Patent Description:
Bioabsorbable (biodegradable) polymer coronary stent products can bring benefits to the luminal diameter of coronary arteries and are suitable for use in the treatment of ischemic heart disease caused by primary coronary abnormalities. Such a bioabsorbable polymer stent product mainly consists of a polymer stent, a drug coating and a balloon-expandable delivery system.

Stents are generally categorized into metal and polymer ones, and metal stents are further grouped into biodegradable and non-biodegradable. At present, most metal stents are non-biodegradable, while most polymer ones are biodegradable. In many therapeutic applications, once a commonly-used metal stent is implanted, it will permanently remain in the patient's body, posing long-term risks to the patient's health. By contrast, a polymer stent stays in the body only for a limited period of time during which the stent achieves its expected goal such as blood vessel patency or drug delivery.

After achieving its therapeutic goal, a biodegradable stent will degrade into absorbable and metabolizable products in the body environment and eventually disappear. Before a stent is delivered into a diseased blood vessel, it is configured in a squeezed state of being squeezed and secured onto the surface of a balloon. During use, the squeezed stent will be delivered along with the balloon to the diseased blood vessel, and the balloon is then inflated so that the stent expands synchronously with the balloon and finally presses against the vessel wall.

Metal stents have good shape stability. Once a metal stent is squeezed to a certain diameter, it will substantially maintain the same diameter from then on. Therefore, metal stent products are basically free of the risk of diametrical expansion over time from packaging to use. On the other hand, polymer stents are made of polymeric materials that are more or less resilient, so they tend to experience more significant radial resilience after being moved from the presser. As a result, polymer stents will expand in radial dimension over time after being squeezed. However, traditional protective sheaths of a single-layered design tend to be unable to provide sufficient resistance to such expansions for stent diameter maintenance. Therefore, there is a need to address the challenges associated with securing a polymer stent to a delivery balloon and maintaining a diametrical dimension thereof favorable to the delivery system up until the time when the stent system is delivered to a target site within a body.

Conventional stents such as that disclosed in <CIT> require complicated operations and suffer from a lack of compatibility with surgical environments.

<CIT> discloses a device for protecting the surface of a coated stent during its packaging, shipping, subsequent removal from the packaging and handling prior to introduction into a guiding catheter. <CIT> discloses protective sheaths for scaffolds and stents crimped to a delivery balloon.

Those skilled in the art have been long seeking solutions to the problem that conventional polymer stent products expand in radial dimension over time from packaging to use.

It is an objective of the present invention to provide a protection device for stent and a medical device, which can be operated easily and radially restrain and protect a stent.

To solve the above technical problem, the present invention provides a protection device for stent, comprising a sheath, a first grip and a second grip, the sheath being configured to hold a stent, the first grip is configured to be able to be driven to move toward the second grip to cause a first portion of the sheath to move away from a second portion thereof, so that the stent is allowed to be removed from the sheath.

Optionally, in the protection device for stent, the first grip is formed by extending the first portion, and the second grip is formed by extending the second portion.

Optionally, in the protection device for stent, the first grip and the second grip are connected to each other by a connecting member.

Optionally, in the protection device for stent, the connecting member is a spring, a spring strip or a shaft.

Optionally, in the protection device for stent, further comprising a first fastener and a second fastener, the first fastener being connected to the first grip, the second fastener being connected to the second grip, the first fastener and the second fastener being configured to engage each other to limit relative position of the first grip to the second grip.

Optionally, in the protection device for stent, each of the first grip and the second grip is provided thereon with a number of anti-slipping means.

Optionally, in the protection device for stent, an end of the first portion away from the first grip is integral with an end of the second portion away from the second grip.

Optionally, in the protection device for stent, the first grip defines an axially-extending opening through which the second grip is inserted so that the second grip opposes the first grip.

Optionally, in the protection device for stent, the connecting member is a spring strip with two ends disposed close to respective centers of the first grip and the second grip.

According to the invention, in the protection device for stent, the first portion and/or the second portion comprise(s) a frame and elastomer filler that is filled in the frame and defines a cavity for receiving the stent.

Optionally, in the protection device for stent, further comprising a protective layer provided on an inner surface of the sheath.

Accordingly, the present invention further provides a medical device, comprising a stent squeezed within a balloon catheter, a coiled tube and a protection device for stent as defined above, the protection device being connected to the coiled tube.

Optionally, in the medical device, the coiled tube comprises an engagement tough configured to be received in the sheath so that the engagement tough and the first portion of the sheath together defines a cavity for receiving the stent, and wherein when the first portion and the second portion of the sheath are separated from each other, the protection device is removable from the coiled tube.

Optionally, in the medical device, the protection device further comprises fasteners that are secured to an outer surface of the coiled tube or clamped onto an inner surface of the coiled tube by elastic deformation.

Optionally, in the medical device, the protection device further comprises a protective layer provided on an inner surface of the sheath.

In the protection device for stent and the medical device provided in the present invention, the protection device for stent mainly includes the sheath and the first and second grips. The sheath is configured to hold a stent, and the first grip is able to be driven to move toward the second grip so that the first portion of the sheath is caused to move away from the second portion thereof, allowing removal of the stent from the sheath. The protection device for stent according to the present invention can be operated by only one hand to cause the first grip to move toward the second grip, resulting in the separation of the sheath's first portion from the sheath's second portions. This easy operation results in a significant improvement in operating efficiency.

<FIG> do not represent embodiments of the invention.

In <FIG>, <NUM> denotes a protection device for stent; <NUM>, a sheath; 100a, a first portion; 100b, a second portion; <NUM>, an opening; <NUM>, a slot; <NUM>, a first grip; <NUM>, a second grip; and <NUM>, a cavity.

In <FIG> and <NUM>, <NUM> denotes a protection device for stent; <NUM>, sheath; 200a, a first portion; 200b, a second portion; <NUM>, a slit; <NUM>, a first grip; <NUM>, a second grip; <NUM>, a cavity; <NUM>, a protective layer; <NUM>, a connecting member; <NUM>, a first fastener; <NUM>, a second fastener; <NUM>, a coiled tube; and <NUM>, an engagement tough.

In <FIG>, <NUM> denotes a protection device for stent; <NUM>, a sheath; 300a, a frame; 300b, elastomer filler; 300c, a fastener; <NUM>, a slit; <NUM>, a first grip; <NUM>, a second grip; <NUM>, a cavity; <NUM>, a protective layer; <NUM>, a stent; and <NUM>, a balloon catheter.

The protection device for stent proposed herein will be described in greater detail below by way of particular examples with reference to the accompanying drawings. Features and advantages of the invention will be more apparent from the following detailed description, and from the appended claims. Note that the figures are provided in a very simplified form not necessarily drawn to scale, with the only intention to facilitate convenience and clarity in explaining the examples. In particular, as the figures tend to have distinct emphases, they are often drawn to different scales.

In this specification, when reference is made to a "stent", this term will refer to a squeezed stent. That is, a "squeezed stent" will be referred to as a "stent" hereinafter for short. The protection device for stent of the present invention can protect a squeezed stent while maintaining it to a diametrical dimension in favor of a delivery system.

The protection device for stent includes a sheath, a first grip and a second grip. The sheath is configured to hold a stent, and the first grip can be driven to move toward the second grip so that a first portion of the sheath is caused to move away from a second portion thereof, allowing removal of the stent from the sheath.

The first portion and/or the second portion include(s) a frame and elastomer filler that is filled in the frame and define a cavity for receiving the stent. The protection device for stent of the present invention will be better understood from the following description of a few specific examples.

Reference is now made to <FIG>, a structural schematic of a protection device for stent according to the present embodiment, and to <FIG>, a side view of the protection device for stent of <FIG>. As illustrated in <FIG>, the protection device for stent <NUM> includes a sheath <NUM>, a first grip <NUM> and a second grip <NUM>. The sheath <NUM> is configured to hold a stent and includes first and second portions connected to each other. The first grip <NUM> can be driven to move toward the second grip <NUM> so that the first portion of the sheath <NUM> is caused to move away from the second portion thereof, allowing removal of the stent from the sheath <NUM>. The first grip <NUM> is formed of an extension of the first portion of the sheath <NUM>, whilst the second grip <NUM> is formed of an extension of the second portion of the sheath <NUM>. The first and second portions are integral with each other at their respective sides away from the first and second grips, respectively. The first grip <NUM> defines an axially-extending opening <NUM>, through which the second grip <NUM> is inserted and opposes the first grip <NUM>. In another embodiment, the second grip <NUM> may define an axially-extending opening, through which the first grip <NUM> is inserted and opposes the second grip <NUM>.

In order to increase friction on the first and second grips <NUM>, <NUM> during use and obtain improved operational stability, a number of anti-slipping means are preferably provided on the first and second grips <NUM>, <NUM> so that some of them are arranged on a side of the first grip <NUM> facing away from the second grip <NUM>, and the rest on a side of the second grip <NUM> facing away from the first grip <NUM>.

With continued reference to <FIG>, in particular, the sheath <NUM> may define an axially-extending slot <NUM> having two edges opposing each other along a circumferential direction of the sheath <NUM> (and respectively forming an end of the first portion close to the first grip and an end of the second portion close to the second grip). The first and second grips <NUM>, <NUM> may be connected respectively to these edges, with one being inserted into the other, so that they bridge the slot and define (delimit), together with the sheath <NUM>, a cavity <NUM> that retrains the stent's resilience.

The cavity <NUM> delimited by the sheath <NUM>, the first grip <NUM> and the second grip <NUM> restrains the stent's resilience by providing radial compressive forces, and the bridging of the slot <NUM> by the first and second grips <NUM> that are inserted one into the other provides radial support for maintain a circular cross-section of the stent. This effectively prevents radial resilience of the stent so that, when the stent is squeezed and secured to a balloon in a delivery system, it can maintain a diametrical dimension favorable to the delivery system (i.e., a diameter as when it was squeezed) up until the time when the stent system is delivered to a target site within a body. In addition, in the protection device for stent <NUM> of this embodiment, in addition to being inserted one into the other to bridge the slot <NUM> and delimit the cavity <NUM> that restrains the stent's resilience together with the sheath <NUM>, the first and second grips <NUM>, <NUM> are also allowed to each have a significantly reduced width (perpendicular to an axis of the protection device <NUM>) so as to allow the protection device to be loaded in (i.e., accommodated within) another structure.

The sheath <NUM> and the first and second grips <NUM>, <NUM> may be formed by forging and cutting a metal sheet, or by molding a polymeric material. The metal sheet is preferably made of alloy(s) with good biocompatibility, such as at least one of a stainless steel, a nickel-titanium alloy and a magnesium alloy. The polymeric material is preferably a polymeric material with good biocompatibility containing, for example, at least one of PTFE, Pebax, polyethylene, polycarbonate, polyamide and nylon. The sheath <NUM> may appear as a hollow tube, and the stent is held therein in a squeezed state where its outer diameter is equal to an inner diameter of the sheath <NUM>. In addition, the sheath <NUM> may have a length that is greater than or equal to a length of the squeezed stent so that it is able to entirely cover an outer surface of the stent and apply a constraining force radially to the squeezed stent, thus better restraining the stent's radial resilience.

In order for better understanding the working principles of the protection device for stent according to the present invention, the operation of the protection device for stent <NUM> of this embodiment will be described below in detail with reference to <FIG>.

First of all, in step S11, external forces are exerted on the first and second grips <NUM>, <NUM> so that the first grip <NUM> moves toward the second grip <NUM>, causing the free ends of the first and second portions of the sheath <NUM> to move away from each other (manifested as an expansion of the slot <NUM> and a diametrical expansion of the cavity <NUM> that restrains the stent's resilience).

Next, in step S12, the stent is removed from the sheath <NUM>.

Specifically, for example, this can be accomplished by only one hand of an operator. The operator may press the first and second grips <NUM>, <NUM>, with the thumb and index finger, respectively, in the directions indicated by the arrows in the <FIG>. Under the pressure, the first grip <NUM> will move toward the second grip <NUM>, causing the free ends of the first and second portions of the sheath <NUM> to move away from each other. This is manifested as movements of the two ends of the slot <NUM> opposing each other in the circumferential direction of the sheath <NUM> in the directions opposite to those indicated by the arrows, which results in an expansion of the slot <NUM> and a diametrical expansion of the cavity <NUM> that restrains the stent's resilience, making it possible to release the stent from constraints of the cavity <NUM> and thus from the sheath <NUM> in a contactless and frictionless manner.

A protection device for stent according to a second embodiment is structurally different from that of Embodiment <NUM> in further including a connecting member, in addition to a sheath, a first grip and a second grip. The connecting member connects the first and second grips to each other. In this embodiment, the connecting member is a metal member.

Reference is now made to <FIG>, a schematic illustration of a first structural variant of the protection device for stent according to this embodiment. As shown in <FIG>, the sheath <NUM> is split by a slit <NUM> into a first portion 200a and a second portion 200b that are separable from each other. The sheath <NUM> appears as a hollow tube and has a length that is greater than or equal to a length of a squeezed stent load therein, so that it is able to entirely cover an outer surface of the stent and apply a constraining force radially to the squeezed stent, thus better restraining the stent's radial resilience. In this way, when the stent is squeezed and secured to a balloon in a delivery system, it can maintain a diametrical dimension favorable to the delivery system up until the time when the stent system is delivered to a target site within a body.

With continued reference to <FIG>, in the protection device for stent <NUM>, the connecting member <NUM> connecting the first and second grips <NUM>, <NUM> is preferably a spring tending to resist the pressure force that would cause opposing movements of the first and second grip <NUM>, <NUM> and maintain the connection between the first and second portions 200a, 200b. This can ensure the stability of the cavity <NUM> that restrains the stent's resilience. When the pressure force is greater than the resistance threshold of the spring, the first and second portions 200a, 200b will move away from each other, leading to a diametrical expansion of the cavity <NUM> that restrains the stent's resilience.

The connecting member <NUM> is not limited to being a spring, because it can be any one of multiple structures including, for example, a spring strip or a shaft, as in particular shown in <FIG>. Reference is now made to <FIG>, a schematic illustration of a second structural variant of the protection device for stent according to this embodiment, and to <FIG>, a side view of the protection device for stent of <FIG>. The protection device for stent <NUM> shown in <FIG> and <FIG> differs from that in <FIG> in the structure of the connecting member <NUM>. As shown in <FIG> and <FIG>, the connecting member <NUM> is a shaft such as a pin shaft. The first grip <NUM> is connected to the first portion 200a to form a first piece, and the second grip <NUM> is connected to the second portion 200b to form a second piece. The shaft extends through an overlap between the first and second pieces. In order for ensure robustness of the protection device, the protection device for stent <NUM> further includes a first fastener <NUM> and a second fastener <NUM>. The first fastener <NUM> is connected to the first grip <NUM>, while the second fastener <NUM> is connected to the second grip <NUM>. When the first fastener <NUM> engages the second fastener <NUM>, the first and second grips <NUM>, <NUM> are limited in position relative to each other, with the first and second portions 200a, 200b being connected together.

Reference is now made to <FIG>, a schematic illustration of a third structural variant of the protection device for stent according to this embodiment, and to <FIG>, a side view of the protection device for stent of <FIG>. The protection device for stent <NUM> shown in <FIG> and <FIG> differs from those in <FIG> and in <FIG> and <FIG> in the overall structure of the protection device and in the structure of the connecting member <NUM>. As shown in <FIG> and <FIG>, the connecting member <NUM> is a spring strip with ends disposed close to respective centers of the first and second grips. In this embodiment, the spring strip is curved and defines an opening in which the sheath <NUM> is secured. In particular, as shown in <FIG>, the opening has two edges fixedly connected respectively to the first and second portions 200a, 200b. The first and second portions 200a, 200b are axisymmetric, and the two edges of the opening are further fixedly connected respectively to the first and second grips <NUM>, <NUM>. The first and second grips <NUM>, <NUM> are axisymmetric. In this way, the spring strip provides a resistance force in response to the opposing movements of the first and second grip <NUM>, <NUM>, causing an expansion of the opening of the spring strip. As a result, the first and second portions 200a, 200b moves away from each other, and the cavity <NUM> that restrains the stent's resilience experiences a diametrical expansion. Preferably, the spring strip is C-shaped.

Reference is now made to <FIG>, a structural schematic of the protection device for stent according to this embodiment assembled with a stent and a balloon catheter. As shown in <FIG>, in order to avoid damage to a coating on the surface of the stent <NUM> during the removal of the stent from the sheath <NUM>, the protection device according to this embodiment may further include a protective layer <NUM> disposed on an inner surface of the sheath <NUM> (i.e., surrounding an outer surface of the stent <NUM>). The protective layer <NUM> can not only provide protection to the stent <NUM>, but also allows the sheath <NUM> to apply a higher preload to the stent <NUM>. Preferably, the sheath <NUM> is a metal sheath or a polymer sheath, with the first and second grips <NUM>, <NUM> being both metal grips, and with the protective layer <NUM> being a polymer film wrapping the outer surface of the stent and insulating it from the sheath.

Reference is now made to <FIG>, a schematic illustration of a fourth structural variant of the protection device for stent according to this embodiment. The protection device for stent of <FIG> differs from that of <FIG> in (i) omitting the connecting member, with the sheath providing the functions of the connecting member instead and (ii) differences in the structures of the first and second portions. As shown in <FIG>, the sheath <NUM> of the protection device for stent <NUM> is split by a slit <NUM> into first and second portions with respective ends separable from each other. The first and second portions are integral with each other at the respective other ends. That is, the slit <NUM> extends from an outer surface of the sheath <NUM> radially into the cavity <NUM>. The first and second portions include a frame 300a and elastomer filler 300b that is filled within the frame 300a and defines the cavity for receiving the stent. The first and second grips <NUM>, <NUM> are disposed on opposing sides of the frame 300a. As shown in <FIG>, in the process that the sheath <NUM> resists the pressure force on the first and second grips <NUM>, <NUM>, the sheath <NUM> will elastically deform, causing a diametrical expansion of the cavity <NUM> and thus allowing removal of the stent from the sheath <NUM>.

As shown in <FIG>, in order to avoid damage to a coating on the surface of the stent <NUM> during the removal of the stent from the sheath <NUM>, the protection device for stent <NUM> according to this embodiment may further include a protective layer <NUM> disposed on an inner surface of the sheath <NUM> (i.e., surrounding an outer surface of the stent <NUM>). The protective layer <NUM> can not only provide protection to the stent <NUM>, but also allows the sheath <NUM> to apply a higher preload to the stent <NUM>.

Referring to <FIG>, on the basis of the structure shown in <FIG>, the protection device for stent <NUM> may further include fasteners 300c enabling engagement with other components. Each fastener 300c can be structured as needed, and the present invention is not limited to any particular structure thereof.

Referring to <FIG>, <FIG> and <FIG>, in an embodiment, there is provided a medical device including a stent <NUM> squeezed within a balloon catheter <NUM>, a coiled tube <NUM> and any of the protection devices for stent as described in Embodiment <NUM> and <NUM>. The protection device for stent is coupled to the coiled tube <NUM>. In the case shown in <FIG>, the medical device includes the protection device for stent <NUM> shown in <FIG>.

With combined reference to <FIG>, the coiled tube <NUM> includes an engagement tough <NUM> configured to be received in the sheath <NUM> so that the coiled tube <NUM> defines the stent cavity <NUM> together with the first portion 200a of the sheath <NUM>. When the first and second portions 200a, 200b of the sheath are separated from each other, the protection device for stent <NUM> can be removed from the coiled tube <NUM>.

The engagement of the protection device for stent with the coiled tube is not limited to being accomplished by the structure shown in <FIG> in which the engagement tough <NUM> and the first portion 200a of the sheath <NUM> together delimits the stent cavity. Alternatively, a groove that can engage the engagement tough <NUM> (the groove may be complementary to the engagement tough in cross-sectional shape so that the coiled tube can be assembled with the sheath when the engagement tough is engaged in the groove) may be formed in the first or second portion so that the first and second portions together delimit the stent cavity.

Referring to <FIG>, the protection device for stent may further include fasteners 300c, which are fastened to an outer surface of the coiled tube or clamped onto an inner surface of the coiled tube by elastic deformation.

The embodiments disclosed herein are described in a progressive manner, with the description of each embodiment focusing on its differences from others. Reference can be made between the embodiments for their identical or similar parts. Since the medical device of Embodiment <NUM> employs a protection device for stent of Embodiment <NUM> or <NUM>, it is described relatively briefly, and reference can be made to the related description of Embodiment <NUM> or <NUM> for more details in Embodiment <NUM>. As the methods described in the embodiments correspond to the respective structures in the embodiments, they are described relatively briefly, and reference can be made to the related description of the structures for more details in the methods.

In summary, in the protection device for stent provided in the present invention, the protection device for stent mainly includes the sheath and the first and second grips. The sheath is configured to hold a stent, and the first grip is able to be driven to move toward the second grip so that the first portion of the sheath is caused to move away from the second portion thereof, allowing removal of the stent from the sheath. The protection device for stent can be operated by only one hand to cause the first grip to move toward the second grip, resulting in the separation of the sheath's first portion from the sheath's second portions. This easy operation results in a significant improvement in operating efficiency. Further, a diametrical expansion resulting from the opposing movements of the first and second grips allows the stent to be removed from the protection device without sliding contact between them. This can effectively avoid damage to the stent or its surface coating. Furthermore, the fasteners can provide stable support to the sheath for a long term, thus avoiding radial resilience of the stent due to deformation of the sheath during storage.

Claim 1:
A protection device (<NUM>) for stent, comprising a sheath (<NUM>, <NUM>, <NUM>), a first grip (<NUM>, <NUM>, <NUM>) and a second grip (<NUM>, <NUM>, <NUM>), the sheath (<NUM>, <NUM>, <NUM>) being configured to hold a stent, the first grip (<NUM>, <NUM>, <NUM>) is configured to be able to be driven to move toward the second grip (<NUM>, <NUM>, <NUM>) to cause a first portion (100a, 200a) of the sheath (<NUM>, <NUM>, <NUM>) to move away from a second portion (100b, 200b) thereof, so that the stent is allowed to be removed from the sheath (<NUM>, <NUM>, <NUM>);
wherein the first portion (100a, 200a) and the second portion (100b, 200b) form a frame (300a), and an elastomer filler (300b) is filled in the frame (300a) and defines a cavity (<NUM>) for receiving the stent.