Patent ID: 12220332

DETAILED DESCRIPTION OF THE EMBODIMENTS

Embodiments will now be described in detail with reference to the accompanying drawings for clearer understanding of the features, objects, and effects.

To facilitate the description, a lumen is described by taking a blood vessel as an example, which may be an aortic arch, or a thoracic aorta, or an abdominal aorta. Persons of ordinary skill in the art may appreciate that the use of a blood vessel for illustration is only for exemplary purpose, and is not a limitation. A solution of the embodiments is applicable to various human lumens, such as the lumen of the alimentary canal, etc. Such improvements and modifications based on the embodiments are all within the scope of the embodiments. In addition, in explaining the blood vessel, the direction may be defined according to the flow direction of blood, and the blood flow is defined as from the proximal end to the distal end. Unless otherwise specified, the radial support structure described refers to a closed waveform ring common in the art arranged along the axial direction of the membrane-covered stent.

As shown inFIG.5, an exemplary embodiments provides a luminal stent100, including a tubular body10and a skirt20sleeved outside the tubular body10.

The tubular body10is a tubular structure with an axial direction, which may serve as a new blood flow channel after being implanted in a blood vessel. The tubular body10includes at least a first radial support structure11and a first overlay membrane12covering the first radial support structure11. The first radial support structure11fits with the first overlay membrane12to form the side wall of the tubular body10.

The first radial support structure11may be made of various biocompatible materials, such as nickel-titanium, stainless steel, and the like. The first radial support structure11may include a plurality of turns of waveform rings in the axial direction, such as a plurality of turns of Z-shaped waves, M-shaped waves, or other structures that may be radially compressed to a small diameter; or may include a spirally wound structure; or may include a mesh structure. The first radial support structure11may be wound from a metal wire or cut from a metal tube. The first overlay membrane12is made of a polymer material with good biocompatibility, such as a PET membrane, a PTFE membrane, etc. The first overlay membrane12may cover on the first radial support structure11by sewing or hot melting.

Through the above-mentioned first radial support structure11, the tubular body10has a radial expansion capability, and may be compressed under an external force and may restore to and maintain its original shape by self-expansion or by mechanical expansion (for example, balloon inflation) after the external force is withdrawn, whereby after the tubular body10is implanted into the lumen, it may be fixed in the lumen by engaging against the wall of the lumen by its radial support force. It can be noted that, unless otherwise specified, it is the initial shape of the luminal stent after radial deployment that is described in this embodiment. Through the first overlay membrane12described above, the tubular body10may isolate a diseased area of a lumen. For example, it may isolate an arterial dissection or an aneurysm after being implanted into an arterial blood vessel.

The skirt20includes at least a second radial support structure21and a second overlay membrane22covering the second radial support structure21. The second radial support structure21and the second overlay membrane22of the skirt20may be a same or similar radial support structure and overlay membrane as those of the above-mentioned tubular body10, therefore, they will not be repeated here for the sake of brevity. With the second radial support structure21, the skirt20has radial expansion capability.

One end of the skirt20is a fixed end20a, and the fixed end20amay be sealedly connected to the outer surface of the tubular body10by sewing or hot melting. For example, the second overlay membrane22of the fixed end20amay be thermally fused with the first overlay membrane11of the tubular body10together to achieve the sealed connection. The other end of the skirt20is a free end20b, and the free end20bis radiated outwards, so that the skirt20forms an approximately conical structure, that is, the cross section of the skirt20gradually increases along the direction from the fixed end20ato the free end20b.

Referring toFIG.6, in a section passing through the central axis of the tubular body10, the ratio of the distance L between the fixed end20aand the free end20bon the same side of the central axis of the tubular body10to the vertical distance D between the two free ends20balong the radial direction of the skirt20is less than 1/2.

During the eversion of the skirt20, the free end20bturns around the fixed end20aon the same side in a direction away from the tubular body10, and the vertical distance h from the free end20bto the outer surface of the tubular body10increases continuously. When the line connecting the free end20bwith the fixed end20aon the same side is perpendicular to the central axis of the luminal stent, as shown by the dotted line inFIG.6, the vertical distance between the free end20b′ and the outer surface of the tubular body10reaches the maximum. At this time, the vertical distance between the two free ends20b′ in the radial direction of the skirt20is D′. It may be appreciated that, because the second radial support structure21and the second overlay membrane22are not ductile, the skirt20will not be elastically deformed. In case the vertical distance d between the two fixed ends20aalong the radial direction of the skirt20is constant, it is necessary to stretch the skirt20to gradually increase D to D′, or bend the skirt20so that the vertical distance h from the free end20bto the outer surface of the tubular body10does not increase, but stretching or bending the skirt20will damage the overlay membrane structure of the skirt20, leading to irreversible damage to the skirt20.

Referring also toFIG.7, when the distance L between the fixed end20aand the free end20bon the same side of the tubular body10is less than D/2, the two fixed ends20amay be compressed radially so that D′ is not greater than D, that is, flanging without stretching or bending the skirt20. The direction shown by the arrow inFIG.7is the direction in which the two fixed ends20aare compressed radially. The dotted line shows the schematic diagram of the luminal stent when the line connecting the free end20band the fixed end20aon the same side is perpendicular to the central axis of the luminal stent after the two fixed ends20aare compressed radially.

It may be seen from the above that by adjusting the ratio of L and D, the skirt20may evert without being stretched or bent when the two fixed ends20aare compressed radially.

Furthermore, the ratio of the vertical distance D between the two free ends20bin the radial direction of the skirt20to the vertical distance d between the two fixed ends20ain the radial direction of the skirt20is greater than or equal to 3/2. It can be noted that the vertical distance D between the two free ends20bin the radial direction of the skirt20and the vertical distance d between the two fixed ends20ain the radial direction of the skirt20are based on the initial shape after the radial expansion of the luminal stent.

Since the skirt20is mainly used to fill the gap between the tubular body10and the hole of the membrane-covered stent to prevent internal leakage, if the ratio of the vertical distance D between the two free ends20balong the radial direction of the skirt20to the vertical distance d between the two fixed ends20aalong the radial direction of the skirt20is too small, the skirt20may fail to completely fill the gap, leading to type III internal leakage.

In the manufacturing process of the skirt20, a mold rod is required to be sheathed on the tubular body10. If the included angle α between the connection line of the fixed end20aand the free end20bon the same side of the tubular body10and the center axis of the skirt20is too small, the included angle of the corresponding mold rod is also small, and the mold rod with a small included angle may not be easy to process. Therefore, to facilitate the processing, the included angle α between the connection line of the free end20band the fixed end20aon the same side of the tubular body10and the center axis of the skirt20is not less than 30°. It may be appreciated that, in a section passing through the central axis of the skirt20, the included angle α on both sides of the tubular body10may be the same or different.

In this embodiment, the tubular body10is shaped as a straight tube, and the skirt20is shaped as a frustum. In a section passing through the central axis of the skirt20, the contour line of the skirt20is a straight line, and the vertical distance d between the two fixed ends20aalong the radial direction of the skirt20is the outer diameter of the tubular body10. It may be appreciated that, in other embodiments, in a section passing through the central axis of the skirt20, the contour line of the skirt20may also be an arc, a mixed line segment of a straight line and a straight line, a combined line segment of a straight line and an arc, or other irregular line segments. As shown inFIG.8, in a section passing through the central axis of the skirt20, the contour line of the skirt20is arc-shaped. Alternatively, as shown inFIG.9, in a section passing through the central axis of the skirt20, the contour line of the skirt20is a mixed line segment of a straight line and a straight line.

As shown inFIG.10, the second radial support structure21includes at least one waveform ring210, and each waveform ring210is a closed ring-shaped structure including a plurality of proximal vertices211, a plurality of distal vertices212, and a support213connecting the adjacent proximal vertex211and the distal vertex212, and the proximal vertices211and the distal vertices213correspond to the peaks or troughs of the waveform, respectively. In this embodiment, the second radial support structure21includes one waveform ring210. The plurality of proximal vertices211of the waveform ring210are located in the same plane perpendicular to the central line of the skirt20. The plurality of distal vertices212are also located in the same plane perpendicular to the central axis of the skirt20. It may be appreciated that, in other embodiments, the second radial support structure21may further include a plurality of waveform rings210. The plurality of waveform rings210are sequentially arranged along the axial direction of the skirt20, preferably arranged in parallel intervals, or the a plurality of waveform rings210are connected to form a mesh structure.

The second radial support structure21may be distributed on a part of the skirt20, that is, along the center axis direction of the skirt20, and the maximum length of the two ends of the second radial support structure21is shorter than the length of the skirt20. The second radial support structure21may also be distributed over the entire skirt20, that is, along the center axis direction of the skirt20, and the maximum length of the two ends of the second radial support structure21is equal to the length of the skirt20. In this embodiment, the second radial support structure21is distributed over the entire skirt20. The end of the second radial support structure21close to the free end20bis flush with the free end20bof the skirt20. The end of the second radial support structure21close to the fixed end20ais flush with the fixed end10aof the skirt20.

Additionally, the end of the second radial support structure21close to the fixed end20ais rotatably connected to the first radial support structure11of the tubular body10. Due to the poor mechanical behavior of the overlay membrane, if the skirt20and the tubular body10are connected only by the overlay membrane, the skirt10is easily pulled or deformed when flanging. It may increase the connection strength between the skirt20and the tubular body10by connecting the second radial support structure21to the first radial support structure11, which in turn avoids the skirt10from being deformed or broken during the flanging, and also facilitates the eversion of the skirt. It may be appreciated that the embodiments do not limit the manner of the rotatable connection between the second radial support structure21and the first radial support structure11. As shown inFIG.11, at least one wave peak (or wave trough) of the second radial support structure21and at least one wave trough or (wave peak) of the first radial support structure11are hooked to each other. Alternatively, as shown inFIG.12, at least one wave peak (or wave trough) of the second radial support structure21and at least one wave trough or (wave peak) of the first radial support structure11are connected through a connection ring30, which may be formed by winding with a flexible wire, or a metal ring made of a biocompatible material, such as nickel titanium, stainless steel and other materials. In this embodiment, all the peaks (or troughs) of the side of the second radial support structure21close to the fixed end20aare connected to the first radial support structure11. It may be appreciated that, in other embodiments, a part of the peaks (or troughs) of the side of the second radial support structure21close to the fixed end20amay be connected to the first radial support structure11.

With reference toFIGS.10and13, the waveform ring210is approximately a frustum structure, and the waveform included angle a1of the side of the waveform ring210close to the fixed end20ais greater than the waveform included angle a2of the side of the waveform ring210distant from the fixed end20a. That is, the waveform angle a1corresponding to the proximal vertex211is greater than the waveform angle a2corresponding to the distal vertex212. The waveform included angle refers to the included angle between the supports104connected on both sides of the same proximal vertex102or distal vertex103.

It may be appreciated that the greater the waveform included angle of the waveform ring210, the greater the radial force required to squeeze the waveform ring210, and the waveform ring210is prone to plastic deformation or rupture during the extrusion, and if the waveform included angle is too small, it is not conducive to processing. Referring also toFIG.14, when the fixed end20aof the skirt20is compressed in the radial direction, the plurality of proximal vertices211of the waveform ring210converge toward one side of the central axis of the skirt20. The waveform included angle a2corresponding to the distal vertex212of the waveform ring210gradually decreases, and tends to 0°. In order to facilitate the compression of the fixed end20aof the skirt20in the radial direction, the waveform included angle a2corresponding to the distal vertex212of the waveform ring210is about 10°-30°.

It may also be appreciated that if the wire diameter of the waveform ring210is too small, it will affect the radial support force of the second radial support structure21, but the greater the wire diameter of the waveform ring210, the greater the radial force required for compressing the waveform ring210, and the waveform ring210is prone to plastic deformation or fracture during the extrusion process. Therefore, the wire diameter of the waveform ring210is in a range of 0.05 mm to 0.15 mm, and e.g. ranging from 0.07 mm to 0.13 mm.

As shown inFIGS.15to16, a second exemplary embodiment provides a luminal stent, which is different from the first embodiment in the structure of the second radial support structure21.

As shown inFIG.16, the second radial support structure21includes a waveform ring210rotatably connected to the first radial support structure11. For example, the waveform ring210is a closed ring structure, which includes at least one first proximal vertex211a, a plurality of second proximal vertices211b, a plurality of distal vertices212, and a support213connecting the adjacent first proximal vertex211aand the distal vertex212or the adjacent second proximal vertex211band the distal vertex212. The first proximal vertex211aand the second proximal vertex211bcorrespond to the peaks of the waveform, and the distal vertices212correspond to the troughs of the waveform.

The first proximal vertex211aextends to the fixed end10aof the skirt20and is rotatably connected to the first radial support structure11. By taking any one of the plurality of distal vertices212as the reference distal vertex, and in the direction of the central axis of the skirt20, the distance between the first proximal vertex211aand the reference distal vertex is greater than the distance between the second proximal vertex211band the reference distal vertex, and the included angle connected between the supports104to both sides of the first proximal vertex211ais smaller than the included angle between the supports104connected to both sides of the second proximal vertex211b.

It may be appreciated that when the wave height of the waveform ring210is constant, the greater the waveform included angle is, the greater the radial support force of the waveform ring210is, but if the waveform included angle is too large, it is not conducive to sheathing. Similarly, when the included angle of the wave ring210is constant, the smaller the wave height is, the larger the radial support force corresponding to the wave ring210is, but if the wave height is too small, it is not possible to maintain the roundness of the skirt20, hindering the sealing effect of the skirt20. Therefore, an embodiment may increase the radial support force of the skirt20by providing a plurality of second proximal vertices211bwith relatively small wave heights and relatively large waveform included angles, while increasing the connection strength between the skirt10and the tubular body20by connecting the first proximal vertex211aand the first support structure11. For example, the ratio of the distance between the first proximal vertex211aand the reference distal vertex to the distance between the second proximal vertex211band the reference distal vertex is 0.3 to 0.8, and the included angle between supports213on both sides of the second proximal vertex211bis 30° to 150°.

In this embodiment, the a plurality of distal vertices212of the waveform ring210are located in the same plane perpendicular to the central axis of the skirt20and are flush with the free end20bof the skirt20, and the first proximal vertex211aextends to the fixed end10aof the skirt20, and is rotatably connected to the first radial support structure11.

It may be appreciated that the embodiments do not limit the number of the first proximal vertex211a, and the first proximal vertex211amay include one or more vertices. When the first proximal vertex211aincludes a plurality of vertices, the plurality of the first proximal vertices211aare uniformly distributed along the circumferential direction of the skirt21. For example, the number of the first proximal vertices211ais less than or equal to the number of the second proximal vertices211bto increase the radial support force of the skirt20.

It may also be appreciated that, in other embodiments, the second radial support structure21may further include other waveform ring structures, spirally wound structures or mesh structures.

The various features of the above-mentioned embodiments may be combined in any way, and in order to simplify the description, not all possible combinations of the features of the above-mentioned embodiments are described. However, as long as there is no conflict between these features, they should be considered to be within the scope of the description.

The embodiments described above represent only a few embodiments of the present disclosure, but should not be construed to limit the scope of the present disclosure. It should be noted that several variations and modifications may be made by persons of ordinary skill in the art without departing from the spirit of the present disclosure.