Pacing lead with folding anchoring tines for an implantable medical device, especially for a heart pacemaker

0001The invention relates to a probe for an implanted medical device, particularly for pacemaker.

0002These probes, including endocardial pacemaker heart, include retention systems mounted on their end distal, close to the stimulation electrode itself said (or electrodes, in the case of a bipolar lead). various systems retention or anchoring have been proposed, including fasteners hook-shaped or "beards" that become jammed themselves between endocardial trabeculae.

0003The US Patent 4,236,529 describes such a probe, such as "passive fixation" that is to say, in which the barbs are housed themselves in place by elasticity, ensuring inclined shape check effect without any special operation.

0004It has also been proposed probes mechanical actuator, as for example in US-A-4,945,922, US-A-4957118 or EP-A-0 546 414 in which the barbs, initially folded against the body of the probe, are deployed by manipulating a coaxial mandrel inserted in the probe at the time of implantation and the rotation comes protrude barbs once the distal end of the probe positioned in the desired location.

0005The interest in recent fixtures is that they are generally reversible, so as to allow an explantation probe, for example after folding barbs by a reverse operation a mandrel inserted into the central axial channel of the probe. In However, these probes are both bulkier (the diameter of the body is more important because it is necessary to provide an axial channel) and structure more complex - hence more expensive - due to the need to provide a mechanical system for transmitting the movement of rotation of the mandrel and of converting the rotational movement into a deployment movement articulated beards.

0006One of the aims of the present invention is to provide a probe which can be implemented without actuator of the anchoring system. A Another object of the invention to provide such a probe that is extractable without risk of tearing of trabeculae or fibrous tissue which may have formed around the end of the probe.

0007The probe of the present invention thus combines the advantages of small diameter, simple structure and therefore inexpensive, easy implementation without using special instrumentation and possibility extraction without damaging the surrounding tissues. She allows, as will be explained below, using a probe body sealed and independent of barbs deployment system.

0008To this end, the probe according to the invention comprises, firstly, a body cylindrical bearing the electrode or electrodes of the probe and, hand, a removable sleeve styling the electrode body. the sleeve comprises a sleeve of the retaining ring on the body, the mounting this ring on the body being detachable to allow dissociation higher of the sleeve from the body by axial tensile the latter, and deformable means extending from the ring retention and may take two stable configurations. The passage from the first to the second configuration results from a solicitation outer axially on the sleeve and the deformable means essentially does not protrude radially in the first configuration, so as to allow the introduction in place of the probe, and being essentially radially into the second configuration so as to form anchoring barbs.

0009Preferably, the anchoring barbs of the deformable means are interconnected by a moving element surrounding the body and sliding along the latter between an initial position and a final position, these two positions corresponding respectively to both configurations stable deformable means, the deformable means connecting means between the retaining ring and the movable member.

0010In a first embodiment, the moving element is a skirt placed distally relative to the ring, this skirt being axially projecting from the body in the initial position and does not protrude in the final position, and the transition from the first to the second configuration resulting from external stress exerted axially in the proximally over the distal end of the skirt during docking of thereof with a wall against which is to contact the electrode.

0011Advantageously, it is then provided means for increasing the friction between body and skirt in the vicinity of the final position, including when the body presents an increased outside diameter and / or skirt presents an increased inside diameter, or when the body has reliefs on its outer surface and / or the skirt presents reliefs on its inner surface.

0012The body may have a rear stop shoulder of the final position, and it may further be provided on the end face of body an anchor screw, said screw being covered by the skirt initial position and projecting axially in the final position. This last configuration protects susceptible tissue trauma be caused by the anchoring screw during insertion of the probe to placement in a heart chamber.

0013In a second embodiment, the moving element is a ring placed proximal to the ring, and the passage from the first to the second configuration results from the external force exerted axially in the distal direction on the annulus by handling a threaded sleeve on the body. In this case, the holder body advantageously a blocking circumferential groove receiving and immobilizing the ring late in the race.

0014In all cases, the connection means preferably comprise a plurality of bridges in a mater iau elastically deformable, the bridges with section including a concave profile, the concavity being reversed between the first and second configuration.

0015Moreover, the retaining ring preferably has a substantially ring and the cylindrical body possesses a peripheral groove circular section receiving the O-ring, and throat torus having substantially identical diameters so as counterparts to allow at any point the local pivot the ring in the throat.

0016We will now describe examples of implementation of the invention.

0017Figure 1 is an exploded perspective view of the distal end a probe according to a first embodiment of the invention, showing the two essential elements of it, body and sleeve.

0018Figure 2 is a longitudinal section on a radial plane, the muff.

00193 illustrates the sleeve of the deformation of the kinematic the time of establishment of the probe upon contact with the heart wall, respectively for AA and BB sections of the 2.

0020Figures 4 to 6 show the successive stages of implementation of the probe.

0021FIG 7 is a perspective view showing the configuration of the probe according to the first embodiment of the invention, in its position final anchor.

00228 illustrates the manner in which probe can be removed from the body despite the formation of fibrous tissue around thereof.

00239 illustrates an advantageous variant of this probe, in which is provided a fixing screw.

0024Figure 10 is similar to FIG 1 for a second embodiment of embodiment of the invention.

002511 is a longitudinal section on a radial plane, the sleeve of the probe of Figure 10.

0026Figures 12 and 13 illustrate the manner in which are deployed barbs of the probe of Figure 10.

0027FIGS 1-9 refer to a first embodiment of the invention.

0028In Figure 1, reference 10 designates a rigid cylindrical body carrying the actual stimulation electrode 12 of a probe pacemaker, which shows a portion of the conductor hose 14. The other end of the probe (proximal end, not shown) has so classic in itself, a connector allowing the electrical connection to the remote pacemaker.

0029In a manner characteristic of the invention, there is provided a cylindrical sleeve 16 which caps the body 10 of the electrode (as shown eg Figure 4) and made for example of a type of silicone 47.80 ETRQ7 a Shore hardness of about 80, or a polyurethane Corethane type (trademark) of Corvita society. The sleeve 16 can slide freely, or with a slight friction (As explained below) on the body 10 in axial direction. A ring 18, preferably O, is snapped on a groove Section counterpart device 20 formed on the body 10, this ring 18 being connected to the front portion 22 of the sleeve by a plurality bridges 24, which will be explained below more in detail the role. The ring 18 has a necking force relative to the body 10 avoiding inadvertent detachment of the sleeve 16 during insertion of the probe to the cardiac cavity.

0030As can be seen in Figures 2 and 3, 24 (bridges which are on the drawing three in number, but this number is by no means limited to) have a central section with reduced width, condition original free (that illustrated in Figures 1 and 2) a concavity 26 facing the central axis of the sleeve (view from the left of Figure 3). The proximal ends 30 of the bridges, that is to say the ends directed towards the driver 14 are connected to the ring, due to its circular section 28 constitutes a hinge point allowing rotation of the proximal end 30 around the center of this section 28, as shown in successive views of Figure 3.

0031This rotation is against the own resilient bias the bridge of material 24, and causes an inversion of the concavity 26, thus maintaining the assembly in another stable state. In other words, Figure 3 views left and right are two stable states (stability resulting from the concavity of the parties proximal 30, rotated, respectively, towards the axis of the sleeve ring and away from this axis) and the central view corresponds to a intermediate position unstable.

0032The passage from one position to the other occurs as shown Figures 4 to 6.

0033When the probe is gradually approached to the wall 32 myocardial cavity (Figure 4), the body 10 and the sleeve 16 have the configuration illustrated in Figures 1 and 2 and Figure 3, for left. In this phase, the distal portion 22 of the probe protects the electrode 12 of the various friction, for example against other probes already installed.

0034The approach movement (arrow 34) continues until the distal end of the sleeve comes into contact with the wall 32 of the cavity (Figure 5).

0035Once docking thus produced, the further movement of axial advancement of the probe 34 induces a reaction force 36 of the distal end of the sleeve 16. This reaction 36 is transmitted to the flexible bridge 24 (arrow 38) due to the stiffness of the distal portion 22 of the sleeve. The buckling point is located to the place with the when the lower inertia, that is to say, the most narrowed portion bridges.

0036This has the effect of causing a rotation of the proximal ends bridges 24 around the ring 18 (shown schematically by the rotation arrow 40 in Figure 5) with a radial spacing of the correlative central part of the bridges 24 (arrow 42). The situation on the bridge Figure 5 essentially corresponds in cross section to the central view of the 3.

0037To prevent, by reaction, a decrease of ring movement would make it out of his throat 20, advantageously provides a shoulder 52 (Figures 4 to 6) behind said groove; in other words, the body 10 has proximal side of the groove a diameter greater than the diameter it distally.

0038The movement described continues until the abrupt change concavity of bridges 24 (Figure 6 and right side of Figure 3) which has the effect, first, to discover completely electrode 12 due to the complete translation 44 of the sleeve 16 and, on the other hand, allow the full deployment radial bridges 24, the part smallest radius of curvature will protrude radially with slight tilt in the proximal direction, taking the form of barbs which will be able to bear against the trabeculae of the cavity myocardial transmitting a result of action-reaction slight pressure of the electrode 12 against the wall 32.

0039The barbs are thus constituted by the two parts of each bridge 24, folded at the central area, where the section is the lower, as can be seen clearly on the perspective view of Figure 7.

0040Advantageously, it is expected to reduce the friction of the sleeve 16 on the body 10 by placing an appropriate lubricant such as a hydrogel, biocompatible course, between these two elements or one of them.

0041Moreover, advantageously, sleeve and body are designed so that in the sliding movement of the sleeve on the body, friction is low early in the race (Figures positions 4 and 5) and largest at the end of displacement (position of Figure 6) to lock the system in place, due to a resistance Additional overcome if one wanted to go back to the original position. In other words, it is desired to make the transition from the original position to the final position the less reversible as possible. This can be achieved for example by giving the one and / or the other of the cooperating parts a very slight taper and / or by providing light reliefs the inner surface of the sleeve 16 and / or on the outer surface of body 10.

0042Note also that inadvertent operation of the system during insertion is prevented because the bridges 24 are pressed against the body 10 of the probe by the elastic biasing of the walls Venous.

0043Finally, the sleeve material may advantageously contain radiopaque particles so that the practitioner can visually control the proper deployment of the barbs during surgery.

0044A major additional advantage of the invention resides in the ease of extraction of the probe.

0045Indeed, as illustrated in FIG 8, after several months 46 fibrosis is usually wrap the barbs formed by the folded 24 bridges, including the volume 48 between the two branches each folded beard. The connection between beard and fibrosis is therefore much stronger than the traditional configuration of a beard full, flat or cylindrical. Therefore, a pull exerted on the 50 body 10 of the probe cause almost invariably a tear fibrous tissue and therefore damage to the myocardial wall.

0046But advantageously, the ring 18, which is of such a material as polyurethane or silicone Shore hardness of 30-50, has a slight elasticity allowing a radial distension to the exit of the groove 20 and therefore the sliding of the probe, the entire sleeve Removable remaining in place, fully embedded in fibrosis.

0047It is thus possible with this dissociation of the sleeve with the body achieve without difficulty and without damage to the tissues withdrawal of the probe by a simple axial pulling movement exerted on the driver.

0048In an advantageous variant of the first embodiment, illustrated in Figure 9, the sensor head can provide a screw anchor 54 placed on the front part of the probe, in a manner itself known. The skirt 22 and plays a protective role of the vein wall at the time of insertion of the probe. Furthermore, the combination of this screw and the sleeve of the invention allows to be sure, a Once the screw is anchored to the myocardial wall, the barbs are deployed, that is to say that the sleeve is in the configuration Figure 7.

0049Figures 10 to 13 illustrate a second embodiment of the invention.

0050In this second embodiment, the movable member is no longer skirt 22, as in the first embodiment, but a ring 56 which may be of a shape and dimensions comparable to the ring 18, and is connected thereto by a plurality of bridges 24 which play the same function as in the first embodiment (where the same references digital converters are used for one and the other embodiment, These references correspond to similar elements, functionally similar).

0051Unlike the previous case where the movable member was located in forward (distally) from the retaining ring 18, in this second embodiment of the movable ring 56 is located backward (proximally) the same ring 18.

0052Therefore, the displacement of the movable member is no longer by a end biasing when coming into contact with the moving skirt the myocardial wall (that is to say a force exerted axially on the distal end of the sleeve) but by a back biasing, exerted by means of a sheath 58 (Figures 12 and 13) pushed onto the conductor to the probe (that is to say a force exerted axially on the proximal end of the sleeve). The progress towards distal (60 in Figure 12) of the sheath continues until contact the movable ring 56, which will therefore be pushed forward (Figure 13), thus causing bending of the bridges 24. The final position is determined by a peripheral groove 62 into which definitely fit the mobile ring 56, the bridges 24 then being full flexion in the same manner that it was explained for the first embodiment.

0053The operation ends with the removal of the sheath 58, which is advantageously a "peelable" disposable sheath, which can be split longitudinally in two halves as and its withdrawal

0054This second embodiment has the same vis-à-vis advantage extracting the previous embodiment, that the sleeve can easily become detached from the probe body to permit, In the same way, the extraction of the latter.