Microcatheter with multi-strand braided structure

Abstract

A suitable microcatheter is provided, featuring a multi-strand braided structure. [Solution] The microcatheter includes a long shaft having a distal end and a proximal end. The long shaft includes an outer layer formed from a polymer and an intermediate layer formed from a braid having a plurality of strands 42, each having four filaments 44, the four filaments being circular metal having an outer diameter of less than 0.0009 inches (0.023 mm). The braid may have a surface area coverage of at least 70%. The long shaft includes an inner layer formed from a polymer and a distal polymer tip attached to the distal end of the long shaft.

Description

Technical Field

[0001] The present invention generally relates to a catheter for delivering a therapeutic agent or device to a site within a body lumen. More particularly, the present invention relates to a microcatheter used to guide the vasculature.

Background Art

[0002] A variety of intravascular catheters are known that include small-diameter catheters having a penetrating central lumen configured for use in smaller vascular structures. Such catheters are known as microcatheters. Microcatheters are typically highly flexible and thin-walled, which can limit torque transmission from the proximal hub to the distal tip, reduce kink resistance, and make it difficult to pass through a tortuous vasculature. Microcatheters may also have a limited ability to withstand rupture, particularly where the microcatheter is subjected to kinking or sharp angled bends and fluid is passing through the central lumen. There is still a need for improved microcatheters that enhance torque transmission, burst pressure resistance, pushability, and kink resistance.

[0003] There is a continuing need to provide alternative medical devices, as well as alternative methods of manufacturing and using medical devices.

Summary of the Invention

[0004] This disclosure provides designs, materials, manufacturing methods, and alternative uses for medical devices. An exemplary medical device may include a microcatheter. The microcatheter may include an elongated shaft having a distal end and a proximal end. The elongated shaft may include an outer layer that may be formed from a polymer and an intermediate layer that may be formed from a braid having multiple strands, each strand containing four filaments, each filament being a circular or other shape elongate metal piece having an outer diameter of less than 0.0009 inches (0.023 mm). The braid may have a surface area coverage of at least 70% on the inner polymer layer. The elongated shaft may include an inner layer that may be formed from a polymer and a distal polymer tip that may be attached to the distal end of the elongated shaft. Some examples may have a strand consisting of exactly four filaments, each being a circular metal.

[0005] In place of, or in addition to, any of the embodiments described above, the braid may be formed in a two-over, two-under configuration.

[0006] In place of, or in addition to, any of the embodiments described above, at least one strand may include at least one stainless steel filament and at least one tungsten filament.

[0007] In place of, or in addition to, any of the embodiments described above, the filament may have an outer diameter of 0.00075 inches (0.019 mm). In place of or in addition to any of the above embodiments, the long shaft may have an outer diameter of less than 3 French and an inner diameter in the range of about 0.025 inches to about 0.027 inches (about 0.64 mm to about 0.69 mm).

[0008] In place of, or in addition to, any of the embodiments described above, the elongated shaft may provide a torque response of at least 0.9:1. In place of, or in addition to, any of the above embodiments, the elongated shaft may provide a torque response of at least 0.95:1.

[0009] In place of or in addition to any of the embodiments described above, the braid may have a number of picks per inch (PPI) in the range of about 100 to about 140.

[0010] In place of or in addition to any of the embodiments described above, the braid may have a range of about 120 PPI. In place of or in addition to any of the embodiments described above, the braid may comprise 12 to 20 strands, each having four metal filaments, the four metal filaments having an outer diameter of approximately 0.0006 to 0.0009 inches (approximately 0.015 mm to approximately 0.023 mm).

[0011] In place of or in addition to any of the above embodiments, the braid may have 16 strands. In place of, or in addition to, any of the embodiments described above, the filament may have an outer diameter of approximately 0.00075 inches (approximately 0.019 mm).

[0012] In addition to or instead of any of the embodiments described above, the tip portion may be formed from a polymer having a Shore hardness of less than 40D. In place of, or in addition to, any of the above embodiments, the long shaft may have a burst pressure in the range of 1000 to 3000 psi.

[0013] In place of, or in addition to, any of the above embodiments, the long shaft may have a burst pressure exceeding 1200 psi. In another embodiment, the microcatheter may include an elongated shaft having a distal end and a proximal end. The elongated shaft may include an outer layer which may be formed from a polymer and an intermediate layer which may be formed from a braid having multiple strands, each strand having four filaments, each filament being a circular metal having an outer diameter of 0.00075 inches (approximately 0.019 mm), and the braid may include an intermediate layer which has a surface area coverage of at least 70% and an inner layer which may be formed from a polymer. The braid may be formed in a 2-over-2-under configuration. The distal polymer tip is attached to the distal end of the elongated shaft, and the elongated shaft may provide a torque response of at least 0.9:1.

[0014] In place of, or in addition to, any of the embodiments described above, at least one strand may include at least one stainless steel filament and at least one tungsten filament.

[0015] In place of or in addition to any of the embodiments described above, the braid may have a number of picks per inch (PPI) in the range of about 100 to about 140.

[0016] In place of or in addition to any of the embodiments described above, the braid may have a range of about 120 PPI. In place of or in addition to any of the embodiments described above, the braid may comprise 12 to 20 strands, each having four metal filaments, and each metal filament may have an outer diameter of approximately 0.0006 to 0.0009 inches (approximately 0.015 mm to approximately 0.023 mm).

[0017] The above summary of some embodiments is not intended to describe each disclosed embodiment or all implementations of this disclosure. The drawings and the following detailed description illustrate these embodiments more specifically. [Brief explanation of the drawing]

[0018] This disclosure can be more fully understood by considering the following detailed description in conjunction with the accompanying drawings. [Figure 1] Figure 1 is a plan view of a microcatheter according to an embodiment of the present invention. [Figure 2] Figure 2 is a partial view of the elongated shaft of a microcatheter showing the outer layer, intermediate layer, and inner layer according to an embodiment of the present invention. [Figure 3] Figure 3 is a longitudinal partial cross-sectional view of a portion of the elongated shaft as shown in Figure 2. [Figure 4] Figure 4 is a partial view of the braiding of the elongated shaft of a microcatheter according to an embodiment of the present invention. [Figure 5] Figure 5 is an exemplary graph comparing the burst pressures of a microcatheter made using three wire strands and a microcatheter made using four wire strands. [Figure 6] Figure 6 is an exemplary graph comparing the kink radii of a microcatheter made using three wire strands and a microcatheter made using four wire strands. [Figure 7] Figure 7 is an exemplary graph comparing the three-point bending loads of a microcatheter made using three wire strands and a microcatheter made using four wire strands. [Figure 8] Figure 8 is an exemplary graph comparing the axial loads of a microcatheter made using three wire strands and a microcatheter made using four wire strands. [Figure 9] Figure 9 is an exemplary graph showing the torque response of a microcatheter according to an embodiment of the present invention.

Mode for Carrying Out the Invention

[0019] This disclosure can conform to various modifications and alternative forms, the details of which are shown in the drawings as examples and are described in detail. However, it should be understood that the intention is not to limit the present invention to the specific embodiments described. On the contrary, it is intended to cover all modifications, equivalents, and alternatives within the spirit of this disclosure.

[0020] For the terms defined below, these definitions shall apply unless different definitions are provided in the claims or elsewhere in this specification. In this specification, all numerical values are considered to be modified by the term "about", whether explicitly stated or not. The term "about" generally refers to a range of numerical values that a person skilled in the art would consider to be equivalent to the recited value (e.g., having the same function or result). In many cases, the term "about" may include the value rounded to the nearest significant digit. The recitation of numerical ranges by endpoints includes all numbers within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5). As used in this specification and the appended claims, the singular forms "a", "an", and "the" include plural referents unless the context clearly indicates otherwise. As used in this specification and the appended claims, the term "or" is generally used in the sense of "and / or" unless the context clearly indicates otherwise. Note that references in this specification to "certain embodiments", "some embodiments", "other embodiments", etc. indicate that the described embodiments may include one or more specific features, structures, and / or characteristics. However, such descriptions do not mean that all embodiments necessarily include the specific features, structures, and / or characteristics. Furthermore, when a specific feature, structure, and / or characteristic is described in relation to an embodiment, it should be understood that such feature, structure, and / or characteristic can also be used in relation to other embodiments, unless explicitly stated to the contrary or unless it is clearly stated otherwise.

[0021] The following detailed description should be read with reference to the drawings, where similar elements in different drawings are numbered the same. The drawings are not necessarily to a specific scale and illustrate exemplary embodiments; they are not intended to limit the scope of the invention.

[0022] Microcatheters are used for various therapeutic procedures such as the diagnosis of vascular complications, delivery of embolic treatments, and intravascular mapping. Figure 1 shows an example of such a microcatheter 10. As shown in Figure 1, the microcatheter 10 may include a long shaft 12 having a distal end 16 and a proximal end 14. The microcatheter 10 may have a length in the range of about 50 to 200 centimeters and may have an outer diameter (OD) of less than 3 French. In some cases, the microcatheter 10 may have an OD of 1.7 French, 2 French, 2.5 French, 2.8 French, or any other suitable outer diameter. In some cases, the microcatheter 10 may have an OD of about 2.6 French at the distal end 16 and an OD of about 2.8 French at the proximal end 14. In some cases, the microcatheter 10 may have an inner diameter (ID) of about 0.025 inches (about 0.64 mm) to about 0.027 inches (about 0.69 mm). In other cases, the microcatheter 10 may have an ID of approximately 0.02 inches (approximately 0.51 mm), 0.03 inches (0.76 mm), or any other suitable inner diameter. These sizes may vary depending on the specific application.

[0023] In some cases, the distal tip 19 may be connected to or positioned around the distal end 16 of the elongated shaft 12. The distal tip 19 may be a polymeric distal tip 19, which can be formed from an elastomer (e.g., Pebax®), a thermoplastic polymer, or any other suitable polymer. The distal tip may be formed from a material softer than the rest of the outer shaft of the microcatheter, for example, by using a polymer or elastomer having a Shore hardness of less than 40D (softer material). In some cases, the distal tip 19 may be formed from a polymer having a Shore hardness of about 35D. In some cases, the distal tip 19 may have a length of about 1 millimeter (mm). In other cases, the distal tip 19 may have a length of about 1.5 mm, 1.3 mm, 1.7 mm, or any other suitable length. The distal tip 19 may include an outer diameter sized to match the OD of the microcatheter 10. In some cases, the distal tip 19 may include ODs of 1.7 French, 2 French, 2.5 French, 2.8 French, or any other suitable diameter. Some examples may include a transition region with varying hardnesses, such as using Pebax of varying hardnesses (e.g., 75D, 63D, 55D, 45D, and up to the tip at 35D from proximal to distal). These are merely examples.

[0024] In some cases, as shown in the illustration, the hub and strain relief assembly 18 may be connected to or positioned around the proximal end 14 of the elongated shaft 12. The hub and strain relief assembly 18 may include a body portion 20, a pair of flanges 22 configured to improve gripping, and a strain relief portion 24 intended to reduce kinking. The hub and strain relief assembly 18 is a conventional design and can be mounted by the prior art.

[0025] As described, the elongated shaft 12 is configured to provide an enhanced torque response, meaning that a particular rotation occurring at the proximal end 14 is transmitted to the distal end 16. In some cases, the elongated shaft 12 may be configured to provide a sufficient torque response such that a particular rotation occurring at the proximal end 14 provides a torque response of at least 0.9:1 (e.g., 90 percent). As an example, a 90-degree rotation occurring at the proximal end 14 correlates to an 81-degree rotation occurring at the distal end 16. In some cases, the elongated shaft 12 can provide a torque response of at least 0.95:1 (e.g., 95 percent). As an example, a 90-degree rotation occurring at the proximal end 14 correlates to a rotation of approximately 85.5 degrees occurring at the distal end 16. In other cases, the elongated shaft 12 may provide a torque response of at least 0.98:1 (e.g., 98 percent) at the distal end 16. For example, a 360° rotation occurring at the proximal end 14 correlates to a rotation of approximately 356° occurring at the distal end 16. These are merely examples.

[0026] In some cases, the microcatheter 10 may be designed as an over-the-wire (OTW) microcatheter configured to pass its entire length over a guidewire. If the microcatheter 10 is instead a rapid-exchange microcatheter, it should be understood that a side port may be provided to allow the guidewire to be withdrawn from the distal microcatheter lumen relative to the proximal hub and tension-relieving assembly 18, as shown in U.S. Patent No. 8,636,714 (the disclosure of which is incorporated herein by reference).

[0027] As described above, the elongated shaft 12 may be configured to provide sufficient torque response. Figure 2 is a partial view of the elongated shaft 30 of a microcatheter according to one embodiment of the present invention. Figure 3 is a longitudinal partial cross-sectional view of a portion of the elongated shaft 30 as shown in Figure 2. The elongated shaft 30 may be an example of the elongated shaft 12 shown in Figure 1. It will be understood that the illustrated portion of the elongated shaft 30 may correspond to essentially any portion of the elongated shaft 12 shown in Figure 1. The elongated shaft 30 may include an outer layer 32, an intermediate layer 34, an inner layer 36, and a lumen 38 extending through them. The lumen 38 may be considered a guidewire lumen, as well as an injection lumen, etc. As an example, during use, the operator may insert a microcatheter (e.g., microcatheter 10) over a guidewire (not shown). Once the target vessel is reached, the guidewire is removed and fluid may be injected into the target site through the lumen 38.

[0028] The inner layer 36 of the elongated shaft 30 may be formed from or include a coating of a material having a sufficiently low coefficient of friction. Examples of suitable materials include polytetrafluoroethylene (PTFE). The inner layer 36 may be dimensioned to define a lumen 38 having an appropriate inner diameter to accommodate intended uses such as high flow rates. In some cases, the inner layer 36 may define a lumen 38 having a diameter of approximately 0.025 inches (approximately 0.64 mm) to 0.027 inches (0.69 mm), or larger or smaller.

[0029] The outer layer 32 may be formed from a polymer capable of providing desired flexibility and strength. In some cases, the outer layer 32 may be formed from a nylon polymer, a thermoplastic polymer, an elastomer polyamide, or any other suitable polymer. The outer layer 32 may be dimensioned to define the outer diameter of the elongated shaft 30. In some cases, as described with reference to Figure 1, the outer diameter of the elongated shaft 30 may be less than 3 French. In some cases, the outer layer 32 may have an OD of 1.7 French, 2 French, 2.5 French, 2.8 French, or any other suitable outer diameter. The outer layer 32 may comprise multiple segments to provide properties (lubricity, flexibility, outer diameter, etc.) that vary along the length of the assembly. Furthermore, two or more outer layers 32 may be used at desired locations.

[0030] The intermediate layer 34 is positioned between the outer layer 32 and the inner layer 36 and may be formed from a braid. The intermediate layer 34 can be considered a reinforcing layer that increases the torque response of the long shaft 30. The intermediate layer 34 may be formed from any suitable material such as stainless steel, tungsten, gold, titanium, silver, copper, platinum, or nitinol. In some cases, the intermediate layer 34 may be formed from a non-metallic material such as polymer fibers, glass fibers, or liquid crystal polymer (LCP) fibers. The intermediate layer 34 may be formed using various different weave patterns such as three-over-three and four-over-four. In some cases, the intermediate layer 34 may be formed using a two-over, two-under configuration, as further explained with reference to Figure 4.

[0031] Figure 4 is a partial view of a braid 40 of a long shaft (e.g., long shaft 30). As described above with reference to Figures 2 and 3, the braid 40 may form an intermediate layer (e.g., intermediate layer 34) of the long shaft (e.g., long shaft 30). The braid 40 is formed from a plurality of strands 42, each strand may be formed from a plurality of filaments 44. The braid 40 may contain 12 to 20 strands 42. In some cases, the braid 40 may contain 16 strands 42. The braid 40 may have a number of picks per inch (PPI) in the range of about 100 to about 140. In some cases, the braid 40 may have a range of about 120 PPI. In some embodiments, the braid 40 has a coverage of at least 70 percent of the surface area of ​​the inner layer 36, thereby providing a long shaft (e.g., long shaft 30) having high burst pressure performance as further described with reference to Figure 5. In some cases, the braid 40 may have a coverage of at least 60 percent, 80 percent, 90 percent, or any other suitable percentage of the surface area of ​​the inner layer 36.

[0032] In some cases, as shown in Figure 4, each of the multiple strands 42 may contain four filaments 44. The filaments 44 may be formed from any suitable material such as stainless steel, tungsten, gold, titanium, silver, copper, platinum, or nitinol. In some cases, at least one strand 42 may contain at least one stainless steel filament 44 and at least one tungsten filament 44. In other cases, at least one strand 42 may contain two stainless steel filaments 44 and two tungsten filaments 44. In other cases, at least one strand 42 may be formed from four stainless steel filaments 44, and a second strand 42 may be formed from four tungsten filaments 44. Each strand 42 may, if desired, be formed from any suitable combination of multiple filaments 44. Some exemplary strands may have five or more filaments. Other examples may have a strand consisting of exactly four filaments.

[0033] In some cases, each strand 42 is formed from four filaments 44 that are stacked together and braided in a 2-over-2-under configuration. The tests shown below demonstrate that the braiding of four filaments 44 in a 2-over-2-under configuration provides a longer shaft (e.g., a longer shaft 30) with a greater torque response, allowing for greater pushability and thereby reducing the number of kinks that may form in the longer shaft.

[0034] In some examples, the filaments may have a circular cross-sectional shape. Alternatively, the filaments may include rectangular, elliptical, or any other suitable cross-sectional shape. Each filament 44 may have an outer diameter of less than 0.0009 inches (0.023 mm). In some cases, each filament 44 may have an outer diameter of 0.00085 inches (0.022 mm), 0.0008 inches (0.020 mm), 0.00075 inches (0.019 mm), 0.0006 inches (0.015 mm), or any other suitable outer diameter. Multiple filaments may have outer diameters ranging, for example, from about 0.0006 inches (approximately 0.015 mm) to about 0.0009 inches (approximately 0.023 mm), or from about 0.00075 inches (approximately 0.019 mm) to about 0.00085 inches (approximately 0.022 mm). Each filament may be the same size and shape, or multiple filaments may be of different sizes and shapes. For example, a strand 42 may include two larger tungsten filaments 44 and two smaller stainless steel filaments 44.

[0035] Figure 5 is an exemplary graph 100 showing the difference in burst pressure 120 between a microcatheter shaft with a reinforcement layer consisting of three wire strands and a microcatheter shaft with a reinforcement layer consisting of four wire strands, each in a 2-over-2-under configuration. As shown in Figure 5, the burst pressure 120 measured in pounds per square inch (PSI) for a microcatheter containing a braid formed from three filaments was compared with that of a microcatheter containing a braid formed from four filaments, each in a 2-over-2-under configuration. The maximum burst pressure 110 may be the maximum pressure that can be applied to the microcatheter before the microcatheter wall breaks (e.g., rupture or leakage). As shown, the average maximum burst pressure 110 for a microcatheter containing a braid formed from three filaments was 919.6 PSI (6340.4 kPa), as referenced in 130. The average maximum burst pressure of a microcatheter containing a braid formed from four filaments was 1351.8 PSI (9320.3 kPa), as referenced in 140. As described, the braid formed from four filaments has a coverage of at least 70 percent of the inner layer surface area, thereby increasing the burst pressure of the microcatheter. In some cases, the braid may have a coverage of at least 60 percent, 80 percent, 90 percent, or any other preferred percentage of the inner layer surface area. Therefore, it is more desirable to use a microcatheter containing a braid formed from four filaments (e.g., braid 40) because a higher burst pressure can enable a higher flow rate.

[0036] Figure 6 is an exemplary graph comparing the kink radius of a microcatheter fabricated using three wire strands (e.g., microcatheter 10) and a microcatheter fabricated using four wire strands (e.g., microcatheter 10). The kink radius is the minimum radius at which the lumen of the microcatheter collapses, thereby forming a kink. As shown in Figure 6, the kink radius 220 measured in millimeters (mm) for a microcatheter containing a braid formed from three filaments was compared with that of a microcatheter containing a braid formed from four filaments, each in a 2-over-2-under configuration. Furthermore, Figure 6 shows a comparison of the kink radius 220 between microcatheters formed from three-wire braids and four-wire braids made from Pebax® 72D and microcatheters formed from three-wire braids and four-wire braids made from Vestamid® ML21. As shown in the figure, the minimum kink radius 210 for a microcatheter formed from Pebax® 72D including a braid formed from three filaments is 3.36266 mm, as referenced by 230. The minimum kink radius 210 for a microcatheter formed from Pebax® 72D including a braid formed from four filaments is 3.0119 mm, as referenced by 240. The minimum kink radius 210 for a microcatheter formed from Vestamid® ML21 including a braid formed from three filaments is 3.16368 mm, as referenced by 250. The minimum kink radius 210 for a microcatheter formed from Vestamid® ML21 including a braid formed from four filaments is 2.93758 mm, as referenced by 260.As described, a braid formed from four filaments has a coverage of at least 70 percent of the inner layer surface area, thereby minimizing the kink radius of the microcatheter. Therefore, it is more desirable to use a microcatheter that includes a braid formed from four filaments (e.g., braid 40).

[0037] Figure 7 is an exemplary graph 300 comparing the three-point bend load of a microcatheter fabricated using three wire strands (e.g., microcatheter 10) with the three-point bend load of a microcatheter fabricated using four wire strands (e.g., microcatheter 10). The maximum three-point bend load 320 measures the bending stiffness, such as the flexibility of the long shaft (e.g., long shaft 12) of the microcatheter (e.g., microcatheter 10). In some examples, the proximal portion of the microcatheter (e.g., proximal end 14) may have bending stiffness that allows for the flexibility required when guiding winding blood vessels. Furthermore, in some examples, the distal portion of the microcatheter (e.g., distal end 16) should be relatively more flexible to allow for better trackability, such as over a guidewire. Similar to other graphs, the shafts or assemblies of the tested microcatheters were formed using multiple braids with multifilament strands (having three or four filaments) in a two-over, two-under braid between the inner and outer layers.

[0038] As shown in Figure 7, the bending loads (e.g., maximum three-point bending load 320, maximum bending load 310) measured in Newtons (N) for microcatheters containing braids formed from three filaments were compared with those for microcatheters containing braids formed from four filaments. Furthermore, Figure 7 shows a comparison of the bending loads 320 for microcatheters formed from three-wire and four-wire braids made from Pebax® 35D, microcatheters formed from three-wire and four-wire braids made from Pebax® 72D, and microcatheters formed from three-wire and four-wire braids made from Vestamid® ML21. As shown, the maximum bending load 310 for a microcatheter formed from Pebax® 35D containing a braid formed from three filaments includes a maximum bending load of 0.027650 N, as referenced by 330. The maximum bending load 310 of a microcatheter formed from Pebax® 35D, which includes a braid formed from four filaments, is 0.029344 N, as referenced by 340. The maximum bending load 310 of a microcatheter formed from Pebax® 72D, which includes a braid formed from three filaments, is 0.236758 N, as referenced by 350. The maximum bending load 310 of a microcatheter formed from Pebax® 72D, which includes a braid formed from four filaments, is 0.257752 N, as referenced by 360. The maximum bending load 310 of a microcatheter formed from Vestamid® ML21, which includes a braid formed from three filaments, is 0.419714 N, as referenced by 370. The maximum bending load 310 of a microcatheter formed from Vestamid® ML21, which includes a braid formed from four filaments, is 0.450676 N, as referenced by 380.Therefore, it is more desirable to use a microcatheter that includes a braid formed from four filaments (e.g., braid 40).

[0039] Figure 8 is an exemplary graph 400 comparing the axial load of a microcatheter fabricated using three wire strands (e.g., microcatheter 10) with the axial load of a microcatheter fabricated using four wire strands (e.g., microcatheter 10). The axial load 420 measures the buckling strength, e.g., indentation strength, of the long shaft (e.g., long shaft 12) of the microcatheter (e.g., microcatheter 10). In some examples, the proximal portion of the microcatheter (e.g., proximal end 14) may have higher axial stiffness for better indentation strength. In some examples, the distal portion of the microcatheter (e.g., distal end 16) should be flexible to allow for better followability, such as over a guidewire.

[0040] As shown in Figure 8, the axial load 420, measured in Newtons (N), for a microcatheter containing a braid formed from three filaments was compared with that of a microcatheter containing a braid formed from four filaments. Furthermore, Figure 8 shows a comparison of the axial load 420 for microcatheters formed from three-wire and four-wire braids made from Pebax® 35D, microcatheters formed from three-wire and four-wire braids made from Pebax® 72D, and microcatheters formed from three-wire and four-wire braids made from Vestamid® ML21. As shown, the maximum axial load 410 of a microcatheter formed from Pebax® 35D containing a braid formed from three filaments is 0.207534 N, as referenced by 430. The maximum axial load 410 of a microcatheter formed from Pebax® 35D, which includes a braid formed from four filaments, is 0.281686 N, as referenced by 440. The maximum axial load 410 of a microcatheter formed from Pebax® 72D, which includes a braid formed from three filaments, is 3.01399 N, as referenced by 450. The maximum axial load 410 of a microcatheter formed from Pebax® 72D, which includes a braid formed from four filaments, is 4.09006 N, as referenced by 460. The maximum axial load 410 of a microcatheter formed from Vestamid® ML21, which includes a braid formed from three filaments, is 5.55412 N, as referenced by 470. The maximum axial load 410 of a microcatheter formed from Vestamid® ML21, which includes a braid formed from four filaments, is 5.75502 N, as referenced by 480.Therefore, it is more desirable to use a microcatheter that includes a braid formed from four filaments (e.g., braid 40).

[0041] Figure 9 is an exemplary graph 500 showing the torque response of a microcatheter (e.g., microcatheter 10) according to one embodiment of the present invention. The tested microcatheter includes a 2-over-2-under braid with 75% coverage, consisting of multiple strands, each having 4 filaments, and each filament is a circular metal wire with an outer diameter of 0.00075 inches (0.019 mm), with a distal outer diameter of 2.6 F and a proximal outer diameter of 2.8 F, using an inner PTFE layer and Vestamid® ML21, transitioning to Pebax 35D at the distal tip, and having a total length of 135 cm. As shown in Figure 9, line 530 shows a torque response of 1:1, meaning that the proximal rotation 520 correlates to 100 percent of the distal rotation. Line 540 shows the torque response of a microcatheter according to one embodiment of the present invention. As shown in the figure, the elongated shaft may be configured to provide sufficient torque response such that a specific rotation occurring at the proximal end (e.g., proximal rotation 520) provides a torque response of at least 0.9:1 (e.g., 90 percent). In some cases, the proximal rotation 520 may provide a torque response of 0.98:1 (e.g., 98 percent).

[0042] The microcatheter 10 and its various components can be manufactured by essentially any suitable manufacturing technique, including extrusion, co-extrusion, molding, casting, machining, etc., or by any other suitable technique. Furthermore, the various structures can include materials commonly associated with medical devices, such as metals, metal alloys, polymers, metal-polymer composites, ceramics, combinations thereof, or any other suitable material. These materials can be transparent or translucent to aid in visualization during treatment. Some examples of suitable metals and metal alloys include stainless steel, e.g., 304V, 304L, and 316LV stainless steel; mild steel; nickel-titanium alloys, e.g., linear elastic and / or superelastic Nitinol; other nickel alloys, e.g., nickel-chromium-molybdenum alloys (e.g., UNS:N06625, e.g., INCONEL® 625, UNS:N06022, e.g., HASTELLOY® C-22, UNS:N10276, e.g., HASTELLOY®) (Registered Trademark) C276, other HASTELLOY® alloys, etc.), nickel-copper alloys (e.g., UNS:N04400, e.g., MONEL® 400, NICKELVAC® 400, NICORROS® 400, etc.), nickel-cobalt-chromium-molybdenum alloys (e.g., UNS:R30035, e.g., MP35-N, etc.), nickel-molybdenum alloys (e.g., UNS:N10665, e.g., HASTELLOY® ALLOY Examples include B2, other nickel-chromium alloys, other nickel-molybdenum alloys, other nickel-cobalt alloys, other nickel-iron alloys, other nickel-copper alloys, other nickel-tungsten alloys or tungsten alloys, etc.; cobalt-chromium alloys; cobalt-chromium-molybdenum alloys (e.g., UNS:R30003, e.g., ELGILOY®, PHYNOX®, etc.); platinum-high stainless steels; combinations thereof; etc.; or other suitable materials.

[0043] Some examples of suitable polymers include polytetrafluoroethylene (PTFE), ethylenetetrafluoroethylene (ETFE), fluorinated ethylene propylene (FEP), polyoxymethylene (POM, e.g., DELRIN® available from DuPont), polyether block esters, polyurethane, polypropylene (PP), polyvinyl chloride (PVC), polyether esters (e.g., ARNITEL® available from DSM Engineering Plastics), ether or ester-based copolymers (e.g., butylene / poly(alkylene ether) phthalate and / or other polyester elastomers, e.g., HYTREL® available from DuPont), and polyamides (e.g., DURETHAN® or Elf available from Bayer). CRISTAMID® (available from Atochem), elastomer polyamides, block polyamides / ethers, polyether block amides (PEBA, available as trade name PEBAX®, for example), ethylene vinyl acetate copolymer (EVA), silicone, polyethylene (PE), Marlex® high-density polyethylene, Marlex® low-density polyethylene, linear low-density polyethylene (e.g., REXELL®), polyester, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polytrimethylene terephthalate, polyethylene naphthalate (PEN), polyether ether ketone (PEEK), polyimide (PI), polyetherimide (PEI), polyphenylene sulfide (PPS), polyphenylene oxide (PPO), poly-p-phenylene terephthalamide (e.g., KEVLAR®), polysulfone, nylon, nylon-12 (EMS American Examples include GRILAMID® (available from Grilon), perfluoro(propyl vinyl ether) (PFA), ethylene vinyl alcohol, polyolefins, polystyrene, epoxy, polyvinylidene chloride (PVdC), polycarbonate, ionomers, biocompatible polymers, other suitable materials, or mixtures, combinations, copolymers, polymer / metal composites thereof.

[0044] It should be understood that this disclosure is illustrative in many respects. Modifications can be made without exceeding the scope of this disclosure, particularly in terms of shape, size, and sequence of processes. This may include, to the appropriate extent, using any feature of one exemplary embodiment in other embodiments. Naturally, the scope of the invention is defined by the language expressed in the appended claims.

Claims

1. It is a microcatheter, A long shaft having a distal end and a proximal end, wherein the long shaft is An outer layer formed of polymer, An inner layer formed of polymer, the inner layer defining the guide wire lumen, An intermediate layer formed of a braid having multiple strands, each strand containing at least four metal filaments having an outer diameter of less than 0.023 mm (0.0009 inches), the braid having a surface area coverage of at least 70% of the outer surface of the inner layer, and at least one of the multiple strands containing four tungsten filaments, and an elongated shaft, including the intermediate layer, A microcatheter comprising a distal polymer tip attached to the distal end of the long shaft.

2. The microcatheter according to claim 1, wherein the braid is formed in a 2-over 2-under configuration.

3. The microcatheter according to claim 1 or 2, wherein at least one strand comprises at least one stainless steel filament and at least one tungsten filament.

4. The microcatheter according to claim 1 or 2, wherein the filament has an outer diameter of 0.019 mm (0.00075 inches).

5. The aforementioned long shaft is Outer diameter less than 3 French, A microcatheter according to claim 1 or 2, having an inner diameter in the range of 0.64 mm (0.025 inches) to 0.69 mm (0.027 inches).

6. The long shaft provides a torque response of at least 0.9:1, as described in claim 1 or 2.

7. The microcatheter according to claim 6, wherein the elongated shaft provides a torque response of at least 0.95:

1.

8. The microcatheter according to claim 1 or 2, wherein the braid has a pick count (PPI) in the range of 100 to 140 per inch (25.4 mm).

9. The microcatheter according to claim 8, wherein the braid has a range of 120 PPI.

10. The microcatheter according to claim 1 or 2, wherein the braid comprises 12 to 20 strands, each strand having four metal filaments having an outer diameter of 0.015 to 0.023 mm (0.0006 to 0.0009 inches).

11. The microcatheter according to claim 10, wherein the braid has 16 strands.

12. The microcatheter according to claim 10, wherein the filament has an outer diameter of 0.019 mm (0.00075 inches).

13. Each strand comprises four circular metal filaments, according to claim 1 or 2, the microcatheter.

14. The microcatheter according to claim 1 or 2, wherein the long shaft has a burst pressure in the range of 1,000 to 3,000 psi.

15. The microcatheter according to claim 14, wherein the long shaft has a burst pressure greater than 1200 psi.

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