COMPOSITE POLYESTER MATERIAL HAVING A LUBRICOUS SURFACE

Abstract: A low friction intravascular catheter component formed of a polyester matrix having incorporated therein a finely divided lubricous particulate which is preferably one or more suitable lubricous particulate selected from the group consisting of graphite, molybdenum disulfide, TiC, MoC, graphite difluoride, and fluoropolymers. The polyester is preferably a copolymer with a predominant amount of polybutylene terephthalate and lesser amounts of components such as polytetramethylene ether glycol which has been esterified with dimethyl terephthalate, e.g. HYTREL3. Typical components made of this low-friction material include the inner or outer tubular members of fixed-wire and over-the-wire dilatation catheters. A polysiloxane fluid may be incorporated within the matrix along with the lubricous particulate matter.

Description: COMPOSITE POLYESTER MATERIAL HAVING A LUBRICOUS SURFACE RELATED APPLICATIONS This application is a continuation-in-part application of application Serial No. 08/134,863, filed on October 12, 1993, entitled COMPOSITE MATERIAL HAVING A LUBRICOUS SURFACE FOR CATHETER USE, which is a continuation of application Serial No. 07/833,369, filed on February 10, 1992, entitled COMPOSITE MATERIAL HAVING A LUBRICOUS SURFACE FOR CATHETER USE. BACKGROUND OF THE INVENTION This invention generally relates to intraluminal catheters, such as guiding catheters and balloon dilatation catheters used in percutaneous transluminal coronary angioplasty (PTCA). In classic PTCA procedures, a guiding catheter having a preshaped distal tip is percutaneously introduced by a Seldinger technique into the cardiovascular system of a patient and advanced therein until the preshaped distal tip of the guiding catheter is disposed within the aorta adjacent the ostium of the desired coronary artery. The guiding catheter is twisted or torqued from the proximal end to turn the distal tip of the guiding catheter so that it can be guided into the desired coronary ostium. In over-the-wire systems, a guidewire and a balloon dilatation catheter are introduced into and advanced through the guiding catheter to the distal 1 SUBST'TU F c .i J E" fRl !LF 26) tip thereof, with the guidewire slidably disposed within an inner lumen of the dilatation catheter. The guidewire is first advanced out the distal tip of the guiding catheter, which is seated in the ostium of the patient's coronary artery, until the distal end of the guidewire crosses the lesion to be dilated. The dilatation catheter is then advanced out of the distal tip of the guiding catheter, over the previously advanced guidewire, until the balloon on the distal extremity of the dilatation catheter is properly positioned across the lesion. Once properly positioned, the balloon is inflated to a predetermined size with radiopaque liquid at relatively high pressures (e.g. , generally 4-1 2 atmospheres) to dilate the stenosed region of the diseased artery. One or more inflations may be necessary to effectively dilate the stenosis. Additional stenoses may be dilatated with the same catheter. When the dilatations are completed, the balloon is deflated so that the dilatation catheter can be removed from the dilated stenosis and blood flow will resume through the dilated artery. Further details of guiding catheters, dilatation catheters, guidewires, and other devices for angioplasty procedures can be found in U.S. Patent 4,323,071 (Simpson-Robert); U.S. Patent 4,439, 185 (Lundquist); U.S. Patent 4,468,224 (Enzmann et al. ); U.S. Patent 4,516,972 (Samson); U.S. Patent 4,438,622 (Samson et al. ); U.S. Patent 4,554,929 (Samson et al. ); U.S. Patent 4,582, 185 (Samson); U.S. Patent 4,61 6,652 (Simpson); U.S. Patent 4,638,805 (Powell); U.S. Patent 4,748,986 (Morrison et al. ); U.S. Patent 4,898,577 (Badger et S! IDCT1Η 'T (RULE 26"! al. ); and U.S. Patent 4,827,943 (Taylor et al.) which are incorporated herein in their entirety by reference thereto. Fixed-wire dilatation catheters for coronary angioplasty, which were first described in U. S. Patent 4,252,181 (Samson) now Reissue patent 33,166, are similarly used except there is no longitudinal movement between the guidewire and the catheter. The fixed-wire dilatation catheters generally have an outer tubular member with an inflatable balloon on the distal section thereof which is capable of dilating a stenosis, and a guiding member extending out through the distal end of the balloon which aids in advancing the catheter to a desired location within the patient's vasculature. They also usually have no inner tubular member and therefore have lower profiles, e.g. transverse dimensions, than over-the-wire dilatation catheters having the same inflated balloon size. Moreover, because the fixed-wire catheters have the guidewire or guiding member fixed or at least restricted as to longitudinal movement, these catheters generally have greater pushability than over-the-wire type catheters such as described and claimed in U.S. Patent 4,323,071 (Simpson-Robert). The lower profile and greater pushability of the fixed- wire dilatation catheters allows them to cross tighter lesions and to be advanced much deeper into a patient's coronary anatomy than the over- the-wire dilatation catheters of comparable sizes. Various improvements have been made to intravascular catheters used in angioplasty and other intravascular procedures. Of particular note is a rapid exchange type catheters described and claimed SUBSTITU T E SHEET (PULE 26l in U.S. Patent 5,040,548 (Yock), U.S. Patent 5,061 ,273 (Yock), and U.S. Patent 4,748,982 (Horzewski et al.), which are incorporated herein in their entirety by reference. The rapid exchange type dilatation catheter has a short guidewire receiving sleeve or inner lumen extending through the flexible distal portion of the catheter which extends out of the guiding catheter into the patient's coronary artery during the angioplasty procedure. The sleeve extends proximally a distance of at least 10 cm and usually not more than about 50 cm from a first guidewire port in the distal end of the catheter to a second guidewire port in the catheter spaced proximally from the inflatable balloon of the catheter. A slit, as described in Horzewski et al. , is preferably provided in the catheter wall which extends distally from the second guidewire port, preferably to a location proximal to the proximal end of the inflatable balloon to aid in the removal of the catheter from a guidewire. The structure of the catheter allows for the rapid exchange of the catheter without the need for the use of an exchange wire or adding a guidewire extension to the proximal end of the guidewire. The design of this catheter has been widely praised by the medical profession and has met with much commercial success in the market place because of its unique design. A substantial improvement in the rapid exchange type dilatation catheters, such as described above, has recently been made by Mclnnes et al. which is described in copending applications Serial No. 07/476,056, filed February 7, 1990 and Serial No. 07/541 ,264 filed June 19, 1990, both entitled READILY EXCHANGEABLE PERFUSION SUBSTΓ l i. Oι DILATATION CATHETER, and which are incorporated herein by reference. In these rapid exchange type dilatation catheters, perfusion ports are provided in the catheter shaft, proximal and distal to the balloon, which are in fluid communication with the guidewire receiving inner lumen to allow blood to perfuse distal to the catheter when the balloon is inflated. Lubricous coatings have been applied to the surfaces of guiding catheters, dilatation catheters and other intraluminal catheters in order to reduce the friction between the surfaces of these catheters and other components of the catheter systems in which the catheters are employed during the intravascular procedures. For example, fluoropolymer linings such as Teflon ® are very frequently employed as the inner linings of guiding catheters in order to reduce the friction between the inner lining of the guiding catheter and the guidewire and the catheters which might be advanced through the inner lumen of the guiding catheter. Lubricous silicone coatings have been applied to the surfaces of guidewires and of dilatation catheters to likewise reduce the frictional characteristics of these devices. However, the application of these lubricous coatings and linings are for the most part complicated manufacturing processes. Moreover, very frequently these coatings and linings are not very durable and lose substantial portions of their lubricity during the intraluminal or intravascular procedure. What has been needed and heretofore unavailable is a durable high strength plastic surface having long lasting lubricity which does not require complicated manufacturing procedures. The present Ql i ITH ' f IIP CU' rr ιa> !L L <_ΪJ; invention satisfies this and other needs. SUMMARY OF THE INVENTION The present invention is directed to an improved composite plastic material having a very durable lubricous surface and particularly to tubular products for intraluminal catheter procedures within a human patient made from such composite materials. The material of the invention generally includes a biocompatible polymer matrix having finely divided lubricous particulate matter incorporated within the matrix. The polymer matrix can be formed of thermoplastic materials, particularly thermoplastic polyesters are preferred when the final product has a tubular shape because thermoplastic polyesters can be easily extruded or otherwise formed in a conventional fashion and can be more readily joined to other components. When the lubricous particulate is well dispersed within the polymer matrix prior to or during the extrusion or other melt processing, the extrusion pressure or other forces needed to form the product are significantly lowered and there is much better dimensional control during the extrusion process than the same plastic materials without the lubricous particulate matter incorporated therein. Increased strengths in addition to decreased frictional characteristics are also obtained by the incorporation of the lubricous particulate. The coefficient of friction of this material ranges from about 0.03 to about SUBSTITUT HPFT ' n !J! E 2 (Λ6) 0.20. The tubular products of the invention can be formed into the shafts for intraluminal catheters such as balloon dilatation catheters for angioplasty procedures in a conventional manner. The presently preferred polyester matrix is a polyester sold under the trademark HYTREL ® by DuPont, particularly grades 7246 and 8238. HYTREL is believed to be a copolymer of predominantly polybutylene terephthalate and a lesser amount of polytetramethylene ether glycol esterified with dimethyl terephthalate. Other minor components may be included. These and other advantages of the invention will become more apparent from the following detailed description of the invention when taken in conjunction with the accompanying exemplary drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an elevational view, partially in section of a balloon dilatation catheter embodying features of the invention. Fig. 2 is a transverse cross-sectional view of the catheter shown in Fig. 1 taken along the lines 2-2. Fig. 3 is a transverse cross-sectional view of the catheter shown in Fig. 1 taken along the lines 3-3. DETAILED DESCRIPTION OF THE INVENTION Figs. 1 -3 illustrate a balloon dilatation catheter which SUBSTITUTE iEE ' (RULE 26) embodies features of the invention. The dilatation catheter generally includes an outer tubular member 10, a dilatation balloon 11 on the distal portion of the outer tubular member, an inner member 12 disposed within the outer tubular member and the balloon and a multi-arm adapter 13 mounted on the proximal ends of the inner and outer tubular members. The distal end of the balloon 1 1 is sealed about the distal end of the inner tubular member 12 so that injection of inflation fluid under significant pressure through annular lumen 14 to the interior of the balloon will result in the inflation thereof. A guidewire 15 is slidably disposed within the inner lumen 16 of the inner tubular member 12. The distal end of the catheter is provided with a self venting means such as described in U.S. Patent 4,638,805 (Powell). A radiopaque marker 17 is disposed about the inner tubular member 12 at the mid-point of the balloon 1 1 to facilitate the fluoroscopic observation thereof during an angioplasty procedure. The brachial marker 20 and femoral marker 21 are provided on the proximal end of the inner tubular member 12. In accordance with the invention, the inner tubular member 12 is formed of composite material which generally includes a polymer matrix, preferably a readily extrudable thermoplastic polyester and incorporated within the polyester matrix is a finely divided lubricous particulate matter which range on the average from about 0.1 to about 100 microns, preferably about 0.5 to about 20 microns, in maximum dimensions. The amount of particulate matter in the polymer matrix 8 SUBSTITUTE ^-E fR' LE 2 , thereof may range from about 0.5 to about 50%, preferably about 2 to about 20%, of the precured mixture thereof. As used herein all percentages are weight percent unless noted otherwise. Up to about 1 % of a dispersing agent, such as lecithin, silicone oil, vegetable oil, polyethylene wax or mixtures thereof, may be incorporated into the mixture to facilitate effective mixing of the particulate within the polymer resin. However, with HYTREL it has been found that the graphite particles can be fed into the extruder along with the HYTREL to provide effective dispersing. Particularly suitable lubricous particulate materials include graphite, fluoropolymers such as Teflon ® , molybdenum disulfide, titanium carbide, molybdenum carbide, graphite difluoride or mixtures thereof. Presently preferred lubricous particulate include Micro 850 and Micro 250 graphite available from the Asbury Graphite Mills, located in Asbury County, New Jersey. This graphite has an average maximum particle size from about 3 to about 10 microns in maximum dimension. In addition, silicone oils such as dimethylsiloxane polymers with a viscosity between about 300 and 100,000 centipoise, preferably about 1000 to about 30,000 centipoise, can be incorporated along with the solid lubricous particulate in amounts of up to 10%, preferably about 0.5 to about 4%. Formation of the products of the invention typically involve intimately mixing the lubricous particulate into the uncured or partially cured polymer resin which forms the matrix of the cured product. If needed, a dispersant may be first mixed with the lubricous particulate to SUBSΠTUTE SWF. • ft facilitate a more uniform dispersement of the particulate throughout the uncured resin. The dispersant may be advantageously added to the lubricous particulate as a solution of isopropyl alcohol or other suitable solvent to facilitate the incorporation thereof. The finely divided lubricous particulate has a tendency to agglomerate and an intimate and uniform mixture of the particulate within the polymer matrix can be very difficult to obtain without a dispersant. The polymer-particulate mixture is then preferably extruded in a conventional manner into a tubular product having the desired dimensions. After extruding, the tubular product is then cured. To illustrate a presently preferred embodiment, a mixture was prepared containing 96% of HYTREL (Grade 7246) and 4% graphite powder and extruded into pellets. The pellets are extruded into a tubular product. The tubular member is then cut to length and used in the manufacture of a prototype dilatation catheter as shown in Figs. 1-3. The tubular member will have a low coefficient of friction. While the invention has been described herein primarily in terms of an inner tubular member for an over-the-wire type dilatation catheter of concentric design, the composite material of the invention can be utilized in a wide variety intraluminal catheter components. For example, the material can be used to form the outer tubular member in an over-the-wire dilatation catheter or a fixed-wire dilatation catheter. All or a portion of the outer tubular member may be formed of the polymer 10 SUBS^ SH F ' ; :.E 2S matrix-finely divided lubricous particulate. The material can also be used to form the inflatable member or balloon of a dilatation catheter. Guidewire receiving inner tubular members such as described in the Yock and Horzewski et al. patents, which have been incorporated herein, may be made of the composite material formed of polymer and low friction particulate. Another use is the formation of guiding catheters in which the composite material is used to form at least the inner liner of the catheter to provide the lubricous inner lumen required in this type of intravascular catheter. Other uses include shafts and inflatable members of urethral dilatation catheters and Foley type catheters. While the invention is described herein in terms of certain presently preferred embodiments, those skilled in the art will recognize that various changes and improvements can be made to the present invention without departing from the scope thereof. 1 1 SUBSTITU T SHEET (RULE 2ff>

Claims: WHAT IS CLAIMED IS: 1 . A composite material comprising a polymer matrix consisting essentially of one or more thermoplastic polyesters and finely divided lubricous particulate material. 2. The composite material of claim 1 wherein the polyester matrix is biocompatible material. 3. The composite material of claim 1 wherein the lubricous particulate material is selected from the group consisting of graphite, molybdenum disulfide, TiC, MoC, graphite difluoride, fluoropolymers and mixtures thereof. 4. The composite material of claim 1 wherein the lubricous particulate material has an average particle size of about 0.1 to about 100 microns in maximum dimension. 5. The composite material of claim 1 wherein the lubricous particulate has an average particle size of about 0.5 to about 20 microns in maximum dimension. 6. The composite material of claim 1 including a silicone oil incorporated within the matrix. 12 SUBSTITUTE SHEET 7. The composite material of claim 1 containing from about 1 to about 50% lubricous particulate matter. 8. The composite material of claim 1 containing from about 2 to > about 20% lubricous particulate matter. 9. The composite material of claim 1 formed from a mixture of polyester, lubricous particulate matter and from about 0.01 to about 5% of a dispersing agent. 10. The composite material of claim 1 formed from a mixture of polyester, lubricous particulate matter and from about 0.05 to about 1 % of a dispersing agent. 11 . The composite material of claim 10 wherein the dispersing agent is selected from the group consisting of lecithin, silicone oil, vegetable oil, polyethylene wax and mixtures thereof. 12. The composite material of claim 1 having a coefficient of friction from about 0.03 to about 0.2. 13. The composite material of claim 1 wherein the polyester is a copolymer predominantly polybutlyene terephthalate. 13 SUBSTITUTE SUf- ' 'D: 14. The composite material of claim 13 wherein the copolymer contains a minor amount of polytetramethylene ether glycol esterified with dimethyl terephthalate. 15. The composite material of claim 14 wherein the ester has a molecular weight of about 600 to about 3000. 16. A method for making a component for an intravascular catheter having a durable lubricous coating thereon comprising: a) mixing a biocompatible thermoplastic polyester with lubricous particulate; and b) forming the polyester-particulate mixture into a desired shape for the component. 17. The method of claim 16 wherein the polyester-particulate mixture is formed into a desired shape by extruding the mixture. 18. The method of claim 17 wherein the desired shape is a hollow tube. 19. The method of claim 16 wherein the lubricous particulate is selected from the group consisting of graphite, molybdenum disulfide, TiC, MoC, graphite difluoride, fluoropolymers and mixtures thereof. 20. The method of claim 19 wherein the lubricous particulate 14 sussrmrrF. --F T " * • . ? > material has an average particle size of about 0.1 to about 100 microns in maximum dimension. 21. The method of claim 19 wherein the lubricous particulate material has an average particle size of about 0.5 to about 20 microns in maximum dimension. 22. The method of claim 19 wherein the amount of lubricous particulate matter ranges from about 0.5 to about 50%. 23. The method of claim 19 wherein the amount of lubricous particulate matter ranges from about 1 to about 25%. 24. The method of claim 19 wherein from about 0.05 to about 1 % of a dispersing agent is mixed with the polyester and lubricous particulate matter. 25. The method of claim 24 wherein the dispersing agent is selected from the group consisting of lecithin, silicone oil, vegetable oil, polyethylene wax and mixtures thereof. 26. An intravascular catheter comprising an elongated tubular element having a thermoplastic polyester matrix and finely divided lubricous particulate material well dispersed within the matrix. 15 SUBSTΠTJT ' SHFET ,'PULE 261 27. The intravascular catheter of claim 26 wherein the tubular element is a first inner tubular member which is disposed within a second outer tubular member. 28. The intravascular catheter of claim 26 wherein the tubular element is an outer tubular member. 29. The intravascular catheter of claim 26 wherein the thermoplastic polyester matrix comprises a copolymer including a predominant amount of polybutylene terephthalate. 30. The intravascular catheter of claim 26 wherein the lubricous particulate material is selected from the group consisting of graphite, molybdenum disulfide, TiC, MoC, graphite difluoride, fluoropolymers and mixtures thereof. 31 . The intravascular catheter of claim 30 wherein the lubricous particulate material has an average particle size of about 0.1 to about 100 microns in maximum dimension. 32. The intravascular catheter of claim 30 wherein the lubricous particulate has an average particle size of about 0.5 to about 20 microns in maximum dimension. 1 6 UBS fTirE Sμ^, ,,r,i !; p 7F , 33. The intravascular catheter of claim 30 wherein the amount of lubricous particulate matter ranges from about 0.5 to about 50%. 34. The intravascular catheter of claim 30 wherein the amount of lubricous particulate matter ranges from about 1 to about 25%. 35. The intravascular catheter of claim 30 wherein the tubular member includes from about 0.01 to about 5% of a dispersing agent. 36. The intravascular catheter of claim 30 wherein the tubular member includes from about 0.05 to about 1 % of a dispersing agent. 37. The intravascular catheter of claim 36 wherein the dispersing agent is selected from the group consisting of lecithin, silicone oil, vegetable oil, polyethylene wax and mixtures thereof. 38. The intravascular catheter of claim 30 wherein the tubular element has a short guidewire receiving inner lumen of a readily exchangeable dilatation catheter. 39. A dilatation catheter comprising: a) an elongated catheter shaft which has an inner inflation lumen extending therein, which has a first tubular member with a guidewire receiving inner lumen extending therein, the first tubular member formed of a thermoplastic polyester polymer matrix with about 0.5 to about 20% of finely divided, solid lubricous particulate consisting essentially of graphite particles less than 100 microns in size dispersed within the matrix; and b) an inflatable dilatation member on a distal portion of the elongated catheter shaft having an interior in fluid communication with the inner inflation lumen extending within the catheter shaft. 40. The dilatation catheter of claim 39 wherein the polyester comprises a co-polymer of polybutylene terephthalate and polytetramethylene ether glycol esterified with dimethyl terephthalate 18 SUBS T ; T UTE SriEET ' Lr

Inventors: AINSWORTH ROBERT D, CHENG TAI C, HARRINGTON DOUGLAS C, AINSWORTH, ROBERT, D., CHENG, TAI, C., HARRINGTON, DOUGLAS, C.
Applicants: ADVANCED CARDIOVASCULAR SYSTEM, ADVANCED CARDIOVASCULAR SYSTEMS, INC.
Application year: 1995
Main classification: A61L29
IPC codes: A61L29, A61M25, A61M29, C08K3, C08K5, C08L67, C08L83