HK1182346A - Medical implant and medical arrangement - Google Patents

Description

Medical implant and medical device

Technical Field

The present invention relates to a medical implant and a medical device comprising the medical implant. In addition to implantable electrode leads (hereinafter also referred to as "electrode leads") or sensor leads, for example of the type used in cardiac pacemakers or implantable cardioverters, the term "implant" also relates within the scope of the present patent application, for example, to so-called "leadless pacemakers" (leadless cardiac pacemakers) of the type described in EP 1714670B 1, or for example to "leadless sensors", which are sensors that comprise a transmitter/receiver unit and that are implantable in the vasculature of a living organism or subcutaneously.

Background

It is very difficult for the doctor to remove the adhered electrode lead. Previously, for removal, the electrode leads have been "cut" using, for example, laser cutting or a conventional knife. Meanwhile, tension must be applied to the electrode lead, although the tension must not cause the lead to tear. Special systems have been developed for this difficult purpose, such as the electrode extraction system from the company VascoMed GmbH.

Various coatings (e.g., polymer-based coatings) have been known for a long time, many of which are intended to prevent adhesion of an electrode lead or other medical implant within the body, or many of which are active agent releasing coatings (drug eluting coatings) intended to prevent adhesion by releasing an active agent.

For example, the coating of the implant is obtained by embedding a hydrophilic interface between the surface of the implant and the body fluids. As a result, inflammatory response and adhesion of surrounding tissues are minimized. Currently, a variety of natural, synthetic and semi-synthetic materials are applied to implant coatings. Naturally occurring materials include alginates, chitosan, collagen, dextran, and hyaluronic acid, and synthetic polymeric materials such as polylactic acid (lactic acid) and poly (lactic-co-glycolic acid) (PLGA), 2-hydroxyethyl methacrylate, polyethylene glycol (PEG), and polyvinyl alcohol (PVA) as coating materials. Not all materials have the desired properties for a long time. Many materials do not provide sufficient mechanical load rates, chemical stability, or biocompatibility for all applications, and thus do not completely prevent adhesion.

Foreign body reactions to the implant can be minimized or even controlled by the use of steroidal and non-steroidal anti-inflammatory drugs. For example, glucocorticoids have been used.

For a long time, most electrode leads adhere to where they lie against the vessel wall and are therefore not removable or are almost very difficult to remove. Many of the above-mentioned materials are suitable only for a limited period of time, and do not permanently prevent foreign body reactions, and therefore do not permanently prevent adhesion of the implant, in particular of the electrode lead, the sensor (sensor connected to the lead, or leadless sensor), or the leadless pacemaker. To date, no coating (either neat polymer or drug eluting polymer) is known to solve the problem over a period of more than several months.

Even when using specially developed systems and the surgeons performing the surgery are very experienced, especially if the electrode lead has adhered, the dislodgement of the electrode lead in the vicinity of the heart is especially associated with a high risk that important blood vessels or the heart will be damaged. For this reason, when the electrode leads should be replaced, they are often left in the body.

Although it is difficult to assess the risks associated with electrode leads remaining in the body, electrode leads are now tolerated in order to avoid the occurrence of extremely high risks associated with dislodgement.

The problem addressed by the present invention is to provide a medical implant which is more suitable in terms of possible removals.

Disclosure of Invention

The problem is solved by an implant having the features of claim 1. Advantageous developments of the inventive idea lie in the subject matter of the appended dependent claims. Furthermore, a medical device having the features of claim 14 is provided.

The invention is based on the premise that, in order to remove a medical implant from an environment of tissue to which it has adhered, the previously generally applied high tensions for removing the medical implant are avoided according to the initially specified definition. Alternatively, the invention is further based on the premise that: to release the implant from the tissue environment, the implant is vibrated (e.g., more or less "rocked"). Finally, the invention comprises the following idea: the mechanical vibrations are not generated outside the body and are not transmitted to the implant by means of a mechanical transmission element, but are generated directly in the implant by means of a suitable energy transforming device. For this purpose, a transducer element is provided in the implant, which transducer element, when electrically and/or magnetically controlled, induces a mechanical vibration of the implant, resulting in a release of the implant from the tissue environment or at least a loosening of the implant in the tissue environment. It should be noted that this release or loosening does not necessarily have to take place solely for the purpose of removal and at the time of removal, but can also be carried out for preventive purposes, for example, in order to prevent a fixed adhesion at longer time intervals during the long service life of the implant.

The transducer elements in the ends of the electrode leads or sensor leads or in leadless pacemakers/sensors or similar implants will greatly simplify the development of future implant coatings, since the necessity of keeping endogenous cells away from the agglutinates is thereby reduced. Low levels of adhesion can be tolerated because even if there is adhesion in human tissue, dislodgement is possible with the present invention.

In addition, drug eluting coatings that may be harmful to the body are avoided. It is possible to control the point in time at which the tissue should release the implant at the time of removal.

Further advantages are provided because the endogenous adhesions additionally stabilize the position of the implant. This is particularly important for lead-connected or leadless sensors located in the pulmonary artery or vena cava in front of the heart. If the sensors slip, serious complications may result.

In one embodiment of the invention, the implant comprises a transducer element that inductively couples an alternating magnetic field. However, in a preferred embodiment from the present point of view, the transducer element is an electrically controllable transducer element, such as a piezo-ceramic vibrating element.

In another embodiment, the transducer elements are in the form of individual transducer elements inserted into the implant. In a further embodiment, the transducer elements are arranged in the wall area, in particular embedded in the wall over a large surface area. If the latter embodiment is combined with an embodiment as an electrically controllable piezoelectric element, an advantageous embodiment results in which the transducer element comprises a piezoelectric ceramic foil or a piezoelectric polymer foil.

The above mentioned piezoelectric foils are only a few micrometers thick and do not substantially increase the diameter of the implant. The piezoelectric foil is for example made tubular, which results in many production advantages. If possible, provision should also be made for the piezoelectric foil to extend along the entire longitudinal axis of the implant, since it is not possible to accurately determine the position at which the implant will adhere to the tissue.

In another embodiment of the invention, the proposed implant comprises an electrical connection for contacting the transducer element through a temporary control line as an explantation mechanism. In a further embodiment, the integrated control circuit is provided for connection to an internal control device, a control device arranged in another implant, or an extracorporeal control device.

In a further embodiment, the transducer elements are designed or an additional energy supply mechanism is provided such that wireless control is possible by means of an alternating magnetic field generated outside the body (for example generated by an excitation coil held at the body in the vicinity of the implant). The advantage of wireless energy supply of the transducer elements is that no additional technology will be needed in the main implant and no additional electrode leads will be needed.

In one application of the invention, which is particularly important from the present point of view, the implant is designed as an implantable electrode lead or sensor lead. In another embodiment, which is more interesting in terms of perspective view, the implant is a leadless cardiac stimulation device or cardioversion device, or a sensor connected to a lead or leadless sensor for in vivo, physical, physiological or biochemical measurements, the implant being known per se and having a cylindrical basic shape. In both application forms, a piezoceramic foil or a piezoceramic foil (in particular in the form of a sleeve or in the form of an annular segment) can advantageously be arranged in or on the wall of the distal section.

Furthermore, the proposed medical device comprising an implant of the above-mentioned type further comprises: a control device for electrically and/or magnetically controlling the transducer element; and coupling means for coupling energy in the transducer elements. The medical device may be a wholly implantable device (e.g., including pacemaker electrode leads and specially equipped cardiac pacemakers). However, from the present point of view, apparatuses in which the control device is in the form of an extracorporeal removal support device are of greater clinical interest.

Drawings

Advantages and useful features of the invention will also become apparent from the following basic description of embodiments with reference to the attached drawings. In the drawings:

fig. 1A shows a schematic view of a first embodiment of an implant according to the present invention using an example of a length of an electrode body of an electrode lead;

FIG. 1B shows a schematic view of another embodiment of an implant according to the present invention using an example of an electrode lead;

FIG. 2 shows a schematic view of another embodiment of an implant according to the present invention using an example of an electrode lead;

FIG. 3 shows a schematic view of another embodiment of an implant according to the present invention using an example of an electrode lead;

FIG. 4 shows a schematic view of another embodiment of an implant according to the present invention using an example of a leadless pacemaker;

fig. 5 shows a schematic depiction of a first embodiment of a medical device according to the present invention; and

fig. 6 shows a schematic depiction of another embodiment of the proposed medical device.

Detailed Description

Fig. 1A and 1B only schematically show parts of the distal end of an essential electrode lead 100 in connection with the present invention, which electrode lead in itself also comprises, in a known manner, one or more electrodes for stimulating body tissue susceptible to stimulation and/or for sensing tissue potentials, and optionally sensors for detecting other physiological variables in the patient. Those components of the electrode lead 100 and the supply and termination leads are not depicted nor further described herein because they are well known to those skilled in the art. Furthermore, features described with particular reference to electrode leads may also be applied to other devices to which the term "implant" relates.

Fig. 1A shows a longitudinal cross section of an electrode body section of an electrode lead 100. A piezoceramic foil 102, which in the embodiment shown here comprises an elongate sleeve, is embedded in the plastic sheath 101 of the electrode lead 100. A piezoceramic foil extends across at least a section of the electrode body, the piezoceramic foil extending between a proximal end in the direction of the implanted electromagnetic device and a distal end directed towards the treatment site. Also, a supply lead 107 for electrically connecting the therapy electrode or sensor electrode on the distal end of the electrode lead extends in the electrode body. The piezoceramic foil 102 is connected inside the electrode body to an electrical supply lead 104 by means of connection contacts 103 on the inner and outer surfaces of the piezoceramic foil, the electrical supply lead 104 in turn being connected to an electromagnetic device that has also been implanted, or to an external device, in particular in the case of dislodgement. As depicted in the embodiments described below according to fig. 1B, the piezoceramic foils can also be externally accessible to supply leads 106 provided in the individual cables 105 through the individual cables 105, to which the individual cables 105 are guided for removal.

If an alternating voltage of appropriate frequency and voltage is applied to the piezoelectric foil (piezo foil) 102, the piezoelectric foil will emit an acoustic wave. The emitted acoustic waves cause the adherent to detach or loosen from the electrode surface. The frequency of the applied alternating voltage may be in the range of 20kHz to 20MHz, and preferably a frequency between 50kHz and 100kHz is used. The ac voltage may be applied as a continuous ac voltage having any curved shape, or applied in bursts or pulses.

In a variant of the depicted embodiment, the transducer element can be designed with ring segments electrically connected to each other and can be made of a piezoelectric material, such as lead zirconate titanate (PZT), barium titanate or lithium niobate. The flexibility of the electrode in this region is increased by the ring segments. As an alternative to piezoelectric ceramic foils, foils made of piezoelectric polymers, such as polyvinylidene fluoride (PVDF), may also be used.

Fig. 1B illustrates another embodiment of the electrode lead 100. Depicted is the distal end of the electrode lead 100. A piezoceramic foil 102 is embedded in the plastic sheath 101 of the electrode lead 100, said piezoceramic foil 102 comprising, in the embodiment shown here, an elongated sleeve 102a and a hemispherical cap 102b in the distal electrode tip region (which is likewise hemispherical). By means of the connection contacts 103 on the inner and outer surface of the piezoceramic foil, the piezoceramic foil 102 is either (by means of the dashed lines in the present example) connected inside the electrode body to an electrical supply lead 105, which electrical supply lead 105 is in turn electrically connected to the likewise implanted electromagnetic device, or, in particular in the example of removal, the electrical supply lead 105 is connected to an external device by means of an electrode plug which is present on the proximal end of the electrode lead 100 and which is not depicted, or the piezoceramic foil 102 is externally contacted by means of a separate cable 105 which is guided to the piezoceramic foil 102 for removal to a supply lead 106 provided in the separate cable 105. To better illustrate the principle, the cable 105 is schematically guided distally to the piezoceramic foil. Of course, it will be appreciated by those skilled in the art that in the case of removal, such a cable is introduced into the interior of the electrode body from the proximal direction.

As a sketch of a variation of the embodiment depicted in fig. 1B, fig. 2 shows a distal end of an electrode lead 200 comprising a tip electrode 201 and a ring electrode 202, on which distal end a fixation coil 203 is arranged for fixation in body tissue to be stimulated, such as in the carpus pillar of the heart. A piezoelectric ceramic vibration body 204 in the form of a hollow cylinder, the inner wall and the outer wall of which body 204 are connected to the end of the receiving coil 205, is mounted in the electrode lead 200 near the distal end as a transducer element.

By means of such a coil 205, the energy for generating the sound waves is wirelessly supplied using magnetic inductive coupling. Upon removal, this is implemented by a suitable transmission coil (not depicted) which remains outside the body. This solution has the advantage that: the electrodes do not require any additional connectors and no additional special means for generating and supplying an alternating voltage are required in the Integrated Magnetodiode (IMD). Thus, such electrodes are fully compatible with conventional electrode connectors and integrated magnetodiodes.

As another example, fig. 3 shows an electrode lead 300, the electrode lead 300 comprising a tip electrode 301 as the only electrode, and the ends of the electrode lead 300 (represented by the distal dashed expansions) being elastically compressible so as to prevent penetration of the body wall if body wall contact occurs. The capacitive pressure sensor 302 is disposed proximate the distal end (e.g., with a compressible conductive foam) to determine the compressive force if contact of the electrode tip with the body wall occurs. The capacitive pressure sensor 302 is connected to proximal connection contacts (not depicted) of the electrode leads by electrode leads 303a and supply leads 303b connected to distal and proximal faces of the capacitive pressure sensor 302.

Thus, other possibilities of generating the desired sound waves are utilized. Capacitive pressure sensors can be used to generate sound waves by applying an alternating voltage to a pressure measurement capacitor. Then, the capacitive pressure sensor (conversely) is used as a capacitive micromachined ultrasonic sensor (CMUT). The means for generating an alternating voltage may for example be comprised in a means for determining a pressure signal from the capacitance of a capacitive pressure sensor. Alternatively, such an alternating voltage may also be wirelessly inductively coupled by suitable coils.

As another embodiment of the invention, fig. 4 shows a leadless pacemaker 400, the basic shape of the leadless pacemaker 400 being cylindrical and one end of the leadless pacemaker 400 terminating in a rounded tip 400a, at which tip 400a stimulation electrode 401 is arranged. A plastic fin 402 is provided near this end of the pacemaker 400 for fixation in branched body tissue at the site of application of the pacemaker. In addition to the usual components of such a device, the pacemaker 400 comprises a ring of oscillating bodies 403, which oscillating bodies 403 can be inductively excited by an external alternating magnetic field MF to cause vibrations, and which oscillating bodies 403 are placed near the attachment points of the fins 402. The oscillating body 403 in particular excites the fin 402 to undergo elastic oscillations which loosen the fixation of the fin 402 in the branched body tissue, thereby creating a prerequisite for dislodging the pacemaker 400 using a dislodging mechanism 410 (the dislodging mechanism 410 is here depicted symbolically only as a guide wire with a terminal external thread). As mentioned with reference to fig. 1 and 2, the removal mechanism 410 according to this embodiment may also serve as another embodiment of a contact that may contact the oscillating body 403 described above. In this example, the electrical energy is obtained by galvanic contact between the displacing mechanism (in particular by electrically induced contacts at the surface of the displacing mechanism) and the oscillating body. Contact surfaces inside the leadless pacemaker 400 ensure such contact. Of course, this type of energy coupling is also possible for other components included in the term "implant" as defined herein.

As a first example of a medical device according to the present invention, fig. 5 schematically shows an electrode lead 500, said electrode lead 500 comprising a piezoelectric foil 501 embedded near its distal end and two electrical supply leads 502a, 502b thereof, whereby said electrode lead 500 is connected to a cardiac pacemaker 510 such that the leads 502a, 502b are connected to an explanted transducer generator 511 in the pacemaker. The removal transducer generator 511 is activated in preparation for removal of the electrode lead 500, and the transducer generator 511 is energized by the pacemaker battery 512 for a predetermined period of time to cause vibration to loosen the lead end from the surrounding cardiac tissue.

As an alternative embodiment, FIG. 6 shows the distal end of an electrode lead 600 placed in the heart H of a patient P, which is mounted to an inductively driven oscillating body using a piezoceramic connected to a receive coil in the manner of the embodiment shown in FIG. 2, or also in the manner of a "leadless pacemaker" as shown in FIG. 4. In preparation for removal of such an electrode lead, an energy delivery head 610 is guided from the outside to the applicable body area, said energy delivery head 610 comprising a transmission coil 611 and being connected to an external supply and control device 612. Energy is supplied from the energy supply head 610 to transducer elements (not separately shown) in the electrode lead 600 in the manner described above using an electromagnetic alternating field. Thus, the generator contained in the supply and control device 612 provides an alternating voltage for a suitable time, which is sufficient to loosen the electrode leads and not harmful to the health of the patient.

The embodiments of the invention are not limited to the examples and aspects highlighted above, but are also possible in a large number of modifications within the processing scope of the person skilled in the art.

It will be apparent to those skilled in the art that many modifications and variations to the examples and embodiments described are possible in light of the above teachings. The disclosed examples and embodiments are presented for purposes of illustration only. Other alternative embodiments may include some or all of the features disclosed herein. Therefore, the invention is intended to cover all such modifications and alternative embodiments as may fall within the true scope of the invention.

Claims (16)

1. A medical implant comprising a transducer element which, when electrically and/or magnetically controlled, induces mechanical vibration of the implant.

2. The implant of claim 1, comprising a transducer element that inductively couples an alternating magnetic field.

3. The implant of claim 1, comprising an electrically controllable transducer element.

4. The implant of claim 1, wherein the transducer element is in the form of an oscillating body detachably inserted into the implant.

5. Implant according to claim 1, wherein the transducer elements are arranged in a wall region of the implant, in particular embedded in the wall over a large surface area.

6. The implant of claim 3, wherein the transducer element comprises a piezoelectric ceramic foil or a piezoelectric polymer foil.

7. The implant of claim 1, comprising electrical connections for contacting the transducer element using temporary control lines as an explantation aid.

8. The implant of claim 1, comprising: an integrated control circuit, which is connected to the internal control device, to a control device arranged in another implant or to an extracorporeal control device.

9. The implant according to claim 1, wherein the transducer element is designed for wireless control by means of an electromagnetic alternating field generated outside the body, or a further energy supply mechanism is provided for wireless control by means of an electromagnetic alternating field generated outside the body.

10. The implant of claim 9, wherein the implant comprises a receive coil arrangement inserted into or connected to the transducer elements.

11. The implant of claim 1 in the form of an implantable electrode lead or sensor lead.

12. The implant according to claim 11, wherein a piezoceramic or piezoceramic foil is arranged in or on a wall of the distal section, in particular a piezoceramic or piezoceramic foil in the form of a sleeve or an annular section is arranged in or on a wall of the distal section.

13. The implant of claim 1, in the form of a leadless cardiac stimulator or cardioversion device, or as a leadless sensor.

14. The implant according to claim 13, wherein a piezoceramic or piezoceramic foil is arranged in or on a wall of the distal section, in particular a piezoceramic or piezoceramic foil in the form of a sleeve or an annular section is arranged in or on a wall of the distal section.

15. A medical device, the medical device comprising: the implant of claim 1; a control device for electrically and/or magnetically controlling the transducer element; and a coupling mechanism for coupling energy in the transducer elements.

16. The apparatus of claim 14, wherein the control device is in the form of an extracorporeal removal support device.