Implantable medical lead

Abstract

The invention relates to an implantable medical lead, wherein the medical lead comprises an elongate body extending along a longitudinal direction between a distal tip and a proximal end and at least one electrode located at and / or in close proximity to the distal tip. To avoid dislocation of the medical lead and, at the same time, to avoid heart's wall contact, the elongate body comprises a spring-like section. The elongate body has a first inner lumen extending along the elongate body over the entire length of its spring-like section. The distal end of the spring-like section has a pre-defined distance from the distal tip of the elongate body. In the spring-like section the elongate body has a pre-formed loop-like or zigzag-like shape extending about and / or basically along the longitudinal direction in an operating state, wherein the spring-like section is configured to be straightened by a straight tool inserted into and extending through the first inner lumen in a transitional state. The invention further relates to a medical system comprising such implantable medical lead.

Description

[0001] Applicant: BIOTRONIK SE & Co. KG

[0002] Date: 18.112025

[0003] Our Reference: 24.125P-WO

[0004] Implantable Medical Lead

[0005] The invention generally relates to an implantable medical lead. Such medical lead usually comprises an elongate body extending along a longitudinal direction between a distal tip and a proximal end. Further, at least one electrode is located at and / or in close proximity to the distal tip. The invention further relates to a medical system comprising such implantable medical lead.

[0006] Medical leads implanted in a patient’s body for electrical cardioversion, pacing or defibrillation of the heart are generally known in the art. In particular, electrically transmissive leads may be implanted in or about the heart to reverse (i.e., defibrillate or cardiovert) certain life-threatening arrhythmias or to stimulate contraction (pacing) of the heart. Electrical energy is transmitted from a pulse generator which is electrically connected to the lead and its at least one electrode. Such transmitted electrical energy is applied to the heart via the at least one electrode of the medical lead to return the heart to normal rhythm or to stimulate the heart. Leads have also been used to sense conditions, materials or events (generally referred to as "sense" or "sensing") in the body, such as electrical potential in the atrium or ventricle of the heart. For that such medical lead may be connected to a sensing device using a connector at the proximal end of the medical lead. Alternatively, the sensed signals may be transmitted to and processed by the pulse generator, and, for example, used for pacing control.

[0007] Medical leads represent the electrical link between the pulse generator and the patient’s body tissue which is to be treated or sensed. Accordingly, the medical lead must be reliably mechanically and electrically connected to the patient’s body tissue at a pre-defined target location.

[0008] Most of the known artificial pacemakers and defibrillators are implanted as transvenous medical systems having intracardiac electrodes. For example, such pacemakers and defibrillators are mostly implanted in the left upper chest area, from where one or more leads are then guided through veins to the heart. The distal tip of the medical lead is usually anchored within the tissue of an inner heart wall (the heart’s muscle) to provide an electrical contact to the tissue and mechanical fixation at the target position.

[0009] Intracardiac leads used to treat arrhythmias such as bradycardia or tachycardia are usually placed in the ventricle with an excess length, also known as “slack”, of several centimeters. If the excess length (slack) is small, the respective lead tends to take on a more stretched shape in the heart, resulting in less wall contact. However, this increases the risk of dislocation as tensile forces can act on the fixation. If the excess length is too great, for example, more than 5 cm, the lead sags and forms a distinct sling such that there is the likelihood of frequent wall contact of this sling within the heart’s ventricle and thus the likelihood of undesirable ingrowth.

[0010] Tachycardia electrodes usually have a longer electrode (e.g. with a length greater than 4 cm) which is in the form of a helix and suitable for delivering high-voltage shocks. Regarding the efficiency of shock delivery, is advantageous to have a large electrode surface area to keep the surface current densities low. The thinner the lead, the longer the shock coil would have to be to maintain a large surface area. Accordingly, it is desired to place the shock electrode deep into the respective ventricle so that the entire electrode surface remains within this ventricle. A portion of the shock electrode that extends in the atrium contributes less to efficient shock delivery. However, this large surface area often is equivalent to a great slack having the above- mentioned disadvantages.

[0011] Accordingly, it is an object of the present invention to provide a medical lead that avoids dislocation and that, in case of a long shock electrode, ensures efficient shock delivery and, at the same time, avoids wall contact. The same object applies to the medical system.

[0012] The above object is solved by an implantable medical lead having the features of claim 1 and a medical system having the features of claim 13.

[0013] In particular, the above object is solved by an implantable medical lead, wherein the medical lead comprises an elongate body extending along a longitudinal direction between a distal tip and a proximal end and at least one electrode located at and / or in close proximity to the distal tip, wherein the elongate body comprises a spring-like section, wherein the elongate body has a first inner lumen extending along the elongate body over the entire length of its spring-like section, the distal end of the spring-like section has a pre-defined distance from the distal tip of the elongated body, wherein in the spring-like section the elongate body has a preformed loop-

[0014] 24.125P-WO / 18.11.2025 like or zigzag-like shape extending about and / or basically along the longitudinal direction in an operating state, wherein the spring-like section is configured to be straightened by a straight tool inserted into and extending through the first inner lumen in a transitional state. In close proximity to the distal tip means a maximum distance of 10 cm from the distal tip, in particular a maximum distance of 4 cm from the distal tip. The term ‘spring-like’ is intended to emphasize that the spring-like section (in the implanted state of the lead) should have a springy or force-absorbing effect. The term ‘spring-like’ does not mean that the spring-like section has to be shaped like a spring, screw or spiral, especially not before or during implantation.

[0015] The elongate lead body of the medical lead extends along a longitudinal direction from the proximal end of the implantable medical lead (in the following: lead) to the distal tip of the lead. In one embodiment, over most of its length, the longitudinal axis of the lead body corresponds to the longitudinal direction that extends from the proximal end to the distal tip of the implantable lead. At the distal tip a fixation assembly may be provided for mechanically anchoring the lead within the tissue of a patient’s heart to provide mechanical fixation at the target position. The fixation assembly may comprise a screw-like protruding fixation helix which may be screwed into the cardiac tissue for mechanical fixation. Further, the lead comprises at least one electrode at the distal tip or at a pre-defined distance (in longitudinal direction) from the distal tip. In one embodiment, the fixation helix may form one electrode. The at least one electrode is used in for electrical therapy like defibrillation or pacing and / or for electrical sensing of bodily parameters, in particular electrical parameters of the patient’s heart. For that, an electrical connector provided at the proximal end of the lead may be configured to be electrically and mechanically detachably or non-detachably connected with a pulse generator and / or a sensing device and / or data processing device (e.g. a cardiac monitor). Electrical signals from the pulse generator and / or the sensing device and / or data processing device may be transmitted via the lead to the at least one electrode and / or sensed electrical signals from the at least one electrode may be transmitted via the lead to the pulse generator and / or the sensing device and / or data processing device.

[0016] The lead may comprise just one electrode if the counter electrode is represented by a device different from the lead, e.g. the housing of the pulse generator or sensing device or an external electrode. If the counter electrode is realized at the lead, the lead may comprise at least two electrodes. The lead may comprise three electrodes and more than three electrodes, wherein at least one electrode may be provided for sensing.

[0017] 24.125P-WO / 18.11.2025 Further, the elongate body comprises a spring-like section. The distal end of the spring-like section has a pre-defined distance from the distal tip of the elongate body. This means that the spring-like section forms a section of the lead body having pre-defined length (in longitudinal direction), wherein this section does not include the distal tip of the elongate body but has a predefined distance from its distal tip and from the fixation assembly if the fixation assembly is provided at the distal tip. The distance of the distal end of the spring-like section from the distal tip of the lead body may be, for example, from 2 mm to 50 mm, in particular from 2 mm to 20 mm, in particular from 10 mm to 20 mm, or in other words, from 0.2 cm to 5 cm, in particular from 0.2 cm to 2 cm, in particular from 1 cm to 2 com. Additionally, the spring-like section has a first inner lumen extending along the elongate body over the entire length of its spring-like section. This inner lumen may extend from the spring-like section to the proximal end of the medical lead. It is an important feature of the lead that the spring-like section has a preformed loop-like or zigzag-like shape extending about or basically along the longitudinal direction in an operating state. This means that the whole lead body together with, if applicable, one or several electrodes located at the lead body surface takes the pre-formed loop-like or zigzag-like shape in its spring-like section in the operating state (e.g. after implantation within the patient’s heart), wherein the specific loop-like or zigzag-like shape is limited to the spring-like section. Accordingly, in the spring-like section the longitudinal axis of the body is different from the general longitudinal direction extending from the distal tip to the proximal end in the operating state due to the body’s loop-like or zigzag-like shape. Further, the spring-like section is configured to be flexible in the way that it can be straightened by a straight tool (e.g. a stylet or mandrel) inserted into and extending through the first inner lumen in a transitional state (e.g. temporarily during implantation). The first inner lumen may be a central or an off-centered inner lumen. In the straightened shape the lead can easily be implanted such that it is advanced within the patient’s body to the pre-defined target position within the patient’s heart and fixed there in a straightened condition. After the lead is correctly positioned, the straight tool may be removed from the inner lumen and the spring-like section returns to its operating state and, accordingly, to its preformed loop-like or zigzag-like shape. The loop-like or zigzag-like shape refer to a generally three-dimensional or two-dimensional loop-like structure as indicated below in detail. The preformed loop-like or zigzag-like shape absorbs tensile forces acting on the lead during normal use.

[0018] The preformed loop-like or zigzag-like shape may be provided by a removable heat-shrink tube that is applied to the outer surface of the spring-like section during manufacturing process and overmolding the spring-like section when laid in a mold. Alternatively, at least one elastic wire-

[0019] 24.125P-WO / 18.11.2025 shaped member having the pre-defined shape may be provided within and attached to at least one through-hole (inner lumen) of the insulating member or the insulating member of the lead body may comprise the pre-defined shape within the spring-like section. In a further alternative, a coil-shaped conductor of the medical lead may be deformed into the pre-defined shape and annealed. Further information regarding these manufacturing methods may be derived from below more detailed explanation.

[0020] In the operating state, i.e. during pacing, defibrillation and / or sensing, the spring-like section has a pre-defined shape that automatically provides an excess length avoiding dislocation of the lead. Accordingly, it is not necessary to build a slack during implantation, the required slack is achieved in a cost-efficient way. The pre-defined shape of the spring-like section additionally avoids frequent wall contact and therefore ingrowth as it prevents lead sagging while keeping the lead flexible for acting of tensile forces like a spring. The shape may also be adapted to the pre-defined usage of the lead and the patient’s anatomy within the respective ventricle of the heart. If the lead comprises a longer shock electrode at the spring-like section the lead realizes a continuous efficient shock delivery since the spring-like section provides a large surface area at a pre-defined distance from the heart’s tissue. This is realized by the particular shape of the spring-like section that is provided at a pre-defined distance from the distal tip of the elongate body. The shock impedance may be better predicted. Additionally, the design of the spring-like section saves energy because no shock energy is lost in an atrium of the patient’s heart. Further details and embodiments are explained below.

[0021] The elongate lead body may generally have a tubular structure with an outer member (cover) comprising electrically insulating material and mechanically protecting the at least one conductor accommodated within the electrically insulating material of the body. The internal lumen of the lead body accommodates at least one conductor, wherein each electrode is electrically connected to one terminal of the electrical connector assembly by one conductor formed by electrically conducting material. Each conductor may be formed, for example, by one electrically conducting wire, e.g. by a rope-shaped strand, by at least two braided or wound strands or by a helical strand. The design of each of the at least one conductor depends on the purpose of the lead. The conductor forms an inner member. For example, a conductor being a helical strand is used for high voltage application (e.g. defibrillation signals). Such conductor type is referred to as helical conductor. The electrically insulating material may be formed as an electrically insulating sleeve that fully surrounds the electrically conducting material of one conductor. Each one of the at least one conductor extends from the proximal end of the body to

[0022] 24.125P-WO / 18.11.2025 its distal end and is there electrically connected to the electrode material. An outer tubular insulating sleeve may be provided fully encompassing all conductors with the exception of the connection area of the electrical connector assembly at the proximal end of the lead and the area where the one or more electrode(s) are located at the distal end of the body.

[0023] In one embodiment, at least one electrode is located in the spring-like section. In particular, in one embodiment, one electrode located in the spring-like section is a shock electrode, for example formed as a helical electrode accommodated at the outer surface of the body within this spring-like section. As indicated above, such electrode realizes an efficient shock delivery because of the specific shape of the spring-like section, e.g. a loop-like shape. Additionally, this section and the shock electrode is provided with a pre-defined distance from the distal tip of the lead body and therefore from the heart’s tissue. The shock electrode may extend along the entire length of the spring-like section or may be shorter than the spring-like section, wherein, when it comes to the length, the specific shape of the electrode is not taken into account. It is just its extension along the body compared to the extension of the body in the spring-like section in the operating and transitional state.

[0024] In one embodiment, at least one electrode is located in a section of the medical lead located distally from the spring-like section. In one specific embodiment, at the spring-like section no electrode is provided. Accordingly, this spring-like section assures the absorption of tensile forces in the operating state of the lead. One electrode may be formed at the distal tip of the lead and / or one electrode may be provided within a pre-defined distance from the distal tip (e.g. a ring electrode), wherein the proximal end of such electrode has a distance different from zero from the distal end of the spring-like section.

[0025] In one embodiment, in the spring-like section the body having a loop-like shape extends in an inclined direction with regard to the longitudinal direction. In one embodiment, the loop-like shape is a helical shape or a polygonal loop shape, e.g. rectangular loop shape. Such helical or polygonal loop shape provides a three-dimensional form extending in a direction that is generally inclined with regard to the longitudinal direction, wherein the polygonal loop shape is basically similar to a helical loop shape but angular. With other words, this loop-like shape can also be described by the shape of a circular or angular ring, wherein the ring is cut through and the open ends of this cut ring have a pre-defined distance in longitudinal direction of the medical lead. The rectangular loop shape may also be compared with the shape of the Greek letter omega. The loop / ring / helix shape may define a radius that may extend perpendicular to the longitudinal

[0026] 24.125P-WO / 18.11.2025 direction. In one embodiment, the loop-like shape may comprise a loop / ring / helix from a 0.6 times one loop / ring / helix to a 4 / 3 times one loop / ring / helix, for example one full loop / ring / helix. In another embodiment, in the spring-like section the body having a zigzag-like shape extends generally in a plane containing the longitudinal direction. Such shape of the spring-like section is considered generally two-dimensional or provided within a small cuboid space having a thickness of, e.g., approximately the diameter of the elongate body. In this embodiment, the shape of the spring-like section is, for example, a sinusoidal shape or a zigzag shape, wherein the spring-like section may, e.g., contain a full period of a sinus or zigzag shape or more. Regarding all above shapes, a first (distal) portion of the spring-like section and the longitudinal direction may be at an angle from 20° to 90°, e.g. at an angle from 40° to 90°. The above shapes of the spring-like section provide the above explained mechanical properties, in particular the absorption of tensile forces. Regarding the efficient shock delivery, the above three-dimensional shapes (helical shape, polygonal loop shape) are the best suited. In one embodiment, the diameter of the loop-like shape is from 0.5 cm to 4 cm, for example from 1 cm to 3 cm, and / or the dimension of one period of the loop-like or zigzag-like shape in longitudinal direction is from 0.5 cm to 10 cm, for example from 2 cm to 8 cm, and / or the amplitude of the zigzag-like shape is from 0.5 cm to 5 cm, for example from 1 cm to 4 cm. In one embodiment, the first portion of the body at the distal end of the spring-like section and a second portion of the body at the proximal end of the spring-like section are configured such that they overlap along longitudinal direction and that their distance is from 0.5 cm to 10 cm, e.g. from 0.5 cm to 5 cm. The length of the spring-like section in the straightened state (i.e. in the transitional state) is, for example, from 30 mm to 100 mm, e.g. from 40 mm to 80 mm.

[0027] In one embodiment, the spring-like section comprises an inner, electrically insulating sleeve having a butterfly-like outer shape in cross-section. The butterfly-like outer shape comprises at least three notches, for example four or more than four notches, at the outer surface of the insulating sleeve extending parallel to or helical around the longitudinal direction. In one embodiment, these notches provide a lumen for accumulation of a plastic material that keeps a pre-defined shape of the spring-like section. Each notch may have a depth of, e.g., 0.1 mm to 0.2 mm in a radial direction (referring to the axis of the electrically insulating sleeve). The portions of the insulating sleeve between adjacent notches have a butterfly-wing-like shape. Each one of these portions provide sufficient space for an additional through-hole (second inner lumen) for guiding an additional conductor. Alternatively, an elastic element providing the shape of the spring-like section may be accommodated within one second inner lumen. Such elastic element may alternatively be accommodated within one notch at the outer surface of the electrically

[0028] 24.125P-WO / 18.11.2025 insulating sleeve forming the pre-defined shape of the spring-like section. In one embodiment, the spring-like section further comprises the at least one second inner lumen extending along the insulating sleeve over the entire length of the spring-like section and generally parallel to the first inner lumen. The at least one second inner lumen may extend along the lead body to the proximal end of the lead body. In one embodiment, one elastic element extending within one second inner lumen extends over the entire length of the spring-like section, as well.

[0029] The spring-like section may comprise two tubular and concentric electrically insulating sleeves, wherein the inner electrically insulating sleeve may electrically insulate an inner helical conductor from an outer helical conductor. The outer insulating sleeve (outer member) may form the outer surface of the spring-like section and electrically insulates the outer helical conductor from the environment.

[0030] The material of the insulating material of the outer member of the lead body may comprise or consist of at least one material of the group comprising Silicone, Polyurethane (PU). The electrically conducting material of the conductor may comprise or consist of at least one material of the group comprising stainless steel of the type MP35N (in the following short MP35N), Platinum, Titanium, Silver, Iridium and Thantal. The at least one electrode may comprise or consist of at least one material of the group comprising Platinum, Titanium, Silver, Iridium and Thantal. The elastic element providing the shape of the spring-like section may comprise or consist of at least one material of the group comprising Silicone, Polyimide (PI), Polyamide (PA), Polyether ether ketone (PEEK), Polyoxymethylene (POM) and Nickel titanium alloy (Nitinol).

[0031] The above object is further solved by a medical system comprising an implantable medical lead as described above and a pace generator and / or cardiac monitor, wherein the pace generator and / or cardiac monitor is configured to be mechanically and electrically connected to a connector of the medical lead. The pace generator may provide signals for pacing and / or defibrillation of the patient’s heart which are transmitted to the heart via the medical lead. The cardiac monitor and / or the pace generator may receive physiological signals from the patient’s body, e.g. from the heart, which may be used for pace control. The system realizes the same properties and advantages as the medical lead described above. It is therefore referred to above explanations provided for the medical lead.

[0032] 24.125P-WO / 18.11.2025 The present invention will now be described in further detail with reference to the accompanying schematic drawings, wherein

[0033] Fig. 1 shows a first embodiment of an implantable medical lead with pulse Generator and a first embodiment of the medical system within the patient’s body,

[0034] Fig. 2 depicts the embodiment of Fig. 1 within the patient’s heart,

[0035] Fig. 3 illustrates the embodiment of Fig. 1 with a stylet in a side view, wherein the body is partly transparent,

[0036] Fig. 4 shows the embodiment of Fig. 1 in a cross-sectional view,

[0037] Fig. 5 depicts a portion of the embodiment of Fig. 1 in longitudinal section,

[0038] Fig. 6 illustrates a second embodiment of an implantable medical lead in a cross- sectional view,

[0039] Fig. 7 shows a third embodiment of an implantable medical lead in a cross-sectional view,

[0040] Fig. 8 depicts a portion of the embodiment of Fig. 7 in longitudinal section,

[0041] Fig. 9 illustrates a fourth embodiment of an implantable medical lead in a cross- sectional view,

[0042] Fig. 10 depicts a portion of the embodiment of Fig. 9 in longitudinal section,

[0043] Fig. 11-12 illustrate a distal portion of the embodiment of Fig. 1 with a first shape of the spring-like section in a side view (Fig. 11) and in a front view (Fig. 12),

[0044] Fig. 13-14 depict a distal portion of the embodiment of Fig. 1 with a second shape in a side view (Fig. 13) and in a front view (Fig. 14),

[0045] 24.125P-WO / 18.11.2025 Fig. 15-16 illustrate a distal portion of the embodiment of Fig. 1 with a third shape in a side view (Fig. 15) and in a front view (Fig. 16),

[0046] Fig. 17-18 depict a distal portion of the embodiment of Fig. 1 with a fourth shape in a side view (Fig. 17) and in a front view (Fig. 18),

[0047] Fig. 19 shows a distal portion of the embodiment of Fig. 1 with a fifth shape in a front view,

[0048] Fig. 20-21 depict a distal portion of the embodiment of Fig. 1 with a sixth shape in a side view (Fig. 20) and in a front view (Fig. 21), and

[0049] Fig. 22 shows a distal portion of the embodiment of Fig. 1 with a seventh shape in a front view.

[0050] Fig. 1 to 5 and 11 to 12 show a first embodiment of an implantable medical lead 10 (in the following short: lead 10). The lead 10 comprises an elongate body 11 extending along a longitudinal direction, wherein the longitudinal axis of body 11 is indicated in Fig. 3 by dot- dashed line 13. The body 11 has a distal tip 15 and a proximal end 16. At the proximal end 16, the lead 10 comprises a (proximal) connector 17 configured to mechanically and electrically connect the lead 10 to a pulse generator 50 (e.g. an artificial pacemaker and / or defibrillator) or a cardiac monitor (not shown). At the distal tip 15 the lead 10 comprises a helical fixation member 18 protruding from the distal tip 15 which is configured to be screwed into the cardiac tissue at the target position. Within a pre-defined distance LI from the distal tip 15 (e.g. LI = 1 cm), the lead 10 comprises a ring electrode 19, for example a sensing electrode. The lead 10 further comprises a spring-like section 20 with a helical shock electrode (in the following also referred to as shock coil) 205 at the outer surface of the body 11. The distal end of the springlike section 20 has a distance L2 from the distal tip 15 of the lead body 11 of, e.g., L2 = 4 cm. The helical shock electrode 205 extends along the entire length L3 (e.g. L3 = 5 cm) of the springlike section 20 and has, therefore, the same length as the spring-like section 20. The lead 10 further comprises a central first lumen 106 having an inner diameter of 0.76 mm which extends along the entire length of the body 11 of the lead 10. Within the first lumen 106 the lead 10 comprises an inner helical conductor 101 consisting of, e.g., a bundle of four wires made of MP35N providing an electrical connection from a corresponding terminal of the proximal connector 17 to the helical fixation member 18. Accordingly, the helical fixation member 18

[0051] 24.125P-WO / 18.11.2025 functions as an additional electrode and provides, e.g., stimulation pulses to the heart’s tissue. The inner helical conductor 101 has, for example, an inner diameter of 0.45 mm and an outer diameter of 0.75 mm. The central first lumen 106 is formed by a tubular electrically insulating member 104, e.g. an insulating sleeve, extending along the entire length of the body 11 of the lead. The insulating member 104 has a butterfly-like shape at its outer surface comprising four notches (recesses) 102 extending parallel to the longitudinal axis of the insulating member 104. The notches 102 are filled with a biocompatible plastic material providing mechanical fixation of the helical shock electrode. The notches 102 are provided within the spring-like section 20, only. Outside the spring-like section the insulating member 104 does not have these notches and forms a cylindrical shell surface. As one can derive from Fig. 4, the insulating member 104 comprises four second lumens 108 extending parallel to the central first lumen 106 and along the entire length of the body 11 of the lead 10. Two of the second lumens 108 comprise each one rope-shaped second conductor 110 providing forward and return cable for the shock electrode 205. The rope-shaped conductor 110 has, e.g., an outer diameter of 0.35 mm.

[0052] As indicated in Fig. 1, 2, 11 and 12 in an operating state the spring-like section 20 has a looplike shape (see Fig. 11, 12) formed approximately section wise as a helical loop (central portion) with a deviation in the shape at the distal end and the proximal end portions of the spring-like section 20, the central portion comprising approximately 0.8 to 1.3 times one pitch of a helix. The distal and proximal end portions of the spring-like section 20 continue the direction of curvature of the central helical portion. Accordingly, in longitudinal direction the distal end portion and the proximal end portion of the spring-like section 20 overlap and have, e.g., a distance dl of 50 mm (see Fig. 12). The diameter DI of the loop is, for example, 20 mm.

[0053] Alternatively, in an operating state of another embodiment, as shown in Fig. 13 and 14 the spring-like section 20 may have a loop-like shape formed approximately sectionwise as a circular ring (central portion) with a deviation in the shape at the distal end portion and the proximal end portion of the spring-like section 20, the central portion comprising approximately 0.6 to 1.0 times one circular ring. The distal and proximal end portions of the spring-like section 20 do not continue the direction of curvature of the ring portion but have an opposite direction of the curvature of the ring portion. The dimension L4 of the spring-like section 20 in longitudinal direction is, for example, 50 mm.

[0054] Alternatively, in an operating state of another embodiment, as shown in Fig. 15 and 16 the spring-like section 20 may have a loop-like shape formed approximately sectionwise as a

[0055] 24.125P-WO / 18.11.2025 rectangular ring (central portion) with a deviation in the shape at the distal end portion and the proximal end portion of the spring-like section 20, the central portion comprising approximately 0.7 to 1.0 times one rectangular ring. The distal and proximal end portions of the spring-like section 20 do not continue the direction of the ring portion but have an opposite direction of the ring portion. The shape of the spring-like section may be compared with the shape of the Greek letter omega. The diameter D2 of the rectangular ring is, for example, 20 mm.

[0056] Alternatively, in an operating state of another embodiment, as shown in Fig. 17 and 18 the spring-like section 20 may have a zigzag-like shape formed approximately sectionwise as a sinusoidal shape (central portion) with a deviation in the shape at the distal end portion and the proximal end portion of the spring-like section 20, the central portion comprising approximately 0.9 to 1.2 times a sinusoidal shape. For example, one half period of such sinusoidal shape is 1 cm. The amplitude Al of the sinusoidal shape is, e.g., 1 cm. The dimension L5 of the spring-like section 20 in longitudinal direction is, for example, 2.2 mm. The distal and proximal end portions of the spring-like section 20 do not continue the sinusoidal shape but have a different curvature and direction. In particular, the distal end portion of the spring-like section 20 approximately continues within the plane of the sinusoidal central section. The shape of the spring-like section 20 of the embodiment shown in Fig. 19 is similar to the one of Fig. 17 and 18 except the shape of the distal end portion of the spring-like section 20. As one can derive from Fig. 19, the distal end portion of the spring-like section forms a loop extending laterally from the longitudinal direction.

[0057] Further alternatively, in an operating state of another embodiment, as shown in Fig. 20 and 21 the spring-like section 20 may have a zigzag-like shape formed approximately sectionwise as a zigzag shape (central portion) with a deviation in the shape at the distal end portion and the proximal end portion of the spring-like section 20, the central portion comprising approximately 0.9 to 1.2 times a zigzag. For example, one half period of such zigzag is 1 cm. The dimension L6 of the spring-like section 20 in longitudinal direction is, for example, 25 mm. The distal and proximal end portions of the spring-like section 20 do not continue the zigzag shape but have a different curvature and direction. In particular, the distal end portion of the spring-like section

[0058] 20 approximately continues within the plane of the zigzag central section. The shape of the spring-like section 20 of the embodiment shown in Fig. 22 is similar to the one of Fig. 20 and

[0059] 21 except the shape of the distal end portion of the spring-like section 20. As one can derive from Fig. 22, the distal end portion of the spring-like section forms a zigzag loop extending laterally from the longitudinal direction.

[0060] 24.125P-WO / 18.11.2025 As shown in Fig. 3, the specific shape of the spring-like section 20 may be straightened by, e.g. a stylet 40 in a transition state. The stylet 40 has, e.g. a diameter of 0.35 mm and consists of stainless steel or Tungsten. The stylet 40 is introduced from the proximal end 16 of the lead 10 into and extends along the first inner lumen 106 of the body 11 of the lead 10 and in particular along the spring-like section 20. In this transition state, the lead may easily be implanted and fixed with its fixation member 18 at a target position within the heart’s tissue of the patient. After implantation and fixation, the stylet 40 is removed from the lead 10 and the spring-like section 20 returns to its operating state with its particular shape shown in Fig. 1, 2 and 11 to 22. Then, the artificial pacemaker is implanted and electrically and mechanically connected to the lead 10 using the connector 17 in a known way. The pacing and / or defibrillation system comprising the lead 10 and the pacemaker / defibrillator 50 within the patient’s body 52 is shown in Fig. 1 and 2, wherein in Fig. 2 the accommodation of lead 10 within the right atrium (RA) and the right ventricle (RV) of the patient’s heart 54 is depicted in more detail.

[0061] As one can derive from Fig. 1, 2, 4, 5 and 11 to 22, in the operating state, i.e. during pacing or defibrillation, the spring-like section 20 has a specific shape that automatically provides an excess length avoiding dislocation and frequent wall contact and therefore ingrowth of the lead 10. The specific shape of the spring-like section 20 keeps the lead 10 flexible for acting of tensile forces. Further, the shock electrode 205 at the spring-like section 20 realizes a continuous efficient shock delivery since the spring-like section provides a large surface area at a predefined distance L2 from the heart’s tissue (see, e.g. Fig. 2 and 3). Accordingly, the shock impedance is better predictable. Additionally, the design of the spring-like section 20 saves energy because no shock energy is lost in the right atrium RA of the patient’s heart 54.

[0062] The specific shape of the spring-like section 20 of the lead 10 may be produced, for example, according to the following steps. After assembly of the shock coil 205 at the outer surface of the body 11, a heat-shrink tube consisting, e.g., of PU is placed over the shock coil 205. Then, the assembly with the heat-shrink tube is laid in a mold that corresponds to the pre-defined specific loop-like shape of the spring-like section 20 and shrunk onto the shock coil 205 in this specific form. The spring-like section 20 preformed in this way is then injected with Silicone which flows into the notches 102 and is vulcanized there. The heat-shrink tube prevents the Silicone mass from leaking through the shock coil 205 slots and is removed after vulcanization. This results in an elastically deformable spring-like section 20 that is pre-formed in the pre-defined shape in the operating state but can still be easily straightened using a stylet 40.

[0063] 24.125P-WO / 18.11.2025 In an alternative embodiment, an elastic, wire-shaped member 120 comprising the desired shape in the spring-like section 20 is placed within a notch 102 between the second inner lumens 108 (see Fig. 6). The elastic member 120 forces the spring-like section 20 into its pre-defined shape. If helical or circular structures are used as shown in Fig. 11 to 14, such wire-shaped member 120 may be cut from a wire of the desired diameter (e.g. 2 cm) having the specific shape and stretched straight. Then the member 120 may be paced in the notch 102 and overmolded or glued in place.

[0064] The elastic member 120 may also be obtained from an injection mold. The elastic member 120 may consist of Silicone, PI, PA, PEEK, POM or Nitinol. The member may consist of a thermoset or thermoplastic material whose glass transition temperature is well above body temperature (i.e. > 47°C).

[0065] In a further embodiment, the insulating member 104 itself is an injection-molded part that has been manufactured such that it has the specific shape in its spring-like section 20. Therefore, in this embodiment no additional element is needed for the provision of the shape.

[0066] In an alternative embodiment, the insulating member 104 consists of a thermoplastic material having the specific shape in the spring-like section 20, wherein the glass transition temperature of the material is well above body temperature (i.e. > 47°C).

[0067] Fig. 7 and 8 show another embodiment of an implantable medical lead 310 in a cross-section and in a longitudinal section of a portion of the body 311. This medical lead 310 does not comprise any electrode in its spring-like section. The body 311 comprises two tubular electrically insulating members 304 and 305. The inner electrically insulating member 304 is located concentrically within the outer electrically insulating member 305. The outer electrically insulating member 305 forms the outer surface of the lead 310 and protects its inner elements from the environment. The inner electrically insulating member 304 comprises a central first lumen 306 similar to the lead 10. An inner helical (coil-shaped) first conductor 301 consisting of, e.g., a bundle of four wires made of MP35N provides an electrical connection from a corresponding terminal of the proximal connector to an electrode. The lead body 311 further comprises a helical (coil-shaped) second conductor 303 consisting of, e.g. a bundle of four wires made of MP35N providing an electrical connection from a corresponding terminal of the proximal connector to the electrode. The second conductor 303 is accommodated between the inner insulating member 304 and the outer insulating member 305. The first conductor 301 and

[0068] 24.125P-WO / 18.11.2025 the second conductor 303 may form the forward and return cable for one stimulation electrode, e.g. a ring electrode, provided at the distal tip portion of the body 311. However, as indicated above, this electrode is not located within the spring-like section but has a pre-defined distance from the distal end of the spring-like section of, e.g., 2 mm.

[0069] A further embodiment of an implantable medical lead 410 is depicted in Fig. 9 and 10 in a crosssection and in a longitudinal section of a portion of the body 411. This medical lead 410 does not comprise any electrode in its spring-like section, either. The body 411 comprises one tubular electrically insulating member 405. The outer electrically insulating member 405 forms the outer surface of the lead 410 and protects its inner elements from the environment. The outer electrically insulating member 405 comprises a central first lumen 406 similar to the lead 10. An inner helical (coil-shaped) first conductor 401 consisting of, e.g. a bundle of four wires made of MP35N provides an electrical connection from a corresponding terminal of the proximal connector. The first conductor 401 electrically connects one stimulation or sensing electrode, e.g. a ring electrode, provided at the distal tip portion of the body 411 and is accommodated within the outer insulating member 405. However, as indicated above, the electrode is not located within the spring-like section but has a pre-defined distance from the distal end of the springlike section of, e.g., 2 mm.

[0070] Both embodiments shown in Fig. 7 to 10 are similar to the first embodiment shown in Fig. 1 to 5 and 11 to 22 with regard to their other elements. In particular, these embodiments comprise a spring-like section, wherein the distal end of the spring-like section has a pre-defined distance of 10mm from the distal tip of their body 311, 411. These embodiments further may comprise any shape of their body 311, 411 in the spring-like section that is depicted and explained in connection with Fig. 11 to 22.

[0071] This specific shape may be manufactured by deforming the MP35N first coil-shaped conductor 301, 401 into the pre-defined shape in the spring-like section and annealed (e.g. at a temperature greater than 1000°C) and suitably cooled down. As a result of the heating and cooling process, the coil structure of the conductor 301, 401 takes on the pre-defined shape. Additionally, the rigidity of the first conductor increases in this spring-like section, thus forming an elastic looplike or zigzag-like shape that can be straightened by a stylet. These manufacturing method steps for providing the specific shape of the spring-like section can be used for electrode leads for the treatment of bradycardia without a shock coil. In this case, the spring-like section absorbs tensile forces provided, for example, by the heart’s activity.

[0072] 24.125P-WO / 18.11.2025

Claims

Claims1. An implantable medical lead (10, 310, 410), wherein the medical lead (10, 310, 410) comprises an elongate body (11, 311, 411) extending along a longitudinal direction between a distal tip (15) and a proximal end (16) and at least one electrode (205) located at and / or in close proximity to the distal tip (15), wherein the elongate body (11, 311, 411) comprises a spring-like section (20), wherein the elongate body (11, 311, 411) has a first inner lumen (106, 306, 406) extending along the elongate body (11, 311, 411) over the entire length (L3) of its spring-like section (20), wherein the distal end of the spring-like section (20) has a pre-defined distance (L2) from the distal tip (15) of the elongate body (11, 311, 411), wherein in the spring-like section (20) the elongate body (11, 311, 411) has a preformed loop-like or zigzag-like shape extending about and / or basically along the longitudinal direction in an operating state, wherein the spring-like section (20) is configured to be straightened by a straight tool (40) inserted into and extending through the first inner lumen (106, 306, 406) in a transitional state.

2. The medical lead (10, 310, 410) according to claim 1, wherein at least one electrode (205) is located in the spring-like section (20).

3. The medical lead (10, 310, 410) according to claim 2, wherein one electrode (205) located in the spring-like section (20) is a shock electrode.

4. The medical lead (10) according to claim 1, wherein at least one electrode (19) is located in a section of the medical lead (10) located distally from the spring-like section (20).

5. The medical lead (310, 410) according to claim 4, wherein no electrode is located in the spring-like section.

6. The medical lead (10, 310, 410) according to any one of the previous claims, wherein in the spring-like section (20) the body (11) having a loop-like shape extends in an inclined direction with regard to the longitudinal direction or wherein in the spring-like section (20) the body (11) having a zigzag-like shape extends generally in a plane containing the longitudinal direction.24.125P-WO / 18.11.20257. The medical lead (10, 310, 410) according to any one of the previous claims, wherein the distance (L2) of the distal end of the spring-like section (20) from the distal tip (15) of the elongate body (11) is from 0.2 cm to 2 cm and / or wherein the diameter (DI, D2) of the loop-like shape is from 0.5 cm to 4 cm and / or the dimension (L4, L5, L6) of the loop-like or zigzag-like shape in longitudinal direction is from 0.5 cm to 10 cm and / or the amplitude (Al) of the zigzag-like shape is from 0.5 cm to 5 cm.

8. The medical lead (10, 310, 410) according to any one of the previous claims, wherein a first portion of the body (11) at the distal end of the spring-like section (20) and a second portion of the body (11) at the proximal end of the spring-like section (20) are configured such that they overlap along longitudinal direction and that their distance (dl) is from 0.5 cm to 10 cm.

9. The medical lead (10, 310, 410) according to any one of the previous claims, wherein the loop-like shape is a helical shape or a polygonal loop shape or the zigzag-like shape is a sinusoidal shape or a zigzag shape.

10. The medical lead (10, 310, 410) according to any one of the previous claims, wherein the spring-like section (20) comprises an inner, electrically insulating sleeve (104) having a butterfly-like outer shape in cross-section.

11. The medical lead (10, 310, 410) according to any one of the previous claims, wherein the spring-like section (20) further comprises at least one second inner lumen (108) extending along an insulating sleeve (104) over the entire length of the spring-like section (20) and generally parallel to the first inner lumen (106).

12. The medical lead (10) according to any one of the previous claims, wherein the springlike section (20) comprises at least one helical conductor (101).

13. A medical system comprising a medical lead (10) according to any one of the previous claims and a pace generator (50) and / or cardiac monitor, wherein the pace generator (50) and / or cardiac monitor is configured to be mechanically and electrically connected to a connector assembly (17) of the medical lead (10).24.125P-WO / 18.11.2025

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