STENT DELIVERY SYSTEM AND HANDLING DEVICE FOR A STENT DELIVERY SYSTEM

A stent delivery system includes a handling device having a housing, a rotatable thumbwheel, and a winding spool. A catheter arrangement includes an inner shaft fixed on the housing. An outer sheath is disposed coaxially to the inner shaft. At least one stent is received radially between the inner shaft and the outer sheath. A flexible pull member engages on the outer sheath and is held on the winding spool to be windable. To release the at least the one stent, the outer sheath is displaceable relative to the inner shaft by winding the flexible pull member on the winding spool. A deflecting and tensioning device is spaced from the winding spool in the proximal direction, is in operative connection to the flexible pull member, and is used to deflect the flexible pull member in a direction towards the winding spool and to tension the flexible pull member.

FIELD

The invention relates to a stent delivery system and to a handling device for a stent delivery system.

BACKGROUND

It is well known to employ intravascular endoprostheses delivered percutaneously for the treatment of diseases of various body vessels. Such intravascular endoprostheses are commonly referred to as “stents”. A stent is a generally longitudinal tubular device of biocompatible material having holes or slots that define a flexible framework that allows radial expansion of the stent, by a balloon catheter or the like, or alternatively by self-expansion due to shape memory characteristics of the material within the body vessel. The flexible framework is configured to allow the stent to be compressed into a smaller outer diameter so that it can be mounted inside a stent delivery system.

The stent delivery system is used to convey the stent to a desired location within the body vessel, and then to release the stent in position. Upon release the stent may self-expand into a larger outer diameter.

WO 2019/053508 A discloses a stent delivery system having a handling device and a catheter arrangement. The catheter arrangement comprises an inner shaft, an outer sheath disposed coaxially to the inner shaft, and a stent which is received radially between the inner shaft and the outer sheath. The inner shaft of the catheter arrangement has a proximal end that is fixed to a housing of the handling device. The stent delivery system further comprises a flexible pull member which, with one end, engages on a proximal end of the outer sheath and, with the other end, is held on a winding spool of the handling device. The winding spool is operatively connected to a thumbwheel that is rotatably mounted inside the housing of the handling device. For release of the stent, the thumbwheel is rotated manually, whereby the winding spool is rotated. The flexible pull member engaging on the winding spool is thereby wound onto the winding spool and, as a result, the outer sheath is displaced relative to the inner shaft in the proximal direction. Due to this proximal retraction of the outer sheath, the stent is released and thus can expand within the blood vessel.

SUMMARY

It is the object of the present invention to provide a stent delivery system that allows a secure handling during the release of the stent. It is a further object of the present invention to provide a handling device for such a stent delivery system, the handling device allowing a secure handling during the release of the stent.

According to a first aspect, a stent delivery system is provided comprising: a handling device having a housing, a thumbwheel mounted in the housing to be rotatable, and a winding spool rotating together with the thumbwheel; a catheter arrangement having an inner shaft, with a proximal end of the inner shaft fixed on the housing, an outer sheath disposed coaxially to the inner shaft, and having at least one stent which is received radially between the inner shaft and the outer sheath; a flexible pull member which, with one end, engages on a proximal end of the outer sheath and, with the other end, is held on the winding spool to be windable; wherein, for release of at least the one stent, the outer sheath is displaceable relative to the inner shaft in the proximal direction by means of winding the flexible pull member on the winding spool; wherein a deflecting and tensioning device is provided spaced from the winding spool in the proximal direction, which deflecting and tensioning device is in operative connection to the flexible pull member, and is used to deflect the flexible pull member in a direction towards the winding spool and to tension the flexible pull member. The solution according to the invention ensures that the proximal end of the outer shaft during winding of the flexible pull member in the proximal direction can be displaced beyond the position of the winding spool. For that purpose, the deflecting and tensioning device is spaced from the winding spool in the proximal direction, wherein the flexible pull member is deflected, starting from the proximal end of the outer sheath and a proximal extension in the direction towards the winding spool. At the same time, the solution according to the invention ensures pre-tensioning of the flexible pull member. For that purpose, the flexible pull member is pre-tensioned using the deflecting and tensioning device. Thereby, an actuation of the thumbwheel free of play is allowed and unintended coming off of the flexible pull member from the winding spool is prevented. As a result, the solution according to the invention allows an exact release of the stent and finally secure handling. The deflecting and tensioning device is intended on the one hand for deflecting and on the other hand for pre-tensioning of the flexible pull member and, thus, presents a particularly advantageous multifunction. Thereby, specific devices for deflecting and for tensioning of the flexible pull member can be omitted and a simple structural design can be achieved. Preferably, the deflecting and tensioning device is configured for a one-time pre-tensioning of the flexible pull member. Such a one-time and/or initial pre-tensioning can be carried out during an assembly of the stent delivery system and compensates for initial play of the flexible pull member. Accordingly, the deflecting and tensioning device can preferably be referred to and/or understood as deflecting and initial play compensation device. Such a initial play compensation is in contrast to a constantly spring-loaded tensioning of the flexible pull member that is variable during an operation of the stent delivery system and which is able to compensate, for example, for a change in the length of the flexible pull member due to operation. Preferably the deflecting and tensioning device includes a base body fixed in the housing and a tensioning element acting on the flexible pull member. Preferably the tensioning element is mounted on the base body to be movable relative to the base body between different tensioning positions in a one-way manner, that is the tensioning element is unable to return to a prior position.

In one embodiment, the deflecting and tensioning device is disposed completely inside the housing. Thereby, the deflecting and tensioning device is manually not accessible, in any case in a ready-for-use condition of the stent delivery system. An inadvertent manipulation of the deflecting and tensioning device and, in particular a variation of the pre-tensioning of the flexible pull member accompanied therewith, is prevented thereby.

In one embodiment, the deflecting and tensioning device includes a base body fixed in the housing and a tensioning element acting on the flexible pull member, which tensioning element is mounted on the base body to be movable relative to the base body between different tensioning positions, wherein the flexible pull member in the different tensioning positions is tensioned by means of the tensioning element to a different extent. The base body can be fixed to the housing in a force-fitting, form-fitting and/or integrally bonded manner. The relative movement of the tensioning element in relation to the base body can be a linear, rotational and/or pivoting movement. The tensioning element can be fixed in the different tensioning positions relative to the base body. In the different tensioning positions the tensioning element acts on the flexible pull member to different extent such that the latter is pre-tensioned to a different extent. For pre-tensioning of the flexible pull member, the tensioning element is displaced relative to the base body and fixed thereon, once the required pre-tensioning is achieved. This occurs preferably manually and preferably on the manufacturing side, i.e. during manufacturing and/or assembly of the stent delivery system. That is, preferably an adjustment of the pre-tensioning and, thus, an actuation of the deflecting and tensioning device by the user of the stent delivery system is not intended.

In one embodiment, the tensioning element is mounted on the base body to be pivotable about a pivoting axis. Thereby, a particularly simple construction of the deflecting and tensioning device is possible. In particular in case that a radial action of the tensioning element on the flexible pull member is provided, a lever action can be achieved by pivotable mounting of the tensioning element on the base body. This is advantageous in view of an achievable pre-tensioning of the flexible pull member.

In one embodiment, the tensioning element includes a tensioning section which acts radially on the flexible pull member, whereby the flexible pull member is tensioned. In the different tensioning positions the tensioning section acts radially on the flexible pull member to a different extent. The flexible pull member is thereby deployed laterally—with reference to a straight extension between the deflecting and tensioning device and the winding spool—whereby a pre-tensioning of different intensity is obtained. In the axial direction, the flexible pull member preferably cooperates with the tensioning section in sliding movement.

In one embodiment, the tensioning element includes a deflecting section on which the flexible pull member is deflected in sliding from an extension in the proximal direction towards the direction of the winding spool. The flexible pull member extends starting from the proximal end of the outer sheath in the direction of the deflecting section, rests in sliding on the latter and is deflected in the direction of the winding spool. Preferably, the flexible pull member is deflected by approximately 180° on the deflecting section. In order to prevent excessive wear of the flexible pull member, the deflecting section preferably has a circular cylindrical outer contour on which the flexible pull member is guided along in sliding.

In one embodiment, the base body includes a passage extending between a distal end and a proximal end of the base body, wherein the inner shaft and the flexible pull member extend through the passage. This embodiment of the invention allows arrangement of the deflecting and tensioning device with particularly low space occupation.

In one embodiment, the deflecting and tensioning device includes a ratchet mechanism provided between the base body and the tensioning element, which ratchet mechanism allows movement of the tensioning element between the different tensioning positions in a first direction to increase the tension of the flexible pull member, and counteracts movement of the tensioning element in an opposite second direction. This is a particularly preferred embodiment of the invention. The ratchet mechanism is preferably disposed completely inside the housing. As a result, an inadvertent manipulation of the ratchet mechanism is prevented. Preferably, the ratchet mechanism is operable exclusively with the housing in an opened condition. For example, this is during manufacture and/or assembly of the stent delivery system. Since the ratchet mechanism counteracts movement of the tensioning element in the second direction, separate fastening of the tensioning element in the tensioning position required for pre-tensioning of the flexible pull member can be omitted.

In one embodiment, the ratchet mechanism includes a first ratchet surface provided on the base body and a second ratchet surface provided on the tensioning element, which second ratchet surface cooperates to register with the first ratchet surface along the first direction, and which is locked in a form-fitting manner against the first ratchet surface along the second direction. This embodiment of the invention allows a particularly simple and robust configuration of the ratchet mechanism and, thus, of the deflecting and tensioning device. The first ratchet surface and the second ratchet surface are preferably each provided with a toothing. These toothing features are designed complementary to each other and register along the first direction and lock in a form-fitting manner along the second direction.

According to a second aspect, a handling device is provided, the handling device having a housing, a thumbwheel mounted in the housing to be rotatable, and a winding spool rotating together with the thumbwheel, wherein a deflecting and tensioning device is provided spaced from the winding spool in a proximal direction, which deflecting and tensioning device is configured for operative connection to a flexible pull member of a catheter arrangement of the stent delivery system. In order to avoid repetition, reference is made to the description of the first aspect and its embodiments. The explanations given there with respect to the handling device of the stent delivery system apply correspondingly to the handling device according to the second aspect.

DETAILED DESCRIPTION

According toFIG.1, a stent delivery system1comprises a handling device2and a catheter arrangement3. The stent delivery system1is intended for use in the treatment of stenosis in blood vessels.

The handling device2has a housing4with a thumbwheel5mounted in the housing4to be rotatable and a winding spool6rotating together with the thumbwheel5. The catheter arrangement3has an inner shaft7with a proximal end8which is at least indirectly fixed on the housing4in a generally well-known manner. Further, the catheter arrangement3has an outer sheath9disposed coaxially to the inner shaft7. The catheter arrangement3includes at least one stent10which is received radially between the inner shaft7and the outer sheath9in a condition of the catheter arrangement3not graphically illustrated in more detail. Moreover, the stent delivery system1includes a flexible pull member11(FIG.4) which, with one end, engages on a proximal end12of the outer sheath9and, with the other end, is held on the winding spool6to be windable. For release of at least the one stent10, the outer sheath9is displaceable relative to the inner shaft7in the proximal direction by means of winding the flexible pull member11on the winding spool6. The above-mentioned release takes place starting from a displacement position of the outer sheath9not illustrated in more detail, wherein a distal end13of the outer sheath9is essentially flush with a distal end14of the inner shaft7. In this condition, the stent10is compressed in the radial direction between an outer shell surface of the inner shaft7and an inner shell surface of the outer sheath9. Following the above-mentioned retraction of the outer sheath9in the proximal direction, the stent10is released in the radial direction, and thereby may expand in the radial direction. With reference toFIG.1, a corresponding released and expanded condition of the first stent10is illustrated.

As is in particular illustrated with reference toFIGS.3and4, the stent delivery system1comprises a deflecting and tensioning device15which is disposed spaced from the winding spool6in a proximal direction and in operative connection to the flexible pull member11. The flexible pull member11is tensioned by means of the deflecting and tensioning device15and deflected from an extension in the proximal direction towards the direction of the winding spool6.

The pre-tensioning of the flexible pull member11caused by the deflecting and tensioning device15allows a play-free actuation of the thumbwheel5and, thus, a precise control of releasing of the stent10. Due to the arrangement of the deflecting and tensioning device15spaced in the proximal direction and the deflection of the flexible pull member11resulting therefrom, the proximal sheath9can be displaced further in the proximal direction than would be allowed during a non-deflected winding of the flexible pull member11on the winding spool6.

Before discussing the specific configuration of the handling device2and the catheter arrangement3, the further features of the deflecting and tensioning device15are explained.

The deflecting and tensioning device15includes a base body16and a tensioning element17. The base body16is fixed in the housing4in a manner described in more detail below. The tensioning element17is mounted on the base body16and movable relative to the latter between different tensioning positions (FIGS.8and9). In that context, the tensioning element17acts on the flexible pull member11to a different extent in the different tensioning positions such that the flexible pull member11is accordingly tensioned to a different extent.

In the embodiment shown, the tensioning element17is fixed on the base body16to be pivotable about a pivoting axis S. The pivoting axis S is provided by a bearing journal18disposed on the base body16, which bearing journal18cooperates in sliding with a bearing bore19formed on the tensioning element17.

The base body16has a cuboid shape (FIGS.6and7). Further, the base body16has a receiving recess A which is disposed on an upper flat face of the cuboid shape, with reference to the drawing plane ofFIG.6. The receiving recess A is provided for receiving the tensioning element17. The tensioning element17, in a condition mounted on the base body16, in which condition the bearing journal18engages in the bearing bore19, is inserted in the receiving recess A flush-mount with the upper flat face of the cuboid shape. This feature is also apparent with reference toFIGS.3and4. In addition this illustration shows that the receiving recess A in the ready-for-use assembled condition is oriented downwards. However, this feature is not mandatory.

Further, the base body includes a passage20extending between a distal end21and a proximal end22of the base body16. The passage20has a circular cylindrical design in the embodiment shown. Further, the passage20is oriented coaxially to the longitudinal direction of extension of the catheter arrangement3in the region of the handling device2. In that context, at least the inner shaft7and the flexible pull member11extend through the passage20(FIGS.4and5).

In the embodiment shown, the base body16manufactured from a dimensionally stable synthetic material. As an alternative, manufacture from metal can be provided.

In the embodiment shown, the tensioning element17includes a tensioning section23and a deflecting section24.

The deflecting section24is disposed on a proximal end25of the tensioning element17which in the ready-for-use assembled condition is oriented approximately flush with the proximal end22of the base body16.

Therein, the deflecting section24adjoins a proximal end of the passage20not described in more detail. For deflection, the flexible pull member11is led out of the proximal end of the passage20and placed on the deflecting section24. During rotational actuation of the thumbwheel5and winding of the flexible pull member11on the winding spool6accompanied therewith, the flexible pull member11slides along the deflecting section24. In the embodiment shown, the flexible pull member11is deflected by approximately 180° by means of the deflecting section24.

In the present case, the deflecting section24is configured in the shape of a circular cylindrical section which is oriented coaxially to the bearing bore19.

For pre-tensioning, the tensioning section23acts in the radial direction of the flexible pull member11. This action has a varying extent in the different tensioning positions (FIGS.8and9). With reference toFIGS.8and9, the tensioning section23disposed on the bottom side of the tensioning element17is concealed by the upper side of the tensioning element17and accordingly drawn in dashed lines. The same applies to the flexible pull member11which for better illustration is drawn in the region of the deflecting section24and the tensioning section23likewise in dashed lines and partially sectioned.

In the embodiment shown, the tensioning section23is disposed approximately in a central position between the proximal end25and a distal end26of the tensioning element17. Further, the tensioning section23has a circular cylindrical outer contour corresponding to the deflecting section24, which outer contour is provided for acting on the flexible pull member11. During winding of the flexible pull member11, the latter slides along the tensioning section23and along the circular cylindrical outer contour, respectively.

Additionally, the deflecting and tensioning device15includes a ratchet mechanism27,28provided between the base body16and the tensioning element17. The ratchet mechanism27,28permits relative movement of the tensioning element17in a first direction R1and counteracts an opposite relative movement in a second direction R2. The directions of movement R1, R2of the tensioning element17are pivoting movements relative to the base body16about the pivoting axis S, in the present case. A displacement of the tensioning element17along the first direction R1causes pre-tensioning of the flexible pull member11.

In the embodiment shown, the ratchet mechanism27,28includes a first ratchet surface27provided on the base body16and a second ratchet surface28provided on the tensioning element17. The first ratchet surface27and the second ratchet surface28register along the first direction R1. Along the second direction R2the ratchet surfaces27,28cooperate in a form-fitting manner such that a movement of the tensioning element17in the second direction R2is blocked.

The second ratchet surface28is disposed on the distal end26of the tensioning element17. The first ratchet surface27is disposed in the region of the distal end21of the base body16and faces the proximal direction of the receiving recess A.

Further, the tensioning element17has an abutment section29which cooperates in a form-fitting manner with a counter-abutment section30of the base body16for limiting the pivoting displacement of the tensioning element17. This feature is illustrated with reference toFIG.9. The tensioning position of the tensioning element17apparent therein is in that context an end position along the first direction R1. In the present case, the abutment section29is disposed on the proximal end25of the tensioning element17and protrudes from the deflecting section24outwards in the radial direction. The counter-abutment section30is disposed on the proximal end22of the base body16.

Moreover, the tensioning element17includes a guiding section31which is disposed in the region of the tensioning section23and provided by two guiding partial sections31a,31bmutually spaced in the axial direction of the tensioning section23. By means of the guiding section31, on the one hand, the flexible pull member11is guided in the vicinity of the tensioning section23such that an unintended lateral slipping of the flexible pull member11is prevented. Moreover, the tensioning element17is guided in sliding movement on the base body16by means of the guiding section31which, for that purpose is provided with a guiding groove32. The guiding partial section31a(FIG.10) engages in sliding in the guiding groove32.

As is further illustrated in particular with reference toFIGS.3and4, in the present case, the deflecting and tensioning device15is disposed completely inside the housing4. In the ready-for-use assembled condition of the housing4, the deflecting and tensioning device15is manually not accessible by a user of the stent delivery system1. In that context, manual adjustment of the pre-tensioning of the flexible pull member11by a user is also not provided. Rather, adjustment of the pre-tensioning takes place during manufacture and/or assembly of the stent delivery system1with the housing4in an opened condition. In this opened condition of the housing4, which in the present case has a left housing half4aand a right housing half4b,the deflecting and tensioning device15is manually accessible.

Starting from the condition apparent with reference toFIG.8, wherein the tensioning element17occupies a first tensioning position, the tensioning element17is displaced by pivoting along the first direction R1to increase the pre-tensioning. For that purpose, the tensioning element17may be moved in the first direction R1, for example, using the thumb of one hand in the region of the distal end26.

What is caused thereby is that the tensioning section23acts in the radial direction on the flexible pull member11so that the latter—in relation to the drawing plane ofFIGS.8and9—is pushed laterally to the right. Thereby, any play in the flexible pull member11can be removed and a pre-tensioning be caused. During such a movement of the tensioning element17, the ratchet surfaces27,28cooperate to register and prevent an opposite movement along the second direction R2.

Further details of the configuration of the handling device2and the catheter arrangement3will be discussed below, however are not to be considered as mandatory features in view of the present invention.

In the present case, the housing4is manufactured from a dimensionally stable synthetic material. As it is further apparent with reference toFIGS.1and2, the housing4provides a handle which may be grasped by a hand, such that the thumb of the respective hand is placed in the region of an upper side of the housing4for rotating actuation of the thumbwheel5.

The thumbwheel5is mounted in the housing4to be rotatable about a rotation axis D (FIG.3) and protrudes, in the radial direction of the thumbwheel5, from a recess of the housing4not described in more detail. As a result, the thumbwheel5is manually operable in the above described manner. The rotation axis D is perpendicular to the proximal displacement direction of the outer sheath9and—during conventional handling—in approximately horizontal orientation.

The winding spool6is orientated coaxially to the thumbwheel5and connected to the thumbwheel in a torque-transmitting manner. As a result, the winding spool6is rotatable together with the thumbwheel5about the rotation axis D. In a not shown embodiment, the winding spool6can be provided integrally with the thumbwheel5. In the embodiment shown, the winding spool6is disposed completely inside the housing4.

The catheter arrangement3extends in the region of the handling device2between a distal end and a proximal end of the housing4within the latter. The inner shaft7includes a lumen, not apparent in more detail, which extends between the proximal end8and the distal end14. In the region of the proximal end8, the lumen leads into a Luer port P which is fixed to the proximal end of the housing4in a generally well-known manner. On its distal end14, the inner shaft7includes a catheter tip. The inner shaft7has a flexible design. The outer sheath9is manufactured from a braided material, in the embodiment shown, and connected in the region of its proximal end12(FIG.4) to the flexible pull member11for transfer of pulling force, in a generally well-known manner. In the embodiment shown, the first stent10is a self-expanding stent.

Furthermore, in the present case, the catheter arrangement3includes a plurality of stents10,10′,10″.

In that context, in addition to the stent10which may also be referred to a first stent10, a second stent10′ and a third stent10″ are provided, which stents are held in the radial direction between the inner shaft7and the outer sheath9, in a manner corresponding to the first stent10. The stents10,10′,10″ are spaced from each other in the axial direction.

Further, the handling device includes a guiding tip T which is disposed on a distal end of the housing4and is held between the housing halves4a,4b.The catheter arrangement3extends, in the region of the distal end of the housing4, through the guiding tip T in the axial direction.

Furthermore, the handling device2includes a locking and unlocking mechanism L which is intended for locking and unlocking the rotational mobility of the thumbwheel5, and thus also the winding spool6. However, the locking and unlocking mechanism L is not mandatory. Therefore, a more detailed description thereof is omitted for reasons of brevity.