Patent Application
20220331552
The present invention relates generally to a guide, aspiration or distal access catheter shaft design that is used for neuro vascular applications. In particular, the catheter shaft provides excellent distal flexibility, proximal stability for tracking inside the neuro vasculature, superior external lubricity, and superior interior lubricity for implant delivery.
Almost every neurovascular device placement or therapy takes place in or above the neck. Thus, catheters used inside a neuro vasculature must be able to transverse very tortuous anatomies. Such catheters must be designed to have a superior torquability and anti-kink characteristics within the catheter shaft, a flexible distal portion for reaching intended treatment location and to deliver the therapy without damaging the surrounding vessels. This requires a delicate balance between having the smallest possible outside profile and the largest possible internal lumen for delivery of a medical implant, movement of other catheters inside the lumen for aspiration to reperfusion occluded vessels. In addition, such a catheter must also be visibility under fluoroscopy.
In the design of catheters for neurovascular applications, the engineer must balance between functionality and construction with fundamental targets on catheter trackability, flexibility, pushability and torquability (transmittance or torsional force).
PTFE material offers excellent wear and abrasion resistance with supreme lubricity making it an ideal choice for the inner wall of the catheter. The smooth interior luminal surface of the PTFE liner reduces friction between medical device and catheter as the device is pushed through the tight confines of the catheter lumen. Dip coating and extrusion are two common manufacturing method for making PTFE liner. The Dip coating process is one method used for attaining a PTFE liner. This process can be performed onto a mandrel as part of the catheter shaft construction process. Once the coating has cured, the additional components of the catheter, for example, the nylon jacketing, braiding are built upon the cured dip-coated mandrel. Dip-coating, while appearing to be a simple process at the outset, has some limitations. Dip coating can experience unevenness resembling the surface of an orange peel. Sometimes, dip-coated surfaces can have the appearance of many cross-sectional lines called chatter resulting from vibrations during the coating process. Dip-coated surfaces can also have craters, depressions, or even holes in the cured layers caused by contaminants—including moisture—during the coating process. All these defects will have a negative impact on interior lubricity of the catheter lumen and therefore gravely impede catheter's use. While these defects can be addressed in different ways, the superior precision of the dip-coating process will typically entail greater cost and time.
Extruded PTFE tubing is another method of manufacturing PTFE catheter inner liner. Although extruded PTFE has the lowest coefficient of friction, a typical extruded PTFE tubing has a wall thickness of around 0.001″. This wall thickness could lead to an overall increase in stiffness of the catheter, which is not ideal for traveling through the tortuous path of the neuro vasculature.
An ideal catheter for neurovascular application should have a minimum outer diameter for traveling through small vasculature, and a maximum internal diameter for delivery medical device/implant. This inevitably leads to a need for an ultra-thin catheter inner liner. However, with an ultra-thin catheter inner liner, the engineer will need to incorporate a shaft support component, such as metal wire layer covering the inner catheter liner either in braid profile or in coil profile, to enhance pushability and the kink resistance of the catheter. Minimum contact pressure is required between the metal wire layer and the inner catheter liner in order to maintain the integrity of the catheter construction. Often times, such minimum contract pressure leads to an increase in interior surface roughness of the inner catheter liner (20), and significantly reduce the interior surface lubricity.
Thus there is a need to develop a catheter for neurovascular application which will satisfy the goal of elevated pushability, trackability, flexibility, and torquability, but also a large lumen is needed to achieve maximized aspiration flow; a smaller outside diameter to allow the catheter to track into smaller vessels without posing additional vessel damage to the target treatment location; outer surface lubricity; and a supreme interior surface lubricity to reduce the deployment force.
An aspect of the present teachings provides a catheter shaft for delivering and deploying a medical device. The catheter shaft comprises an ultra-thin inner catheter liner, a first coil middle layer, a second braid middle layer, and an outer jacket layer. The first coil middle layer is made of a flat wire with a width to thickness ratio of at least 2:1. The outer jacket layer is made of materials comprising a soft durometer material forming a distal portion of the outer jacket, a medium durometer material forming a middle portion of the outer jacket, and a strong durometer material forming a proximal portion of the outer jacket.
One embodiment of the present teachings provides that the inner catheter liner of the catheter shaft has an outer diameter to thickness ratio of at least 10:1. The inner catheter liner has a minimum inner diameter of 0.8 mm. One embodiment of the present teachings provides that the first coil middle layer of the catheter shaft has a maximum thickness of 0.06 mm. Another embodiment of the present teachings provides that the first coil middle layer of the catheter shaft has a minimum width of 0.08 mm.
One embodiment of the present teachings provides that the first coil middle layer of the catheter shaft covers at least 30% area of an exterior luminal surface of the inner catheter liner. In another embodiment, depending on the desired stiffness, the coverage area between the first coil middle layer of the catheter shaft over the exterior luminal surface of the inner catheter line ranges between 30-75%. One skilled in the art should understand that the less the coverage area between the first coil middle layer and the inner catheter liner, the more flexible the overall catheter.
One embodiment of the present teachings provides that the second braid middle layer (40) of the catheter shaft has a maximum thickness of 0.03 mm.
One embodiment of the present teachings provides that the inner catheter liner and the outer jacket layer of the catheter shaft are of the same length. Another embodiment of the present teachings provides the first coil middle layer and the second braid middle layer are encapsulated inside both the inner catheter liner and the outer jacket layer.
One embodiment of the present teachings provides that the outer jacket layer bonds with the inner catheter liner through a gap between the wires forming the first coil middle layer (30) and the second braid middle layer.
One embodiment of the present teachings provides that the first coil middle layer of the catheter shaft is made of at least two wires wound in a same direction. Another embodiment of the present teachings provides that the first coil middle layer of the catheter shaft is made of at least two wires wound in an opposite direction.
One embodiment of the present teachings provides that the second braid middle layer (40) placed in between the first coil middle layer and the outer jacket layer. Another embodiment of the present teachings provides that the second braid middle layer is placed over at least a proximal and a middle portion of the first coil middle layer. Another embodiment of the present teachings provides that the second braid middle layer is at least 20 mm shorter than the first coil middle layer.
One embodiment of the present teachings provides that the catheter shaft has an outer diameter to an inner luminal dimeter ratio of at least 1.2:1.
Certain specific details are set forth in the following description and figures to provide an understanding of various embodiments of the present teachings. Those of ordinary skill in the relevant art would understand that they can practice other embodiments of the present teachings without one or more of the details described herein. Thus, it is not the intention of the applicant(s) to restrict or in any way limit the scope of the appended claims to such details. While various processes are described with reference to steps and sequences in the following disclosure, the steps, and sequences of steps should not be taken as required to practice all embodiments of the present teachings.
As used herein, the term “lumen” means a canal, a duct, or a generally tubular space or cavity in the body of a subject, including veins, arteries, blood vessels, capillaries, intestines, and the like. The term “lumen” can also refer to a tubular space in a catheter, a sheath, a hollow needle, a tube, or the like.
As used herein, the term “proximal” shall mean close to the operator (less into the body) and “distal” shall mean away from the operator (further into the body). In positioning a medical device inside a patient, “distal” refers to the direction relatively away from a catheter insertion location and “proximal” refers to the direction relatively close to the insertion location.
As used herein, the term “wire” can be a strand, a cord, a fiber, a yarn, a filament, a cable, a thread, or the like, and these terms may be used interchangeably.
As used herein, the term “sheath” may also be described as a “catheter” and, thus, these terms can be used interchangeably.
Unless otherwise specified, all numbers expressing quantities, measurements, and other properties or parameters used in the specification and claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless otherwise indicated, it should be understood that the numerical parameters set forth in the following specification and appended claims are approximations. At the very least and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, numerical parameters should be read in light of the number of reported significant digits and the application of ordinary rounding techniques.
It will be understood that the words “comprising” (and any form of comprising, such as “comprise” and “comprises”), “having” (and any form of having, such as “have” and “has”), “including” (and any form of including, such as “includes” and “include”) or “containing” (and any form of containing, such as “contains” and “contain”) when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
It will be further understood that, although the terms first, second, third, etc. may be used herein to describe various limitations, elements, components, regions, layers and/or sections, these limitations, elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one limitation, element, component, region, layer or section from another limitation, element, component, region, layer or section. Thus, a first limitation, element, component, region, layer or section discussed below could be termed a second limitation, element, component, region, layer or section without departing from the teachings of the present application.
It will be further understood that when an element is referred to as being “on”, “attached”, “connected” or “coupled” to another element, it can be directly on or above, or connected or coupled to, the other element or one or more intervening elements can be present. In contrast, when an element is referred to as being “directly on”, “directly attached”, “directly connected” or “directly coupled” to another element, there are no intervening elements present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g. “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.).
It will be further understood that when a first element is referred to as being “in”, “on” and/or “within” a second element, the first element can be positioned: within an internal space of the second element, within a portion of the second element (e.g. within a wall of the second element); positioned on an external and/or internal surface of the second element; and combinations of one or more of these.
Spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like may be used to describe an element and/or feature's relationship to another element(s) and/or feature(s) as, for example, illustrated in the figures. It will be further understood that the spatially relative terms are intended to encompass different orientations of the device in use and/or operation in addition to the orientation depicted in the figures. For example, if the device in a figure is turned over, elements described as “below” and/or “beneath” other elements or features would then be oriented “above” the other elements or features. The device can be otherwise oriented (e.g. rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
The terms “reduce”, “reducing”, “reduction” and the like, where used herein, are to include a reduction in a quantity, including a reduction to zero. Reducing the likelihood of an occurrence shall include prevention of the occurrence.
The term “and/or” where used herein is to be taken as specific disclosure of each of the two specified features or components with or without the other. For example “A and/or B” is to be taken as specific disclosure of each of (i) A, (ii) B and (iii) A and B, just as if each is set out individually herein.
The term “diameter” where used herein to describe a non-circular geometry is to be taken as the diameter of a hypothetical circle approximating the geometry being described. For example, when describing a cross-section, such as the cross-section of a component, the term “diameter” shall be taken to represent the diameter of a hypothetical circle with the same cross-sectional area as the cross-section of the component being described.
The terms “major axis” and “minor axis” of a component where used herein are the length and diameter, respectively, of the smallest volume hypothetical cylinder which can completely surround the component.
It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination. For example, it will be appreciated that all features set out in any of the claims (whether independent or dependent) can be combined in any given way.
The present teaching relates to a catheter shaft having a single lumen, large-bore, and a thin catheter wall. According to one embodiment of the present teaching, the disclosed catheter configuration offers excellent distal flexibility, an outstanding proximal pushability and torquability, superior external lubricity, and superior internal surface lubricity.
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According to one embodiment of the present teaching, the catheter shaft (10) assembly has a general length of 1100-1400 mm, an outer diameter of 1.4-2.7 mm, an inner lumen diameter of 1.2-2.3 mm. One skilled in the art should understand that overall length and size of the catheter shaft (10) assembly could be easily modified to fit for a specific application. Thus, the number disclosed herein should be considered as a reference, and should not be viewed as limiting to the scope of the claim.
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According to one embodiment, the internal luminal surface of the inner layer (20) of the catheter shaft (10) directly contacts a medical device/implant as it travels through the catheter. Thus the internal luminal surface of this inner layer (20) of the catheter shaft (10) is designed to provide sufficient lubricity which minimizes a force required to push the device/implant through the catheter lumen (21).
According to one embodiment, the inner layer (20) of the catheter shaft (10) is made of extruded PTFE (polytetrafluoroethylene). In another embodiment, the inner layer (20) of the catheter shaft (10) is made of expanded PTFE, also known as ePTFE. ePTFE inner catheter liner (20) is made by expanding PTFE tubing carefully using a non-standard manufacturing process such as heating an extruded PTFE tube to the desired temperature followed by enlarge its inner diameter over a core mandrel. Such a post-extrusion process will produce an enlarged inner tube diameter and an ultrathin tubular wall with microscopic pores. The resulted ePTFE inner catheter liner (20) has the physical character of air-permeable, soft & flexible, and feels somewhat like smooth, spongey, like a membrane. The resulted ePTFE inner catheter liner (20) also has the character of high linear strength, chemically inert, remains watertight at low pressure, has a low dielectric constant, and offers excellent radial expansion and UV resistance.
One skilled in the art should understand that although extruded PTFE and expanded PTFE (ePTFE) tubing have been described here for the purpose of explaining present teaching, the inner layer (20) of the catheter shaft (10) could be made with other material, such as FEP (fluorinated ethylene propylene), FEP (fluorinated ethylene propylene), HDPE (high-density polyethylene), LDPE (low-density polyethylene), Polyethylene terephthalate (PET), Polypropylene (PP), Polyamides/Pebax, with any manufacturing process known in the field such as direct extrusion and/or post extrusion axial stretching and/or radial expansion in order to achieve an ultra-thin luminal wall.
In an alternative embodiment of the present teaching, the inner layer could be made of two materials joined together. For example, a distal portion of the inner layer could be made of polyurethane tubing while the rest portion of the inner layer is made of extruded PTFE. The extruded PTFE provides the catheter shaft with pushability, and the polyurethane distal portion provides the catheter shaft with flexibility and soft distal tip to better tracking insider the neurovasculature. According to one example embodiment, the distal polyurethane portion of the inner layer could be made of polyurethane tube with a luminal wall thickness of 0.013 mm-0.025 mm (or 0.0005″ to 0.001″). Such distal polyurethane tubing then joins to the rest of the PTFE portion by thermal sealing, or other known method in the field. Although polyurethane and PTFE combination are disclosed here as one exemplary inner layer construction, one skilled in the art should understand that other material combination could be incorporated to achieve the design purpose of the present teaching which is an inner layer of the catheter shaft with ultra-thin luminal wall and a smooth and lubricate inner luminal surface in order to provide a good tractability for minim invasive procedure.
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One skilled in the art should understand
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According to one embodiment, and as shown in
According to another embodiment of the present teaching, the first middle layer (30) is a helical coil (31) with a constant pitch. According to another embodiment of the present teaching, the wire (100) forming the coil middle layer (30) has a constant thickness and a constant width throughout its entire length. Yet in another embodiment of the present teaching, in order to achieve a desired steerability of the catheter shaft (10) while achieving a greater flexibility at the distal section of the catheter shaft (10), the helical coil (31) could have a smaller pitch at a proximal portion of the catheter shaft (10), and a greater pitch at a distal portion of the catheter, and a gradual change in between. In Another embodiment of the present teaching, while the thickness of the wire remaining the same, the wire (100) forming the helical coil (31) has a greater width at a proximal portion of the catheter shaft (10), and a smaller width profile at a distal portion of the catheter shaft (10), and a gradual change in between. Thus, a specific embodiment explained and illustrated herein used to limit the scope of the present teaching.
One skilled in the art should understand that comparing to round wire coil, the flat wire coil, when the flat wire having the same cross sectional area as the round wire, offers at least the same kink resistance as the round wire coil, but with at least a 33% reduction in the overall wall thickness profile. Thus the embodiment in present teaching provide a minimum increase in catheter radial profile. In another word, the present teaching offers a largest possible inner catheter lumen size while keeping the outer radial catheter profile as minimum as possible.
According to one embodiment, the flat wire that forms the coil middle layer (30) could be formed with Stainless Steel, Tungsten, Cobalt Chromium Alloys, and others. In another embodiment, the flat wire (100) that forms the coil middle layer (30) could be formed with super elastic material such Nitinol. In one embodiment, Nitinol could allow the coil middle layer (30) to recover its pre-configured circular lumen shape even when catheter is kinked during use.
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According to one embodiment of the present teaching, the second middle layer (40) is placed over the exterior of the first coil middle layer (30), as illustrated in
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According to one embodiment, the outer jacket layer (50) is made of a single material, such as nylon or PEBAX, having a constant durometer. According to another embodiment of present teaching, the outer jacket layer (50) has a durometer of 25-80 shore D, a length of 20-500 mm, an outer diameter of 2.0-2.5 mm, and a wall thickness of 0.025-0.13 mm. According to one embodiment, the outer jacket layer (50) covers the entire length of the two middle layers (30, 40) and the entire length of the inner layer (20) of the catheter shaft (10).
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According to another embodiment of the present teaching, additional coating layer can be added to the catheter construct described in the present teaching. For example, a hydrophilic coating in order to achieve a smooth and slippery surface, which allows the catheter to track in the vasculature with ease.
Although not specifically described in the above disclosure, one skilled in the art should understand that one or more radiopaque markers are used to aid visualization through imaging devices such as fluoroscope; X-ray; CT scanner; MRI; ultrasound imager. A marker, as disclosed herein, can be applied to any part of the catheter shaft (10) of the present teachings. A radiopaque marker can be, adhered, swaged, crimped, otherwise placed, and secured in or on the catheter shaft (10). The radiopaque marker may be made of tantalum, tungsten, platinum, iridium, gold, or alloys of these materials or other materials that are known to those skilled in the art. The radiopaque marker can also be made of numerous paramagnetic materials, including one or more elements with atomic numbers 21-29, 42, 44, and 58-70, such as chromium (III), manganese (II), iron (III), iron (II), cobalt (II), copper (II), nickel (II), praseodymium (III), neodymium (III), samarium (III), ytterbium (III), gadolinium (III), terbium (III), dysprosium (III), holmium (III) and erbium (III), or other MR visible materials that are known to those skilled in the arts.
One skilled in the art should understand, although most exemplary embodiments described above refer to a catheter shaft (10) used for neuro vasculature application, exemplary embodiments of the present teaching could be used in any other suitable minimum invasive application. For example, the exemplary embodiments of the present teaching could be used to deliver vaso-occlusive devices, stents, aspiration, stent retrievers for ischemic stroke, and etc. In another example, an exemplary embodiment of the present teaching could be used to precisely deliver an implant into an aneurysm, such as a brain aneurysm. In another example, the exemplary embodiment of the present teaching could be used to precisely delivery an implant into a blood vessel such as a blood vessel of the brain, a patent blood vessel, or other locations.
The foregoing description and accompanying drawings set forth a number of examples of representative embodiments at the present time. Various modifications and alternative designs will become apparent to those skilled in the art in light of the foregoing teachings without departing from the spirit hereof, or exceeding the scope hereof, which is indicated by the following claims rather than by the foregoing description. All changes and variations that fall within the meaning and range of equivalency of the claims are to be embraced within their scope.
This application is a PCT application which claims priority to and the benefit of U.S. Provisional Patent Application Ser. No. 62/886,322, entitled “Multi-layer Catheter Construction,” filed Aug. 13, 2019. The entirety of the U.S. Provisional Application Ser. No. 62/886,322 is incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2020/045943 | 8/12/2020 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 62886322 | Aug 2019 | US |
