Patent Application
20070129748
The present invention relates to the field of catheter assemblies, more particularly, balloon catheters.
Balloon catheters, having expandable balloon members located at the distal end of the balloon catheter, are employed in a variety of medical procedures including as dilatation devices for compressing atherosclerotic plaque which results in a narrowing of the arterial lining, and for delivery and expansion of prosthetic devices such as stents, to a lesion site, i.e. vessel obstruction, within a body vessel.
One medical procedure where balloon catheters are employed is percutaneous transluminal coronary angioplasty, or balloon angioplasty, which is a minimally invasive, non-surgical means of treating peripheral and coronary arteries. This technique consists of inserting an uninflated balloon catheter into the affected artery. Dilation of the diseased segment of artery is accomplished by inflating the balloon which pushes the atherosclerotic lesion outward, thereby enlarging the arterial diameter. Angioplasty has become recognized as an efficient and effective method of opening stenoses in the vascular system. In the most widely used form of angioplasty, a balloon catheter is guided through the vascular system until the balloon, which is carried at the distal end of a catheter shaft, and which may carry an expandable stent, is positioned across the stenosis or lesion, i.e., vessel obstruction. The balloon is then inflated to apply pressure to the obstruction which is essentially remolded by pressing it against the inner wall of the vessel whereby the vessel is opened for improved flow. Due the expansion of the balloon, the stent, which is situated on the balloon, is also expanded and released to aid in support and/or repair of the vessel wall.
A stent is typically crimped onto the balloon while the balloon is in a folded/wrapped configuration. Once the site of deployment has been reached, the balloon is inflated, thereby expanding the stent. The balloon is then deflated wherein it rewraps and is then removed from the body vessel.
One feature which may be desirable to facilitate advancement of the catheter assembly through the body vessel, is to impart lubriciousness to the catheter surfaces, including to the expandable balloon member. One method of achieving this has been to apply a lubricious coating to the exterior surface of the balloon.
Increasing the lubriciousness of the balloon surface can also facilitate withdrawal of the balloon from a deployed, expanded stent.
One problem that can occur when an expandable balloon member with a lubricious surface is employed for delivery of a stent, however, is that during insertion, delivery through the vessel, and deployment of the stent at the lesion site, the stent may slip off of the balloon due to the lubricity of the surface. Such unplanned movement can negatively impact the ability to correctly position the stent at the lesion site.
There remains a need in the art for an expandable medical balloon having a lubricious surface which has minimal negative impact on securement of an intraluminal medical device to the expandable balloon member, but which facilitates balloon withdrawal after deployment of an intraluminal medical device.
All US patents and applications and all other published documents mentioned anywhere in this application are incorporated herein by reference in their entirety.
Without limiting the scope of the invention a brief summary of some of the claimed embodiments of the invention is set forth below. Additional details of the summarized embodiments of the invention and/or additional embodiments of the invention may be found in the Detailed Description of the Invention below.
A brief abstract of the technical disclosure in the specification is provided as well only for the purposes of complying with 37 C.F.R. 1.72. The abstract is not intended to be used for interpreting the scope of the claims.
In one aspect, the present invention relates to a predetermined strategic arrangement of differentially lubricious surfaces on a balloon catheter, particularly on an expandable balloon member of a catheter delivery device. The strategic arrangement of lubricious surfaces can facilitate balloon withdrawal after deployment of a medical device, but may have little if any negative impact on securement of the medical device to the expandable balloon member during delivery of the device through a body vessel. Furthermore, the strategic placement of the lubricious coating can prevent unexpected movement of the intraluminal medical device on the expandable balloon member during delivery.
In one embodiment, the balloon is selectively treated to impart lubricity by imparting lubricity to the surface in those areas between the folds of the balloon, such that the treated areas are not in contact with the crimped stent until deployment. Upon deflation of the balloon, the lubricious area, or a portion thereof, remains exposed on the outside of the collapsed balloon.
The invention thereby facilitates insertion into a vessel and withdrawal of the expandable balloon member from the stent after the stent has been deployed and expanded. The strategic arrangement of lubricious surfaces decreases the likelihood that the stent will slip from the balloon surface.
These and other aspects, embodiments and advantages of the present invention will be apparent to those of ordinary skill in the art upon review of the Detailed Description and Claims to follow.
a is a radial cross-section view of a balloon similar to that shown in
b is a radial cross-section view of a balloon similar to that shown in
a is a radial cross-sectional view of a balloon similar to that shown in
b is a radial cross-sectional view of a balloon similar to that shown if
c is a radial cross-sectional representation of a balloon similar to that shown in
While this invention may be embodied in many different forms, there are described in detail herein specific embodiments of the invention. This description is an exemplification of the principles of the invention and is not intended to limit the invention to the particular embodiments illustrated.
All published documents, including all US patent documents, mentioned anywhere in this application are hereby expressly incorporated herein by reference in their entirety. Any copending patent applications, mentioned anywhere in this application are also hereby expressly incorporated herein by reference in their entirety.
For the purposes of this disclosure, like reference numerals in the figures shall refer to like features unless otherwise indicated.
Depicted in the figures are various aspects of the invention. Elements depicted in one figure may be combined with, or substituted for, elements depicted in another figure as desired.
The medical balloons described herein, have a first deflated state in which the balloon has at least two folded wings. Due to the folding, the balloon surface area can be divided in an outer exposed surface and a complementary inner surface which is unexposed. The unexposed surface includes the inner surface of the folded wing, as well as the unfolded area of the balloon which does not form the wing, and which is also covered by the folded wing. The totality of the unexposed surface, including both wing and non-wing areas, shall be referred to herein, as the inner surface.
The inner surface includes a lubricious surface treatment. This configuration is suitable for medical device delivery wherein it is desired that the medical device come into contact with the outer surface of the wings, but not with the inner surface. The balloons further have an expanded state.
Turning now to the figures,
Balloon 20, as shown in radial cross-section, taken at section 2 in
a is a radial cross-section of balloon 10 similar to that shown in
b is a radial cross-sectional view of balloon 10 similar to that shown in
Furthermore, it is possible for the lubricious coating to migrate or smear wherein the coating is transferred to the originally non-coated areas on the balloon surface during expansion and/or deflation resulting.
After expansion of the balloon and stent, portions of the expanded balloon surface beneath the stent will be covered by the lubricious coating thereby decreasing the resistance during withdrawal of the catheter assembly after expansion and deployment of the stent.
Once the stent has been deployed, the balloon may be deflated by application of negative pressure. Deflation of the balloon after inflation permits reformation of wings or flaps which can become wrapped around the catheter shaft for further advancement of the catheter to treat another lesion, or withdrawal of the catheter from the patient. However, the balloon may not return to the exact same deflated configuration that it had prior to expansion. Consequently, the lubriciously treated surfaces may be at least partially exposed in the deflated state which occurs after balloon expansion.
The balloons according to the invention may be formed using any suitable balloon forming techniques. One method is to extrude a tube of polymer material, placing the extruded tube of polymer material in a mold form, and radially expanding the tube under pressure and with heat if required to soften the polymer material such that the mold form is filled and the polymer material takes on the shape of the mold form. Upon removal of the balloon from the mold form, the balloon is said to be in its static state. Such techniques are disclosed in U.S. Pat. No. 4,490,421, the entire content of which is incorporated by reference herein. The tube may also be axially stretched with positive pressure. Radial expansion caused by the positive pressure on the tube interior with axial stretching establishes biaxial stretching of the tube. The biaxial stretching is maintained until the tube assumes the shape of the mold.
In accordance with the present invention, a deflated dilatation balloon can be prepared for insertion through a patient's body vessel, such as through the cardiovascular system, by a series of steps to create folded wings or flaps. The wings may be wrapped circumferentially to provide a minimized outer diameter when the balloon is in its deflated state. This type of procedure is disclosed in commonly assigned U.S. Pat. No. 5,342,307, the entire content of which is incorporated by reference herein.
In one embodiment described therein, the wings are formed by initially pressurizing the balloon to a low pressure and centering it within tubular fixture. Movable blades which are initially in a retracted position can be simultaneously moved radially inward toward the longitudinal axis of the balloon. A vacuum is pulled through an inflation lumen to cause formation of wings. While the vacuum is maintained, the blades are returned to their retracted position and the balloon is removed from fixture. Once the winged configuration has been formed, the balloon may be heat set. Other embodiments of wing formation are also disclosed in U.S. Pat. No. 5,342,307.
U.S. Pat. No. 5,318,587, the entire content of which is incorporated by reference herein, describes another procedure of pleating and folding expandable medical balloons. The wings may also be folded such as to form an accordion like structure.
In the expanded state, balloon 10 takes on a cylindrical configuration, which may be similar to that shown in
Lubricity may be imparted to the surface of the medical device using any suitable method known in the art. This can be accomplished by coating the surface with a lubricious coating. Methods of coating include, but are not limited to, pad printing, sponge coating, brushing, painting, sputtering, spraying, etc.
Lubricious coatings are known in the art. Any suitable lubricious hydrophobic and/or hydrophilic material may be employed in the lubricious coating in order to impart lubriciousness to the surface of the expandable balloon, as well as combinations thereof.
Examples of suitable lubricious hydrophobic materials include, but are not limited to, silicone and fluoropolymers such as polytetrafluoroethylene. These materials may be employed alone, or in combination with other materials.
Suitable hydrophilic materials include, but are not limited to, polyalkylene oxides such as polyethylene oxide, carboxylic acids such as homopolymers and copolymers of (meth) acrylic acid including polyacrylic acid homopolymer, copolymers of methylvinyl ether and maleic acid, poly(vinylpyrrolidone), poly (sodium-4-styrenesulfonate), poly(3-hydroxybutyric acid), poly(N-alkylacrylamide), poly(vinyl alcohol), poly(ethyleneimine), polyamides, methyl cellulose, carboxymethylcellulose, polyvinylsulfonic acid, heparin, dextran, modified dextran, chondroitin sulphate, lecithin, etc., and mixtures thereof. Many of these materials are referred to in the art as hydrogel polymers.
Hydrophilic polyurethanes may be employed herein. Hydrophilic polyurethanes such as polyether polyurethanes and particularly aliphatic polyether polyurethanes may be employed herein. Hydrophilic polyurethanes are typically formed with relatively higher amounts of polyethylene oxide or polyethylene glycol. Examples of suitable hydrophilic polyurethanes are those available from Thermedics, Inc. under the tradename of TECOPHILIC®.
Examples of suitable hydrophilic lubricious polymer materials which may be employed herein are disclosed in commonly assigned U.S. Pat. Nos. 5,509,899, the entire content of each of which is incorporated by reference herein.
Interpenetrating networks (IPNs) which include hydrogel polymers may be employed herein. Such IPNs may be formed using at least one crosslinkable material and a hydrogel polymer. Suitable IPNs are disclosed in commonly assigned U.S. Pat. No. 5,693,034, the entire content of which is incorporated by reference herein.
Suitable crosslinkable materials include ethylenically unsaturated resins such as mono-, di- or tri-(meth)acrylates and mixtures thereof. Suitable crosslinkers of this type are found in commonly assigned copending U.S. Patent Publication US20050054744 filed Sep. 9, 2003, the entire content of which is incorporated by reference herein.
One suitable example of such an IPN is one including a vinyl polymer and an uncrosslinked hydrogel, in particular where polyethylene oxide (PEO) is employed as the hydrogel and the vinyl polymer is neopentyl glycol diacrylate (NPG).
A specific example is PEO hydrogel and neopentyl glycol diacrylate at a ratio of about 10:1 dissolved in a cosolvent blend of alcohol and water at a ration of 4:1 alcohol to water. A photoinitiator such as azobis-isibutironitrile photoinitiato can be added in minimal amounts effective to initiate NPG polymerization. Photoinitiators are known to those of skill in the art. Examples of lubricious hydrogels of this type are disclosed in commonly assigned U.S. Pat. No. 5,693,034, the entire content of which is incorporated by reference herein.
Another examples is PEO and ethoxylated trimethylol propane triacrylate at a ration of about 10:1, with a silane coupling agent, an acrylic flow modifier, and a small amount of a photoinitiator in a cosolvent blend of isopropyl alcohol and water at a ratio of about 4:1. This type of lubricant is disclosed in commonly assigned copending U.S. patent application Ser. No. 20050170071, the entire content of which is incorporated by reference herein in its entirety.
Another example of a suitable IPN is one using a blend of neopentyl glycol diacrylate or polyethylene glycol diacrylate and at least one hydrophilic aliphatic polyether polyurethane such as polyether polyurethanes available from Thermedics, Inc. under the tradename TECOGEL® including TECOGEL® 500 and TECOGEL® 2000.
Such IPNs are disclosed in commonly assigned copending U.S. Patent Publication Nos. US20050054774, incorporated by reference above, and US20050055044, filed Sep. 9, 2003, which is incorporated by reference herein in its entirety.
Other IPNs including hydrogels are disclosed in commonly assigned U.S. Pat. Nos. 6,265,016; 6,120,904; 6,080,488; 6,040,058; 6,030,656; 6,017,577; 5,919,570; 5,849,368; 5,662,960 and 5,576,072, each of which is incorporated by reference herein in its entirety.
Another example of compositions which form hydrogels in aqueous environments when crosslinked are those disclosed in commonly assigned U.S. Pat. Nos. 6,660,827; 6,534,560; 6,403,758 and 6,316,522, each of which is incorporated by reference herein in its entirety. These are covalently crosslinkable copolymers having a bioresorbable region, a hydrophilic region and at least two crosslinkable functional groups per polymer chain.
Plasma treatment can also be employed to modify polymer coatings to impart lubriciousness, or by plasma deposition of lubricious coatings on the device surface.
For example, plasma treatment can be used to strategically fluorinate the surface of the device thereby imparting lubriciousness only in predetermined specific locations on the balloon surface. This type of surface treatment is disclosed in commonly assigned, copending U.S. patent Application Ser. No. 11/005734, filed Dec. 7, 2004, the entire content of which is incorporated by reference herein in its entirety.
Another method of imparting lubriciousness to the surface of the medical device is to use a fluorinated sol-gel derived ceramic such as that disclosed in commonly assigned copending U.S. Patent Application Attorney Docket No. S63.2-11846US01, the entire content of which is incorporated by reference herein in its entirety.
The lubricious surface treatment may be applied to the balloon at any stage during the balloon forming process, including during extrusion, by selectively co-extruding a lubricious coating onto the tubular extrudate, for example.
The lubricious surface treatment may also be applied to the balloon after wing formation.
The surface of wing 20 of balloon 10 has been treated to impart lubriciousness such that when the balloon is folded as illustrated in
The present invention provides an expandable medical balloon which when deflated and a stent mounted thereon, has selectively disposed lubricious surface treatment on the surface of the expandable medical balloon such that the stent has a reduced tendency to slip during delivery through a patient's body vessel to the site of deployment the stent. The balloon may then be expanded causing the stent to expand. Negative pressure may then be applied to the balloon causing it again to deflate into a second deflated configuration, different than the first. In the second deflated configuration, the lubricious surface treatment is exposed on the outer surface such that withdrawal of the deflated balloon from the stent is readily conducted, with little resistance.
The above disclosure is intended to be illustrative and not exhaustive. This description will suggest many variations and alternatives to one of ordinary skill in this art. All these alternatives and variations are intended to be included within the scope of the attached claims. Those familiar with the art may recognize other equivalents to the specific embodiments described herein which equivalents are also intended to be encompassed by the claims attached hereto.
