CN117357209A

CN117357209A - Bolt taking system

Info

Publication number: CN117357209A
Application number: CN202210753927.7A
Authority: CN
Inventors: 张涵; 候娟; 罗雪莉; 扈昕瞳
Original assignee: Microport Neurotech Shanghai Co Ltd
Current assignee: Microport Neurotech Shanghai Co Ltd
Priority date: 2022-06-29
Filing date: 2022-06-29
Publication date: 2024-01-09

Abstract

The invention provides a bolt taking system, which comprises: a support and a delivery device; the support comprises a plurality of sub-supports which are sequentially connected along the axial direction; the sub-stent has an inner cavity, and the sub-stent has a contracted state and an expanded state, and the expanded state is that the proximal end and the distal end of the sub-stent are recessed toward the inner cavity of the sub-stent, so that the intermediate sections of adjacent sub-stents are close to or in contact with each other and enclose a recessed space. Therefore, the expansion degree of the sub-stent is controlled by utilizing the deformation capability of the sub-stent and under the pulling of the control wire, so that the excessive or insufficient radial supporting force of the stent is avoided, and the vascular injury is relieved. After the sub-stent is expanded, the tension is further increased, and the sub-stent is in an expanded state, so that the two middle sections which are close to or in contact with each other can realize the function of clamping thrombus, and the thrombus taking capacity of the stent is improved. And the concave space formed under the expansion state can accommodate the clamped thrombus, so that the problems of broken bolt escape and broken bolt blockage of blood vessels caused by overlarge cutting force and clamping force are avoided.

Description

Bolt taking system

Technical Field

The invention relates to the technical field of medical instruments, in particular to a bolt taking system.

Background

Acute cerebral stroke is the third leading cause of death today, and is also the leading cause of disability in adults. Among them, ischemic stroke accounts for about 85% of acute stroke. Ischemic cerebral apoplexy is mainly caused by embolism of a larger blood vessel (diameter is more than 2 mm), and the mortality rate of the cerebral arterial thrombosis is 53% -92%. At present, the treatment schemes for embolism are mainly mechanical thrombolysis and drug thrombolysis.

Mechanical thrombus taking is mainly realized by femoral artery puncture, the thrombus taking device passes through the blood vessel to reach the position of vascular occlusion and then passes through the occluded blood vessel, the thrombus is taken out by the thrombus taking device or the thrombus taking catheter, so that the blood flow of the blood vessel is restored, and the thrombus taking purpose is achieved. Compared with the thrombolysis medicine, the mechanical thrombolysis obviously improves the vascular recanalization rate.

However, at present, the design of the thrombus taking support is usually that a hollow structure is cut out on a tubular material, a wave rod of the support is utilized to cut thrombus, meanwhile, the thrombus is embedded into the thrombus, and the thrombus taking support is retracted to achieve the purpose of removing the thrombus. The existing thrombus taking support is of the same diameter, cannot be completely matched with a blood vessel, and is extremely easy to cause overlarge or insufficient radial supporting force released in the blood vessel, so that the inner wall of the blood vessel is damaged or thrombus cannot be removed. In addition, the existing thrombus taking support is of a tubular structure, the wall thickness of the support is thinner, broken thrombus formed by cutting cannot be effectively removed, and the broken thrombus is easy to escape to a distal blood vessel, so that secondary embolism is caused.

Therefore, a new tie down system is needed to solve the above-mentioned problems.

Disclosure of Invention

The invention aims to provide a thrombus taking system, which solves at least one of the problems that the thrombus clamping capacity of a bracket is not enough in the thrombus taking process, the probability of opening a blood vessel at one time is not high, thrombus is cut by the bracket in the thrombus taking process, broken thrombus is formed to block a distal blood vessel, the radial supporting force of the bracket is too large or insufficient, and the thrombus escapes.

In order to solve the above technical problems, the present invention provides a bolt taking system, comprising: a support and a delivery device;

the support comprises a plurality of sub-supports which are sequentially connected along the axial direction; the sub-stent has a lumen and the sub-stent has a contracted state and an expanded state; wherein in the expanded state, the proximal and distal ends of the sub-stent are recessed toward the lumen of the sub-stent such that the intermediate sections of adjacent sub-stents are adjacent or in contact and define a recessed space;

the conveying device comprises a control wire and a pushing rod; the proximal end of the bracket is connected with the distal end of the pushing rod; the control wires extend proximally through all of the sub-stents in turn, and the control wires are operable to control the transition of the sub-stents between the contracted and expanded states.

Optionally, in the thrombus taking system, adjacent sub-brackets are connected through a fixing piece, and a channel for the control wire to pass through is arranged in the fixing piece.

Optionally, in the thrombolysis system, an axial length of the fixing member is smaller than or equal to an axial length of the sub-stent.

Optionally, in the thrombus taking system, the fixing piece and the sub-bracket are integrally formed, and the fixing piece is woven by weaving wires on the sub-bracket.

Optionally, in the thrombus removing system, a developing mark is provided on an outer surface of a distal end of the pushing rod, and a proximal end of the bracket is fixed to the distal end of the pushing rod through the developing mark.

Optionally, in the thrombus removing system, the conveying device further comprises a sleeve, and the sleeve is at least sleeved on the outer surface of the developing mark.

Optionally, in the thrombolysis system, the delivery device further comprises a distal connector, and the distal end of the stent is connected to the distal connector.

Optionally, in the thrombolysis system, a developing mark is provided on the distal connector.

Optionally, in the thrombus removing system, the developing mark is a developing spring or a developing sleeve.

Optionally, in the thrombolysis system, a distal end of the control wire is connected to the distal connector.

Optionally, in the thrombus removing system, a positioning piece is arranged at the distal end and the proximal end of the bracket; the proximal end of the distal end connecting piece and the distal end of the pushing rod are connected with the bracket through the positioning piece respectively; wherein, a channel for the control wire to pass through is arranged in the positioning piece.

Optionally, in the thrombus removing system, the positioning piece is a coil or a tube body; and the outer diameter of the positioning member is smaller than the outer diameter of the distal connector.

Optionally, in the thrombus taking system, a channel is arranged in the pushing rod, and the proximal end of the control wire is arranged in the channel in a penetrating manner; alternatively, the proximal end of the control wire is disposed outside of the push rod.

Optionally, in the thrombus removing system, the conveying device further comprises a handle; the handle is connected with the proximal end of the pushing rod; the control element is connected with the proximal end of the control wire, and the control element controls the control wire to move towards the proximal end or the distal end.

Optionally, in the thrombolysis system, the control element is a slider slidably connected to the handle.

Optionally, in the thrombus taking system, the stent is integrally formed by braiding wires, and all the sub-stents are the same in material or at least some of the sub-stents are different in material.

In summary, the present invention provides a tie-extracting system, comprising: a support and a delivery device; the support comprises a plurality of sub-supports which are sequentially connected along the axial direction; the sub-stent has a lumen and the sub-stent has a contracted state and an expanded state; wherein in the expanded state, the proximal and distal ends of the sub-stent are recessed toward the lumen of the sub-stent such that the intermediate sections of adjacent sub-stents are brought into close proximity or contact and enclose a recessed space. Therefore, the expansion degree of the sub-stent is controlled by utilizing the deformation capability of the sub-stent under the pulling action of the control wire, so that the excessive or insufficient radial supporting force of the stent is avoided, and the vascular injury is reduced. And after the sub-stent is expanded, the tension is further increased, and the sub-stent is in the expanded state, so that the two middle sections which are close to or in contact with each other can realize the function of clamping thrombus, and the thrombus taking capacity of the stent is improved. And the concave space formed in the expansion state can accommodate clamped thrombus, so that the problems of broken bolt escape and broken bolt blockage of blood vessels caused by excessive cutting force and clamping force are avoided.

Therefore, the thrombus taking system provided by the invention can not only avoid overlarge or insufficient radial supporting force of the bracket and control the expansion degree of the bracket, but also improve the thrombus taking capability and avoid broken thrombus escaping.

Drawings

FIG. 1 is a schematic diagram of a thrombolysis system according to an embodiment of the present invention;

FIG. 2 is a schematic view of a fixing member according to an embodiment of the present invention;

FIG. 3 is a schematic view of a stent in an expanded state in an embodiment of the present invention;

FIG. 4 is a schematic view of a stent in an expanded state in an embodiment of the present invention;

FIG. 5 is a schematic illustration of the contact of the intermediate sections of adjacent sub-mounts in an embodiment of the present invention;

FIG. 6 is a schematic illustration of overlapping intermediate sections of adjacent sub-stents in an embodiment of the present invention;

wherein, the reference numerals are as follows:

101-a sub-mount; 102-a fixing piece;

201-distal connector; 202-controlling wires; 203-pushing rod; 204-positioning piece; 205-developing the mark; 206-a handle; 207-control element.

Detailed Description

The invention will be described in further detail with reference to the drawings and the specific embodiments thereof in order to make the objects, advantages and features of the invention more apparent. It should be noted that the drawings are in a very simplified form and are not drawn to scale, merely for convenience and clarity in aiding in the description of embodiments of the invention. Furthermore, the structures shown in the drawings are often part of actual structures. In particular, the drawings are shown with different emphasis instead being placed upon illustrating the various embodiments. It should be further understood that the terms "first," "second," "third," and the like in this specification are used merely for distinguishing between various components, elements, steps, etc. in the specification and not for indicating a logical or sequential relationship between the various components, elements, steps, etc., unless otherwise indicated.

The definition of "proximal" and "distal" herein is: "distal" generally refers to the end of the medical device that first enters the patient during normal operation, and "proximal" generally refers to the end of the medical device that is near the operator during normal operation.

The present embodiment provides a thrombus removing system, referring to fig. 1, the stent includes a plurality of sub-stents 101 connected in sequence along an axial direction; the sub-stent 101 has a lumen, and the sub-stent 101 has a contracted state and an expanded state; wherein in the expanded state, the proximal and distal ends of the sub-stent 101 are recessed toward the lumen of the sub-stent 101 such that the intermediate sections of adjacent sub-stents 101 are brought into close proximity or contact and define a recessed space; the conveying device comprises a control wire 202 and a push rod 203; the proximal end of the bracket is connected with the distal end of the push rod 203; the control wires 202 extend proximally through all of the sub-stents 101 in sequence, the control wires 202 controlling the transition of the sub-stents 101 between the contracted and expanded states.

It can be seen that, in this embodiment, by using the deformability of the sub-stent 101, the expansion degree of the sub-stent 101 is controlled under the pulling action of the control wire 202, so as to avoid the excessive or insufficient radial supporting force of the stent and reduce the vascular injury. And after the sub-stent 101 swells, the pulling force is further increased, and the sub-stent 101 will be in the swelled state, so that the two middle sections which are close to or in contact with each other can realize the function of clamping thrombus, and the thrombus taking capability of the stent is improved. And the concave space formed in the expansion state can accommodate clamped thrombus, so that the problems of broken bolt escape and broken bolt blockage of blood vessels caused by excessive cutting force and clamping force are avoided. Therefore, the thrombus taking system provided by the embodiment not only can avoid overlarge or insufficient radial supporting force of the bracket, and can control the expansion degree of the bracket, but also can improve the thrombus taking capability and avoid broken thrombus escaping.

The thrombolysis system according to the present embodiment is specifically described below with reference to fig. 1 to 6.

With continued reference to fig. 1, the rack provided in this embodiment includes a plurality of sub-racks 101. The sub-bracket 101 is a net-shaped braiding body, has good flexibility, can be deformed by compression, and is convenient for controlling the expansion degree in the process of thrombus extraction. The multiple sub-stents 101 in the stent may be integrally woven by a woven wire, or each sub-stent 101 may be independently woven and formed and connected in sequence along the axial direction to form the stent. Further, the materials of all the sub-brackets 101 may be the same, or may be partially different, or all the sub-brackets may be different. The purpose is to make the sub-stents 101 of different materials have different elastic coefficients so as to facilitate control of the expansion or contraction sequence of the different sub-stents 101 and improve the adaptability of the stent to vessel segments with different diameters. The material of the sub-support 101 includes, but is not limited to, nickel-titanium alloy, cobalt-chromium alloy, DFT material or tantalum alloy. The structure of the support can be single-layer one-press, two-press one-press or two-press, double-layer or multi-structure composite structure. The number of the sub-brackets 101 illustrated in fig. 1 may be 3, or may be 2, 4, 5, or 6, etc., and in this embodiment, the specific number of the sub-brackets 101 is not limited, and meanwhile, the axial lengths of the sub-brackets 101 are not limited, and the axial lengths of the sub-brackets 101 may be the same or different. The stent of different lengths may be selected according to different lesion conditions.

Referring to fig. 1 and 2, adjacent sub-brackets 101 are connected by a fixing member 102, and a channel for the control wire 202 to pass through is provided in the fixing member 102. The fixing member 102 is a part of the bracket and is integrally formed with the sub-bracket 101. Optionally, the fixing member 102 is woven by the woven wires of the sub-stent 101. As shown in fig. 2, two adjacent braided wires at the proximal end or the distal end of the sub-stent 101 are selected, and one of the braided wires is taken as an axis, and the other braided wire is wound around the axis to form the fixing member 102. Of course, the present embodiment is not limited to two braided wires, and may be formed by braiding a plurality of braided wires. The fixing member 102 is used for restraining the sub-stent 101 so as to control the expansion degree of the stent segments and avoid excessive or insufficient radial expansion of part of the stent. In this regard, the fixing member 102 does not deform with the expansion of the sub-stent 101, and generally remains in its original form to restrain the sub-stent 101.

Further, to ensure cutting and capturing of thrombus by the sub-stent 101 and to ensure binding of the sub-stent 101 by the fixing member 102, the axial length of the fixing member 102 is less than or equal to the axial length of the sub-stent 101. Preferably, the axial length of the fixing member 102 is half of the axial length of the sub-mount 101.

With continued reference to fig. 1, the delivery device includes a distal connector 201, a control wire 202, a push rod 203, a handle 206, and a control element 207. The bracket is arranged between the distal end connecting piece 201 and the push rod 203, namely, the distal end of the bracket is connected with the proximal end of the distal end connecting piece 201, and the proximal end of the bracket is connected with the distal end of the push rod 203. Wherein the distal and proximal ends of the stent may be directly connected to the distal connector 201 and the push rod 203. Alternatively, the positioning member 204 is connected to both the distal end and the proximal end of the stent, and then the proximal end of the distal connector 201 and the distal end of the push rod 203 are connected via the positioning member 204.

The positioning member 204 is provided with a channel through which the control wire 202 passes, and the positioning member 204 may be a coil formed by winding a metal wire, for example, a platinum tungsten wire, or a thin-walled tube. Of course, the positioning member 204 may be made of a developing material, such as a radiopaque metal, such as gold, platinum, or tantalum, or a radiopaque polymer material. The positioning member 204 may also be formed of an inner and outer tube, with the proximal or distal end of the stent being positioned between the inner and outer tubes. Wherein, the distal end of the stent is fixedly connected to the proximal end of the distal connector 201 via a positioning member 204, and the distal end of the control wire 202 is also fixedly connected to the proximal end of the distal connector 201, and the connection manner includes, but is not limited to, welding, hot melting, or bonding. Therefore, when the control wire 202 is pulled, the sub-stent 101 is gradually expanded under the fixed connection of the positioning member 204 and the constraint of the fixing member 102, so as to realize expansion control of the sub-stent 101, avoid excessive or insufficient radial support force of the stent, and reduce vascular injury. Further, the outer diameter of the positioning member 204 is smaller than that of the distal connecting member 201, so as to ensure tension stability of the control wire 202, and avoid the distal connecting member 201 from being separated from the original position and embedded into the positioning member 204 due to the overlarge outer diameter of the positioning member 204, thereby damaging the bolting system.

The distal end of the push rod 203 is connected to the bracket, and the proximal end of the push rod 203 is connected to the handle 206. The push rod 203 mainly plays a pushing role for transmitting a pushing force of the proximal end. Thus, the push rod 203 may be a metal tube with a relatively high rigidity, and the material of the push rod may include, but is not limited to, stainless steel, cobalt chrome alloy, nickel titanium alloy, or the like. The push rod 203 may also be a closed tube or a cut hypotube.

Further, in order to control the delivery condition, the outer surface of the distal end of the push rod 203 is provided with a developing mark 205, and the outer surface of the distal end connector 201 is also provided with a developing mark. The developing mark includes, but is not limited to, a developing spring or a developing sleeve. Wherein the proximal end of the stent is fixed to the distal end of the push rod 203 by the development mark 205 of the distal end of the push rod 203. Further, the conveying device further comprises a sleeve (not shown) at least sleeved on the outer surface of the developing mark 205, so as to protect the developing mark 205. Meanwhile, the sleeve is made of high polymer materials, and can also play a role in lubrication, so that the conveying device can be pushed by small force in the microcatheter, and the over-bending capacity of the conveying device is enhanced.

The control wire 202 is used to control the expansion or compression degree of the sub-stent 101, so as to avoid that the radial support force of the stent is too large or insufficient to match with the blood vessel. Wherein, the distal end of the control wire 202 is fixedly connected with the distal end connector 201, so that the distance between the distal end connector 201 and the push rod 203 is reduced or enlarged by pulling the control wire 202, that is, the compressed or expanded state of the stent is changed. In other embodiments, the distal end of the control wire 202 may be directly connected to the distal end of the stent, or the distal end of the control wire 202 may be connected to a positioning member 204 at the distal end of the stent. The proximal ends of the control wires 202 pass through all of the sub-stents 101 and the fasteners 102 within the sub-stents 101 in sequence and extend proximally. Wherein, a channel is arranged in the push rod 203, and the proximal end of the control wire 202 can be arranged inside the push rod 203 in a penetrating way; alternatively, the proximal end of the control wire 202 is disposed outside the push rod 203, i.e., the proximal end of the control wire 202 does not extend into the push rod 203, but only protrudes from the proximal end of the stent to the outside.

The handle 206 is disposed at the proximal end of the push rod 203, so as to facilitate the holding operation of the operator. Wherein, a control element 207 is arranged on the handle 206, the control element 207 is connected with the proximal end of the control wire 202, and the control element 207 controls the control wire 202 to move proximally or distally. Further, the handle 206 is further provided with a guide rail disposed along an axial direction, and the control element 207 is a slider, and the slider is connected to the guide rail and is capable of sliding along the guide rail. Thus, the operator can change the shape of the sub-mount 101 by sliding the slider to pull the control wire 202.

The sub-stent 101 in the thrombus removal system provided in this embodiment has an inner cavity, and has a contracted state and an expanded state under the action of an external force. In the contracted state, as shown in fig. 1, the control member 207 is located at an initial position, and all of the sub-holders 101 are not subjected to tensile force, and are in a relaxed state, and have a flattened circular shape. The oblate stent is convenient to convey in the blood vessel, does not have adverse effect on the blood vessel, and is favorable for conveying.

As shown in fig. 3, after the retrieval system is released to the target area, the control element 207 begins to slide in the V direction. The control element 207 drives the control wire 202 to move along the V direction, so as to reduce the distance between the push rod 203 and the distal connecting member 201, and all the sub-stents 101 are gradually expanded to be cylindrical due to the tensile force, so as to be used for cutting or catching thrombus. Accordingly, the sub-stent 101 begins to enter an expanded state.

As shown in fig. 4, when the control element 207 is further pulled by moving in the V direction, the distance between the push rod 203 and the distal end connector 201 is further reduced under the pulling action of the control wire 202, and the proximal end and the distal end of the sub-stent 101 are recessed toward the inner cavity of the sub-stent 101 under the constraint of the positioning member 204 and the fixing member 102, so as to form a bowl-like shape. The fixing member 102 and the positioning member 204 serve as center points for restraining two ends of the sub-stent 101, the proximal end and the distal end of the sub-stent 101 are recessed toward the inner cavity, the middle section of the sub-stent 101 continues to bulge so that the middle sections of adjacent sub-stents 101 are close to or contact with each other, and a recessed space is defined by the proximal end of one sub-stent 101 and the distal end of the other sub-stent 101. The two middle sections which are close to or in contact with each other are used for clamping thrombus, so that the thrombus taking capacity of the stent is improved. And the formed concave space can accommodate clamped thrombus, so that broken bolts are prevented from escaping due to overlarge cutting force and clamping force, and the broken bolts are prevented from blocking blood vessels.

As shown in fig. 4-6, the proximal and distal ends of the sub-stent 101 may be depressed differently under different degrees of tension, and as shown in fig. 4, the middle sections of the sub-stent 101 may be adjacent to each other with a small gap. Alternatively, as shown in fig. 5, the pulling force is increased so that the intermediate section of the sub-mount 101 is in direct contact, closing the gap. Alternatively, as shown in fig. 6, the pulling force is further increased so that there is an overlapping portion of the middle section of the sub-mount 101. It will be appreciated that, whether the intermediate sections of the sub-stents 101 are close to each other or touch each other, or even overlap exists, the proximal end of one of the sub-stents 101 and the distal end of the other sub-stent 101 adjacent each other enclose a concave space, and the greater the pulling force, the smaller the spacing between the intermediate sections of the sub-stents 101, the more advantageous it is to prevent thrombus from escaping. Therefore, the tension generated by the control element 207 reaches the state of fig. 5 or 6 to be a preferred tension value.

In summary, the sub-stent 101 in the thrombus removal system provided in this embodiment has a deformation capability, so that the control wire 202 cooperates with the pushing rod 203 to control the expansion degree of the sub-stent 101, thereby avoiding the excessive or insufficient radial supporting force of the stent and reducing the vascular injury. And further increasing the pulling force after all of the sub-stents 101 have been expanded, the proximal and distal ends of the sub-stents 101 being recessed toward the lumen of the sub-stents 101. The two middle sections which are close to or in contact with each other are used for clamping thrombus, so that the thrombus taking capacity of the stent is improved. And the formed concave space can accommodate clamped thrombus, so that broken bolts are prevented from escaping due to overlarge cutting force and clamping force, and the broken bolts are prevented from blocking blood vessels. Therefore, the thrombus taking system provided by the embodiment not only can avoid overlarge or insufficient radial supporting force of the bracket, and can control the expansion degree of the bracket, but also can improve the thrombus taking capability and avoid broken thrombus escaping.

It should also be appreciated that while the present invention has been disclosed in the context of a preferred embodiment, the above embodiments are not intended to limit the invention. Many possible variations and modifications of the disclosed technology can be made by anyone skilled in the art without departing from the scope of the technology, or the technology can be modified to be equivalent. Therefore, any simple modification, equivalent variation and modification of the above embodiments according to the technical substance of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A thrombolytic system comprising: a support and a delivery device;

2. The thrombolytic system according to claim 1, wherein adjacent sub-stents are connected by a fixing member, and wherein a passage for the control wire to pass through is provided in the fixing member.

3. The embolectomy system of claim 2 wherein the axial length of the anchor is less than or equal to the axial length of the sub-mount.

4. The embolectomy system of claim 2 wherein the anchor is integrally formed with the subframe and the anchor is woven from woven filaments on the subframe.

5. The embolectomy system of claim 1 wherein an outer surface of the distal end of the pusher bar is provided with a visualization marker and the proximal end of the stent is secured to the distal end of the pusher bar by the visualization marker.

6. The embolectomy system of claim 5 wherein the delivery device further comprises a sleeve that is positioned over at least an outer surface of the imaging indicia.

7. The embolectomy system of claim 1 wherein the delivery device further comprises a distal connector, the distal end of the stent being attached to the distal connector.

8. The embolectomy system of claim 7 wherein said distal connector includes a visualization marker disposed thereon.

9. The tie down system of claim 5 or 8, wherein the developing indicia is a developing spring or a developing sleeve.

10. The embolectomy system of claim 7 wherein the distal end of the control wire is connected to the distal connector.

11. The embolectomy system of claim 7 wherein the distal and proximal ends of the stent are each provided with a locator; the proximal end of the distal end connecting piece and the distal end of the pushing rod are connected with the bracket through the positioning piece respectively; wherein, a channel for the control wire to pass through is arranged in the positioning piece.

12. The thrombolysis system of claim 11, wherein said positioning member is a coil or tube; and the outer diameter of the positioning member is smaller than the outer diameter of the distal connector.

13. The thrombolysis system according to claim 1, wherein a channel is provided in said pushing rod, and a proximal end of said control wire is inserted into said channel; alternatively, the proximal end of the control wire is disposed outside of the push rod.

14. The embolectomy system of claim 1 wherein said delivery device further comprises a handle; the handle is connected with the proximal end of the pushing rod; the control element is connected with the proximal end of the control wire, and the control element controls the control wire to move towards the proximal end or the distal end.

15. The thrombolytic system according to claim 14, wherein said control element is a slider slidably connected to said handle.

16. The embolectomy system of claim 1 wherein the stents are integrally woven from woven filaments and all of the sub-stents are the same material or at least some of the sub-stents are different.