Patent Application
20100030192
This disclosure relates to catheter systems and related methods of operating and manufacturing catheter systems. Preferred arrangements also relate to catheter shaft bond arrangement and related methods.
Catheters are used with stents and balloon inflatable structures to treat conditions such as strictures, stenoses, and narrowing in various parts of the body. Various catheter designs have been developed for the dilatation of stenoses and to deliver and deploy stents at treatment sites within the body.
Stents are typically intraluminally placed by a catheter within a vein, artery, or other tubular shaped body organ for treating conditions such as, for example, occlusions, stenoses, aneurysms, dissection, or weakened, diseased, or abnormally dilated vessel or vessel wall, by expanding the vessel or by reinforcing the vessel wall. Stents can improve angioplasty results by preventing elastic recoil and remodeling of the vessel wall and treating dissections in blood vessel walls caused by balloon angioplasty of coronary arteries.
While conventional stent technology is relatively well developed, stent technologies related to treatment of the region of a vessel bifurcation are still being developed. One challenge related to treatment of a vessel bifurcation involves alignment of the stent relative to the vessel branch of the vessel bifurcation. Maintaining proper relative positioning of features of the catheter assembly used to deliver and deploy the stent at the vessel bifurcation can be an important aspect of achieving the desired stent alignment.
The illustrated examples disclosed herein relate generally to catheter assemblies and related methods for maintaining relative positioning of various catheter shafts of a catheter assembly. One application that can benefit from the principles disclosed herein is treatment of vessel bifurcations. A vessel bifurcation can be defined as an area of a vessel in which at least one branch vessel diverts or branches away from a main vessel. An example catheter assembly configured for treatment of a vessel bifurcation carries a stent to the bifurcation treatment site. Some catheter assemblies include features that orient the stent relative to the branch vessel of the vessel bifurcation and maintain that orientation during treatment of the vessel bifurcation.
An example catheter assembly includes a main catheter branch and a side catheter branch. Typically, a main balloon is positioned at a distal end portion of the main catheter shaft. The main balloon extends from a distal open end to a proximal open end of the stent. The side catheter branch extends through the proximal open end of the stent and out of a side opening of the stent. A distal end portion of the side catheter branch extends into a branch vessel at the vessel bifurcation and is used to help orient the side opening of the stent relative to the branch vessel. Maintaining a fixed radial and axial position of the side catheter branch relative to the main catheter branch along a length of the side catheter branch can help maintain proper alignment of the stent side opening relative to the branch vessel. The relative position of the side catheter branch to the main catheter branch can be maintained using, for example, various bonding and other securing techniques.
There is no requirement that an arrangement include all features characterized herein to obtain some advantage according to this disclosure.
This disclosure relates to catheter assemblies and related methods for maintaining relative positioning of various catheter shafts of a catheter assembly. The disclosed catheter assemblies and related methods include a main catheter shaft and a branch catheter shaft. A main balloon and a stent are typically positioned at a distal end portion of the main catheter shaft. The branch catheter shaft can be used to help orient the stent relative to a branch vessel at a vessel bifurcation. Maintaining a fixed axial and radial position of the branch catheter shaft relative to the main catheter branch can provide improved consistency in orienting the stent relative to the branch vessel prior to and during inflation of the balloon to expand the stent. The branch catheter shaft can be secured to the main catheter shaft using any of a variety of techniques such as, for example, heat bonding and adhesives.
The use of adhesives to secure the main and branch catheter shafts together can have certain disadvantages in performance and manufacturing. Adhesives are susceptible to the formation of voids that can cause failure of the bond joint. It can be difficult to inspect for voids and other problems with adhesive bonds during the manufacturing process. Making an adhesive joint can also be time consuming and require manufacturing of batches of product due to the time and space required for applying and curing the adhesive.
Securing catheter shafts together using heat bonding techniques can have advantages over adhesives. When securing together two polymer-based materials, such as those materials typically used for catheter shafts (see below), with a heat bond, cross-linking of the polymer chains of the two materials creates a physical bond. Heat bonds are typical stronger and more durable than a bond created using adhesives because of the cross-linking of the polymer chains in a heat bond verses bonding of the adhesive to each of the materials in an adhesive bond.
Further, a heat bond can be made relatively quickly using any one of several heat sources. Some example heat sources include a hot jaw, carbon dioxide lasers, and diode lasers. Different types of heat sources can dictate the additional features and steps required to create the heat bond. For example, using a hot jaw to create a heat bond can be accomplished by heat bonding a bond member to both catheter shafts. A heat sleeve is typically used to hold the bond member in place while heat is applied by the hot jaw.
Creating a heat bond using a diode laser can be simpler in that the diode laser merely heats one or the other of the catheter shafts at the bond location to create the heat bond without the use of an added bond member or heat sleeve. However, because a heat bond created by a diode laser does not use added material from a bond member, extra care must be taken not to weaken the catheter shafts or provide a bond that has low tensile strength. Further details related to a hot jaw and laser heat sources (e.g., a diode laser heat source) are provided in the description below.
The main catheter branch 20 includes a main balloon 22, a side inflation member 24, a side balloon 26 positioned at a location along a length of the side inflation lumen 24, and a stent 28. The stent 28 includes a side opening 30 located at a position between distal and proximal open ends of the stent 28. A distal end portion of the side catheter branch 18 extends through the proximal open end of the stent 28 and out of the side opening 30. The main and side balloons 22, 26 maintain the deflated configuration shown in
Maintaining a fixed axial and radial position of the side catheter branch 18 relative to the main catheter shaft 16 can help maintain the radial and axial position of the stent side opening 30 relative to the branch vessel 39 prior to and during inflation of the main and side balloons 22, 26 to expand the stent 28. At least one shaft bond arrangement is provided proximal of the main catheter branch 20 to help fix the axial and radial position of the side catheter branch 18 relative to the main catheter shaft 16.
The shaft bond arrangements 32, 34 and other shaft bond arrangements disclosed hereinafter are provided in order to achieve at least some of the following objectives. Preferably, the shaft bond arrangement provides a reliable connection between the side catheter branch 18 and main catheter shaft 16 that will not fail during use of the catheter assembly. The shaft bond arrangement preferably does not significantly increase the maximum outer profile of the catheter assembly as compared to the axially adjacent portions of the main and side catheter branches 16, 18 that do not include the shaft bond arrangement. Further, the shaft bond arrangement preferably does not significantly increase or alter the stiffness of the main and side catheter branches 16, 18 upon application of exterior applied forces such as bending and torsional forces. As will be discussed further below, the shaft bond arrangement can be provided in longitudinally adjacent arranged segments that help minimize increases in stiffness resulting from the shaft bond arrangement. The shaft bond arrangements preferably also do not alter the dimensions of the interior lumens defined by each of the main and side catheter branches 16, 18. These and other advantages and objectives are met and described in further detail in the description hereinafter.
An example shaft bond arrangement 100 is shown and described with reference to
The heat sleeve 144 can be used to retain the first and second bonding segments 140, 142 in engagement with each other prior to and during application of heat via a heat source. The heat sleeve 144 has a length L2 that is typically greater than the length L1. The heat sleeve 144 typically includes a size and a material composition that provides radially inward shrinking of the heat sleeve 144 when heated. Shrinking of the heat sleeve 144 applies a radially inward directed constricting force upon the first and second bonding segments 140, 142. The application of a constricting force upon the first and second bonding segments 140, 142 when a source of heat is applied to the bonding segments 140, 142 can help reduce the amount of time required to complete the heat bond and increase the integrity of the resulting heat bond. An example heat shrink material is RayChem brand material made by Tyco Electronics of Menlo Park, Calif.
The use of bonding segments 140, 142 that completely encapsulate an outer circumference of the main and branch catheter shafts 116, 118 can have certain advantages. One such advantage is that the catheter shafts 16, 18 are protected by the bonding segments from being overheated to a point where the catheter shafts themselves begin to reach a melting point. If the catheter shafts 16, 18 were heated to a melting point, the structural integrity, shape, and other characteristics of the catheter shafts 16, 18 could be affected adversely. The shape and size of the bonding segments 140, 142 also provide that there is sufficient material in the space between the catheter shafts 16, 18 to create a reliable bond between the catheter shafts 16, 18 (e.g., see the final molded bond 150 shown in
The heat sleeve 144 comprises a material that does not bond to the bonding segments 140, 142 or the catheter shafts 116, 118. Typically, the heat sleeve 144 shrinks in size (e.g., length and internal volume) upon application of heat on an exterior surface of the heat sleeve 144. Typically, the heat sleeve 144 is removed after the molded bond 150 is cured as shown in
The following is an example method of creating a shaft bond arrangement in accordance with the features described above with reference to
While specific materials, shapes and sizes of features, and amounts of time have been given in this example, variations on these aspects of the method are possible to provide the same or similar results of providing the desired heat bond.
Another example bond arrangement 200 is now described with reference to
The bonding extrusion 240 defines a main shaft bore 242 sized to receive the main catheter shaft 116, and a branch shaft bore 244 sized to receive the branch catheter shaft 118. The bonding extrusion 240 has an outer circumference and cross-sectional shape of substantially the same size as the molded bond 250 (see
As shown in
Use of the bonding extrusion 240 can have certain advantages as compared to, for example, the separate first and second bonding segments 140, 142 of the bond arrangement 100 described above. The bonding extrusion 240 can be properly positioned along both of the main and branch catheter shafts 116, 118 simultaneously. Any adjustments to the axial position of the bonding extrusion relative to the catheter shafts 116, 118 can be made easily for both of the catheter shafts 116, 118. Further, the bonding extrusion 240 is pre-shaped with a cross-sectional shape that closely matches the desired cross-sectional shape of the molded bond 250 after the bonding occurs. The bonding extrusion 240 has a cross-sectional shape that places a minimum amount of bonding material between and surrounding each of the main and branch catheter shafts 116, 118 such that the resulting molded bond 250 provides the desired bonding strength and structural integrity to resist failure, but does not unnecessarily increase the thickness of the bond arrangement 200.
The bonding extrusion 240 can be formed using different techniques such as, for example, extruding, injection molding, and casting. The bonding extrusion 240 can comprise any of a variety of polymeric or other materials that can bond with the catheter shafts 116, 118 upon application of heat.
An example method of using the shaft fit extrusion bond arrangement 200 in a process of constructing a catheter assembly is described:
While a hot jaw bonder and other specific features and conditions are described in this example method, other heat sources, shapes and sizes and other conditions can be provided to result in a similar outcome using a bonding extrusion such as member 240 described above.
Another example bond arrangement 300 is now described with reference to
The use of bonding beads 340, 342 as the bonding material in the bond arrangement 300 can have advantages compared to, for example, the bonding segments 140, 142 and the bonding extrusion 240 described above. The bonding beads 340, 342 can provide a substantially smaller amount of bonding material as compared to the bonding segments 140, 142 and the bonding extrusion 240 described above. A reduction in the amount of total bonding material used in the bond arrangement can reduce the overall stiffness created as a result the heat bonding process (see molded bond 350 in
Another advantage of the bonding arrangement 300 relates to the heat sources used to create flow of the bonding beads 340, 342. When using a hot jaw, for example, the hot jaw can be configured to contact only the beads 340, 342 while having limited contact or no contact with a limited portion of each of the main and branch catheter shafts 116, 118. This focused application of heat reduces the possibility of creating overheating and other undesired changes to the main and branch catheter shafts 116, 118.
An example method of bonding using the bead reflow bond arrangement 300 is now described:
While a specific heat source, and other features and variables have been specified in the above example, other applications can include different heat sources, features and characteristics of the components used to provide the same or similar type bead reflow bond arrangement.
Many different types of heat sources can be used to create the flow of material needed to create a heat generated bond between the main and branch catheter shafts for the bond arrangements described above. A hot jaw bonder has been described in the examples discussed above with reference to
Another heat source that can be advantageous for use in the bond arrangements disclosed herein is a carbon dioxide laser. A carbon dioxide laser can have advantages as compared to the other example heat sources described herein.
A further heat source that can have particular advantages for use with the bond arrangements disclosed herein is a diode laser. Generally, in laser welding of thermoplastics, such as those polymer materials commonly used in catheter shafts, is sometimes referred to as laser transmission welding or IR welding, in which transparent and absorbing polymer parts are bonded together. The laser beam penetrates the transparent polymer and is converted to heat in the colored/absorbing polymer. Since both of the polymer parts are pressed together during the welding process, heat is conducted from the colored/absorbing polymer to the transparent polymer, allowing both materials to flow and create a heat generated bond. Internal joining pressure is also generated through local warming and thermal expansion. The internal and external joining pressures ensure strong penetration welding of both of the polymer parts.
Most thermoplastic and thermoplastic materials can be welded using diode laser radiation. For example, many if not all of the example materials listed below, even those materials reinforced with glass fibers, are suitable materials that provide a welding seam strength that is comparable to that of the base polymer material itself.
The use of diode lasers for a heat bond provide a number of advantages including a non-contact, flexible joining technique that results in minimal thermal stress on the polymer parts that are welded together. A diode laser provides a simple joining seam geometry without particulate development. A diode laser bond is a vibration-free process that provides optimal welding seam construction with high precision and a resulting high strength bond. The resultant seal generated between the various polymer parts is gas-tight and hermetic. Typically, there is no toolware involved nor any consumable material used (e.g., adhesives, fasteners, etc.) when using a diode laser to create the desired thermobond of catheter shafts.
An example diode bonding arrangement and related processes is described now with reference to
In an example where the lens 466 is a cylindrical lens, the resulting focused beam 470 has an oval shape at the weld area 450. The beam in one example can have a maximum width dimension of 5.0 mm. In some arrangements, the maximum width dimension of the beam 470 of
An example method of bonding two catheter shafts using a diode laser is now described:
Materials used in the balloons, catheter shafts, and other components of the catheter assemblies disclosed herein can be made of any suitable material including, for example, thermoplastic polymers, polyethylene (high density, low density, intermediate density, linear low density), various co-polymers and blends of polyethylene, ionomers, polyesters, polycarbonates, polyamides, poly-vinyl chloride, acrylonitrile-butadiene-styrene copolymers, polyether-polyester copolymers, and polyetherpolyamide copolymers. One suitable material is Surlyn®, a copolymer polyolefin material (DuPont de Nemours, Wilmington, Del.). Still further suitable materials include thermoplastic polymers and thermoset polymeric materials, poly(ethylene terephthalate) (commonly referred to as PET), thermoplastic polyamide, polyphenylene sulfides, polypropylene. Some other example materials include polyurethanes and block copolymers, such as polyamide-polyether block copolymers or amide-tetramethylene glycol copolymers. Additional examples include the PEBAX® (a polyamide/polyether/polyester block copolymer) family of polymers, e.g., PEBAX® 70D, 72D, 2533, 5533, 6333, 7033, or 7233 (available from Elf AtoChem, Philadelphia, Pa.). Other examples include nylons, such as aliphatic nylons, for example, Vestamid L21011F, Nylon 11 (Elf Atochem), Nylon 6 (Allied Signal), Nylon 6/10 (BASF), Nylon 6/12 (Ashley Polymers), or Nylon 12. Additional examples of nylons include aromatic nylons, such as Grivory (EMS) and Nylon MXD-6. Other nylons and/or combinations of nylons can also be used. Still further examples include polybutylene terephthalate (PBT), such as CELANEX® (available from Ticona, Summit, N.J.), polyester/ether block copolymers such as ARNITEL® (available from DSM, Erionspilla, Ind.), e.g., ARNITEL® EM740, aromatic amides such as Trogamid (PA6-3-T, Degussa), and thermoplastic elastomers such as HYTREL® (Dupont de Nemours, Wilmington, Del.). In some embodiments, the PEBAX®, HYTREL®, and ARNITEL® materials have a Shore D hardness of about 45D to about 82D. The balloon materials can be used pure or as blends. For example, a blend can include a PBT and one or more PBT thermoplastic elastomers, such as RITEFLEX® (available from Ticona), ARNITEL®, or HYTREL®, or polyethylene terephthalate (PET) and a thermoplastic elastomer, such as a PBT thermoplastic elastomer. Additional examples of balloon material can be found in U.S. Pat. No. 6,146,356. It should be understood that the specific materials disclosed below for the individual embodiments does not limit the embodiment to those materials.
While the example catheter system 10 described above illustrates a balloon expandable stent having a predetermined branch aperture, other types of stents can be used with the catheter features described above. A variety of stents can be used with the systems and methods disclosed herein. Examples of such stents can be found in, for example, in U.S. Pat. Nos. 6,210,429, 6,325,826, and 7,220,275 the entire contents of which are incorporated herein by reference. In general, the aforementioned stents have a tubular shape with a continuous sidewall that extends between the proximal and distal ends. Proximal and distal stent apertures are defined at respective proximal and distal ends of the stent. A branch aperture is defined in the sidewall of the stent. The branch aperture provides access between an interior of the stent and an exterior of the stent. In some stents, the branch aperture includes expandable structure around a peripheral edge thereof that expands in a generally radial outward direction relative to a longitudinal axis of the stent. The expandable structure can be configured to extend into the branch lumen of the bifurcation upon expansion of the stent. The stent includes a plurality of strut structures that define the sidewall. The struts are expandable from a first, unexpanded state to a second, expanded state. Typically, the stent is configured to maintain the expanded state. The struts define a plurality of cell openings or cells along a length of the stent. The size and shape of the cells is typically different than the size and shape of the branch aperture. The stent is typically expanded once the stent is properly positioned in the main lumen of the bifurcation with the branch aperture aligned radially and axially with an opening into the branch lumen. The stent, including the expandable structure surrounding the branch aperture, can be expanded with a single expansion or with multiple expansions using, for example, one or more inflatable balloons.
One aspect of the present disclosure relates to a catheter shaft bond arrangement that includes a first catheter shaft, a second catheter shaft, and a first bonding member. The first catheter shaft defines a first lumen. The second catheter shaft defines a second lumen. The first bonding member is configured to bond with the first and second catheter shafts to create a molded bond upon application of heat to the first bonding member. The molded bond provides a fixed axial and radial orientation of the first and second catheter shafts relative to each other.
Another aspect of the present disclosure relates to a catheter shaft bond member. The bond member includes an elongate shaft of material, a first bore, and a second bore. The elongate shaft includes a polymeric material. The first bore is defined in the elongate shaft. The first bore has a first internal dimension sized to receive a first catheter shaft. The second bore is defined in the elongate shaft and includes a second internal dimension that is sized to receive a second catheter shaft. The polymeric material of the elongate shaft is configured to bond with the first and second catheter shafts upon application of heat to the elongate shaft.
A further aspect of the present disclosure relates to a method of connecting first and second catheter shafts together in a fixed axial and radial orientation relative to each other. The method includes positioning the first and second catheter shafts adjacent to each other, positioning a first bonding member adjacent to the first and second catheter shafts, and applying heat to the first bonding member, wherein the applied heat creates a heat bond between the first bonding member and the first and second catheter shafts. The heat bond provides fixed axial and radial orientation of the first and second catheter shafts relative to each other.
A still further aspect of the present disclosure relates to a method of creating a bond between first and second catheter shafts. The method includes engaging an outer surface of the first catheter shaft with an outer surface of the second catheter shaft, and applying heat in the area of contact between the first and second catheter shafts, the applied heat creating a heat bond between the first and second catheter shafts.
The above specification, examples and data provide a complete description of the manufacture and use of the composition of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended.
