Patent Application
20220378590
The present subject matter relates to endovascular devices and endovascular device systems and related methods that allow for the modulation/regulation of vascular flow. In particular, the present subject matter relates to endovascular stents and endovascular device systems and related methods that allow for the modulation and/or regulation of vascular flow to treat certain disease states.
A major function of the kidneys is to remove waste products and excess fluid from the body. These waste products and excess fluid are removed through the urine. The production of urine involves highly complex steps of excretion and reabsorption. This process is necessary to maintain a stable balance of body chemicals. The critical regulation of the body's salt, potassium and acid content is performed by the kidneys. The kidneys also produce hormones that affect the function of other organs. For example, a hormone produced by the kidneys stimulates red blood cell production. Other hormones produced by the kidneys help regulate blood pressure and control calcium metabolism.
Over 650,000 Americans suffer from kidney failure. Of these, just under 500,000 require dialysis treatments. The majority of patients on dialysis undergo hemodialysis or blood related dialysis. Those patients typically have a device surgically inserted that provides access to the patient's intra-vascular blood volume. That device can be periodically connected to an artificial kidney machine. This process is called hemodialysis. While there are other types of dialysis, hemodialysis is the most common by far.
The number of patients world-wide who receive dialysis or similar measures to survive exceeds two million. Kidney failure is a lethal disease. Still, there are many who suffer from kidney-related issues that do not get the needed treatment, It is estimated that the more than two million patients who receive such dialysis or similar measures probably only account for 10% of the people worldwide that need such dialysis treatment to improve their day to day living circumstances.
Hemodialysis can require surgical devices in certain circumstances. Two classic surgically inserted devices are generally used for hemodialysis. The first type of surgical devices can comprise a venous access catheter that are usually used for short term dialysis access or as a bridge to a more long-term device. The second type of surgical device can comprise long term devices that typically revolve around creating a surgical connection between the patient's artery and vein that allows for high pressure blood to “shunt” rapidly to the low-pressure venous system. This “shunt,” or dialysis access device, allows for high flow and high-volume sampling of the patient's blood and subsequent connection to an artificial kidney machine. Once the blood is cleaned of toxins, the blood is returned to the patient via a second connection to the dialysis access device. dialysis access devices are either artificial or native to the patient (the patient's own vein). All dialysis access devices require native arterial blood (the patient's own) for correct function. While there are multiple potential complications related to dialysis access devices, arterial steal is a complication that can be detrimental to the health of the patient on dialysis.
Arterial steal or vascular access steal syndrome is a syndrome caused by ischemia (not enough blood flow to the patient) resulting from insertion of a dialysis access device. dialysis access devices function by altering the patients native vascular flow. When this flow alteration causes ischemia, it is call vascular access steal syndrome. Options for treatment of vascular access steal syndrome typically involve a surgical procedure to change the blood flow in the dialysis access device and increase the patients native flow, thus relieving the ischemia. In extreme cases, the dialysis access needs to be sacrificed or reversed, which re-directs all the blood flow back to the patient, relieving the ischemia. Such sacrificial or reversal procedures obviously lead to the “loss” of that device as an option for dialysis treatment.
As such, a need exists for a minimally invasive device and treatment for treating vascular access steal syndrome to allow patients who suffer from vascular access steal syndrome and the underlying ischemia to safely continue receiving dialysis.
The present subject matter provides endovascular stents and endovascular device platforms that allows for the modulation/regulation of vascular flow to treat certain disease states. The endovascular device platform can comprise a balloon-stent system that is inserted using minimally invasive techniques. The balloon-stent system can comprise of a dumbbell, stepped or funnel shaped angioplasty balloon with a mounted covered, vascular stent. The angioplasty balloon can be used for inserting, positioning and expanding the vascular stent in a desired vascular structure, such as a vein, artery, or artificial blood vessel. Once inserted, the stent can modulate and even reduce vascular flow. Methods related to the assembly and use of the endovascular stents and endovascular device platforms as disclosed herein are also provided.
Thus, it is an object of the presently disclosed subject matter to provide endovascular stents and endovascular device platforms as well as methods related thereto. While one or more objects of the presently disclosed subject matter having been stated hereinabove, and which is achieved in whole or in part by the presently disclosed subject matter, other objects will become evident as the description proceeds when taken in connection with the accompanying drawings as best described hereinbelow.
A full and enabling disclosure of the present subject matter including the best mode thereof to one of ordinary skill in the art is set forth more particularly in the remainder of the specification, including reference to the accompanying figures, in which:
Repeat use of reference characters in the present specification and drawings is intended to represent the seam or analogous features or elements of the present subject matter.
Reference now will be made to the embodiments of the present subject matter, one or more examples of which are set forth below. Each example is provided by way of an explanation of the present subject matter, not as a limitation. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present subject matter without departing from the scope or spirit of the present subject matter. For instance, features illustrated or described as one embodiment can be used on another embodiment to yield still a further embodiment. It is to be understood by one of ordinary skill in the art that the present discussion is a description of exemplary embodiments only, and is not intended as limiting the broader aspects of the present subject matter, which broader aspects are embodied in exemplary constructions.
Although the terms first, second, right, left, front, back, top, bottom, etc. may be used herein to describe various features, elements, components, regions, layers and/or sections, these features, elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one feature, element, component, region, layer or section from another feature, element, component, region, layer or section. Thus, a first feature, element, component, region, layer or section discussed below could be termed a second feature, element, component, region, layer or section without departing from the teachings of the disclosure herein.
Similarly, when a feature or element is being described in the present disclosure as “on” or “over” another feature or element, it is to be understood that the features or elements can either be directly contacting each other or have another feature or element between them, unless expressly stated to the contrary. Thus, these terms are simply describing the relative position of the features or elements to each other and do not necessarily mean “on top of” since the relative position above or below depends upon the orientation of the device to the viewer.
Embodiments of the subject matter of the disclosure are described herein with reference to schematic illustrations of embodiments that may be idealized. As such, variations from the shapes and/or positions of features, elements or components within the illustrations as a result of, for example but not limited to, user preferences, manufacturing techniques and/or tolerances are expected. Shapes, sizes and/or positions of features, elements or components illustrated in the figures may also be magnified, minimized, exaggerated, shifted or simplified to facilitate explanation of the subject matter disclosed herein. Thus, the features, elements or components illustrated in the figures are schematic in nature and their shapes and/or positions are not intended to illustrate the precise configuration of the subject matter and are not necessarily intended to limit the scope of the subject matter disclosed herein unless it specifically stated otherwise herein.
It is to be understood that the ranges and limits mentioned herein include all ranges located within the prescribed limits (i.e., subranges). For instance, a range from about 100 to about 200 also includes ranges from 110 to 150, 170 to 190, 153 to 162, and 145.3 to 149.6. Further, a limit of up to about 7 also includes a limit of up to about 5, up to 3, and up to about 4.5, as well as ranges within the limit, such as from about 1 to about 5, and from about 3.2 to about 6.5.
The term “thermoplastic” is used herein to mean any material formed from a polymer which softens and flows when heated above certain polymer-dependent elevated temperatures and solidifies when cooled below that temperature; such a polymer may be heated and softened and cooled and solidified a number of times without suffering any basic alteration in characteristics, provided heating is below the decomposition temperature of the polymer. Examples of thermoplastic polymers include, by way of illustration only, polyolefins, polyesters, polyamides, polyurethanes, fluoropolymers, acrylic ester polymers and copolymers, polyvinyl chloride, polyvinyl acetate, etc. and copolymers thereof that are safe to use within a body of a patient.
As used herein, the terms “covered stent” or “vascular covered stent” mean an expandable, flexible, metal tube-shaped device (i.e., stent) that is covered with a fabric or graft material, such as a stretchable thermoplastic material, for example but not limited to, an expandable polytetrafluoroethylene (ePTFE) or a polyester that are safe to use within a body of a patient. Each covered stent is mounted on the end of a delivery catheter system.
As used herein, the term “tubular structure” means a hollow structure that has an inner surface and an outer surface which can have about the same inner diameter and about the same outer diameter or about the same width and about the same height across a length of the tubular structure, such as a cylindrical structure or can have an inner diameter and/or a outer diameter that is varied or widths and heights that are varied along a length of the tubular structure.
As used herein, the term “skeletal frame” means a supportive or protective structure that gives shape and strength to the stent on which stretchable thermoplastic interior cover of a stent can be secured. The skeletal frame may be porous and expandable.
As used herein, the terms “stretchable thermoplastic interior cover” means a fabric such as a nonwoven fabric, film or composite or laminate material that can be used to cover a can be safely used within a body of a patient.
As used herein, the terms “frustoconical shape” or “frustoconical” means a structure or a portion of the structure having the shape of a frustum of a cone or pyramid, for example, having a truncated cone shape or a truncated pyramidal shape.
As used herein, the term “vascular structure” means a vessel within a human body used to transport or circulate blood with the body. The vessel can be natural or artificial and can include, but not limited to human veins or arteries, artificial or synthetic veins or arteries, and dialysis access device.
The present subject matter relates to endovascular devices and endovascular device systems and related methods that allow for the modulation/regulation of vascular flow. In particular, the present subject matter relates to endovascular stents and endovascular device systems and related methods that allow for the modulation and/or regulation of vascular flow to treat certain disease states.
The present subject matter provides endovascular stents and endovascular device platforms. can comprise a balloon-stent system that is inserted using minimally invasive techniques. The balloon-stent system can comprise of a dumbbell, stepped or funnel shaped angioplasty balloon with a mounted covered, vascular stent. The angioplasty balloon is used for inserting, positioning and expanding the vascular stent in a desired blood vessel. Once inserted, the stent will modulate and even reduce vascular flow. Methods related to the manufacture and use of the endovascular stents and endovascular device platforms as disclosed herein are also provided.
A dumbbell or funnel shaped balloon with a mounted covered stent can be inserted into a vascular structure with the balloon being inflated to expand the stent and then deflated for removal leaving the stent within the vascular structure to alter vascular flow and specifically reduce blood flow. Poiseuille's formula states that flow can be reduced in a tube that carries a fluid by reducing the diameter (the Poiseuille's formula express the discharged streamlined volume flow through a smooth-walled circular pipe: v=πp r 4/8η|(1) v=discharge volume flow (m 3/s) p=pressure difference between the ends of the pipe (n/m 2, pa). In short, reduction in the radius of a pipe, i.e., a vascular structure like a dialysis access device, can lead to a reduction in flow within that device to treat disease states such as vascular access-induced steal syndrome (VASS). VASS can be an uncommon but challenging complication that occurs due to a functioning arteriovenous (AV) fistula or graft in 6% of chronic kidney disease patients who require hemodialysis. In the case of VASS, the expanded stent can treat patient ischemia. Importantly, the device could be reversed (if needed) with an additional endovascular procedure. The endovascular device platform can comprise a 2-part system that includes a balloon expandable endovascular covered stent, meeting diameter specifications specific to dialysis grafts and a dumbbell-shaped, stepped, or funnel-shaped delivery balloon that will expand both edges of the stent flush to the vessel wall, while leaving a tapered, funnel-shaped opening at the center (an hour-glass shape) to limit the blood flow through the stent, thus slowing the flow enough to alleviate the aforementioned ischemia caused by VASS. A function of the installed stent relies on redirecting some of the patient's vascular flow to the dialysis access device. Too much flow from the artery to the vein via the dialysis access device will lead to ischemia or steal. Once installed, the covered stent with the reduced flow shape can alter, modulate, or restrict blood flow to treat ischemia.
Other disease states that will likely benefit from endovascular devices and endovascular device systems and related methods discussed herein. Specifically, congestive heart failure and inherited or acquired arterio-venous fistula/malformations.
Referring to
For example, in some embodiments, the first inner diameter ID1 of a first end portion 24 and a second inner diameter ID2 of a second end portion 28 can be about 10% to about 70% larger in diameter than the third inner diameter ID3 within a center portion 30 of the tubular structure 20. In some embodiments, the first inner diameter ID1 of a first end portion 24 and a second inner diameter ID2 of a second end portion 28 can be about 25% to about 60% larger in diameter than the third inner diameter ID3 within a center portion 30 of the tubular structure 20. In some embodiments, the first inner diameter ID1 of a first end portion 24 and a second inner diameter ID2 of a second end portion 28 can be about 30% to about 55% larger in diameter than the third inner diameter ID3 within a center portion 30 of the tubular structure 20. In some embodiments, the first inner diameter ID1 of a first end portion 24 and a second inner diameter ID2 of a second end portion 28 can be about 40% to about 50% larger in diameter than the third inner diameter ID3 within a center portion 30 of the tubular structure 20. For instance, in some embodiments, the first inner diameter ID1 of a first end portion 24 and a second inner diameter ID2 of a second end portion 28 can be about 50% larger in diameter than the third inner diameter ID3 within a center portion 30 of the tubular structure 20.
The tubular structure 20 can comprise a first intermediate portion 34 between the first end portion 24 and the center portion 30 and a second intermediate portion 36 between the second end portion 28 and the center portion 30. For example, the first and second intermediate portions 24, 28 each can have a truncated cone shape. For instance, the first and second intermediate portions 24, 28 each can have a frustoconical shape. In particular, the first intermediate portion 34 can gradually narrow from the first inner diameter ID1 of the first end portion 24 to the third inner diameter ID3 of the center portion 30. Similarly, the second intermediate portion 36 can gradually narrow from the second inner diameter ID2 of the second end portion 28 to the third inner diameter ID3 of the center portion 30 to facilitate laminar flow of blood passing through the stent 10 once the stent is installed.
In some embodiments, the tubular structure 20 of the covered stent 10 can comprise a skeletal frame 14 configured in a tubular shape and having an exterior 14A and an interior 14B. The skeletal frame 14 can comprise a metal. For example, in some embodiments, the skeletal frame can be braided metal wire. For example, in some embodiments, the skeletal frame 14 can comprise a stainless steel. In some embodiments, the skeletal frame 14 can comprise a wire mesh that can be expanded to the installed shape 12 of the covered stent 10. In some embodiments, the skeletal frame 14 can comprise a braid of metal wires.
Further, the tubular structure 20 of the covered stent 10 can also comprise a stretchable interior cover 16 configured to the interior 14B of the skeletal frame 14 that forms an interior surface 20B of the tubular structure 20. In particular, once the interior surface is expanded to its installed shape 12, the interior surface 20B can comprise different interior surface sections that can have the same surface structure but different orientations and positions within the covered stent 10. For example, the interior surface 20B can comprise a first interior surface section 20B1 in the first end portion 24 and a second interior surface section 20B2 in the second end portion 28 in the cover stent 10 that are circumferential in nature. Similarly, the interior surface 20B can comprise a sloping, or tapering, third interior surface section 20B3 in the first intermediate portion 34 and a fourth sloping, or tapering, interior surface section 20B4 in the second intermediate portion 36 in the cover stent 10, while having a smaller circumferential fifth interior surface section 20B3 in the center portion 30 of the covered stent 10. Thus, the interior surface section 20B1-20B3 can have different profiles as shown in
Portions of tubular structures are provided in
In the installed shape 12, the different portions of the tubular structure 20 can have different shapes to provide different features to the function of the covered stent 10. For example, the first end portion 24 of the tubular structure 20 of the covered stent 10 can have a hollow cylindrical shape 22 that is defined by the first inner diameter ID1 as measured from the interior surface section 20B1 of the tubular structure 20 within the first end portion 24. Similarly, the second end portion 28 can have a hollow cylindrical shape 26 that is defined by the second inner diameter ID2 as measured from the interior surface section 20B2 of the tubular structure 20 within the second end portion 28. The first and second end portions 24, 28 can provide the exterior surface portions that abut against the walls of the vascular structure VS to provide a surface for grafting the cover stent 10 to the vascular structure VS and anchoring the cover stent 10
To restricts blood flow through the tubular structure 20 of the covered stent 10 in the vascular structure in which the stent 10 is placed, the third inner diameter ID3 of the center portion 30 is less than the first inner diameter ID1 and the second inner diameter 28. To facilitate laminar blood flow through the cover stent 10 as well as on the down flow side of the covered stent 10, the first and second intermediate portions 34, 36 each having a frustoconical shape 38A, 38B. For example, the interior surface 20B of the tubular structure 20 in the first intermediate portion 34 can taper from the interior surface 20B of tubular structure 20 at the first inner diameter ID1 of the first end portion 24 to the interior surface 20B of the tubular structure 20 at the third inner diameter ID3 of the center portion 30. Similarly, the interior surface 20B of the tubular structure 20 in the second intermediate portion 36 can taper from the interior surface 20B of tubular structure 20 at the second inner diameter ID2 of the second end portion 28 to the interior surface 20B of the tubular structure 20 at the third inner diameter ID3 of the center portion 30. These tapered walls of the first and second intermediate portions 34, 36 each can have an angle of slope α1, α2 of the interior surfaces 20B in the respective first and second intermediate portions 34, 36 as measured from a centerline axis CL of the tubular structure 20 that extends along the length LTS. These angles of slope α1, α2 can be gradual enough in their steepness to facilitate laminar flow of blood passing through the covered stent 10.
In particular, to facilitate laminar flow of blood passing through the covered stent 10, the first intermediate portion 34 can gradually narrow from the first inner diameter ID1 of the first end portion 24 to the third inner diameter ID3 of the center portion 30. Similarly, the second intermediate portion 28 can gradually narrow from the second inner diameter ID2 of the second end portion 28 to the third inner diameter ID3 of the center portion 30 to facilitate laminar flow of blood passing through the covered stent 10. To provide for the gradual narrowing, the first and second intermediate portions can comprise a substantial portion of the length LTS of the tubular structure 20. For example, in some embodiments, the first intermediate portion 34 and the second intermediate portion 36 of the tubular structure 20 each can comprise between about 15% of the length Ls of the tubular structure 20 and about 33% of the length LTS of the tubular structure 20. For instance, in some embodiments, the first intermediate portion 34 and the second intermediate portion 36 of the tubular structure 20 each can comprise about 20% of the length of the tubular structure.
To also facilitate laminar flow of the blood through the covered stent 10, for example, in some embodiments, the center portion 30 can comprise between about 13% of the length LTS of the tubular structure 20 and about 40% of the length LTS of the tubular structure 20. In some embodiments, the center portion 30 of the tubular structure 20 can comprise about 30% of the length LTS of the tubular structure 20.
As stated above, the tubular structure 20 can be expandable. For example, the tubular structure 20 of the covered stent 10 can be expandable from a uniform tubular structure to the installed shape 12 using a catheter and balloon. More particularly, as shown in
The covered stent 10 can be installed in a variety of different vascular structures VS. For example, the vascular structure VS can comprise at least one of a vein or artery with the patient. Additionally, the vascular structure VS can comprise a synthetic vascular structure not native to the patient. For example, the vascular structure VS can comprise a dialysis access device for use in hemodialysis.
As shown in
As described above, upon inflation of the angioplasty balloon 44 and installation of the covered stent 10, the tubular structure 20 comprises a first intermediate portion 34 between the first end portion 24 and the center portion 30 and a second intermediate portion 36 between the second end portion 28 and the center portion 30 with the first and second intermediate portions 34, 36 each having a frustoconical shape. In particular, the first intermediate portion 34 can gradually narrow from the first inner diameter ID1 of the first end portion 24 to the third inner diameter ID3 of the center portion 30 and the second intermediate portion 36 can gradually narrow from the second inner diameter ID2 of the second end portion 28 to the third inner diameter ID3 of the center portion 30 on the other side of the stent 10 to facilitate laminar flow of blood passing through the stent 10.
The expanded stent 10 can be helpful in treating ischemia within a dialysis patient. The vascular structure VS can comprise a dialysis access device. The expanded tubular structure 20 of the covered stent 10 can also have a first outer diameter OD1 of the first end portion 24 and a second outer diameter OD2 of the second end portion 28. Upon installation within the vascular structure VS of the dialysis access device, the first outer diameter OD1 of the first end portion 24 of the tubular structure 20 and the second outer diameter OD2 of the second end portion 28 of the tubular structure 20 meet diameter specifications specific to dialysis grafts so that the covered stent 10 will graft to the vascular structure VS of the dialysis access device to hold the covered stent 10 in place. Once in place in the vascular structure VS of the dialysis access device, the third inner diameter ID3 of center portion 30 is such that the third inner diameter ID3 reduces flow of blood within the dialysis access device to treat ischemia within the dialysis patient.
As described above, the unexpanded tubular structure 20′ that has a uniform hollow cylindrical shape can comprise the skeletal frame 14 configured in a uniform tubular shape and having the exterior 14A and the interior 14B and a stretchable thermoplastic interior cover 16 configured to the interior 14B of the skeletal frame 14 that forms an interior surface 20B′ of the tubular structure 20′. The skeletal frame 14 and the internal cover 16 are expandable. In some embodiments, the skeletal structure 14 can comprise a metal such as a wire braid for example. In some embodiments, the stretchable thermoplastic interior cover 16 can comprise polytetrafluoroethylene. In some embodiments, the stretchable interior cover 16 can comprise a polyester.
Once the angioplasty balloon 44 has been inflated and expanded the tubular structure 20 so that he the covered stent 10 is in the installed shape 12, the first end portion 24 of tubular structure 20 has a hollow cylindrical shape with the first inner diameter ID1 as measured from the interior surface 14B of the tubular structure 20 generally uniformly throughout the first end portion 24. Similarly, the second end portion 28 can have a hollow cylindrical shape with the second inner diameter ID2 as measured from the interior surface 14B of the tubular structure 20 throughout the second end portion 28. As outlined above, the center portion 30, which can also have a hollow cylindrical shape, along the length between the first end portion 24 and the second end portion 28 with the third inner diameter ID3 at the center portion 30 being less the first inner diameter ID1 and the second inner diameter ID2 such that the third inner diameter ID3 at the center portion 30 restricts blood flow in the dialysis access device in which the stent 10 is placed. As above, when the balloon 44 is inflated, the shape of the balloon 44 with the inward sloping, or tapering, first and second heads 46A, 48A also expands the tubular structure to have the first intermediate portion 34 between the first end portion 24 and the center portion 30 and a second intermediate portion 36 between the second end portion 28 and the center portion 30. The first and second intermediate portions 36 and 38 can each have a frustoconical shape with the interior surface 20B of the tubular structure 20 in the first intermediate portion 34 tapering from the interior surface 20B of tubular structure 20 at the first inner diameter ID1 of the first end portion 24 to the interior surface 20B of the tubular structure 20 at the third inner diameter ID3 of the center portion 30 and the interior surface 208 of the tubular structure 20 in the second intermediate portion 36 tapering from the interior surface 20B of tubular structure 20 at the second inner diameter ID2 of the second end portion 28 to the interior surface 20B of the tubular structure 20 at the third inner diameter ID3 of the center portion 30.
Thus, as shown in
Once the dialysis access device VS is located and the patient is prepared for the installation of the stent, the stent-balloon catheter 50 can be inserted into the body of the patient at an entry point. Depending on the location of the dialysis access device VS1, the stent-balloon catheter 50 can be inserted into a dialysis access device VS1 within a patient through the arm for example. In other embodiments of the method, the stent-balloon catheter 50 can be inserted at another entry point and maneuvered through the circulatory system to the dialysis access device VS1. Once in the dialysis access device VS1, the stent-balloon catheter 50 is positioned in the dialysis access device VS1 within a patient in a position where restriction of blood flow is desired.
The angioplasty balloon 44 of the stent-balloon catheter 50 is then inflated to expand the unexpanded tubular structure 20′ of the covered stent 10. The angioplasty balloon 44 can have a dumbbell shape when inflated with a first head 46A on a first end 46 of the angioplasty balloon 44 having a first outer diameter OB1 and a second head 48A on a second end 48 of the angioplasty balloon 44 having a second outer diameter OB2 and a narrow center portion 49 having a third outer diameter OB3 that is less than the first outer diameter OB1 of the first end 46 and the second outer diameter OB2 of the second end 48. Thus, when the angioplasty balloon 44 is inflated, the covered stent 10 is expanded into an installed dumbbell shape 12 having a first inner diameter ID1 of a first end portion 24 of the tubular structure 20 and a second inner diameter ID2 of a second end portion 28 of the tubular structure 28 that are larger than a third inner diameter ID3 within a center portion 30 of the tubular structure 20 with the first and second end portions 24, 28 being flush against wall segments WS of the dialysis access device VS.
The angioplasty balloon 44 of the balloon catheter 40 can be deflated and the catheter 40 can be removed from the installed covered stent 10 and the dialysis access device VS1 leaving the covered stent 10 in place in a position to restrict blood flow within the dialysis access device VS1 to treat ischemia within the patient.
Once installed, the covered stent 10 has the benefit of being able to be expanded to permit increased blood flow if complication due to the restricted blood flow arises. For example, the covered stent 10 can be installed as described above with the catheter 40 removed and the exterior surface 14A of the first and second end portions 24, 28 of the covered stent 10 are grafted into the vascular structure, such as the dialysis access device VS1. If the third inner diameter ID3 of the center portion 30 of covered stent 10 causes a restriction in the blood flow that interferes with the hemodialysis process or causes circulatory problems or pain in the patient, then the third inner diameter ID3 of the center portion 30 of covered stent 10 can be expandable using a different expansion catheter 52 from the catheter 40 used to install the covered stent 10 in its installed shape 12 as shown in
In some embodiments of a method of expanding the third inner diameter ID3 of the center portion 30 of covered stent 10, the expansion catheter 52 can be inserted into the vascular structure, such as the dialysis access device VS1 shown in
Thus, as disclosed herein, a method for restricting blood flow within a vascular structure using an endovascular stent-balloon system is provided. A stent-balloon catheter can be provided and can comprise a shaft and an angioplasty balloon on a portion of the shaft and an expandable covered stent comprising an unexpanded tubular structure that is mounted on the uninflated angioplasty balloon. The angioplasty balloon can have a dumbbell shape when it is inflated with a first head on a first end of the angioplasty balloon having a first outer diameter and a second head on a second end of the angioplasty balloon having a second outer diameter and a narrow center portion having a third outer diameter that is less than the first outer diameter of the first end and the second outer diameter of the second end.
The stent-balloon catheter can be positioned in a vascular structure within a patient in a position where restriction of blood flaw is desired. The angioplasty balloon of the stent-balloon catheter can be inflated such that the covered stent is expanded into an installed dumbbell shape having a first inner diameter of a first end portion of the tubular structure and a second inner diameter of a second end portion of the tubular structure that are larger than a third inner diameter within a center portion of the tubular structure between the first and second end portions. The stent and the balloon catheter can be sized and/or selected to fit within the vascular structure of the patient so that, when the angioplasty balloon is inflated the stent secured in position within the vascular structure. Once the stent is expanded and secured within the vascular structure, the angioplasty balloon of the stent-balloon catheter can be deflated. The stent-balloon catheter can then be removed from the vascular structure leaving the covered stent in place in a position to restrict blood flow within the vascular structure within the patient.
These and other modifications and variations to the present subject matter may be practiced by those of ordinary skill in the art, without departing from the spirit and scope of the present subject matter, which is more particularly set forth herein above and any appending claims. In addition, it should be understood the aspects of the various embodiments may be interchanged either in whole or in part. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only, and is not intended to limit the present subject matter.
