemented in the form of a modular plug-in unit inserted into a medical rack or as a portable, easily operable functional unit.

[0028] The device is connected with at least two electrodes E1, E2, which can however be arbitrarily extended to n electrodes, which are respectively designed for releasable secure placement on the skin surface of a person.

[0029] For detecting the voltage between the electrodes E1, E2, a voltage measurement unit 1 is provided in the structural unit B, which detects the potential difference between the electrodes E1, E2 time-resolved and generates a voltage time signal S. The analog voltage time signal S is converted into a digital voltage time signal by means of an analog-digital converter A / D, which is not only transmitted to an evaluation unit 2, which is part of the structural unit B, but also to a memory unit (7) for further evaluation or analysis.

[0030] The unit 3 for deriving the power density spectrum is arranged within the evaluation unit 2, in which a spectral analysis of the measured voltage time signal S is carried out by processor support to obtain the power density spectrum PSD. The evaluation unit 2 also comprises a unit 4 for determining local maxima within the power density spectrum PSD, to which the so-called peak frequencies P are assigned, respectively. In a further unit 5, a least common multiple is derived for the determined or derived peak frequencies P, which corresponds to the so-called stimulation frequency f.

[0031] Within the framework of the comparator unit 6, a comparison is carried out on the basis of reference data RD stored in a memory unit 7 and at least the derived stimulation frequency f in order to obtain a comparison result VE. Alternatively, the comparator unit 6 can be provided with further information in order to carry out the comparison, which can be extracted from the voltage time signal S or the digitized voltage time signal, such as the pulse shape of the stimulation pulses of the medical active implant, the pulse symmetry of the stimulation pulses, the pulse width, the pulse amplitude, the pulse number, the pulse time sequence and the time correlation of the stimulation pulses with the heartbeats. Corresponding reference data are stored in the memory unit for carrying out the comparison for the further information.

[0032] The comparator unit 6 generates a signal Sx from the comparison result VE, which is transmitted to a signal unit 8, which is realized in such a way that it can be perceived visually, acoustically and / or haptically from the signal Sx. Preferably, the signal unit 8 is a display, by means of which information about the discovered active implant and its operating state as well as possible clinical indications in the form of alphanumeric characters can be displayed.

[0033] List of reference signs

[0034] B structural unit

[0035] 1 voltage measurement unit

[0036] 2 evaluation unit

[0037] 3 unit for deriving the power density spectrum

[0038] 4 unit for determining local maxima within the power density spectrum

[0039] 5 unit for deriving the least common multiple of the determined peak frequencies

[0040] 6 comparator unit

[0041] 7 memory unit

[0042] 8 signal unit

[0043] PSD power density spectrum

[0044] P peak frequency

[0045] f stimulus frequency

[0046] RD reference data

[0047] VE comparison result

[0048] Sx result signal.

Claims

1. A device for detecting an active medical implant capable of electrical stimulation located within an individual, comprising: - at least two electrodes in electrical contact or capable of electrical contact with said individual, a voltage measuring unit electrically connected to the at least two electrodes and capable of generating a voltage-time signal, An evaluation unit connected to the voltage measuring unit, the evaluation unit comprising the following components: - a unit for deriving a power density spectrum (PSD) based on a voltage-time signal measured between said at least two electrodes, a unit for determining local maxima within the power density spectrum (PSD) and the so-called peak frequencies P respectively assigned to these local maxima, - means for deriving a lowest common denominator of at least some of the determined peak frequencies P, a comparator unit that performs a data comparison based on the determined lowest common denominator and information stored in a reference database and generates a comparison result, the lowest common denominator corresponding to the stimulation frequency of the medically active implant, and - a signaling unit in communication with the comparator unit, the signaling unit generating a signal in dependence on the comparison result.

2. The device according to claim 1, characterized in that The electrodes are designed as skin contact electrodes.

3. The device according to claim 1 or 2, characterized in that The electrodes are standard EKG electrodes.

4. The device according to claim 1 or 2, characterized in that The unit for deriving the power density spectrum (PSD) is a spectrum analyzer.

5. The device according to claim 1 or 2, characterized in that The voltage measuring unit is connected to an A / D converter for obtaining a digitized voltage-time signal, the output of which is connected to an evaluation unit designed in the form of at least one digital signal processor or microcontroller.

6. The device according to claim 5, characterized in that The evaluation unit comprises a memory unit in which at least a digitized voltage-time signal can be stored.

7. The device according to claim 1 or 2, characterized in that The evaluation unit comprises a unit for determining information that can be derived from the voltage-time signal and relates to stimulation pulses, which can be generated with the aid of an active medical implant and include at least one of the following information: stimulation pulse shape, stimulation pulse symmetry, stimulation pulse width, stimulation pulse amplitude, number of stimulation pulses, time sequence of stimulation pulses, and time correlation of the stimulation pulses with the heartbeat.

8. The device according to claim 6, characterized in that The comparator unit compares the voltage-time signal stored in the memory unit and / or information derived therefrom with information stored in the reference database, which corresponds to voltage-time signals of known medical implants and / or information derived therefrom.

9. The device according to claim 6, characterized in that The comparator unit carries out a functional pattern comparison between the stored voltage-time signal and / or information derived therefrom and a voltage-time signal of a known medical implant and / or information derived therefrom.

10. The device according to claim 1 or 2, characterized in that The signal unit is a visually and / or audibly perceptible signal unit.

11. The device according to claim 1 or 2, characterized in that The voltage measuring unit is electrically connected to at least three electrodes, and the evaluation unit comprises a triangulation unit which performs a position determination of the medically active implant based on the voltages measured between the at least three electrodes. 12 . Use of the device according to claim 1 for detecting an unknown active medical implant for identifying the active medical implant.

13. Use of the device according to any one of claims 1 to 11 for determining the operating state of an active medical implant by comparing the voltage-time signal stored in the memory unit and / or information derived therefrom with classified information stored in a reference database, the classified information relating to the error-free or error-prone state of the implant, the definition of general or implant-specific tolerance ranges.

14. A method for detecting a medically active implant in an individual, characterized in that A combination of the following method steps: - performing voltage measurements by means of at least two electrodes in electrical contact with the individual to respectively obtain a voltage-time signal, - performing a spectral analysis of the measured voltage-time signal to obtain a power density spectrum, - determining local maxima within the power density spectrum (PSD) and the so-called peak frequencies P respectively assigned to these local maxima, - determining the lowest common denominator of the determined peak frequencies (P), which corresponds to the stimulation frequency of the medical active implant, - comparing the stimulation frequency with reference data to obtain a comparison result, and - identifying said medically active implant based on said comparison result.

15. The method according to claim 14, characterized in that Based on the voltage-time signal, information is derived, which relates to stimulation pulses, which are generated with the aid of the active medical implant and include at least one of the following information: stimulation pulse shape, stimulation pulse symmetry, stimulation pulse width, stimulation pulse amplitude, number of stimulation pulses, time sequence of stimulation pulses, and time correlation of stimulation pulses with the heartbeat.

16. The method according to claim 15, characterized in that Information derived from the voltage-time signal is compared with reference data to obtain a comparison result, which is used to identify the medical implant.

17. The method according to any one of claims 15 to 16, characterized in that Information derived from the voltage-time signal is compared with reference data to obtain a comparison result, which is used to determine an operating state of the medical active implant.

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