Intravascular treatment site access

Abstract

To provide a system that is able to minimize or eliminate a gap between a guidewire and a guide catheter to prevent the catheter from getting stuck in the vasculature.SOLUTION: A microcatheter used to navigate through a blood vessel bifurcation region comprises: a first section; a second section distal to the first section, the second section outer diameter being larger than the first section outer diameter; and a distal tip distal to the second section, the distal tip outer diameter being smaller than the second section outer diameter; where the second section is configured to create an interface to minimize the open space between the microcatheter and a guide catheter that is on the outer peripheral side.SELECTED DRAWING: Figure 2

Description

Related Applications

[0001] This application claims priority to U.S. Provisional Application No. 62 / 293,522, filed February 10, 2016, entitled Intravascular Treatment Site Access, which is incorporated herein by reference in its entirety. BACKGROUND OF THE INVENTION

[0002] Guidewires are typically used in minimally invasive interventional procedures to access a treatment area. A guide catheter typically slides over the guidewire to access the target area and serves as a conduit for subsequently placed microcatheters and / or treatment / treatment devices.

[0003] The vasculature can be particularly tortuous or tortuous. This is especially true in the neurovasculature, where many small, tortuous vessels exist, making it extremely difficult to access and deliver therapeutic devices to target areas. In a phenomenon known as the ledge effect, gaps exist between the guidewire and the distal end of the guide catheter that can become trapped along vascular branches, preventing the catheter from effectively navigating the vasculature. The ophthalmic artery is an example of an area where there are branches and significant vascular tortuosity, and is one of many areas where a catheter can become clogged.

[0004] A system that minimizes or eliminates gaps between the guidewire and guide catheter is desirable to prevent the catheter from becoming stuck within the vasculature. Summary of the Invention

[0005] In one embodiment, a microcatheter having an enlarged distal section is described. The enlarged portion of the microcatheter is positioned adjacent to the inner diameter of the guide catheter to reduce any open space between the microcatheter and the guide catheter, and a guidewire can be placed through the microcatheter and used to guide the system. The microcatheter can include one or more marker bands to aid in precise alignment of the microcatheter relative to the guide catheter. After navigating the guide catheter and microcatheter to the appropriate treatment site, the microcatheter can be used to deploy various medical devices to treat the patient.

[0006] In one embodiment, the microcatheter with the enlarged distal section includes multiple marker bands to aid in visualization. The marker bands can be used to properly align the microcatheter with the guide catheter so that the enlarged distal section of the microcatheter coincides with the distal tip of the guide catheter. A guidewire is used to access the treatment site, and the microcatheter and guide catheter can be moved over the guidewire.

[0007] In one embodiment, an obstruction removal system is described. The obstruction removal system includes a guide catheter, a microcatheter delivered through the guide catheter and having an enlarged distal section, and an obstruction removal device delivered through the microcatheter. A guidewire is advanced through the microcatheter and is used to assist in advancing the microcatheter and guide the catheter near the treatment site. Once the treatment site is accessed, the microcatheter can be used to deliver an obstruction removal device, such as a clot retrieval device (e.g., a stent retriever), to remove an obstruction (e.g., a blood clot).

[0008] In one embodiment, a guidewire is described. The guidewire includes protrusions to minimize or eliminate gaps between the guidewire and the guide catheter. In one embodiment, the protrusions are bulbous. The protrusions can further include radiopaque markers to aid in imaging and placement of the guidewire.

[0009] In one embodiment, the guidewire includes a shapeable or malleable distal tip and a torque device. The shapeable or malleable distal tip can be bent in a specific direction, and the torque device clamps and secures the guidewire. The guidewire can then be rotated in a specific direction to align the distal tip with a specific blood vessel to aid in navigating the guidewire through the vasculature.

[0010] In one embodiment, a method of using a guidewire is described. The guidewire includes a distal protrusion and a radiopaque marker. The guide catheter also includes a radiopaque marker. The guidewire is retracted or the guide catheter is advanced so that the protrusion on the guidewire contacts the guide catheter. The guidewire and guide catheter can then be advanced together by pushing the guide catheter. The radiopaque markers on both the guide catheter and the guidewire are located on the same plane or adjacent to each other and are distinguishable by the user due to their enhanced radiopacity when viewed with a conventional imaging system. To aid in advancing the guidewire through the vasculature, the user can optionally use a torquer to lock and rotate the guidewire so that the distal tip is oriented in a specific direction.

[0011] In one embodiment, a rapid exchange system is described that minimizes the gap between the guidewire and the guide catheter in a scenario where the catheter is trapped at a vessel bifurcation and the rapid exchange system includes a distal enlarged section that travels over the guidewire to bridge the gap between the guidewire and the guide catheter. [Brief explanation of the drawings]

[0012] These and other aspects, features and advantages of embodiments of the present invention will become apparent and clear from the following description of embodiments of the invention, taken in conjunction with the accompanying drawings.

[0013] [Figure 1] FIG. 1 shows a conventional guide catheter getting stuck at a vessel bifurcation (a phenomenon known as the ledge effect).

[0014] [Figure 2] FIG. 2 illustrates a microcatheter having an enlarged distal section according to one embodiment, which can be used to address the problem of the ledge effect. [Figure 3] FIG. 3 illustrates a microcatheter with an enlarged distal section according to one embodiment, which can be used to address the problem of the ledge effect.

[0015] [Figure 4] FIG. 4 illustrates a guidewire having protrusions according to one embodiment.

[0016] [Figure 5] FIG. 5 illustrates a guidewire with protrusions and a guide catheter, according to one embodiment.

[0017] [Figure 6]FIG. 6 shows a torquer, a catheter, and a guidewire with protrusions used to manipulate the guidewire, according to one embodiment.

[0018] [Figure 7a] FIG. 7a shows a catheter having a radially reduced distal section, according to one embodiment. [Figure 7b] FIG. 7b shows a catheter having a radially reduced distal section, according to one embodiment.

[0019] [Figure 8] FIG. 8 illustrates a guidewire having wedge-shaped protrusions according to one embodiment.

[0020] [Figure 9] FIG. 9 illustrates a rapid exchange system disposed over a guidewire according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0021] Specific embodiments of the present invention will be described with reference to the accompanying drawings. However, the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. The terminology used in the detailed description of the embodiments shown in the accompanying drawings is not intended to be limiting of the invention. In the drawings, like numbers refer to like elements.

[0022] Many minimally invasive procedures utilize a guide catheter, also known as a distal access catheter (DAC), to access the area near the treatment site. A thin, flexible guidewire is advanced through the vasculature, and the guide catheter / DAC is advanced over the guidewire to access the treatment site. Once the area is accessed, a microcatheter is placed through the guide catheter, and the guidewire is withdrawn. The microcatheter is then used to aid in and deliver a therapeutic or treatment agent, such as a stent, a clot retrieval device, or a coil used to fill an aneurysm. Guide catheters typically have a relatively large diameter because they must accommodate both the guidewire and the microcatheter. Navigating a guide catheter through the vasculature is challenging due to the complex nature of the anatomy. This is particularly true in the brain or neurovasculature, where vessels are small, convoluted, and rich in branching vessels, making it difficult to navigate the catheter to the appropriate treatment site.

[0023] At a vessel bifurcation, a navigational obstacle can arise due to a gap between the guidewire and the distal end of the guide catheter, potentially causing the distal end of the guide catheter to become stuck at the bifurcation. This phenomenon, known as the ledge effect (see FIG. 1 ), results in a gap 6 between the guidewire 4 and the guide catheter 8 becoming trapped at the vessel bifurcation 5. In one example, a typical guide catheter 8 has an inner diameter of 0.07 inches, and the guidewire 4 has a diameter between 0.014 inches and 0.035 inches. The gap size 6 (defined as the radius of the guide catheter 8 minus the radius of the guidewire 4) typically ranges between 0.0175 inches and 0.028 inches. This gap size 4 represents between 25 and 40% of the overall guide catheter inner diameter, representing a significant amount of open space. Guide catheter migration problems can delay or even prevent treatment, increasing patient risk. The following embodiments address this issue.

[0024] US2016 / 0022964 to Goyal, entitled "System and Method for Intracranial Vascular Access," discloses a guidewire-based system that addresses the complexities of the ledge effect with a guidewire having an enlarged region designed to bridge the gap between an outer circumferential guide catheter and an inner circumferential guidewire. US2016 / 0022964 is incorporated herein by reference in its entirety.

[0025] 2-3 and the following disclosure relate to an intermediate microcatheter 10 having an enlarged region 14 that minimizes any gap between the guidewire 22 and the outer guide catheter 38 located outside the guidewire. In other words, the intermediate microcatheter 10 slides over the guidewire 22, with its enlarged distal end 14 occupying open space within the lumen of the outer guide catheter 38. When the enlarged region 14 is positioned at or slightly beyond the distal end of the outer guide catheter 38, the "ledge" created by the outer guide catheter 38 is reduced or eliminated, thereby avoiding capture at vessel bifurcations and other vessel geometries. Additionally, several embodiments described later herein (see FIGS. 4-9) disclose improved guidewire-based systems in which the guidewire has an enlarged region that bridges the gap between the outer guide catheter and the guidewire.

[0026] FIG. 2 shows a microcatheter 10 having an expanded or enlarged distal section 14. The expanded or enlarged distal section 14 can have a generally cylindrical shape with a tapered end, a longitudinally rounded shape, or any other general shape. Although the distal section 14 is enlarged, the inner diameter defining the lumen 12 in the microcatheter 10 preferably remains constant throughout the entire length of the microcatheter 10. Preferably, the expanded or enlarged distal section 14 of the microcatheter 10 exactly matches or is slightly smaller than the inner diameter of the outer circumferential guide catheter 38. As seen in FIG. 3, this close fit of the enlarged distal section 14 bridges or fills the gap between the intermediate microcatheter 10 and the guide catheter 38, creating a conforming interface between the two catheters and preventing any open, exposed surfaces that could otherwise become trapped in a vascular bifurcation. For example, the inner diameter of the outer guide catheter 38 is approximately 0.070 inches, and the diameter of the enlarged distal section 14 is approximately 0.067 inches. This reduces the gap size 26 to approximately 0.0015 inches on all sides. This contrasts with the gap size 6 between the guidewire 22 and the outer guide catheter 38, which is approximately 0.0175 to 0.028 inches on all sides (using a 0.014 to 0.035 inch guidewire). A gap size of 0.0015 inches is only approximately 2% of the total inner diameter of the outer guide catheter 38. In another example, the enlarged distal section 14 has a diameter that is approximately the same diameter as the inner diameter of the guide catheter 38. In either of these two examples, the diameter of the enlarged distal section 14 is close to the inner diameter of the outer guide catheter 38, and the limited open space does not provide sufficient space for capture by the blood vessel. The expansion / divergence section 14 may have a linear taper 20 as shown in FIG. 2, or the shape of the taper may be rounded or elliptical.To minimize the gap between the inner diameter of the microcatheter 10 and the guidewire 22, the distal tip 18 of the intermediate microcatheter 10 preferably maintains approximately the same inner diameter size as the proximal portion of the intermediate catheter 10 (i.e., relatively close or in close proximity to the guidewire 22).

[0027] In another embodiment, the inner diameter of the lumen of the microcatheter 10 is larger within the enlarged region 14. However, in this embodiment, to prevent any openings trapping the surface between the blood vessel and the microcatheter 10, it is desirable that the distal tip 18 of the microcatheter 10 have a relatively reduced inner diameter, eliminating any large gaps between the guidewire 22 and the intermediate microcatheter 10.

[0028] Distal and proximal marker bands 16a, 16b are positioned on the microcatheter body 11 at the distal and proximal ends of the enlarged distal section 14, respectively, to aid in visualizing the position of the intermediate microcatheter 10 (particularly the distal section of the microcatheter 10). In one embodiment, a third marker band (not shown) can be positioned at the distal tip 18 of the intermediate microcatheter 10, beyond the enlarged distal section 14, so that the distal tip 18 of the device is visible within the patient.

[0029] In one example of a bulbed intermediate microcatheter 10 of the present invention, the outer guide catheter 30 has an inner diameter of approximately 0.07 inches, the enlarged distal section 14 of the intermediate microcatheter 10 has an outer diameter of approximately 0.067 inches, the region of the microcatheter body 11 proximal to the enlarged section 14 has an outer diameter of approximately 0.033 inches, and the distal tip 18 has an outer diameter of approximately 0.031 inches. The smaller outer diameter of the distal tip 18 promotes improved flexibility and trackability, while the larger outer diameter of the proximal section of the microcatheter body 11 promotes increased pushability. The inner diameter of the intermediate microcatheter 10 is constant at approximately 0.021 inches. These dimensions may vary based on the guidewire or guide catheter used. For example, the outer diameter of the intermediate microcatheter 10 ranges from approximately 0.013 inches to approximately 0.073 inches, the length of the enlarged section 14 is from approximately 0.5 cm to approximately 3 cm, and the length of the distal tip 18 is from approximately 0.5 cm to approximately 6 cm. The inner diameter of the intermediate microcatheter 10 is constant throughout its length, ranging from about 0.01 inches to about 0.045 inches. The working length of the intermediate microcatheter 10 is about 148-168 cm. If desired, a lubricious coating can be used on the outer surface of the enlarged section 14 of the intermediate microcatheter 10.

[0030] The intermediate microcatheter 10 can be manufactured in a variety of ways. In one example, the inner liner of the intermediate microcatheter 10 is composed of PTFE, LDPE, LLDPE, or HDPE. A stainless steel coil is disposed on the outer periphery of the inner liner and is either about 0.00075 inches to about 0.0015 inches of coiled wire or flat-wound wire. A stainless steel flat wire or braid is disposed on the outer periphery of the coil. An outer shaft layer can be disposed on the outer periphery of the reinforcement material and can include different durometers and different types and amounts of material, for example, Shore hardnesses ranging from 10A to 72D. Generally, it is desirable to have higher stiffness at the proximal end and higher flexibility at the distal end; therefore, the outer layer proximal section generally includes a stiffer material than the outer layer distal section. One or two platinum / iridium (90% / 10%) marker bands are placed on the inner circumferential surface of the bulb for visualization, with additional marker bands placed at the distal tip 18 of the intermediate microcatheter 10. The enlarged outer diameter region 14, which contains the bulb, is made of a relatively soft polymer material, such as polyblend 18A, 30A, balloon, or any Shore A durometer material. This softness aids in navigation through the guide catheter 38 and flexibility in scenarios where the inner diameter of the outer guide catheter 38 closely matches the outer diameter of the bulbed section 14, or where the bulbed section 14 comes into contact with a portion of the vessel and the soft material helps prevent vessel trauma (e.g., at a vessel bifurcation).

[0031] The microcatheter 10 can utilize a lubricious coating along its entire length or selectively along specific sections to enhance the trackability of the microcatheter. Lubricious coatings are particularly useful in the expansion region 14 of the microcatheter 10 because the expansion region 14 is the largest cross-sectional area of ​​the microcatheter 10 and is also the portion of the microcatheter most likely to come into contact with the outer circumferential surface of the guide catheter 38. In one example, the lubricious coating is hydrophilic and can utilize multiple layers (e.g., a well-adhering base coat layer formed from a crosslinking agent and a highly lubricious top coat layer chemically bonded to the base coat layer).

[0032] The guide catheter 38 typically utilizes a marker band 40 located approximately 3 cm from its distal tip, allowing the user to visualize the distal tip within the patient (see FIG. 3). The user moves the microcatheter 10 through the guide catheter 38 so that the dilated / expanded region 14 of the intermediate catheter 10 is positioned flush with the distal tip of the outer guide catheter 38, as shown in FIG. 3. This ensures that there is no or minimized gap between the guide catheter 38 and the microcatheter 10. This minimized gap is shown as element 26, while proximal gap 36 reflects the gap between the guide catheter 38 and the reduced proximal portion of the microcatheter 10. Proximal gap 36 can be considered the normal gap between the microcatheter and the guide catheter in scenarios where a typical microcatheter is used rather than an expanded microcatheter. As previously mentioned, gap 6 represents the typical gap that exists between the guidewire 22 and the guide catheter 38 in a typical procedure in which the guide catheter is moved directly over the guidewire.

[0033] The expanded intermediate microcatheter 10, as previously described, acts as an intermediary between the guidewire 22 and the guide catheter 38. When the intermediate microcatheter 10 is properly positioned as shown in FIG. 3, the user will see a line of marker bands: the microcatheter distal marker band 16a, the outer guide catheter 3 cm marker band 40, and the proximal marker band 16b. Each of these marker bands can be either a series of separate segments (one for each marker band) with gaps between them, or an elongated and continuous segment. This line of marker bands ensures precise alignment, so the user knows that the enlarged distal section of the microcatheter 10 has passed the distal tip of the guide catheter 38, such that the enlarged section 14 of the microcatheter 10 occupies space within the guide catheter 38. Once the user confirms this, they can proceed with advancing the guidewire, the intermediate microcatheter over the guidewire, and the guide catheter over the intermediate microcatheter.

[0034] Because the intermediate microcatheter 10 is used as a bridging device between the guidewire 22 and the guide catheter 38, a small gap 30 also exists between the guidewire 22 and the microcatheter 10. It is desirable not to completely eliminate this gap 30 to avoid friction between the guidewire 22 and the intermediate microcatheter 10. However, this gap 30 is relatively small and therefore will not be trapped by a vascular bifurcation. In one example, the microcatheter 10 has a constant inner diameter of approximately 0.021 inches and accommodates a guidewire 22 sized between 0.014 inches and 0.018 inches. Applying the above-described formula for gap size, subtracting the radius of the inner element (here, the guidewire 22) from the radius of the outer element (here, the microcatheter 10), the gap size between the microcatheter and the guidewire is approximately 0.00205 inches to approximately 0.0035 inches. If the microcatheter were not used at all as described above, the gap size could range from approximately 0.0175 inches to 0.028 inches. In other words, the gap size is reduced to approximately 7-20% of its initial value simply by using the microcatheter. The use of an expanded microcatheter as described above further reduces the gap between the microcatheter and the surrounding guide catheter. Therefore, the advantage of using the expanded microcatheter 10 as an intermediate element between the guidewire 22 and the guide catheter 38 is twofold. First, it minimizes the gap that typically exists between the guidewire and the guide catheter. Second, the presence of the expanded / expanded section 14 of the microcatheter 10 minimizes the gap between the microcatheter 10 and the guide catheter 38. Reducing or minimizing the gap minimizes the amount of open space that can be trapped in vascular bifurcations, which in turn substantially enhances the device's trackability through complex anatomy.

[0035] Alternate embodiments may utilize an expanding intermediate microcatheter 10 with more or fewer marker bands. In one example, the expanding intermediate microcatheter 10 may use three marker bands, with the third intermediate marker band located between the distal marker band 16a and the proximal marker band 16b. This intermediate marker band aligns with the guide catheter 3 cm distal tip marker 40. Such an embodiment would be most useful for larger microcatheters with elongated expansion regions 14, as the presence of so many marker bands may make them difficult to see individually. In another example, the intermediate microcatheter 10 may use one marker band, with the microcatheter marker band aligning with the guide catheter distal tip marker band 40 to ensure proper positioning of the intermediate microcatheter.

[0036] In one method of use, the guidewire 22 is advanced through the patient's blood vessels, and the guide catheter 38 is advanced over the guidewire 22. As the guidewire 22 advances through the vessel bifurcation, the user advances the expanded intermediate microcatheter 10 over the guidewire 22. This advancement is performed so that the microcatheter 10 is positioned in the distal region of the guide catheter 38 and extends from the distal tip of the guide catheter 38. At this time, the distal tip 18 of the intermediate microcatheter 10 is positioned distal to the outer guide catheter 38, and the expanded region 14 of the intermediate microcatheter 10 bridges the gap between the guidewire 22 and the guide catheter 38. To achieve the desired position, the intermediate microcatheter 10 has two marker bands 16a and 16b, as shown in Figures 2-3. The user manipulates the intermediate microcatheter 10 so that the two marker bands 16a and 16b are positioned on either side of the guide catheter 3 cm distal tip marker band 40. The user moves the intermediate microcatheter 10 and guide catheter 38 together as a unit over the outer surface of the guidewire 22 through the bifurcation region by pushing both simultaneously.

[0037] In another embodiment, the expanding intermediate microcatheter 10 is used as part of an implant delivery system. The expanding microcatheter 10 addresses the problem of the ledge effect while also being used as a conduit for delivering an implant, such as a stent, clot retrieval device, or embolic coil. After the intermediate microcatheter 10 is advanced to the treatment site using a guidewire 22, the guidewire 22 is withdrawn through the intermediate microcatheter 10. The intermediate microcatheter 10 is then used to deliver the implant.

[0038] In one embodiment, the expanding intermediate microcatheter 10 is part of a clot retrieval system. Blood clots can cause problems, such as ischemic stroke, due to reduced blood flow to areas distal to the clot. A clot retrieval device is a mechanical structure designed to grasp, retain, and remove a clot from the vasculature. U.S. Pat. No. 9,211,132, entitled "Obstruction Removal System," discloses a clot retrieval device and is incorporated herein by reference in its entirety. A stent retriever is a type of clot retrieval device that takes the form of a single tubular wire mesh or cylindrical laser-cut sheet element designed to retain a clot. U.S. Pat. Nos. 8,679,142, 8,357,179, and 6,402,771 further disclose stent retriever devices and are incorporated herein by reference in their entirety.

[0039] In one embodiment, the dilating intermediate microcatheter 10 is part of a clot retrieval system. In another embodiment, the dilating microcatheter 10 is used as part of a stent retriever system. The dilating intermediate microcatheter 10 addresses the problem of the ledge effect. Here, the system helps the clot retriever access problem areas (e.g., bifurcation areas in the neurovasculature). The system includes a guide catheter 38, an intermediate microcatheter 10, a guidewire 22, and a clot retriever or stent retriever (not shown). The guide catheter 38 is structurally more rigid than the microcatheter 10 and navigates through most of the vasculature to the general area of ​​the delivery procedure. The intermediate microcatheter 10 is smaller than the guide catheter 38 and is delivered through the guide catheter to access the actual treatment site, thereby providing a conduit to the treatment site. The guidewire 22 helps navigate the microcatheter 10 and guide catheter 38 through the vasculature to access the treatment site. The delivery procedure is similar to that described above, with the microcatheter being advanced over the guidewire and positioned beyond the distal tip of the guide catheter to allow delivery of the system through the vessel bifurcation area. Once the system is properly positioned, the guidewire 22 is withdrawn through the expanded intermediate microcatheter 10, and the microcatheter 10 is used as a conduit for a clot retriever or stent retriever.

[0040] In one embodiment, a clot retrieval device or stent retriever is pre-fed through an expanded intermediate microcatheter 10 into the distal section of the intermediate microcatheter 10, with the distal end of the clot retriever device or stent retriever positioned flush with or beyond the distal end of the intermediate microcatheter 10. The intermediate microcatheter 10 is housed within a guide catheter 38, similar to FIG. 3 . The outward force provided by the clot retrieval device can be used to aid in navigating the catheter and stent retriever through vessel bifurcation areas and complex anatomical structures. That is, the force exerted by the clot retrieval device on the microcatheter can help orient the system in a specific direction at a vessel bifurcation and can also help direct the system through complex anatomical structures.

[0041] In some embodiments, the expanding intermediate microcatheter 10 is used for movement of the guide catheter 38 without the guidewire 22 and is subsequently used for delivery of the therapeutic material. The distal section 14 of the expanding intermediate microcatheter 10 is preferably coated with a lubricious coating that reduces friction through the guide catheter 38 and promotes smooth movement through the vasculature. Furthermore, because the distal inner diameter of the expanding intermediate microcatheter 10 is significantly smaller than the inner diameter of the outer guide catheter 38, there is less open luminal surface that can become trapped in vascular bifurcations.

[0042] In some embodiments, the guidewire 22 is deployed first, and then the dilatation microcatheter 10 is moved over the guidewire 22, while the guide catheter 38 is moved separately over the guidewire 10. In some embodiments, the guidewire 22 is deployed first, while the dilatation microcatheter 19 and the guide catheter 38 are simultaneously and together deployed over the guidewire.

[0043] Another possible embodiment used to address the ledge effect problem utilizes a guidewire with an enlarged region that bridges the gap between the guidewire and the guide catheter. For example, the guidewire 110 shown in FIG. 4 has a radial projection 116 at its distal end that radially bridges the gap within the guide catheter 38. In this regard, the intermediate microcatheter with an enlarged distal end described in the previous embodiment is not required.

[0044] The radial protrusions 116 are disposed within the distal section 110b of the guidewire 110 and can have many shapes, including ellipsoidal, oval, circular, expanded, or diamond-shaped. In one particular example, the protrusions 116 are expanded. The protrusions 116 are preferably made of a soft polymer material to facilitate movement through the patient's blood vessels. A soft polymer is less rigid and more malleable than a hard polymer, reducing the likelihood of the radial protrusions 116 bouncing or jerking when they contact the vessel wall. To prevent any large, unexpected movements, the protrusions 116 also preferably slide against the vessel wall rather than bouncing. The smooth transition created by the taper 116a at the protrusions 116 further prevents the guidewire 110 from bouncing after contacting the vessel wall within the vasculature.

[0045] The protrusions 116 further include radiopaque markers 118, which in one example are circular marker bands disposed around the polymeric radial protrusions 116. The marker bands may include platinum, tantalum, palladium, gold, or any similar high density metallic element, alloy, or compound that is visible by imaging techniques.

[0046] Distal section 110b of guidewire 110 also includes tapered section 132, reduced diameter section 134, and coil 117 disposed on the outer circumferential surface of reduced diameter section 134. Coil 117 is composed of two distinct coil elements: a first, non-radiopaque coil portion 114 (made of stainless steel in one example) and a second, radiopaque coil portion 122 (made of platinum in one example) useful for imaging and viewing the distal section of the catheter. Coil 117 provides a soft contact surface and aids in flexibility to avoid vascular trauma if the guidewire tip strikes a vessel wall.

[0047] The guidewire 110 also includes a distal tip 120 shaped to aid in advancing the guidewire through the vasculature. A shaping mandrel can be used to help shape the distal tip 120 of the guidewire 110 (to curve the distal tip in a particular direction). Guidewire shaping mandrels are currently used to pre-shape the distal tip of guidewires. These shaping mandrels are typically packaged with the guidewire, and the user uses the mandrel to impart a curved shape to the distal tip of the guidewire before placing the guidewire within the patient's vasculature. The curved shape is useful for adapting the guidewire for navigation through the vasculature. The user can rotate the guidewire to align the curved tip with the user's desired guidewire advancement direction, for example, at a vessel bifurcation, to aid in the advancement of the catheter and guidewire moving around the guidewire's outer periphery through complex anatomical structures.

[0048] Guidewire 110 is preferably tapered such that its proximal section 110a has a larger diameter than its distal section 110b. This tapered shape aids torque response; torque generated by torqueing the proximal end of the system is easily transferred through guidewire 110, providing sufficient torque response at the distal tip 120 of guidewire 110. In one example, guidewire 110 has a proximal diameter 112 of about 0.013 inches to about 0.014 inches, and in a more specific example, a diameter of about 0.0135 inches. This diameter may be slightly tapered or may be substantially constant. Guidewire 110 has a distal section diameter 124 of about 0.012 inches. Distal section diameter 124 refers only to the diameter of distal coil 117, including coil elements 114 and 122.

[0049] 4-6 illustrate an optional docking element 130. The docking element 130 is positioned proximal to the guidewire 110 and functions as a proximal guidewire extension, allowing the physician to better grasp the guidewire 110, thus increasing the ease of advancing, retracting, and torque- ing the guidewire 110. In one example, the docking element 130 is a proximal wire, with the guidewire 110 constructed around the distal section of the docking element 130. Here, the docking element 130 terminates within the proximal section of the guidewire 110.

[0050] In one example, proximal section 110a of guidewire 110 is constructed from a stainless steel core wire, and distal section 110b of guidewire 110 (including tapered section 132 and reduced diameter section 134) is constructed from a nitinol core wire.

[0051] In one example, guidewire 110 is approximately 200 centimeters long. The stainless steel core wire, including proximal section 110a, extends approximately 140 centimeters, and the stainless steel core wire, including distal section 110b, extends approximately 60 centimeters. Stainless steel coil 114 extends approximately 37 centimeters, while platinum coil 122 covers approximately 3 centimeters. Shaped length section 120 extends approximately 1.4 centimeters. The hydrophilic coating on the distal section of guidewire 110 extends approximately 140 centimeters (covering the distal portion of the guidewire and extending to the distal tip of the guidewire).

[0052] 5-6 show the guidewire 110 of FIG. 4 positioned within the guide catheter 38. In FIG. 5, the guidewire 110 exhibits protrusions 116 and radiopaque markers 118, with the distal portion of the guidewire 110 positioned beyond the distal end of the guide catheter 38. In this configuration, the guidewire is used to gain access near the target treatment site, and then the guide catheter 38 is advanced or moved over the guidewire 110.

[0053] In FIG. 6 , the guidewire 110 is pulled back into the guide catheter 38, or the guide catheter 38 is pushed over the guidewire 110. This is done so that the protrusions 116 are in intimate contact with the guide catheter 38 (e.g., the protrusions 116 are undersized relative to the lumen of the guide catheter 38, or slightly oversized but made of a malleable material that can be deformed and pulled into the catheter 38). Alternatively, a combination pushing / pulling technique can be used. If the protrusions 116 have an expanded shape as shown in FIGS. 4-6 , the guide catheter 38 should contact the area of ​​the protrusions 116 with the largest diameter. The guide catheter 38 includes a radiopaque marker 127. The guidewire radiopaque marker 118 is positioned flush with the guide catheter radiopaque marker 127, or the guidewire radiopaque marker 118 is positioned just distal to the guide catheter radiopaque marker 127. In any event, the presence of the two radiopaque elements in close proximity to one another increases the visualization of the system when viewed by a user, so the user knows that the two elements are aligned and that the guidewire 110 is compatible with the guide catheter 38, allowing the system to be pushed through the vasculature.

[0054] When the guidewire projections 116 contact the guide catheter 38, there are substantially no gaps between the guidewire 110 and the guide catheter 38. This helps mitigate the ledge effect, as there are substantially no gaps or open surfaces for the blood vessel to get caught on. Typically, the presence of gaps creates voids where the guide catheter can get stuck. However, when the guidewire projections 116 are mated with and positioned on the guide catheter 38, there are no such gaps, and the projections slide against the blood vessel, preventing the guide catheter from getting caught at the vessel bifurcation. As previously mentioned, the projections preferably include a soft polymer to promote a sliding effect when the projections contact the blood vessel. An additional hydrophilic coating, an additional lubricious coating, or a lubricious polymer can be used to enable the projections to slide against the blood vessel wall.

[0055] The guidewire 110 of FIGS. 4-6 can be advanced in several different ways. In a first method, the guidewire 110 is deployed distally of the guide catheter 126, and the guide catheter 38 is pushed over the outer surface of the guidewire 110. If the guide catheter 38 becomes trapped (e.g., due to a ledge effect), the guidewire 110 is retracted so that the guidewire projection 116 contacts the guide catheter 38. The guide catheter 38 is then pushed forward, and both the guidewire 110 and the guide catheter 38 advance as a unit. Because the guide projection 116 contacts the guide catheter 38, as the guide catheter 38 advances, the guidewire 110 also advances. In a second method, the user places the guidewire projection 116 on the distal section of the guide catheter 38, and the guidewire 110 and the guide catheter 38 are advanced together as a unit through the vasculature. Once the guide catheter 38 is properly positioned, a microcatheter can be advanced through the guide catheter and the guidewire 110 withdrawn, and the microcatheter can be used to deliver a therapeutic agent (e.g., a stent, coil, clot retrieval device), or the guide catheter 38 itself can be used to deliver a therapeutic agent.

[0056] As discussed above with respect to embodiments of the dilatation microcatheter 10, a small gap may be tolerated as long as it is too small to be trapped in a vessel bifurcation. Thus, some embodiments may utilize a small gap between the guidewire protrusion 116 and the guide catheter 38 such that the protrusion 116 does not necessarily contact the guide catheter 38.

[0057] FIG. 6 shows a torquer 128 used to lock and torque the guidewire 110. The torquer 128 includes a pushable collet that pushes down on the guidewire 110 to lock it in place. The torquer 128 can be twisted or rotated to push the collet in and lock the guidewire 110. Alternatively, the torquer 128 can include a movable element linked to the collet and lock the guidewire 110 via the collet. FIG. 6 shows the torquer 128 applied to the proximal section of the guidewire 110. The torquer 128 is used to lock the guidewire 110. Thus, the guidewire distal tip 120 is in a fixed position relative to the torquer 128. The user locks the guidewire 110 and then pushes the guidewire 110 through the vasculature. Because the guidewire 110 is locked in place via the torquer 128, the direction of the curved distal tip 120 does not change unless the torquer 128 is rotated. Torquers 128 allow for locking the orientation of guidewire 110 while pushing and advancing the guidewire through the vessel, preventing accidental rotation of guidewire 110. If the user becomes stuck at a bifurcation and wants to change the direction of guidewire 110, the user can rotate torquers 128, which rotates guidewire 110 and reorients guidewire distal tip 120 to align it in a different direction.

[0058] In other embodiments, the guidewire protrusion 116 can selectively lock to the guide catheter 38. In one example, the protrusion 116 can include a threaded element that threads into a corresponding groove in the guide catheter 38, thereby locking the two elements together similar to a screw. In another example, the protrusion 116 can include an enlarged ring that mates with a corresponding recess in the guide catheter 38. In another example, the guidewire protrusion 116 includes a recess, and the guide catheter 38 includes a protruding ring that mates with the recess. Engagement is achieved by force, whereby the elements engage (lock) and separate (unlock) with one another when the user applies sufficient force. In one example, a torquer similar to that described above can be used to lock the guidewire 110 to the guide catheter 38 when the two elements contact or engage with one another.

[0059] The foregoing description discusses the advantages of soft polymers used for the guidewire projections 116. Here, one advantage is that the material properties of the soft polymers promote a sliding contact interface between the guidewire projections 116 and the blood vessel. Another advantage of soft polymers used for the projections is their malleability. When the guidewire 116 is withdrawn, the user can retract the guidewire 116 through the guide catheter 38. The malleability of the soft polymer allows the guidewire projections 116 to be pushed and easily retracted through the guide catheter 38.

[0060] In one embodiment, the guidewire protrusions 116 comprise a soft plastic polymer (e.g., a single piece of polymer with holes through which the guidewire passes). Alternatively, the polymer protrusions can be pushed onto the outer periphery of the guidewire 110. Alternatively, the protrusions can be manufactured separately and attached to the outer periphery of the guidewire 110 via an adhesive. The protrusions 116 can have a number of shapes, as discussed above. In particular, the shape of the side surface affects how the protrusions 116 contact the vessel wall. Example shapes for the protrusions 116 include a gently conical shape, as shown in FIG. 8 as element 116a, or a concave or convex rounded shape.

[0061] In one example, proximal portion 110a and distal portion 110b of guidewire 110 are manufactured separately. Protrusions 116 are disposed on the outer periphery of distal portion 110b of guidewire 110 using any of the techniques described above. Distal portion 110b and proximal portion 110a of guidewire 110 are then mated using various techniques, such as heat treatment, adhesives, soldering, welding, etc. In another example, guidewire 110 is manufactured as a single unit, and protrusions 116 are disposed on the outer periphery of the distal portion of guidewire 110 using any of the techniques described above.

[0062] The guidewire 110 can be used with an aspiration / suction catheter, where a vacuum source is located at the proximal end of the aspiration catheter. Aspiration is sometimes used to assist in clot retrieval, where the suction is used to remove clots lodged within the vasculature. Here, suction can be used to seal the guidewire 110 against the guide catheter 38. In one example, suction is used to seal the guidewire projection 16 against the guide catheter 38 and seal any gaps between the guidewire 110 and the guide catheter 38. Suction is then applied at the proximal end of the guide catheter 38, and the guide catheter 38 is advanced through the vasculature while continuing to seal the guidewire projection against the catheter.

[0063] In one embodiment, the distal section of the guide catheter 38 is radially reduced compared to the remainder of the guide catheter. A guidewire 110 having a protrusion 116 is advanced through the guide catheter 38, while the protrusion 116 contacts the radially reduced distal section of the guide catheter 126, sealing the gap between the guide catheter 38 and the guidewire 110. The distal tip segment 138 can be radially reduced, as shown in FIG. 7a, or the distal tip 138 can taper inward to contact the protrusion, as shown in FIG. 7b. In some embodiments, a marker band 129, as shown in FIG. 7a, can optionally be used immediately adjacent to the radially reduced region. Here, the guidewire protrusion marker band 118 aligns with the radially reduced section marker band 129 of the guide catheter 38, allowing the user to confirm proper placement of the guidewire 110 relative to the guide catheter 38. In another embodiment, the guide catheter 38 has a relatively constant diameter, and the guidewire projection 116 is sufficiently malleable so that as the user pushes and pulls the guidewire 110, the guidewire projection 116 shrinks and passes easily through the guide catheter 38.

[0064] 8, the guidewire projection 116 is wedge-shaped and has tapered distal and proximal surfaces 116a, 116b. The tapered proximal surface is approximately equal to or slightly larger than the diameter of the guide catheter 116 to eliminate any gaps between the guidewire 116 and the guide catheter 38. If the guidewire projection 116 is slightly larger than the guide catheter 38, the guidewire projection should be malleable and pushable to allow the guidewire 110 to be moved (pushed / pulled) through the guide catheter 38 without any issues.

[0065] Another embodiment, shown in FIG. 9, can utilize an intermediate rapid exchange system, where an easily deployable device bridges the gap between the guidewire and guide catheter and can move the outer periphery of the guidewire to eliminate the gap. In operation, if a conventional guidewire is used and there is a gap between the guidewire and the outer periphery of the guide catheter that becomes trapped at a vessel bifurcation, the user can move the rapid exchange device over the outer periphery of the guidewire to eliminate the gap. Alternatively, if the user is maneuvering the guidewire through a bifurcation area, the user can preemptively move the rapid exchange system over the outer periphery of the guidewire to bridge the gap between the guidewire and guide catheter, mitigating potential problems due to the ledge effect.

[0066] FIG. 9 illustrates a rapid exchange intermediate catheter 151 utilizing a core wire 144 having a proximal handle 144a that a user uses to manipulate (e.g., push and withdraw) the catheter 151. The distal portion of the core wire 144 is connected to a tubular portion 148. The tubular portion 148 has a proximal opening 146 and a distal opening 154, allowing passage of a guidewire 22. The tubular portion 148 can optionally utilize a radiopaque marker band 152. Guide catheters typically include a marker band 3 centimeters from their distal tip. Therefore, the tubular portion marker band 152 can be used to ensure accurate alignment with the distal tip of the guide catheter. The distal portion of the tubular portion 148 includes an expanded shape or enlarged region 150 that bridges the gap between the tubular portion 148 and the interior of the guide catheter 38. Region 150 is advanced to the distal tip of guide catheter 38 so as to eliminate any gap between guidewire 151 and the distal opening of guide catheter 38. In practice, if a user desires to eliminate any gap at the guide catheter distal tip between a guidewire already deployed within the guide catheter and the guide catheter, the user moves tubular portion 148 of the rapid exchange system over the outer surface of the guidewire, pushing the system over core wire 144 until the system is properly positioned so that enlarged region 150 fills the gap between the guide catheter and the guidewire.

[0067] It should be noted that the figures presented are provided as visual examples to aid in interpretation and understanding. Sizes and measurements are provided only as examples to aid in understanding and are not meant to be specifically limited to those literally depicted.

[0068] While the present invention has been described with respect to particular embodiments and applications, those skilled in the art, in light of this teaching, can generate additional embodiments and modifications within the scope of the invention without departing from the spirit of the invention as set forth in the claims. Accordingly, it should be understood that the drawings and specification of this application are provided by way of example to facilitate understanding of the invention and should not be construed to limit its scope.

Claims

1. 1. A microcatheter for use in advancing through a vessel bifurcation area, comprising: The first section and a second section distal to the first section, the second section having an outer diameter greater than the outer diameter of the first section; a distal tip distal to the second section, and an outer diameter of the distal tip being smaller than the outer diameter of the second section; The second section is configured to form an interface between the microcatheter and a guide catheter on the outer circumferential surface side to minimize an open space.

2. 10. The microcatheter of claim 1, wherein the length of the second section is between 0.5 centimeters and 3 centimeters, and the diameter of the second section is between 0.013 inches and 0.073 inches.

3. 10. The microcatheter of claim 1, wherein the second section utilizes a lubricious coating.

4. The microcatheter of claim 1, wherein the second section has two marker bands.

5. 5. The microcatheter of claim 4, wherein one of the marker bands is located at each end of the second section.

6. 10. The microcatheter of claim 1, wherein the inner diameter of the microcatheter is constant along the entire length of the microcatheter.

7. 10. The microcatheter of claim 1, wherein the distal tip has one marker band.

8. 2. The method of claim 1, wherein the outer diameter of the distal tip is equal to the outer diameter of the first section. The microcatheter shown.

9. 1. An implant delivery system configured to navigate through a vessel bifurcation area to access a treatment site, comprising: Implants and Guide catheter and a guidewire deployable through the guide catheter; a microcatheter that can be deployed on an outer peripheral surface of the guidewire via the guide catheter; and the implant that can be delivered via the microcatheter, The microcatheter comprises: The first section and a second section distal to the first section, the second section having an outer diameter greater than the outer diameter of the first section; the second section of the microcatheter is configured to form an interface between the microcatheter and the outer peripheral surface of the guide catheter to minimize open space; an outer diameter of the distal tip distal to the second section, the outer diameter of the distal tip being smaller than the outer diameter of the second section.

10. 10. The implant delivery system of claim 9, wherein the length of the second section is between 0.5 centimeters and 3 centimeters, and the diameter of the second section is between 0.013 inches and 0.073 inches.

11. 10. The implant delivery system of claim 9, wherein the second section utilizes a lubricious coating.

12. 10. The implant delivery system of claim 9, wherein the second section of the microcatheter has two marker bands.

13. 13. The implant delivery system of claim 12, wherein one of the marker bands is located at each end of the second section.

14. 10. The implant delivery system of claim 9, wherein the inner diameter of the microcatheter is constant along the entire length of the microcatheter.

15. 10. The method of claim 9, wherein the distal tip of the microcatheter has one marker band.

10. An implant delivery system as described.

16. 10. The implant delivery system of claim 9, wherein the outer diameter of the distal tip of the microcatheter is equal to the outer diameter of the first section of the microcatheter.

17. 10. The implant delivery system of claim 9, wherein the implant is a clot retrieval device.

18. 18. The implant delivery system of claim 17, wherein the clot retrieval device is a stent retriever.

19. 1. A method for delivering an implant through a vessel bifurcation region, comprising: moving a guide catheter over the outer surface of the guidewire; and advancing the microcatheter over the guidewire and through the guide catheter so that the microcatheter is positioned distal to the guide catheter; The microcatheter comprises: The first section and a second section distal to the first section, the outer diameter of the second section being greater than the outer diameter of the first section, whereby the second section is configured to form an interface between the microcatheter and the guide catheter on the outer peripheral surface side to minimize an open space; a distal tip distal to the second section, and an outer diameter of the distal tip being smaller than the outer diameter of the second section.

20. 20. The implant delivery method of claim 19, further comprising aligning the microcatheter with respect to the guide catheter so that two marker bands on the distal section of the microcatheter are located on either side of a guide catheter marker band.

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