Abstract:
The disclosure relates to an artificial heart implant comprising a blood pump with a pump drive, a controller for controlling and regulating the pump drive, and an electrode that is connected to the controller and is used for detecting electrical quantities on the patient&#39;s heart. The controller controls the pump drive in accordance with the signals detected by the electrode.

Description:
BACKGROUND 
     1. Field of the Disclosure The disclosure refers to an artificial heart comprising a blood pump with a pump drive and a control for controlling and regulating the pump drive. 
     2. Discussion of the Background Art 
     In the present context, an artificial heart is to comprise all intra- and extracorporeal artificial hearts that are provided with a blood pump, i.e. extracorporeal, fully or partly implantable artificial hearts, cardiac assist systems and the like. Known artificial heart implants operate at a fixed pumping frequency or include a simple sensor system that detects and controls or regulates the motor current or the filling of the pumping chamber. Extracorporeal artificial hearts derive ECG signals exteriorly from the skin of a patient, which signals are rather weak and inaccurate due to the distance from the heart. Intracorporeal artificial hearts derive the necessary delivery rates from the motor current, the blood flow and similar parameters. These methods are limited in their accuracy and they are unreliable. 
     DE 697 31 848 T2 discloses a cardiac assist system controlled by means of ECG electrodes. 
     DE 693 22 562 T2 discloses a muscle stimulation arrangement wherein an electrode probe in the vicinity of a patient&#39;s heart is used to lead ECG signals. 
     It is an object of the disclosure to provide an artificial heart that is simple to implant and permanently provides good electrode signals. 
     SUMMARY 
     According to the disclosure, an electric sensor connected with the control is provided to detect electric values immediately at a patient&#39;s heart. The control controls the pump drive in dependence on the signals detected by the sensor. 
     The sensor may be formed by one or a plurality of ECG electrodes and/or one or a plurality of impedance electrodes. Thus, important physiologic parameters are detected that indirectly yield information about the physiologically required blood volume flow. This information is obtained, in particular, via the ECG electrodes placed or adapted to be placed immediately at a patient&#39;s heart, which detect myocardially evoked signals with high accuracy in detail. In this context, it is assumed that the cardially evoked signals are still present and accurately represent the physiological need of blood. 
     Because of the immediate proximity of the deriving point to the patient&#39;s heart, an ECG signal is obtained that is very detailed and allows for a precise control and regulation of the artificial heart. Besides a precise control of the blood pump or the pump drive, using the information obtained through the sensor or sensors also allows for a permanent monitoring of the patient&#39;s circulation or the patient&#39;s heart. 
     A blood line of the artificial heart implant is provided with one or a plurality of electrodes. The hose-like blood line has one or a plurality on its outside. The electrodes are rather large and are arranged as rings, for example, on the outer side of the blood line. 
     The signal lines connecting the electrodes with the control are located in or at the sheath of the blood line. Thus, the signal lines are quite well protected against excessive movements, bending or kinking. 
     According to a preferred embodiment, the signal line or the signal lines is/are helically provided in or at the blood line sheath. Thereby the minimum bending radii of the signal lines are very large so that the risk of line ruptures is low even in the long term. 
     Preferably, an electric module is provided between the electrode and a control computer, at least one short-circuit line bypassing the electric module and being directly connected with the control computer. The electric module may be an amplifier and/or a filter and/or an A/D converter. When the module or the series-connected modules are operated appropriately, the electrode signal successively passes all electrode modules in order to then be supplied to the control computer in an amplified, filtered and digitalized state. Via the short-circuit line or the short-circuit lines, the same electrode signal can be supplied directly to the control computer, bypassing one, a plurality or all of the electric modules. The control computer can continuously compare the signal on the short-circuit line with a signal coming from the last electric module. Thereby, a redundancy is achieved that guarantees the operational safety that is essential to a vital implant such as an artificial heart. 
     The following is a detailed description of several embodiments of the disclosure with reference to the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the Figures: 
         FIG. 1  is a schematic illustration of a patient&#39;s heart provided with an intracorporeal artificial heart implant, 
         FIG. 2  is a schematic illustration of several modules of the artificial heart control of the artificial heart implant in  FIG. 1 , 
         FIG. 3  is an alternative embodiment of an arrangement of electrodes at a probe for detecting electric values at a patient&#39;s heart, and 
         FIG. 4  illustrates another embodiment of electrodes for detecting electrical values at a patient&#39;s heart. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  illustrates a patient&#39;s heart  10  supported by an artificial heart implant  12 . The artificial heart implant  12  is a so-called full implant, i.e., it has no direct physical connection to the extracorporeal. 
     The artificial heart implant  12  has an inlet line  14  whose inlet side is sutured to the left ventricle of the patient&#39;s heart  10 , a pump unit  16  into which the inlet line  14  opens, an outlet line  18  into which blood is pumped by the pump unit  16  and which opens into the aorta of the patient&#39;s heart  10 , and an intracorporeal energy supply  20  electrically connected with the pump unit  16  through signal and data lines. The inlet and outlet lines  14 ,  18  are blood lines. 
     Further, electrodes  26 ,  27 ,  28  are arranged at the pump unit  16  and connected with the pump unit  16  via corresponding signal lines  24 , which electrodes are ECG electrodes serving to lead myocardially evoked signals. 
     The pump unit  16  comprises a mechanical blood pump  30  supporting the patient&#39;s heart  10 , the blood pump being driven by an electric pump drive  32 . Further, the pump unit  16  comprises a control  34  connected, via signal and data lines, with the pump drive  32 , the electrodes  26 ,  27 ,  28  as well as the energy supply  20 . The control  34  controls the pump drive  32  in dependence on, among others, the ECG signal detected by the electrodes  26 ,  27 ,  28 , for example, synchronous with the ECG signal. The ECG electrodes  26 ,  27  provided at the patient&#39;s heart  10  are sutured to the patient&#39;s heart  10 . 
     At the open, heart-side end of the inlet line  14 , further electrodes  29 ,  31  are provided that are illustrated in  FIG. 4 . The ring electrodes  29 ,  31  are made of metal or an electrically conductive plastic material. The ring electrodes  29 ,  31  are connected with the control  34  by helical signal lines  38  placed on the hose-shaped wall of the inlet line  14 . 
     The signal line may also be incorporated in the inlet line wall as a wire or a fabric. The signal line is insulated and is thus accommodated in the inlet line wall in a kinking- and rupture-proof manner. If a smooth basic material is used for the inlet line, e.g. silicone or PUR, the signal line may be molded into the inlet line wall. If the inlet line has a larger dimension or has a sheath, it can support and stabilize the inlet line wall and can thus protect the inlet line wall from collapsing. Instead of a helically placed signal line  38 , the same may alternatively be placed axially or almost axially within the inlet line. 
     To ensure a good ingrowth of the distal inlet line end with the cardiac tissue, an end portion of the inlet line  14  has a velour covering  33  on the outside. 
     The separate ECG electrodes  27 ,  28  illustrated in  FIG. 1  are configured as so-called fractal electrodes, i.e. they have a self-similar fractal structure, e.g. Romanesco, at their end. A high signal quality is achieved thereby. The lengths of the electrode lines  24  are fixedly predetermined. It is not possible to shorten the lines  24  during the operation. The control-side ends of the signal lines  24 ,  38  are provided with contact faces that are fixed in a corresponding terminal using a terminal screw and are thus connected at and with the control  34 . 
     Depending on the desired signal type, i.e. ECG signal or impedance signal, the electrodes  27 ,  28  are positioned on the left ventricle in an optimum position with respect to the potential line so as to obtain an optimally evaluatable ECG signal. If it is intended to obtain an atrium ECG for determining atrial fibrillation, an electrode should also be positioned there. 
     For a measuring of impedance-cardiographic characteristics of the patient&#39;s heart  10 , three to four electrodes must be provided, namely one or two ground electrodes  26 , a signal electrode generating a signal of 150 kHz, for example, and an impedance electrode. A single ground electrode is sufficient, if a large-surface housing is used as the ground electrode. 
       FIG. 3  illustrates an electrode probe  40  useful as an alternative or a complementary means to the arrangement in  FIG. 1 , whose distal end has three electrodes  42 ,  44 ,  46  provided thereon. The end electrode  42  has a hook  43  which is inserted into the myocardium to which it may be sutured, for example. The two other electrodes  44 ,  46  are annular in shape. The maximum value of potential is defined by the mutual distance of the three electrodes  42 ,  44 ,  46 . One of the electrodes  46  may form the ground electrode, fro example, while another electrode  44 ,  42  may form an ECG electrode. 
     Using corresponding insulated lines, the three electrodes  42 ,  44 ,  46  are placed in a probe sheath  48  in a kinking-proof manner. Thus, ruptures in the signal lines are avoided in the long term. 
       FIG. 2  illustrates several electronic modules  61 ,  62 ,  63 ,  64  of the control  34 , namely an amplifier module  61 , a filter module  62 , an A/D-converter module  63  and a control computer  64 . Further, two short-circuit lines  66 ,  68  are provided that directly connect the signal line  67 ,  69  between the amplifier module  61  and the filter module  62  or between the filter module  62  and the A/D converter module  63  with the control computer  64 . The control computer-side inputs for the two short-circuit lines  66 ,  68  are configured as A/D converters. 
     The analogue signals from the electrodes are supplied to the input of the amplifier module  61  via the signal lines  24 . From there, the amplified signal is transmitted to the filter module  62  via the signal line  67 . The electrode signal filtered by the filter module  62  is supplied to the high-resolution A/D converter module via the signal line  69 . From there, the digitalized electrode signal is transmitted to a digital input of the control computer  64 . 
     The connection of the A/D converter module(s)  63  with the control computer  64  may be established through an I 2 C- or a SPI-bus. 
     By means of the short-circuit lines  66 ,  68 , the control computer  64  may check the processed electrode signal received by the A/D converter module  63  for extensive consistence. Further, in the event of a failure of the filter module  62  and/or the A/D converter module  63 , sensor signal from the amplifier module  61  can still be used and be further evaluated, albeit in lesser quality. 
     Thus, a high degree of controllability and redundancy is realized using simple means. Furthermore, modules  62 ,  63  can thus be calibrated posteriorly. 
     The control  34  controls the performance of the pump drive  32  as a function of the ECG and impedance signals measured by the electrodes, e.g. in a manner synchronous with the heart beat. 
     The electrodes  26 ,  27 ,  28 ,  29 ,  31  that are in contact with the bloodstream may be provided with coagulation-inhibiting coatings or they may have special surfaces allowing no or only little accretion of blood plates. This also applies to the electrodes that may come into contact with blood in certain areas outside the bloodstream, in which the accretion of thrombocytes may be dangerous.