SINGLE-LUMEN BALLOON CATHETER HAVING A DIRECTIONAL VALVE

Abstract: This invention is a single lumen balloon catheter (100) having a valve seat (124) on the distal end of the catheter, distal of the balloon (112), which may be operated by a control wire (102) having a valve plug (104) disposed on the wire. The valve seat (106) may be engaged by the valve plug (104) from either direction, depending on the installation of the control wire (102). In either event, if the valve plug (104) is installed distally of the valve seat (124) in the catheter lumen, the valve (106) is closed by pulling on the control wire (102) (or moving the control wire (102) in a proximal direction) and introducing fluid through the catheter lumen through the balloon (112). Alternatively, the guide wire (102), with its integral valve plug (104) may be introduced from the proximal end of the catheter (100) and may traverse the body of the balloon (112) to engage the valve seat (122) in the distal end of the catheter (100). Pushing on the control wire (102) will seat the valve, allowing fluid to inflate the balloon (112).

Description: SINGLE-LUMEN BALLOON CATHETER HAVING A DIRECTIONAL VALVE FIELD OF THE INVENTION This invention is a single-lumen balloon catheter having a valve seat on the distal end of the catheter, distal of the balloon, which may be operated by a control wire having a valve plug disposed on the wire. The valve seat may be engaged by the valve plug from either direction, depending on the installation of the control wire. In either event, if the valve plug is installed distally of the valve seat in the catheter lumen, the valve is closed by pulling on the control wire (or moving the control wire in a proximal direction) and introducing fluid through the catheter lumen through the balloon. Alternatively, the guidewire, with its integral valve plug, may be introduced from the proximal end of the catheter and may traverse the body of the balloon to engage the valve seat in the distal end of the catheter. Pushing on the control wire will seat the valve, allowing the introduction of fluid through the catheter lumen to inflate the balloon. The latter arrangement allows the control wire to be interchanged with other guidewires a physician may wish to use. The balloon provided for in this invention is of a single length and does not change its axial length as it is inflated. BACKGROUND OF THE INVENTION Angioplasty is an excellent method for treating a wide variety of vascular diseases. In particular, it has been used extensively for opening stenoses in coronary arteries. The process has been increasingly used for treatment of stenosis in other parts of the vascular system. One of the more well known and widely practiced forms of angioplasty makes use of a dilatation catheter which has an inflatable balloon at is distal end. Using fluoroscopy, the physician guides the catheter through the vascular system until the balloon is properly positioned. By applying a fluid through the separate inflation lumen, the balloon is inflated. The balloon's inflation causes the artery to stretch and presses the lesion or stenose into the artery wall, thereby re¬ establishing after deflation of the balloon, increased blood flow through the artery. In order to treat very tight stenoses, i.e.,. those having small openings, increasingly small catheter diameters are desirable. Significantly more flexible catheters are also desired in that otherwise very tight areas of stenosis will not be approachable. Although flexible and narrow of diameter, a good catheter must also be easily introduced and easily advanced through the tortuous path of the vascular system. There are a variety of dilatation catheter types. Many use multiple lumens. For instance, a catheter may use a separate guidewire lumen so that a guidewire can be used to establish the path to the stenosis. The catheter may then be fed over the guidewire until the balloon is positioned over the stenosis. The catheter obviously has a separate lumen to allow introduction of and removal of fluid for the balloon. Other catheter designs include those which act as their own guidewire, thereby eliminating the need for a separate guidewire lumen. Elimination of the need for the separate lumen means that the profile of the catheter can be somewhat smaller. Typical of such integral designs are U.S. Patent 4,606,247, to Fogarty et al., which shows a catheter having an evertible balloon at is distal tip. The distal tip of the catheter is placed near the stenosis to be treated. The balloon is extended beyond the distal tip to a position within the stenosis and then inflated to press the lesion back into the wall of the vessel. The balloon contains a passageway in the middle having a plug of some elastomeric material through which a guidewire may be placed. The plug retains the pressure of the fluid on the balloon, whether the guidewire is present or not. Another "over-the-wire" catheter is shown in U.S. Patent 5,085,636, to Burns. The Burns device utilizes a balloon having a port for introducing fluid into the balloon and simultaneous device for not allowing fluid to pass through the catheter when a guidewire is present in the vicinity of the balloon. The fluid seal is distendible and does not allow fluid past the guidewire. My U.S. Patent Application Serial No. 07/650,808, filed February 5, 1991 entitled "Single Lumen Low Profile Valved Balloon Catheter" discloses a single lumen balloon catheter having a catheter using a flexible guidewire which extends axially through the lumen beyond the open end of an intermediate balloon segment. The guidewire is axially movable within the lumen and has two discrete portions of different diameters. The first diameter, distal on the guidewire, is smaller that a second more proximal diameter on the guidewire. The larger guidewire meshes with the diameter of the lumen just proximal of the balloon thereby sealing it on the proximal end. Simultaneously at the distal end of the balloon a valve member mounted on the guidewire blocks the distal opening of the catheter. None of the prior art shows a device in which a control wire having a valve plug mounted thereon, which meshes with a valve seat mounted within the lumen and in which the balloon maintains a constant axial length during its distension. SUMMARY OF THE INVENTION This invention is a single lumen valved balloon catheter assembly with a single lumen having a proximal end, an open distal end, a valve seat section located towards the distal end of the catheter having both distal and proximal valve surfaces. The catheter body has a balloon section proximal of the valve section having an inflatable balloon. The balloon segment or section includes therein a balloon inner member, the interior of which is generally colinear with the lumen in the catheter body, and which balloon inner member allows fluid communication between the catheter lumen and the interior of the balloon. The invention also includes a flexible guidewire extending axially through the lumen beyond the open end, the guidewire being axially movable within the lumen and having a valve plug disposed near the distal end of the guidewire. The valve plug is of such a size and configuration that is able to close the lumen to fluid flow upon engagement with either the proximal or distal surface of the valve seat. The guidewire and its valve seat are produced in such a fashion that the guidewire may be introduced into the catheter lumen from the distal end thereby allowing the valve plug to contact the distal valve seat or the guidewire may be installed from the proximal end thereby allowing the valve plug to contact the proximal valve surface. Optional, but very desirable, is a catheter body section proximal of the balloon section which is sufficiently stiff to permit use of the guidewire-valve plug in sealing the valve. Preferably, the catheter body section is a multilayered, polymeric tubing that does not kink, "accordion", or stretch upon application of axial force on the guidewire. The most preferred combination of materials is a slippery material as the inner surface of the section surrounded by a high performance engineering polymer such as polyimide. The catheter may be of a very small diameter or low profile and consequently is quite flexible in its operation. The balloon inner member may be any of a number of devices allowing fluid communication between the catheter lumen and the interior of the balloon. For instance, the balloon inner member may be a coil, a braid, a braid or coil supported by a tube having holes through its wall, or a tube having holes through its wall. BRIEF DESCRIPTION OF THE DRAWINGS Figures 1A and IB are partial, enlarged, semi- cross sectional depictions of the distal portion of the catheter made according to this invention. Figure 2 shows a close up side view of the distal portion of a guidewire suitable for use in this invention. Figures 3A and 3B show side views of two variations of the balloon inner member. Figures 3C and 3D show enlarged partial cross- sections of still further variations of the balloon inner member. DESCRIPTION OF THE INVENTION Figures 1A and IB show the distal portion, generally designated (100) , of a catheter assembly made according to one embodiment of the invention. Figure 1A depicts the distal end of the catheter assembly when the guidewire has been inserted with the valve plug (104) distally of the valve section (106) . Figure IB shows the same catheter assembly (100) with the guidewire (102) with a valve plug (104) positioned proximally of the valve region (106) . Referring to Figure 1A, the catheter body generally is made up of an outer, thinwall tubing (108) and an inner tubing (110) . The balloon body (112) , having the balloon inner member (114) , which balloon inner member 114 is made up of balloon inner member end sections (116) and a fluid permeable member (118) . Distally of balloon (112) is located the valving for the catheter. The valving is a valve section (106) which may be made up of a simple tube having a metal band (120) located so as to form a valve surface (122) proximally of the metal band (12) on the interior of the lumen and a valve surface (124) distally of the band (120) . The catheter (100) has a body section (109) proximal of the balloon section which desirably is made up of an outer tubing (108) which is strong and flexible and an inner tubing member (110) . Although there are a number of materials which are suitable for service as the outer tubing, e.g., high density polyethylene (HDPE) , low density polyethylene (LDPE) , certain highly cross linked silicones, polyesters (including Nylon) , polyvinyl chloride, high molecular weight polyurethanes, and various polyimides. Of those materials, a polyimide is the most desirable in that it has a substantial axial strength and is therefore quite "pushable" but also maintains the catheter lumen open even under the severest of pressure. The distal portion of this catheter body is preferably of a much more flexible material such as low density polyethylene. The inner tubing member (110) is not a required portion of the inventive device but is desirable. The member (110) may be coextruded with the outer tubing (108) or may be a discrete member. Suitably lubricious materials include polysulfides and polyfluoroethylenes. Suitable polyfluoroethylenes include polytetrafluoroethylene, fluoroethylene copolymers having perfluoroalkoxy groups, copolymers of tetrafluoroethylene, hexafluoropropylene, and copolymers of ethylene and tetrafluoroethylene. Most preferred are copolymers of tetrafluoroethylene and hexafluoroethylene. Although the balloon (112) may be made out of a variety of materials, I have found that the balloon is readily formed from a length of radiation-hardened polyolefin tubing. The chosen polyolefin may be low density polyethylene, high density polyethylene, polypropylene, polybutene, or interpolymers or mixtures of these polymers. In any event, a balloon may be formed by closing one end and applying about 20 to 45 pounds per square inch of pressure within the tube and heating the portion which is to form the balloon to a temperature of between 300-350°F. Obviously, the length of the balloon formed is determined by the length of the tubing heated. After the balloon is produced in an appropriate size, the heat is removed, and the balloon is allowed to cool. The ends may be cut so to fit in the catheter assembly. Typically the balloon is squeezed to a size near that of the catheter lumen. The ratio of the collapsed diameter of the balloon to the diameter of the catheter just proximal of the balloon is no more than about 1.2 to 1 and preferably no more than about 1.1 to 1. The production of the balloon in this fashion results in a device in which the diameter of the balloon before inflation as compared to the diameter of the balloon after inflation may be about 1:6 or less. The balloon made in this fashion is also axially very certain in size. Unlike elastomeric balloons which may vary in length when inflated, this balloon is essentially isoaxial, particularly when the balloon inner members described herein are utilized. The balloon inner member assembly (114) shown in Figures 1A and IB has two ends (116) and a coil spring (118) . This construction will be described in more detail below. Finally, the valve portion of the catheter assembly is preferably inserted into the portion of the balloon having relatively constant inner diameter. It is held in place by heat welding or gluing or other suitable process. The valve region (106) with its ring (120) and proximal valve surface (122) and distal valve surface (124) may be made by the following procedure. Other procedures are certainly acceptable but I have found that the following procedure produces an excellent result. A polymeric tube having an inside diameter larger than the guidewire is stretched over a mandrel such as a suitably sized stainless steel wire. The ends are locked over the mandrel by heating. A temperature of about 600°F to appropriate when the chosen polymer is a polyimide. A ring having an appropriate inside diameter is slipped over the tubing. The locked ends of the tubing are cut off to allow the tubing to recover its original dimensions. Polyimide tubing recovers fully by heating it to about 550°F. The ring may be of gold, platinum, platinum-tungsten alloy, stainless steel, or other suitable and, preferably, radioopaque materials. The tubing, upon return to its former diameter, forms distal and proximal surfaces adjacent the ring which serve as valve surfaces for the plug residing on the guidewire. This distal structure substantially eliminates the possibility of "accordioning" when the distal valve surface (124) is used as the valve seat. Figure IB simply shows the insertion of the guidewire (102) from the proximal end of the catheter so to allow the valve plug (104) to seat against the proximal valve surface (122) . In this instance the valve is seated by pushing the guidewire (102) distally prior to filling the balloon (112) with a fluid via the catheter lumen. Some clinical situations require that the balloon catheter be used in conjunction with a specific or preferred guidewire to gain access to the vascular anatomy. Some clinical situations also require that site-specific drugs such as urokinase for clot dissolution or contrast materials for fluoroscopic imaging be delivered through the catheter before a balloon angioplasty is performed. During such clinical situations, the inventive catheter may be used in conjunction with any guidewire of compatible size to gain access to the vascular anatomy. The catheter may be used as an infusion catheter if so desired. If a balloon angioplasty is then desired, the guidewire are removed and the inventive guidewire (102) having the valve plug is introduced at the proximal end of the catheter, engaged with the valve surface (122) in valve region (106) , and the balloon inflated. This procedure of not replacing the infusion catheter by a balloon catheter and of merely substituting guidewires is quite efficient and is desirable in procedures such as cerebral angioplasty where time is a critical element. The guidewires (112) used in these devices are straightforward. The shape of the valve plug (104) is relatively unimportant so long as it meshes adequately with the valve surfaces formed in valve region (106) . I have found that a spherical surface is adequate and desirable. Moreover, in addition to the relatively simple guidewires of varying thicknesses as are known in this technology and shown in Figures 1A and IB, the guidewire used in this invention may additionally have a flexible tip (202) as in shown in Figure 2. These flexible tips are well known. They are used with the aid of fluoroscopy to advance the catheter through the vasculature. The body of the catheter (with the collapsed balloon) is moved distally along the guidewire to a site where the guidewire may be again introduced farther into the vasculature until a desired site is attained. Obviously, use of the guidewire in this fashion typically requires that the guidewire be introduced into the catheter body from the distal end rather than from the proximal end. Figures 3A through 3D show a variety of balloon inner members which help to provide axial length stability to the balloon (112) shown in Figures 1A and IB and maintain the lumen within the valve region in general colinear relationship with the lumen of the more proximal portions of the catheter assembly. Figure 3A shows a simple balloon inner member (114) as was included in the devices shown in Figures 1A and IB. Balloon inner member (114) is made up of two ends (116) and a spring (118) . The ends serve to allow mounting of the balloon inner member (114) in the sections of the catheter having reasonably constant diameter. The inner diameter may be large enough to pass the valve plug (104) therethrough or may be smaller to allow only the guidewire to pass. The ends have, of course, a lumen allowing a guidewire to pass completely through the ends and through the intermediate coil (118) . The ends (116) may be attached to the coil (118) by any suitable means including gluing, shrink wrapping, heat welding, solvent welding, and a host of other ways. The spring (118) involved is one having an inside diameter at least larger than that of the guidewire passing through it. Typically the inside diameter of coil (118) would be 0.020 to 0.035 of an inch. The diameter of coil wire typically would be in the region of 0.003 to 0.005 of an inch. The coil itself (118) may be wound in such a way that there is little space between windings. Ideally, the windings are flush with each other. That is to say the pitch of the coil is equal to the diameter of the wire making up the coil. The coil may be of any suitable material although gold alloys, silver alloys, platinum alloys, and other biocompatible materials having significant springiness are appropriate in this service. Polymeric materials or carbon fiber materials having the appropriate physical characteristics are also quite workable. Figure 3B shows braided balloon inner member in which a braid (304) is substituted for the spring or coil (118) shown in Figure 3A. The materials of construction and size of the wire or ribbon making up the braid are quite similar to the coil (118) shown in 3A. Figure 3C shows a device similar to that shown in Figure 3A, in that a coil is used to permit the flow of fluid from the lumen inside the balloon inner member (306) into the body of the balloon, as is shown in Figure 1A or IB. In this instance, the balloon inner member (306) additionally contains an interior tubing (308) coaxial to the coil (310) . The inner tubing (308) has a number of orifices (312) to permit fluid flow. The inner member (308) may be of metal, polymer, carbon or other suitable biocompatible material. Desirably the tubing is a polymeric material such as a polyimide, which is stiff, strong, and biocompatible. The ends of the inner tubing (308) adhere to the respective ends. Figure 3C is a partial cutaway showing both the interior and the exterior of the balloon inner member (306) . Figure 3D shows a partial cutaway of a balloon inner member (314) which is analogous to that shown in Figure 3C, except that instead of coil (310) , the exterior of the inner tubing (308) is a braided material (316) . The coil of Figure 3C and the braid of Figure 3D are optional. The catheter assembly of the invention is operated in similar fashion to other valve balloon catheters. In such operation, the guidewire is advanced into the vasculature to a desired site, and the catheter body is tracked over the guidewire. The location of the guidewire and the balloon within the vessel may be . determined by conventional radiology techniques. Once the balloon is at the desired site within the vessel, the catheter lumen is flushed by injecting fluid through the catheter lumen, the valve plug (104) is seated against the distal valve surface (124) or the proximal valve surface (122), depending upon the end from which the guidewire was introduced, by axially manipulating the guidewire. The valve plug (104) blocks the distal opening of the catheter tube. The balloon is then inflated by injecting fluid through the catheter lumen. If desired, controlled distal leakage of the fluid from the catheter tip may be achieved by a slight adjustment in the tightness of the seating between valve plug (104) and the respective valve seating areas. The balloon may be deflated by withdrawing fluid from the catheter lumen. Many alterations and modifications may be made by those of ordinary skill in the art without departing from the spirit and scope of this invention. The illustrated embodiments have been shown only for purposes of clarity. The examples should not be taken as limiting the invention as defined by the following claims, which claims include all equivalents, whether those equivalents are now or later devised.

Claims: I CLAIM AS MY INVENTION: 1. A single-lumen balloon catheter assembly comprising a catheter body having proximal and distal ends, a single lumen extending between those proximal and distal ends, an inflatable balloon having proximal and distal ends disposed in the distal region of the catheter body, a valve seat disposed between the distal end of the inflatable balloon and the distal end of the catheter body, which valve seat is formed by a circumferential band cinching a portion of the catheter body forming distal and proximal valve surfaces, and allows passage of a control wire therethrough, and is adapted to engage and seal said lumen, both on its distal and proximal valve surfaces, with a valve plug disposed on a control wire. 2. The catheter assembly of claim 1 also comprising a control wire having distal and proximal ends, having a valve plug disposed near its distal end adapted to engage and seal said lumen by contacting either the distal or proximal valve surfaces by sliding axially through the catheter lumen, and adapted to be introduced into the catheter body either through the proximal or distal ends. 3. The catheter of claim 2 wherein the control wire is a guidewire having a proximal end and a distal tip. 4. The catheter of claim 3 wherein the guidewire additionally comprises a bendable guide tip at its distal tip. 5. The catheter of claim 2 wherein the inflatable balloon additionally comprises a balloon inner member allowing fluid communication between the lumen and the inflatable balloon and extending between the distal an proximal ends of the balloon, and adapted to allow axial passage of the control wire. 6. The catheter of claim 5 wherein the balloon inner member is additionally adapted to allow axial passage of the valve plug. 7. The catheter of claims 5 or 6 wherein the balloon inner member comprises a coil. 8. The catheter of claims 5 or 6 wherein the balloon inner member comprises perforated tubing. 9. The catheter of claim 8 wherein the balloon inner member additionally comprises a coil coaxially disposed about the perforated tubing. 10. The catheter of claims 5 or 6 wherein the balloon inner member comprises a braided or woven tubing. 11. The catheter of claim 8 wherein the balloon inner member additionally comprises a braided or woven tubing coaxially disposed about the perforated tubing. 12. The catheter of claim 2 wherein the ratio of the diameter of the balloon before inflation and the diameter of the balloon after inflation is less than 1:6. 13. The catheter of claim 2 wherein the diameter of the balloon before inflation is within 10% of the diameter of the catheter body proximal of the inflatable balloon. 14. The catheter of claim 2 wherein the circumferential band is radiopaque. 15. The catheter of claim 2 wherein the valve plug is spherical. 16. The catheter of claim 2 wherein the catheter body comprises a polyimide tubing coaxially surrounding a lubricious polymeric layer. 17. The catheter of claim 16 wherein the lubricious polymeric layer comprises a fluoroethylene polymer. 18. The catheter of claim 17 wherein the fluoroethylene polymer is selected from polytetrafluoroethylene, fluoroethylene copolymers having perfluoroalkoxy groups, copolymers of tetrafluoroethylene and hexafluoropropylene, and copolymers of ethylene and tetrafluoroethylene. 19. The catheter of claim 18 wherein the fluoroethylene polymer is a copolymer of tetrafluoroethylene and hexafluoropropylene.

Inventors: SAMSON GENE, SAMSON, GENE
Applicants: SAMSON GENE, TARGET THERAPEUTICS INC, SAMSON, GENE, TARGET THERAPEUTICS, INC.
Application year: 1993
Main classification: A61M25
IPC codes: A61M25, A61M29, A61M39