Patent Description:
It is known that active fixation leads comprise an extendable and retractable mechanism for deploying a helix electrode at a distal end of the lead. In the known extendable and retractable mechanism, the helix electrode is electrically connected to and supported by an electrically conductive driver shaft movably disposed within a distal housing portion of the lead. The helix electrode is thus electrically connected to a distal coil conductor of the lead by means of the conductive driver. The helix electrode could be in intermittent contact with an internal wall of the distal housing portion of the lead in which is it movably housed.

The distal housing portion of the lead is usually a cylindrical molded plastic part. However, the distal housing portion of the lead may be provided with metallic part(s).

The presence of metal part in the distal housing portion of the lead involves that if the helix electrode and the metallic part of the housing are not continuously electrically connected, electrical chatter noises may be generated. Indeed, chatter noise may result from the intermittent contacts of these metallic parts of the lead, especially as the helix electrode or the distal metallic part of the housing is in contact with blood, being an ionic solution. Chatter noise is a parasite electrical signal that can cause the delivery of inappropriate therapy or shock.

For addressing the electrical chatter noise problem occurring between a metallic housing collar of the lead and the helix electrode, the document <CIT>discloses the use of a compression metallic coil spring or a "ball seal" type contact spring. According to the document <CIT>, such spring is positioned around the conductive driver, thereby generating an electrical contact between the spring and the driver, the driver being electrically connected to the helix electrode and the distal coil conductor of the lead. In particular, in the document <CIT>, a garter spring (i.e. a circular spring) is housed in the annular recess of an annular track member disposed between the driver and a tubular conductive coupling. The annular track member according to the document <CIT> allows radially compressing the garter spring over the entire periphery of the driver.

However, the radial compression of the garter spring over the entire periphery of the driver increases the friction between the spring and the driver, which may generate parasitic mechanical effects. Indeed, the mechanical friction between the spring and the driver can affect the smoothness of the driver's movement, and makes the driver moves in a jerky manner. Such parasitic friction will thus jeopardize the quality of the helix screw deployment.

Moreover, in the known pacing and/or defibrillation lead, the distal housing portion of the lead comprising the retractable fixation mechanism and an anode provided at the distal end of the lead constitutes the most rigid portion of the distal part of the lead. In particular, there is the type of lead wherein said "rigid" portion is a one-piece portion completely rigid and about <NUM> to <NUM> long. There is also a type of lead wherein said "rigid" portion actually comprises two distinct rigid sections separated by a more flexible portion having a length between <NUM> and <NUM>.

The presence of a flexible portion, as mentioned above with respect to the second type of lead, is generally preferred by clinicians because it allows facilitating the implantation of the lead, in particular in the neighboring of the heart chambers and for passing the tricuspid valve. On the other hand, because the short flexible portion (having a length of <NUM> to <NUM>) is arranged between two more rigid portions of the lead, it may impact the long-term reliability of the lead. Indeed, the mechanical stress generated by the cyclic cardiac contractions is mostly absorbed by the short flexible section of <NUM> and <NUM> length.

Further known implantable pacing and/or defibrillation lead are shown in <CIT>, <CIT>, <CIT>, <CIT> and <CIT>.

Hence, an object of the present invention is to provide a pacing and/or defibrillation lead comprising a retractable fixation mechanism wherein the rigid distal portion of the lead has a reduced length compared to that of the leads from the state of the art, in order to facilitate its placement.

There is also a need for improving the sealing properties of the known pacing and/or defibrillation lead wherein the distal housing portion of the lead comprises the retractable fixation mechanism. Indeed, fluid, like blood, can enter the lumen of the distal housing portion of the lead via the distal opening through which the fixation mechanism can be extended and retracted. As blood is an ionic solution, surface and/or volume corrosion can occur inside the distal end of the lead.

Hence, another object of the present disclosure is to improve the sealing properties of the distal end portion of an active fixation lead and, in particular, provide as sealing solution that allows an easy assembly of the lead.

The present disclosure relates to of an implantable pacing and/or defibrillation lead. Said lead extending from a proximal end to a distal end, wherein the proximal end of the lead is configured to be connected to an implantable medical device, the lead comprising: - an active fixation electrode at the distal end of the lead, which is mechanically and electrically coupled to a conductive driver shaft moveably arranged in a distal housing portion of the lead, wherein the active fixation electrode is movable from a retracted position in which the active fixation electrode is completely housed inside the distal housing, to an extended position, in which the active fixation electrode extends in a distal direction at least partially beyond the distal housing portion, and - an electrically conductive compression spring. The lead further comprises a guiding member arranged inside the distal housing portion and comprising a tubular body electrically connected with the distal housing portion, wherein the conductive driver shaft is slideably arranged through a lumen extending through the tubular body, wherein the tubular body further comprises a radial opening in communication with the lumen, and wherein the electrically conductive compression spring is at least partially radially arranged around the tubular body and its radial opening, such that the electrically conductive compression spring is forced by its restoring force against the conductive driver shaft.

Hence, the occurrence of chatter noise can be avoided by means of a continuous and stable electrical contact provided between the active fixation electrode and the distal housing portion that brings the active fixation electrode and the distal housing portion onto the same electrical potential. The continuous electrical contact is realized by the electrically conductive compression spring forced by its restoring force against the conductive driver shaft.

The spring provides multi-point contacts with the conductive driver shaft at the radial opening by means of the spring's individual coils. As the electrically conductive compression spring can only contact the conductive driver shaft at the radial opening of the tubular body, friction between the electrically conductive compression spring and the conductive driver shaft may only occur at the radial opening, and not over the entire periphery of the conductive driver shaft. Thus, in comparison with the state of the art, friction can be advantageously reduced. As less unwanted mechanical friction is generated than in the state of the art, the quality of the active fixation electrode is improved and a smooth deployment of the active fixation electrode can be achieved.

For sake of completeness, it is noted that the expression "conductive driver shaft" refers to an electrically conductive driver shaft.

The implantable pacing and/or defibrillation lead described herein can be further improved according to various examples as shown below.

For example, the electrically conductive compression spring can be a closed coiled helical spring.

It allows advantageously reducing the size of the spring while facilitating the assembly of the lead as the closed coiled helical spring can be maintained around the tubular body without the need of additional retaining means. The successive coils of the spring provide multi-point contacts with the conductive driver shaft at the radial opening, therefore ensuring a redundancy of the electrical contacts.

For example, the electrically conductive compression spring can be an open coiled helical spring comprising two free-ends.

Hence, the solution for avoiding chatter noise can advantageously be implemented with different type of springs.

For example, at least a portion of the tubular body provided with the radial opening can have an outer radius greater than an inner radius of the electrically conductive compression spring at its rest state.

The radial dimension difference causes the spring to be forced against the conductive driver shaft by its restoring force and thus ensures the electrical contact.

For example, the radial opening can have an opening angle comprised between <NUM>° and <NUM>°, in particular between <NUM>° and <NUM>°, in a cross section of the tubular body perpendicular to a direction of extension of the lead.

The dimension of the radial opening is adapted to provide an opening allowing the spring to generate a restoring force sufficient to provide a stable contact against the conductive driver shaft.

For example, the radial opening can have a width along a direction of extension of the lead greater than the extension of the electrically conductive compression spring in that direction.

Hence, sufficient space is provided to reliably bring the spring into contact with the conductive driver shaft as the spring can freely retract onto the driver shaft when positioned in the radial opening.

For example, the inner diameter of the distal housing portion can be larger than the diameter of the electrically conductive compression spring at least partially radially arranged around the tubular body and its radial opening.

Hence, in the lead, because of their dimension's differences, the spring is not compressed by the distal housing portion, which would lead to unwanted larger friction.

For example, the tubular body can have at least one chamfered edge at the radial opening.

The presence of chamfered edge prevents damaging the spring, in comparison with sharp edge. Thereby, the robustness and the lifetime of the lead can be improved.

For example, the tubular body can comprise at least - a first portion provided with the radial opening and a portion of the tubular body contacting the distal housing portion, and - a second portion extending from a distal end of the tubular body to the first portion, and wherein a sealing means can be provided at the second portion to seal the first portion of the tubular body from the distal end of the lead.

Hence, the first portion of the tubular body, which comprises the spring, can be advantageously sealed against fluids like blood, being an ionic solution. It allows preventing surface and/or volume corrosion, in particular at the electrically conductive compression spring.

For example, the tubular body of the guiding member can be mechanically and electrically connected to the distal housing portion by means of a welding, and/or by means of a crimping means and/or a heat shrinked means arranged to maintain the tubular body in electrical and mechanical contact with the distal housing.

It further allows providing a lead easy to assemble, thereby improving the manufacturing efficiency.

It further allows establishing a stable electrical connection between the tubular body of the guiding member and the distal housing portion.

The present disclosure also relates to a method for assembling an implantable pacing and/or defibrillation lead according to one of the above-mentioned examples.

Said method comprises the steps of: a) providing the electrically conductive compression spring around the tubular body of the guiding member at the radial opening such that a portion of the electrically conductive compression spring is partially deflected inside the lumen due to its restoring force, then b) inserting the conductive driver shaft through the lumen of the conductive guiding member thereby pushing at least partially the compression spring outside the lumen so as to provide an electrical connection between the electrically conductive compression spring and the conductive driver shaft, and then c) mechanically and electrically connecting the tubular body of the guiding member to the distal housing portion of the lead.

The method allows providing a simplified and reliable assembly process.

For example, step b) can further comprise providing a sealing means at the distal end of the tubular body to seal it from the distal end of the lead.

It allows sealing the tubular body from the distal end of the lead against fluids like blood, being an ionic solution. It thus allows preventing surface and/or volume corrosion, in particular at the electrically conductive compression spring.

For example, step c) can comprise welding the tubular body to the distal housing portion of the lead, in particular by laser welding.

It allows establishing a stable electrical connection between the tubular body of the guiding member and the distal housing portion.

The present invention provides a implantable pacing and/or defibrillation lead according to claim <NUM>.

It is noted that the above-mentioned sleeve is a distal housing of portion of the lead.

The annular electrode of the lead body is superimposed to the sleeve. In other words, the annular electrode is arranged above the sleeve in a radial direction of the lead.

As a result, the rigid portion of the lead is advantageously compacted axially, i.e. along the longitudinal axis of the lead, which allows the length of the rigid portion to be reduced compared to the known leads.

In fact, two functions of the lead are superimposed because the annular electrode, which has an anode function for detection and/or stimulation is superimposed, i.e. arranged above, the sleeve comprising an electrode, which has a cathode function for detection and/or stimulation. The electrodes constitute so-called "rigid" portions of the lead. In the case of leads with active fixation, the sleeve comprises an electrode in the form of a retractable screw, which has a combined function of cathode for detection and/or stimulation and means of fixation to a tissue. The structure of the lead thus allows a plurality of lead functions to be arranged in a way that the length of the rigid portion of the lead can be reduced (i.e. along the longitudinal axis of the lead), thereby facilitating its implantation and placement within the body of a patient.

It also allows avoiding the presence of a more flexible portion between two rigid portions, as known from the leads according to the state of the art. Thus, the lead according to the present invention is more reliable and robust over time.

The implantable pacing and/or defibrillation lead for addressing the second object of the invention can be further improved according to various advantageous embodiments.

The electrically insulating sheath is arranged between the annular electrode and the sleeve in a radial direction of the lead. The annular electrode is thus superimposed to the sleeve, so that the annular electrode is arranged above the sleeve, but the annular electrode is not directly arranged on the sleeve.

The electrically insulating sleeve allows the isolation of the anode pole from the cathode pole. The use of a sheath on the sleeve has the advantage of being a compact structural solution.

In addition, the thermo-shrink formation avoids the presence of an air gap between the sleeve and the sheath and can easily be adapted to any shape.

The use of Teflon has the technical effect of improving the electrical insulation performance of the sheath because the efficiency of Teflon (tetra-fluoroethylene) in terms of electrical insulation is particularly satisfactory.

By using a metallic material for the sleeve, the wall thickness of the sleeve can be reduced in comparison to the thickness obtained by using a plastic material. Thus, either the diameter of the sleeve can be advantageously reduced, or the internal space of the sleeve can be enlarged, thus allowing the insertion of a fastening screw of larger diameter.

According to one embodiment, a proximal end of the sleeve can be accommodated within the distal end of the lead body and can comprise a shoulder.

The shoulder of the proximal end of the sleeve provides an axial stop on which the anode of the lead body can rest and thus mechanically hold the sleeve to the lead body.

According to one embodiment, the annular electrode can be attached to the sleeve by clamping or crimping.

Thus, the proximal end of the sleeve with the shoulder can be mechanically held to the lead body without the need for welding. This simplifies the assembly of the lead.

According to one embodiment, the annular electrode can be clamped or crimped in at least two distinct areas of the sleeve.

Thus, it is not necessary to crimp or clamp the annular electrode around its entire circumference to ensure the mechanical connection between the sleeve and the lead body. This further simplifies the assembly while ensuring a reliable mechanical connection over time. According to one embodiment, the implantable lead can further comprise a retaining ring welded or soldered to the annular electrode of the distal end of the lead body and arranged, along a radial direction of the lead, at least partially between the annular electrode and the sleeve, the retaining ring can further comprise at one end thereof a shoulder, said shoulder being arranged, along a longitudinal direction of the lead, between the annular electrode and the sleeve.

The use of a retaining ring offers an alternative way of securing the sleeve to the lead body.

According to one embodiment, the annular electrode can have a surface of at least <NUM> square millimeters.

This anode surface allows preserving sensing functions compatible with atrial and ventricular positioning.

According to one embodiment, the implantable lead can comprise an electrically insulating adhesive, in particular silicone adhesive or glue, between the distal end of the lead body and the proximal end of the sleeve accommodated in the distal end of the lead body.

Thus, the electrical isolation between the cathode and anode can be further improved, as the adhesive provides an additional sealing barrier.

In addition, the introduction of glue minimizes any relative movement between the sleeve and the distal end of the lead body.

The present invention also provides a method for assembling an implantable lead as defined in claim <NUM>.

As a result, the rigid portion of the lead is advantageously compacted axially (i.e. along the longitudinal axis of the lead), which makes it possible to reduce the length of the rigid portion compared to known leads.

In fact, two functions of the lead are superimposed because the annular electrode, which has an anode function for detection and/or stimulation is superimposed to, i.e. arranged above, the sleeve comprising an electrode which has a cathode function for detection and/or stimulation. The electrodes constitute so-called "rigid" portions of the lead. In the case of leads with active fixation, the sleeve comprises an electrode in the form of a retractable screw, which has a combined function of cathode and means of fixation to a tissue. The structure of the lead thus allows a plurality of functions of the lead to be arranged in a way to reduce the length (i.e., along the longitudinal axis of the lead) of the rigid portion of the lead, thereby facilitating its implantation and placement within the body of a patient.

It allows also avoiding the presence of a more flexible portion between two rigid portions, as known from the lead of the state of the art. Thus, the lead according to the present invention is more reliable and robust over time.

The electrically insulating sleeve allows the insulation of the anode pole (i.e. the annular electrode) from the cathode pole (i.e. the electrode in the sleeve). The use of a sheath on the sleeve has the advantage of being a compact structural solution.

In addition, the thermo-shrink formation allows avoiding the presence of an air gap between the sleeve and the sheath and can easily be adapted to any shape.

According to one embodiment, the method can further comprise a step of clamping or crimping the annular electrode to the sleeve.

According to one embodiment, step <NUM>) of the method can further comprise: welding a retaining ring to the annular electrode of the lead body, and inserting the sleeve into the lead body such that the retaining ring is, in a radial direction of the lead, at least partially between the annular electrode and the sleeve, and such that a shoulder provided at one of the ends of the retaining ring is arranged, in a longitudinal direction of the lead, between the annular electrode and the sleeve.

The use of a retaining ring provides an alternative way of securing the sleeve to the lead body. According to one embodiment, the method can further comprise a step of introducing electrically insulating adhesive between the distal end of the lead body and the portion of the sleeve accommodated in the distal end of the lead body.

In addition, the introduction of glue allows minimizing any relative movement between the sleeve and the distal end of the lead body.

The present disclosure also relates to an implantable pacing and/or defibrillation lead, said lead extending from a proximal end to a distal end, wherein the proximal end of the lead is configured to be connected to an implantable medical device. The lead comprises: an active fixation electrode at the distal end which is mechanically and electrically coupled to a conductive driver shaft moveably arranged in a distal housing portion of the lead, wherein the active fixation electrode is movable from a retracted position in which the active fixation electrode is completely housed inside the distal housing portion, to an extended position, in which the active fixation electrode extends in a distal direction at least partially beyond the distal housing portion. The lead further comprises: - a guiding member arranged inside the distal housing portion and comprising a tubular body electrically connected with the distal housing portion, wherein the conductive driver shaft is slideably and rotatably arranged through a lumen extending through the tubular body, and - a sealing means for sealing the distal housing portion from the distal end of the lead. The sealing means comprises a sealing ring having at least two portions with respect to a central longitudinal axis of said sealing ring, a first portion of the sealing ring being arranged around the conductive driver shaft and a second portion of the sealing ring being arranged around the tubular body, the first portion of the sealing ring having an external diameter strictly less than an internal diameter of the distal housing portion, and the first portion of the sealing ring having an internal diameter strictly less than an external diameter of the conductive driver shaft, and the second portion of the sealing ring having an external diameter strictly more than the internal diameter of the distal housing portion.

Hence, the dimensions of the sealing ring of the sealing means allows avoiding fluidic communication from the distal end of the lead wherein blood can enter the distal housing portion. It thus allows at least partially sealing the distal housing portion, in particular wherein metallic elements may be housed, such as an electrically conductive spring for providing an electrical connection. The sealing means thus decrease the risk of surface and/or volume corrosion, in particular between a fluid and such an electrically conductive spring.

This is achieved thanks to the dimensions of the sealing ring, the first portion of which having dimensions allowing a rotation and a translation of the conductive driver shaft within the sealing ring while forming a seal at an interface between the conductive driver shaft and the sealing ring.

It is further achieved thanks to the dimensions of the second portion of the sealing ring forming a seal at an interface between the internal distal housing portion and the sealing ring.

As the first portion of the sealing ring have an external diameter strictly less than an internal diameter of the distal housing portion, there is no stress applied on the sealing ring by the distal housing portion at the first portion of the sealing ring. Hence, at the first portion, the sealing ring is only deformed, in particular elastically deformed, at the interface between the first portion and the conductive driver shaft.

For example, the percentage difference of diameter between the external diameter of the first portion of the sealing ring and the internal diameter of the distal housing portion can be comprised between <NUM> % and <NUM>%, particular between <NUM>% and <NUM>%.

Hence, it allows reducing the friction between the sealing ring and the distal housing portion, so as to not hinder the rotation and the translation of the conductive driver shaft with respect to the sealing means at the first portion of the sealing ring. By avoiding friction, the active fixation electrode can be deployed more smoothly, without unwanted jerking motion of the conductive driver shaft.

Such range can render a fluidic communication possible at the interface between the distal housing portion and the first portion of the sealing ring. The sealing properties are however ensured at the interface between the conductive driver shaft and the first portion of the sealing means, and at the interface between the distal housing portion and the second portion of the sealing means.

For example, the percentage difference between the internal diameter of the first portion of the sealing ring and an external diameter of the conductive driver shaft be comprised between <NUM>,<NUM> % and <NUM>%, in particular between <NUM>% to <NUM>%.

The above-mentioned range of percentage difference allows the conductive driver shaft to rotate and slide with respect to the sealing ring while preventing fluid communication at the interface between the conductive driver shaft and the first portion of the sealing ring.

For example, the percentage difference between the external diameter of the second portion of the sealing ring and the internal diameter of the distal housing portion can be comprised between <NUM>,<NUM> % and <NUM>%, in particular between <NUM>% and <NUM>%.

The above-mentioned range of percentage difference allows forming a seal and preventing fluid communication at the interface between the distal housing portion and the second portion of the sealing ring.

For example, the internal diameter of the first portion of the sealing ring can be less than the internal diameter of the second portion of the sealing ring.

It allows providing a lead wherein the dimension of the first portion is adapted for receiving the conductive driver shaft while the dimension of the second portion is adapted for receiving the tubular body wherein the conductive driver shaft is slideably and rotatably arranged through the lumen of the tubular body.

For example, a distal end of the tubular body can be provided with an external radially protruding shoulder, said external radially protruding shoulder being form-fitted into a corresponding internal radial recess of the sealing ring of the sealing means.

The form-fitted connection allows locking the seal means to the tubular body, in particular a friction-locked connection.

For example, the internal radial recess of the sealing ring can be provided at a junction between the first portion and the second portion of the sealing ring.

Hence, a mechanically stable retention by the form-fitted connection can be obtained.

For example, the first portion of the sealing ring can have a rounded edge along its internal diameter.

It allows reducing the friction generated between the sealing ring and the distal housing portion, so as to not hinder the rotation and the translation of the conductive driver shaft with respect to the sealing means at the first portion of the sealing ring.

For example, the sealing means can be integrally formed in one-piece. Hence, the sealing means can be easily manufacturing and assembled to the lead, thereby reducing the assembly time and the assembly cost.

For example, the sealing means can be made of rubber, in particular of silicone, and can have a Shore hardness comprised between <NUM> to <NUM> Shore A.

The stress-strain behavior of a rubber sealing means can be linked to its Shore hardness. The selection of the Shore hardness in the range <NUM>-<NUM> Shore A allows ensuring that a sufficient compressive force is exerted on the flexible rubber sealing means in the distal housing portion. The Shore hardness of the rubber sealing means is thus adapted to provide the sealing properties in the arrangement of the sealing means inside the distal end housing.

The present disclosure further relates to an implantable pacing and/or defibrillation lead, said lead extending from a proximal end to a distal end, wherein the proximal end of the lead is configured to be connected to an implantable medical device, the lead comprising: an active fixation electrode at the distal end which is mechanically and electrically coupled to a conductive driver shaft moveably arranged in a distal housing portion of the lead, wherein the active fixation electrode is movable from a retracted position in which the active fixation electrode is completely housed inside the distal housing portion, to an extended position, in which the active fixation electrode extends in a distal direction at least partially beyond the distal housing portion, and an electrically conductive compression spring, further comprising: a guiding member arranged inside the distal housing portion and comprising a tubular body electrically connected with the distal housing portion, wherein the conductive driver shaft is slideably and rotatably arranged through a lumen extending through the tubular body, wherein the tubular body further comprises a radial opening in communication with the lumen, and wherein the electrically conductive compression spring is at least partially radially arranged around the tubular body and its radial opening, such that the electrically conductive compression spring is forced by its restoring force against the conductive driver shaft, and a sealing means for sealing the distal housing portion from the distal end of the lead, the sealing means comprising a sealing ring having at least two portions with respect to a central longitudinal axis of said sealing ring, a first portion of the sealing ring being arranged around the conductive driver shaft and a second portion of the sealing ring being arranged around the tubular body, the first portion of the sealing ring having an external diameter strictly less than an internal diameter of the distal housing portion, and the first portion of the sealing ring having an internal diameter strictly less than an external diameter of the conductive driver shaft, and the second portion of the sealing ring having an external diameter strictly more than the internal diameter of the distal housing portion.

Additional features and advantages of the present invention will be described with reference to the drawing. In the description, reference is made to the accompanying figure that is meant to illustrate the invention. It is understood that the scope of the present invention is defined by the appended claims.

<FIG> depicts a cross-sectional view of an implantable cardiac pacing lead <NUM> according to a first example. In one example, it may be a defibrillation lead.

The pacing lead <NUM> shown in <FIG> is a retractable screw lead. In another example, it may be a passive fixation lead comprising barbs arranged radially around the lead body with a stimulation (pacing) electrode at the distal end.

The lead <NUM> comprises a substantially cylindrical lead body <NUM> that extends longitudinally along an axis A, which constitutes an axis of revolution.

The lead body <NUM> comprises a proximal end (not shown in <FIG>) configured for connection to an implantable medical device (not shown in <FIG>) and a distal end <NUM> that is opposite to said proximal end.

The distal end <NUM> of the lead body <NUM> comprises an annular electrode <NUM>. The annular electrode <NUM> forms an anode of the lead <NUM>. The annular electrode <NUM> and the lead body <NUM> have substantially the same diameter.

As shown in <FIG>, the distal end <NUM> of the lead body <NUM> is terminated by the annular electrode <NUM>.

Between the distal end <NUM> and the proximal end of the lead <NUM>, coiled electrical conductors <NUM> are housed within the lead body <NUM>. In particular, the electrical conductors <NUM> allow the annular electrode <NUM>, i.e., the anode, to be electrically connected to one pole of the implantable medical device connector (not shown in <FIG>).

The lead <NUM> further comprises a sleeve <NUM> in which a retractable fixation screw <NUM> is housed. The retractable attachment screw <NUM> forms a cathode of the lead <NUM>. The retractable fixation screw <NUM> is a helical screw made of conductive material, connected through a metal tip <NUM>, i.e. an electrically conductive driver shaft <NUM>, to an internal conductor <NUM>. The coiled conductor <NUM> provides electrical continuity between the retractable fixation screw <NUM> (which acts as a sensing and stimulation electrode) and a generator located at the proximal end (not shown in <FIG>) of the lead <NUM>.

The sleeve <NUM> is substantially cylindrical in shape with the same diameter as the annular electrode <NUM> and the lead body <NUM>.

The sleeve <NUM> comprises a distal end <NUM> provided with an opening <NUM> dimensioned such that the retractable fixation screw <NUM> is configured to be deployed along a direction D1 out of the sleeve <NUM> through said opening <NUM>. The opening <NUM> in the distal end <NUM> is provided with an edge <NUM> around the entire circumference of the sleeve <NUM>. The edge <NUM> is substantially rounded and therefore is not sharp or cutting. A sealing means <NUM> (visible in <FIG> but only annotated in <FIG>) is provided in the sleeve <NUM> to at least partially seal the lead <NUM> from the distal end <NUM>.

The sleeve <NUM> comprises, opposite to its distal end <NUM>, a proximal end <NUM>. At the proximal end <NUM>, a mouthpiece or guiding member <NUM> of the lead <NUM> is bordered around its entire circumference by a shoulder <NUM>.

The sleeve <NUM> is partially accommodated at its proximal end <NUM> within the distal end <NUM> of the lead body <NUM> such that the annular electrode <NUM> of the lead body <NUM> is superimposed on the sleeve <NUM>, i.e., the annular electrode <NUM> is disposed above the sleeve <NUM> along a radial direction R of the lead.

As it will be described below, the annular electrode <NUM> is not disposed directly on the sleeve <NUM> due to the presence of an electrically insulating sheath (shown by the reference sign <NUM>) disposed along the radial direction R of the lead between the annular electrode <NUM> and the sleeve <NUM>.

The structure and geometry of the sleeve <NUM> is further appreciated in the drawings of <FIG> described below, which illustrate the sleeve <NUM> outside the lead body <NUM>.

In one example wherein the lead is a passive fixation lead, the stimulation electrode may have a substantially solid cylinder shape and may be at least partially housed within the sleeve <NUM> such that the stimulation electrode, like the retractable fixation screw <NUM>, extends along the axis A. The distal end of the stimulation electrode can be a substantially smooth, flat or curved surface configured to contact tissue. Such a lead is then held in place by means of barbs arranged radially around the lead body.

The metal tip <NUM>, i.e. the electrically conductive driver shaft <NUM>, and the inner conductor <NUM> are housed in the lead body <NUM> and are arranged, in particular partially arranged, within the circumference <NUM> defined by spiral electrical conductors <NUM>.

Thus, two functions of the lead <NUM> are superimposed along a radial direction R of the lead: a portion of the anode <NUM> (sensing/stimulation function) is superimposed with the sleeve <NUM> comprising the retractable screw <NUM> (fixation and sensing/stimulation function). As a result, the rigid portion <NUM> of the lead <NUM>, i.e., the portion <NUM> that extends from the distal end <NUM> of the sleeve <NUM> to the junction <NUM> between the annular electrode <NUM> and the lead body <NUM>, is advantageously compacted axially along the axis A (i.e., along the longitudinal axis of the lead <NUM>), thereby allowing reducing the length of the rigid portion <NUM> as compared to that of known leads. This also makes it possible to avoid the presence of a flexible portion between two rigid portions, as proposed by some leads known from the state of the art.

The sleeve <NUM> is partially accommodated in the distal end <NUM> of the lead body <NUM> such that the distance L1 between the cathode <NUM> and the anode <NUM> is at least <NUM> millimeters. This distance L1 allows to preserve sensing functions that are compatible with an atrial and ventricular implantation of the lead <NUM>.

In addition, the anode <NUM> preferably has a surface area of at least <NUM> square millimeters to preserve sensing and pacing functions compatible with an atrial and ventricular implantation of the lead <NUM>.

The sleeve <NUM> is made of a metallic material. The use of a metallic material for the sleeve <NUM> allows the thickness "e20" of the wall of the sleeve <NUM> to be reduced in comparison to the thickness involved by the use of a plastic material. Thus, either the diameter d20 of the sleeve <NUM> can be advantageously reduced, or the internal volume of the sleeve can be enlarged, thereby allowing the insertion of a fixation screw <NUM> of larger diameter.

The conductive elements of the sleeve <NUM>, i.e., the retractable fixation screw <NUM>, the electrically conductive driver shaft <NUM>, and the inner conductor <NUM>, are insulated from the conductive elements (i.e. the coiled electrical conductors <NUM>) connected to the annular electrode <NUM> of the lead body <NUM> by a cylindrical tube <NUM> made of an electrically insulating material.

In addition, in order to electrically isolate the cathode (i.e. the retractable fixation screw <NUM>) from the anode (i.e. the annular electrode <NUM>) at the overlap area <NUM> of the sleeve <NUM> at the distal end <NUM> of the lead body <NUM>, an electrically insulating sheath <NUM> is disposed on the sleeve <NUM>. The electrically insulating sheath <NUM> is disposed between the annular electrode <NUM> and the sleeve <NUM> along the radial direction of the lead <NUM>. The electrically insulating sheath <NUM> may be a Teflon sheath heat shrunk onto the sleeve <NUM> at the overlap area <NUM>.

The electrically insulating sleeve <NUM> allows the isolation of the pole constituted by the anode <NUM> from the pole constituted by the cathode <NUM>, in a radial direction R of the lead body <NUM>. The use of a sheath <NUM> arranged on the sleeve <NUM> has the advantage of being a structurally compact solution. Indeed, the sheath <NUM> can be arranged in the residual space between the sleeve <NUM> and the lead body <NUM> superimposed on the sleeve <NUM>, which is typically less than <NUM> microns.

In addition, the heat shrink formation eliminates the need for an air gap between the sleeve <NUM> and the sheath <NUM> and allows for easy adaptation to any shape.

Moreover, the efficiency of Teflon (tetra-fluoroethylene) in terms of electrical insulation is particularly satisfactory.

However, the use of a Teflon sheath <NUM> does not allow the use of known conventional adhesives such as silicone or polyurethane to ensure the mechanical connection between the sleeve <NUM> and the lead body <NUM>, as Teflon constitutes a non-stick (i.e. non-adhesive) coating. Therefore, as shown in <FIG>, the annular electrode <NUM> is deformed, by clamping or crimping, to form a recess <NUM>. This recess <NUM> abuts on the shoulder <NUM> of the mouthpiece <NUM> of the sleeve <NUM>. In other words, the shoulder <NUM> provides an axial stop for the anode <NUM>, which mechanically holds the sleeve <NUM> to the lead body <NUM>.

As illustrated in <FIG>, which will be further described below, the anode <NUM> may comprise at least two recesses <NUM>, preferably three, distributed distinctly from one another around the circumference of the annular electrode <NUM>. This eliminates the need to crimp the entire circumference of the anode <NUM>, thereby preserving the underlying electrically insulating sheath <NUM>, in particular the Teflon coating.

<FIG> illustrates a second example for realizing the mechanical connection between the sleeve <NUM> and the lead body <NUM>.

The elements with the same numerical references used for the description in <FIG> refer to the same elements and will not be described again in detail.

In the second example, the anode <NUM> is not plastically deformed.

As illustrated in <FIG>, the lead <NUM> further comprises a retaining ring <NUM>. The retaining ring <NUM> is welded to the annular electrode <NUM>. In particular, the retaining ring <NUM> is welded to the inner wall <NUM> of the annular electrode <NUM>. The retaining ring <NUM> comprises at its distal end <NUM> a shoulder <NUM>.

According to the second example, the retaining ring <NUM> is arranged, in a radial direction R of the lead, partially between the annular electrode <NUM> and the sleeve <NUM>. Because of the presence of the shoulder <NUM>, the retaining ring <NUM> is arranged in a longitudinal direction of the lead <NUM>, i.e., along the axis A, between the annular electrode <NUM> and the sleeve <NUM>. As shown in <FIG>, the shoulder <NUM> abuts the distal end <NUM> of the lead body <NUM> in a direction parallel to the axis A.

The use of a retaining ring <NUM> provides an alternative to the first embodiment for securing the sleeve <NUM> relative to the lead body <NUM>.

In both the first example (shown in <FIG>) and the second example (shown in <FIG>), electrically insulating adhesive <NUM>, in particular silicone adhesive, may be introduced between the distal end <NUM> of the lead body <NUM> and the proximal end <NUM> of the sleeve <NUM> accommodated in the distal end <NUM> of the lead body <NUM> (i.e., the portion of the sleeve <NUM> covered by the electrically insulating sheath <NUM>). This electrically insulating adhesive <NUM> may be introduced via a through-hole <NUM> provided in the lead body <NUM> at the annular electrode <NUM> (see <FIG>).

Thus, electrical isolation between cathode <NUM> and anode <NUM> can be further improved, as the adhesive <NUM> provides an additional sealing barrier.

In addition, the introduction of adhesive <NUM> allows minimizing any residual relative movement between the sleeve <NUM> and the distal end <NUM> of the lead body <NUM>.

The electrically insulating adhesive <NUM> provides an adhesive seal <NUM> that ensures an axial locking by compensating the assembly clearances. In addition, the adhesive seal <NUM> provides a flexible stop between the proximal end <NUM> (opposite the distal end <NUM> along the axis A) of the retaining ring <NUM> and the shoulder <NUM> to prevent a progressive piercing of the insulating sleeve <NUM>.

As in the first example, the sealing means <NUM> is provided in the sleeve <NUM> to at least partially seal the lead <NUM> from the distal end <NUM>.

A method for assembling a stimulation lead <NUM> according to the first example is described below with reference to <FIG>.

<FIG> shows a cross-sectional view of the sleeve <NUM> in which the retractable fixation screw <NUM> is housed. The electrically insulating sleeve <NUM> is positioned around the sleeve <NUM> so as to at least partially cover the retractable fixation screw <NUM>, the electrically conductive drive shaft <NUM>, the mouthpiece <NUM> and the shoulder <NUM>, and the coiled electrical conductors <NUM>.

<FIG> depicts a next step in the method in which the electrically insulating sheath <NUM> is heat shrunk to the sleeve <NUM>. The electrically insulating sleeve <NUM> is thereby deformed to conform to the shape of the outer circumference of the sleeve <NUM>.

<FIG> depicts a next step of the method. The proximal end <NUM> of the sleeve <NUM>, opposite to the distal end <NUM> along the axis A, is provided with the electrically insulating thermoformed sheath <NUM> and is accommodated in the lead body <NUM> by the distal end <NUM> of the lead body <NUM> along an insertion direction D2 parallel to the longitudinal axis A of the lead <NUM>. As described with respect to <FIG>, the distal end <NUM> of the lead body <NUM> comprises the annular electrode <NUM>.

<FIG> depicts a next step in the method in which the sleeve <NUM> has been partially accommodated along the direction of insertion D2 into the lead body <NUM> until the shoulder <NUM> of the mouthpiece <NUM> abuts an inner wall <NUM> of the annular electrode <NUM>. Electrical insulation between the annular electrode <NUM> and the retractable fixation screw <NUM> is provided by the electrically insulating thermoformed sheath <NUM>.

<FIG> depicts a cross-sectional view of a subsequent method step in which the annular electrode <NUM> is plastically deformed by clamping or crimping to form elongated recesses <NUM> that extend in a direction parallel to the axis A of the lead <NUM>.

<FIG> illustrates the lead <NUM> in a three-dimensional schematic view. Two recesses <NUM> are visible around the circumference of the annular electrode <NUM> in <FIG>.

As explained with reference to <FIG>, each recess <NUM> abuts against shoulder <NUM> of the mouthpiece <NUM> of the sleeve <NUM>, i.e., shoulder <NUM> provides an axial stop for the anode <NUM>, which mechanically holds the sleeve <NUM> to the lead body <NUM>.

<FIG>, which corresponds to <FIG>, depicts a subsequent method step in which electrically insulating adhesive <NUM>, in particular silicone adhesive, is introduced through the through-hole <NUM> of the annular electrode <NUM>.

This insulating adhesive <NUM> disposed between the distal end <NUM> of the lead body <NUM> and the proximal end <NUM> of the sleeve <NUM> accommodated in the distal end <NUM> of the lead body <NUM> (i.e., the portion of the sleeve <NUM> covered by the electrically insulating sheath <NUM>) improves the electrical isolation between the cathode <NUM> and the anode <NUM> by providing an additional sealing barrier.

Steps of a method for assembling a stimulation lead <NUM> according to the second example are described below with reference to <FIG>.

The elements with the same numerical references used for the description of <FIG> refer to the same elements and will not be described again in detail.

<FIG> shows a cross-sectional view of the sleeve <NUM> in which the retaining ring <NUM> has been welded at the interface <NUM>, between the distal end <NUM> of the annular electrode <NUM> of the lead body <NUM> and the shoulder <NUM>. The interface <NUM> thus extends along the radial direction R.

In this step of the method shown in <FIG>, the sleeve <NUM> has further been inserted into the lead body <NUM> along an insertion direction D2 parallel to the axis A of the lead <NUM>. As a result, the retaining ring <NUM> is, along a radial direction R of the lead <NUM>, at least partially disposed between the annular electrode <NUM> and the sheath <NUM> covering the sleeve <NUM>. Furthermore, the shoulder <NUM> at the distal end <NUM> of the retaining ring <NUM> is disposed, along the longitudinal direction A of the lead, between the annular electrode <NUM> and the sleeve <NUM>.

<FIG>, which corresponds to <FIG>, depicts a subsequent method step in which electrically insulating adhesive <NUM>, in particular silicone adhesive, is introduced through the through-hole <NUM> (only visible in <FIG>) of the annular electrode <NUM>.

This insulating adhesive <NUM> is thus disposed in the residual space <NUM> between the inner wall <NUM> of the annular electrode <NUM>, the retaining ring <NUM> and the electrically insulating thermoformed sheath <NUM>.

In the following, the avoidance of chatter noise between the retractable fixation screw <NUM>, i.e. the helix electrode <NUM>, and the sleeve <NUM>, which constitutes a metallic distal housing portion of the lead, is explained with respect to the description of <FIG>.

<FIG> illustrates schematically an implantable pacing and/or defibrillation lead <NUM> according to a third example.

In the following, the implantable pacing and/or defibrillation lead <NUM> is also referred as "the lead <NUM>".

In particular, <FIG> shows a cross-sectional view parallel to a direction of extension D of the lead <NUM> of a portion <NUM> of the lead <NUM>. The direction of extension D of the lead <NUM> is parallel to a central longitudinal axis A of the lead <NUM>.

As the lead <NUM> in the first and the second examples, the lead <NUM> is provided with an elongated lead body 100A extending along the central longitudinal axis A from a proximal end (not represented in <FIG>) to a distal end <NUM>.

The proximal end (not represented in <FIG>) of the lead <NUM> is configured to be connected to an implantable medical device (not represented in <FIG>) in a manner known per se.

At least one coil conductor <NUM> extends from the proximal end of the lead <NUM> (said proximal end is not visible in the partial view of the lead <NUM> represented in <FIG>), through a lumen <NUM> of the lead <NUM>, toward the distal end <NUM> of the lead <NUM>. The coil conductor <NUM> is mechanically and electrically connected to a conductive driver shaft <NUM> moveably arranged along the central longitudinal axis A in a distal housing portion <NUM> of the lead <NUM>. Although it is not visible in the view of <FIG>, the coil conductor <NUM> is further mechanically and electrically connected to an implantable medical device at the proximal end of the lead <NUM>.

It is noted that the distal housing portion <NUM> is a distinct piece from the elongated lead body 100A.

As in the first and the second examples, a distal end <NUM> of the conductive driver shaft <NUM> is provided with an active fixation electrode <NUM>, in particular a helix electrode <NUM>. The active fixation electrode <NUM> is mechanically and electrically coupled to the conductive driver shaft <NUM> so as to form a retractable and extendable mechanism. Hence, the active fixation electrode <NUM> is movable along the central longitudinal axis A from a retracted position in which the active fixation electrode <NUM> is completely housed inside the distal housing portion <NUM>, to an extended position, as shown in <FIG>, in which the active fixation electrode <NUM> extends in a distal direction at least partially beyond the distal end <NUM> of the distal housing portion <NUM> of the lead <NUM>. The active fixation electrode <NUM> is electrically connected to the coil conductor <NUM> by means of the conductive driver shaft <NUM>.

As the sleeve <NUM> in the first and the second examples, in the third example the distal housing portion <NUM> of the lead <NUM> is provided with a cylindrical metallic body 122A of diameter L1. The use of metal, instead of plastic material, for the distal housing portion <NUM> allows reducing the dimension of the lead <NUM>, in particular the longitudinal dimension of the lead <NUM> as explained above in reference to <FIG>. Indeed, it allows advantageously radially superposing a ring electrode <NUM> (i.e. an annular electrode) provided around the elongated lead body 100A to the retractable and extendable mechanism formed by the conductive driver shaft <NUM> and the active fixation electrode <NUM> at the distal housing portion <NUM>.

The distal housing portion <NUM> is partially covered by an outer insulated sheath <NUM> preferably made of silicone rubber or polyurethane.

As in the second example, the ring electrode <NUM> according to the third example, i.e. the anode of the lead <NUM>, is not plastically deformed, e.g. by crimping.

Moreover, a retaining ring <NUM> is provided between the outer insulated sheath <NUM> and the ring electrode <NUM>. However, the retaining ring <NUM> according to the third example has a different shape and arrangement than the retaining ring <NUM> of the second example, in that a portion of the retaining ring <NUM> extends under the outer insulated sheath <NUM>.

An electrically insulated sheath <NUM>, in particular a heat-shrinkable sleeve <NUM>, more in particular a Teflon sheath <NUM>, is provided between the distal housing portion <NUM>, the outer insulated sheath <NUM>, the retaining ring <NUM> and the ring electrode <NUM> for electrically isolating the ring electrode <NUM> from the active fixation electrode <NUM>.

The lead <NUM> further comprises a guiding member <NUM> arranged inside the distal housing portion <NUM>. Views of the guiding member <NUM> are further shown in <FIG> to which reference is made in the following.

It is noted that the guiding member <NUM> is represented in <FIG> by the mouthpiece <NUM>. In fact, the mouthpiece <NUM> according to the first and second examples is the same as the guiding member <NUM> according to the third example.

Therefore, the description thereafter of the guiding member <NUM> also applies to the mouthpiece <NUM> according to the first and second examples.

The guiding member <NUM> comprises a tubular body <NUM> wherein a central lumen <NUM> of radius R0 extends therethrough from a distal end 138A to a proximal end 138B of the tubular body <NUM>. As shown in <FIG>, the conductive driver shaft <NUM> is slideably arranged through the lumen <NUM> of the tubular body <NUM>.

The tubular body <NUM> is electrically connected with the distal housing portion <NUM>, in particular by means of an annular shoulder member <NUM> comprising a first annular shoulder <NUM> of diameter L2 and a second annular shoulder <NUM> of diameter L3, as indicated in <FIG>. The first annular shoulder <NUM> and the second annular shoulder <NUM> extend radially from the tubular body <NUM>. The diameter L2 is greater than the diameter L3. As a result, a step <NUM> is formed between the first annular shoulder <NUM> and the second annular shoulder <NUM>. Moreover, the diameter L3 is substantially equal to the diameter L1 of the distal housing portion <NUM>. As shown in <FIG>, the tubular body <NUM> is thus adapted for receiving the distal housing portion <NUM> at the step <NUM> of the annular shoulder member <NUM>. The distal housing <NUM> thus abuts, along the central longitudinal axis A, on the first annular shoulder <NUM>, as shown in <FIG>. The tubular body <NUM> can be welded to the distal housing portion <NUM>, in particular at the step <NUM>, preferentially by laser welding. The laser weld allows providing long term mechanical strength and electrical continuity between the tubular body <NUM> and the distal housing portion <NUM>.

Between the annular shoulder member <NUM> and the proximal end 138B, the tubular body <NUM> comprises an elongated guiding portion <NUM>. As shown in <FIG>, the central lumen <NUM> at the elongated guiding portion <NUM> is adapted for partially receiving the conductive driver shaft <NUM> and the coil conductor <NUM>. The outer wall <NUM> of the elongated guiding portion <NUM> is provided with a plurality of annular grooves <NUM> (visible in <FIG>) for realizing a frictional fitting with a seal member <NUM> of the lead <NUM>, as shown in <FIG>. Hence, a mechanical connection is provided between the seal member <NUM> and the elongated guiding portion <NUM>.

As best shown in <FIG>, between the annular shoulder member <NUM> and the distal end 138A, the tubular body <NUM> comprises a radial opening <NUM> in communication with the lumen <NUM>. In the example of <FIG>, the radial opening <NUM> has an opening angle O of approximatively <NUM>° in a cross section of the tubular body <NUM> perpendicular to a direction of extension D of the lead <NUM>, which is indicated by the arrow D in <FIG>. In a variant, the opening angle O can be comprised between <NUM>° and <NUM>°, in particular between <NUM>° and <NUM>°. The radial opening <NUM> has a width L4 along the direction of extension D of the lead <NUM>.

As shown in <FIG>, the tubular body <NUM> has at least one chamfered edge <NUM> of length T1 at the radial opening <NUM>. The chamfered edge <NUM> extends along the direction of extension D of the lead <NUM>.

As illustrated in <FIG>, the radial opening <NUM> and the annular shoulder member <NUM> define a first portion <NUM> of the tubular body <NUM>. In the first portion <NUM>, at the radial opening <NUM>, the tubular body <NUM> has an outer radius R1, as indicated in <FIG>. As it can be understood from <FIG>, the outer radius R1 corresponds to the sum of the radius R0 of the lumen <NUM> and a lateral wall thickness of the tubular body <NUM>. It is noted that in <FIG>, the arrow indicated by "2xR1" shows the diameter of the tubular body <NUM>, which corresponds to two twice the radius R1.

The tubular body <NUM> comprises a second portion <NUM> extending from the distal end 138A of the tubular body <NUM> to the first portion <NUM>. The second portion <NUM> is provided with a groove <NUM> of width L5 along the direction of extension D of the lead <NUM>. The second portion <NUM> is provided with an external radially protruding shoulder <NUM> at the distal end 138A. An annular shoulder <NUM> is formed at the junction <NUM> between the first portion <NUM> and the second portion <NUM>.

As shown in <FIG>, a sealing means <NUM> is provided at the second portion <NUM> to seal the first portion <NUM> of the tubular body <NUM> from the distal end <NUM> of the lead <NUM>. The sealing means <NUM> is form-fitted to the second portion <NUM>, in particular by means of the groove <NUM> delimited between the external radially protruding shoulder <NUM> and the annular shoulder <NUM>. The sealing means <NUM> realizes a frictional fitting with the conductive driver shaft <NUM> and the distal housing portion <NUM>, as can be seen in the cross-sectional view of <FIG>. The sealing means <NUM> is further described in reference to <FIG>.

The lead <NUM> further comprises an electrically conductive compression spring <NUM>. The spring <NUM> is preferentially a closed monowire spring <NUM>, as illustrated in <FIG>. The spring <NUM> is thus a closed helical compression spring <NUM> comprising a plurality of coils 176A along its length.

In a variant, the spring <NUM> is an open spring comprising two free-ends, such as an open helical compression spring. In particular, the spring <NUM> can be a mono-wire (i.e. a single wire) open spring.

The spring <NUM>, when it is not arranged within the lead <NUM> as illustrated in <FIG>, has the following dimensions are indicated in the Table <NUM> below. It is understood that at the rest state of the spring <NUM>, the spring <NUM> is not assembled or mounted to any elements of the lead <NUM>. <FIG> represents the spring <NUM> at its rest state.

The inner radius d1 of the spring <NUM> at its rest state is less than the outer radius R1 of the first portion <NUM> of the tubular body <NUM> at the radial opening <NUM>.

The spring <NUM> is preferentially made of platinum iridium, which is a biocompatible material exhibiting satisfying resistance to corrosion adapted for the application of the implantable lead <NUM>. It is noted that the guiding member <NUM> is also preferentially made of platinum iridium, in particular for avoiding galvanic corrosion.

The spring <NUM> is at least partially radially arranged around the tubular body <NUM> and its radial opening <NUM>, such that the spring <NUM> is forced by its restoring force F against the conductive driver shaft <NUM>. As a result, the coils 176A that are partially deflected within the radial opening <NUM> provide multiple contact points with the conductive driver shaft <NUM>. Thereby, a continuous electrical contact between the active fixation electrode <NUM> and the distal housing portion <NUM> is realized by means of the spring <NUM>, which allows avoiding the occurrence of chatter noise.

As the coils 176A of the spring <NUM> only contact the conductive driver shaft <NUM> at the radial opening <NUM>, the additional friction generation caused by the coils 176A in contact with the conductive driver shaft <NUM> is negligible, in particular with respect to the quality of the deployment and the motion of the active fixation electrode <NUM>.

In the followings, a method for assembling the implantable pacing and/or defibrillation lead <NUM> according to the third example is described.

At a first step, the spring <NUM>, which is illustrated in <FIG>, is provided around the tubular body <NUM> of the lead <NUM> at the radial opening <NUM> such that a portion 176B (indicated by a circle 176B on <FIG>) of the spring <NUM> is partially deflected inside the lumen <NUM> due to its restoring force F. The restoring force F of the spring <NUM> corresponds to the force F, which acts to bring the spring <NUM>, in particular the portion 176B of the spring <NUM>, to its equilibrium position. The equilibrium position of the spring <NUM> is the position wherein its potential energy is minimum. As the spring <NUM> exerts radial forces, according to the principle of minimum potential energy for a spring, the 176B portion of the spring <NUM> enters, in particular is clipped to, the radial opening <NUM>, as shown in <FIG>, to reach a lower potential energy position.

In all variants of the present invention, the dimension of the opening angle O of the radial opening <NUM> is adapted to provide a sufficient opening for allowing a deflection of the spring <NUM> to a position of lower potential energy.

It is noted that, as indicated in <FIG>, the radial opening <NUM> has a width L4 along the direction of extension D of the lead <NUM> greater than the extension L6 of the spring <NUM> in the direction of extension D. It allows providing sufficient space for the deflection of the spring <NUM> towards a position of lower potential energy in the radial opening <NUM>.

In comparison with the lead known from the state of the art, the assembly is facilitated because the spring <NUM> can be simply slide and clipped to the tubular member <NUM> at the radial opening <NUM>, and thus does not require to be welded. Automated manufacturing is thus advantageously rendered possible.

The presence of the chamfered edges <NUM> allow avoiding damaging the spring <NUM> at the radial opening <NUM>.

Then, at a second step illustrated by <FIG>, the conductive driver shaft <NUM> is inserted via the distal end 138A through the lumen <NUM> of the conductive guiding member <NUM> thereby pushing at least partially the spring <NUM> outside the lumen <NUM> so as to provide an electrical connection between the spring <NUM>, in particular between the coils 176A of the portion 176B, and the conductive driver shaft <NUM>, as best shown in the cross-sectional view of <FIG>.

The plurality of coils 176A of the portion 176B of the spring <NUM> provide redundancy for the contacts to ensure a reliable connection. It is further noted that the ratio of the number of coils, or spirals, of the spring <NUM> with respect to the length of the wire forming the spring <NUM> is selected so as to provide sufficient deflection to the portion 176B combined with a low bearing force on the friction surface of the conduction shaft <NUM>. It therefore allows providing a limited parasitic friction torque.

At a third step, illustrated in <FIG>, the active fixation electrode <NUM> is mechanically and electrically connected by laser welding to the distal end <NUM> of the conductive driver shaft <NUM>. Moreover, the sealing means <NUM> is provided at the second portion <NUM> of the tubular body <NUM>. It is noted that the sealing means <NUM> is illustrated in transparency in <FIG>.

It is noted that, in an alternative, the active fixation electrode <NUM> can be mechanically and electrically connected by laser welding to the distal end <NUM> of the conductive driver shaft <NUM> before the insertion of the conductive driver shaft <NUM> in the lumen <NUM> of the conductive guiding member <NUM>.

In both alternatives, an assembly comprising the active fixation electrode <NUM>, the conductive driver shaft <NUM>, the sealing means <NUM>, the spring <NUM> and the conductive guiding member <NUM>, as illustrated in <FIG>, is obtained.

Then, the distal housing portion <NUM> is provided around the assembly illustrated in <FIG>. The distal housing portion <NUM> is mechanically and electrically connected to the tubular member <NUM> of the conductive guiding member <NUM> by laser welding. An electrically insulated sheath <NUM> can be heat-shrinked (i.e. heat-retracted) at least partially around the resulting assembly, as shown in <FIG>.

The resulting assembly of the conductive driver shaft <NUM>, the conductive guiding member <NUM> and the electrically conductive compression spring <NUM> is arranged at the distal end <NUM> of the lead <NUM> as shown in <FIG>.

<FIG> illustrates a fourth example of an implantable pacing and/or defibrillation lead <NUM>. Reference signs with the same tens unit than the reference signs already described and illustrated in <FIG> will not be described in detail again but reference is made to their description above, because they relate to same functional and/or structural elements.

As explained in reference to the third example, the continuous electrical contact between the active fixation electrode <NUM> and the distal housing portion <NUM> for preventing chatter noise is realized by means of the electrically conductive compression spring <NUM> being at least partially radially arranged around the tubular body <NUM> of the guiding member <NUM> and its radial opening <NUM>, such that the electrically conductive compression spring <NUM> is forced by its restoring force against the conductive driver shaft <NUM>.

In the third and the fourth examples, in the assembly state as illustrated in <FIG> and <FIG>, the radial opening <NUM>, <NUM> has a width L4 along the direction of extension D of the lead <NUM>, <NUM> greater than the extension L6 of the electrically conductive compression spring <NUM>, <NUM> in that direction. As already explained above, it allows providing sufficient space for the deflection of the spring <NUM>, <NUM> towards a position of lower potential energy in the radial opening <NUM>, <NUM>.

In the fourth example, the spring <NUM> is enclosed by an annular spring cover <NUM>, instead of the distal housing portion <NUM> (as in the third example).

However, in the assembly state, the inner diameter L1 of the distal housing portion <NUM> (shown in <FIG>), or of the annular spring cover <NUM>, is larger than the outer diameter D2 of the spring <NUM>, <NUM>. It is noted that the reference D2 refers to the outer diameter of the spring <NUM>, <NUM> in the assembly state, as illustrated in <FIG> and <FIG>, while the reference d2 refers to the outer radius of the non-assembled spring <NUM>, <NUM> in its rest state, as shown in <FIG>.

The electrical connection is thus not provided by a radial compression of the spring <NUM>, <NUM> toward the conductive driver shaft <NUM>, <NUM> applied by means of a recess or cage radially compressing the spring <NUM>, <NUM>, as in the lead known from the state of the art.

The purpose of the enclosure provided by the distal housing portion <NUM> to the spring <NUM> in the third example, or by the annular spring cover <NUM> to the spring <NUM> in the fourth example, is to protect the spring <NUM>, <NUM> from the external environment, in particular from damage like corrosion, or loss.

In <FIG>, a sealing means <NUM> is provided inside the distal housing portion <NUM> to seal an interface between the conductive driver shaft <NUM> and the distal housing portion <NUM>.

In the following, the sealing means <NUM> of the lead <NUM> according to the third example is further described in reference to <FIG>. The description herebelow related to the sealing means <NUM> also applies to the sealing means <NUM> of the lead <NUM> according to the first example and the second example (as shown in <FIG>).

As best shown in <FIG>, the sealing means <NUM> comprises a sealing ring 174A of central longitudinal axis B having at least two portions <NUM>, <NUM> disposed along the central longitudinal axis B of said sealing ring 174A.

The sealing means <NUM> is made of rubber, in particular of silicone, and is integrally formed in one-piece. The sealing means has a Shore hardness comprised between <NUM> to <NUM> Shore A.

<FIG> illustrates a cut-view perpendicular to the central longitudinal axis B of the sealing ring 174A. The central longitudinal axis B of the sealing ring 174A corresponds to the axis of revolution of the sealing ring 174A.

The sealing ring 174A has a lumen <NUM> defined by an inner wall <NUM> of the sealing ring 174A. The lumen <NUM> extends along the central longitudinal axis B from a distal end 182A to a proximal end 182B of the sealing ring 174A.

In the following, the expression "internal diameter" is to be understood as an inner diameter, i.e. a diameter of the lumen <NUM> defined by the inner wall <NUM>.

The first portion <NUM> of the sealing ring 174A has an internal diameter I1. The second portion <NUM> of the sealing ring 174A has an internal diameter I2.

The internal diameter I1 of the first portion <NUM> of the sealing ring 174A is less than the internal diameter I2 of the second portion <NUM> of the sealing ring 174A.

The lumen <NUM> of the sealing ring 174A is provided with an internal radial recess <NUM> of width W1 (along the central longitudinal axis B) at a junction <NUM> between the first portion <NUM> and the second portion <NUM> of the sealing ring 174A. At the junction <NUM>, the internal radial recess <NUM> has an internal diameter I3.

The internal diameter I2 of the second portion <NUM> of the sealing ring 174A is less than the internal diameter I3 of the internal radial recess <NUM> of the sealing ring 174A.

In the following, the expression "external diameter" is to be understood as an outer diameter of the sealing ring 174A.

The first portion <NUM> of the sealing ring 174A has an external diameter E1. The second portion <NUM> of the sealing ring 174A has an external diameter E2.

The external diameter E1 of the first portion <NUM> of the sealing ring 174A is less than the external diameter E2 of the second portion <NUM> of the sealing ring 174A. Hence, as shown in <FIG>, the first portion <NUM> and the second portion <NUM> are connected by a slope <NUM> at the junction <NUM>.

The inner wall <NUM> at the first portion <NUM> is provided with a rounded edge 186A at the distal end 182A. The inner wall <NUM> at the first portion <NUM> is further provided with a rounded edge 186B between the first portion <NUM> and the junction <NUM>.

The second portion <NUM> has a width W2 along the central longitudinal axis B.

<FIG> illustrates a cut-view perpendicular to the central longitudinal axis A of the lead <NUM>. In particular, <FIG> represents a partial view of <FIG>. Hence, the elements with the same numerical references used for the description in <FIG> refer to the same elements and will not be described again in detail.

The conductive driver shaft <NUM> comprises a shoulder <NUM> at its distal end <NUM>. The conductive driver shaft <NUM> further comprises an external radially protruding shoulder <NUM>. The external radially protruding shoulder <NUM> is longitudinally arranged between the active fixation electrode <NUM> and the sealing means <NUM>.

As already mentioned above with respect to <FIG>, the second portion <NUM> of the tubular body <NUM> of the guiding member <NUM> is provided with the groove <NUM> of width L5 along the central longitudinal axis A of the lead <NUM>. The width L5 of the groove <NUM> is substantially equal or greater than the width W2 of the second portion <NUM> of the sealing ring 174A. Hence, the second portion <NUM> of the sealing ring 174A can be received in the groove <NUM>. In particular, the second portion <NUM> of the sealing ring 174A can be maintained to the groove <NUM> of the guiding member <NUM> by a form-fit connection and/or a friction-fit connection.

The second portion <NUM> of the tubular body <NUM> of the guiding member <NUM> is further provided with the external radially protruding shoulder <NUM> at the distal end 138A of the tubular body <NUM>. The external radially protruding shoulder <NUM> is form-fitted into the internal radial recess <NUM> of width W1 of the sealing ring 174A.

As shown in <FIG>, the sealing means <NUM> is arranged around the conductive driver shaft <NUM> and the tubular body <NUM> for sealing the distal housing portion <NUM> from the distal end of the lead.

Indeed, the first portion <NUM> of the sealing ring 174A is arranged around, in particular directly arranged around (i.e. in surface contact with), the conductive driver shaft <NUM>. More precisely, the first portion <NUM> is longitudinally arranged between the external radially protruding shoulder <NUM> of conductive driver shaft <NUM> and the external radially protruding shoulder <NUM> at the distal end 138A of the tubular body <NUM>.

The section of the conductive driver shaft <NUM> passing through the lumen <NUM> of the sealing ring 174A at the first portion <NUM> of the sealing ring 174A has an external diameter E3.

The second portion <NUM> of the sealing ring 174B is arranged around, in particular directly arranged around (i.e. in surface contact with) the second portion <NUM> of the tubular body <NUM> of the guiding member <NUM>.

At the external radially protruding shoulder <NUM>, the tubular body <NUM> has an external diameter E4.

The end portion housing <NUM>, wherein at least the second portion <NUM> of the tubular body <NUM> and the conductive driver shaft <NUM> are received, has the internal diameter L1.

The first portion <NUM> of the sealing ring 174A has an external diameter E1 strictly less than the internal diameter L1 of the distal housing portion <NUM>.

In particular, the percentage difference of diameter between the external diameter E1 of the first portion <NUM> of the sealing ring 174A and the internal diameter L1 of the distal housing portion <NUM> is comprised between <NUM> % and <NUM>%, in particular between <NUM>% to <NUM>%.

The first portion <NUM> of the sealing ring 174A has an internal diameter I1 strictly less than the external diameter E3 of the conductive driver shaft <NUM>.

In particular, the percentage difference between the internal diameter I1 of the first portion <NUM> of the sealing ring 174A and an external diameter E3 of the conductive driver shaft <NUM> is comprised between <NUM>,<NUM> % and <NUM>%, in particular between <NUM>% and <NUM>%.

The above-mentioned range of percentage difference allows the conductive driver shaft <NUM> to rotate and slide with respect to the sealing ring 174A along the longitudinal axis A while preventing fluid communication at the interface between the conductive driver shaft <NUM> and the first portion <NUM> of the sealing ring 174A.

The second portion <NUM> of the sealing ring 174A has an external diameter E2 strictly more than the internal diameter L1 of the distal housing portion <NUM>.

In particular, the percentage difference between the external diameter E2 of the second portion <NUM> of the sealing ring 174A and the internal diameter L1 of the distal housing portion <NUM> can be comprised between <NUM> % and <NUM>%, in particular between <NUM>% and <NUM>%. In a preferred variant, the percentage difference between the external diameter E2 of the second portion <NUM> of the sealing ring 174A and the internal diameter L1 of the distal housing portion <NUM> is comprised between <NUM>,<NUM> % to <NUM>%, in particular between <NUM>% to <NUM>%.

Hence, the dimensions of the sealing ring 174A of the sealing means <NUM> allows avoiding fluidic communication from the distal end of the lead wherein blood can enter the distal housing portion <NUM>. It thus allows sealing the distal housing portion <NUM>, in particular wherein the electrically conductive spring <NUM> is housed for providing a continuous electrical connection. The sealing means <NUM> thus decrease the risk of surface and/or volume corrosion inside the distal housing portion <NUM>, in particular of the electrically conductive spring <NUM>.

The sealing means <NUM> is thus designed such that its first portion <NUM> comprises one constrain zone at the interface between the inner wall <NUM> and the conductive driver shaft whereas its second portion <NUM> comprises two constrain zones, respectively: at the interface between the inner wall <NUM> and the tubular body <NUM>, and, at the interface between the second portion <NUM> and the distal housing portion <NUM>.

Hence, in contrast with the second portion <NUM> of the sealing means <NUM>, there is no, or at least less, compressive forces exerted on the first portion <NUM> by the distal housing portion <NUM>. This is because there is no direct surface contact between the external wall of the first portion <NUM> of sealing means <NUM> and the distal housing portion <NUM>. Thereby, it allows reducing the friction applied by the sealing means <NUM> on the conductive driver shaft <NUM>. Indeed, the first portion <NUM>, in contrast with the second portion <NUM>, is not squeezed (i.e. compressed or elastically deformed) and maintained between two opposite surfaces. In fact, the second portion <NUM> of the sealing means <NUM> is compressed against the internal surface of the distal housing portion <NUM> and the external surface of the tubular body <NUM>.

In view of the above, the conductive driver shaft <NUM> can thus smoothly rotate and translate, even within the first portion <NUM>, so as to ensure a smooth deployment of the active fixation electrode without unwanted jerky motion of the conductive driver shaft <NUM> caused by friction.

It is noted that the internal diameter E3 of the first portion <NUM> of the sealing means <NUM> is configured to provide sealing properties at the interface between the inner wall <NUM> and the tubular body <NUM>. Hence, the sealing properties at the interface between the inner wall <NUM> and the tubular body <NUM> are ensured, despite any displacement of the conductive driver shaft <NUM> within the first portion <NUM> of the sealing means <NUM>.

Because the second portion <NUM> of the sealing means <NUM> is radially compressed between the internal surface of the distal housing portion <NUM> and the external surface of the tubular body <NUM>, the second portion <NUM> is maintained by form-fit and friction-fit connections between the distal housing portion <NUM> and the tubular body <NUM>. It allows holding the position of the sealing means while providing sufficient sealing properties.

It is noted that the Shore hardness of the sealing means <NUM> and the ratio of diameter differences can be advantageously selected in combination so as to provide appropriate sealing properties with minimum friction on the conductive driver shaft <NUM>.

It is further noted that the structural features of the sealing means <NUM> are not intrinsically linked to the presence or not of a radial opening <NUM> provided at the first portion <NUM> of the tubular body <NUM> of the guiding member <NUM>.

Claim 1:
An implantable pacing and/or defibrillation lead, comprising a lead body (<NUM>) provided with:
a proximal end configured to be connected to an implantable medical device, and
a distal end (<NUM>), opposite to the proximal end, the distal end (<NUM>) of the lead body (<NUM>) comprising an annular electrode (<NUM>) forming an anode (<NUM>) of said lead,
the lead further comprising a sleeve (<NUM>) into which an electrode (<NUM>) forming a cathode (<NUM>) of the lead is at least partially housed, in particular said electrode (<NUM>) is a retractable fixation screw (<NUM>),
wherein the sleeve (<NUM>) is partially accommodated in the distal end (<NUM>) of the lead body (<NUM>) such that the annular electrode (<NUM>) of the lead body (<NUM>) is superimposed to the sleeve (<NUM>),
characterized in that
the sleeve (<NUM>) is made of a metallic material, and
the sleeve (<NUM>) is electrically insulated from the annular electrode (<NUM>) of the lead body (<NUM>) by an electrically insulating Teflon sheath (<NUM>) heat shrunk on the sleeve (<NUM>).