HK40112329A - Intravascular guidewire and microcatheter system - Google Patents

Description

Intravascular guidewire and microcatheter system

Cross-references to related applications

This application claims priority and benefit to U.S. Utility Application No. 17/901,819, filed September 1, 2022, entitled "Intravascular Guidewire and Microcatheter System"; U.S. Provisional Application No. 63/271,114, filed October 22, 2021, entitled "Intravascular Guidewire and Microcatheter System"; and U.S. Provisional Application No. 63/240,845, filed September 3, 2021, entitled "Microcatheter Device with Non-Linear Bending Stiffness," the entire contents of each of which are incorporated herein by reference.

Background Technology

Interventional devices (such as guidewires and catheters) are frequently used in the medical field to perform delicate procedures (minimally invasive surgery) deep within the human body. Typically, a catheter is inserted into a patient's femoral, radial, carotid, or jugular vein and guided by a guidewire through the patient's vascular system to reach the heart, brain, or other target anatomical structures. Once in place, the catheter can be used to deliver drugs, stents, embolic devices, radiopaque dyes, or other devices or substances to treat the patient in the desired manner.

In many applications, such interventional devices must be guided through the tortuous bends and kinks of the vascular system to reach the target anatomical structure. These devices (especially those closer to their distal ends) require sufficient flexibility to guide these winding pathways. However, other design aspects must also be considered. For example, the device must also provide sufficient torsion capability (i.e., the ability to transmit torque applied proximally all the way to the distal end), pushability (i.e., the ability to transmit axial thrust distally rather than bending and constraining the intermediate portion), and structural integrity to perform the intended medical function.

Ideally, catheter devices should have good axial response, such that when thrust is applied to the proximal end of the device on a guidewire (e.g., within the patient's vasculature), the central and distal portions of the device advance along the guidewire (e.g., further into the patient's vasculature) in response to the thrust. However, typically, as the catheter device advances within bends and kinks in the vasculature, much of the axial movement incidentally pushes the central portion of the device into the walls of the bends rather than actually advancing the distal end of the device. This lack of correspondence between the amount of axial thrust provided by the user proximally and the forward movement at the distal end makes guidance more difficult and less tactilely intuitive.

Therefore, there are several limitations in the field of guidewire and catheter systems, and there is a persistent need for systems that enable catheters to travel effectively on guidewires within vascular systems without requiring excessive thrust to reach the intended anatomical target.

Attached Figure Description

Various objects, features, characteristics, and advantages of the invention will become apparent and more readily understood from the following description of embodiments taken in conjunction with the accompanying drawings and appended claims, all of which form part of this specification. In the drawings, similar reference numerals may be used to denote corresponding or similar portions in the various figures, and the depicted elements are not necessarily drawn to scale, wherein:

Figure 1 shows an overview of the catheter system, including the catheter and hub.

Figure 2 shows a detailed view of the various cross-sections of the catheters in the catheter system;

Figures 3A to 3C show examples of single-beam, double-beam, and triple-beam segments, which can be included in the microfabrication axis used in the catheter system described herein;

Figure 4 shows a detailed view of the distal segment of the catheter;

Figures 5A to 5D are photographs showing the differences in axial response that can occur within a blood vessel (the artificial blood vessel shown), wherein Figures 5A and 5B show the axial response of a conventional catheter, and Figures 5C and 5D show the improved axial response of a catheter according to the present disclosure.

Figure 6 schematically shows a cross-section of the catheter during bending, illustrating how the catheter is configured to distribute bending, torsional, and axial forces within a tortuous anatomical structure.

Figures 7A and 7B show that the microfabrication axis is configured to compensate for the step change in stiffness in the outer polymer layer due to the transition from one polymer to another.

Figures 8A and 8B compare the bending stiffness distribution of the catheter device according to this disclosure (labeled "Plato 17") with the bending stiffness distribution of various conventional catheter devices, wherein Figure 8A shows the bending stiffness up to 60 cm from the distal tip and Figure 8B shows the bending stiffness up to 15 cm from the distal tip.

Figure 9 compares the outer diameter (labeled “Plato17”) of the catheter device according to this disclosure along the distal length with various conventional catheter devices;

Figure 10 illustrates an exemplary embodiment of a guidewire device that provides effective torsion and has a shapeable tip;

Figure 11 is a cross-sectional view of the guide wire device in Figure 10;

Figure 12 illustrates an exemplary embodiment of a tube structure that can be used with the guidewire devices of Figures 10 and 11, the tube having a bypass cutout pattern (i.e., a single beam cutout pattern) configured to provide effective flexibility and formability of the distal tip;

Figure 13 shows an alternative embodiment of the tube structure, which includes sections with an alternative single-beam cutout pattern;

Figure 14 shows an embodiment of a tubular structure including a double-beam cutout pattern of opposing beams with symmetrical spacing;

Figure 15 illustrates an embodiment of a tubular structure including a section with a single-sided single-beam cutout pattern;

Figure 16 illustrates an embodiment of a tubular structure that includes a bypass cutout pattern with an exemplary angular offset, providing a helical pattern for the final beam.

Figure 17 shows a perspective view of an embodiment of a tubular structure comprising three sections;

Figure 18A shows a side view of an embodiment of a tube, which includes a distal section of a core disposed therein;

Figure 18B shows a cross-sectional view of the tube in Figure 18A;

Figure 19 shows an enlarged side view of the transition between the first and second sections of the tubes in Figures 18A and 18B; and

Figure 20 shows an enlarged side view of the distal tip of the tubes of Figures 18A and 18B, including the second and third sections of the tube.

Detailed Implementation

Overview of Combined Systems

As mentioned above, many catheter devices lack a correspondence between proximal thrust and advancement of the distal and intermediate portions (e.g., when the catheter device is positioned above the guidewire within a tortuous section of the patient's vascular system). Conventional catheter devices typically utilize a variety of different materials to provide a gradient of bending stiffness from proximal to distal. However, whenever there is a transition between materials of different stiffnesses, the device's bending stiffness distribution, axial stiffness distribution, and torsional stiffness distribution involve abrupt step changes. Such abrupt changes in bending stiffness are undesirable because they concentrate mechanical stress at specific locations, causing kinks, disrupting the smooth movement and bending of the device, and complicating guidance in tortuous vascular systems. This abrupt change in bending stiffness leads to the aforementioned lack of correspondence between proximal thrust and distal advancement.

When faced with situations where applying excessive proximal thrust (e.g., greater than approximately 30 to 50 grams) fails to adequately advance the catheter device over the guidewire within the patient's vascular system, healthcare practitioners typically withdraw the catheter (and sometimes the guidewire) to re-attempt the routing of the guidewire and/or catheter through the patient's vascular system to reach the target. This situation results in time- and material-related inefficiencies and can adversely affect patient outcomes.

Therefore, at least one aspect of this disclosure is to provide guidewire and catheter systems capable of facilitating a desired axial response (e.g., maneuverability) for advancement through a patient's vascular system (or through an environment simulating a patient's vascular system). At least some of the example guidewire and catheter systems discussed herein exhibit a smooth distribution of bending stiffness along the length of the device, thereby helping to reduce the concentration of mechanical stress at specific locations. These features can enable the catheter devices of this disclosure to exhibit maneuverability, torsion, and/or bending flexibility, thereby allowing the catheter device to advance on the guidewire in a manner that reduces axial force loss to the vascular system walls and helps to travel efficiently (with minimal thrust) to the predetermined target.

The catheter device constructed according to this disclosure can advance on a guidewire within a tortuous path of a patient's vascular system in response to a thrust of 50g or less. For example, for an example tortuous path model with a total path length of 21.5cm, an inner diameter of 3.68mm, and three complete loops (each loop having a radius of 6.4mm), the guidewire and catheter system constructed according to this disclosure can advance on the guidewire with a thrust not exceeding 30g (and in some cases, not exceeding 20g). In particular, a catheter/guidewire system with a 0.017-inch (inner diameter) catheter and a 0.014-inch (outer diameter) guidewire travels through the model with a thrust not exceeding 18g, and a catheter/guidewire system with a 0.027-inch (inner diameter) catheter and a 0.024-inch (outer diameter) guidewire travels through the model with a thrust not exceeding 29g.

Other combinations of devices, such as the STRIKER SYNCHRO2 used in conjunction with the STRIKER EXCELSIOR SL-10, failed to achieve such performance. In fact, the STRIKER SYNCHRO 2 and STRIKER EXCELSIOR SL-10 combined system could not pass through the entire model even when a thrust of 50g was applied (which jumps to as high as 200g).

The ratio of the model to the tested catheter is 557% (e.g., the model's inner diameter is 3.68 mm, and the catheter's outer diameter is 0.66 mm). Combinations of guidewires and catheters of different sizes utilizing the structural features disclosed herein are also expected to perform similarly in models with similar size ratios. For example, similar effective results can be expected as long as the ratio of the model's inner diameter to the catheter's outer diameter is about 250% to about 800%, or about 300% or 350% to about 750%, or about 400% to about 700%, or about 450% to about 650%, or about 500% to about 600%, or such ratio falls within the range defined by any two of the foregoing values.

Therefore, the guidewire and catheter system of this disclosure enables medical practitioners to advance the catheter to the intended target more effectively, reducing situations where the safety level of thrust fails to advance the catheter fully on the guidewire, thereby avoiding the inefficiencies associated with withdrawal and/or re-advancement of the catheter device and/or guidewire device.

Tests similar to those shown in Figures 5A to 5D have demonstrated that catheters constructed according to this disclosure (e.g., including one or more features described with reference to catheter 102) are capable of advancing over a guidewire in a blood vessel in response to a thrust of about 50 g or less, or about 40 g or less, or about 35 g or less, or about 30 g or less, or about 25 g or less, or about 20 g or less (e.g., in the range of about 10 g to about 20 g, or about 20 g to about 30 g, or about 30 g to about 40 g, or about 40 g to about 50 g, or in the range of any of the foregoing values as the endpoints).

This functionality can be demonstrated by the catheter device of this disclosure in an operating environment (e.g., a real blood vessel or a model blood vessel) with a path length of about 21.5 cm having bends and/or loops (e.g., one bend and/or loop, two bends and/or loops, three bends and/or loops, or more than three bends and/or loops) having various radii (e.g., from about 3 mm to about 10 mm, such as 6.4 mm).

The disclosed system can be used for various vessel-to-catheter ratios. For example, the vessel inner diameter can range from about 2 mm to about 6 mm (e.g., about 3.68 mm), and the catheter outer diameter can range from about 0.2 mm to about 1.5 mm (e.g., about 0.66 mm), resulting in a vessel-to-catheter ratio ranging from about 133% to about 3,000% (e.g., about 371% or greater, such as 557% for a 3.68 mm lumen inner diameter and a 0.66 mm catheter outer diameter). Other sizes of test models can be used. Those skilled in the art will recognize that various catheter/guidewire combinations can be effectively tested against each other using this test model, provided that the same model conditions are used for each catheter/guidewire combination. This thrust test is easily performed within the capabilities of a skilled technician.

Example catheter device

Figure 1 is an overview of an example conduit device 100, which includes features described in more detail below, providing one or more of the following: improved axial responsiveness, improved bending force distribution, and/or smooth device bending stiffness distribution.

The conduit assembly 100 includes a conduit 102 that connects to a hub 104 at its proximal end and extends from the hub 104 to a distal end 103. The conduit 102 may be attached to the hub 104 using adhesives, friction fits, insertion molding, and/or other suitable attachment methods. A strain-relief member 106 is also provided on a proximal section of the conduit 102 near the hub 104. The strain-relief member 106 has an outer diameter substantially matching that of the adjacent section of the hub 104. The strain-relief member 106 extends from the hub 104 for a distance, tapering distally until the end of the conduit 102 emerges and extends further distally, having a substantially constant outer diameter. The strain-relief member 106 may include a groove pattern 108 provided in the section with the substantially constant outer diameter, which provides additional flexibility to the strain-relief member 106 and/or provides surface features for enhancing user grip and tactile engagement.

The working length of catheter 102 (i.e., the distance between the distal end of strain relief (106) and the distal end (103) of catheter (102) can vary depending on the specific application requirements. As an example, catheter 102 can have a working length of approximately 50 cm to approximately 200 cm, although shorter or longer lengths may be used where appropriate. The catheter size (typically referring to the inner diameter/lumen size) can also vary depending on the specific application requirements. Examples include 0.010 inches, 0.013 inches, 0.017 inches, 0.021 inches, 0.027 inches, 0.030 inches, 0.035 inches, 0.038 inches, 0.045 inches, 0.065 inches, 0.085 inches, 0.100 inches, or a range including any two of the above values as endpoints. The inner diameter of the catheter can taper gradually from a smaller distal portion to a larger proximal portion. In some applications, smaller or larger sizes may be used appropriately.

Furthermore, the outer diameter of the conduit 102 can vary depending on the specific application requirements. Examples include 0.010 inches, 0.013 inches, 0.017 inches, 0.021 inches, 0.026 inches, 0.027 inches, 0.030 inches, 0.035 inches, 0.038 inches, 0.045 inches, 0.065 inches, 0.085 inches, 0.100 inches, 0.135 inches, 0.165 inches, 0.20 inches, or a range including any two of the above values as endpoints.

Although the distal segment of catheter 102 is shown as having a straight shape in this example, other embodiments may include a shaped distal tip. For example, the distal segment of catheter 102 may have an angled shape, a zigzag shape (e.g., 45-degree angle, 90-degree angle, J-shape, etc.), a compound zigzag shape, or other suitable angled or curved shapes known in the art.

The catheter device 100 described herein can be used for a variety of interventional applications, most commonly for cardiovascular, peripheral vascular, and neurovascular interventional procedures. Examples include access to distal anatomy, traversing vascular lesions or blood clots, ischemia treatment, delivery of therapeutic agents (e.g., embolization coils or other embolic agents), injection of diagnostic agents (e.g., contrast agents or saline), retrieval applications, aspiration applications, or other applications where the use of a microcatheter is beneficial.

The internal features of catheter 102 will be described in more detail below. The outer surface of catheter 102 may be coated with a suitable coating material, such as a hydrophilic coating, to make the surface smoother. The coating material may substantially cover the entire working length of catheter 102 or a portion thereof. For example, the coating material may be applied to the distal 30% to 80% of the working length of catheter 102.

Figure 2 shows a detailed view of catheter 102, better illustrating some of its internal components and different longitudinal sections. As shown, catheter 102 includes an inner liner 110 defining the internal lumen of the device. Liner 110 may be formed of polytetrafluoroethylene (PTFE) and/or other suitable polymers. Coil 114 is located on a line near distal end 103. Coil 114 is attached to or positioned close to micromanufacturing shaft 112 (also referred to herein as the “inner shaft”) which extends proximally from the coil. An outer member 115, formed of one or more polymer materials, is typically heat-shrink laminated onto and through coil 114 and shaft 112, encasing both and also attached to the liner.

In one embodiment, coil 114 is formed of stainless steel and shaft 112 is formed of nitinol. These materials, when used in conjunction with other features described herein, have been found to provide effective axial response, efficient distribution of bending forces, and a smooth distribution of bending stiffness. Other embodiments may use one or more different materials for coil 114, shaft 112, or both. For example, in some embodiments, shaft 112 may comprise other hyperelastic alloys and/or one or more polymers, such as polyetheretherketone (PEEK) or other polyaryletherketones (PAEK). In some embodiments, coil 114 may comprise a hyperelastic alloy (such as nitinol), one or more other metals, alloys, or polymers.

The catheter 102 is configured such that the overall bending stiffness distribution transitions from higher stiffness (and less bending flexibility) in the proximal segment to lower stiffness (and greater bending flexibility) in the distal segment. In most applications, it is desirable to impart relatively high axial, torsional, and bending stiffness to the proximal segment of the device so that they can provide a good combination of flexibility, maneuverability, and torsion. However, the distal segment is typically guided through a tortuous vascular system and is therefore preferably relatively more flexible when bending. This stiffness distribution gradient can be achieved by adjusting certain features of the microfabricated shaft 112 and/or by coating the shaft with different polymer materials and embedding the shaft 112 into the external member 115. As explained in more detail below, in some embodiments, the microcatheter 112 and the external member 115 are configured to work together to provide an overall stiffness distribution that minimizes abrupt changes in stiffness and provides a smooth stiffness transition.

The illustrated embodiment includes a distal segment 120, an intermediate segment 122, and a proximal segment 124. In the distal segment 120, the outer member 115 is formed of a first polymer material 116a. In the intermediate segment 122, the outer member 115 is formed of a second polymer material 116b. In the proximal segment 124, the outer member 115 is formed of a third polymer material 116c. The polymer materials 116a, 116b, and 116c have different hardnesses, thus affecting the stiffness of their respective segments differently. The second polymer material 116b has a higher hardness than the first polymer material 116a, and the third polymer material 116c has a higher hardness than the second polymer material 116b.

As an example of a group of polymer materials found to be effective when used together, the first polymer material 116a may have a Shore D hardness of about 20 to about 30, the second polymer material 116b may have a Shore D hardness of about 30 to about 50, and the third polymer material 116c may have a Shore D hardness of about 50 to about 80. Other embodiments may vary these values as needed, such as making the distal portion softer, but the values described above have been found to be particularly effective. Polymer materials 116a, 116b, and 116c may be independently formed from suitable polymers, such as polyether block amide (PEBA) polymers, and the range in polymer hardness measurements can be from about 10 Shore A hardness to about 100 Shore D hardness.

Shaft 112 also includes features providing variable bending stiffness. As shown, shaft 112 is a tubular structure comprising a series of micro-machined cuts. The cuts form axially extending “beams” that connect successive circumferentially extending “rings.” The bending stiffness of shaft 112 can be adjusted by changing the pattern of these cuts. For example, the bending stiffness can be adjusted by changing the number of beams located between each pair of adjacent rings. “Double-beam sections” (such as those shown in distal section 120) comprise two beams between each pair of adjacent rings. “Three-beam sections” (such as those shown in intermediate section 122 and proximal section 124) comprise three beams between each pair of adjacent rings. All other things being equal (shaft material, cut depth, cut width, cut spacing), three-beam sections have greater bending stiffness than double-beam sections. “Single-beam sections” connecting adjacent rings with a single beam can also be used, which, all other things being equal, have even lower bending stiffness than double-beam sections. "Four-beam sections" and/or sections with more than four beams can also be used, and as the number of beams between each pair of adjacent rings increases, greater bending stiffness will be provided accordingly.

Figures 3A through 3C illustrate examples of single-beam, double-beam, and triple-beam segments, showing example arrangements of beams 130 and rings 132 within these segments. Depending on the angular offset (or absence of angular offset) between successive beam groups and/or the frequency of applied angular offsets (e.g., after each ring or after two or more rings), the beams can be configured in various arrangements. For example, the single-beam segment of Figure 3A includes a 180-degree angular offset from one beam to the next, the double-beam segment of Figure 3B includes a 90-degree offset from one pair of beams to the next pair, and the triple-beam segment of Figure 3C includes a 120-degree angular offset from one set of beams to the next set. While these types of offsets are advantageous, they are also associated with a preferred bending plane, and other arrangements can be provided to minimize or eliminate the preferred bending plane. Examples include helical arrangements, distributed arrangements, imperfect ramp arrangements, and sawtooth arrangements. Additional details regarding beam arrangements that may be used in the currently disclosed shaft 102 are provided in U.S. Patent No. 11,369,351 and U.S. Patent Application No. 2022/0105312, both of which are incorporated herein by reference in their entirety.

In addition to adjusting the number of beams positioned between the rings, the bending flexibility of shaft 112 can be controlled by adjusting the depth, width, and/or spacing of the slits. Typically, the slit width is set to a given value (e.g., corresponding to the cutting blade size), and the slit depth and/or slit spacing are more easily adjusted during manufacturing to provide desired control over the bending stiffness distribution. All else being equal, the final bending stiffness decreases when the ring width decreases (i.e., the slit spacing decreases), the slit width increases, and/or the beam width decreases (i.e., the slit depth increases). In the illustrated embodiment, the spacing between slits in the three-beam section (corresponding to the middle section 122 and the proximal section 124) gradually decreases as it gets closer to the distal section 120. Similarly, the double-beam section (corresponding to the distal section 120) starts with a larger spacing between slits, and the spacing between slits gradually decreases as it gets closer to coil 114 and distal end 103. Preferably, the transitions between different geometries (e.g., from three beams to two beams) are configured such that the bending stiffness is the same or similar at the transitions between these sections. Thus, shaft 112 provides a stiffness gradient by transitioning from a three-beam section to a two-beam section, and provides a stiffness gradient within the respective sections by transitioning from larger-spaced cuts to relatively smaller-spaced cuts.

At the distal end of the double-beam section, the cut pattern is configured to have relatively high flexibility in order to provide a smooth transition to the high flexibility of the coil 114. In some embodiments, the coil 114 is omitted and replaced by a further double-beam section (or alternatively, a single-beam section) extending to or near the distal end 103.

The lengths of segments 120, 122, and 124 can vary depending on specific application requirements or preferences. In one embodiment, the distal segment 120 may have a length of approximately 5 cm to approximately 40 cm, the intermediate segment 122 may have a length of approximately 10 cm to approximately 50 cm, and the proximal segment 124 occupies the remaining portion of the working length of the conduit 102. The illustrated embodiment shows the shaft 112 transitioning from a three-beam configuration to a two-beam configuration at the transition from the intermediate segment 122 to the distal segment 120. However, the transition of the shaft 112 does not necessarily correspond to a transition of polymer material defining separate segments 120, 122, and 124. As explained in more detail below, the shaft 112 and the outer member 115 are co-configured to compensate for and minimize abrupt changes in stiffness, and in some cases, this may involve a shaft transition zone that does not completely overlap with the polymer transition of the outer member 115.

Figure 4 shows a detailed view of the distal segment 120 of catheter 102, better illustrating certain distal features such as the liner 110, distal radiopaque marking strip 140, coil 114, shaft 112, and proximal radiopaque marking strip 142. Marking strips 140 and 142 are formed of a material that is less radiopaque than stainless steel. Examples include platinum, iridium, tungsten, other highly radiopaque metals and their alloys. The distal marking strip 140 provides an indication of the position of the distal end 103 of catheter 102, while the proximal marking strip 142 is offset by a predetermined length (e.g., 2 cm to 5 cm, or about 3 cm) to aid in the correct positioning of a separable embolic coil or other components deployed through catheter 102.

The shaft 112 may include a circumferential groove at the location where the proximal marking tape 142 is placed. This groove is capable of receiving the marking tape 142 such that the outer surface of the marking tape 142 does not extend excessively beyond the outer diameter of the shaft 112. Once covered by the external member 115, the outer diameter of the device on the proximal marking tape 142 remains substantially flush.

In the illustrated embodiment, coil 114 is variable pitch. Each end of coil 114 includes a pitch-narrowing region that provides a further improved transition in bending stiffness from one geometry to another, such as where the coil transitions to a microfabrication tube. For example, coil 114 may have a length of approximately 1 cm to approximately 3 cm. As shown, a portion of liner 110 may extend distally from coil 114 and distally marked coil 140 by a distance. For example, this distance may vary from approximately 0.2 mm to approximately 2 mm.

Catheter bending force distribution

The catheter devices described herein include features that effectively distribute bending forces, thereby providing improved axial response during use. Figures 5A and 5B illustrate common limitations in guiding a conventional catheter (the STRYKER EXCELSIOR SL-10 shown in this example) through an artificial vascular system. As the catheter approaches a bend in the vessel, a certain length of the catheter extends around the bend (the initial position in Figure 5A). Upon further push, before any sustained push causes the distal tip of the catheter to actually advance through the vascular system, the initial axial movement is used to push the catheter against the vessel wall to fill the bend (after the push position in Figure 5B; see the contact point indicated by the arrow). This reduced correspondence between the amount of axial push provided by the user proximally and the resulting forward movement distally makes guidance more difficult and less tactilely intuitive. Furthermore, as mentioned above, in many cases, practitioners cannot apply additional push to overcome the resistance generated by the vessel wall because doing so would risk injuring the patient.

In contrast to the response of conventional catheters in Figures 5A and 5B, Figures 5C and 5D illustrate the guidance of a bend in a vessel using the catheter 102 described herein. As shown, from the “initial” position (Figure 5C) to the advanced position (Figure 5D), less axial movement is used to fill the bend in the vessel, thus more axial movement is translated into actual movement of the distal end of the catheter 102. This capability stems from an improved ability to distribute bending forces along the length of the catheter 102. By better distributing bending forces, the catheter 102 better resists bending at any given location, thereby enabling better transmission of proximal axial movement to the distal end of the device.

Figure 6 further illustrates the ability of the conduit 102 to effectively distribute bending forces. Figure 6 shows a portion of the shaft 112 during bending. Polymer material 116 fills the gap between the beam and the ring of the shaft 112. For ease of observation, polymer material 116 is shown in discontinuous segments within each gap of the shaft 112. In most cases, polymer material 116 will fill the gap, fuse with the liner 110, and also extend on the outer surface of the shaft 112 to completely encapsulate and embed the shaft 112.

During bending of shaft 112, the shaft structure locally resists more bending stress and distributes that stress more effectively to adjacent portions of the structure compared to coils or braids that are less likely to distribute bending stress and are more likely to kink. Furthermore, polymer material 116 effectively acts as a series of dampers, each located between adjacent rings of shaft 112. Inside the bend, polymer material 116 is compressed, thus providing an outward pushing force against the rings and preventing further bending. Similarly, outside the bend, polymer material 116 is under tension, thus providing an inward pulling force against the rings and preventing further bending. The bending stiffness of conduit 102 is non-linear, as conduit 102 becomes increasingly resistant to bending in a non-linear manner as the bending angle increases.

During bending, conventional conduits begin to bend at the apex, and their cross-sectional shape may tend towards an "elliptical" shape. Once ellipticization begins, bending resistance decreases, making the conduit increasingly prone to bending as bending forces continue to be applied. In contrast, in the disclosed conduit 102, the bending resistance provided by the microfabrication structure and the effect of the polymer material 116 on the axis 112 tends to distribute bending forces along the axial length of the conduit 102 and avoids ellipticization and concentration of bending forces at specific kink points. For example, the bending resistance tends to extend the bend to a larger radius of curvature rather than concentrating the bend at a specific point, thus avoiding kink locations. Therefore, the bending resistance provided by the conduit structure provides enhanced axial responsiveness (as shown in Figures 5C and 5D) and also enhances protection against mechanical fatigue caused by bending stress.

Smoothness of duct bending stiffness distribution

Figures 7A and 7B illustrate how microfabrication axes can be configured to compensate for abrupt changes in stiffness in an external component due to a transition from one polymer to another. Figure 7A shows a portion of conduit 102 where a first polymer material 116a meets a second polymer material 116b. As shown in Figure 7B, this is associated with a sudden step change in the bending stiffness of the polymer layers of the external component. Such abrupt changes in bending stiffness are undesirable because they concentrate mechanical stresses, cause kinks, disrupt the smooth movement and bending of the device, and complicate guidance in tortuous vascular systems.

To compensate for this abrupt change, the shaft is configured such that the change in bending stiffness complements and compensates for the sudden change in bending stiffness of the polymer outer component. As a result, the overall bending stiffness of the conduit remains relatively smooth during the transition from the first polymer 116a to the second polymer 116b. Similar configurations can be used at other polymer transition zones to minimize and smooth abrupt changes in bending stiffness. The shaft 112 can be configured to compensate for the abrupt change in several ways. In the example of Figure 7A, because the bending stiffness of the second polymer 116b is higher than that of the first polymer 116a, the cut/gap configuration of the shaft 112 remains unchanged, or narrows over a short distance across the transition before unfolding again, to generally increase the shaft bending stiffness as it moves further proximally. Other means of adjusting the bending stiffness of the shaft 112 as described herein (e.g., adjusting the number of beams and/or the cut depth) can be used additionally or alternatively to achieve a smoothing of the overall bending stiffness distribution.

Configuring shaft 112 to compensate for abrupt changes in the bending stiffness of the polymer outer member 115 advantageously avoids the complexities of other conventional methods for smoothing such a transition. Existing methods rely on complex splicing arrangements or polymer co-extrusion and blending techniques. These add an additional layer of complexity to the manufacturing process and may still only slightly address the abruptness of the transition. Other methods utilize polymer pipes of different diameters and diameter gradients to compensate for transitions between polymer types. However, these methods can result in non-uniform outer diameters or increase the need to manage this situation in some way by stacking more material.

The smooth features described herein enable the fabrication of microcatheters with an improved flexural stiffness distribution compared to conventional microcatheters. Figures 8A and 8B show test results comparing the flexural stiffness distribution of a catheter fabricated according to this disclosure (labeled “Plato17”) with the flexural stiffness distribution of several conventional microcatheters. In the figures, “SL10” refers to Excelsior SL-10 (sold by Stryker Neuralvascular), “XT17” refers to Excelsior XT-17 (sold by Stryker Neuralvascular), “Ech14” refers to Echelon 14 (sold by Medtronic), “Ech10” refers to Echelon 10 (sold by Medtronic), and “HW17” refers to Headway 17 (sold by MicroVentionTerumo). Figure 8A shows the flexural stiffness distribution from 50 cm to 60 cm distal to the device, and Figure 8B provides a closer view of the flexural stiffness distribution from 15 cm distal to the device. In the figure, Plato 17 data represents the average of 5 repetitions, SL10 data represents the average of 3 repetitions, XT17 represents the average of 2 repetitions, Ech14 represents the average of 2 repetitions, Ech10 represents the average of 3 repetitions, and HW17 represents the average of 2 repetitions. As shown in the figure, the conduit corresponding to this disclosure provides a smoother distribution with fewer abrupt changes in bending stiffness.

Table 1 presents the data from Figures 8A and 8B by listing different distal segment dimensions and providing the highest measured “slope” within that segment. The “slope” represents the variation of bending stiffness (N· ^m² ) over the distance (cm) between measurement data points. It is evident from the data points in Figures 8A and 8B that measurements were taken in increments of 0.5 cm to 2.5 cm, typically every 1 cm. The increments are smaller in areas with a clear polymer transition, and larger once the distance to the distal end reaches approximately 15 to 20 cm. Therefore, the slope provides an indication of the abruptness of the change in bending stiffness over a given segment of the conduit.

Table 1: Stiffness variation of various microcatheters across different distal segments.

As shown in the figure, Plato 17 exhibits the lowest measured slope across the distal 15cm, 35cm, and 50cm segments. Based on the data in Figures 8A and 8B, and as further disclosed in Table 1, in some embodiments, the catheter device described herein has a bending stiffness slope ((N· ^m² )/ ^cm ) of no more than about 6.0 × ^10⁻⁷ for the distal 15cm segment, no more than about 9.0 × ^10⁻⁷ for the distal 35cm segment, and/or no more than about 9.0 × ^10⁻⁷ for the ^distal 50cm segment. Although the Plato 17 device configured according to this disclosure achieves each of the aforementioned features, none of the other existing catheter devices tested have achieved these features.

In some embodiments, at least a portion of the distal 35 cm of the catheter device has a bending stiffness of 5 × 10⁻⁶ N· ^m² or greater. In some embodiments, in addition to the aforementioned minimum stiffness, the catheter device described herein has a bending stiffness slope ((N· ^m² )/cm) of no more than about 4.0 × ^10⁻⁶ for the distal 35 cm segment and/or a bending stiffness slope ((N· ^m² )/cm) of no more than about 4.5 × ^10⁻⁶ for the distal 50 cm segment. As shown in Figures 8A and 8B and Table 1, while the Plato 17 device meets these requirements, the Headway-17 catheter does not meet the minimum bending stiffness requirement, and the other tested catheters do not meet the slope requirement.

Figure 9 compares the outer diameter of the Plato 17 device according to this disclosure with various conventional catheter devices along the distal length. Larger data points represent points where the polymer transition is clearly visible. Data from Figure 9 is also shown in Table 2, which illustrates the maximum diameter variation within the distal 15cm and distal 35cm segments of each catheter device. As shown, the diameter variation of the Plato 17 across the distal 15cm and distal 35cm segments does not exceed 0.0017 inches.

Table 2: Diameter variation of various microcatheters across different distal segments.

In some embodiments, the catheter device described herein has (1) a bending stiffness of 5 × ^10⁻⁶ N· ^m² or greater in at least a portion of the distal 35 cm of the catheter device, (2) an outer diameter variation of no more than 0.002 inches across the distal 15 cm segment and/or the distal 35 cm segment, and (3) a bending stiffness slope of no more than about 1.3 × ^10⁻⁶ ((N· ^m² )/cm) for the distal 15 cm segment, no more than about 4.2 × ^10⁻⁶ ((N· ^m² )/cm) for the distal 35 cm segment, and/or no more than about 1.1 × ^10⁻⁵ ((N· ^m² )/cm) for the distal 50 cm segment. Although the Plato 17 device configured according to this disclosure implements each of the foregoing features, none of the other existing catheter devices tested have been able to implement the foregoing features. In other words, the Headway-17 conduit did not meet the minimum bending stiffness requirement, the Echelon-10 conduit met the diameter variation requirement, and the other tested conduits did not meet the slope requirement.

In some embodiments, the aforementioned beneficial bending stiffness distribution characteristics are particularly suitable for transition sections in which the first polymer of the outer component transitions to the second polymer of the outer component.

In some embodiments, shaft 112 maintains substantially the same wall thickness along its length. Other conduit devices based on coils and/or braids typically have adjusted wall thicknesses at transition points. Variations in wall thickness can introduce additional kink points or stress points and/or require additional manufacturing steps to manage.

In some embodiments, because the shaft 112 transitions to the coil 114 and/or the coil 114 transitions to the farthest section of the liner 110, there may be acceptable variations in bending stiffness associated with the distal tip region. These variations in stiffness are acceptable because they are very close to the distal end 103. Therefore, in some embodiments, the distal 3 cm to 5 cm may be outside the aforementioned limits for variations in bending stiffness.

Catheter fatigue resistance

The conduit device described herein also advantageously provides effective fatigue resistance. For example, in the bending and torsional fatigue test method based on ASTM E2948, the conduit device described herein is able to withstand more than 20 cycles before fracture. The bending and torsional fatigue test method is described in more detail in document TM-00127, which is attached to this document as Appendix 1. In short, the test is adapted from ASTM E2948, a standard test method for measuring the rotational bending fatigue of a solid circular thin wire.

Effective fatigue resistance of the disclosed conduit device may exist along the entire length of the axial portion of the device, or along one or more sub-segments of the device (e.g., along one or more segments having a length of about 3 cm to 35 cm, or about 3 cm to 20 cm, or about 3 cm to 10 cm). Effective fatigue resistance is provided by one or more of the following parameters: (1) maintaining a ring width less than or equal to about 30% of the corresponding outer diameter of shaft 112; and/or (2) maintaining a cutting depth greater than or equal to about 11% of the outer diameter of shaft 112.

Example guidewire

As described above, the catheter device of this disclosure can be operated in combination with various guidewire devices to achieve the benefits described herein (e.g., by applying a thrust of 50g or less on the proximal portion of the catheter device, allowing the catheter device to advance within a tortuous path on the guidewire device).

Figures 10 through 20 illustrate components and aspects of example guidewires that can be used in conjunction with the catheter devices described herein. Although Figures 10 through 20 focus at least in some respects on guidewire devices including manually shaped tips and/or specific slit patterns, in view of this disclosure, it will be understood that guidewire devices used in conjunction with the catheter devices of this disclosure may include additional or alternative features and/or components.

Examples of guidewire features and components that can be used with the guidewires of the disclosed guidewire and catheter systems are described in U.S. Patent No. 11,369,351 (disclosing a distributed, incomplete ramp and serrated cut pattern for a guidewire cannula), U.S. Patent Application No. 2021/0228845 (describing a guidewire device in which the outer diameter of the cannula is larger than the outer diameter of the proximal section of the core and includes various coil constructions to provide alignment of the distal section of the core within the cannula), and U.S. Patent Application No. 2021/0346656 (describing a guidewire device having a high torsional stiffness to lateral bending stiffness ratio), the entire contents of each of the aforementioned patent applications are incorporated herein by reference.

Figure 10 illustrates an example guidewire assembly 200 with a core 202. A tube 204 is coupled to the core 202 and extends distally from attachment point 203 to the core 202. As shown, the distal section of the core 202 extends into and is surrounded by the tube 204. In some embodiments, the core 202 includes one or more tapered sections such that the core 202 can fit within and extend into the tube 204. For example, the distal section of the core 202 may be ground to gradually taper to a smaller diameter at its distal end. In this example, the core 202 and the tube 204 have substantially similar outer diameters at attachment point 203, where they are adjacent to and attached to each other. In some embodiments, the core 202 and the tube 204 have different outer diameters at attachment point 203, where they are adjacent to and attached to each other, and the difference in diameter is compensated by welding, solder, adhesive, interference fit, or other structural attachment methods.

The tube 204 is coupled to the core 202 in a manner that allows torsional forces to be transmitted from the core 202 to the tube 204 and thereby further distally through the tube 204 (e.g., using adhesives, brazing, and/or welding). The tube 204 can be coupled to the core 202 at the distal end of the device using medical-grade adhesive 220, forming a protective covering. As explained in more detail below, the tube 204 is micromachined to include multiple notches. The notches are arranged to form a notch pattern that advantageously provides effective formability near the distal tip of the guidewire device 200 while maintaining good torsionability. For clarity, the notch pattern is not shown in Figures 10 and 11. Figures 12 through 14 show examples of notch patterns that can be used for the tube 204.

The proximal segment 210 of the guidewire assembly 200 extends proximally for a length necessary to provide sufficient guidewire length for delivery to the target anatomical region. The proximal segment 210 typically has a length ranging from approximately 50 cm to 350 cm. The proximal segment 210 may have a diameter of approximately 0.014 inches, or a diameter ranging from approximately 0.008 inches to 0.125 inches. The distal segment 212 of the core 202 may taper to a diameter of approximately 0.002 inches, or a diameter ranging from approximately 0.001 inches to 0.050 inches. In some embodiments, the tube 204 has a length ranging from approximately 3 cm to 100 cm.

In some embodiments, the distal segment 212 of the core 202 tapers to a circular cross-section. In other embodiments, the distal segment 212 of the core 202 has a flat or rectangular cross-section. The distal segment 212 may also have another cross-sectional shape, such as another polygonal, oval, irregular shape, or a combination of different cross-sectional shapes at different regions along its length.

Typically, the user shapes the distal end of the guidewire device 200 by manually bending, twisting, or otherwise manipulating the distal (approximately) 1 cm to 3 cm of the guidewire device 200 into a desired shape. This length is schematically shown in Figure 10 as the distal “tip” 206. In some embodiments, the tip 206 comprises one or more formable components (within the tube 204) formed of stainless steel, platinum, and/or other formable materials. In a preferred embodiment, the tip 206 comprises one or more components formed of a material exhibiting work-hardening properties, such that the tip provides a higher modulus of elasticity at the shaped section during forming (i.e., plastic deformation) than before forming.

Figure 11 shows a cross-sectional view of the guide wire device 200 of Figure 10. As shown, the core 202 includes a proximal section 210 and a distal section 212, the distal section having a smaller diameter than the proximal section 210. A coil 214 is located on at least a portion of the distal section 212 of the core 202. The coil 214 is preferably formed of one or more radiopaque materials (such as platinum group metals, gold, silver, palladium, iridium, osmium, tantalum, tungsten, bismuth, dysprosium, gadolinium, etc.). Additionally or alternatively, the coil 214 may be formed at least partially of stainless steel or other materials capable of effectively maintaining their shape after being bent or otherwise manipulated by a user. In the illustrated embodiment, the coil 214 is located at or near the distal end of the device and extends proximally toward the attachment point 203. In some embodiments, the coil 214 has a length substantially consistent with the length of the tube 204. In other embodiments, the coil 214 is shorter. For example, coil 214 can extend from the distal end by 1, 2, 4, 6, 8, 10, 12, 15, 20, 25, 30 or 35 cm, or from the proximal end by a distance within the range defined by any two of the aforementioned values.

In some embodiments, coil 214 is formed as a single integral piece. In other embodiments, coil 214 comprises a plurality of separate segments positioned adjacent to each other and/or interlocked by interwoven coils. These separate segments may additionally or alternatively be brazed, adhered, or otherwise fastened to each other to form a complete coil 214. Some embodiments may include two or more coils, wherein at least one of the coils is configured to provide non-transmitting linearity, and at least one of the coils is configured to improve the alignment of the distal segment 212 of the core 202 within tube 204 in terms of size and shape.

Although the illustrated embodiment shows the space between coil 214 and tube 204, it should be understood that this is schematic for ease of observation. In some embodiments, coil 214 is sized to fill and pack a large proportion of the space between distal segment 212 and tube 204. For example, coil 214 may be sized to be close to both the distal segment 212 of core 202 and the inner surface of tube 204. Other embodiments include space between core 202 and tube 204 for at least a portion of the section where tube 204 and core 202 extend together for the guide wire device 200.

Coil 214 can be advantageously used to fill the space between core 202 and tube 204 so that the curvature of the distal segment 212 of core 202 is aligned with the curvature of tube 204. For example, when curvature is formed in tube 204, the tightly packed segment of coil 214 acts as packing between tube 204 and distal segment 212, imparting the same curvature to distal segment 212. Conversely, a guide wire arrangement omitting the coil, when bent at the tube, will not follow the same curve as the tube, but will extend until it is forced to bend after abutting against the inner surface of the tube.

The embodiments described herein advantageously allow the distal tip 206 to be shaped into a desired position and held in that position for a sufficiently long period of time. Compared to conventional wire guide devices, the illustrated embodiments are able to form and maintain the shaped configuration. With conventional wire guide devices, problems related to formability often arise due to performance mismatches between the tube structure and internal components (core and coil). The tube structure is typically formed from nitinol or other hyperelastic materials. When such a tube is bent or shaped, it tends to deviate towards its original (straight) position, thus exerting restoring forces on any formable internal components, resulting in deformation and loss of the customized shape of the tip.

Typically, for example, conventional guidewires have a shaped tip before deployment; however, during use, the shaped tip can be lost or degraded as the hyperelastic tube flexes towards an initial shape contrary to the desired tip shape. Therefore, restoring forces exerted by the tube act against the internal components, reducing or degrading the user-defined desired shape. In contrast, the embodiments described herein include the feature that allows tip 206 to be shaped without being subjected to overriding restoring forces from the tube. As described below, tube 204 may include a slit pattern that maintains effective torsion while also providing sufficient flexibility at the distal tip 206 to avoid disrupting the customized shape of tip 206.

Figures 12 to 16 illustrate exemplary embodiments of tube cut patterns that can be used in one or more of the guidewire device embodiments described herein. For example, the tube 204 of the embodiments shown in Figures 10 and 11 can be cut according to one or more of the structures shown in Figures 12 to 16.

Figure 12 illustrates a tube 504 with a series of cuts 508 forming (axially extending) beams 530 and rings 540 (extending laterally and circumferentially). In the illustrated embodiment, the cuts 508 are arranged on the tube as a series of “bypass cuts.” As used herein, a bypass cut is a cut that does not have a directly opposite cut relative to the longitudinal axis of the tube, thus leaving a single beam 530 of longitudinally extending material between the rings 540 of laterally and circumferentially extending material. The “bypass” cut pattern may also be referred to herein as a “single beam” cut pattern. The cross-sectional geometry of the beam can be of various shapes, including semicircular (such as those made by a cutting saw with a circular blade), flat-sided (such as those made by a laser processing operation), or any type of cross-sectional shape. In the illustrated embodiment, the cuts are arranged as alternating cuts offset by approximately 180 degrees along the length of the tube 504 from one cut to the next, but can also be made as rotationally offset at angles other than 180 degrees to 0 degrees, as described below.

As shown in the figure, the tube formed by cutting one or more sections using bypass (i.e., single beam) can offer numerous benefits, particularly regarding the associated shapeable tips of the guidewire assembly. For example, the tube with bypass cuts is relatively more flexible than a tube without cuts or with cuts leaving multiple beams between consecutive loops (e.g., assuming beam widths, loop sizes, and cut spacing are otherwise equal). Advantageously, the increased flexibility provided by the bypass cut arrangement minimizes or prevents the tube from deforming the shape of the guidewire's internal structure. For example, a core (e.g., stainless steel) disposed within the tube can be bent or flexed (i.e., plastically deformed) to provide the desired shape for the guidewire tip.

As mentioned above, in many cases, the force associated with the elastic recovery of the tube will be applied to the formed core and tends to straighten the formed core (at least relative to the portion of the formed core that is placed inside the tube). Therefore, properly adjusting the flexibility of the tube will reduce the recovery force applied to the formed core and allow the formed core to better maintain its shape.

In some embodiments, the depth of a series of bypass cuts or groups of bypass cuts gradually increases as each successive cut or group of cuts moves distally. Therefore, the cut depth distribution can be used to configure a tube for a given application with desired flexibility and torsion. For example, a tube configuration can include a proximal segment with relatively low flexibility and relatively high torsion, which rapidly progresses to a distal segment with relatively high flexibility and relatively low torsion as the bypass cuts rapidly deepen distally. In some embodiments, segments with relatively deep cuts are formed only at the distalmost segment of the tube where formability is expected or desired (e.g., 1 cm to 3 cm distal to the tube) to preserve higher torsion for the remainder of the tube.

The bypass incision 508 can vary in depth, width, and/or spacing. For example, as the incision 508 approaches the distal tip of the device, the incisions can become deeper and/or more closely spaced. Deeper and/or closer incisions provide relatively greater flexibility. Thus, a gradient can be formed that provides increasingly greater guidewire flexibility in regions progressively more distal to the guidewire. As described in more detail below, the bypass incisions 508 can also be arranged in alternating angular positions based on angular offsets applied at each adjacent incision or at adjacent groups of incisions. The illustrated embodiment shows a 180-degree angular offset from one incision to the next. Some embodiments may include angular offsets of approximately 5 degrees, 15 degrees, 30 degrees, 45 degrees, 60 degrees, 75 degrees, 80 degrees, or 85 degrees from one incision to the next or from one group of incisions to the next group of incisions.

Figure 13 illustrates another embodiment of tube 604, which has a bypass cutout and a set of opposing, depth-offset double-beam cutouts disposed proximal to the bypass cutout. In the illustrated embodiment, the set of bypass cutouts creates beam 630. Proximal to beam 630 is a set of cutouts arranged as opposing cutouts, which create beam 634. Although not visible in this view, additional beams are formed opposite each beam 634 (hidden behind beam 634 in this view). Thus, each ring 640 in the depth-offset double-beam cutout pattern has a set of two beams connecting the ring to its proximal adjacent ring and a set of two beams connecting the ring to its distal adjacent ring.

As shown in the figure, the opposing double beam cuts are offset in depth, so that for each pair of opposing cuts (one cut on each side of the tube axis), the depth of one cut is greater than the depth of the opposing cut. This depth-offset double beam cut can be advantageously used to transition from a bypass cut (as shown in Figure 12) to a non-offset opposing double beam cut (as shown in Figure 14).

Figure 14 shows a section of tube 250 with a double-beam cut pattern, where each cut in each opposite cut pair has approximately the same cut depth, resulting in beams that are substantially equidistantly spaced circumferentially. As shown, the cuts result in the formation of a pair of beams 234 between each ring 240. The cuts shown here are angled approximately 90 degrees from one opposite pair of cuts to the next pair of cuts, but other angle offsets may also be used.

Sections of a tube with a double-beam cutout pattern featuring beams spaced substantially circumferentially at equal intervals typically exhibit relatively high torque transmission capacity and relatively low flexibility, while sections of a tube with bypass cutouts typically exhibit relatively low torque transmission capacity and relatively high flexibility. The torque transmission capacity and flexibility of sections of a tube with a depth-offset double-beam cutout configuration generally fall between those of sections with depth-symmetrical, opposite double-beam cutouts and sections with bypass cutouts. The greater the difference in depth between the relative cutouts, the closer the resulting beams are in the circumferential direction, and therefore the more similar the offset double-beam cutout is to a single-beam/bypass cutout. Similarly, the more similar the depths of the relative cutouts, the more similar the offset double-beam cutout is to a symmetrical double-beam cutout.

Embodiments of the tube including the offset double-beam section advantageously provide a transition zone that can be positioned and configured to provide desired transition characteristics between the distal bypass cut area and the proximal symmetrical double-beam section. For example, depending on the length of the transition zone and/or the rapidity of the change in offset within the successive cuts, the transition zone can be relatively gentle or abrupt. Thus, the tube can be configured to provide a proximal section with greater torsion capability and less flexibility, transitioning to a more flexible distal section with greater flexibility to better maintain the bent shape during operator forming. The position and configuration of the proximal section, transition section, and distal section are adjustable to optimize the benefits of effective torsion capability and formable tip performance.

Figure 15 illustrates another embodiment of the tube 704, which has a single-beam cutout forming a plurality of beams 730 and rings 740. As shown, the cutout is arranged such that the beams 730 are aligned along one side of the tube 704, rather than being alternately positioned at 180 degrees or some other angular amount. Such an embodiment can advantageously provide preferential bending in one direction (e.g., toward the aligned beams 730), thereby further minimizing the associated restoring forces on the axis away from the tube.

Figure 16 illustrates an embodiment of tube 304 having an angular offset between a bypass cut pattern and a cut group. As shown, the angular offset causes the resulting beam 330 to be positioned along the length of the tube segment in a rotational/helical circumferential pattern. In some embodiments, a first angular offset is applied from one cut in a set of cuts to the next, and a second angular offset is applied from one set of cuts to the next set of cuts. For example, as shown in Figure 16, each cut 308 in a pair of adjacent cuts can be offset by approximately 180 degrees, leaving the formed beam 330 on opposite sides of each other relative to the longitudinal axis of the guidewire, while each pair (cuts) is offset from the adjacent pair (cuts) by some other angular offset (e.g., approximately 5 degrees in the illustrated embodiment). In this way, intra-set angular offsets can position the beam 330 on opposite sides of the guidewire axis, while inter-set angular offsets can adjust the angular position of the continuous beam to minimize the preferred bending direction of the guidewire over a segment of several sets of cuts 308.

Rotational offsets can also be applied to the cut patterns shown in Figures 12 through 15. In preferred embodiments, each consecutive cut or group of cuts (e.g., every two cuts, every three cuts, every four cuts, etc.) along the length of a given segment is rotated by approximately 1, 2, 3, 5, or 10 degrees, or in a double-beam construction by approximately 1, 2, 3, 5, or 10 degrees from 90 degrees, or in a single-beam construction by approximately 1, 2, 3, 5, or 10 degrees from 180 degrees. These rotational offset values have advantageously demonstrated a good ability to eliminate buckling deviations.

For example, in a double-beam cutout pattern, as shown in Figure 14, each pair of beams is equidistant in the circumferential direction. Rotational offsets of approximately 1, 2, 3, 5, or 10 degrees from 90 degrees along the length of the cutout section position every other pair of beams with a misalignment of a few degrees. For instance, the second pair of beams may be rotated slightly more or less than 90 degrees from the first pair, but the third pair will be rotated only a few degrees from the first pair, and the fourth pair will be rotated only a few degrees from the second pair. When several consecutive pairs of beams are arranged in this way along the length of the cutout section of the guidewire device, the resulting structure allows for enhanced flexibility in the cutout pattern without introducing or exacerbating any directional flexibility deviation.

The individual components and features of the pipe embodiments shown in Figures 12 to 16 can be combined to form different pipe configurations. For example, some pipes can be configured to have sections with bypass (single beam) cutouts (as shown in Figures 12, 15, and/or 16) and sections with symmetrically spaced double beam cutouts (as shown in Figure 14), and optionally also have one or more depth-offset double beam cutouts (as shown in Figure 13). For example, some pipe embodiments may include proximal sections with a symmetrically spaced double beam cutout pattern that transitions to distal sections with a bypass cutout arrangement.

The embodiments described herein advantageously enable the transmission of relatively greater torque in the proximal region of the tube, while reducing the torsionability of the distal section of the tube, to allow tip forming without excessively sacrificing torsionability. Therefore, the characteristics of the guidewire device can be tailored to specific needs or applications to optimize the operational relationship between torsionability, flexibility, and tip formability.

In a preferred embodiment, the formable distal section of the core has a stiffness sufficient to withstand the expected bending forces acting on the distal section of the core from the tube after the distal section of the core has been formed. In some embodiments, the formable distal section of the core is formed of one or more materials that provide an elastic modulus greater than approximately 1.5 to 4 times, or approximately 2 to 3 times, the elastic modulus of the material(s) used to form the tube.

Figure 17 illustrates an embodiment of a pipe 804 having a first segment 850, a second segment 860, and a third segment 870. The second segment 860 is located distal to the first segment 850, and the third segment 870 is located distal to the second segment 860. Each of the segments 850, 860, and 870 can be distinguished from each other by the cut pattern of each segment. As described above with reference to other embodiments described herein, the cut pattern can create rings 840 and beams 803 within the pipe. The segments 850, 860, and 870 shown in Figure 17 can have different cut patterns in each segment. For example, the first segment 850 can have a double-beam cut pattern, the second segment 860 can have a single-beam cut pattern, and the third segment 870 can have a double-beam cut pattern.

It is understood that other embodiments may include cut patterns different from those shown in FIG. 17. For example, in one embodiment, the first segment 850 may have a cut pattern with more than two beams, the second segment 860 may have a double-beam cut pattern or a single-beam cut pattern, and the third segment 870 may have a single-beam cut pattern or may be omitted. Furthermore, other embodiments of the tube 804 may include more or fewer than three segments along its length. For example, one embodiment of the tube 804 may include four or more segments. Additionally, for example, one embodiment of the tube 804 may include only one or two segments. Cut patterns shown in any other embodiment described herein may be used.

Figure 18A shows a side view of an embodiment of tube 904 similar to the tube shown in Figure 17. The tube in Figure 18A also shows a partial cross-sectional view of a second segment 960 to show the distal segment 912 of the core 902 extending through tube 904 and coil 914. Although only a partial cross-section is shown here, it should be understood that the core 902 typically extends all the way to the distal end 922 of the device. In the illustrated embodiment, the second segment 960 of tube 904 includes a single-beam cut-out pattern. The single-beam cut-out pattern creates a series of axially extending beams 930, each disposed between a pair of adjacent circumferentially extending rings 940.

In the illustrated embodiment, the continuous beams 930 alternate in position from the first side 916 to the second side 918 of the tube 904 (i.e., each continuous beam 930 has a rotational offset of approximately 180°). In another embodiment, the beams 903 of the single-beam cut-out pattern of the second segment 960 may all be positioned along the same side of the tube to form a backbone of aligned beams 930 extending axially along the tube 904 and connecting multiple rings 940, similar to the embodiment shown in Figure 15.

As shown in Figure 18A, the single-beam cut pattern of the second segment 960 forms a preferred bending plane B. As shown in Figure 18A, the preferred bending plane B extends axially along and laterally through the tube 904. Because the beam 930 of the second segment 960 extends axially together with the tube 904, the tube 904 is most flexible along the preferred bending plane B. That is, the beam 930 is configured such that the tube 904 offers minimal resistance to bending along the preferred bending plane B compared to any other plane. In this example embodiment, whether the alternating pattern of the beam 930 as shown in Figure 18A or the single main beam of the beam 930 as described above, the cut pattern of the second segment 960 produces the preferred bending plane B.

Furthermore, as shown in Figure 18A, the distal segment 912 of core 902 gradually tapers as the core extends distally through coil 914 and tube 904, gradually tapering into a flattened strip-like structure at the distal portion. Figure 18B shows a cross-sectional view of tube 904 through plane A-A of Figure 18A. The distal segment 912 of core 902 is a substantially flattened strip extending axially at least within the second segment 960 of tube 904. The strip-like structure of core 912 has a primary dimension D1 and a secondary dimension D2. The primary dimension D1 of the distal segment 912 of core 902 is greater than the secondary dimension D2 of core 902, such that the primary plane of the strip-like distal segment 912 of core 902 extends orthogonally to (and preferably perpendicular to) the preferred bending plane B. Thus, the bending resistance of the distal segment 912 of core 902 and tube 904 within the preferred bending plane B is also minimized. In other words, the core 912 can be gradually tapered into a strip structure and extend axially along the tube 904, such that the distal section 912 of the core 902 is aligned with the beam 930 of the second section 960, thereby sharing the preferred bending plane B with the tube 904.

In one embodiment, the length of the second segment 960 of tube 904 is from about 0.5 cm to about 5 cm. In another embodiment, the length of the second segment 960 of tube 904 is from about 1 cm to about 2 cm. In yet another embodiment, the length of the second segment 960 of tube 904 is from about 1 cm to about 1.5 cm. The distance the second segment 960 extends from the distal end 922 can vary depending on the length of tube 904, which may be bent or shaped for a given procedure. These distances can be varied between embodiments to accommodate various procedures if necessary. Other features of the embodiments shown in Figures 17-18B, including the materials and dimensions of coil 914, tube 904, and core 902, and including specific features related to the incision pattern, may be similar to other embodiments described herein with reference to other figures.

Figure 19 shows a close-up view of the transition between the first segment 950 and the second segment 960 of tube 904. In the illustrated embodiment, the first segment 950 includes a double-beam cut-out pattern, and the second segment 960 includes a single-beam cut-out pattern. The stiffness of tube 904 in each segment depends at least in part on the amount of material remaining in tube 904 after the cut and the amount of material remaining in the arrangement/spacing of the remaining beams 930. For example, all other things being equal, a segment of tube 904 having two beams 930 between each pair of adjacent rings 940 will have greater stiffness than a segment of tube 904 having a single beam 930 of the same size between each pair of adjacent rings 940. Furthermore, for example, all other things being equal, a segment of tube 904 with a greater distance between the cuts will have greater stiffness than a segment with a smaller distance between the cuts. In other words, the greater the distance between the cuts, the greater the thickness of the ring 940 formed between the cuts, and the greater the stiffness of the tube 904 in that section.

The cuts, rings 940, and beams 930 located at or near the transition point between the first segment 950 and the second segment 960 of the tube 904 shown in Figure 19 are configured such that the stiffness distribution of the tube 904 is approximately continuous over the transition between the two segments 950 and 960. In other words, the cut pattern of the first segment 950 and the second segment 960 is arranged to avoid significant jumps in stiffness from one side of the transition point to the other.

Of course, depending on the specific granularity level at which the stiffness is measured along pipe 904 and the specified length of the measured section, there can be some degree of discrete variation in stiffness between different measured sections. Since an infinite number of stiffness measurements cannot be performed, the practically measurable stiffness distribution will consist of stiffness levels measured at each of a series of discrete section lengths along the pipe. While the jumps (i.e., changes in stiffness) from one measured section to the next can be discrete, the overall pattern of such jumps preferably approximates a linear series or at least a smooth curve. Therefore, in the context of this disclosure, a “significant jump” occurs when the jump from one section to the next is greater than any immediately adjacent jump by more than about 1.5 times. Thus, significant jumps are avoided when there are no jumps at the transition points greater than any adjacent jump by more than about 1.5 times, and therefore the stiffness distribution at the transition points is “continuous.” Preferably, there are no jumps at the transition points greater than any adjacent jump by more than about 1.2 times.

Figure 19 illustrates an embodiment of a tube 904 having a ring 940 and a beam 930 that achieve a continuous stiffness distribution at the transition between segments 950 and 960. In the illustrated embodiment, the axial thickness of the ring 940a on the nearest side of the second segment 960 is greater than the axial thickness of the ring 940b on the farthest side of the first segment 950. In this way, the total amount of material in the tube 904 at the transition is similar between segments 950 and 960 at or near the transition. As described above, this results in continuous stiffness across the transition. Furthermore, the axial thickness of the ring 940 in the second segment 960 can decrease distally along the length of the tube 904, resulting in a corresponding decrease in stiffness. This is shown in Figure 19, but is more clearly shown in Figure 18A.

Turning now to Figure 20, the distal tip 906 of tube 904 is shown. The distal tip 906 shown in Figure 20 includes a third segment 970, at least a portion of the second segment 960, and a polymer adhesive 920 disposed distal to the third segment 970 at the distal end 922 of tube 904. The third segment 970 of tube 904 includes a double-beam cut-out pattern forming two beams 930 between each pair of adjacent rings 940. This contrasts with the single-beam cut-out pattern of the second segment 960. It should be understood that the transition between the second segment 960 and the third segment 970 can be analogous to the transition between the first segment 950 and the second segment 960 as described above. That is, the stiffness of tube 904 can be approximately continuous over the transition from the second segment 960 to the third segment 970.

Adhesive 920, located at the distal end 922 of tube 904, can extend between tube 904 and core at the distal end 922 of tube 904 to secure tube 904 and core together. As shown in FIG10, the distal section 212 of core 202 can extend distally beyond tube 204 and into adhesive 220. Adhesive 220 is thus capable of being used to connect tube 204 to core and/or coil 214.

Referring again to Figure 20, adhesive 920 may be disposed on the distal end 922 of tube 904 and at least partially wicked proximally into one or more cuts between the individual rings 940 and beams 930 of the third segment 970. Compared to the single-beam cut pattern of the second segment 960, the double-beam cut pattern of the third segment 970 provides an increased surface area of the tube 904 material to which adhesive 920 can bond. Therefore, the double-beam cut pattern of the third segment 970 provides a stronger bond between adhesive 920 and the distal segment of the core and/or coil. It should be understood that cut patterns including more than two beams 930 between each pair of adjacent rings 940 can thus be used to enhance the bond strength between tube 904 and the distal segment of the core 202 and/or coil. However, as mentioned above, the more material the cuts remove from tube 904, the less stiff tube 904 will be, and vice versa.

Furthermore, during manufacturing, applying a greater amount of adhesive 920 to the distal end 922 of tube 904 will cause the adhesive 920 to be further wicked proximally along tube 904. Due to the number and spacing of cuts in the cut pattern, the double-beam cut pattern of the third section 970 provides the manufacturer with an effective visual indication of how far the adhesive 920 is wicked proximally along the third section 970. This visual indication of the third section 970 can also help machines or other automated manufacturing equipment detect how far the adhesive 220 is wicked proximally along the third section 970 during manufacturing.

For example, when the manufacturer applies adhesive 920 to the distal end 922 of tube 904 during manufacturing, the adhesive can begin to wick through the space between ring 940 and beam 930 in the third section 970. Because the double-beam cutout pattern of the third section 970 provides a visual indication, the manufacturer can more easily discern how far the adhesive is wicked proximally from one ring 940 to the next along tube 904 compared to the single-beam cutout pattern of the second section 960. The manufacturer can therefore determine how much adhesive 220 is applied to the distal end 922 of tube 904. The manufacturer can also determine when to stop adding adhesive 220 based on a predetermined distance or predetermined ring 940 that the adhesive 920 has been wicked through.

In one embodiment, the third segment 970 of tube 904 extends from the distal end 922 of tube 904 by approximately 0.5 mm to 1.5 mm. In another embodiment, the third segment 970 of tube 904 extends from the distal end 922 of tube 904 by approximately 0.75 mm to 1.25 mm. In yet another embodiment, the third segment 970 of tube 904 extends from the distal end 922 of tube 904 by approximately 1 mm. The distance the third segment 970 extends from the distal end 922 can vary depending on the length of tube 904 that needs to be bent or shaped or the distance required for the adhesive 920 to fully wick along tube 904. These distances can vary between different embodiments as needed to accommodate various tubes and procedures. Other features of the embodiments shown in Figures 19 and 20, including the materials, properties, and dimensions of coil 914, tube 904, and core 902, may be similar to other embodiments described herein with reference to other figures.

Additional terms and definitions

Although certain embodiments of this disclosure have been described in detail with reference to specific constructions, parameters, components, elements, etc., such descriptions are illustrative and should not be construed as limiting the scope of the claimed invention.

As used herein, the term "micromanufacturing" refers to any manufacturing process capable of manipulating raw materials to form a conduit device having one or more of the features disclosed herein, including any manufacturing process capable of forming a gap in the inner shaft disclosed herein. Examples include, but are not limited to, laser cutting and blade cutting.

For any given element or component in the embodiments described, unless otherwise expressly or implied, any possible alternatives to that element or component may generally be used alone or in combination with each other.

Unless otherwise stated, the numbers used in the specification and claims to indicate quantities, components, distances, or other measurements should be understood as optionally modified by the term "about" or its synonyms. When the terms "about," "approximately," "substantially," etc., are used in conjunction with the stated quantity, value, or condition, they can be considered to refer to a quantity, value, or condition that deviates from the stated quantity, value, or condition by less than 20%, less than 10%, less than 5%, less than 1%, less than 0.1%, or less than 0.01%. At least, and without attempting to limit the application of the doctrine of equivalence to the scope of the claims, each numerical parameter should be interpreted according to the number of significant figures reported and by applying ordinary rounding techniques.

Any headings and subheadings used herein are for organizational purposes only and are not intended to limit the scope of the specification or claims.

It should also be noted that, as used in this specification and the appended claims, the singular forms “a,” “an,” and “the” do not exclude plural references unless the context clearly specifies otherwise. Thus, for example, embodiments referring to singular references (e.g., “part”) may also include two or more such references.

It will also be understood that the embodiments described herein may include the properties and features (e.g., components, parts, elements, components, and/or portions) described in other embodiments described herein. Therefore, various features of a given embodiment may be combined with and/or incorporated into other embodiments of this disclosure. Consequently, the disclosure of certain features relative to a particular embodiment of this disclosure should not be construed as limiting the application or inclusion of said features to that particular embodiment. Rather, it will be understood that other embodiments may also include such features.

Claims (20)

1. An intravascular system comprising: A catheter device configured for guiding through a blood vessel including one or more bends with a radius of curvature of 10 mm or less, wherein for at least a portion of the blood vessel, the ratio of the inner diameter of the blood vessel to the outer diameter of the catheter device is about 300% to about 800%; and A guidewire device configured to guide the wire through the blood vessel. The catheter device and guidewire device are configured such that the catheter device advances on the guidewire device in response to a thrust of 50g or less applied to the catheter device. 2. The intravascular system according to claim 1, wherein the path length of the blood vessel is at least 10 cm. 3. The intravascular system according to claim 1, wherein the path length of the blood vessel is at least 20 cm. 4. The intravascular system according to claim 1, wherein the one or more bends comprise three or more bends. 5. The intravascular system according to claim 1, wherein each of the one or more bends has a radius ranging from about 4 mm to about 9 mm. 6. The endovascular system of claim 1, wherein the catheter device is configured to advance on the guidewire device in response to a thrust of 40g or less applied to the catheter device. 7. The endovascular system of claim 6, wherein the catheter device is configured to advance on the guidewire device in response to a thrust of 30g or less applied to the catheter device. 8. The endovascular system of claim 7, wherein the catheter device is configured to advance on the guidewire device in response to a thrust of 20g or less applied to the catheter device. 9. The intravascular system of claim 1, wherein the ratio of the inner diameter of the blood vessel to the outer diameter of the catheter device is at least about 371%. 10. The intravascular system of claim 1, wherein the catheter device comprises: A micromanufacturing inner shaft having a plurality of gaps formed therein; and An external component comprising a polymer material disposed within the gap. 11. The intravascular system of claim 10, wherein the inner shaft comprises a plurality of axially extending beams connected to a plurality of circumferentially extending rings. 12. The intravascular system of claim 11, wherein the inner axis comprises one or both of a three-beam segment and a two-beam segment, wherein the three-beam segment is disposed proximal to the two-beam segment, and wherein at least a portion of the three-beam segment has a higher bending stiffness than the two-beam segment. 13. The intravascular system of claim 10, wherein the external component comprises a variety of different polymer stiffness measures. 14. The intravascular system of claim 13, wherein the external member includes a transition section in which a first polymer is adjacent to a second polymer of different hardness, the transition section including a variation in the bending stiffness of the external member, and wherein the microfabrication axis includes a section consistent with the transition section, the section being configured to compensate for the variation in the bending stiffness of the external member such that the overall variation in the bending stiffness of the catheter device at the transition section is less than the overall variation in the bending stiffness of the external member itself at the transition section. 15. The intravascular system of claim 14, wherein the second polymer is proximal to the first polymer and has a greater stiffness than the first polymer, such that the bending stiffness of the external member across the transition section in the distal-to-proximal direction increases, and wherein the bending stiffness of the shaft across at least a portion of the transition section in the distal-to-proximal direction does not increase to compensate for the increase in the bending stiffness of the external member. 16. The intravascular system of claim 10, further comprising an inner liner, the axis being positioned about the inner liner. 17. The intravascular system of claim 16, wherein the polymer material of the external member is fused to the liner, fills the gap of the shaft, and covers the outer surface of the shaft to encapsulate and embed the shaft. 18. The intravascular system of claim 10, wherein the shaft is formed of nitinol. 19. The endovascular system of claim 10, wherein the catheter device has a bending stiffness slope of no more than about 6.0 × ^10⁻⁷ ((N· ^m² )/cm) for the distal 15cm segment, a bending stiffness slope of no more than about 9.0 × ^10⁻⁷ ((N· ^m² )/cm) for the distal 35cm segment, and/or a bending stiffness slope of no more than about 9.0 × ^10⁻⁷ ((N· ^m² )/cm) for the distal 50cm segment. 20. The intravascular system of claim 1, wherein the guidewire device comprises: A core having a proximal segment and a distal segment; and A tubular structure connected to the core, such that a distal segment of the core enters the tubular structure, the tubular structure having a first segment and a second segment located distal to the first segment. The tubular structure includes a cut pattern that forms multiple axially extending beams, which connect multiple circumferentially extending rings.