Implantable device

The invention relates to a permanently or temporarily implantable device comprising an elongate electrical conductor.

Such devices, for example, electrode lines for electrostimulation, have the disadvantage that their electrical conductor can heat in an MRI scanner, because the ruling in MRI scanners alternating magnetic fields in the electric conductor induce not inconsiderable electric currents. Even those induced currents can be delivered via the electrode poles of the electrode lead to the surrounding tissue and so, for example, lead to undesired tissue heating. Therefore, pacemaker patients can not or only partially be examined in an MRI scanner these days usually.

An implantable cardiac pacemakers or defibrillators (hereinafter also referred to as cardiac stimulators or IPG (implantable pulse generator) refers) are in fact typically at least one stimulation electrode lead connected, which has a standardized electrical connection at its proximal, provided for connection to the pacemaker or defibrillator end and having its distal, for placement in the heart foreseen end one or more electrode poles. Such an electrode pole serves for delivering electrical pulses to the tissue (myocardium) of the heart or for sensing electrical fields, to sensing an activity of a heart in the so called oversensing can. For these purposes form electrode poles typically electrically conductive surface portions of an electrode line. Electrode poles are typically provided as an annular electrode in the form of a ring around the electrode line or in the form of a tip or tip electrode at the distal end of the electrode line. The electrode poles are through one or more electrical conductors connected to contacts of the electrical connection of the electrode line at the proximal end thereof electrically conductive. Thus extend between the contacts of the electrical connection, the electrode leads at the proximal end and the electrode poles at the distal end of the electrode line, one or more electrical conductors which connect one or more of the electrode poles with one or more of the contacts electrically. These electrical conductors may be used to the proximal end of the electrode line and also each referred to the description proceeds as a function of management on the one hand for the transmission of stimulation pulses to the electrode poles and the other part for transmission by means of the electrode poles recorded electrical signals. Such functional lines for the functions of each electrode line required electrical conductor and as such subjected to the risk that are induced in them by external alternating magnetic electric currents, which can for example lead to undesirable heating of the function lines or its associated electrode poles or to submit corresponding currents through the electrode poles to surrounding tissue and thus may lead to a heating of the surrounding tissue.

The invention has for its object to provide a device which solves the problem described above.

This object is achieved by a temporary or permanent implantable medical device, which is connected to at least two elongate electrical function conductors for the transmission of therapy signals or diagnostic signals, or both, or to join, and at least one associated with at least one of the functional lead electrode pole, electric on the power to leave to surrounding body tissue in the use case or the electrical potentials in surrounding the use case tissue can be sensed, or both.

According to the invention, the medical device is a wave transfer module that is connected to the function conductor or connect to and which is designed to transform incoming via a function manager waves so and intrude controlled as transformed wave to another function manager or the same function conductor such that the waves superimposed on the electrode pole destructive.

A medical device for which the invention is especially relevant is, an electrode line, for example for a heart stimulator, in which the functional conductors are electrical conductors of the electrode lead, the electrode lead comprising electrode poles which are electrically connected via the function conductor to the shaft transfer module.

The medical device, such as a connected to an electrode line of implantable cardiac stimulator may have a housing, which is electrically conductive or has an electrode terminal, can be delivered via the in use case electric current to surrounding body tissue or sensed with the electrical potentials in surrounding tissues or both.

Preferably, the medical implement has a Störfelderkennungsvorrichtung which is formed to detect a presence of strong electromagnetic fields and in the case of the presence to generate a corresponding output signal, and which is connected to a control unit for controlling the transfer shaft module.

The Störfelderkennungsvorrichtung may comprise a temperature sensor which is arranged so that it can detect a heating of an electrode. In this way the Störfelderkennungsvorrichtung detects a warming as a result of high-frequency interference and thus interference indirectly through its effect. The temperature sensors are located on the electrode poles or other locations that can become hot as a result of interactions with electromagnetic fields.

Alternatively or additionally, the Störfelderkennungsvorrichtung include a sensor for induced in a function conductor currents or voltages, and thus be adapted to detect induced currents or voltages directly.

According to a preferred embodiment, the wave transfer module a delay line delays the electromagnetic waves and or rejected, so that during operation a transformed wave is formed, which is superimposed on an induced wave on the same or another function conductor destructive and compensates for the induced wave in this way , The delay line can have an impedance that causes this effect.

According to one embodiment, the delay line is covered by one or more, preferably discrete electronic components is realized from a group comprising the coils, capacitors, resistors and resistive transformer (pulse transformer). This form for example, an LC circuit, and possibly also with an ohmic resistor in order to adjust the damping.

Additionally or alternatively, the delay line may have three-dimensional structures that have wellenverzögernde and / or damping action due to their physical properties. Such three-dimensional structures are not necessarily discrete electronic components but as a waveguide, a coaxial line, a strip line, possibly with lossy materials to adjust the damping. Here, the wave transfer module is preferably adjustable with respect to its activity, in particular in terms of its delay effect and / or its damping effect, for example, by the adjustable elements are operated electrically, mechanically, optically, etc. The adjustment of the controllable delay lines can also be done by an external programmer.

It makes sense, the wave transfer module, a switching unit which is arranged and designed, transformed waves on a value determined by the switching unit Function Head intrude or not. This allows to use only the wave transfer module when it is necessary and moreover adapt to the respective application. The switching unit can also be done by an external programmer.

According to a preferred embodiment, a delay line of the wave transfer module connects at least two function conductors, the connection is made via the switching unit. The switching unit may have the form of a switching matrix, wherein each cross point is occupied in the switch matrix by a switch.

According to another embodiment, the medical device may include a termination impedance unit and the wave transfer module having a switching unit which is arranged and designed to combine a functional lead with a termination impedance unit. The termination impedance can cause a phase shift of a wave on a functional lead and so also contribute to the desired effect of wave cancellation. For this purpose, preferably at least one impedance value of the load impedance unit electrically, mechanically or optically controllable. The termination impedances may be implemented discretely or physically. The adjustment of the controllable termination impedances can also be done by an external programmer.

The control unit is preferably configured to control the controllable delay lines and / or the controllable termination impedances and / or the switching unit in response to an output signal of Störfelderkennungeinrichtung so that in case of application-induced interference heating is minimized to the electrode poles.

Particularly preferably is a battery powered electronic implant with an electrically conductive housing or a housing with at least one electrode pole, electrical functional conductors connecting the electrode poles electrical feedthroughs of the implant, to conduct electrical signals from the respective electrode to the implant can, a Störfelderkennungsvorrichtung for detecting the presence of strong electro-magnetic fields in particular MRI fields, and a wave transfer module that is controlled by the Störfelderkennungsvorrichtung via a control device and the at least one functional lead to implant incoming waves so transformed and aufschaltet at least one other functional lead that the waves at the distal electrode poles destructive overlap, so that there the MRI-related heating is minimized.

As an alternative to a controllable termination impedance can also be a controllable generator can be provided which is designed to actively feed a compensation signal in a functional lead. The to be fed compensation signal has the same frequency as that of the interference signal and a certain phase position of the frequency is determined by the Störfelderkennungseinheit and the phase position and amplitude by evaluation of the temperature signals are adjusted so that the interference field induced heating of the electrode poles (optionally allg. The temperature measurement points, ) is minimized.

The invention will now be explained by means of embodiments with reference to the figures. The figures show the following:<dl id="dl0001"><dt>Fig. 1</dt><dd>shows, as implantable medical devices an implantable heart stimulator 10 and an attached implantable electrode lead 20th</dd><dt>FIG. 2</dt><dd>shows in a highly schematic representation of the internal structure of a heart simulator invention.</dd><dt>Fig. 3</dt><dd>shows in a highly schematic representation of a structure of a delay line.</dd></dl>

The implantable cardiac stimulator 10 may be a pacemaker or a cardioverter / defibrillator (ICD). In the illustrated embodiment of the heart stimulator 10 is a ventricular pacemaker and defibrillator. Other known heart stimulators are dual chamber pacemakers for stimulating the right atrium and the right ventricle or biventricular pacemakers, which also can stimulate the left ventricle in addition to the right ventricle.

Such stimulators typically have a housing 12, which is usually made of metal and thus is electrically conductive and can serve as a large-area electrode pole. On the outside of the housing 12, typically a terminal housing 14 is fixed, which is also referred to as a header. Such a header typically has contact sockets for receiving plug contacts. The contact sockets have electrical contacts 16, which are connected by respective conductors with a disposed in the housing 12 of the heart stimulator electronics 10.

The electrode line 20 is in the context of this invention also an implantable medical device. At the distal end of the electrode line 20 a tip or tip electrode 22 and, arranged in the vicinity of the ring electrode 24 are in a known per se manner electrode poles in the form provided. The electrode poles 22 and 24 are designed such that they are depending on the function of a cardiac stimulator, to which the electrode lead 20 is connected, for sensing electrical potentials of the cardiac tissue (myocardium) or for delivering electrical signals, for example for delivery of stimulation pulses to the surrounding them heart tissue, are formed.<figref idrefs="f0001">figure 1</figref> shows how the electrode poles, that is, the tip electrode 22 and ring electrode 24, in the application, the electrode line 20, located in the apex of a right ventricle of a heart.

Both the tip electrode 22 and ring electrode 24 are each at least one electrical conductor 26 is electrically connected to a plug contact 28 at the proximal end of the electrode lead 20th The plug contact 28 has electrical contacts which correspond to the electrical contacts 16 of the contact socket on the connector housing 14 of the implantable cardiac stimulator. The electrical conductors 26 in the electrode line 20 may be formed as approximately extended cable conductor or as helically coiled conductor. Such conductors functional electrode poles are electrically conductively connect with electrical contacts of the plug contact on the proximal end of the electrode lead 20 in this text referred to as functional lead, as they transmit, for example, the treatment serving electrical signals from plug contact the respective electrode or sensed electrical potentials signals representing the lead respective electrode to the plug-in contact and thus serve the elementary function of the medical device.

The electrical conductors 26, the electrode poles 22 and 24 respectively connect with the electrical contacts of the plug 28 of the electrode lead 20 are surrounded over most of its length by an insulating sheath, so that an electrical contact with the tissue of the heart selectively via the electrode poles comes about.

In addition to the electrode poles 22 and 24, typically of (in this case, ventricular) serve stimulation of cardiac tissue, the electrode line has 20 also two larger-area electrode poles 30 and 32 which serve as defibrillation electrodes and formed from at least one blank lying helically coiled wire are ,

It should be noted that the invention in the context of this embodiment will be explained with reference to a right ventricular pacemaker and defibrillator. As a medical device according to the invention can in principle but for example also serve a Ablationselektrodenleitung, which also extends the application to the heart of a patient and which is controlled by an element located outside the patient's device and is for this purpose connected to this.

<figref idrefs="f0002">figure 2</figref> shows a schematic representation of the internal structure of a medical device according to the invention. The medical device has an electrically conductive housing 100, the housing 12 from<figref idrefs="f0001">figure 1</figref> equivalent. Connected to the housing are two electrode lines 102 and 104, each having a tip electrode 106 and a ring electrode 108th Each of the tip electrode 106 and ring electrodes 108 forms a respective electrode pole. Each electrode pole is connected via a separate feed line 110 to an electronics inside the housing 100th The leads 110 each form a functional lead. In each case in the immediate vicinity of the electrode poles 106 and 108, temperature sensors 112 are arranged, which are connected via signal lines 114 to a control unit 116 inside the housing 100 si ND.

Instead of the temperature sensors 112, other sensors for sensing of electromagnetic interference fields or induced in the leads 110 may be currents or voltages.

The leads 110 (functional manager) and the signal lines 114 are in <figref idrefs="f0002">figure 2</figref> not plug and illustrated via housing openings 140 in the housing 100th The functional lead 110 stands in connection with the typical ingredients of a cardiac stimulator and sensing units or stimulation units. This is in<figref idrefs="f0002">figure 2</figref> lump sum represented by block 118, which represents the sensory and therapeutic pacemaker electronics.

In <figref idrefs="f0002">figure 2</figref> it is shown that the function of conductors 110 on the one hand lead to the pacemaker electronics 118 and also to the switching units 120 and 122, which are constructed as switching matrices. With the switch matrices 120 and 122, a wave transfer module 124 is connected, the (in the illustrated case three) adjustable delay lines comprises 126th The delay lines 126 are adjustable with respect to their delay effect and / or their damping effect. To this end, they are connected via control lines 128 to the control unit 116th In this way they can be received by the control unit 116 in dependence of the signals 116 receives the control unit via the signal lines 114 from the sensors 112 in the electrode leads 102 and 104th Concretely, the control unit 116 is adapted to receive both the switch matrices 120 and 122 and the delay lines 126 as a function of the received through the signal lines 114 signals so as to display the through the signal lines 114 incoming signals as possible no heating of the electrode poles 106 and 108th In this sense, the control unit 116 can be considered also as regulator.

The latter effect is achieved by using the adjustable delay lines 126 that the function manager 110 incoming waves are coupled to the adjustable delay lines 126 and the delay lines 126 are adjusted so that the waves transformed in a manner and to the same or another function conductor are connected such that they overlap destructively with induced waves and so cancel out the effect of the induced waves.

This purpose is alternatively or additionally a termination impedance unit 130, the adjustable in the concrete case three termination impedances 132 has. The adjustable impedances 132 can be set by the control unit 116 via control lines 134th By adjustable termination impedances 132, the reflection of the waves can be set to the function conductors 110 at the proximal, defined by the termination units ends regarding phasing and damping to achieve in this way also a destructive superposition of waves in the area of ​​the electrode poles of the respective functional lead.

Instead of the termination impedance unit 130 may also be a compensating signal generator can be provided which generates active and controlled by the control unit 116 compensation signals and feeds it to the appropriate functional manager.

It should be noted that the housing 100 of the cardiac stimulator represents a separate pole, which is (see reference numeral 136) with the switch matrices 120 and 122 and the Herzstimulatorelektronik 118 also connected electrically.

The control unit and thus the behavior of the switching units 120 and 122 as well as the settings of the delay lines 126 and the termination impedances 132 are externally programmable. This is indicated by the arrow 300th

The structure of an exemplary delay line in <figref idrefs="f0003">figure 3</figref> shown schematically. In<figref idrefs="f0003">figure 3</figref> numerals:<dl id="dl0002"><dt>200:</dt><dd>Conductive implant case</dd><dt>210:</dt><dd>Line an electrode</dd><dt>211:</dt><dd>Line of an electrode (the same electrode as 110 or another)</dd><dt>220:</dt><dd>Wave transfer module</dd><dt>230:</dt><dd>Head of the delay line</dd><dt>240:</dt><dd>Common of the delay line</dd><dt>250:</dt><dd>Connection of the reference conductor of the delay line to the implant housing</dd><dt>260, 261:</dt><dd>switch</dd><dt>270, 271:</dt><dd>Connection to the electronic</dd></dl>

Upon detection of a strong electromagnetic field (in particular HF fields as scanners occur in MR and which represent a potential danger for the patient and the implant) by the temperature sensors 112 and the control unit 116, which constitute in this sense a Störfelderkennungseinheit, is automatically the connection of the electrode inputs in implant reconfigured. This causes the control unit 116 that is programmed or constructed. This wiring is temporary while the fault is, in everyday operation of the implant is the high resolution and wideband signal recording, in particular, the impedance determination for a hemodynamic sensor, not affected. Then, the electrode leads directly (as conventionally) to run in the electronics 118 of the cardiac stimulator. In a preferred implementation is 118 to some or all inputs switched off during the fault and circuits according to the invention with delay lines the electronics. One purpose provided, controlled by the control unit 116 switch is in<figref idrefs="f0002">figure 2</figref> not shown.

In <figref idrefs="f0002">figure 2</figref> is an optional additional Störfelderkennungseinheit 150 is shown, which generally is responsive to interference fields and in this case, the control unit 116, as described above, is activated for the duration of the disturbing fields or a predetermined time period.

In a preferred implementation, the coupling of the supply lines by means of the switch matrices 120 and 122 is performed so that for example the inner conductor of a first electrode (coaxial) is switched to the outer conductor of a second electrode. In another implementation, at the same time, the inner conductor of the second electrode is connected to the outer conductor of the first electrode (cross-coupling). In another implementation, this is the delay quasi 0 seconds, that is directly connected without the use of delay lines.

In the interconnection of the electrodes is also ensured for the optimization with regard to the heating that the entrapped between the electrode surfaces are minimal. This induced MRI gradient stresses are minimized, reducing the risk of unwanted (induced by the MR scanner) cardiac stimulation. In particular, no connection is made to the housing potential.