TIPS stent grafts and kits

Abstract

The present invention relates to a TIPS stent-graft comprising a tubular member having a lumen extending therethrough, the tubular member comprising a balloon-inflatable central section and first and second self-expanding sections sandwiching the central section, the lumen extending through the first section, the central section and the second section, the stent-graft being selectively collapsible of the central section.

Description

Technical Field

[0001] This invention relates to stent grafts used in transjugular intrahepatic portosystemic shunt (TIPS) and kits including TIPS stent grafts. Background Technology

[0002] Portal hypertension is an increase in pressure in the venous vascular system of the digestive organs, which allows venous blood to return through the liver and eventually back to the heart. However, this system can become blocked due to liver diseases such as cirrhosis.

[0003] Transjugular intrahepatic portosystemic shunt (TIPS) is used to address portal hypertension and its complications. A shunt, made from a TIPS stent graft (i.e., a covered stent), redirects venous blood from the portal vein to the hepatic veins, reducing the pressure gradient across the liver. 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, resulting in a smaller proportion of filtered blood, allowing a large amount of unfiltered blood and toxic molecules to enter the brain. The resulting hepatic encephalopathy is accompanied by neuropsychiatric abnormalities characterized by personality changes, intellectual impairment, and decreased level of consciousness.

[0004] Furthermore, patient survival rates are poor. Hepatic encephalopathy leads to hospitalization and is associated with a one-year survival rate of approximately 42% and a three-year survival rate of 23%. Given that hepatic encephalopathy is caused by excessive blood flow through the TIPS, there is a need for a TIPS that can reduce its post-placement diameter.

[0005] On the other hand, if there is not enough blood to bypass the liver and portal hypertension is not adequately treated, it is sometimes necessary to increase the diameter of the TIPS shunt after placement.

[0006] Commercially available TIPS stent grafts can be adjusted from an initial diameter of approximately 8 mm to approximately 10 mm to optimize portal vein pressure during placement. However, not all devices are capable of adjusting their diameter after placement, and in particular, there is no limitation on their diameter.

[0007] Therefore, there is a need for a TIPS scaffold graft that can increase its diameter after placement and can treat or prevent hepatic encephalopathy. Summary of the Invention

[0008] The present invention was made in view of the above considerations, and its purpose is to solve the aforementioned problems.

[0009] The present invention is defined by the TIPS scaffold graft according to claim 1 and the kit according to claim 14. Preferred embodiments are defined in the dependent claims.

[0010] This invention relates to a TIPS stent graft. This stent graft is a covered stent, typically having an uncovered end formed by an exposed stent located beneath the stent graft at one longitudinal end, for anchoring it within the patient's portal vein.

[0011] A TIPS stent graft includes a tubular component having a lumen extending therethrough. This lumen allows blood to flow from one longitudinal end of the TIPS stent graft to a corresponding longitudinal end.

[0012] The tubular component includes a balloon-inflatable central segment and a first self-inflating segment and a second self-inflating segment. The first and second self-inflating segments sandwich the central segment—that is, when moving along the longitudinal axis of the stent graft, the self-inflating segment is present first, followed by the balloon-inflatable segment, and then the corresponding second self-inflating segment. The self-inflating segment is one that, upon exposure to the patient's blood, will reach body temperature (i.e., approximately 37°C) and thus inflate without being forced to inflate by, for example, an inflatable balloon. In contrast, the balloon-inflatable central segment does not have this capability and does not inflate simply by reaching body temperature. A percutaneous transluminal angioplasty (PTA) balloon is being considered as the balloon for inflating the central segment.

[0013] The scaffold graft is arranged to selectively and reversibly reduce its cross-sectional diameter by restricting its central segment. That is, a means is provided to selectively give the central segment a narrower diameter. In other words, the scaffold graft includes means that can be used to restrict the central segment, thereby reducing the cross-sectional area of ​​the scaffold graft available for blood flow. Therefore, the scaffold graft according to the invention can prevent or treat hepatic encephalopathy by restricting its cross-sectional area. This reduces blood flow through the TIPS scaffold graft, which in turn increases blood flow through the liver. Since this blood will be filtered by the liver, the amount of unfiltered blood and toxic components reaching the brain are reduced, thereby preventing or improving hepatic encephalopathy.

[0014] Using the TIPS scaffold graft of the present invention, it is preferable that the central segment of the scaffold graft is expanded by, for example, placing a balloon catheter within the central segment and subsequently (via the balloon catheter or by some other means) expanding the scaffold graft. This allows for bidirectional adjustment (i.e., the TIPS scaffold graft can be expanded and contracted if desired), which can be performed multiple times as needed to adjust the pressure differential or flow rate throughout the scaffold graft.

[0015] Preferably, if the central segment comprises a shape memory alloy having a transition temperature higher than body temperature, the central segment is configured to exhibit a configuration that, when heated above its transition temperature, is more contracted in its expanded state than the first and second segments. For example, as a stent in a stent graft used in the present invention, a stent with a central segment having a higher transition temperature than the adjacent segments can be used. Therefore, a TIPS stent graft with a bidirectionally adjustable diameter can be provided through a very simple design. Thus, when the central segment is heated to a sufficiently high temperature, the TIPS stent graft will exhibit a narrower configuration. Preferably, the transition temperature of the central segment is such that heating the central segment to this temperature for a short period of time will not cause harm to the patient. The actual temperature will preferably be greater than or equal to 45°C, and more preferably between 45°C and 60°C. A temperature of approximately 60°C for a short period of time will not cause excessive stress to the patient's body. The central segment can be heated by introducing a catheter (e.g., an ablation catheter) into the central segment and then heating the catheter. This method appears to be the most practical and easy to implement.

[0016] Alternatively or additionally, it is preferable to have a separate shrinkage device for shrinking the central section. By having such a separate device, a simpler support design can be used since the shrinkage capability does not need to be incorporated into the support itself.

[0017] Preferably, the shrinkage device is a collar that wraps around the central segment. The collar is arranged to selectively reduce its inner diameter, thereby shrinking the central segment. Compared to cases where only a portion of the circumference is restricted, shrinkage occurs over the entire circumference of the central segment with the collar wrapping around it. This avoids unevenness in the shrinkage area.

[0018] Preferably, the collar is arranged to selectively reduce its inner diameter when heat is applied. Applying heat to the implanted scaffold graft is relatively easy, for example, by using induction heating (e.g., via an MRI device) or by guiding current through it. In both cases, current loss within the collar heats it up, which in turn restricts the central segment. Once the collar cools back to body temperature, it remains in a contracted configuration. The collar can also be actuated by applying a transient heat pulse (e.g., via a heating conduit introduced into the scaffold graft). Such a collar can be actuated more easily.

[0019] Preferably, the collar comprises metal. This metal can be easily heated by conducting electricity therein or by induction heating.

[0020] Preferably, the collar is arranged to heat up when electrical energy is applied, thereby reducing its inner diameter. That is, it heats up due to the resistance of the material used to make the collar or the materials contained within the collar. This heating then causes the collar to shrink, which reduces the cross-sectional area of ​​the scaffold graft. To supply electrical energy, the scaffold graft includes two or more electrodes to supply energy to the collar. By arranging the electrodes in this way, energy supply is relatively easy.

[0021] In this case, it is preferable that the electrodes are formed on the inner side of the scaffold graft. With such a scaffold graft, a catheter with electrodes on the outer side can be introduced after the scaffold graft is implanted, and these electrodes can be brought into contact with the electrodes of the scaffold graft. Energy can then be supplied to the scaffold graft through the catheter, thereby causing the scaffold graft to contract.

[0022] In this configuration, it is further preferred that the electrodes comprise a first electrode and a second electrode. The first electrode is disposed on a first self-expanding section, while the second electrode is disposed on a second self-expanding section. With this arrangement, the first and second electrodes are spaced apart from each other by the central section. This makes it easier for the catheter to contact them compared to a configuration where they are more closely spaced.

[0023] Preferably, the ring is formed into a cylindrical body. The cylindrical body provides a uniform and substantially constant force during contraction.

[0024] An alternative preferred method is to use a coil as a loop. This coil can be easily manufactured because it can be simply made from wire wound around a central section.

[0025] Preferably, the collar comprises a shape memory alloy. This shape memory alloy undergoes a shape change when heated above a specific transition temperature, wherein this shape change can be selected to cause the central segment of the stent implant to shrink. The shape change of this shape memory alloy (e.g., nitinol) is well characterized. Therefore, the resulting change in diameter is highly predictable.

[0026] Preferably, the shape memory alloy has a higher transition temperature than the first and second segments (which are typically also made of shape memory alloy to achieve their self-expansion capability). In this way, when the scaffold graft is implanted, the first and second segments will naturally expand, thereby positioning the scaffold graft within the body. However, the collar, due to its higher transition temperature, does not necessarily undergo such a transition. In this respect, it is preferred that the transition temperature of the collar's shape memory alloy is above body temperature, but not so high as to cause significant harm to the body if heated to that temperature for a short period (e.g., above 45°C or preferably between 45°C and 60°C). By heating the scaffold to this temperature, it can be contracted when needed without accidentally contracting it during implantation.

[0027] Another aspect of the invention is a kit comprising a TIPS stent graft as defined in any one of claims 7 to 9, and a catheter arranged for supplying electrical energy to electrodes from outside the stent graft, for example, from a power source outside the patient's body. In this manner, the catheter can be placed within the implanted stent graft and then retracted. Attached Figure Description

[0028] Figure 1 A TIPS scaffold graft according to a first embodiment of the present invention is shown.

[0029] Figure 2 A TIPS scaffold graft according to a second embodiment of the present invention is shown.

[0030] Figure 3 It shows Figure 2 A magnified view of the TIPS scaffold graft in the configuration in use.

[0031] Figure 4 A TIPS scaffold graft according to a third embodiment is shown. Detailed Implementation

[0032] Figure 1 The construction of a TIPS stent graft according to a first embodiment of the present invention is illustrated schematically. The stent graft 10 includes a first self-expanding segment 12 made of bare nitinol. This segment 12 can be placed in the patient's portal vein and is configured to remain at its intended size at temperatures above 20°C.

[0033] The central segment 14 is an ePTFE-coated nickel-titanium segment with a transformation temperature above 37°C (e.g., 50°C). This segment has a planned small nominal diameter of 6 mm or less at body temperature. At this temperature, the material of the support used in the central segment 14 (at least predominantly) is in the martensitic state. In this configuration, it is malleable and not permanently set. If this central segment 14 is raised to a temperature higher than its transformation temperature, the central segment will revert to its original small diameter.

[0034] The second segment 16 is an ePTFE-covered, self-expanding nitinol segment that is at its planned size at temperatures above 20°C (e.g., body temperature). Therefore, at body temperature, this second segment expands to a larger diameter.

[0035] When the stent graft 10 is placed in the liver channel already created for the TIPS procedure, the first segment 12 and the second segment 16 expand to their planned full diameter. In the case of the first self-expanding segment 12, this helps to position the stent graft and anchor it in the portal vein. In the case of segment 16, this helps to ensure that there is no flow restriction in that segment and may also help to position and anchor it.

[0036] The physician will then use a balloon to inflate the central segment 14 to its intended diameter (typically 8-10 mm). This will be larger than its nominal diameter of 6 mm or less. The material will remain in this inflated shape without damage, as long as the liver tissue does not cause the scaffold to collapse. If the pressure balance is acceptable in this configuration, no further steps are required.

[0037] If the physician later needs to reduce the flow through the stent graft 10 (due to hepatic encephalopathy or other reasons), he simply needs to raise the temperature of the central segment 14 of the stent above the transition temperature. This can be achieved by inserting a heater via a catheter, by applying voltage to the stent, or by any other method such as induction heating to raise the local temperature to, for example, 50°C for a short period of time. This can also be done using an MRI device or other non-invasive methods of heating the stent graft.

[0038] When the temperature of the stent rises above the transition temperature of the central segment 14, the material of the central segment 14 will reset to its pre-planned small diameter, which will reduce the flow through the stent graft 10. If the default setting of the cross-sectional diameter of the stent graft 10 achieved as a result is acceptable, no further action is required. On the other hand, if the physician needs to reopen the central segment 14 to a larger diameter, he can do so by cooling the central segment 14 to body temperature and re-inflating it to its desired size using a balloon.

[0039] This effectively allows for the initial placement of a scaffold graft with a diameter of 9 or 10 mm. If the scaffold is too large, it can be reset to 6 mm or smaller, and then adjusted to 7 or 8 mm. This process can be repeated as needed to set the appropriate diameter.

[0040] Because the central segment 14 will be covered with ePTFE or other suitable material, this covering will prevent bile or other fluids from the liver from entering the bloodstream. This also means that surrounding tissues will not slowly enter the stent graft 10, so even weeks or months after implantation, changes in the diameter of the stent graft 10 as it expands or contracts will not damage the surrounding liver tissue.

[0041] Figure 2A more detailed view of a second embodiment of the invention is shown. The stent graft 110 includes a first self-expanding segment 112 and a second self-expanding segment 116. Together with the central segment 114, they form the tubular component 111 of the TIPS stent graft 110. As can be seen from the figures, a lumen 113 extends from one end through the stent graft 110 to the corresponding other end.

[0042] A coil 120 made of Nitinol is arranged around the central section 114. This coil is connected via a wire 121. Figure 3 The electrodes 122 and 124 are shown. Through these electrodes 122 and 124, current can be conducted through the coil 120, which will heat the coil 120. If this heating raises the coil 120 above its transition temperature, the coil 120 will take on a configuration with a smaller circumference, thereby shrinking the central section 114.

[0043] Figure 3 Showing more details Figure 2 The scaffold graft 110 shown is in a configuration with a catheter 130 inserted. The catheter 130 has two expanded sections 140 holding electrodes 142, 144. These electrodes are adjacent to and abut against electrodes 122, 124 of the scaffold graft. A narrower section 139 is disposed between the expanded sections 140, 141 and located inside the central section 114. When a voltage is applied to the electrodes 142, 144 of the catheter 130 via a conductor (not shown) disposed inside the catheter 130, current flows through the conductor forming a coil 120. The coil 120 then heats up and, if heated above its transition temperature, exhibits a more contracted configuration, as previously described. Figure 2 The subject of discussion.

[0044] Figure 4 A third embodiment of the invention is shown. A central section 214 with a smaller diameter is arranged between the first self-expanding section 212 and the second self-expanding section 216. This section is surrounded by a tubular collar 220. This collar is connected to electrodes (not shown) disposed inside the scaffold graft 210. When a voltage is applied to these electrodes, current flows through the collar 220, which causes the collar 220 to heat up and contract, thus exhibiting a contracted configuration. Accordingly, this reduces the cross-sectional area of ​​the scaffold graft 210. Further details of the scaffold graft 210 are described below. Figure 3 The same as shown.

Claims

1. TIPS scaffold grafts, including: A tubular component having a lumen extending therethrough. The tubular component includes a balloon-inflatable central section and a first self-inflating section and a second self-inflating section, the first and second self-inflating sections sandwiching the central section, and the lumen extending through the first self-inflating section, the central section, and the second self-inflating section. The TIPS stent graft includes means for restricting the central segment, thereby reducing the cross-sectional area of ​​the TIPS stent graft available for blood flow, allowing the TIPS stent graft to selectively restrict the central segment. The central segment comprises a shape memory alloy having a transformation temperature above body temperature, and is configured to exhibit a more contracted configuration when heated above its transformation temperature than the first and second self-expanding segments in their expanded state. The TIPS scaffold graft also includes a shrinkage device (120) for selectively shrinking the central segment. The shrinking device is a collar that wraps around the central section (114), the collar being arranged to selectively reduce its inner diameter to shrink the central section.

2. The TIPS scaffold graft according to claim 1, wherein, The collar is arranged to selectively reduce its inner diameter when heating is applied.

3. The TIPS scaffold graft according to claim 1 or 2, wherein, The collar is made of metal.

4. The TIPS scaffold graft according to claim 1 or 2, wherein the collar is arranged to heat up when electrical energy is applied to thereby reduce its inner diameter, and the TIPS scaffold graft further includes electrodes for supplying power to the collar.

5. The TIPS scaffold graft according to claim 4, wherein the electrode is formed on the inner side of the TIPS scaffold graft.

6. The TIPS scaffold graft according to claim 5, wherein the electrode comprises a first electrode and a second electrode, wherein the first electrode (122) is disposed on the first self-expanding section (112) and the second electrode (124) is disposed on the second self-expanding section (114).

7. The TIPS scaffold graft according to claim 1 or 2, wherein the annulus is formed into a cylindrical body (220).

8. The TIPS scaffold graft according to claim 1 or 2, wherein the annular sleeve becomes a coil.

9. The TIPS scaffold graft according to claim 1 or 2, wherein, The collar is made of shape memory alloy.

10. The TIPS scaffold graft of claim 9, wherein the shape memory alloy has a higher transition temperature than the first self-expanding segment and the second self-expanding segment.

11. A kit comprising a TIPS scaffold graft and catheter according to any one of claims 4 to 6, the catheter comprising electrodes arranged to supply power to electrodes of the TIPS scaffold graft.

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