Systems and methods for delivering retrievable stents

Abstract

The present invention is entitled "System and method for delivering a retrievable stent". The present invention discloses a system and method for delivering and deploying an expandable stent to treat intracranial atherosclerotic disease (ICAD) involving large and medium-sized blood vessels. The disclosed system includes: a catheter; a through-barrel, the through-barrel including a distal end disposed within the catheter; an expandable stent, the expandable stent including a proximal end and a distal end, wherein the through-barrel is connected to the expandable stent and the through-barrel is disposed within the expandable stent; and a plurality of struts, wherein the first end of each strut is connected to the through-barrel and the second end of each strut is connected to the expandable stent. The longitudinal movement of the through-barrel relative to the expandable stent causes the plurality of struts to extend radially outward and expand the expandable stent similar to an umbrella. The plurality of struts provide radial force to the expandable stent in an expanded configuration relative to the patient's blood vessel wall.

Description

[0001] Related Cases

[0002] This patent application is a continuation-in-part of U.S. patent application No. 16 / 189,596, filed on November 13, 2018 and entitled “SYSTEMS AND METHODS FORDELIVERY RETRIEVABLE STENTS,” which is hereby incorporated by reference in its entirety. Background Art

[0003] The present disclosure relates generally to the field of endovascular treatment of blood vessels. More specifically, some embodiments relate to endovascular treatment of hemodynamically significant intracranial atherosclerotic disease (ICAD). Summary of the invention

[0004] Intracranial atherosclerotic disease (ICAD) involving large and medium-sized vessels is the leading cause of ischemic stroke worldwide, with an estimated incidence of up to 50%. It is prevalent primarily in Asia, South America, and the Middle East and is less common in Europe and North America. It accounts for 8% to 10% of all ischemic strokes in North America and 30% to 50% in Asia. The three main mechanisms leading to ischemic stroke are hypoperfusion, branch artery atheromatous disease, and artery-to-artery embolism.

[0005] Current endovascular treatment of ICAD in the acute and subacute settings is very limited due to suboptimal current technology, limited ability to perform balloon angioplasty due to the high chance of reocclusion, and the need for permanent stenting.

[0006] The present disclosure proposes a novel method for endovascular treatment of hemodynamically significant ICAD that aims to achieve adequate revascularization without the complications associated with currently available techniques involving placement of occluding balloons for angioplasty and implantation of permanent stents. The method and design allow for temporary and long-term deployment of retrievable stents with adjustable radial force. Additionally, the present application allows for continuous flow and parent vessel conformability as an attractive alternative to balloon angioplasty and stenting. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The written disclosure herein describes non-limiting and non-exhaustive exemplary embodiments. Reference is made to certain of such exemplary embodiments illustrated in the accompanying drawings.

[0008] Figure 1 An expandable stent is shown in a collapsed configuration according to one embodiment.

[0009] Figure 2 Shown in expanded configuration Figure 1 Expandable stent.

[0010] Figure 3 Shows Figure 2 Cross-sectional view of an expandable stent.

[0011] Figure 4 A diagram showing the anatomical advancement path of an expandable stent system is shown.

[0012] Figure 5 is a schematic diagram of an expandable stent including a plurality of struts in a collapsed or semi-collapsed configuration according to one embodiment.

[0013] Figure 6 In the expanded configuration Figure 5 Schematic diagram of an expandable stent.

[0014] Figure 7 An expandable stent is shown in an expanded configuration, the expandable stent comprising a proximal section, a central section, and a distal section, each section having a different stent design according to one embodiment.

[0015] Figure 8 An expandable stent is shown in an expanded configuration including a cover according to one embodiment.

[0016] Fig. 9 A method of deploying an expandable stent in the vasculature of a patient is shown according to one embodiment.

[0017] Fig.10 A braided expandable stent is shown in a collapsed configuration according to one embodiment.

[0018] Fig.11 Shown in expanded configuration Fig.10 Braided expandable stent.

[0019] Fig.12 A braided expandable stent is shown in a collapsed configuration according to one embodiment.

[0020] Fig.13 Shown in an expanded and bent configuration Fig.12 Braided expandable stent. DETAILED DESCRIPTION

[0021] The natural history of ICAD derived from randomized data involving medical treatment shows that the recurrent stroke rate is proportional to the degree of stenosis with extremely high risk in the severe (>70%) category. These data prompted the first randomized clinical trial, SAMMPRIS, to compare angioplasty and stenting with optimal medical treatment (dual antiplatelet therapy using ASA and Plavix, statin, with an LDL target of the statin ≤70 mg / dl and an SBP target <130 / 80). The results of this trial showed that the risk of stroke was worse (23%) after percutaneous angioplasty and stenting (PTAS) using the Wingspan system compared with optimal medical treatment (15%). Another trial called VISSIT involving balloon-mounted stents showed very similar results to SAMMPRIS. However, although medical treatment is superior to endovascular treatment, both trials clearly show that a large number of patients are still at high risk of stroke when treated with invasive medical management. This failure of medical treatment for ICAD can be explained by the inappropriate selection of appropriate treatment based on careful consideration of each of the different pathophysiological mechanisms listed above. Patients with severe stenosis associated with distal hemodynamic impairment and poor collaterals have the highest risk of recurrent ischemic stroke and are logically less likely to benefit from antiplatelet and lipid-lowering therapy. Post hoc analysis of the medical arm of the SAMMPRIS trial showed that the most common infarct pattern was border zone (52.4%), followed by regional (23.8%) and perforating (23%). Patients with border zone infarcts are more likely to have poor collaterals and have a higher risk of recurrent stroke. Thus, current data provide compelling evidence that despite the best medical treatment, patients with severe intracranial stenosis associated with distal hypoperfusion are still at the highest risk of recurrent stroke and these patients may benefit from endovascular revascularization. This insight is supported by evidence from the Chinese stenting registry, which confirmed the low perioperative risk in patients with severe hypoperfusion, short-segment lesions, and treatment within 3 weeks of a qualifying event. Similar results were obtained in the recently completed WEAVE single-arm trial, which enrolled only patients who met the current FDA recommendations for intracranial PTAS using the Wingspan system (demonstrating medical treatment and treatment failure after at least 7 days of a qualifying event). Both studies involved strict patient selection using focal Mori type A lesions and extended the treatment time after stroke and showed excellent results compared with SAMMPRIS and VISSIT.However, these limitations significantly limit the applicability of PTAS, as they are only applicable to a subset of ICAD patients with severe stenosis. Therefore, endovascular revascularization for ICAD is currently limited to patients who have failed medical therapy and only 7 days after TIA or stroke. In addition, the only device approved on the U.S. market is the Wingspan / Gateway balloon system, which is an outdated technology that requires a complex exchange process. In view of its design (self-expansion, high radial force with a strong vessel straightening effect), the device can also only be used for focal short segment stenosis (Mori A type), and does not work in more extensive plaques (Mori b type and Mori c type) and tortuous intracranial anatomical structures.

[0022] In addition to less stringent patient selection, the reasons for PTAS failure have been attributed to technical factors (vessel rupture and guidewire perforation) and medical factors (plaque snow-plowing effect caused by perforator occlusion and delayed intraparenchymal bleeding).

[0023] Perforator occlusion after stenting: Unlike coronary and peripheral vessels, intracranial vessels affected by ICAD have multiple tiny perforators (80-400 microns) that arise from the lateral wall and supply important subcortical structures. Balloon inflation followed by permanent stenting results in “snow-plowing” of the vessel wall by plaque, which is associated with the risk of occlusion of these perforators and subsequent subcortical stroke. (Table 1 highlights the differences between intracranial and coronary vessels).

[0024] Hemorrhagic transformation of ischemic infarction: The infarcted brain parenchyma is particularly sensitive to hemorrhagic transformation, especially in the setting of reperfusion and dual antiplatelet therapy (DAPT) required for any permanent stent implantation.

[0025] Vessel rupture. As mentioned above, tortuous intracranial vessels are particularly susceptible to dissection due to the lack of external elastic plates and poor tissue support. Dissection can be caused by invasive and repeated balloon angioplasty in the setting of reocclusion and severe elastic recoil. Guidewire perforation is another important factor, especially in the context of the exchange procedure required by the Wingspan system. The cervical and intracranial tortuosity of ICAD patients leads to inevitable guidewire instability during the exchange procedure due to distal guidewire tip displacement, with the attendant risk of vessel rupture.

[0026] Delayed thrombosis and restenosis are common complications of any permanent stent implantation, with an estimated symptomatic rate of up to 14% in ICAD.

[0027] Table 1. Important differences between intracranial and coronary vessels :

[0028]

[0029] Angioplasty alone has historically been considered the initial endovascular treatment for ICAD and has recently re-emerged as an alternative to permanent stenting. Multiple case series and studies have suggested that angioplasty alone without permanent stenting may be a viable option for severe ICS with hemodynamic compromise. However, unpredictable degrees of elastic recoil are a common pitfall, leading to immediate reocclusion, as well as a high risk of subacute restenosis due to intimal hyperplasia. One of the methods cited to prevent dissection and reocclusion is long-term dilatation. However, in the intracranial vasculature, this technique carries a high risk of cerebral ischemia due to prolonged vessel occlusion.

[0030] Another limitation of the current technology (Gateway balloon) is that delivery and deployment requires exchange via microwires that are typically positioned in the M2 / M3 segments. As mentioned above, this exchange process is independent of the risk of intracranial vascular perforation due to the high likelihood of guidewire instability in the context of tortuosity in the proximal vasculature and atherosclerotic disease often seen in this patient population.

[0031] Furthermore, despite the demonstrated benefits of thrombectomy for the treatment of acute ischemic stroke (AIS) due to large vessel occlusion (LVO), currently available devices effectively harvest clots of proximal embolic origin rather than in-situ atherothrombi. This limitation is particularly relevant to the Asian population, in which ICAD is the leading cause of ischemic stroke.

[0032] Another important limitation of acute revascularization in the setting of acute large vessel occlusion (LVO) due to underlying ICAD is the need for rescue stenting after failed thrombectomy, which is associated with a 17% to 20% risk of symptomatic intracranial hemorrhage.

[0033] Therefore, current endovascular treatments for ICAD in the acute and subacute setting are very limited due to suboptimal current technology, limited ability to perform balloon angioplasty due to the high chance of reocclusion, and the need for permanent stent implantation.

[0034] The components of the embodiments as generally described and shown in the figures herein may be arranged and designed into a variety of different configurations. Therefore, the following more detailed description of the various embodiments represented in the figures is not intended to limit the scope of the present disclosure, but merely represents various embodiments. Although various aspects of the embodiments are presented in the drawings, unless explicitly indicated, the drawings are not necessarily drawn to scale.

[0035] The phrase "coupled to" is broad enough to refer to any suitable connection or other form of interaction between two or more entities, including mechanical, fluid, and thermal interactions. Two components can be coupled to each other even if they are not in direct contact with each other. The phrases "attached to" or "directly attached to" refer to an interaction between two or more entities that are in direct contact with each other and / or separated from each other only by any suitable kind of fastener (e.g., mounting hardware or adhesive). The phrase "fluid communication" is used in its ordinary sense and is broad enough to refer to an arrangement in which a fluid (e.g., a gas or liquid) can flow from one element to another element when the elements are in fluid communication with each other.

[0036] The terms "proximal" and "distal" are opposite directional terms. For example, the distal end of a device or component is the end of the component farthest from the practitioner during normal use. The proximal end refers to the opposite end, or the end closest to the practitioner during normal use.

[0037] The present disclosure relates to expandable stents. Expandable stents can fall into a number of different categories, such as laser cut stents cut from a hypotube and braided stents that include woven individual guidewires. Figure 1 A retrievable expandable stent delivery system 100 for endovascular treatment of hemodynamically significant intracranial atherosclerotic disease (ICAD) is shown. The retrievable expandable stent delivery system 100 includes a catheter 200, a through-tube 300, and an expandable stent 400. The through-tube 300 and the expandable stent 400 may be disposed within the catheter 200. The catheter 200 may be a microcatheter and have an inner diameter ranging from 0.017 inches to 0.021 inches. The through-tube 300 and the expandable stent 400 may be configured to be slidably advanced within the catheter 200. In some embodiments, the catheter 200 and the through-tube 300 may be coupled to a handle (not shown) that may enable a user to manipulate the catheter 200, the through-tube 300, and the expandable stent 400 coupled to the through-tube 300.

[0038] In some embodiments, the through-tube 300 may include an inner lumen. The inner lumen of the through-tube 300 may enable the retrievable expandable stent delivery system 100 to be advanced over a guidewire (not shown) that has been previously advanced to a target location. The through-tube 300 includes a distal end 302. The distal end 302 of the through-tube 300 may have a rounded tip that may help prevent vessel perforation during surgery.

[0039] In some embodiments, a retrievable expandable stent 400 may be coupled to the barrel 300. For example, a distal end 402 of the expandable stent 400 may be coupled to the distal end 302 of the barrel 300. A proximal end 404 of the expandable stent 400 may be coupled to a collar 406 that is configured to include the barrel 300. The collar 406 may be configured to slide longitudinally on the barrel 300. In some embodiments, the collar 406 may be locked in a specific positioning position relative to the barrel 300, thereby enabling the distal end 402 of the expandable stent 400 to move relative to the proximal end 404. The relative movement between the distal end 402 and the proximal end of the expandable stent 400 may be controlled by the aforementioned handle, which may be manipulated by a user.

[0040] In some embodiments, relative movement between distal end 402 and proximal end 404 of expandable stent 400 is configured to expand expandable stent 400 . Figure 1 The expandable stent 400 is shown in a collapsed configuration, and Figure 2 Expandable stent 400 is shown in an expanded configuration. Similarly, relative movement between distal end 402 and proximal end 404 can also cause expandable stent 400 to collapse after the procedure is completed.

[0041] In some embodiments, the expandable stent 400 may be made of a memory material such as nitinol, and when the expandable stent 400 is sheathed by the catheter 200, the expandable stent 400 may be in a collapsed configuration. When the expandable stent 400 is unsheathed from the catheter 200, the expandable stent 400 may expand, so that the expandable stent 400 expands into a predetermined shape. Unsheathing may occur by advancing the expandable stent 400 from the catheter 200 or by retracting the catheter 200 from the expandable stent 400. The expandable stent 400 may be collapsed by re-sheathing the expandable stent 400 after the operation is completed. Re-sheathing may occur by retracting the expandable stent 400 into the catheter 200 or by advancing the catheter 200 on the expandable stent 400.

[0042] Figure 2 The retractable expandable stent delivery system 100 is shown with the expandable stent 400 in an expanded configuration. The expandable stent 400 can have a number of different design features. Figure 2 The illustrated embodiment shows a central region of an expandable stent 400 having a tubular linear shape and a plurality of closed cells.

[0043] In some embodiments, the stent may have a tapered configuration. For example, the stent may taper from the proximal end of the stent to the distal end of the stent. In another embodiment, the stent may taper from the distal end of the stent to the proximal end. In another embodiment, the stent may taper from the center of the stent in opposite directions. For example, the stent may taper from the center of the stent to the distal end of the stent, and may taper from the center of the stent to the proximal end of the stent in opposite directions.

[0044] In some embodiments, the stent may have multiple closed cells instead of multiple open cells. In other embodiments, the pores of the stent may be a mixed pore design including multiple closed cells and multiple open cells. The pore design can be manufactured in a variety of ways, such as laser cutting, etc. In some embodiments, the expandable stent 400 may have a braided design. A braided (or alternative) design with a porosity of about 30% allows adequate plaque coverage without occlusion of perforating vessels. The braided technology also allows the parent vessel to have greater flexibility and conformability, which is a typical feature of the intracranial vasculature.

[0045] In some embodiments, the outer surface of expandable stent 400 may have a porosity in a range of 10% to 35%. In some embodiments, expandable stent 400 may have a porosity in a range of 15% to 30%.

[0046] exist Figure 2 In the illustrated embodiment, the expandable stent 400 may also include a plurality of struts 410, which are configured to help expand the expandable stent 400 from a collapsed configuration to an expanded configuration. The first end 412 of each strut 410 may be coupled to the through-tube 300, and the second end 414 of each strut 410 may be coupled to the expandable stent 400. The longitudinal movement of the through-tube 300 relative to the expandable stent 400 may cause the plurality of struts 410 to extend radially outward and expand the recyclable expandable stent 400 from a collapsed configuration to an expanded configuration. The struts 410 are configured to help maintain the shape of the expandable stent 400 in an expanded configuration.

[0047] A plurality of struts 410 may be longitudinally disposed along the barrel 300 between the distal end 402 and the proximal end 404 of the expandable stent 400. The struts 410 may be equally spaced along the barrel 300, or the struts 410 may not be equally spaced along the barrel 300. In some embodiments, the struts 410 may be disposed in subgroups along the barrel 300. For example, Figure 2 Several subsets are shown, namely a first subset 416 of struts disposed in the proximal portion, a second subset 418 of struts disposed in the central portion, and a third subset 420 of struts disposed in the distal portion of expandable stent 400 .

[0048] In some embodiments, the struts 410 may be radially spaced around the through-tube 300. Figure 3 It is shown in Figure 3 For along Figure 2 A cross-sectional view of the retrievable expandable stent delivery system 100 is shown taken along cross-sectional line 3-3. Figure 3 A plurality of struts 410 are shown spaced radially about the through-barrel 300. In the illustrated embodiment, the struts 410 may be equally spaced about the through-barrel 300. In other embodiments, the struts 410 may not be equally spaced about the through-barrel 300. Figure 3 Six struts 410 are shown; however, the disclosure is not so limited and there may be more or less than six struts. There may be as few as three struts 410 disposed around the through barrel 300 and as many as 10 struts 410 disposed around the through barrel 300 in a single subset of struts 410.

[0049] In some embodiments, struts 410 disposed along the shaft 300 can be radially aligned with other struts 410 disposed along the shaft 300. For example, the first subset 416, the second subset 418, and the third subset 420 can each include a plurality of struts 410 disposed about the shaft 300 and radially aligned with each other. The radial alignment of the struts can create a plurality of channels 422 extending from the distal end 402 to the proximal end 404 of the expandable stent 400. The channels 422 can enable blood flow or blood perfusion through the expandable stent 400 in the expanded configuration.

[0050] In some embodiments, the longitudinal length of expandable stent 400 in the expanded configuration can range between 5 mm and 30 mm.

[0051] Figure 4 Shown is a diagram of the anatomical route of a retrievable expandable stent delivery system 100. A catheter 200 may be inserted into a patient's femoral artery (using, for example, the Seldinger technique) and advanced upward through the patient's aorta 10, from where the catheter 200 may be advanced upward through the carotid artery 20 to an intracranial target location. Figure 4An intracranial target location is shown; however, other vascular system target locations within the vascular system of the patient are targeted. The target location may be a partially occluded or completely occluded blood vessel that can be treated with a recyclable expandable stent delivery system 100. Once the catheter 200 has reached the target location, the through tube 300 and the expandable stent 400 may be pushed out of the catheter 200. The expandable stent 400 may be expanded and the stent may contact a plaque disposed on the vessel wall, and the expandable stent 400 may squeeze or rupture the plaque via the adjustable radial force of the expandable stent 400. The expandable stent 400 may be deployed (expanded) at the target location for a longer period of time (up to 30 minutes), thereby allowing the vessel to be non-occluded and distal antegrade flow. The expandable stent 400 may be deployed in a blood vessel having a diameter between 1.5 mm and 7 mm.

[0052] In certain embodiments, the expandable stent 400 in the expanded configuration has the ability to keep the vessel open for 15-30 minutes while the radial force of the expandable stent 400 keeps the plaque from recoiling, thereby minimizing the risk of elastic recoil and reocclusion after the expandable stent is retrieved. The porosity of the expandable stent 400 minimizes the risk of perforator occlusion and snow removal compared to a balloon that uniformly covers the plaque.

[0053] In some embodiments, expandable stent 400 can be removed from barrel 300 and left in the target area for long-term treatment. Expandable stent 400 can be removed at a removal area, which can correspond to a proximal end 404 of expandable stent 400, by mechanical removal or electrolysis, thermomechanical or other removal mechanisms.

[0054] The expandable stent 400 may be radiopaque or may include a plurality of radiopaque markers that may enable a user or medical professional to visualize the retrievable expandable stent delivery system 100 using medical imaging.

[0055] Figure 5 and Figure 6 Schematic diagram of the deployment and expansion of expandable stent 400. Expandable stent 400 opens radially like an umbrella. Figure 5 The expandable stent 400 is shown in a collapsed or semi-collapsed configuration. In the collapsed or semi-collapsed configuration, the struts 410 are angled at an angle θ1 relative to the barrel 300. In some embodiments, the angle θ1 can range between 0 and 15 degrees in the collapsed configuration. In some embodiments, the angle θ1 can range between 0 and 75 degrees in the semi-collapsed configuration. Figure 5 Struts 410 are shown oriented in the distal direction. When multiple struts are oriented in the distal direction, re-sheathing of the stent can be facilitated. In some embodiments, struts 410 can be oriented in the proximal direction.

[0056] like Figure 6 As shown, the user can expand the expandable stent 400 into the expanded configuration by extending the plurality of struts 410 radially outward, which expands the expandable stent 400. In the expanded configuration, the struts 410 can be angled relative to the barrel 300 at an angle θ2. In some embodiments, the angle θ2 range can be between 45 degrees and 90 degrees. In some embodiments, the angle θ2 range can be between 75 degrees and 90 degrees. The angle θ2 determines the amount of radial force applied to the expandable stent 400 in the expanded configuration. The closer the angle θ2 is to 90 degrees, the greater the radial force applied to the expandable stent 400 by the struts 410. This enables the user to apply an adjustable radial force to the outer surface of the expandable stent 400, and the adjustable radial force varies in relation to the angle of the struts relative to the barrel 300. For example, the smaller the angle, the smaller the radial force, and the larger the angle, the greater the radial force, up to 90 degrees. Thus, a user can control the amount of radial force applied to the patient's vessel wall by controlling the movement of the barrel 300 and the radially outward movement of the plurality of struts 410. The struts 410 can apply a radial force between 0.00590 Newtons / mm and 0.0090 Newtons / mm.

[0057] As previously described, the distal end 302 of the barrel 300 may be coupled to the distal end 404 of the expandable stent 400. The barrel 300 may include a locking mechanism 310 configured to prevent the proximal end 404 of the expandable stent 400 from moving relative to the barrel 300. The locking mechanism may be implemented via a handle that locks the barrel 300 relative to the catheter 300.

[0058] Expandable stent 400 may be expanded from a collapsed configuration to an expanded configuration by moving distal end 402 of expandable stent 400 toward proximal end 404 of expandable stent 400. This may be accomplished by engaging locking mechanism 310 and preventing movement of distal end 402 of expandable stent 400. Similarly, expandable stent 400 may be collapsed from an expanded configuration to a collapsed configuration by moving distal end 402 of expandable stent 400 away from proximal end 404 of expandable stent 400.

[0059] The expandable stent 400 can be expanded by applying a proximally directed force (lifting) to the through-barrel 300. The distal end 302 of the through-barrel 300 is coupled to the distal end 402 of the expandable stent 400, and the distal end 402 of the expandable stent 400 is pulled toward the proximal end 404 of the expandable stent 400. The proximal end 404 of the expandable stent 400 is locked in place via the locking mechanism 310, and the movement of the proximal end 404 is prevented when a proximally directed force is applied to the through-barrel 300. The reverse movement will collapse the expandable stent 400 from the expanded configuration to the collapsed configuration.

[0060] like Figure 5 As shown, the expandable stent 400 can also be expanded by applying a distally directed force (push) to the expandable stent 400. In this configuration, the distal end 302 of the through-tube 300 and the distal end 402 of the expandable stent 400 are coupled together. The expandable stent 400 can be coupled to an outer through-tube including the through-tube 300, and the user can apply a distally directed force to the outer through-tube to move the proximal end 404 of the expandable stent 400 toward the distal end 402 of the expandable stent 400.

[0061] Figure 7 An embodiment of a retrievable expandable stent delivery system 100' is shown that is similar in some respects to the retrievable expandable stent delivery system 100 described above. Therefore, similar features are designated by similar reference numerals with a prime added. For example, Figure 7 The embodiment shown in FIG. 1 includes a through-tube 300 ′, which may be similar in some respects to the through-tube 300 ′ of FIG. Figures 1 to 3 and Figures 5 and 6 Therefore, the above-mentioned disclosure contents related to the characteristic parts with similar marks may not be repeated below. Figures 1 to 3 and Figures 5 and 6 Specific features of the illustrated retrievable expandable stent delivery system 100 and related components may not be shown or identified by reference numerals in the drawings, or may not be specifically discussed in the subsequent written description. However, such features may be clearly the same or substantially the same as features shown in other embodiments and / or described with respect to such embodiments. Therefore, the relevant description of such features also applies to Figure 7 Features of the depicted retrievable expandable stent delivery system 100' and associated components. Figures 1 to 3 and Figures 5 and 6 Any suitable combination and variations of the features described for the illustrated retrievable expandable stent delivery system 100 and associated components may be used in Figure 7The retrievable expandable stent delivery system 100' and related components and vice versa. This disclosure is equally applicable to other embodiments shown in subsequent figures and described below, where the primes may be further incremented.

[0062] Figure 7 A retrievable expandable stent delivery system 100' is shown, which includes a catheter 200', a through-tube 300' and an expandable stent 400'. The expandable stent 400' may include a proximal portion 430', a central portion 440' and a distal portion 450'. Each portion may have a different design configuration. For example, the proximal portion 430' and the distal portion 450' include a plurality of closed cells. The central portion 440' may include a spiral segment, which includes a plurality of spiral guidewires that rotate around the through-tube 300'. The spiral segment may provide additional flexibility to the expandable stent 400' to help enable the expandable stent 400' to conform to or adapt to the curvature of the vessel without too much vessel straightening effect and minimal plaque or vessel damage.

[0063] Figure 8 A retrievable expandable stent delivery system 100" is shown, wherein the retrievable expandable stent delivery system 100" includes a catheter 200", a through cylinder 300", and an expandable stent 400". The expandable stent 400" may include a porous covering 460". The covering 460" may be a fine woven mesh, electrospun PTFE, laser cut polyurethane, a porous nitinol film, or other suitable material.

[0064] In some embodiments, the covering 460" can have a hydrophilic surface that helps minimize thrombosis. In some embodiments, the expandable stent 400" can have a hydrophilic surface, such as a hydrophilic coating that helps minimize thrombosis.

[0065] Fig. 9 A method of deploying an expandable stent 400 in a patient's vasculature is shown. Step S1000 describes inserting a catheter 200 into the patient's vasculature. As previously described, the catheter 200 can be inserted into the patient's femoral artery (using, for example, the Seldinger technique). However, the catheter 200 can be inserted into a variety of different locations in the patient's vasculature. Step S1010 describes advancing the expandable catheter 200 to the target location. Figure 4 Advancement upward through the patient's aorta 10 is shown; from there the catheter 200 may be advanced upward through the carotid artery 20 to an intracranial target location. Other vasculature target locations are within the scope of the present disclosure and are located anywhere within the patient's vasculature.

[0066] Step S1020 describes unsheathing expandable stent 400 from catheter 200. This may be accomplished by pushing expandable stent 400 out of catheter 200 or by retracting catheter 200 from expandable stent 400.

[0067] Step S1030 describes expanding the expandable stent 400. As previously described, the expandable stent 400 may expand because it is made of a memory material such as Nitinol, or the expandable stent 400 may expand via relative movement of the distal end 402 of the expandable stent 400 toward the proximal end 404 of the expandable stent 400. This movement may occur via an umbrella-like motion, by pulling the through-tube 300 and extending the plurality of struts 410 radially outward to expand the expandable stent 400.

[0068] Step S1040 describes treating a blood vessel at a target location in a patient. The treatment relies on expanding the expandable stent 400 and squeezing or rupturing the plaque at the target location. The struts 410 provide an adjustable radial force to squeeze or rupture the plaque and maintain the shape of the expandable stent 400. The amount of radial force applied by the expandable stent is adjustable and controllable by the user. As previously described, the relative angle of the plurality of struts 410 relative to the barrel 300 determines the amount of force applied by the outer surface of the expandable stent 400. The smaller the angle, the smaller the radial force, and the larger the angle, the greater the radial force, up to 90 degrees. Treatment of the blood vessel can be performed for a predetermined amount of time (up to 30 minutes), or the expandable stent 400 can be removed from the barrel 300 and left in place for a long time, pending possible recovery later.

[0069] Step S1050 describes collapsing expandable stent 400 into its collapsed configuration after treatment has been performed. Once expandable stent 400 is in its collapsed configuration, expandable stent 400 may be resheathed as described in step S1060. Expandable stent 400 may be resheathed by retracting expandable stent 400 within catheter 200 or by advancing catheter 200 over expandable stent 400.

[0070] Step 1070 describes removing catheter 200 from the patient's vasculature after treatment of the vessel has been completed.

[0071] Fig.10 and Fig.11A retrievable expandable stent delivery system 100"' is shown, and the retrievable expandable stent delivery system 100"' includes a catheter 200"', a through-barrel 300"' and an expandable stent 400"'. The through-barrel 300"' can be connected to the expandable stent 400"'. The through-barrel 300"' and the expandable stent 400"' can be arranged together with the catheter 200"', and can be constructed to be slidably advanced within the catheter 200"'. In some embodiments, the catheter 200"' and the through-barrel 300"' can be connected to a handle (not shown), and the handle can enable a user to manipulate the catheter 200"', the through-barrel 300"' and the expandable stent 400"' connected to the through-barrel 300. In some embodiments, the retrievable expandable stent delivery system 100"' can be arranged within an outer catheter (not shown), and the retrievable expandable stent delivery system 100"' can slide along the length of the outer catheter.

[0072] The expandable stent 400"' may include a plurality of filaments 408"' extending from a distal end 402"' to a proximal end 404"' of the expandable stent 400"'. In each embodiment, the number of filaments may vary. For example, the number of filaments 408"' may range between 5 filaments and 40 filaments. The filaments 408"' may be made of a variety of different materials, such as nitinol, nitinol alloy, stainless steel, stainless steel alloy, polyester multifilament, platinum alloy, or other composite materials, or combinations or blends of the aforementioned materials. The porosity of the expandable stent 400"' can be variable. For example, as the expandable stent 400"' expands, the porosity of the expandable stent 400"' can increase. In addition, the number of filaments 408"' can affect the porosity of the expandable stent 400"'. For example, the more filaments 408"' the expandable stent 400"' has, the lower the porosity of the expandable stent 400"'. In some embodiments, the porosity of the expandable stent 400"' can be in the range of 5% to 45%.

[0073] The filaments 408'" can be woven in a weaving pattern so that the expandable stent 400'" forms a mesh. For example, the filaments 408'" can be woven in a half-loaded weaving pattern, a full-loaded weaving pattern, a diamond weaving pattern, etc. The half-loaded pattern includes a first group of filaments 407'" (e.g., weft filaments) and a second group of filaments 409'" (warp filaments), wherein the first group of filaments 407'" rotates in an opposite direction to the second group of filaments 409'"'. The first group of filaments 407'" is woven into an overlapping pattern with the second group of filaments 409'"'. In other words, the filaments of the first group of filaments 407'" are alternately above one filament of the second group of filaments 409'"', below another filament of the second group of filaments 409'"', and above another filament of the second group of filaments 409'"', etc., until the filaments reach the opposite end of the expandable stent 400'" (e.g., the distal end 402'" or the proximal end 404'").

[0074] In some embodiments, the braiding pattern is a fully loaded braiding pattern. Thus, the first group of filaments 407'" is braided with the second group of filaments 409'" in a two-on-two-off pattern. In other words, the filaments of the first group of filaments 407'" are alternately above two filaments of the second group of filaments 409'"', below another two filaments of the second group of filaments 409'"', above another two filaments of the second group of filaments 409'"', and so on, until the filaments reach the opposite end of the expandable stent 400'" (e.g., the distal end 402'" or the proximal end 404'").

[0075] In some embodiments, the braiding pattern is a diamond braiding pattern. Therefore, the two side-by-side filaments of the first group of filaments 407' are braided together with the second group of filaments 409' in a two-on-two-off pattern. In other words, the two side-by-side filaments of the first group of filaments 407' are alternately above the two filaments of the second group of filaments 409', below the other two filaments of the second group of filaments 409', above the other two filaments of the second group of filaments 409', and so on, until the two filaments reach the opposite ends of the expandable stent 400' (e.g., the distal end 402' or the proximal end 404').

[0076] In some embodiments, a retrievable expandable stent 400"' may be coupled to a through barrel 300"'. For example, a distal end 402"' of the expandable stent 400"' may be coupled to a distal end 302"' of the through barrel 300"'. A proximal end 404"' of the expandable stent 400"' may be coupled to a distal end of a catheter 200"'. In some embodiments, a proximal end 404"' of the expandable stent 400"' may be attached to a marker band. In some embodiments, relative movement between the distal end 402"' and the proximal end 404"' of the expandable stent 400"' is configured to expand the expandable stent 400"'. Expansion of the expandable stent 400"' may be controlled by a handle that may be manipulated by a user. The through-barrel 300"' is controlled by a handle via a lever, knob or button. The user's manipulation of the lever, knob or button on the handle shortens the through-barrel 300"' (or applies a proximally oriented force to the through-barrel 300"'), which expands the expandable stent 400"'. The expansion of the expandable stent 400"' increases the outward radial force of the expandable stent 400"' on the vessel wall, which can lead to plaque fracturing in narrowed blood vessels plagued by atherosclerosis.

[0077] Fig.10 The expandable stent 400'' is shown in a collapsed configuration with a first diameter D1 and a first length L1, and Fig.11 An expandable stent 400'" is shown in an expanded configuration with a second diameter D2 and a second length L2. The second diameter D2 is greater than the first diameter D1, and the second length L2 is less than the first length L1. Therefore, when a user controls the handle to manipulate the position of the barrel 300'" and move the distal end 402'" of the expandable stent 400'" toward the proximal end 404'" the expandable stent 400'" expands. Fig.10 The through-tube 300' is shown in a first position and Fig.11 The shaft 300'" is shown in a second position, where a change in position of the shaft 300'" changes the diameter of the expandable stent 400'".

[0078] The filaments 408'" are configured to slide against each other and this enables the expandable stent 400'" to have additional flexibility in both the expanded and collapsed configurations. The additional flexibility enables the expandable stent 400'" to conform to the patient's blood vessels, particularly the intracranial vasculature.

[0079] After the procedure is completed, the relative movement between the distal end 402'" and the proximal end 404'" may also cause the expandable stent 400'" to collapse. After the expanded stent 400'" has achieved the desired outward expansion, the procedure may last up to 60 minutes. In some embodiments, the expandable stent 400'" is removed after the procedure is completed. In other embodiments, the expandable stent 400'" may be removed from the barrel 300'" and left in a desired position within the patient's vascular system.

[0080] In some embodiments, the expandable stent 400'" can be drug eluting. The expandable stent 400'" can include a drug covering or coating selected from the group consisting of Everolimus, Paclitaxel, Siromlimus, Corolimus, and any other related compounds, salts, portions that can potentially reduce the risk of thrombosis, lumen loss, and related challenges.

[0081] In some embodiments, the expandable stent 400'" may include a radiopaque marker, such as platinum, gold, silver, or tantalum. In some embodiments, the expandable stent 400'" may be made of a bioresorbable material, such as a magnesium-based material, a polylactic acid (PLA)-based polymer, or the like.

[0082] In some embodiments, the retrievable expandable stent delivery system 100'" further includes a plurality of struts (similar to the struts described above) that are configured to help expand the expandable stent 400'" from a collapsed configuration to an expanded configuration. The first end of each strut may be connected to the through-barrel 300'", and the second end of each strut may be connected to the expandable stent 400'"'. Longitudinal movement of the through-barrel 300 relative to the expandable stent 400'" may cause the plurality of struts to extend radially outward and expand the retrievable expandable stent 400'" from a collapsed configuration to an expanded configuration. The struts are configured to help maintain the shape of the expandable stent 400'" in the expanded configuration and to provide an outward radial force to the expandable stent 400'"'.

[0083] Fig.12 and Fig.13 A retrievable expandable stent delivery system 100"" is shown, wherein the retrievable expandable stent delivery system 100"" includes a catheter 200"" a through tube 300"" and an expandable stent 400"". The expandable stent 400"" is similar to Fig.10 and Fig.11 The expandable stent 400''' is provided, and therefore, repetitive features are not described below. The expandable stent 400''' includes a plurality of filaments in a braided pattern, such as previously disclosed braided patterns. Fig.12The expandable stent 400"" is shown in a collapsed configuration with a first diameter D1' and a first length L1', and Fig.13 Expandable stent 400" is shown in an expanded configuration with a second diameter D2' and a second length L2'. The second diameter D2 is greater than the first diameter D1 and the second length L2 is less than the first length L1.

[0084] Furthermore, the expandable stent 400"" is configured to bend during expansion and conform to the curvature of the parent vessel, such as Fig.13 As shown. The distal end 302"" of the through-tube 300"" is configured to be coupled to the distal end 402"" of the expandable stent 400"". In addition, the through-tube 300"" can be woven into the expandable stent 400"". For example, Fig.12 A through-barrel 300"" is shown being woven in and out of an expandable stent 400"". Thus, when a user pulls on the through-barrel 300", the expandable stent 400"" bends in a direction toward the position where the through-barrel 300"" is woven within the expandable stent 400"". In some embodiments, the through-barrel 300"" may be woven more than once. In some embodiments, the through-barrel 300"" is woven in and out of the braid of the expandable stent 400"" twice. In some embodiments, the through-barrel 300"" is woven in and out of the braid of the expandable stent 400"" three times. In some embodiments, the through-barrel 300"" is woven along the entire length of the expandable stent 400"". The more the through-barrel 300"" is woven into the expandable stent 400", the greater the curvature of the expandable stent 300"".

[0085] In some embodiments, the shape of the expandable stent 400"" may depend on how much of the expandable stent 400"" is deployed outside of an outer catheter (not shown). By not deploying the entire expandable stent 400"" outside of the outer catheter, the expandable amount of the expandable stent 400"" is shortened.

[0086] The braided expandable stent can be used to treat intracranial atherosclerotic stenosis. A method for treating atherosclerotic stenosis may include placing a guide catheter system into the patient's cervical spine and intracranial vascular system, and delivering a microcatheter into a target blood vessel. The braided expandable stent can be deployed outside the microcatheter and across the target lumen to treat stenosis in a collapsed configuration. The user can manipulate the handle of the system, which manipulates the through-tube and expands the braided expandable stent. The stent can remain expanded for up to 60 minutes, or at the discretion of the treating physician. The braided expandable stent applies an outward radial force to the vessel wall to dilate the subject's blood vessel and treat the stenosis. The user can then collapse the braided expandable stent through the handle. Once the device collapses, it can be sheathed in the microcatheter again. The stent may be non-detachable or may not be non-detachable, and may or may not be fully recovered at the end of the operation. The present disclosure is not limited to treating intracranial atherosclerotic stenosis, but can be used in different anatomical locations.

[0087] In some embodiments, the braided expandable stent may be a drug eluting stent. In some embodiments, the braided expandable stent may be a bioabsorbable stent (bioabsorbable stent / magnesium-based material) and / or a stent made of a polylactic acid-based polymer. In some embodiments, the braided expandable stent may be a bare metal self-expanding stent and a chimeric combination or hybrid thereof, thereby reducing the possibility of vascular rupture during surgery.

[0088] In some embodiments, the braided expandable stent may include a coating, marker, system for marking or covering that is radiopaque, wherein the coating, marker, system for marking or covering is partially disposed on only a portion of the surface of the braided expandable stent associated therewith. In some embodiments, heparin and / or vasodilators may be infused during stent deployment to provide durable cerebral vasodilation for patients with multifocal and extensive ICAD.

[0089] In some embodiments, the method of treating ICAD is secondary to another surgery using a non-removable specialized stent. In some embodiments, the braided expandable stent is removable, leaving nothing in the vessel after the stent is retrieved, and also achieving long-term repair of the lumen diameter.

[0090] In some embodiments, the braided expandable stent is atraumatic, thin, radiopaque, and has a robust geometry and is removable. The braided expandable stent may also include at least a drug covering or coating selected from the group consisting of Everolimus; Paclitaxel; Sirolimus; Corolimus, and any related compounds, salts, moieties, and / or stents / stent-means that potentially reduce the risk of thrombosis, lumen loss, and related challenges, are bioabsorbable stents / stents made of magnesium-based materials and / or polylactic acid (PLA) (polymers), the stents / stent-means are implantable as a treatment for ICAD, the stents / stent-means are specifically designed as high radial force devices.

[0091] Any method disclosed herein includes one or more steps or actions for performing the method. The method steps and / or actions are interchangeable with each other. In other words, unless a specific order of steps or actions is required for the correct operation of the embodiment, the order and / or purpose of specific steps and / or actions can be modified. In addition, a subroutine or only a portion of the method described herein can be a separate method within the scope of the present disclosure. In other words, some methods may only include a portion of the steps described in a more detailed method.

[0092] Reference throughout this specification to "an embodiment" or "the embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Therefore, referenced phrases or variations thereof are not necessarily all referring to the same embodiment as described throughout this specification.

[0093] Similarly, those skilled in the art who benefit from the present disclosure should recognize that in order to simplify the present disclosure, in the description of the above-mentioned embodiments, multiple features are sometimes concentrated in a single embodiment, figure or its description. However, this method of disclosure should not be interpreted as reflecting the following intention, that is, any claim requires more features than those features explicitly listed in the claim. On the contrary, as reflected in the following claims, aspects of the present invention lie in a combination of features that are less than all the features of any single aforementioned disclosed embodiment. Therefore, the claims following this specific embodiment are hereby expressly incorporated into this specific embodiment, wherein each claim independently serves as a separate embodiment. The present disclosure includes all arrangements of independent claims and their dependent claims.

[0094] The recitation of the term "first" with respect to a feature or element in the claims does not necessarily imply the presence of a second or additional such feature or element.It will be apparent to those skilled in the art that changes may be made to the details of the above-described embodiments without departing from the basic principles of the disclosure.

Claims

1. A stent delivery system for delivering and deploying an expandable stent, the stent delivery system comprising: catheter; A through-tube, the through-tube comprising a distal end portion, disposed in the catheter; an expandable stent, the expandable stent comprising a proximal end and a distal end, wherein the through-barrel is directly attached to the expandable stent and the through-barrel is disposed within the expandable stent; and a plurality of struts disposed within the expandable stent, wherein a first end of each strut is coupled to the through-tube and a second end of each strut is coupled to the expandable stent, wherein the longitudinal movement of the through-tube relative to the expandable stent pulls the distal end and the proximal end of the expandable stent toward each other, causing the plurality of struts to extend radially outward and causing the expandable stent to expand, wherein the plurality of struts provide an adjustable outward radial force to the outer surface of the expandable stent, The expandable stent comprises a proximal portion, a central portion and a distal portion, wherein the proximal portion and the distal portion include a plurality of closed cells, and The central portion includes a plurality of spiral wires which rotate around the barrel and do not form a closed hole. 2 . The stent delivery system of claim 1 , wherein the distal end of the through barrel is coupled to the distal end of the expandable stent.

3. The stent delivery system of claim 1, wherein a distally directed force applied to the barrel causes the plurality of struts to extend radially outward, thereby expanding the expandable stent.

4. The stent delivery system of claim 1, wherein a proximally directed force applied to the expandable stent causes the plurality of struts to extend radially outward, thereby expanding the expandable stent into an expanded configuration.

5. The stent delivery system of claim 1, wherein the struts are disposed at the distal end of the expandable stent, and the struts are disposed at the proximal end of the expandable stent in an expanded configuration.

6. The stent delivery system of claim 1, wherein the plurality of struts are longitudinally disposed along the expandable stent, and the plurality of struts are radially aligned with each other, and wherein in the expanded configuration, the radial alignment of the plurality of struts creates a plurality of channels.

7. A stent delivery system according to claim 1, wherein the multiple struts include subsets of struts, wherein a first subset of struts is connected to a predetermined position of the through tube and radially spaced apart from each other, and a second subset of struts is connected to a predetermined position of the through tube distal to the first subset of struts and radially spaced apart from each other, and wherein the first subset of struts and the second subset of struts are radially aligned.

8. The stent delivery system of claim 1, wherein the expandable stent in an expanded configuration provides a radial force ranging between 0.00590 Newtons / mm and 0.0090 Newtons / mm.

9. The stent delivery system of claim 1, wherein in the collapsed configuration, the plurality of struts are oriented in a distal direction.

10. The stent delivery system of claim 1, wherein in the expanded configuration, the plurality of struts are oriented in a proximal direction.

11. The stent delivery system of claim 1, wherein the through barrel comprises a locking mechanism, wherein the locking mechanism is configured to lock a position of the proximal end of the expandable stent relative to the distal end of the expandable stent.

12. The stent delivery system of claim 1, wherein the expandable stent comprises a porosity in the range of 10% to 35%.

13. The stent delivery system of claim 1, wherein the expandable stent comprises a porosity in the range of 15% to 30%.

14. The stent delivery system of claim 1, wherein the expandable stent comprises a covering.

15. An expandable stent system, comprising: A through-tube, the through-tube comprising a distal end; an expandable stent, the expandable stent comprising a proximal end and a distal end, wherein the through-barrel is directly attached to the expandable stent and the through-barrel is disposed within the expandable stent; and a plurality of struts disposed within the expandable stent, wherein a first end of each strut is coupled to the through-tube and a second end of each strut is coupled to the expandable stent, wherein the plurality of struts extend radially outward and expand the expandable stent into an expanded configuration, wherein the radially outward movement of the plurality of struts is configured to provide an adjustable outward radial force to the outer surface of the expandable stent, The expandable stent comprises a proximal portion, a central portion and a distal portion, wherein the proximal portion and the distal portion include a plurality of closed cells, and The central portion includes a plurality of spiral wires which rotate around the through cylinder and do not form a closed hole.

16. The expandable stent system of claim 15, wherein longitudinal movement of the barrel relative to the expandable stent causes the plurality of struts to extend radially outward.

17. The expandable stent system of claim 15, wherein the expandable stent in an expanded configuration provides a radial force ranging between 0.00590 Newtons / mm and 0.0090 Newtons / mm.

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