Patent Application
20060264905
The present invention relates to improved catheters having atraumatic distal conformations and surface discontinuities that ease guidance through vessels or other lumens or cavities and prevent damage to vessel walls, as well as improving operation in connection with associated devices and procedures.
Catheters are flexible tubes used for navigating internal body vessels and lumens and guiding devices within the body, such as in the vasculature, spinal column, fallopian tubes, bile ducts, and the like, and are often used in connection with minimally invasive diagnostic or surgical techniques. Catheters may be used for medical procedures to examine, diagnose and treat internal conditions while positioned at a specific location within the body that is otherwise inaccessible. An intravascular catheter is generally inserted and advanced through a valved introducer fitting into a blood vessel near the surface of the body, such as the femoral artery, and is guided through the vasculature to a desired location. Catheters are used for coronary vascular and cardiac-related interventional operations, as well as neurovascular interventions, peripheral vascular, renal, and other types of intravascular interventions. Medical devices and instruments may be guided, through the catheter, to the desired site and operated.
Guiding catheters are generally the catheters through which various interventional devices and instruments are supported and guided during passage to a desired internal location. Guide catheters are sold in a variety of pre-formed sizes and shapes, customized for desired procedures. Microcatheters are generally smaller diameter catheters used for delivery of agents, devices or instruments through small diameter vessels in neurovascular interventions. Therapeutic devices and agents such as embolization coils, pharmaceutical agents, and embolic materials are delivered to a neurovascular site through microcatheters, for example. Both flow-guided and wire-guided microcatheters are used for interventional navigation. Catheters intended for use in small, delicate or tortuous vessels often have soft, shaped distal tips intended to facilitate navigation to and retention in particular target sites.
Intravascular catheters must be flexible enough to navigate through the sometimes tortuous vasculature without damaging tissue, yet stiff enough to provide “pushability” through the vasculature and support for internally guided medical devices, fluids, and the like and must be kink-resistant. Guide catheters may have a composite construction that provides greater stiffness and support in proximal areas with more softness and flexibility in distal areas. The inner lumens of guide catheters may be coated with a lubricious coating or constructed from a lubricious material such as PTFE (Teflon). The outer catheter surface may be provided with a hydrophilic coating to enhance lubricity and facilitate passage through vessels during navigation of the catheter. Microcatheters are generally smaller diameter, have a low distal profile and are soft and flexible, with a smooth inner lumen surface.
One of the problems encountered with intravascular catheters is that contact of the distal catheter tip with a vessel wall during navigation to a desired site or with a site during an intervention may injure the vascular wall or tissue at the site. Contact between a guiding catheter and a vessel wall, for example, may produce vessel dissection and/or vasospasm, which can cause complications such as clot formation or thrombosis during an intravascular procedure. Catheters having soft and/or flexible distal portions are less prone to damage vessel walls and tissue, but tissue damage and vasospasm during catheter navigation and placement remain problematic.
Yet another challenge encountered with intravascular catheters is providing quick and reliable passage of instruments and devices through the length of the catheter for delivery to a desired internal site. Inner walls of delivery catheters may comprise a lubricious layer or coating to facilitate sliding of an accessory device or instrument within the lumen, but such a coating may not provide sufficient lubricity to translate a device through the length of the catheter lumen, particularly if the path involves tortuous passages or the lumen is narrow compared to the dimensions of the accessory device or instrument.
In one aspect, the present invention relates to catheters having a distal tip conformation that is tapered and substantially atraumatic. The distal catheter portion has a lumen that is generally axially aligned with and forms an extension of the proximal and middle section catheter lumens. In one embodiment, proximal and middle portions of a catheter have substantially cylindrical inner and outer cross-sectional conformations, while a distal portion of the catheter has an outer surface having a substantially non-cylindrical cross-sectional configuration. The distal portion of the catheter may also be tapered along a curved or linear profile and have a reduced dimension outer perimeter compared to the outer perimeter dimension(s) of the remainder of the catheter.
According to one embodiment, the outer surface cross-sectional configuration of the distal portion of the catheter is generally triangular and has arced corners separated by generally linear or slightly curved side walls. In another exemplary embodiment, the distal portion of the catheter has a generally pentagonal or hexagonal cross-sectional profile with arced corners separated by generally linear or slightly curved side walls. The material forming the distal portion of the catheter may have different, generally more flexible and resilient properties, than those of the material forming the remainder of the catheter. The arced corners may have different flexibility or elasticity properties than those of the side walls, and may have a different cross-sectional thickness than that of the side walls.
The inner surface cross-sectional configuration of the distal portion of the catheter may substantially match the configuration of the outer surface, or it may have a different configuration. In one embodiment, for example, the cross-sectional configuration of the inner surface of the distal portion forming the lumen may be generally cylindrical or oval, while the outer distal portion surface may be generally triangular. The catheter lumen may have constant diameter along the length of the catheter, including the distal portion, or the lumen at the distal catheter portion may have a smaller diameter compared to that of the proximal and/or middle catheter portions. The terminal orthogonal surface of the distal portion of the catheter is preferably chamfered or rounded or otherwise contoured to further render the distal tip atraumatic and to minimize the incidence of damage to vessel walls or other lumen surfaces.
The atraumatic catheter distal portion may be constructed integrally with the remainder of the catheter, or the atraumatic distal catheter portion may be constructed separately and installed or mounted on the remainder of the catheter. The catheter distal portion may have enhanced flexibility or elasticity compared to the flexibility or elasticity of the remainder of the catheter. The distal catheter portion may have a generally linear, angled or curved axial alignment.
According to another aspect of the present invention, inner and/or outer catheter surfaces may have a three-dimensional surface conformation. In one embodiment, for example, catheter surfaces, and particularly inner catheter surfaces forming lumens, may be dimpled or grooved or provided with other types of surface discontinuities to reduce friction and enhance the slidability of and passage through the lumen of instruments, accessory devices, and the like. The dimpled and/or grooved surface discontinuities may be provided in a regular or irregular pattern and may be provided in connection with and in addition to lubricious coatings and surfaces. In another embodiment, outer catheter surfaces may additionally or alternatively be dimpled or grooved or provided with other types of surface discontinuities.
Numerous catheter materials and constructions are known, and catheters of the present invention may be constructed using any materials, composite arrangements and conformations and construction techniques known in the art. Many catheters, for example, have a multi-layer construction and may be reinforced in sections or along their length, and may have different properties and dimensions along their length. Inner and/or outer surfaces may be provided with coatings or constructed from materials that enhance lubricity. Suitable coatings and materials are well known in the art. Radio-opaque markers may be incorporated in the catheters to allow for visualization and precise positioning, as is known in the art.
Various aspects of applicants' claimed inventions are illustrated schematically in the accompanying drawings, which are intended for illustrative purposes only and are not drawn to scale.
Catheters of the present invention comprise generally tubular structures having a substantially continuous side wall forming a lumen and may be used for a variety of purposes. Such catheters may be employed, for example, as guide catheters or delivery catheters or microcatheters for delivery of accessory devices, instruments, pharmaceuticals or other agents, or the like, to a target site within the body that is generally accessible through the vasculature or a body opening or lumen. Catheters of the present invention thus include guide and delivery catheters used for any intravascular purpose and microcatheters designed for neurovascular interventions. Catheters of the present invention may also include sheaths and other types of tubular structures used for delivery of devices, instruments, or the like to target sites within the body.
As used herein, the term “proximal” refers to a direction toward an operator and the site of catheter introduction into a subject along the path of the catheter system, and “distal” refers to the direction away from the operator and introduction site along the path of the catheter system toward a terminal end of the catheter assembly.
Many different catheter types and constructions are known in the art and catheters of the present invention may have a variety of constructions, properties, and the like. Catheters may, for example, comprise a multi-layer construction in which flexible tubing is reinforced with stiffer materials such as helical coils and braided materials to provide different stiffness properties along the length of the catheter. Coatings may be provided on the inner or outer surfaces of catheters to improve lubricity. Hydrophilic coatings are often provided on exterior surfaces to facility guidance through tortuous vasculature. Liners comprising lubricious materials such as fluoropolymer resins, films and coatings, such as TEFLON® PTFE and similar materials may be provided on inner catheter surfaces to enhance passage of accessory devices and systems through the catheter.
Catheters may also have different cross-sectional dimensions and/or thicknesses and/or flexibilities along their lengths. In general, catheters have a larger cross-sectional outer dimension and have thicker, less flexible walls in proximal sections and a smaller cross-sectional outer dimension with thinner, more flexible walls in distal sections. The length of a guide catheter may be up to 100 cm or more, and the outer lumen diameter (French size) of a guide catheter may range from 4-10 F. The length of a microcatheter for use, for example, in neurovascular applications, may be up to 170-200 cm, and the outer lumen diameter of a microcatheter may range from about 1.5-3.5 F. Microcatheters often incorporate a flexible distal tip for a length of from about 5 cm to 50 cm from the terminal distal end that is soft, perhaps shapeable, and has one or more radiopaque markers for relative positioning by the physician. The tip configuration may be preformed or formable in a variety of configurations, including linear and curved, as well as angled. Catheters of the present invention may incorporate any of these features. U.S. Pat. Nos. 6,672,338, 6,152,944, 6,824,553, 6,863,678, 6,740,073, 6,626,889 and 6,679,836 are incorporated by reference herein in their entireties and disclose exemplary types of catheters and catheter constructions, any of which may be used in connection with catheters of the present invention. Numerous other catheter types and constructions are known in the art and may be used in combination with the novel catheter features described herein.
Catheters of the present invention comprise an elongate tubular member defining an inner lumen extending from a proximal end to a distal end of the tubular member. One aspect of catheters of the present invention is directed to the distal portion of the catheter and is illustrated schematically in
Tapered tip section 24 terminates in a distal surface 34 and comprises a tapered side wall 36 that may be angled or curved relative to the longitudinal axis of tubular section 22. In the embodiment shown in
In the catheter embodiments illustrated in
In one embodiment, the cross-sectional configuration of the outer perimeter of tapered tip section 24 is generally circular and is substantially similar to, though of smaller diameter than, the cross-sectional configuration of tubular section 22. In alternative embodiments, the cross-sectional configuration of the outer perimeter of tapered tip section 24 in its distal region is different from the cross-sectional configuration of distal cylindrical profile 30. In one embodiment, illustrated in
Catheter tapered tip section 24 thus tapers in a distal direction to provide an outer surface having a smaller perimeter at a distal section than at a proximal section and, in some embodiments, a different cross-sectional profile at a distal section than at a proximal section. In the embodiment illustrated in
Tapered tip section 24 is preferably flexible and may have a relatively high degree of elasticity. For catheter applications in which devices or instruments having a profile larger than that of the inner diameter of catheter tip section 24 are being introduced and/or withdrawn, for example, catheter tip section 24 is preferably elastic and deformable to provide passage of such devices and instruments. In one embodiment, arced corners C1, C2 and C3 may have different flexibility or elasticity properties than side walls S1, S2 and S3 and arced corners C1, C2 and C3 may have different wall thicknesses than side walls S1, S2 and S3.
In another aspect, catheters of the present invention incorporate inner and/or outer catheter surfaces having a three-dimensional surface conformation. In one embodiment of a neurovascular microcatheter, for example, an inner catheter surface forming a lumen may be dimpled or grooved or provided with other types of surface discontinuities to reduce friction and enhance the slidability of and passage through the lumen of instruments, accessory devices, and the like. The outer surface of a catheter may also be provided with surface discontinuities to facilitate passage of the catheter through vessels and tortuous passageways.
Discontinuities 46 and 56 may be provided on inner and outer catheter walls, respectively, in areas where contact of the lumen wall with accessory devices or instruments reduces friction and enhances slidability. In preferred embodiments, the maximum depth of discontinuities 46 and 56 is relatively shallow and is less than about 6μ, while the maximum dimension of discontinuities 46 and 56, which is the diameter in the embodiment shown, is less than about 10μ and, more preferably, less than about 8μ. The pattern of surface discontinuities is preferably regular, though irregular patterns may be implemented for specific applications. The density and/or pattern and or configuration of discontinuities may vary along the length of a catheter or catheter section, with higher density discontinuities in narrower catheter sections to improve sliding of devices and instruments in the catheter lumen and/or sliding of the catheter outer surface within a vessel.
In yet another embodiment, an inner or outer catheter wall may be provided with surface discontinuities in the form of grooves that are generally longitudinal or curved or provided in a helical or spiral configuration.
The grooved inner lumen wall of the catheter may alternatively or additionally comprise lands and grooves in a pattern that facilitates both passage and rotation of an accessory device or instrument through the lumen. These surface discontinuities may be provided in any region of a catheter and may, in some embodiments, be provided on the inner lumen wall of a distal tapered section of a catheter.
The lands and grooves in this embodiment may be slightly curved or generally rectilinear, having generally flat or curved side walls. This pattern of lands and grooves is similar to rifling patterns used in rifle barrels to facilitate the transit and rotation of bullets or other projectiles. In a similar fashion, broach or button rifling techniques may be used to form surface discontinuities in connection with catheter or catheter sections of the present invention. Conventional rifling patterns that are suitable for use in catheters of the present invention include 4/right, 5/right, 6/right, 6/left, 8/right and 16/right.
While in the foregoing specification this invention has been described in relation to certain preferred embodiments thereof, and many details have been set forth for purposes of illustration, it will be apparent to those skilled in the art that the invention is susceptible to various changes and modification as well as additional embodiments and that certain of the details described herein may be varied considerably without departing from the basic spirit and scope of the invention.
All of the patent references and publications cited in this specification are incorporated by reference herein in their entireties.
This application claims priority under 35 U.S.C. 119(e) to U.S. Patent Application No. 60/676,925, filed May 2, 2005.
| Number | Date | Country | |
|---|---|---|---|
| 60676925 | May 2005 | US |
