Patent Application
20180140206
This application claims the benefit, under 35 U.S.C. § 119, of European patent application EP 16200256.2, filed Nov. 23, 2016; the prior application is herewith incorporated by reference in its entirety.
The invention relates to a medical implant, in particular miniaturized implants implanted in the cardiovascular system, and systems for intravascular implantation thereof.
An example of implants of this kind is provided by implantable pressure sensor devices, in particular a miniature pressure sensor device, which can be implanted in an animal or human body. Pressure sensor devices including microelectromechanical systems (MEMS) and associated chip systems are known in the art. For example, pressure sensor devices with MEMS chips are used for electrical implants for improving the heart function of a patient. Chip systems which can be used for these purposes on the one hand have to deliver sufficiently precise measurement results, and on the other hand must have very small dimensions, so that they can be implanted without difficulty and do not limit the physiological activity of the organism, for example for blood pressure measurements in the pulmonary artery.
Another example of such an implant is provided by pacemaker implants which are conveyed intravascularly for implantation so as to ultimately be implanted in a blood vessel, for example miniaturized cardiac pacemakers without long electrode leads (so-called ‘leadless’ pacemakers).
A technical challenge in conjunction with such implants is that of conveying the implant through the cardiovascular system. In spite of miniaturization of the implant dimensions, difficulties can occur when conveying the implant through the cardiovascular system, in particular if the implant has to be passed through narrow, winding blood vessels having a small bend radius. A second problem is the placement and reliable fixing of the implant at the implantation site, i.e. in contact with the blood flow. A stationary fixing of the implant is necessary for this purpose, without significant disruption to the blood flow. An uncomplicated implantation system and method as well as a simple possibility for explanation are desirable.
U.S. patent publication No. 2016/0082270 A1 describes a fixing unit which is configured to anchor a medical implant in a patient.
The prior art presents systems based on wire loops that are attached to the sides of the implant and that hold the implant in a blood vessel. Systems of this kind, however, have a number of disadvantages: The wire loops are relatively tightly curved in the implanted state, thus heavily stressing the material. Furthermore, the wire loops take up a relatively large amount of space and the connection of the loops to the housing, which at the same time constitutes an electrical bushing, can only be produced in a complex manner.
Stent-based solutions for the securing of implants in a blood vessel are also known. Stent-like solutions have the great advantage that they are relatively rigid and therefore are difficult to guide through blood vessels. In addition, stent systems tend to migrate, i.e. there is the possibility that the implant, over time, will not remain at the implantation site, and instead ‘migrates’ in the blood vessel. Stent systems and associated implantation systems are also complex and costly to produce.
One object of the present invention is therefore to provide a medical implant which can be conveyed in a simple manner through curved blood vessels of the cardiovascular system. A further object of the present invention lies in providing a medical implant which can be implanted in the cardiovascular system in a permanent and stationary manner. A further object can also be considered that of providing a medical implant which can be implanted and explanted in a simple way.
Another object of the present invention is to provide systems for implanting a medical implant of the aforesaid type, which systems have an uncomplicated structure and in addition are easy to use and easy to produce.
A further object can be considered that of providing a medical implant which, after implantation in the cardiovascular system, does not significantly adversely affect or hinder the blood flow.
In accordance with the present invention, a medical implant for intravascular implantation is proposed, which implant has an implant housing and at least a first and a second conveying element, which are arranged in one plane on the implant housing. Here, the first conveying element is mounted rotatably about a first rotation axis, and the second conveying element is mounted rotatably about a second rotation axis.
In conjunction with the present invention, any types of medical implants which are implanted intramuscularly and/or have to be conveyed through blood vessels during the implantation process are conceivable. Examples of these are cardial implants, for example pacemakers, in particular pacemaker implants without electrode leads (what are known as ‘leadless’ implants) for implantation in a chamber of the heart, cranial implants, stent or coil implants, and the like. One embodiment provides a miniaturized pressure sensor for implantation in the pulmonary artery as medical implant, so as to be able to take blood pressure measurements over a longer period of time.
The implant housing may be made of material which is biocompatible and at the same time robust with respect to influences in the surrounding environment of the implantation site. A suitable material is titanium, for example.
The housing geometry may be selected in such a way that it is possible for the implant to be conveyed through a blood vessel or implanted in a blood vessel in a simple manner.
In the context of the invention, a conveying element is understood to mean a component which can be used to simplify the conveying of the implant through blood vessels to the implantation site. In accordance with the invention, the conveying elements may be rotatably mounted. The first conveying element and the second conveying element may be arranged in the same plane on the implant housing. The first conveying element and the second conveying element may be used in order to convey or transport the medical implant inside a body of a subject, e.g. intramuscularly or intravascularly. Thus, the first conveying element and the second conveying element may also be called the first transporting element and the second transporting element, respectively.
In accordance with an embodiment of the present invention, the implant housing has a shape with a proximal end and a distal end, wherein the first conveying element is arranged close to the proximal end and the second conveying element is arranged close to the distal end. Here, the first and the second conveying element may be arranged on at least one side outer surface of the implant housing.
A suitable geometric basic shape of the outer housing is a cube, for example; a cylinder, an ellipsoid, or any bar-like elongate shape is also conceivable. Here, shapes with rounded corners and edges would be advantageous, so as to reduce the flow resistance, so that the implantation process is simplified and thrombus formation at the implant is hindered. The shape can have defined flat outer surfaces, as is the case with a cube, and curved outer surfaces, as is the case with an ellipsoid or the lateral surface of a cylinder. If the medical implant for example has a cuboid outer shape, the conveying elements can be arranged on a side outer wall, wherein the first conveying element is arranged close to the proximal end of the implant housing, and the second conveying element is arranged close to the distal end of the implant housing. Here, the conveying elements can be formed by parts of the implant housing or can be connected to the implant housing by a screwed, welded, soldered or glued connection, or the like. If the implant housing a cylindrical with a lateral surface and two base faces, the at least two conveying elements can be arranged along a line on the lateral outer surface running parallel to the height of the cylinder.
Within the scope of this application, proximal and distal are understood in relation to the operator. The proximal end of the implant is closest to the operator during implantation, and the distal end is distanced furthest from the operator during the insertion of the implant.
The two points at which the first and second conveying elements are arranged may have a relatively large distance from one another and may be connected to one another directly where possible, wherein this is to be understood in the sense that a path leading along the outer housing should run from the first point to the second point as directly as possible and in the straightest line possible. In this way, it is achieved that a guide apparatus for implantation, for example a guide wire or the like, can be guided easily and directly from the first to the second conveying element and can be coupled to the conveying elements, wherein the geometry of the implant housing is adapted to the guide wire or nestles against the guide wire to the greatest possible extent.
In one embodiment of the present invention the first and second rotation axes may be oriented parallel to one another. Furthermore, the first and second rotation axes can be configured in such a way that they are oriented perpendicular to the longitudinal axis of the implant housing. Alternatively or additionally, the rotation axes can be oriented perpendicular to the plane in which the first and second conveying element are arranged.
If the first and the second conveying element are coupled to a guide apparatus for implantation, for example a guide wire or the like, the rotatably mounted conveying elements thus provide a certain degree of movement of the implant relative to the guide apparatus. This is advantageous in the case of implantation, since the implant is not rigidly coupled to the guide apparatus and can therefore be conveyed more easily through blood vessels having a small diameter and small bend radius.
With the orientation of the rotation axes, it can be achieved that the length of the implant is oriented substantially tangentially to the curve of the bend of the portion of the guide apparatus at which the medical implant is disposed.
Within the scope of this application, the longitudinal axis is understood to mean the axis along which the implant has its greatest extent.
In accordance with one embodiment according to the invention, the first and the second conveying element may be configured to interact with a guide wire.
In the sense of the invention, in this regard, other apparatuses which can be used in order to intravascularly convey implants, such as catheter systems or the like, are also included besides a guide wire. In accordance with the invention, the interaction of the conveying elements with the guide wire is understood to mean any form of a coupling making it possible to convey the medical implant by means of the guide wire.
In one embodiment of the invention, the conveying elements may each have a holder member, wherein the holder member is configured to receive a guide wire. Here, the holder member may have the form of a ring, an eyelet, a loop, or a hook.
The guide wire can thus be threaded for example through ring-like or eyelet-like holder members. In the case of loops and hooks, the guide wire is clamped or hooked respectively, wherein a mechanism which secures the coupling, for example by latching or engagement, can be used. Here, the holder members should be movable along the guide wire, in other words the holder members should not be rigidly connected to the guide wire. Other embodiments for the holder members are also conceivable, which likewise offer a coupling of the described kind between conveying elements and the guide wire, for example rail, bracket or tunnel systems or the like.
In an embodiment of the invention the medical implant may have a fixing structure with at least two holder units, wherein the fixing structure can adopt an expanded state and a collapsed state. Here, the fixing structure may be configured in the expanded state to fix the medical implant at an implantation site.
In one embodiment of the invention the holder unit may have the form of a ring, an eyelet, a loop, or a hook.
For example, the fixing structure can be embodied in the form of legs, flaps, a framework, lattice, mesh, or stent.
In the sense of the invention a collapsed state of the fixing structure is understood to mean a form in which the fixing structure has an outer geometry suitable for intravascular conveyance. An expanded state is understood to mean a form in which the fixing structure has an outer geometry suitable for fixing/anchoring/securing the fixing structure itself and also the medical implant in a blood vessel.
If the fixing structure is embodied as legs, flaps or a framework, these are in the collapsed state when they are closed and are in the expanded state when they are folded out. The same is true for a lattice-like, mesh-like or stent-like fixing structure, which can assume the collapsed and expanded state by folded up or unfolded respectively.
The fixing structure may be made of biocompatible material suitable for permanent implantation in the blood flow. After reaching the implantation site, the fixing structure can be expanded. The holder units are coupled to the fixing structure and are configured to hold the fixing structure in the collapsed state.
The holder units can be fixedly connected to the fixing structure. For example, they are arranged on a proximal end and/or distal end of the fixing structure and may have the form of a ring or are similar to a ring. Rail, bracket or tunnel systems or the like are also conceivable.
In one embodiment the holder units can be connected to a cord or the like. This would simplify an explantation of the implant, for example in that the cord is caught over a catheter.
In accordance with one embodiment of the invention, the holder units of the fixing structure may be configured to interact with a guide wire so that the fixing structure is in the collapsed state.
The holder units may be configured so that they can be coupled to the guide wire in such a way that the fixing structure is held in the collapsed state. To this end, the guide wire can be received for example by the holder units.
The guide wire can thus also be threaded for example through ring-like or eyelet-like holder units, similarly to the holder members. In the case of loop-like or hook-like holder units, the guide wire is clamped or hooked respectively, wherein a mechanism which secures the coupling, for example by latching or engagement, can be used. Here, the holder units should be movable along the guide wire, i.e. the holder units should not be rigidly connected to the guide wire. Other embodiments for the holder units are also conceivable, which likewise offer a coupling of the described type between conveying elements and the guide wire, for example rail, bracket or tunnel systems or the like.
In one embodiment of the invention the fixing structure may comprise at least two limbs made of flexible material. Here, the limbs are closed in the collapsed state and are folded out from one another in the expanded state. Furthermore, it is conceivable that each limb has a meandering and/or zigzagging portion.
The limbs may be configured, in the collapsed state, to provide an extension of the implant housing so that the overall diameter of the medical implant is not increased or is only slightly increased. At a desired implantation site within a blood vessel, the limbs can be brought into the expanded state. The overall diameter of the implant is then significantly increased, and the limbs are folded out from one another and each contact the inner wall of the vessel at one of their ends, so that the force can be transferred to the inner wall of the vessel (for example by wedging or pressure) in order to support the medical implant in the blood vessel and hold it at that point. For example, the unfolded limbs form a V shape and fix the implant in the blood vessel in that shape. A V shape is characterized in that it has an anisotropic flow resistance, i.e. an implant fixed in the blood vessel puts up a resistance to the blood flow, which resistance is dependent on the direction of blood flow. By corresponding placement of the implant, the implant can thus be prevented from ‘migrating’ after a certain time, i.e. it can be prevented from moving in a direction with the blood flow. In this regard, other forms for the fixing structure suitable for the aforementioned purpose with anisotropic flow resistance in the expanded state are also conceivable.
In accordance with one embodiment of the invention the fixing structure may be made at least in part a flexible material, since the implant can be conveyed through blood vessels with lower resistance during the implantation, and, after fixing of the implant in the blood vessel, a certain adaptation of the limbs to the cyclic forces occurring due to the blood flow in the vessel takes place, so that the service life of the material is extended. The degree of flexibility should be selected in accordance with the described properties to be satisfied.
In accordance with one embodiment, the proximal ends of the limbs may have a meandering portion, which may be the portion that contacts the inner wall of the vessel. The contact face of the fixing structure on the inner wall of the vessel is thus increased, and the pressure applied by the fixing structure to the inner wall of the vessel is thus reduced. Furthermore, the elasticity of the fixing structure in the region of the contact faces is increased. It is thus achieved that the contact faces run tangentially to the vessel wall. This is advantageous since on the one hand the holding of the implant in the vessel is increased and on the other hand the risk of the limbs cutting into the vessel wall decreases. Other shapes and patterns for the portion of the limbs that provide the effect are also included, for example zigzag shapes, step shapes or other repetitive geometries.
In accordance with an embodiment of the present invention, the fixing structure may be coupled to at least one mechanical spring. Here, the mechanical spring may be tensioned when the fixing structure is in the collapsed state and may be in the rest position when the fixing structure is in the expanded state.
The mechanical spring according to the invention can be provided for example in the form of a leg spring, tab spring, helical spring or similar spring. For example, the spring can be arranged on or integrated in or inside the implant housing. If the fixing structure has legs or limbs as in the described embodiments, the legs or limbs can be coupled at their end facing the implant housing to the spring or can transition into a spring. In the described embodiment with two limbs which fold out in a V shape, the spring can be arranged between the two limbs (i.e. at the apex of the V), wherein the spring is secured to an end of the implant housing. In one embodiment, the limbs each have a holder unit at the proximal end, by which they can receive a guide wire. For this purpose, the limbs have to be closed, so that the holder units are oriented in a line and the guide wire can be received. In order to close the limbs, the mechanical spring is tensioned, and the fixing structure is in the collapsed state. If the guide wire is retracted, so that it is no longer received by the holder units, the fixing structure immediately adopts the expanded state, for example by folding out the two limbs into the V shape, caused by the restoring force of the spring, which moves the fixing structure back into the rest position.
In accordance with one embodiment of the invention, the fixing structure may be made at least in part or completely of a shape-memory material, in particular a shape-memory alloy such as nitinol.
Shape-memory materials are characterized in that they can be deformed under specific external circumstances, but after deformation can resume their initial form by means of a stimulus. For example, a stimulus of this kind can be constituted by a change in temperature.
For example, the shape-memory material can be selected in such a way that it resumes its initial form at body temperature (‘austenite state’). The expanded state may be selected as the initial form for the fixing structure. The fixing structure, prior to implantation, is first converted into the deformable state (‘martensite state’, for example by cooling), shaped into the collapsed state, and coupled to a guide wire, so that the holder units receive the guide wire. In the event of implantation, the shape-memory material is heated again by the body temperature to a temperature above the transition temperature. Here, the fixing structure is still held in its collapsed state by the guide wire, this state being referred to as the stress-induced martensite state. As soon as the implant has been conveyed to the desired implantation site and the guide wire has been removed, the guide structure regains its initial form (the expanded state, or austenite state).
The use of a shape-memory material for the fixing mechanism enables its change from the collapsed to the expanded state without use of an additional mechanical energy store.
In an embodiment of the present invention the medical implant may have a gripper unit. The gripper unit can be embodied for example as a ring, eyelet, hook or the like and can be arranged at the proximal end of the medical implant. Here, the gripper unit serves to attach the implant to a component for pushing or pulling the implant along the guide wire. The gripper unit can also be used after implantation for adjustment of the implantation site, or for explantation, by being grasped or held by a catheter or the like, so that the medical implant can be moved.
The present invention also contains a system for intravascular implantation of a previously described medical implant, wherein the system has at least one flexible guide wire and an elongate slider unit. Here, the implant, the guide wire and the slider unit may be arranged in such a way that
a) the guide wire interacts with the first and second conveying element of the implant, wherein the first and second conveying element each may have a holder member, which holder members received the guide wire; and
b) the slider unit interacts with the guide wire, so that the slider unit can be moved along the guide wire, wherein the slider unit is designed to push and/or to pull the medical implant along the guide wire.
In another embodiment of the system according to the invention for intravascular implantation, the slider unit may contain a flexible shaft, referred to hereinafter as a slider shaft, and a slider module, wherein the slider shaft surrounds a lumen and the slider module is arranged at the proximal end of the slider shaft. Here, the guide wire may be arranged at least in part within the lumen and the slider module interacts with the medical implant in such a way that the implant can be at least held, pulled and/or pushed by the slider module. In this way, by means of the slider unit, the position of the implant in relation to the guide wire can be controlled by the slider module.
The holder members may receive the guide wire so that the implant is coupled to the guide wire, but can move freely there along. For example, a coupling in which the holder members are configured as ring-, eyelet-, loop-, hook-, rail-, bracket- or tunnel-like members or are designed in a form similar to those described can also be implemented.
A system for intravascular implantation which makes it possible to convey implants through blood vessels having a small diameter and small bend radius in a simple manner is created by the system according to the invention and described embodiments. In addition, the system has an uncomplicated structure and can be preassembled by the manufacturer, thus sparing a laborious and costly assembly directly on site at the time of implantation.
In one embodiment of the system according to the invention, the medical implant and the guide wire may be arranged in such a way that the fixing structure is arranged in the proximal position and the implant housing is arranged in the distal position. Alternatively, the implant housing can be arranged in the proximal position and the fixing structure can be arranged in the distal position.
The slider unit can be embodied as a pusher catheter, which for example is used typically for the catheterization of the cardiovascular system. A system which can grip and hold the medical implant via the gripper unit in order to push or pull the implant can also be selected as slider unit. In this way, the operator is provided at the time of implantation with greater freedom for conveying and placing the implant, and in particular the adjustment of the implant position is thus simplified. If the implant is arranged on the guide wire so that the fixing structure is in the proximal position and the implant housing is in the distal position, the fixing structure itself, parts thereof or the holder units can thus be used as gripper units. If, by contrast, the implant housing is arranged in the proximal position and the fixing structure is arranged in the distal position, the gripper unit can be arranged for example at the proximal end of the implant housing, which can be gripped and held by the slider unit. A slider unit of this type with gripping function can be configured in cooperation with the guide wire in such a way that the grip is released when the guide wire is retracted.
In one embodiment of the described system for intravascular implantation of a described medical implant, the system does not comprise a slider unit. Instead, the system has a long flexible shaft which surrounds a lumen and has a proximal end and a distal end. The implant and the guide wire are arranged at least in part within the lumen, wherein the guide wire is received by the conveying elements. Here, the implant may be arranged close to the distal end of the flexible shaft, wherein the fixing structure of the implant is oriented towards the distal end of the flexible shaft, that is to say in the direction in which the shaft is advanced in the vascular system. The fixing structure is held here in the collapsed state by the guide wire. The flexible shaft, together with guide wire and implant in the inner lumen, is advanced intravascularly to the implantation site, where the implant is released from the flexible shaft with the aid of the following process. The implant within the flexible shaft is advanced using the guide wire in the distal direction until the fixing structure protrudes in part from the flexible shaft. The implant housing should still be disposed within the flexible shaft. The guide wire is then retracted in the proximal direction, so that the fixing structure is brought into the expanded state, so that the distal part of the fixing structure is supported against the inner wall of the vessel, wherein the proximal part of the fixing structure is arranged within the flexible shaft. The flexible shaft is then retracted in the proximal direction, wherein the implant is released from the flexible shaft and is held at the implantation site by the fixing structure. In this way, a sudden release of the implant is prevented and a controlled release from the flexible shaft is made possible.
In accordance with an embodiment according to the invention of the system for intravascular implantation, the medical implant may have a previously described fixing structure with at least two holder units as described before, wherein the fixing structure can adopt an expanded and a collapsed state. Furthermore, the holder units are configured to interact with the guide wire in that the guide wire is received by the holder units, so that the fixing structure is in the collapsed state. Here, the fixing structure is configured to transition into the expanded state as soon as the guide wire ceases to interact with the holder units.
In accordance with one embodiment, the holder units may be configured in the form of rings, eyelets, loops, hooks, rails, brackets, tunnels or in a form similar to those described. Similarly to the holder members, the holder units may also be configured so that they ensure a coupling of the fixing structure to the guide wire, wherein it should be possible however that the fixing structure and with it the medical implant can be moved along the guide wire. The fixing structure may be held in the collapsed state when the holder units are coupled to the guide wire. As soon as this coupling is cancelled, for example in that the guide wire is retracted, the fixing structure adopts the expanded state.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a medical implant and a system for intravascular implantation, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
In the drawings, functionally like or identically acting elements are referenced in each case by the same reference signs. The drawings are schematic depictions of the invention. They do not show specific parameters of the invention. The drawings also present merely typical embodiments of the invention and are not intended to limit the invention to the depicted embodiments.
The embodiments and/or features of the medical implant according to the invention and of the system for intravascular implantation of an implant of this kind depicted in the drawings can also be combined with one another and are not intended to be limited to the example and features thereof shown in the drawings.
Referring now to the figures of the drawings in detail and first, particularly to
It will be apparent to those skilled in the art that numerous modifications and variations of the described examples and embodiments are possible in light of the above teaching. The disclosed examples and embodiments are presented for purposes of illustration only. Other alternate embodiments may include some or all of the features disclosed herein. Therefore, it is the intent to cover all such modifications and alternate embodiments as may come within the true scope of this invention.
The following is a summary list of reference numerals and the corresponding structure used in the above description of the invention:
| Number | Date | Country | Kind |
|---|---|---|---|
| 16200256.2 | Nov 2016 | EP | regional |
