WO2000012145A1

WO2000012145A1 - Aliphatic polyketone containing balloon catheter

Info

Publication number: WO2000012145A1
Application number: PCT/US1999/018925
Authority: WO
Inventors: Stephen Schaible
Original assignee: Advanced Cardiovascular Systems, Inc.
Priority date: 1998-08-27
Filing date: 1999-08-17
Publication date: 2000-03-09
Also published as: AU5680499A

Abstract

An intraluminal catheter having a component formed at least in part of an aliphatic polyketone material. In a presently preferred embodiment, the intraluminal catheter is a balloon catheter having a balloon formed of a polymeric material comprising the aliphatic polyketone material. The balloon of the invention exhibits high tensile strength, high elongation, and low flexural modulus. In a presently preferred embodiment, the aliphatic polyketone is a linear alternating polymer of carbon monoxide and at least one ethylenically unsaturated hydrocarbon, such as a thermoplastic polymer sold under the trade name CARILON®. The balloon may be 100 % aliphatic polyketone or blended with another polymer.

Description

ALIPHATIC POLYKETONE CONTAINING BALLOON CATHETER

This invention generally relates to intraluminal catheters, such as balloon dilatation catheters used in percutaneous transluminal coronary angioplasty

(PTCA).

PTCA is a widely used procedure for the treatment of coronary heart disease. In this procedure, a balloon dilatation catheter is advanced into the patient's coronary artery and the balloon on the catheter is inflated within the stenotic region of the patient's artery to open up the arterial passageway and thereby increase the blood flow there through. To facilitate the advancement of the dilatation catheter into the patient's coronary artery, a guiding catheter having a preshaped distal tip is first percutaneously introduced into the cardiovascular system of a patient by the Seldinger technique through the brachial or femoral arteries. The catheter is advanced until the preshaped distal tip of the guiding catheter is disposed within the aorta adjacent the ostium of the desired coronary artery, and the distal tip of the guiding catheter is then maneuvered into the ostium. A balloon dilatation catheter may then be advanced through the guiding catheter into the patient's coronary artery until the balloon on the catheter is disposed within the stenotic region of the patient's artery. The balloon is inflated to open up the arterial passageway and increase the blood flow through the artery. Generally, the inflated diameter of the balloon is approximately the same diameter as the native diameter of the body lumen being dilated so as to complete the dilatation but not over expand the artery wall. After the balloon is finally deflated, blood flow resumes through the dilated artery and the dilatation catheter can be removed therefrom.

To reduce the restenosis rate and to strengthen the dilated area, physicians frequently implant an intravascular prosthesis, generally called a stent, inside the artery at the site of the lesion. Stents may also be used to repair vessels having an intimal flap or dissection or to generally strengthen a weakened section of a vessel. Stents are usually delivered to a desired location within a coronary artery in a contracted condition on a balloon of a catheter which is similar in many respects to a balloon angioplasty catheter, and expanded to a larger diameter by expansion of the balloon. The balloon is deflated to remove the catheter and the stent left in place within the artery at the site of the dilated lesion. See for example, U.S. Pat. No. 5,507,768 (Lau et al.) and U.S. Pat. No. 5,458,615 (Klemm et al.), which are incorporated herein by reference. The implantation of a stent at the site of the dilatation can significantly reduce the restenosis rate.

The balloons for prior dilatation catheters utilized in angioplasty procedures generally have been formed of relatively inelastic polymeric materials such as polyvinyl chloride, polyethylene, polyethylene terephthalate (PET), polyolefinic ionomers, and nylon. An advantage of such inelastic materials when used in catheter balloons is that the tensile strength, and therefore the mean rupture pressure, of the balloon is high. Catheter balloons must have high tensile strength in order to exert sufficient pressure on the stenosed vessel and effectively open the patient's passageway. Consequently the high strength balloon can be inflated to high pressures without a risk that the balloon will burst during pressurization. Similarly, the wall thickness of high strength balloons can be made thin, in order to decrease the catheter profile, without a risk of bursting. Additionally, the inelastic material provides balloons having minimal and controlled expansion, which therefore avoids trauma to the patient's vessel caused by over expansion of the balloon.

Many inelastic materials used to form a catheter balloon, including PET and nylon, are relatively hard. The hardness of these materials impairs the ability of the catheter to track the tortuous vasculature of the patient and cross the stenosis. Thus, a soft balloon is preferable, to improve the trackability of the catheter and the ability of the catheter to effectively position the balloon at the stenosis.

Therefore, what has been needed is a relatively soft catheter balloon having a high rupture pressure. The present invention satisfies these and other needs.

SUMMARY OF THE INVENTION

The invention is directed to an intraluminal catheter having a component formed at least in part of an aliphatic polyketone material. In a presently preferred embodiment, the intraluminal catheter is a balloon catheter having a balloon formed of a polymeric material comprising the aliphatic polyketone material. The balloon of the invention exhibits high rupture and tensile strength, high elongation, and low flexural modulus.

Aliphatic polyketones generally comprise polymers of carbon monoxide and olefins. In a presently preferred embodiment, the aliphatic polyketone is a linear alternating polymer of carbon monoxide and at least one ethylenically unsaturated hydrocarbon, such as a semi-crystalline thermoplastic polymer sold under the trade name CARILON®, available from Shell Oil Company. CARILON® is described in U.S. Patents 5,049,650 and 4,940,777, which are incorporated herein by reference. Aliphatic polyketones provide high rupture and fatigue strength balloons which have improved trackability due to the softness of the material. The softness of a balloon is expressed in terms of the balloon modulus, where a relatively soft balloon has a relatively low flexural modulus.

The presently preferred balloon is formed from 100% aliphatic polyketone. However, the balloon can be formed of a blend of aliphatic polyketone with one or more different polymeric materials. Suitable polymeric materials for blending with the aliphatic polyketone include those thermoplastic polymers listed above used to make balloons for prior dilatation catheters, such as olefinic polymers and polyamides, or aromatic polyketones such as polyetheretherketone. In a presently preferred embodiment, the balloon is a single polymeric layer. However, the balloon may also be multilayered, where the balloon is formed by coextruding two or more layers with one or more layers formed at least in part of aliphatic polyketone.

The balloon catheter of the invention generally comprises a catheter having an elongated shaft with an inflatable balloon. Various designs for balloon catheters well known in the art may be used in the catheter of the invention having a balloon formed at least in part aliphatic polyketone. For example, the catheter may be a conventional over-the-wire dilatation catheter for angioplasty having a guidewire receiving lumen extending the length of the catheter shaft from a guidewire port in the proximal end of the shaft, or a rapid exchange dilatation catheter having a short guidewire lumen extending to the distal end of the shaft from a guidewire port located distal to the proximal end of the shaft.

Additionally, the catheter may be used to deliver a stent mounted on the catheter balloon.

The aliphatic polyketone material will provide a balloon with thin walls having high rupture and tensile strength, and a relatively low flexural modulus. Thus, the balloon of the invention formed at least in part of aliphatic polyketone material, combines improved softness and tensile strength, to provide low profile balloon catheters having excellent ability to tract the patient's vasculature, cross the stenosis, and compress the stenosis to open the patient's vessel. These and other advantages of the invention will become more apparent from the following detailed description of the invention and the accompanying exemplary drawings. BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is an elevational view, partially in section, of the catheter of the invention showing the balloon in an unexpanded state within a patient's body lumen. Fig. 2 is a transverse cross sectional view of the catheter of Fig. 1 taken along lines 2-2.

Fig. 3 is a transverse cross sectional view of the catheter of Fig. 1 taken along lines 3-3.

Fig. 4 is an elevational view, partially in section, of the catheter of Fig. 1 , showing the balloon in an expanded state within the body lumen.

Fig. 5 is a transverse cross sectional view of the catheter of Fig. 4 taken along lines 5-5.

Fig. 6 is an elevational view of the catheter of Fig. 4, showing the balloon deflated with the stent expanded within the body lumen.

DETAILED DESCRIPTION OF THE INVENTION

As shown in Fig. 1 , the catheter 10 of the invention generally includes a an elongated catheter shaft 11 having a proximal section 12 and distal section 13, an inflatable balloon 14, formed at least in part of aliphatic polyketone, on the distal section 13 of the catheter shaft 11 , and an adapter 17 mounted on the proximal section 12 of shaft 11 to direct inflation fluid to the interior of the inflatable balloon. Figs. 2 and 3 illustrate transverse cross sections of the catheter shown in Fig. 1 , taken along lines 2-2 and 3-3 respectively.

In the embodiment illustrated in Fig. 1 , the intravascular catheter 10 of the invention is an over-the-wire catheter, and is illustrated within a patient's body lumen 18 with the balloon 14 in an unexpanded state. The catheter shaft 11 has an outer tubular member 19 and an inner tubular member 20 disposed within the outer tubular member and defining, with the outer tubular member, inflation lumen 21. Inflation lumen 21 is in fluid communication with the interior chamber 15 of the inflatable balloon 14. The inner tubular member 20 has an inner lumen 22 extending therein, which is configured to slidably receive a guidewire 23 suitable for advancement through a patient's coronary arteries. The distal extremity of the inflatable balloon 14 is sealingly secured to the distal extremity of the inner tubular member 20 and the proximal extremity of the balloon is sealingly secured to the distal extremity of the outer tubular member 19.

In a presently preferred embodiment, the aliphatic polyketone material is a linear alternating polymer have a repeating unit of the general formula -CO- (A)-, wherein A is a moiety of ethylenically unsaturated hydrocarbon which may be polymerized through the ethylenic linkage. A variety of ethylenically unsaturated hydrocarbons, preferably of up to 20 carbon atoms inclusive, and most preferably up to 10 carbon atoms inclusive, may be used. Illustrative of such hydrocarbons are ethylene, propylene, 1-butene, isobutylene, hexene, styrene, 1-octene and 1-dodecene.

The preferred linear alternating polymers are copolymers of carbon monoxide and ethylene, or terpolymers of carbon monoxide, ethylene and a second ethylenically unsaturated hydrocarbon of at least 3 carbon atoms, particularly an -olefin such as propylene. The preferred linear alternating polymer material is represented by the repeating formula

[- CO(-CH₂-CH₂)_x[CO(-G]_y (I)

wherein G is a moiety of the second ethylenically unsaturated hydrocarbon of at least 3 carbon atoms, particularly propylene, polymerized through the ethylenic unsaturation thereof. Preferably, G has up to 20 carbon atoms inclusive, and is most preferably selected from the group consisting of propylene, 1-butene, isobutylene, hexene, styrene, 1-octene and 1-dodecene. The -CO(-CH₂CH₂)- units and -CO(-G)- units when present are generally found randomly throughout the polymer chain. Copolymers are represented by the above formula I wherein y is zero, and terpolymers are represented by the above formula I wherein y is greater than zero. Suitable linear alternating aliphatic polyketones include CARILON®, and preferably CARILON® grades D26FX100, D26CX100, and D26HM100.

The preferred aliphatic polyketone polymers have a melting point from about 175°C. to about 300°C, and typically about 220°C. The aliphatic polyketone polymers have a hardness of about 60 to about 150 hardness Rockwell, and preferably about 40 to about 60 hardness Rockwell (D785 test method), and a flexural modulus of about 150 kpsi (1 GPa) to about 300 kpsi (2 GPa), and typically about 230 kpsi (1.6 GPa). The general processes for polyketone production are illustrated by a number of published European patent applications, including Nos. 121 ,965, 181 ,014, 213,671 and 257,663, incorporated herein by reference.

The presently preferred aliphatic polyketone material has an elongation at break at about room temperature of at least about 150%, preferably about 300% or higher and up to a maximum of about 400%, and a tensile strength at break of at least about 6,000 psi (42 MPa), and preferably about 8,000 psi (55 Mpa) to about 9,200 psi (63 MPa) or higher and up to a maximum of about 10,000 psi. The flexural modulus of the material is about 180,000 psi (1240 Mpa) to about 300,000 psi (2070 Mpa), and preferably about 230,000 psi (1585 MPa). The balloon formed from the aliphatic polyketone material has sufficient strength to withstand the inflation pressures needed to inflate the balloon and compress a stenosis in a patient's vessel. The rupture pressure of the balloon is at least about 10 ATM, and is typically about 16-23 ATM. The flexural strength of the balloon is at least about 10,000 psi (69 MPa), and typically from about 15,000 psi (10 MPa) to about 25,000 psi (170 MPa).

As best illustrated in Fig. 3, the inflatable balloon 14 shown in Fig. 1 is formed of a single layer of polymeric material. The balloon may be 100% aliphatic polyketone or a aliphatic polyketone/polymer blend. In the embodiment in which CARILON® is blended with a different polymer, the presently preferred weight percent of CARILON® is from about 50% to about 95%, and most preferably about 70% to about 90%, of the total weight of the blend. The inflatable balloon 14 may also comprise multiple layers formed from coextruded tubing, in which one or more layers is at least in part formed from aliphatic polyketone.

The balloon of the invention can be produced by conventional techniques for producing catheter inflatable members, such as blow molding, and may be preformed by stretching a straight tube, at elevated temperatures, before the balloon is blown. The balloons may be formed by expansion of tubing, as for example at a hoop ratio of between about 3 and about 8. The presently preferred aliphatic polyketone balloon material is not crosslinked, although the balloon material may be crosslinked. The bonding of the balloon to the catheter may be by conventional techniques, such as adhesives and fusion with compatibilizers, as for example are described in U.S. Pat. No. 5,074,845 (Miraki et al.), incorporated by reference.

Fig. 2, showing a transverse cross section of the catheter shaft 11 , illustrates the guidewire receiving lumen 22 and inflation lumen 21. The balloon 14 can be inflated by radiopaque fluid from an inflation port 24 through inflation lumen 21 contained in the catheter shaft 11. The details and mechanics of balloon inflation vary according to the specific design of the catheter, and are well known in the art.

The length of the balloon 14 may be about 0.5 cm to about 6 cm, preferably about 1.0 cm to about 4.0 cm. After being formed, the outer diameter of the balloon at nominal pressure (e.g. 6-8 ATM) is generally about 1 mm to about 4 mm, and typically about 3 mm, although balloons having an outer diameter of about 1 cm may also be used. The single wall thickness is about 0.0004 in (0.0102 mm) to about 0.01 in (0.25 mm), and typically about 0.0015 in (0.0381 mm) to about 0.005 inches (0.13 mm), and more specifically about 0.0006 in (0.0152 mm). In the embodiment in which the coextrusion balloon has two layers, the inner layer single wall thickness is about .0003 in (0.0076 mm) to about .0006 in (0.0152 mm), and the outer layer is about .0002 in (0.0051 mm) to about .0005 in (0.0127 mm).

In the embodiment of the invention shown in Fig. 1 , a stent 16 is disposed about the balloon 14 for delivery within patient's vessel. The stent 16 may be any of a variety of stent materials and forms designed to be implanted by an expanding member, see for example U.S. Patent 5,514,154 (Lau et al.) and 5,443,500 (Sigwart), incorporated by reference. For example, the stent material may be stainless steel, a NiTi alloy or various other materials. The stent is shown in an unexpanded state in Fig. 1. The stent has a smaller diameter for insertion and advancement into the patient's lumen, and is expandable to a larger diameter for implanting in the patient's lumen. Fig. 4 illustrates the balloon 14 and stent 16 thereon expanded within the body lumen 18. Fig. 5 illustrates a transverse cross section of the catheter shown in Fig. 4, taken along lines 5-5. As illustrated in Fig. 6, the balloon is deflated and withdrawn from the body lumen, leaving the expanded stent implanted therein.

The following example more specifically illustrates the invention. Extrude CARILON® D26FX100 into tubular stock having 0.035 inch (0.889 mm) outer diameter (OD) and 0.019 in (0.483 mm) inner diameter (ID). Neck the tubing on one side at room temperature to ID of 0.018 in (0.457 mm). Using a glass mold at a temperature inside the mold of about 200°F-300°F (90°C-150°C ), preferably about 250°F (120°C), and a blow pressure of 325 psi (2240 kPa), form a balloon from the tubing having an OD of 3 mm, a length of 20 mm, and a working length wall thickness of 0.0006 in (0.0152 mm) to 0.0007 in (0.0178 mm). The mean rupture pressure of the balloons is expected to be about 300 psi (2070 kPa), and the tensile strength is expected to be about 15,000 psi (102 MPa).

It will be apparent from the foregoing that, while particular forms of the invention have been illustrated and described, various modifications can be made without departing from the spirit and scope of the invention. For example, while the balloon catheter illustrated in Fig. 1 has inner and outer tubular members with independent lumens, a single tubular membered shaft having two lumens therein may also be used. Additionally, while the catheter component comprising aliphatic polyketone is discussed in terms of a balloon, other catheter components including the catheter shaft may comprise aliphatic polyketone.

Other modifications may be made without departing from the scope of the invention.

Claims

WHAT IS CLAIMED IS:

1. An intraluminal catheter having a catheter component formed at least in part from an aliphatic polyketone material.

2. The intraluminal catheter of claim 1 wherein the catheter comprises an elongated shaft having a proximal end and a distal end, and a balloon formed at least in part from an aliphatic polyketone material on a distal shaft section.

3. The intraluminal catheter of claim 1 wherein the catheter comprises an elongated shaft having a proximal end and a distal end formed at least in part from an aliphatic polyketone material, and a balloon on a distal shaft section.

4. The intraluminal catheter of claim 1 wherein the aliphatic polyketone material comprises a linear alternating polymer of carbon monoxide and at least one ethylenically unsaturated hydrocarbon.

5. The intraluminal catheter of claim 4 wherein the linear alternating polymer is represented by the formula: -[CO-(CH₂-CH₂)]_x[CO-(G)]_Y

wherein G is a second ethylenically unsaturated hydrocarbon of at least 3 carbon atoms.

6. The intraluminal catheter of claim 5 wherein the second ethylenically unsaturated hydrocarbon has up to 20 carbon atoms.

7. The intraluminal catheter of claim 5 wherein the second ethylenically unsaturated hydrocarbon is selected from the group consisting of propylene, 1-butene, isobutylene, hexene, styrene, 1-octene, and 1-dodecene.

8. The intraluminal catheter of claim 5 wherein y is zero and the aliphatic polyketone material comprises a copolymer of carbon monoxide and ethylene.

9. The intraluminal catheter of claim 5 wherein aliphatic polyketone material comprises a terpolymer of carbon monoxide, ethylene, and propylene.

10. The intraluminal catheter of claim 1 wherein the balloon has a wall thickness, single wall basis, of about 0.01 mm to about 0.25 mm.

11. The intraluminal catheter of claim 1 wherein the aliphatic polyketone material has a tensile strength at break of about 6,000 psi to about 10,000 psi.

12. The intraluminal catheter of claim 1 wherein the aliphatic polyketone material has a tensile strength at break of about 8,000 psi to about 9,200 psi.

13. The intraluminal catheter of claim 1 wherein the aliphatic polyketone material has a hardness of about 60 to about 150 hardness

Rockwell.

14. The intraluminal catheter of claim 1 wherein the aliphatic polyketone material has a hardness of about 40 to about 60 hardness Rockwell.

15. The intraluminal catheter of claim 1 wherein the aliphatic polyketone material has a flexural modulus of about 150 kpsi to about 300 kpsi.

16. The intraluminal catheter of claim 1 wherein the catheter component is formed of a polymeric blend of the aliphatic polyketone material and a second thermoplastic polymeric material.

17. An intraluminal balloon catheter, comprising a) an elongated shaft having a proximal end, a distal end, an inflation lumen extending within at least a portion of a distal shaft section to a location spaced proximally from the distal end; and b) a balloon on the distal shaft section having an interior in fluid communication with the inflation lumen, and being formed at least in part of an aliphatic polyketone material.

18. The intraluminal catheter of claim 17, wherein the elongated shaft comprises an outer tubular member, and an inner tubular member having a lumen and being disposed within the outer tubular member and defining therewith the inflation lumen.

19. The intraluminal catheter of claim 17 further including a stent disposed about the balloon.