Electrotherapy device

1. An implantable electrotherapy device comprising:

a housing which has an electrode line connection for the connection of at least one electrode line which is to be placed intracardially and which has at least one measuring electrode for recording an intracardiac impedance signal;

an activity sensor, arranged in the housing, which is adapted to produce an activity level signal whose respective activity level signal values in the implanted condition of the therapy device depend on a physical activity of a patient;

an impedance or conductivity measuring unit, arranged in the housing, which is adapted to produce a unipolar or bipolar impedance or conductivity signal by measuring an impedance or conductivity value between a neutral electrode and a measuring electrode or between two measuring electrodes; and

an evaluation unit, arranged in the housing, wherein the evaluation unit is connected to the impedance or conductivity measuring unit and the activity sensor and is adapted for evaluating the impedance or conductivity pattern signal produced by the impedance or conductivity measuring unit and the respectively time-associated activity level signal and for producing and delivering a contractility signal, in such a way that the contractility signal is derived from the impedance or conductivity signal and the activity level signal and reflects the respective contractile state of a heart associated with an activity level signal value,

wherein the electrotherapy device is adapted to produce a respective time-sampled impedance or conductivity pattern signal and a time-sampled activity level signal associated in respect of time with the respective impedance or conductivity pattern signal, and

wherein the evaluation unit is adapted to form a reference signal pattern from at least one impedance or conductivity pattern signal in dependence on simultaneously recorded activity level signal values, and

wherein the evaluation unit is further adapted to standardize the contractility signal or a contractility signal difference pattern with a respective time-associated activity level signal value or an activity level signal value difference.

2. The electrotherapy device as set forth in claim 1 , wherein the housing includes a neutral electrode and the impedance or conductivity measuring unit is adapted to produce a unipolar impedance or conductivity signal by measuring an impedance or conductivity value between a neutral electrode and a measuring electrode and that the evaluation unit is adapted to derive the contractility signal from the unipolar impedance or conductivity signal.

3. The electrotherapy device as set forth in claim 2 , wherein the evaluation unit is adapted to evaluate the contractility signal as a contractility difference signal in dependence on the impedance or conductivity pattern signal by forming a difference between two impedance or conductivity pattern signals recorded in different periods of time, in such a way that a respective contractility difference value of the contractility difference signal depends on an area which the two impedance or conductivity pattern signals detected at different periods of time include between them.

4. The electrotherapy device as set forth in claim 3 , wherein the evaluation unit is adapted to associate with a respective contractility difference value an activity level signal value which applies for at least one period of time which is associated with at least one of the impedance or conductivity pattern signals.

5. The electrotherapy device as set forth in claim 1 , wherein the evaluation unit is adapted to form the reference signal pattern by averaging of a plurality of impedance or conductivity signal patterns.

6. The electrotherapy device as set forth in claim 5 , wherein the evaluation unit is adapted, for forming the reference signal pattern by averaging, to take account only of those impedance or conductivity signal patterns with each of which there is associated in respect of time a respective activity level signal value below a predetermined limit activity level value.

7. The electrotherapy device as set forth in claim 6 , wherein the electrotherapy device is designed in such a way that a respective period of time over which a respective impedance or conductivity pattern signal is to be recorded or formed is the duration of at least a defined portion of a cardiac cycle or a whole cardiac cycle or an integral number of a few cardiac cycles.

8. The electrotherapy device as set forth in claim 2 , wherein the electrotherapy device is designed in such a way that a respective period of time over which a respective impedance or conductivity pattern signal is to be recorded or formed is the duration of at least a defined portion of a cardiac cycle or a whole cardiac cycle or an integral number of a few cardiac cycles.

9. The electrotherapy device as set forth in claim 7 , wherein the impedance or conductivity measuring unit has an input amplifier with automatic input gain control (AGC) so that the respective gain of an output signal of an impedance or conductivity sensor of the impedance or conductivity measuring unit is as optimum as possible, wherein the impedance or conductivity measuring unit is adapted to scale an output signal of the input amplifier with a respectively associated gain factor.

10. The electrotherapy device as set forth in claim 1 , wherein the impedance or conductivity measuring unit has an input amplifier with automatic input gain control (AGC) so that the respective gain of an output signal of an impedance or conductivity sensor of the impedance or conductivity measuring unit is as optimum as possible, wherein the impedance or conductivity measuring unit is adapted to scale an output signal of the input amplifier with a respectively associated gain factor.

11. The electrotherapy device as set forth in claim 9 , wherein provided in the housing is a therapy device control unit which is connected to the evaluation unit and is adapted to set at least one therapy parameter such as univentricular or biventricular stimulation, interventricular delay time, atrio-ventricular delay time in dependence on a respective contractility signal or a contractility difference signal.

12. The electrotherapy device as set forth in claim 1 , wherein provided in the housing is a therapy device control unit which is connected to the evaluation unit and is adapted to set at least one therapy parameter such as univentricular or biventricular stimulation, interventricular delay time, atrio-ventricular delay time in dependence on a respective contractility signal or a contractility difference signal.

13. The electrotherapy device as set forth in claim 11 , wherein the therapy device control unit is adapted to set the respective therapy parameter in such a way that the contractility signal or the contractility difference signal exhibits maximum contractility.

14. The electrotherapy device as set forth in claim 13 , wherein provided in the housing is a data memory for the contractility signal and preferably additionally for the activity level signal.

15. The electrotherapy device as set forth in claim 1 , wherein provided in the housing is a data memory for the contractility signal and preferably additionally for the activity level signal.

16. The electrotherapy device as set forth in claim 11 , wherein the data memory has a plurality of memory regions for a reference signal pattern and for at least one prevailing impedance or conductivity signal pattern as well as for a respectively associated activity level signal pattern.

17. The electrotherapy device as set forth in claim 16 , wherein the data memory is connected to the therapy control unit.

18. The electrotherapy device as set forth in claim 11 , wherein the data memory is connected to the therapy control unit.

19. The electrotherapy device as set forth in claim 17 , wherein the data memory is connected to the evaluation unit.

20. The electrotherapy device as set forth in claim 11 , wherein the data memory is connected to the evaluation unit.

21. The electrotherapy device as set forth in claim 19 , wherein arranged in the housing is a data telemetry unit which is connected to the therapy control unit or the data memory or both.

22. The electrotherapy device as set forth in claim 11 , wherein arranged in the housing is a data telemetry unit which is connected to the therapy control unit or the data memory or both.