WO2022063511A1

WO2022063511A1 - Intra-cardiac device

Info

Publication number: WO2022063511A1
Application number: PCT/EP2021/073481
Authority: WO
Inventors: Sebastian Klaus; Martin Henschel; Devan Hughes; Dirk Muessig; Volker Lang
Original assignee: Biotronik Se & Co. Kg
Priority date: 2020-09-23
Filing date: 2021-08-25
Publication date: 2022-03-31

Abstract

The invention refers to an intra-cardiac device for fixation at an anchoring region within the tissue of a patient's heart, wherein the intra-cardiac device comprises one electrode (24) attached at its distal end and a housing (20) having a longitudinal axis (28), wherein the intra-cardiac device comprises a fixation assembly attached at the distal end of the housing (20) and encircling at least part the housing (20) along its longitudinal axis (28), wherein in a deployed state the fixation assembly comprises one first circular element (31) and at least one second circular element (32) located proximal from the first circular element (31), wherein the first circular element (31) and the at least one second circular element (32) are mechanically connected and the first circular element (31) has a smaller diameter than an adjacent one of the at least one second circular element (32).

Description

INTRA-CARDIAC DEVICE

The present invention refers to an implantable intra-cardiac device, such as an implantable intra-cardiac pacemaker.

Active or passive intracardiac devices, for example implantable intra-cardiac pacemakers (also known as leadless pacemakers), are well known miniaturized medical devices, which are entirely implanted into the cardiac ventricle or atrium of a patient. Intracardiac pacemakers are used for patients who suffer from a bradycardia. Intracardiac devices apply electrical stimulation in the form of pulses to the heart in order to generate a physiologically appropriate heartrate (intracardiac pacemakers) and/or in the form of shocks for cardioversion or defibrillation in order to restore a more normal heart rhythm. Alternative or additional functions of intracardiac devices comprise providing other electrical or electromagnetic signals to the heart or its surrounding tissue and sensing electrical or electromagnetic signals or other physiological parameters of the heart and/or its surrounding tissue.

Intracardiac device fixation mechanisms are currently only used for ventricular implantation. As intracardiac pacemakers use is expanded to dual-chamber applications, specialized atrial fixation methods are also needed. Atrial anatomy dictates safe and reliable fixation approaches. The right atrium lateral wall and appendage is extremely thin and sparsely covered with pectinate muscle. In contrast, the septal and posterior right atrium walls are smooth without any pectinate muscles. Given the differences in tissue properties between the ventricle and the atrium, such as thickness and elasticity, known solutions that are intended for ventricular location would not provide safe and reliable tissue contact for the atrial application. Document US 8,700,181 B2 discloses an intracardiac medical device for implantation comprising electrodes formed as fixing mechanism similar to a pair of large diameter double helices similar to screws with a positive deflection near a base at the distal end of the device. For fixation the double helices are screwed into the heart's wall. The purpose of this shape is to ease implantation of the device but render unscrewing the device very difficult due to its firm adhering to the wall. Further, the distal ends of the double helices may have serrated edges that prevent the device from unscrewing out of the heart's chamber wall. Such fixation mechanism seems not applicable to the thin atrial walls. Another embodiment of an intracardiac medical device for implantation into one atrium discussed in this document comprises a stabilizing intra-cardiac device extension connected to the housing. The stabilizing extension includes a stabilizer arm and/or an appendage arm or an elongated body or loop member configured to be passively secured within the heart. The stabilizing extension is located at the end of the intra-cardiac device opposite the electrode. The appendage arm includes a distal end upon which an electrode is located. The electrode is a passive electrode that is configured to simply rest against a selected activation site or an active fixation electrode that is configured to be secured to the tissue at the activation site. Further, the stabilizer arm has a distal end that is positioned in the superior vena cava (SVC), wherein the stabilizer arm extends across the whole right atrium. In this position, the stabilizer arm applies a quite high force to the SVC wall leading to an increased risk of injury of the thin tissue of the heart and the vein in this region.

Document US 2004/0147973 Al discloses an intracardiac pulse generator for implantation into a cardiac chamber or a portion of the cardiac chamber such as the left atrial appendage. The pacemaker comprises a hermetically sealed housing and a shield which is resilient and expands in its deployed state to conform to the shape of the anatomic structure that is used to retain the intra cardiac pulse generator, e.g. the right atrial appendage.

An implantable medical device is described in US 2018/0126179 Al having a housing and expandable and elongated anchoring members extending from the housing, wherein the housing extends from the first end of the expandable anchoring members towards the second end of the expandable anchoring members. Further, the first end of the housing extends past ends of the expandable anchoring member. The device is deployed and positioned such that the cathode electrode of the housing engages the heart wall to sense signals from the heart and/or applies pace signals to the heart.

Accordingly, there is the need for implantable intracardiac devices for atrial use having a fixation mechanism / anchoring method that would provide stable positioning of the device without damaging the sensitive myocardial tissue, simple implantation and low manufacturing effort and costs.

The above problem is solved by an intracardiac medical device as defined in claim 1.

In particular, the intracardiac device of the invention, particularly an intracardiac pacemaker, for fixing at an anchoring region within the tissue of a patient's heart, particularly an atrium or an atrial appendage comprises one electrode attached at its distal end and a housing having a longitudinal axis. Further, the intracardiac device comprises a fixing assembly attached at the distal end of the housing and encircling at least part the housing along its longitudinal axis, wherein in a deployed state the fixation assembly comprises one first circular element and at least one second circular element located proximal from the first circular element, wherein the first circular element and the at least one second circular element are mechanically connected and the first circular element has a smaller diameter than an adj acent one of the at least one second circular element. Furthermore, the intracardiac device of the invention, in particular the fixation assembly has a collapsed state for delivery in addition to the above mentioned deployed state.

The first circular element and the at least one second circular element may be formed by a wire or filament, wherein the wire or filament may have a circular, elliptical or angular (e.g. rectangular or square) cross section. There may be one first circular element and one second circular element but also two or more second circular elements.

One circular element may be formed as a ring, i.e. a closed structure, but also as an open structure such as an incomplete ring, helix or spiral, wherein the spiral may be formed in one plane or spatially. One circular element comprises at least 75 % of the circumference of a full circle or encircles at least 270 degrees. The diameters of the first circular element and the at least one second circular element may be adapted to the anatomical conditions at and around the anchoring region. The diameter of the first circular element is smaller than the diameter of the adjacent one of the at least one second circular element, wherein the diameter is an inner diameter of the circular structure. If there are two or more second circular elements, the circular element which is not the adjacent one to the first circular element may have the same diameter, a greater diameter or a smaller diameter as/than the second circular element which is the adjacent one to the first circular element. The diameters of the first circular element and the at least one second circular element are greater than the outer diameter of the housing of the intra-cardiac device at the respective position of the respective circular element along the longitudinal axis of the housing, because the circular elements encircle or surround the housing and fix the intracardiac device at the anchoring region as indicated above. Further, the fixation assembly assures that there is a reliable mechanical and electrical connection of the electrode at the distal end of the housing to the tissue at the anchoring region. Non limiting examples for suitable diameters of the first circular element and/or the at least second circular elements include diameters in the range of larger than 7 mm to not more than 40 mm.

The above intracardiac device is especially suitable to be fixed in an atrial appendage. An implant located there does not interfere significantly with the blood flow to the respective ventricle. Also, it has been shown that closing off the appendage (mostly left atrial site) is a safe and effective procedure in patients with permanent atrial fibrillation. The atrial appendage may be the right atrial appendage or the left atrial appendage. Preferably, the intra-cardiac device is particularly configured to pace and/or sense in the right atrium, particularly to optimize sensing the beginning of the cardiac cycle from the sinus node. The device is positioned such that the distal tip of the device is located in the back end or rearward end of the appendage. There, the fixation assembly distributes the pressure to the atrial myocardium as much as possible in order to provide stable positioning of the device without damaging the myocardial tissue. In particular, the pressure distribution is provided by the first circular element and the at least one second circular element, which are supported by the tissue in the anchoring region surrounding the intra-cardiac device. In addition, specific fixing elements on the fixation assembly may be employed to prevent slipping out of the wedged position (see below).

The above defined implantable intracardiac medical device, for example a leadless pacemaker, may comprise a cylindrical housing or a housing having the form of a truncated cone having the above mentioned longitudinal axis and the electrode projecting from the distal end of the housing, wherein the electrode may extend into the direction of the longitudinal axis. Preferably, the electrode is formed by a feedthrough pin extending through and being insulated from the housing, and an electrode tip, which is preferably fractally coated. Further, a header assembly may be arranged at and attached to the distal end of the housing of the intracardiac device such that the electrode projects through the header assembly, i.e. a respective through-going or complete opening of the header assembly. The opening may be a central opening. The cylindrical housing comprises the electronics module having a processor, an energy source (e.g. a battery or coil (for wireless charging)) and, if applicable, a communication component such as an antenna. The processor may comprise a storage unit for data storage. The processor may be adapted to process signals determined from the patient's body or received from the surrounding environment and/or to produce signals for treatment of the patient's heart. Such signals may comprise electrical stimulation in the form of pulses in order to generate a physiologically appropriate heartrate, shocks for cardioversion or defibrillation in order to restore a more normal heart rhythm and/or other electrical or electromagnetic signals to the heart or its surrounding tissue. Such signals are transformed and transmitted by the electronics module and may be applied by the electrode to the heart or its surrounding tissue. The electrode is electrically connected to the electronics module and the energy source. The electrode may be designed in form of a pin. The electrode may be formed by a feedthrough pin of the device an electrode tip, which preferably comprises a fractal coating. The hermetically sealed housing may comprise biocompatible material and/or electrically conducting material, e.g. titanium, and may function as another electrode. In one embodiment, at the distal end of the intra-cardiac device the electrode is located at a central position, preferably at the longitudinal axis of the intracardiac device.

In one embodiment, the intra-cardiac device comprises a fixation assembly, wherein the first circular element is one first ring and the at least one second circular element is at least one second ring, wherein the first ring and the at least one second ring are mechanically connected by at least two spokes projecting inclined from the outer surface of the housing or with regard the longitudinal axis in the deployed state. The at least two spokes may run straight or slightly curved and may be equally spaced or offset around the circumference of the housing. The fixation assembly of this embodiment forms an umbrella like structure and comprises the at least two spokes attached at the distal end of the housing, e.g. by an assembly with header components of an insulating material. Those spokes provide a “frame” connecting to the ring structure containing the one first ring and the at least two second rings, oriented in a circular fashion. This frame may be fabricated by joining separate rings and spokes together, or by cutting a single piece including from a tube and shape setting the cylinder to achieve the desired shape. One spoke may be shorter than the length of the housing in the direction of the longitudinal axis. One spoke may be formed as a strut or strip having a radial or angular (e.g. rectangular) cross section. The number of spokes and rings are variable and may be adapted to the individual condition of the patient, for example 5 spokes, one first ring and two second rings can be used. Alternatively, for example, a different number of spokes ranging from 3 to 7 and a different number of rings, ranging from 2 to 5 is possible. The length of each spoke may be, for example, in the range of 5 mm to 25 mm In one embodiment, the length of each stroke is less than the length of the housing in its longitudinal direction.

The first ring and the at least one second ring may contain additional mechanism that allow the ring to collapse when the fixation assembly is pushed against the intracardiac device. Such mechanism may be generated e.g. by different stiffness of the material or preformed “kinks”. Accordingly, in one embodiment, each of the first ring and the at least one second ring forms a slacked ring in the collapsed state. In the collapsed state the at least two spokes may abut the shell surface of the housing over a major part of their length and/or may run parallel to the longitudinal axis of the housing.

Particularly, in case of the first and the at least one second ring comprises preformed kinks as described in the preceding paragraph, such kink is preferably arranged substantially in the middle of a ring section that is delimited by two adjacent spokes, thereby dividing the ring section in substantially equal parts thereof. In one embodiment, the intracardiac device comprises a fixation assembly, wherein the first circular element and the at least one second circular element together form a conical spiral comprising at least 1.5 turns, this means that the first circular element forms a distal at least 0.75 turn and the at least one second circular element forms a proximal at least 0.75 turn of the conical spiral. The first circular element and the at least one second circular element are mechanically connected by the conical spiral itself, i.e. the circular elements are directly connected at their ends. The conical spiral starts with a smaller diameter close to the distal end of the intra-cardiac device and constantly increases the diameter as one moves proximally along the fixation assembly. Such embodiment would allow, using a rotational movement, placement of the pacing electrode as close as possible to the myocardium. The conical spiral is supported over the major part of its length or the full length at the tissue at the anchoring region and thereby provides distribution of the forces for fixing of the intracardiac device at the heart's atrial tissue over a large area.

In one embodiment, the fixation assembly is a component separate from the housing and comprises an additional ring at its distal end, wherein the ring has an inner diameter slightly smaller than the outer diameter of the housing at its distal end, wherein the additional ring is removably attached to the distal end of the housing of the intracardiac device. In this embodiment, the fixation assembly may be loosely attached to the intracardiac device. This can be achieved by generation of a hole in the front middle section of the fixation assembly formed by the additional ring in which the intra-cardiac device may be positioned. Loosely attaching may be achieved by having a flexible (stretchable) round additional ring (O-ring). To ensure secure connection of the intra-cardiac device to the fixation, assembly the device may have a circular groove or indentation with a diameter at the bottom of the groove being equal to the inner diameter of the O-ring. In this embodiment, the housing comprises at least one annular groove at its shell surface for accommodation of the ring. In this embodiment, the housing at this region of attachment may be coated with an electrically isolating coating such that the fixation mechanism is not electrically connected to the device housing. Alternately, the fixation mechanism may be attached with an adaptor made from an electrically isolating material, such as, for example, PEEK, e.g. the above mentioned header assembly. In one embodiment, the fixation assembly comprises a plurality of fixation elements such as fingers, tines, barbs, hooks, half-spheres, or elements having similar shape projecting radially outwards from at least one of the circular elements, either the first circular element and/or the at least one second circular element and/or from the at least two spokes. The plurality of tines, barbs, fingers or hooks are provided to avoid slipping out of the wedged position forming additional fixing elements as part of the main frame formed by the fixation assembly. For that, the tines, barbs, fingers or hooks may project radially outwards along their entire length or over part of their length in the deployed state of the fixation assembly. Such additional fixing elements may be connected at the crossings of the spokes and the first ring or the at least one second ring. These may be attached by joining processes such as welding or crimping. The additional fixation mechanism may have the appearance of barbs or flukes. Such additional fixation elements may not be formed pointy or sharp to prevent tissue damage.

In an embodiment, the fixation assembly may have a surface structure comprising a plurality of round or angular indentations (dimples) being disposed adjacent to one another at its outer surface (in particular the outer surface forming the outer shell surface) in order to avoid movement of the fixation assembly (and thereby of the intra-cardiac device) with regard to the tissue after deployment at the anchoring region. The surface structure may cover a part of or the full outer shell surface.

In one embodiment, the intracardiac device of the invention further comprises a membrane or fabric supported by or attached to the fixation assembly, particularly the first circular element, the at least one second circular element and/or the at least two spokes. The membrane of the fabric may a textile structure like e.g. non-woven/ fleece-like (e.g. made by electro-spinning). The membrane or fabric may be made of suitable biocompatible polymers, e.g. polyurethanes or PET. Alternatively the membrane may be made of porous ePTFE-membranes. As another alternative, the membrane or fabric may be made of bioresorbable material, such as, for example, PLGA or PLLA. Additionally or alternatively, the membrane or the fabric may be coated with material(s) or substance(s) that improve the biocompatibility and/or enhance cellular or protein adhesion and/or promotes coagulation/thrombogenization. Suitable materials or substances include, without being restricted to, heparin.

In one embodiment, the fixation assembly comprises or is substantially made of a biocompatible material(s), for example a metal (e.g. a shape memory material such as Nitinol) or a polymer material (e.g. PEEK),. Alternatively, only parts (e.g. the rings) of the fixing may be made of such material.

In one embodiment, the intra-cardiac device further comprises a hitch at the proximal end of the housing. The hitch is used to deploy and retrieve the intracardiac device. In this embodiment, the hitch has a neck with a diameter smaller than the outer diameter of the device housing. This neck expands into a “T-shaped” profile with a channel to accommodate a tether within the implantation tool so that a catheter structure may secure and interact with the intra-cardiac device during release and resheathing. For example, the catheter may push and pull the hitch in and out of the catheter. Once released, the “T-shape” allows for a snare of a retrieval catheter to recapture the device if a removal is required.

The present invention will now be described in further detail with reference to the accompanying schematic drawing, wherein

Fig. 1 shows a first embodiment of the inventive intra-cardiac device in a side view in deployed state,

Fig. 2 depicts the embodiment shown in Fig. 1 in its collapsed state.

Fig. 1 illustrates a first embodiment of an implantable intra-cardiac device, e.g. a leadless pacemaker, in a deployed state after fixing of the device at an anchoring position within the heart's tissue of a patient, e.g. the right atrial appendage (not shown).

The intra-cardiac device comprises a cylindrical housing 20. A header 22 and a tip electrode 24 are located at the distal end of the housing 20. The electrode 24 protrudes through the header 22 and from its distal end face. The cylindrical housing 20 has a longitudinal axis 28, which axis also forms the axis of the electrode 24. At the proximal end of the housing 20, the intra-cardiac device comprises a hitch 29 for deployment and retrieval. The tip electrode 24 is preferably formed by a feedthrough pin extending through and electrically insulated from the housing and an electrode tip, wherein the electrode tip is preferably fractally coated. Preferably, the feedthrough pin and the electrode tip are joined by welding.

The housing 20 of the intra-cardiac device contains a battery and an electronic module comprising a processor and ensures hermetically sealing of these components. These components are electrically connected to the electrode 24 and provide the electrical stimulation of the heart or processing of electrical signals determined from the heart. Further, the housing 20 may contain components for communication such as an antenna.

The intra-cardiac device comprises a fixation assembly having a first circular element formed as a first ring 31 and two circular elements formed as two second rings 32 and located proximal from the first ring 31. The first one of the second rings 32 is located distal from the second one of the second rings 32. The first ring 31 and the second rings 32 are connected by four spokes 35 extending inclined from the outer surface of the housing 20 in the deployed state. The spokes 35 extend proximal from the housing 20, inclined to the longitudinal axis and are attached with their distal ends at the distal end of the housing 20. The four spokes are equally spaced around the circumference of the housing 20. The outer diameter of housing 20 is smaller than the diameter of the first ring 31 and the diameter of the first ring 31 is smaller than diameter of the two second rings 32. The more distal one of the two second rings 32 has a smaller diameter than the proximal one of the two second rings 32. Accordingly, the four spokes 35 run straight or slightly curved. The rings 31, 32 and the spokes 35 encircle a distal section and a middle section of the housing 20 and provide fixing of the intra-cardiac device in the right atrial appendage, wherein the electrode 24 is located at or close to the end of the atrial appendage and fixed there such that the electrode 24 has a good and reliable mechanical and electrical connection to the tissue at this location. For more reliable fixation the fixation assembly comprises a plurality of fingers 37 projecting radially from the spokes 25 and the rings 31, 32 in the proximity of the crossings of the spokes 35 with one of the rings 31, 32. The spokes 35 may be welded to the outer surface of the housing 20 or the header 22 of the intra-cardiac device. Other attachment mechanisms may comprise crimping, or shape setting from a singular piece of material.

The rings 31, 32 and the spokes 35 consist of Nitinol wires having a cross section diameter in the range of larger than 7 mm to not more than 40 mm. The inner diameters of the rings 31, 32 and the length of the spokes are, for example, in the range of 5 mm to 25 mm.

In the collapsed state shown in Fig. 2 the spokes 35 abut the outer surface of the housing 20 and run parallel to the longitudinal axis 28. The rings 31, 32 have a slacked form provided by the loading of the device into the implantation catheter device cup. The spokes and rings are in the collapsed state in order to move the device through the patient anatomy during implantation. After accommodation of the intra-cardiac device at the anchoring region, the fixation assembly is unfolded and moved into the configuration shown in Fig. 1.

The above intra-cardiac device provides a reliable fixation for an intra-cardiac device within an atrial wall of the heart or other thin walls of the heart as the acting forces are distributed over a large area by the first circular element and the at least one second circular element. The proposed intra-cardiac device allows easy usage and is associated with low manufacturing costs.

Claims

1. An intracardiac device, particularly an intracardiac pacemaker, for fixation at an anchoring region within the tissue of a patient's heart, particularly with an atrium or atrial appendage, wherein the intracardiac device comprises one electrode (24) attached at its distal end and a housing (20) having a longitudinal axis (28), wherein the intracardiac device comprises a fixation assembly attached at the distal end of the housing (20) and encircling at least part the of housing (20) along its longitudinal axis (28), wherein in a deployed state the fixation assembly comprises one first circular element (31) and at least one second circular element (32) located proximal from the first circular element (31), wherein the first circular element (31) and the at least one second circular element (32) are mechanically connected and the first circular element

(31) has a smaller diameter than an adjacent one of the at least one second circular element (32).

2. The intracardiac device according to claim 1, wherein the first circular element is one first ring (31) and the at least one second circular element is at least one second ring

(32), wherein the first ring (31) and the at least one second ring (32) are mechanically connected by at least two spokes (35) projecting inclined from the outer surface of the housing (20) in the deployed state.

3. The intracardiac device according to claim 1 , wherein the first circular element and the at least one second circular element form a conical spiral comprising at least 1.5 turns.

4. The intracardiac device according to any of the previous claims, wherein the fixing assembly comprises a plurality fixing elements (37), for example barbs, fingers, hooks, tines and/or half-spheres projecting radially outwards from the first circular element (31) and/or the at least one second circular element (31) and/or from the at least two spokes (35). The intracardiac device according to any of the claims 2 and 4, wherein each of the first ring (31) and the at least one second ring (32) forms a slacked ring in a collapsed state. The intracardiac device according to claim 5, wherein each of the first ring (31) and the at least one second ring (32) comprises a preformed kink. The intracardiac device according to claims 2 and 5, wherein the at least two spokes (35) are made of a first material having a first stiffness, and each of the first ring (31) and the at least one second ring (32) are made of a second material having a second stiffness, wherein the first stiffness is larger than the second stiffness. The intracardiac device according to any of the previous claims, further comprising a membrane or fabric supported by and/or attached to fixation assembly, particularly to the first circular element, and the at least one second circular element, and/or at least two spokes. The intracardiac device according to any of the previous claims, wherein the fixation assembly is a component separate from the housing and comprises an additional ring at its distal end, wherein the additional ring has an inner diameter slightly smaller than the outer diameter of the housing (20) at its distal end, wherein the additional ring is removably attached to the distal end of the housing (20) of the intra-cardiac device, wherein particularly the additional ring is made of a superelastic material, preferably ni tinol. The intracardiac device according to claim 9, wherein the housing (20) comprises at least one annular groove at its shell surface for accommodation of the additional ring. The intracardiac device according to any of the previous claims, wherein the fixation assembly has a surface structure comprising a plurality of indentations at its outer surface. - 14 -

12. The intracardiac device according to any of the previous claims, wherein the fixation assembly comprises or is substantially made of a biocompatible material, for example a metal or a plastic material, e.g. a shape memory material, particularly nitinol. 13. The intracardiac device according to any of the previous claims, further comprising a hitch (29) at the proximal end of the housing (20).