Catheter

A catheter including a tube and a coil at least partially surrounding the tube is disclosed. The coil can include a first portion including a first material, and a second portion including a second material.

TECHNICAL FIELD

This invention relates to catheters, as well as related systems and methods.

BACKGROUND

Systems are known for delivering medical devices, such as stents, into a body lumen. Often, such systems include a proximal portion that remains outside the body during use and a distal portion that is disposed within the body during use. The proximal portion typically includes a handle that is held by an operator of the system (e.g., a physician) during use, and the distal portion can include a sheath surrounding a catheter with a stent positioned therebetween. Generally, the operator of the system positions the distal portion within the lumen at a desired location (e.g., so that the stent is adjacent an occlusion). The operator can then retract the sheath to allow the stent to engage the occlusion/lumen wall. Thereafter, the operator removes the distal portion of the system from the lumen.

SUMMARY

In general, the invention relates to catheters, as well as related systems and methods. The catheters can be used, for example, in implantable medical endoprosthesis delivery systems (e.g., stent delivery systems). The systems can be used, for example, to deliver a medical endoprosthesis (e.g., a stent) at a desired location within a lumen of a subject (e.g., an artery of a human).

The catheters generally include a tube and a coil that at least partially surrounds the tube. In some embodiments, the coil can include a first portion disposed inwardly of a second portion, where the first and second portions are made of different materials. For example, the first portion of the coil can be in the form of a wire (e.g., a wire formed of a metal or alloy), and the second portion of the coil can be a polymer (e.g., a thermoplastic) coated on the wire. In certain embodiments, the tube and coil can be at least partially surrounded by a sheath (e.g., a sheath that is heat shrunk to the exposed surfaces of the tube and coil).

The catheters can be sufficiently flexible for use in implantable medical endoprosthesis delivery systems while also having a relatively high compression resistance. This can, for example, allow the catheters to undergo little or no compression or buckling during deployment of a medical endoprosthesis (e.g., stent), which can enhance the precision of placement of the medical endoprosthesis (e.g., stent) during deployment.

Alternatively or additionally, the catheters can be designed to allow good fluid flow between the catheter and a surrounding sheath, which can aid in delivery of the system to a desired site within a subject (e.g., a human) and/or deployment of the medical endoprosthesis (e.g., stent) at a desired site (e.g., an artery of a human).

Other features and advantages of the invention will be apparent from the description, drawings and claims.

DETAILED DESCRIPTION

FIGS. 1-3show an implantable medical endoprosthesis delivery system10that includes a catheter12, a sheath14surrounding catheter12, and a stent32positioned between catheter12and sheath14. The delivery system10includes a distal end16dimensioned for insertion into a body lumen (e.g., an artery of a human) and a proximal end18that resides outside the body of a subject, and that contains at least one port50and lumens for manipulation by a physician. A guide wire20with a blunted end22is inserted into a body lumen24by, for example, making an incision in the femoral artery, and directing guide wire20to a constricted site26of lumen24(e.g., an artery constricted with plaque) using, for example, fluoroscopy as a position aid. After guide wire20has reached constricted site26of body lumen24, catheter12, stent32and sheath14are placed over the proximal end of guide wire20. Catheter12, stent32and sheath14are moved distally over guide wire20and positioned within lumen24so that stent32is adjacent constricted site26of lumen24. Sheath14is moved proximally, allowing stent32to expand and engage constricted site26. Sheath14, catheter12and guide wire20are removed from body lumen24, leaving stent32engaged with constricted site26.

As shown inFIGS. 4-6, catheter12includes a tube62surrounded by a coil64. Catheter12also includes a coating72that surrounds tube62and coil64. Catheter12is dimensioned so that a space, S, is present between catheter12and sheath14(seeFIG. 4, area C). Without wishing to be bound by theory, it is believed that with this configuration catheter12can exhibit enhanced compression resistance with little or no buckling of catheter12(e.g., as sheath14is retracted proximally). It is also believed that this configuration also allows for appropriate fluid flow between catheter12and sheath14.

Outer portion66can be, for example, a polymeric material, such as a plastic (e.g., a thermoplastic). Examples of polymeric materials include polyamides, polyurethanes, styrenic block copolymers, nylons, thermoplastic polyester elastomers (e.g., Hytrel®), copolyester elastomers (e.g., Arnitel® copolyester elastomers), polyether-block co-polyamide polymers (e.g., PEBAX®) and HDPEs. In some embodiments, outer portion66is integral with the outer surface of tube62. This can, for example, assist in maintaining the position of coil64constant with respect to tube62.

In some embodiments, coil64is a helical coil with a pitch, P, (seeFIG. 5A) between adjacent windings of, for example, from at least about 0.005 inch (e.g., at least about 0.01 inch, at least about 0.05 inch) and/or at most about 0.1 inch (e.g., at most about 0.075 inch, at most about 0.06 inch). In certain embodiments, the pitch P of coil64is from about 0.005 inch to about 0.1 (e.g., from about 0.01 inch to about 0.06 inch, from about 0.05 inch to about 0.06 inch). In some embodiments, coil64is circular in cross-section with a diameter, D, (seeFIG. 5B) of at least about 0.002 inch (e.g., at least about 0.004 inch) and/or at most about 0.01 (e.g., at most about 0.005 inch). For example, in certain embodiments, the diameter, D, of coil64can be from about 0.002 inch to about 0.1 inch (e.g., from about 0.004 inch to about 0.006 inch, about 0.005 inch).

In general, coating72is made of a material that can be bonded to the exposed outer surfaces of tube62and coil64. Examples of such materials include heat shrink materials and polymeric materials such as polyether-block co-polyamide polymers (e.g., PEBAX®) and nylons. Examples of heat shrink materials include cross-linked polyethylene, polyester (e.g., PET) heat shrink, fluorinated ethylene (FEP) heat shrink, polytetrafluoroethylene (PTFE) heat shrink. In some embodiments, coating72includes an additive (e.g., a fluoropolymer, a silicone, an ultrahigh molecular weight polyethylene, an oil, or blends thereof) to assist in the movement of catheter12with respect to sheath14and stent32. In certain embodiments, the thickness, T, of coating72(seeFIG. 5B) is at least about 0.001 inch (e.g., at least about 0.002 inch) and/or at most about 0.01 inch (e.g., at most about 0.008 inch). In some embodiments, the thickness, T, of coating72is from about 0.001 inch to about 0.01 inch (e.g., from about 0.002 inch to about 0.008 inch, about 0.006 inch).

Stent32is typically formed of a shape memory alloy. Examples of shape memory alloys include those discussed above with respect to inner portion68of coil64.

Typically, sheath14is made of a polymeric material. Examples of polymeric materials include those noted above with respect to tube62. In some embodiments, sheath14includes an additive (e.g., a fluoropolymer, a silicone, an ultrahigh molecular weight polyethylene, an oil, or blends thereof) to assist in the movement of sheath14with respect to catheter12and stent32.

FIG. 4shows that system10can further include a bumper70that is integral with tube62, and a tip61that is integral with tube62. Bumper70can reduce the possibility of stent32moving proximally as sheath14is retracted proximally, and tip61can assist in positioning of system10within body lumen26(e.g., as system10is moved distally over guide wire20within body lumen24). In some embodiments, bumper70is formed of a polymeric material, such as a polyether-block co-polyamide polymer (e.g., PEBAX®) or a thermoplastic polyurethane elastomer (e.g., Pellethane™). In certain embodiments, bumper70is made of a metal or an alloy, such as, for example, stainless steel, Nitinol and/or platinum. Tip61is typically formed of a relatively soft polymeric material.

In general, catheter12can be prepared as desired. In some embodiments, catheter12can be prepared as follows.

A monofilament having a transverse cross-section similar to that of coil64is prepared.FIG. 7illustrates an embodiment of a pultrusion process for a making a monofilament100. A spool112of a metallic filament (e.g., stainless steel wire)114is pulled through a fluid polymeric material (e.g., molten thermoplastic)116that is pumped onto filament114by extruder118as filament114passes through a die120with an aperture122. After exiting die120, monofilament100is collected on a spool101. Pultrusion processes are disclosed, for example, in U.S. Pat. Nos. 4,530,855, 4,861,621, 4,862,922, 5,607,531 and 5,614,139. Equipment for performing pultrusion processes is commercially available from, for example, Entec Composite Machines, Salt Lake City, Utah (USA) and Pultrex, Essex (UK).

Monofilament100is formed into a coil.FIG. 8shows an embodiment of a process for forming monofilament100into a coil by winding monofilament100around a mandrel102as mandrel102is rotated by a motor132. Monofilament100is supplied to mandrel102via a main tension pulley134and a cantilevered pulley136. Generally, mandrel102is several inches (e.g., about two inches) longer than the desired coil length. Filament winding processes are disclosed, for example, in U.S. Pat. Nos. 5,335,167 and 5,601,599. Filament winding equipment is commercially available from, for example, Pultrex, Essex (UK). Wound monofilament100is removed from mandrel102to provide coil64(seeFIG. 9).

Tube62is placed around a support member, then coil64is placed around tube62, and wound filament100is made integral with tube62, thereby providing tube62surrounded by coil64(see discussion above).FIG. 10shows tube62disposed around a support member150. Support member150reduces the possibility of tube62being deformed during subsequent processing. After being positioned around tube62, coil64can be made integral with tube62by exposure to energy (e.g., heat, UV, IR). In some embodiments, outer material66of coil64is a thermoplastic material, and coil64can be made integral with tube62by heating outer material66with a heat gun so that outer material66is welded to tube62.

A coating material is placed around tube62and coil64, and the coating material is processed to form coating72(see discussion above).FIG. 11shows an embodiment in which a heat shrink tubing152is disposed around tube62and coil64. Tubing152is then exposed to radiation (e.g., heat, UV, IR) to collapse tubing152and adhere it to the exposed outer surfaces of tube62and coil64, thereby forming coating72.

While certain embodiments have been described, other embodiments are possible.

As an example, while systems including a self-expanding stent have been described, other types of implantable medical endoprostheses can be used in the systems. For example, the implantable medical endoprosthesis can be a balloon-expandable implantable medical endoprostheses (e.g., a balloon-expandable stent). In such systems, inner catheter12would typically include an expandable balloon in the region around which the implantable medical endoprostheses is exposed during delivery. Additional examples of implantable medical endoprostheses include stent-grafts and filters (e.g., arterial filters, venus filters).

As another example, while embodiments of catheter12have been described in which catheter12includes coating72, in some embodiments catheter12does not include coating72.

As an additional example, while embodiments of catheter12have been described in which coil64is formed of two different (inner and outer) layers, in certain embodiments coil64may be formed of a single portion, or coil64may be formed of more than two portions (e.g., three layers, four layers, five layers, six layers, seven layers, eight layers, nine layers,10layers). Optionally, the portions can be in the shape of layers.

As a further example, while embodiments have been described in which coil64has a circular transverse cross-section, in some embodiments coil64can have a noncircular transverse cross-section (e.g., half moon shaped transverse cross-section, rectangular transverse cross-section, hexagonal transverse cross-section, pentagonal transverse cross-section, octagonal transverse cross-section). This can be achieved, for example, by using a correspondingly shaped inner portion (e.g., a correspondingly shaped wire). As an example, in embodiments in which inner portion68has a rectangular transverse cross-section, the width of the transverse cross-section of inner portion68can be, for example, at least about 0.001 inch (e.g., at least about 0.004 inch) and/or at most about 0.01 inch (e.g., at most about 0.008 inch), and the length of the transverse cross-section of inner portion68can be, for example, at least about 0.001 inch (e.g., at least about 0.004 inch) and/or at most about 0.05 inch (e.g., at most about 0.03 inch). As another example, in embodiments in which inner portion68has a half-moon transverse cross-section, the transverse cross-section of inner portion68can be at least about 0.001 inch (e.g., at least about 0.004 inch) and/or at most about 0.03 inch (e.g., at most about 0.01 inch), and the orthogonal dimension of the transverse cross-section of inner portion68can be at least about 0.001 inch (e.g., at least about 0.003 inch) and/or at most about 0.01 inch (e.g., at most about 0.008 inch).

As another example, in some embodiments, coating72is created by a pultrusion process.

As an additional example, while embodiments have been described in which there is a space between catheter12and sheath14, in some embodiments catheter12and sheath14are dimensioned so that they are in contact. In such embodiments, fluid flow between catheter12and sheath14can be achieved, for example, along coil64.

As a further example, in some embodiments wire114is drawn through a resin bath rather than die120. In certain embodiments (e.g., to toughen the outer portion of the monofilament), the resin (e.g., a thermoset) can be cured by heat. Optionally, additional materials (e.g., pigments, curing accelerators, fillers, release agents) can be added to the outer portion of monofilament100.

As another example, while embodiments have been described in which coil64has a constant pitch, in certain embodiments, the pitch of coil64can vary, or coil64can include regions in which the pitch varies. For example, coil64can have a first region in which coil64has a constant pitch, and coil64can have a second region in which coil64has a constant pitch that is different from the pitch in the first region of coil64.

As an additional example, in some embodiments coil64surrounds only a portion of tube62.

As a further example, multiple coils can surround tube62. For example, each coil can surround a different region of tube62.

Other embodiments are in the claims.