Stent grafts and kits

Abstract

The present invention relates to a stent graft comprising: a hollow stent graft body having a lumen extending from one end of the stent graft body to a respective other end of the stent graft body; an expandable reservoir disposed on an interior of the stent graft body, the expandable reservoir being covered on a side of the expandable reservoir facing the lumen with a separation layer, the expandable reservoir being arranged to inflate when exposed to blood, the separation layer being arranged to prevent the expandable reservoir from being exposed to blood flowing through the lumen; the separation layer being arranged such that it can selectively expose the expandable reservoir to blood to inflate the expandable reservoir.

Description

Technical Field

[0001] The present invention relates to stent grafts that can be used as transjugular intrahepatic portosystemic shunts (TIPS) and kits containing such stent grafts. Background Technology

[0002] Portal hypertension is an increase in pressure in the venous vascular system of the digestive organs, which carries venous blood back through the liver and eventually back to the heart, but is obstructed due to liver disease such as cirrhosis. If left untreated, it often leads to intestinal bleeding or potentially life-threatening esophageal bleeding. Other complications may include the formation of excessively dilated veins (“varicose veins”), which can lead to sudden bleeding and death, or ascites with peritoneal effusion.

[0003] Transjugular intrahepatic portal shunt (TIPS) is used to address portal hypertension and its complications. A shunt made from a TIPS stent graft (i.e., a covered stent) extends through an artificial channel created within the liver and redirects venous blood from the portal vein to the hepatic vein, thereby reducing the pressure gradient throughout the liver.

[0004] However, after TIPS placement, 20% to 30% of patients develop hepatic encephalopathy due to excessive venous flow bypassing the liver via the shunt. This is because a large amount of blood bypasses the liver while only a small portion is filtered, resulting in a large amount of unfiltered blood and toxic molecules entering the brain. The resulting hepatic encephalopathy is accompanied by neuropsychiatric abnormalities characterized by personality changes, intellectual impairment, and decreased level of consciousness.

[0005] Furthermore, patient survival rates are very low. Hepatic encephalopathy leads to hospitalization and is associated with a one-year survival rate of approximately 42% and a three-year survival rate of approximately 23%. Given that hepatic encephalopathy is caused by excessive blood flow through the TIPS, there is a need for a TIPS whose diameter can be reduced after placement.

[0006] Commercially available TIPS stent grafts can be increased in diameter from an initial size of approximately 8 mm to approximately 10 mm to optimize portal vein pressure at placement. However, not all devices are capable of adjusting their diameter post-placement; in particular, currently available devices cannot limit their diameter after placement.

[0007] Furthermore, it is known in the medical community that TIPS shunts can increase in diameter over time, allowing for subsequent increases in blood flow. This can also lead to or exacerbate hepatic encephalopathy.

[0008] Therefore, there is a need for a TIPS scaffold graft whose diameter can be reduced after placement. Similarly, in other cases, scaffold grafts with reduced diameters are desirable. Summary of the Invention

[0009] The present invention aims to solve the above-mentioned problems and to provide a scaffold graft, particularly a TIPS scaffold graft, which can reduce its diameter after placement.

[0010] According to one embodiment, a stent graft suitable for TIPS surgery comprises a hollow stent graft body formed by a covered stent. The stent may be a self-expanding stent and may be made, for example, of a nickel-titanium alloy. The stent is covered by a suitable covering material (e.g., expanded polytetrafluoroethylene (“ePTFE”)) to form a hollow tube. In some embodiments, the stent of the TIPS stent graft is exposed (i.e., no covering material covers the stent). This uncovered portion can be used to anchor the TIPS stent graft in the portal vein.

[0011] The scaffold graft body includes a lumen extending from one longitudinal end of the scaffold graft body to a corresponding other longitudinal end of the scaffold graft body. The lumen is designed to allow fluid to flow from one end of the scaffold graft body to the corresponding other end of the scaffold graft body.

[0012] According to one aspect of the invention, an expandable reservoir is disposed inside the scaffold graft body. That is, the expandable reservoir is positioned facing the lumen. A separation layer is provided on the lumen-facing side of the expandable reservoir to separate the expandable reservoir from any fluid flowing through the lumen. The expandable reservoir is configured to expand upon exposure to blood. This is likely because the expandable reservoir contains an osmotically active substance, which should also be biocompatible. For example, sugar molecules of appropriate size used in dialysis (i.e., sugars with molecules significantly larger than water molecules) can be used as the osmotically active substance.

[0013] The separation layer is designed to prevent the expandable reservoir from being exposed to the blood flowing through the lumen. That is, it is this separation layer that prevents the expandable reservoir from swelling upon exposure to blood. This separation layer should be impermeable and insoluble in blood, so that the expandable reservoir will not be exposed to the blood unless required by the clinician.

[0014] The separation layer is configured to selectively expose the expandable reservoir to the blood, causing it to expand. When the separation layer exposes the expandable reservoir to the blood, blood components such as plasma or water seep into the reservoir, causing it to expand. This, in turn, reduces the cross-sectional area of ​​the lumen. Therefore, the stent graft can reduce its inner diameter after placement.

[0015] In some embodiments, a semi-permeable membrane is present between the expandable reservoir and the separator, wherein the membrane is made of a different material than the expandable reservoir. This membrane can be made of, for example, polysulfone, polyethersulfone, polyarylethersulfone, polyamide, polyvinylpyrrolidone, polycarbonate, polyacrylonitrile, or cellulose acetate, or modified cellulose, having pore sizes that allow water molecules to pass through but not permeable active substance molecules. This semi-permeable membrane allows water molecules to pass through but not sugars or other larger molecules. This semi-permeable membrane effectively retains the material of the expandable reservoir, ensuring that the material of permeable substances, such as those from the expandable reservoir, remains close to the wall of the scaffold implant. Therefore, the semi-permeable membrane ensures that the expandable reservoir maintains its shape.

[0016] In some embodiments, the release layer is configured to expose the expandable reservoir to the bloodstream when exposed to light of a predetermined wavelength. This exposure is facilitated, particularly by using a release layer that degrades upon exposure to light of a predetermined wavelength, i.e., by introducing a conduit containing an optical fiber conducting light of that wavelength into the placed scaffold graft, and then irradiating the release layer with appropriate light through the fiber. This release layer can be made of an amphiphilic copolymer that degrades upon exposure to light with wavelengths from 500 nm to 540 nm. Suitable materials include homopolymers and block copolymers of polyacrylates, polytriazines, and polyketides. For example, vinyl ketone-based block polymer films synthesized from polystyrene are photodegradable at a wavelength of 366 nm, while PEGMA polymer brush substrates are photodegradable at a wavelength of 400 nm. For further details, please see G. Pasparakis et al., “Photodegradable Polymers for Biotechnological Applications”, Macromol. Rapid Commun. 2012, 33, 183-198.

[0017] In some embodiments, the release layer is configured to become permeable to blood when exposed to one or more suitable chemicals. This stent graft can be readily implanted and the release layer can be readily dissolved (i.e., simply by exposing the release layer to an appropriate medication). For example, a catheter coated with these medications can be introduced into the patient's vascular system, or alternatively, these medications can be injected into the patient's vascular system without relying on a catheter.

[0018] In one embodiment, the expandable reservoir is formed as a ring surrounding the lumen. As the expandable reservoir expands, this results in a uniform reduction in diameter.

[0019] In some embodiments, the scaffold graft includes multiple independent expandable reservoirs positioned at different axial locations within the scaffold graft body. This configuration provides greater design flexibility and allows for the expansion of only some reservoirs, rather than all, if needed. This also provides greater flexibility in reducing the cross-sectional diameter of the scaffold graft.

[0020] According to another aspect of the invention, the present invention relates to a component kit comprising a catheter and a stent implant as defined above, the catheter being configured to expose an expandable reservoir to blood through a separation layer, thereby causing the expandable reservoir to expand.

[0021] In some embodiments, the component kit includes a stent graft with a dissociation layer and a catheter containing an optical fiber. The dissociation layer is configured to expose an expandable reservoir to blood when exposed to light of a predetermined wavelength. The optical fiber is configured to conduct light from the proximal end of the catheter to the distal end, and then exit the catheter, i.e., the light exits from the distal end. The component kit also includes a light source configured to emit light of a predetermined wavelength capable of causing the dissociation layer to decompose. If desired, using such a component kit allows for easy reduction of the stent graft diameter, even post-implantation.

[0022] In some embodiments, the component kit includes a stent graft with a separation layer and a catheter configured to release one or more suitable chemicals. By releasing such chemicals, the separation layer can be broken down, thereby becoming permeable to at least some blood components so that the expandable reservoir can expand. Attached Figure Description

[0023] Figure 1 schematically shows a cross-section of a TIPS scaffold graft according to a first embodiment of the present invention.

[0024] Figure 2 illustrates the use of the scaffold graft according to an embodiment.

[0025] Figure 3 A scaffold graft of an embodiment of the present invention in an expanded state is shown. Detailed Implementation

[0026] Figure 1a The diagram shows a cross-sectional view of a TIPS scaffold graft 10 according to the present invention. Although not shown, one longitudinal end of the scaffold graft 10 has a bare scaffold, i.e., this end does not have the covering material of the scaffold that forms the base of the scaffold graft 10.

[0027] The scaffold graft 10 includes a scaffold graft body 12 having a hollow tube shape. The scaffold graft body 12 (i.e., the body of the TIPS scaffold) surrounds a lumen 13 through which fluid can flow through the scaffold graft 10. Figure 1b As shown in more detail in [the diagram], inside the scaffold graft body 12, an expandable reservoir 14 is provided, first covered by a semi-permeable membrane 15 and then by a separation layer 16. The expandable reservoir 14 contains a permeable active material. The separation layer 16 is permeable to blood or some components of blood, but does not allow the material of the expandable reservoir 14 to pass through, thus holding the material in place. The semi-permeable membrane 15 is permeable to blood or at least some components of blood, but impermeable to the material of the expandable reservoir 14. Therefore, when the separation layer 16 is made permeable to blood, the expandable reservoir 14 will expand.

[0028] like Figure 1a ), Figure 1b The stent graft 10 shown is implanted into the patient. If it is desired to further restrict the diameter of the TIPS stent graft 10 at some point after placement, it can be performed... Figure 2a ), Figure 2b The procedure is shown in the diagram. A catheter 18 containing an optical fiber (not shown) is introduced into the patient's vascular system. Through this optical fiber, light 20 (e.g., ultraviolet light) can be irradiated onto the surface of the separation layer 16 to break it down, while the semi-permeable membrane 15 remains unaffected by light. Thus, the expandable reservoir 14 is exposed to the blood flowing through the lumen 13.

[0029] like Figure 3 As shown, due to the fluid present in the blood, the expandable reservoir 14 expands (e.g., Figure 3 (As shown). This expansion reduces the volume of blood available for flow in the lumen 13. Therefore, the stent graft 10 can reduce its inner diameter if needed.

[0030] Although this embodiment describes the separation layer 16 as being photopermeable, it can also be made permeable by exposing it to a suitable drug. Furthermore, it is conceivable to implement a mechanism that mechanically ruptures the separation layer 16, for example, by inserting a suture that can be pulled out, tearing the separation layer 16 upon extraction. If a separation layer capable of becoming permeable through a chemical reaction is desired, a catheter with a PTA balloon coated with a suitable chemical substance can be used. Once the balloon has been placed within the stent graft, it can be inflated to contact the separation layer 16. Through this contact, the separation layer 16 becomes permeable, allowing the expandable reservoir to expand.

Claims

1. Scaffold grafts (10), including: The hollow scaffold graft body (12) has a lumen (13) extending from one end of the scaffold graft body to the corresponding other end of the scaffold graft body. An expandable reservoir (14) is disposed inside the scaffold graft body (12). A separation layer (16) covers the side of the expandable reservoir (14) facing the lumen. The expandable reservoir (14) is configured to expand upon exposure to blood, and the separation layer (16) is configured to prevent the expandable reservoir (14) from being exposed to blood flowing through the lumen. The separation layer (16) is arranged such that it can selectively expose the expandable reservoir (14) to the blood, so that the expandable reservoir (14) expands radially inward to reduce the inner diameter of the lumen (13).

2. The scaffold graft according to claim 1, further comprising a semipermeable membrane (15) between the expandable reservoir (14) and the separation layer (16).

3. The scaffold graft according to claim 1 or 2, wherein the separation layer (16) is configured to expose the expandable reservoir to blood when exposed to light (20) of a preset wavelength.

4. The scaffold graft according to claim 1 or 2, wherein the separation layer (16) is configured to become permeable to blood when exposed to one or more chemicals.

5. The scaffold graft according to claim 1 or 2, wherein the expandable reservoir (14) has an annular shape surrounding the lumen.

6. The scaffold graft according to claim 1 or 2, wherein the scaffold graft (10) includes a plurality of expandable reservoirs (14) disposed at different axial positions within the scaffold graft body.

7. A component kit comprising a catheter (18) and a stent graft (10) according to any one of claims 1 to 6, the catheter being configured such that a separation layer (16) exposes an expandable reservoir (14) to blood, thereby allowing the expandable reservoir to expand.

8. The component kit of claim 7, wherein when the component kit includes the stent graft of claim 3, the conduit includes an optical fiber configured to conduct light (20) from the proximal end of the conduit to the distal end of the conduit and exit the conduit, the component kit further includes a light source configured to emit light of a predetermined wavelength, and the optical fiber configured to transmit light to the distal end of the conduit.

9. The component kit of claim 7, wherein when the component kit includes the stent graft of claim 4, the catheter is configured to release one or more suitable chemical substances selected such that the separation layer (16) is permeable to allow the expandable reservoir to expand due to exposure to blood.

10. A scaffold graft, comprising: A hollow scaffold graft body having a lumen extending from a first end of the scaffold graft body to a second end of the scaffold graft body. An expandable reservoir, disposed inside the stent graft body, is designed to expand when exposed to blood, but a separation layer is provided on the lumen-facing side of the expandable reservoir to prevent exposure of the expandable reservoir to blood flowing through the lumen. The separation layer is configured to selectively expose the expandable reservoir to blood to cause the expandable reservoir to expand radially inward to reduce the inner diameter of the lumen.

11. The scaffold graft of claim 10, further comprising a semi-permeable membrane between the expandable reservoir and the separation layer.

12. The scaffold graft of claim 11, wherein the semipermeable membrane is permeable to blood or at least some components of blood, but impermeable to the material of the expandable reservoir.

13. The scaffold graft according to claim 10, 11, or 12, characterized in that, The separation layer is configured to expose the expandable reservoir to blood when exposed to light of a preset wavelength.

14. The scaffold graft according to claim 10, 11, or 12, characterized in that, The separation layer is configured to become permeable to blood when exposed to one or more chemicals.

15. The scaffold graft according to claim 10, 11, or 12, characterized in that, The expandable reservoir has an annular shape surrounding the lumen.

16. The scaffold graft according to claim 10, 11 or 12, characterized in that, The expandable storage unit includes multiple independent expandable storage units located at different axial positions inside the scaffold graft body.

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