US20020032359A1

Movatterモバイル変換

Info

Publication number: US20020032359A1
Application number: US09/939,478
Authority: US
Inventors: Richard Geoffrion; Gholam Zadno-Azizi; Samuel Omaleki
Original assignee: Individual
Current assignee: Medtronic Vascular Inc
Priority date: 1998-02-19
Filing date: 2001-08-24
Publication date: 2002-03-14
Also published as: US6338709B1

Abstract

A radiation delivering catheter is positioned away from the walls of the vessel to be treated, e.g. at a stenosis site, so that the radiation flux impacting the walls is more uniform. In one embodiment, one or more balloons are used, and in another, one or more expandable structures. In other embodiments, a radiation source residing within a balloon is shielded from the vessel walls when the balloon is not inflated, but exposes the vessel walls to radiation when the balloon is inflated.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention[0001]

The present invention relates generally to radiation therapy catheters, and, in particular, to an apparatus and method for properly centering or otherwise positioning a radiation therapy catheter within a vascular segment at a desired treatment site.[0002]

2. Description of the Related Art[0003]

Approximately 20-30% of patients who undergo arterial intervention experience restenosis within about 6 months of the initial treatment. This often necessitates repeating the procedure, such as balloon angioplasty, stent implantation, atherectomy, or treatment with lasers, to once again clear the patient's vascular obstruction. Repeating such a procedure, or undertaking a second, different procedure, is clearly undesirable.[0004]

Although stent implantation is used to prevent restenosis, stent restenosis occurs due to neointimal proliferation, i.e. an accelerated growth of tissue at the treated site. However, endovascular radiation effectively inhibits neointimal formation. In particular, a radiation treatment may be undertaken either prior to placement of a conventional stent or through the use of a radioactive stent, i.e. a stent that is coated or impregnated with a radioactive source. The stent may be made radioactive, for example, by placing it in a cyclotron that emits radionuclides.[0005]

Radiation therapy undertaken during or after arterial intervention can be accomplished in a variety of ways, as discussed, for example, in U.S. Pat. No. 5,213,561 to Weinstein et al., U.S. Pat. No. 5,484,384 to Fearnot, and U.S. Pat. No. 5,503,613 to Weinberger. Among other radiation therapy devices, these references disclose a guidewire having a radioactive tip, a radioactive source within a balloon catheter, and a radioactive source mounted on a balloon expansible stent. Weinberger teaches that a variety of radiation sources may be used, such as pellets, a wire, or a paste.[0006]

One frequently encountered problem is the difficulty in controlling the amount of irradiation; although, a guidewire or catheter type delivery device provides greater control of exposure time than an implanted radioactive stent. Further, a stent should match the length of the vessel segment to be treated; whereas, a guidewire or catheter can be moved axially to increase the length of the vessel exposed to radiation. With a stent, there is also the possibility that the radioactive material will leach into the surrounding tissue, as well as the possibility of thrombosis forming on the stent wire as a delayed re-endotheliatization of the stent struts.[0007]

With respect to possible exposure of the clinician or patient to radioactive material, it is easier to control exposure with a guidewire or catheter device. A sleeve or the like suitable for shielding the radioactive element can be used until the element is located at the desired treatment site. A radioactive stent, on the other hand, requires handling prior to insertion into the patient, and can result in increased radiation exposure. Also, it can be even more hazardous to handle, inject, and withdraw radioactive fluid from a balloon catheter.[0008]

In previous devices, there is also the difficulty in positioning a device at the vessel segment identified for radiation therapy. U.S. Pat. No. 5,199,939 to Dake et al. attempts to address this problem by providing stiffening members within an otherwise flexible member. An axial arrangement of radioactive pellets at the distal end of the device delivers the radioactive dosage. U.S. Pat. No. 5,503,613 to Weinberger discloses a computer-controlled afterloader that accurately places the radiation delivery wire within the blind lumen, which is sealed at its distal tip. Among the inputs to the afterloader are the location of the vessel segment, the diameter of the treatment site, and the radioactive characteristics of the radioactive element.[0009]

Unless a radiation dose delivery wire is carefully centered within a blood vessel, a relatively high radiation zone is obtained at that segment of the vessel contacting or closest to the wire, and a lower radiation zone elsewhere. U.S. Pat. No. 4,998,932 to Rosen et al. and U.S. Pat. No. 5,566,221 to Smith et al. disclose the use of balloons that aid in the centering of a catheter within a vessel. A balloon must be adequately inflated so that it contacts the vessel walls without damaging tissue or rupturing. If inflating the balloon causes enlargement of the vessel at the treatment site, the increased radius diminishes the level of radiation reaching the vessel walls. For example, irradiating tissue to a depth of about 2-3 mm within the tissue is usually desirable. A change in the diameter of the vessel diminishes the accuracy of the coordinates used by an afterloader, and the radioactive material may lack the intensity required for the desired penetration. If the balloon ruptures, pieces of the balloon may be carried downstream.[0010]

Other uses of balloons in radiation delivery include a segmented balloon centering device (see Verin et al., “Intra-arterial beta irradiation prevents neointimal hyperplasia in a hypercholesterolemic rabbit restenosis model,”[0011]Circulation, vol. 92, pp. 2284-2290, 1995) and a helical balloon, which is said to provide better flow around the catheter (see R. Waksman, “Local Catheter-Based Intracoronary Radiation Therapy for Restenosis”,The American Journal of Cardiology, vol. 78, p. 24, 1996).

Thus, there is still a need for a radiation delivering catheter that can be accurately and easily centered within a vascular segment.[0012]

SUMMARY OF THE INVENTION

The present invention satisfies the need for a device that can be accurately centered within a vessel to be radioactively treated. By accurately centering a radiation catheter within the vessel, the walls of the vessel to be treated, e.g. at a site of a stenosis, are exposed to radiation flux that is more uniform than it would be if the radiation catheter were in contact with (e.g., resting on) the vessel wall.[0013]

In the present invention, various means are utilized to properly position a radiation treatment device within the vessel. In one embodiment of the present invention, one or more balloons are employed to position a radiation delivering catheter within the vessel and away from the vessel wall. In another embodiment of the invention, expandable structures are used to do the same. In yet another embodiment of the invention, a radiation source residing within a balloon is shielded from the vessel walls when the balloon is not inflated, but exposes the vessel walls to radiation when the balloon is inflated.[0014]

In one embodiment, a self-centering radiation device for treating a segment of a vessel in a patient comprises a catheter for delivering radiation, a plurality of balloons for securing the radiation catheter within the vessel (in which at least two of the balloons are independently inflatable), and a radioactive source for treating the vascular segment, in which the radioactive source is in proximity with the radiation catheter and positioned near the balloons during treatment.[0015]

In another embodiment of the invention, a radiation device for treating a segment of a vessel in a patient comprises a catheter for delivering radiation, a radioactive source in proximity with the radiation catheter, a noncompliant balloon around the radioactive source, a lumen within the radiation catheter that is in fluid communication with the noncompliant balloon to permit inflation and deflation of the noncompliant balloon, and a compliant balloon that surrounds the noncompliant balloon. The compliant balloon expands as the noncompliant balloon expands to radioactively treat the vascular segment.[0016]

In another embodiment of the invention, a radiation device for treating a segment of a vessel in a patient comprises a catheter for delivering radiation, a radioactive source in proximity with the radiation catheter, a balloon around the radioactive source, and a lumen within the radiation catheter that is in fluid communication with the balloon, permitting inflation and deflation of the balloon. The balloon has strips of material thereon that substantially shield the surroundings from unwanted radioactive exposure when the balloon is not inflated, in which the area between the strips increases as the balloon expands to more directly expose the vascular segment to radioactive treatment.[0017]

Another embodiment of the invention is a self-centering radiation device for treating a segment of a vessel that comprises a catheter for delivering radiation, at least one expandable structure for securing the radiation catheter within the vessel, and a radioactive source for treating the vascular segment, in which the radioactive source is in proximity with the radiation catheter. The expandable structures may be self-expanding and the device may further comprise one or more sheaths for expanding and compressing the expandable structures.[0018]

The invention further includes methods of treating a segment of a vessel. One method comprises inserting a catheter into the vessel, inserting a plurality of balloons into the vessel (in which at least two of the balloons are independently inflatable), inflating at least two of the independently inflatable balloons to position the catheter away from the walls of the vessel, and exposing the vascular segment to radiation treatment.[0019]

Another method of treating a segment in a vessel comprises inserting a balloon into the vessel, placing the balloon near the vascular segment to be treated, and expanding the balloon to expose the vascular segment to radiation that is located in the balloon's interior.[0020]

Yet another method of treating a segment in a vessel comprises inserting a catheter into the vessel, inserting at least one expandable structure into the vessel, expanding the structure to position the catheter away from the walls of the vessel, and treating the vascular segment by exposing it to radiation.[0021]

In the embodiments of this invention, radiation can be delivered to the stenosis site by, for example, bonding a radioactive source directly onto the radiation catheter, or by passing radioactive carriers through a lumen within the radiation catheter. For example, the radioactive carriers, which may be in the shape of cylinders or spheres, can be carried towards (or away from) the stenosis site by fluid that is forced into (or out of) the lumen.[0022]

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal cross sectional view of a radiation delivering catheter in the prior art.[0023]

FIG. 2A is a longitudinal cross sectional view of one embodiment of the present invention in which a single balloon is used which is located at the distal end.[0024]

FIG. 2B is an end cross sectional view of the embodiment of FIG. 2A.[0025]

FIG. 3 is a schematic view of an occlusion catheter apparatus for use in the method of the present invention.[0026]

FIG. 4 is a schematic cross-sectional view of a distal portion of the catheter apparatus shown in FIG. 3.[0027]

FIG. 5 shows a preferred embodiment of a syringe assembly having features in accordance with the present invention and operably coupled to an illustrative inflation adapter at a proximal portion of a balloon catheter.[0028]

FIGS. 6A and 6B show open and closed positions, respectively, of the sealing member, which is used with the balloon catheter of FIGS. 5 and 7.[0029]

FIG. 7 shows a perspective view of the balloon catheter of FIG. 5 placed within an open inflation adapter.[0030]

FIG. 8A is a longitudinal cross sectional view of an embodiment utilizing two, independently inflatable balloons.[0031]

FIG. 8B is an end cross sectional view of the embodiment of FIG. 8A.[0032]

FIGS. 9A and 9B illustrate spherical and cylindrical radiopaque carriers, respectively, within an injection lumen for delivering radiation to a stenosis site.[0033]

FIG. 9C illustrates an alternative way of delivering radiation to a stenosis site, in which the radiopaque and radioactive carriers are fastened to a wire.[0034]

FIG. 10A is a longitudinal cross sectional view of an embodiment utilizing two balloons, in which the distal balloon is tied to a guidewire and the proximal balloon to a proximal catheter.[0035]

FIG. 10B is an end cross sectional view of the embodiment of FIG. 10A.[0036]

FIG. 11A is a longitudinal cross sectional view of an embodiment utilizing a balloon placed at the stenosis site, in which a radioactive source within the balloon is exposed to the vessel as the balloon expands.[0037]

FIG. 11B is an end cross sectional view of the embodiment of FIG. 11A.[0038]

FIG. 12 is end cross sectional view of an embodiment similar to that of FIG. 11A and 11B, in which an inner balloon is inflated to expand an outer balloon.[0039]

FIG. 13A is a longitudinal cross sectional view of an embodiment in which an expandable structure (a braid) is used to center a radiation catheter within a vessel to be treated.[0040]

FIG. 13B is an end cross sectional view of the embodiment of FIG. 13A.[0041]

FIGS. 14A and 14B show longitudinal and end perspective views, respectively, of a locking mechanism used with a wire that deploys an expandable structure (in this case, a braid).[0042]

FIG. 14C is a perspective view of an alternative locking mechanism used with a wire that deploys an expandable structure.[0043]

FIG. 15 is an embodiment utilizing two expandable structures (in this case, braids), in which the expandable structures adjoin separate catheters.[0044]

FIG. 16A is an embodiment utilizing two expandable structures (in this case, braids), in which the expandable structures adjoin the same catheter.[0045]

FIG. 16B is an end cross sectional view of the embodiment of FIG. 16A.[0046]

FIG. 17 is a schematic, longitudinal cross sectional view of an embodiment in which a membrane only partially surrounds a braid used as the expandable structure.[0047]

FIGS. 18A and 18B show end views of unperforated and perforated membranes, respectively.[0048]

FIG. 19 is a schematic, longitudinal cross sectional view of an embodiment in which a braid without a membrane is used.[0049]

FIG. 20 is a schematic, longitudinal cross sectional view of an embodiment in which a filter-like mesh is used as the expandable structure.[0050]

FIG. 21 is a schematic, longitudinal cross sectional view of an embodiment in which a slotted tube is used as the expandable structure.[0051]

FIG. 22 is a perspective view of the slotted tube used in the embodiment of FIG. 21.[0052]

FIG. 23 is a schematic, longitudinal cross sectional view of an embodiment in which a coil is used as the expandable structure, and the proximal end of a membrane surrounding the coil adjoins the coil.[0053]

FIG. 24 is a schematic, longitudinal cross sectional view of an embodiment in which a coil is used as the expandable structure, and the proximal end of a membrane surrounding the coil adjoins a sheath that surrounds both first and second elongate members.[0054]

FIG. 25 is a schematic, side cross sectional view of an embodiment in which a plurality of ribbons are used as the expandable structure.[0055]

FIG. 26 is a schematic, side cross sectional view of an embodiment in which a plurality of ribs are used as the expandable structure.[0056]

FIG. 27 is an isometric view of an embodiment of the invention in which a pull wire is used to deploy a plurality of nonself-expanding ribbons surrounded by a membrane.[0057]

FIG. 28 is a side partial sectional view of the embodiment of FIG. 27 in which the ribbons are in their relaxed, undeployed position.[0058]

FIG. 29 is a side elevational view of the embodiment of FIG. 27 in which the ribbons are deployed, and the membrane contacts the vessel.[0059]

FIGS. 30A, 30B,[0060]30C, and30D show, respectively, a braid, a filter-like mesh, a slotted tube, and a plurality of coils, which can be used as alternative expandable structures in place of the ribbons in the embodiment of FIG. 27. The respective membranes are shown in partial cross section.

FIG. 31 is a longitudinal cross sectional view of an atherectomy device.[0061]

FIG. 32 is a longitudinal cross sectional view of a device that uses a laser.[0062]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 schematically shows a conventional[0063]

radiation therapy catheter

101 being used with aguidewire102 for placement within a vessel segment, in which thecatheter101 rests against oneside108 of the wall of the blood vessel. Within thecatheter101 is aradioactive source104 that is also concentrated against oneside108 of the vessel wall. That is, a zone of higher radiation exists along the line of contact, and a lower radiation zone exists along that portion of the vessel wall not in direct contact with thecatheter101.

In the preferred embodiments of the devices and methods described herein, “centering” and the like are not be narrowly construed, but include the positioning of a catheter at or near the center of a vessel segment, or otherwise positioning the catheter symmetrically or asymmetrically within the vessel segment at a desired treatment location.[0064]

Radiation Centering Embodiments Using One or More Balloons[0065]

1. Single distal balloon[0066]

FIGS. 2A and 2B, on the other hand, illustrate an embodiment of the present invention in which a catheter[0067]201 (preferably having an I.D. (inside diameter) of 0.018 to 0.042″ and an O.D. (outside diameter) of 0.035 to 0.070″, with a 100 cm long 73D Pebax™ relatively hard proximal end, and a 20 cm long 35D Pebax™ relatively soft distal end) has aradiation source210 bonded directly to its outer surface. Alternatively, radiation may be delivered through lumens in the form of radioactive fluid (e.g. a radiochemical), pellets, or wires, as discussed more fully below in connection with FIGS. 8A, 8B,9A,9B, and9C, techniques which limit exposure to medical personnel. In addition, X-ray radiation may be generated within the patient at the treatment site using a small metallic object that is tied to an electrical source.

A[0068]

catheter

221, which functions as a guidewire, is located within theradiation catheter201 has a balloon231 (the balloons herein may be elastomeric, nonelastomeric, or composite) at its distal end. Theguidewire221 permits the clinician to direct theradiation catheter201 through thevessel235. As seen more clearly in FIG. 2B, theinterior245 of theguidewire221 is preferably hollow to permit theballoon231 to be alternately inflated and deflated with contrast fluid or a saline solution. A number of guidewire technologies for guiding a device through the patient'svessel235 may be used in this and the other embodiments, such as an integral guidewire tip, a single operator guidewire, or the exchange catheter method, as is well known in the art.

When the[0069]

balloon

231 is inflated, it tends to center theradiation catheter201 so that radiation is delivered to the site of thestenosis241 with better radial symmetry. The best results are obtained when theballoon231 is located within about 4 cm of the stenosis site241 (the balloon being on the distal side of the stenosis site), so that during treatment theradiation source210 remains substantially centrally located within the vessel at thestenosis site241. Thus, the level of radiation is nearly uniform along theradiation catheter201 at thestenosis site241, i.e. the vessel segment to be treated. A movable shield catheter250 (preferably made of Nylon, Pebax™, or polyethylene, and of size 6-8 F with an I.D. of 0.060-0.090″ and an O.D. of 0.080-0.140″) may be used when thestenosis site241 is not being treated, to shield surrounding tissue and clinical personnel from being exposed to radiation. Themovable shield catheter250 preferably comprises a nontoxic heavy metal (such as gold, nitinol, or stainless steel) or a polymer.

The[0070]

stenosis site

241 is preferably accessed through a port in the patient using an introducer (not shown). Generally, theguidewire221 is inserted to locate the site of stenosis241 (or restenosis, as the case may be), and then the radiation and

shield catheters

201 and250 are slid over the guidewire to thetreatment site241. A fluoroscopic procedure may first be used to identify thestenosis site241, as is known to those skilled in the art.

Preferably, the[0071]

guidewire

221 has a circular cross section with an outside diameter (O.D.) between about 0.010″ and 0.014″, but the O.D. may be as great as 0.044″, whereas the inner diameter (I.D.) is preferably between about 0.008″ to 0.020″, and more preferably about 0.009″ for a wire having an O.D. of 0.014″. Theguidewire221 is preferably made from stainless steel, or, alternatively, an alloy of nickel and titanium known as nitinol. Theguidewire221 is preferably oflength 190 to 300 cm and includes a tip and a 35 mm platinum coil which are not shown explicitly in FIG. 2A. Other biocompatible elongate flexible tubes made of polymeric materials such as nylon, polyamide, polyimide, polyethylenes, or combinations thereof, are appropriate for use with the present invention and are described in assignee's co-pending U.S. application Ser. No. ______ (Atty Docket PERCUS.002A) filed Mar. 6, 1997 which is entitled HOLLOW MEDICAL WIRES AND METHODS OF CONSTRUCTING SAME, the entirety of which is hereby incorporated by reference.

The[0072]

balloon

231 is preferably made of a block copolymer of styrene-ethylene-butylene-styrene (SEBS) such as C-Flex (TM) available from Consolidated Polymer Technologies. More preferably, the balloon material is C-Flex (TM) resin grade R70-050-000, as described in assignee's co-pending U.S. application Ser. No. ______ (Atty Docket PERCUS.010CP1) filed ______ and entitled BALLOON CATHETER AND METHOD OF MANUFACTURE, which is hereby incorporated by reference. Alternatively, theballoon231 may comprise a conventional compliant expansion balloon made of elastomeric material, such as latex or silicone. Theballoon231 can be attached to theguidewire221 using the methods described in the application just referenced, or by a conventional method, such as heat bonding or adhesives. For example, a primer such as 7701 LOCTITE (TM) by Loctite Corporation may be used with cyanoacrylate adhesive such as LOCTITE 4011 for attaching a SEBS balloon to a nitinol tube.

The[0073]

guidewire

221 preferably includes a catheter valve such as that described in assignee's copending U.S. application Serial No. ______ (Atty Docket PERCUS.006CP1) filed ______ and entitled LOW PROFILE CATHETER VALVE AND INFLATION ADAPTOR, which is a continuation-in-part of application Ser. No. 08/812,139 filed Mar. 6, 1997, which is a continuation-in-part of application Ser. No. 08/650,464 filed May 30, 1996, the entirety of the latest CIP being incorporated by reference. As described in more detail below in connection with FIGS. 6A and 6B, this latest CIP application describes a valve comprising a moveable sealer portion positioned within an inflation lumen, in which the moveable sealer portion may be moved to a position distal of the inflation port, thereby preventing any fluid from being introduced into or withdrawn from the balloon via the inflation port. With this arrangement, theradiation catheter201 can easily slide off of and onto theguidewire221 to be positioned within thevessel235. Preferably, theradiation catheter201 is inserted into the patient after theguidewire221 has been positioned within the patient and theballoon231 has been inflated. A computer-controlled afterloader (not shown) may be used to insert theradiation catheter201 and control the duration of the radiation therapy. Parameters, such as the location of thetreatment site241 and the diameter of the vessel at that site, are obtained prior to the radiation therapy and are programmed into the afterloader, as is known to those skilled in the art. One source for an afterloader is Nucletron Corporation in Columbia, Md.

The shelf or half-life of the[0074]

radiation source

210 is important to the dosimetry of the radiation therapy. A “fresh” isotope is preferred to more accurately estimate and control the delivery of a prescribed amount of radiation to a desired tissue depth, such as 14 Gy (or more generally, 8-25 Gy, to a depth of about 2 mm).

In addition, the choice of radioactive isotope is dependent upon the diameter of the[0075]

vessel

235 and the desired treatment time. For example, a more highly radioactive source may be preferable in a larger diameter vessel, since the treatment time is preferably limited to about 5 minutes or less. Gamma(γ)-emitting sources are generally of higher radioactivity and have a greater half-life than beta(β)-emitting sources. For example, iridium 192 (¹⁹²Ir) has a half life of about 74 days and phosphorus 32 (³²P) has a half life of about 14.3 days. Other β-emitting sources, such asStrontium 90/Yttrium (⁹⁰Sr/Y),³²P or⁹⁰Y may be used. Or, a γ-emitter such as¹⁹²Ir, iodine 125 (¹²⁵I), or palladium 103 (¹⁰³Pd) may be used. It is also possible to utilize a higher intensity source such asCobalt 60, although the particular isotope used is not determinate of the benefits of the present invention.

2. A preferred catheter with integral inflatable balloon[0076]

A catheter suitable for use in the present invention (such as catheter[0077]221) is illustrated in FIGS. 3 and 4. Thecatheter apparatus110 is comprised of four communicating members including anelongated tubular member114, aninflatable balloon member116 or other expandable medium, a core-wire member120 and acoil member122. Thecatheter apparatus110 is preferably provided with an outer coating of a lubricous material, such as Teflon.

The[0078]

tubular member

114 of thecatheter apparatus110 is in the form of hypotubing and is provided with proximal and

distal ends

114A and114B as well as aninner lumen115 extending along thetubular member114. Theballoon member116 is coaxially mounted near thedistal end114B of thetubular member114 bysuitable adhesives119 at aproximal end116A and adistal end116B of theballoon member116 as shown in FIG. 4. Proximal and distal

tapered portions

123 and124 on either side of theballoon116 preferably include adhesives. Proximal and distal adhesive stops125 and126 contact theadhesives119 to define the working length of theballoon116. Aradiopaque marker127 is preferably located within the proximaltapered portion123. Anotch128 in thetubular member114 permits fluid communication between thelumen115 and theballoon116.

A core-[0079]

wire member

120 of thecatheter110 may be comprised of a flexible wire. Theflexible wire120 is preferably secured to thetubular member114 within thelumen115 by a combination of adhesives and crimps129 (FIG. 4). Theproximal end120A of theflexible wire120 can have a transverse cross sectional area substantially less than the smallest transverse cross-sectional area of theinner lumen115 of thetubular member114. Theflexible wire120 can also taper towards thedistal end120B to smaller diameters to provide greater flexibility to theflexible wire120. However, theflexible wire120 may be in the form of a solid rod, ribbon or a helical coil or wire or combinations thereof. As shown in FIG. 4, thedistal end120B of theflexible wire120 is secured to arounded plug118 of solder or braze at thedistal end122B of thecoil member122. Thecoil member122 of thecatheter110 may be comprised of a helical coil. Thecoil member122 is coaxially disposed about theflexible wire120, and is secured to theflexible wire120 by soldering or brazing. Core wires for use in a medical catheter are described in Assignee's co-pending U.S. application Serial No. ______, filed on the same day herewith (Atty. Docket No.

PERCUS.053A), entitled CORE WIRE WITH SHAPEABLE TIP, which is hereby incorporated by reference.[0080]

The[0081]

balloon member

116 is preferably a compliant balloon formed of a suitable elastic material such as a latex or the like. Theflexible coil122 is preferably formed of a wire of platinum or gold based alloys. The flexible core-wire120 and thetubular member114 are preferably formed of a superelastic nickel-titanium alloy.

The catheters of the present invention are preferably provided with a coating on the outer surface, or on both the inner and outer surfaces. Suitable coatings include hydrophilic, hydrophobic and antithrombogenic coatings. Examples include heparin and TEFLON. These coatings can be applied using methods well known in the art. The construction of catheter shafts and notches for fluid communication are discussed in Assignee's co-pending U.S. application Ser. No. ______, filed on the same day herewith (Atty. Docket No. PERCUS.055A), entitled SHAFT FOR MEDICAL CATHETERS, which is hereby incorporated by reference.[0082]

3. A preferred inflation apparatus[0083]

A preferred embodiment of a low volume or[0084]

inflation syringe

10 in asyringe assembly100 having features in accordance with the present invention is shown in FIG. 5. Also shown in FIG. 5 is an illustrative connection of theassembly100 to an occlusion balloon guidewire catheter12 (such as catheter221) utilizing aninflation adapter30. Thesyringe assembly100, comprising theinflation syringe10 and a larger capacity orreservoir syringe110, is attached viatubing216 to theinflation adapter30 within which a sealing member930 (see FIGS. 6A and 6B) and theballoon catheter12 are engaged during use.

The sealing[0085]

member

930, described in more detail below in connection with FIGS. 6A and 6B, is inserted into an open proximal end of thecatheter12. Thesyringe10 is used to inject inflation fluid through theadapter30 andinflation port17 into a lumen of thecatheter12, and into theballoon14. Theinflation adapter30, described in more detail below in connection with FIG. 7, is used to open and close the sealingmember930 to permit the inflation or deflation of theballoon14 mounted on the distal end of thecatheter12. However, it will be emphasized that other types of adapters, valves, and/or sealing members can be employed with the inflation syringe and/or syringe assembly of the present inflation, in order to achieve rapid and accurate inflation/deflation of medical balloons or other nonballoon medical devices. Therefore, although the present inflation is illustrated in connection with a lowvolume occlusion balloon14, other types of balloons and nonballoon devices can benefit from the advantages of the invention.

If the[0086]

balloon

14 is mounted on the distal end of thecatheter12, thesyringe10 and/orsyringe assembly100 is preferably connected at the proximal end of thecatheter12. Prior to use of thesyringe10 to inflate theballoon14 to the proper size for the vascular segment to be treated, the distal end of thecatheter12 and theballoon14 are first “primed” or evacuated. Thereservoir syringe110 of theassembly100 may be used for the evacuation. Access to the vascular site is through a port in the patient obtained, for example, using an introducer (not shown). A preferred system and method for accomplishing the occlusion balloon inflation is described below.

Generally, the[0087]

inflation syringe

10 of the present invention is provided with astop mechanism20 for limiting both the intake of fluid into the syringe and the delivery of fluid from the syringe. Thesyringe10 has anelongate cylinder44 andplunger arrangement50 which provide for greater displacement or travel by the plunger along the cylinder length than is necessary to expel a relatively small amount of inflation fluid. Thus, with thestop mechanism20, the clinician is provided with an enhanced sense of whether the fluid in thesyringe10 has been delivered to the balloon, which helps compensate for lack of precision by the clinician. Thestop mechanism20 may be mounted on thesyringe10 during production, or as separate components that can be retro-fit onto an existing supply of syringes.

Referring to FIGS. 5, 6A,[0088]6B, and7, thecatheter12 has the sealingmember930 inserted into its proximal end and has a side-access inflation port17, shown in greater detail in FIGS. 6A and 6B. Theinflation port17, proximal end of thecatheter12 and distal end of the sealingmember930 are positioned within the inflation adapter30 (see FIG. 7) to which asyringe assembly100 in accordance with the present invention has been operably coupled. Theinflation syringe10 is coupled via aninjection cap22 at its distal end to avalve112 that also connects thelarge capacity syringe110 and ashort tube segment216. Thetube segment216 is adapted to connect to a fitting ormale luer member24 of theinflation adapter30. Thus, the sealingmember930 is engaged by theadapter30 to allow use of thelow volume syringe10 of thesyringe assembly100 to inflate theballoon14 at the end of thecatheter12. Preferably, the sealingmember930 is as described in assignee's previously referenced co-pending U.S. application entitled LOW PROFILE CATHETER VALVE AND INFLATION ADAPTOR.

The catheter[0089]12 (depicted in FIGS. 6A and 6B) has aproximal end912, and a distal end (not shown in FIGS. 6A and 6B) to which is mounted theinflatable balloon14. Acentral lumen940 extends within atubular body918 between the proximal and distal ends. Anopening923 tolumen940 is present at theproximal end912 ofcatheter12. Theinflation port17 in fluid communication withlumen940 is provided ontubular body918.

The sealing[0090]

member

930 is inserted intolumen940 throughcentral lumen opening923. Sealingmember930 has afirst region935 which has an outer diameter substantially the same as the outer diameter of theproximal end912 of catheter tubular body.Region935 has ataper934, reducing in diameter to asecond region933 which has an outer diameter less than the inner diameter oflumen940.Region933 tapers overlength931 to form aplug mandrel wire932. As a consequence,region933 and plugmandrel wire932 are slidably insertable into theproximal opening923 ofcatheter12 and may freely move withinlumen940. In one preferred embodiment,region935 has an outer diameter of about 0.013 inches,region933 has an outer diameter of about 0.0086 inches, and plug mandrel wire has a diameter of about 0.005 inches, withregion933 and plugmandrel wire932 being inserted into a catheter having acentral lumen940 with an inner diameter of about 0.009 inches.

The length of sealing[0091]

member region

935 extending proximally ofcatheter12 may vary in length depending upon the intended use environment. For example, wherecatheter12 is to be used as a guide for other catheters in an “over-the-wire” embodiment, it is preferred that the total length ofcatheter12 and sealingmember region935 be about 300 centimeters. Alternately, wherecatheter12 is to be used in a single operator or rapid exchange embodiment, it is preferred that the total length ofcatheter12 andregion935 be about 180 centimeters. Accordingly, with a known catheter length and use environment, an appropriate length forregion935 may be chosen.

[0092]

Regions

935 and933 and plugmandrel wire932 may all be made out of metals such as stainless steel. Alternatively, combinations of materials may be used as well. For example, in some applications it may be desirable to manufacture

regions

935 and933 out of stainless steel, while manufacturingplug mandrel wire932 out nitinol. Furthermore, the various sealing member regions may be made from a single metal wire strand coined at various points to achieve the desired dimensional tolerances, or multiple segments may be joined together to form sealingmember930.

Where multiple segments are joined,[0093]

region

935,region933, and plugmandrel wire932 are attached to one another by any suitable means of bonding metal to metal, such as soldering, brazing, adhesives and the like. In one preferred embodiment, cyanoacrylate adhesives are used to adhere these various parts of sealingmember930 to one another.

As illustrated in FIGS. 6A and 6B, the outer diameter of sealing[0094]

member region

933 is less than the inner diameter oflumen940, such thatregion933 is slidably insertable intolumen940. In addition, the outer diameters of the taperedportions931 andwire932 are also small enough such that they too are slidably insertable inlumen940. However, the outer diameter ofregion935 is greater than theinner diameter940, and thus only a small portion of taperedportion934 of sealingmember930 betweenregion935 andregion933 is insertable intolumen940 throughopening923. Advantageously, this provides for a snug interference fit when sealingmember930 is fully inserted intocatheter12. This interference fit provides a frictional force which counteracts the tendency of the pressurized fluids and internal wire flexing in the catheter to push sealingmember930 out ofopening923.

As illustrated in FIGS. 6A and 6B, sealing[0095]

member

930 has movement-force increasing structure which increases the force required to move sealingmember930 withinlumen940. The movement-force increasing structure consists ofwaves938aand938bformed inwire932 near its distal end.Waves938aand938bcontact the inner surface oflumen940, thereby increasing the frictional force which must be overcome to movewire932 withinlumen940. In one preferred embodiment, wherewire932 is made of nitinol and has an outer diameter of about 0.005 inches, and is inserted into a nitinol catheter which has aninner lumen940 with a diameter of about 0.090 inches, waves are formed onwire932 for1-½ cycles with an amplitude of about 0.016 inches to increase the valve-opening movement force.

A[0096]

lumen sealer portion

936 is coaxially and fixedly mounted onwire932.Sealer portion936 forms a fluid tight seal with the outer diameter ofwire932 and the inner diameter oflumen940, such that fluid introduced intolumen940 through theinflation port17 is prevented from flowingpast sealer portion936 whensealer portion936 is inserted intolumen940 distally of theinflation port17.Sealer portion936 forms the fluid tight seal by firmly contacting the entire inner circumference of a section oflumen940 along a substantial portion of the length ofsealer portion936.

As shown in FIG. 6A,[0097]

sealer portion

936 is positioned proximally of theinflation port17, so that an unrestricted fluid passageway exists betweeninflation port17 and the inflatable balloon at the distal end ofcatheter12, which is like a valve “open” position. In this position,region933 is shown partially withdrawn from opening923. Referring to FIG. 6B,sealer portion936 is positioned distally ofinflation port17, so that fluid flow betweeninflation port17 and theinflatable balloon14 at the distal end ofcatheter12 are substantially blocked, which is like a valve “closed” position.

[0098]

Catheter

12 is changed from the valve open position to the valve closed position by the movement of sealingmember930 and its various components. Preferably, the exact length of movement needed to changecatheter12 from the valve closed to the valve open position is built into the movement function of the adaptor used to manipulate sealingmember930 thereby opening and closing the catheter valve. In this regard, it is preferred thatcatheter12 be used with an adaptor such asadaptor30, which provides for such controlled precise movement.

The “stroke-length”, or overall movement in one dimension, of sealing[0099]

member

930 required to open or close the valve may be varied depending upon the catheter requirements. When relying upon the inflation adaptor to control movement, however, it is important that the movement of the controlling elements of the adaptor be coordinated with those of sealingmember930. In one embodiment, where theinflation port17 is positioned 36 mm from opening923, a stroke length of 5.5 mm was found to be suitable.

Referring to FIGS. 5 and 7, the[0100]

inflation adapter

30 comprises a housing having two

halves

34,36 preferably formed of metal, medical grade polycarbonate, or the like. The

halves

34,36 are attached byhinges205 to be separated or joined in a clam shell manner. A lockingclip38 secures the halves while theadapter30 is in use. A groove within the housing has a width to accept the proximal end of thecatheter12 having the sealingmember930. The male luer member24 (FIG. 5), or other suitable connector, extrudes from a top of the housing to provide an inflation passageway.Seals280 are provided within the housing and around theinternal segment285 of the inflation pathway to conduct the pressurized fluid provided by thesyringe10 attached to themale luer member24.

An[0101]

actuator

40, shown in FIG. 5 at the top of the adapter housing, controls a cam which operates sliding panels291 (FIG. 7) contained in the housing. Preferably, thecatheter12 is positioned within the housing with the sealingmember930 in the closed position (FIG. 6B), such that theside inflation port17 is located in the sealedinflation area285 of the housing. An adjacent proximal portion of thecatheter12 extends outside the housing (and into the patient), and a proximal portion of the sealingmember930 extends out of the other side of the housing. The lockingclip38 is then secured and then thesyringe10 may be attached. Theactuator40 is moved from a first position to a second position, such that the slidingpanels291 within the housing cause the sealingmember930 to be in an open position to allow fluid flow through the inflation port17 (FIG. 6A). “Closing” the sealingmember930 is accomplished by moving the actuator40 from the second position back to the first position (FIG. 6B), such that the balloon inflation is maintained.

4. Multiple balloon embodiments[0102]

Referring now to FIGS. 8A and 8B, an alternative embodiment of the present invention is shown, in which a[0103]

first balloon

300 and asecond balloon305 bracket astenosis site310 within avessel315 during treatment, each balloon preferably being located within 4 cm of that site. The

balloons

300 and305 are joined to aradiation catheter320 through which aguidewire325 passes, which is preferably similar in construction to guidewire221. Theradiation catheter320 preferably has an O.D. of 0.070-0.120″ and is preferably 120-130 cm in length (e.g., 100 cm of 73D Pebax™ adjoining 20-30 cm of 35D Pebax™). Theguidewire325 is located within aguidewire lumen327 and is useful in positioning theradiation catheter320 at thestenosis site310. As shown in FIG. 8A, balloons300 and305 are in fluid communication with

respective inflation lumens

330 and335, respectively, so that they can be independently inflated and deflated after being positioned within thevessel315, thus permitting more accurate control of the balloons and reducing the risk of damaging healthy tissue. To permit the perfusion of blood, theradiation catheter320 preferably has two

perfusion holes

336 and337 located at respective ends of the radiation catheter, in which the

holes

336 and337 are connected by aperfusion lumen338, which is shown in FIG. 8B.

As in the embodiment of FIGS. 2A and 2B and the other embodiments herein, radiation may be delivered to the[0104]

stenosis site

310 in a number of ways, e.g., by bonding a radioactive source directly onto theradiation catheter320, or by injecting either a radioactive fluid or more preferably a fluid that containsradioactive carriers340 into alumen345. When injected into theradiation catheter320, the fluid passes through theinjection lumen345 and then into avent lumen350 before leaving theradiation catheter320. However, theinjection lumen345 preferably has a constriction355 (FIGS. 9A and 9B) therein so that theradioactive carriers340 stop at thestenosis site310. After thestenosis site310 has been treated, theradioactive carriers340 can be forced back out of the patient by injecting fluid into thevent lumen350 and back out theinjection lumen345.

As shown in FIG. 9A, the[0105]

radioactive carriers

340 may be cylindrical (between 0.010 and 0.040″ in diameter and between 0.020 and 0.200″ in length), or as illustrated in FIG. 9B, they may be spherical. If theradioactive carriers340 are of other oblong shapes, they are preferably constructed such they can be easily injected into and retrieved from theinjection lumen345. Theinjection lumen345 is preferably circular in cross section and 0.021-0.025″ in diameter before theconstriction355, at which point it may taper down to only 0.010-0.015″ in diameter. The first andlast particles360 in the train ofradioactive carriers340 are preferably radiopaque, and may comprise gold or platinum, to aid in locating the position of theradioactive carriers340 during visual fluoroscopy. Alternatively, the radiation may be delivered as shown in FIG. 9C, in whichradiopaque carriers360′ andradioactive carriers340′ are fastened to apull wire405 for insertion into aninjection lumen345′. This technique obviates the need for a vent lumen.

Another embodiment utilizing two balloons is illustrated in FIGS. 10A and 10B, in which balloons[0106]500 and510 are on the distal and proximal sides of thestenosis site505, respectively. Thedistal balloon500 is attached to aguidewire515 that passes through aguidewire lumen517 within acatheter520, the catheter being used for delivering radiation to thestenosis site505 and having itsown lumen522. Theproximal balloon510, on the other hand, is attached to aproximal catheter525 that surrounds theradiation catheter520. Thus, the distance separating the two

balloons

500 and510 is variable, giving the clinician added flexibility when centering theradiation catheter520 within the vessel at the stenosis site. Further, the

balloons

500 and510 are independently inflatable, thedistal balloon500 preferably being in fluid communication with the interior of theguidewire515, and theproximal balloon510 being in fluid communication with aninflation lumen530 within theproximal catheter525. Radiation is preferably delivered to thestenosis site505 using fluid that contains radioactive carriers. Aninjection lumen535 and avent lumen540 function similar to their counterparts in FIGS. 8A and 8B. Alternatively, a radiation source can be fastened directly to theradiation catheter520, as in the embodiments of FIGS. 2A and 2B, or to a wire, as in FIG. 9C.

5. Balloon at or near the stenosis site[0107]

FIGS. 11A and 11B show another embodiment of the invention, in which a[0108]

balloon

600 is attached to acatheter605 that delivers radiation to astenosis site610. Aguidewire615 within alumen617 in thecatheter605 facilitates proper placement of the catheter within thevessel620. Theballoon600 hasradiopaque strips630 thereon which substantially enclose aradiation source635 to shield the surroundings when the balloon is not inflated. Thestrips630 are preferably gold or platinum. Theballoon600 is preferably connected to aninflation lumen640 running through theradiation catheter605, so that as the balloon is inflated, thestrips630 move away from theradiation catheter605, opening upuncovered portions645 of the balloon between the strips to expose thestenosis site610 to theradioactive source635. Theradioactive source635 may be mounted directly to theradiation catheter605 as indicated in FIG. 11B or be delivered through lumens in the form of radioactive carriers, as discussed in connection with the embodiments of FIGS. 8A, 8B,9A,9B,9C,10A, and10B.

An embodiment similar to that of FIGS. 11A and 11B is shown in FIG. 12, in which an[0109]

inner balloon

760 that is preferably noncompliant is inflated to contact and expand a slittedouter balloon700. Theouter balloon700 hasslits770 betweenradiopaque strips730 of preferably gold or platinum, the slits being gaps in the outer balloon that, for example, may have been cut out of the outer balloon.

When the[0110]

inner balloon

760 is not inflated, thestrips730 of theouter balloon700 form a substantially radiopaque shield around aradiation source735. When theinner balloon760 is inflated, however, thestrips730 of the outer balloon move away from each other and theradiation source735 so that the strips are separated by theslits770. As theouter balloon700 expands, theslits770 increase in area so that radiation passes through the slits to treat a stenosis site. Theinner balloon760 may be inflated until theouter balloon700 contacts the vessel to be treated so that theradiation source735 is centered in the vessel. The embodiment of FIG. 12 also includes aradiation catheter705, aguidewire715, aguidewire lumen717, and aninflation lumen740 which function substantially like their counterparts in FIGS. 11A and 11B. In the embodiments of FIGS. 11A, 11B, and12, the

balloons

600 and700 may be periodically deflated and rotated, so that the stenosis site is more uniformly irradiated (i.e., so that portions of the stenosis site occluded by the

radiopaque strips

630 and730 are irradiated).

Radiation Centering Embodiments Using One or More Expandable Structures[0111]

The embodiments discussed below are similar to the previously discussed embodiments, except that expandable structures are employed rather than inflatable balloons. The expandable structures can comprise, for example, coils, ribs, a ribbon-like structure, a slotted tube, a filter-like mesh, or a braid. The expandable structures are preferably “spring-like” in nature, i.e. they are preferably resilient to facilitate their deployment or retraction. In addition, the expandable structures may optionally be radially asymmetrical with respect to the radiation catheter to which they are joined, such that treatment is delivered asymmetrically within the vascular segment. Any one of a number of ways may be used to secure the expandable structures to their respective sheaths, catheters, etc., such as welding, adhesives, or using rings to hold them in place. As in the previous embodiments, the radioactive source used in the expandable structure embodiments below may be secured directly onto the radiation catheter or delivered to the stenosis site through a lumen, e.g., a radioactive fluid, a fluid containing radioactive carriers, or a wire to which radioactive carriers are fastened. Details regarding intravascular occlusive devices are described in Assignee's co-pending U.S. application Ser. No. ______, filed on the same day herewith (Atty. Docket No. PERCUS.001CP2), entitled OCCLUSION OF A VESSEL, which is hereby incorporated by reference.[0112]

1. A single distal braid[0113]

In FIGS. 13A and 13B, for example, an embodiment is disclosed that is substantially analogous to that shown in FIGS. 2A and 2B. A[0114]

radiation catheter

800 delivers aradioactive source810 to astenosis site840, and aguidewire820 within the radiation catheter aids the clinician in properly positioning the radiation catheter within thevessel835 to be treated. Ashield catheter850 may be used to protect the surroundings and personnel from unwanted radioactive exposure.

An expandable structure (in this embodiment, a braid)[0115]830 is preferably attached on its proximal end to theguidewire820 and can be deployed, for example, with apull wire831 that passes through theradiation catheter800. Thebraid830 is shown in FIGS. 13A and 13B in the undeployed position and in FIG. 14A in the deployed position. When thebraid830 is deployed, it acts to center theradiation catheter800 within thevessel835 near thestenosis site840. The braids of these embodiments are preferably Elgiloy™, Nitinol, or stainless steel, preferably resilient, and are preferably either thin wires of 0.002-0.010″ diameter, or tiny ribbons of 0.002-0.005″ in thickness and 0.005-0.010″ in width. Thebraid830 of FIGS. 13A, 13B, and14A is shown as being the type that is deployed with apull wire831, but a self-expanding braid, such as that shown in FIGS. 15, 16A, and16B can also be used.

The[0116]

braid

830 is preferably porous enough to facilitate the perfusion of blood.

A preferred way of deploying the pull[0117]

wire type braid

830 is shown in FIGS. 14A and 14B. FIG. 14A illustrates thebraid830 being deployed by thepull wire831, which is attached to the distal end of the braid. Arotatable handle860 is attached to alocking element865 which in turn is fastened to thepull wire831. When thelocking element865 clears thecatheter800 within which it resides (which is preferably outside the patient), the locking element and rotatable handle860 may be oriented as illustrated in FIG. 14B to keep thepull wire831 taught, thereby preventing thebraid830 from returning to its undeployed position. The pull wire may be made of stainless or nitinol and may have a diameter of 0.006-0.008 inches.

An alternative to the deployment apparatus illustrated in FIGS. 14A and 14B is shown in FIG. 14C, in which a[0118]

handle member

190 is grasped by the clinician to retract thepull wire831, thereby deploying the expandable structure. Once extended, the expandable structure preferably has the tendency to return to its undeployed position, which in the process pulls thepull wire831 back into thecatheter800. This can be prevented by inserting aspacer member194 between thehandle member190 and thecatheter800. After the medical procedure is complete, and occlusion of the vessel is no longer required, thespacer member194 can be removed and thepull wire831 and the expandable mechanism returned to their respective undeployed positions. The device can then be removed from the patient.

2. A plurality of braids[0119]

Another embodiment illustrating the use of braids is illustrated in FIG. 15, which is substantially analogous to the two-balloon embodiment of FIGS. 10A and 10B. A[0120]

distal braid

1000 and aproximal braid1010 are preferably positioned on either side of astenosis site1005. When deployed as in FIG. 15, the

braids

1000 and1010 secure aradiation catheter1020 and itsradiation source1022, so that thestenosis site1005 can be uniformly irradiated. Aguidewire1024 aids the clinician in positioning theradiation catheter1020 within the patient. Thedistal braid1000 in this embodiment is attached to theradiation catheter1020, whereas theproximal braid1010 may be secured to aproximal catheter1025. Although pull wire braids can be used in this embodiment and in the embodiment of FIGS. 16A and 16B below, braids1000 and1010 are illustrated as being self-expanding. For example, the

braids

1000 and1010 may fit within asheath1050 before they are deployed, and be collapsed by thesheath1050 after treatment but before the device is removed from the patient. Alternatively,proximal sheath1025 may act as a sheath for thedistal braid1000, alternately deploying and collapsing it.

An alternative two-braid embodiment is shown in FIGS. 16A and 16B, in which two self-expanding braids are used, a[0121]

distal braid

1100 and aproximal braid1110 that surround astenosis site1105 to be treated. The

braids

1100 and1110 are shown in the deployed position and are attached toindentations1116 on a radiation catheter1120 (preferably made of Nylon, polyethylene, or Pebax™), so that the braids do not extend in the radial direction substantially beyond where theradiation catheter1120 would extend if it were not dented. Asheath1150 is used for alternately deploying and collapsing the

braids

1100 and1110. When they are deployed, the

braids

1100 and1110 help center theradiation catheter1120 within the vessel to be treated. Aguidewire1124 aids the clinician in positioning theradiation catheter1120 within the patient. As discussed in connection with the previous embodiments, radiation can be delivered, for example, through lumens within the radiation catheter1120 (e.g. radioactive fluid, radioactive carriers within a fluid, or radioactive carriers fastened to a wire) or by using a radioactive source attached directly to the radiation catheter.

The self-expanding[0122]

braids

1100 and1110 are shown in FIGS. 16A and 16B as extending less than 360 degrees around theradiation catheter1120, thereby reducing the risk of clot formation and permitting blood to flow around the braids.

For example, the[0123]

distal braid

1100 is illustrated in FIG. 16B as supporting theradiation catheter1120, but its radial extent around the radiation catheter is limited.

Likewise, the[0124]

proximal braid

1110 extends only partially around theradiation catheter1120.

3. Other expandable structures[0125]

The embodiments below also center a radiation delivering device in a vessel. It will be understood by those in the art that the following embodiments can be combined with the various radiation delivery technologies disclosed herein to form intravascular radiation therapy devices, especially self-centering devices. In particular, the flexible elongate members discussed below may be catheters such as radiation catheters.[0126]

Another embodiment using a braided structure is shown schematically in FIG. 17, in which a[0127]

flexible elongate member

3020 is disposed within asecond elongate member3024 such as a hypotube. Aself expanding mechanism3028 such as a braided structure is secured to the distal end of theelongate member3020, preferably within anindentation3032 ofmember3020, and centers one or both of the flexible

elongate members

3020 and3024 within the patient'svessel3040. Thebraided structure3028 may be partially encapsulated by a preferablyelastomeric membrane3036 that contacts the patient'svessel3040 and protects the vessel from abrasion. (Alternatively, a coating such as a polymeric coating may used in place of the membranes disclosed herein.) In this and the other embodiments, adhesive may be used to secure the self-expandingmechanism3028 and themembrane3036 to theelongate member3020. In the embodiment of FIG. 17, thebraided structure3028 andmembrane3036 are designed to be asymmetrical, with more material being concentrated at the proximal side of thestructure3028. The braids of the embodiments disclosed herein may be stainless steel304 or400, superelastic or heat activated Nitinol, or a polymer base, such as polyethylene or polypropylene. They may be constructed, for example, by using standard equipment such as a braider.

Although the embodiment of FIG. 17 shows the[0128]

flexible elongate member

3020 connected to aguidewire tip3044, other technologies for guiding the device through the patient'svessel3040 may be used in this and the following embodiments, such as a guidewire (either over the wire or single operator) or the exchange catheter method, as is well known in the art. Also, although not explicitly shown in the embodiment of FIG. 17 and the other embodiments herein, these embodiments may include various lumens (e.g., for delivering radiation), aspiration and irrigation fittings, and collars.

Although the[0129]

membrane

3036 may be impervious to the flow of blood (FIG. 18A) for those applications not requiring perfusion, aperforated membrane3036′ (FIG. 18B) havingnumerous holes3037 therein is preferably used in other applications to allow the passage of blood. Theholes3037 are preferably greater than 10 microns in diameter and may be up to 80 microns or more in diameter to permit the passage of blood cells (nominally 6-10 microns in diameter) through themembrane3036′ while blocking larger particulates such as emboli. Likewise, aperforated membrane3036′ is preferably used in the following embodiments. Antithrombogenic coatings can be used (e.g., heparin) to prevent thrombosis formation.

FIG. 19 shows a self-centering embodiment in which a[0130]

braided structure

3050 is not enclosed by a membrane. When thebraided structure3050 comprises, for example, a diamond mesh pattern in which adjacent wires are separated by about 10-80 microns, the braided structure permits the passage of red blood cells, while blocking the flow of matter that may be undesirable, e.g., emboli or other particulates that may be formed or dislodged during medical procedures. Thus, this embodiment is well suited for applications for perfusion.

Alternative self-expanding media for self-centering are shown in FIGS. 20 and 21. In FIGS. 20 and 21, a self-expanding filter-[0131]

like mesh

60 and a self-expanding slottedtube72, respectively, may be optionally surrounded by amembrane62 that is preferably perforated and elastomeric. The filter-like mesh60 (or slotted tube72) andmembrane62 are bonded or otherwise secured to a flexibleelongate member64, e.g., to an indentation therein. As with the other self-expanding media disclosed herein, the filter-like mesh60 (or slotted tube72) expands from its unexpanded state when the flexibleelongate member64 is pushed through a secondelongate member66, or alternatively, when the secondelongate member66 is retracted over the firstelongate member64. The filter-like mesh60 (or slotted tube72) then expands so that the membrane62 (if one is used) contacts the surroundingvessel68 to center one or both of the flexible

elongate members

64 and66, one of which is preferably a radiation catheter. Aguidewire tip69 aids in guiding the device through thevessel68. The filter-like mesh60 and slottedtube72 are of a suitable shape memory material such as Nitinol or (304 or400) stainless steel. The filter-like mesh60 is analogous to steel wool, whereas the slottedtube72 is like a stent in appearance. The slottedtube72 may be constructed, for example, by irradiating a thin-walled tube with a laser beam to form holes in the tube in the shape of polygons such as oblong quadrilaterals. An unexpanded, slottedtube75 is shown in FIG. 22.

FIG. 23 illustrates another self-centering embodiment, in which a[0132]

coil

80 serves as the self-expanding mechanism. The coil80 (which may be radioactive or have radioactive material fastened to it) may be integrally formed with a first elongate member82 (such as a radioactive wire) or be otherwise specially joined to it, e.g., by welding or brazing the coil to theelongate member82. Thecoil80 may be surrounded by a preferably perforatedmembrane84 that expands with the coil when it is pushed out of a second elongate member86 (which may be a radiation catheter), or alternatively, when the secondelongate member86 is retracted from thecoil80. Thus, the membrane84 (if one is used) contacts the surroundingvessel90. Themembrane84 may be attached directly to the firstelongate member82, or to amember88 such as a disk that is in turn secured to thecoil80 or the firstelongate member82. Aguidewire tip92 for guiding the device through thevessel90 may be attached to the firstelongate member82 or to themember88, if one is used.

An embodiment similar to that shown in FIG. 23 is illustrated in FIG. 24, in which the[0133]

membrane

84 is secured at the proximal end to aseparate sheath94. In this case, thesheath94 and the firstelongate member82 are retracted together over the secondelongate member86, or alternatively, they may be respectively pushed over and through the second elongate member.

Another embodiment for centering a radiation therapeutic device within a vessel that employs a self-expanding medium is shown in FIG. 25, in which a plurality of[0134]

ribbons

2100 contact avessel wall2104 or a (preferably perforated)membrane2102 to urge the membrane towards the wall of thevessel2104. Theribbons2100 of this embodiment are preferably secured to a firstelongate member2106 at both ends of the ribbons, by, for example, gluing them in place. The ribbons may be 0.001-0.004″×0.005-0.020″×0.25-1.0″ strips of Nitinol, stainless steel, or Elgiloy™, which expand when urged out of thesecond elongate member2108. Aguidewire tip2110 may be used for guiding the device through the vessel and is preferably secured to the distal end of the firstelongate member2106. The firstelongate member2106 or thesecond elongate member2108 may be a radiation catheter.

FIG. 26 illustrates an embodiment similar to the one in FIG. 25, in which[0135]

ribs

2120 such as wires form a series of semicircular arcs when expanded. Theribs2120 may be surrounded by a (preferably perforated)membrane2122 that expands with the ribs to contact thevessel2130 to center the device within thevessel2130. The number ofribs2120 is preferably at least three. Theribs2120 are preferably attached directly to a firstelongate member2124 that is surrounded by asecond elongate member2126, either of which may be a radiation catheter. Theribs2120 themselves are preferably made of a shape memory material such as Nitinol or stainless steel. Aguidewire tip2128 aids in guiding the device through thevessel2130.

As in the other self-expanding embodiments, the self-expanding mechanism[0136]2100 (2120) is in an unexpanded state when enclosed by the second elongate member2108 (2126), and expands when pushed or pulled beyond the second elongate member2108 (2126).

Centering mechanisms that are not self-expanding can also be used to center a radiation delivery device (such as a catheter) within a vessel, as is described below. In the embodiment of FIGS.[0137]27-29, a firstelongate member140, preferably a pull wire, is (when the device is completely assembled) attached to abrace member144 that is in turn attached to afirst ring member148. Adjoining thefirst ring member148 and asecond ring member152 are a plurality ofribbons156 that extend between the two ring members. Surrounding theribbons156 there may be a (preferably perforated) membrane160 (shown in partial cutaway in FIGS. 27, 28,30A,30B,30C, and30D) that contacts the patient'svessel162 when the ribbons are expanded. If it is used, themembrane160 is joined to at least one and preferably both of the

ring members

148 and152. Themembrane160 can be joined to only one of the

ring members

148 and152, for example, when themembrane160 extends far enough in the longitudinal direction to permit the membrane to contact thevessel162 when theribbons156 are deployed.

To assemble the device, the first and[0138]

second ring members

148 and152, theribbons156, and themembrane160 are placed as a unit around a secondelongate member166, which has a pair of

oppositely facing holes

170 and172. The secondelongate member166 may be a radiation catheter, for example. Thebrace member144 is inserted through the

holes

170 and172 and secured to both thepull wire140 and thefirst ring member148. Further, thesecond ring member152 is secured to the secondelongate member166. This assembled configuration, with theribbons156 in their longitudinal orientation, is illustrated in FIG. 28. As illustrated in FIG. 29, when thepull wire140 is retracted, the ribbons156 (shown in phantom) and themembrane160 that surrounds them are urged towards thevessel162, where the membrane contacts the vessel to center the secondelongate member166. Theribbons160 are preferably resilient enough that they return to their longitudinal orientation when thepull wire140 is released. The elasticity and resilience of thepull wire140 also helps theribbons156 return to their undeployed configuration. Aguidewire tip171 may be used to assist in guiding the device to the desired location in thevessel162. Preferred ways of deploying guidewires are discussed above in connection with FIGS. 14A, 14B, and14C.

Although the principle of using a nonself-expanding mechanism has been illustrated in FIGS.[0139]27-29 with respect to deformable ribbons, other nonself-expanding mechanisms can be employed in conjunction with thebrace member144 and the first and

second ring members

148 and152. For example, instead of usingribbons156, a nonself-expandingbraided structure200 can be used, in which thebraided structure200 adjoins first and

second ring members

148 and152 and is optionally covered with a preferably perforated membrane160 (to allow perfusion) to form theunit204 shown in FIG. 30A. Theunit204 can be used in conjunction with anelongate member166, abrace member144, aguidewire tip171, a firstelongate member140 such as a pull wire, arotatable handle180, and a lockingmember184 to form a device analogous to the ribbon-based device of FIG. 27. Alternatively, other mechanisms can be used for securing thepull wire140, such as ahandle member190 and aspacer member194.

Other nonself-expanding mechanisms such as a filter-like or[0140]

fibrous mesh

208, a slottedtube212, and coils217 can be used to form

units

220,230, and240 analogous to thebraided structure unit204, as shown in FIGS.30B-30D.

Units

220,230, and240 can likewise be used to construct devices analogous to the ribbon-based device illustrated in FIGS.27-29. Further, ifunit204 is used without a membrane, it may assist in blood perfusion if thebraided structure200 is suitably constructed. Alternatively, perforated membranes likemembranes3036′ of FIG. 18B may assist in blood perfusion. Although theribbons156, thebraided structure200, the filter-like mesh208, the slottedtube212, and thecoils217 must be actively deployed (e.g. with a pull wire140), they are nevertheless similar to their self-expanding counterparts.

The centering technology disclosed herein can be utilized in other procedures, such as in atherectomy, as shown in FIG. 31, which shows an embodiment that is analogous in many respects to the embodiment of FIG. 10A. A[0141]

proximal catheter

525′ surrounds anatherectomy catheter520′ to which aboring mechanism502′ is attached. When theatherectomy catheter520′ rotates, theboring mechanism502′ engages astenosis site505′ to widen the constriction. The device may be centered with distal andproximal balloons500′ and510′, or alternatively, with expandable structures such as those disclosed herein. Aguidewire515′ may be used when positioning the device within the vessel.

Another application of the centering technology disclosed herein is illustrated in FIG. 32, in which a[0142]

laser beam

503″ is preferably directed through afiber optic504″ onto a vessel or a vessel'sstenosis site505″. Aproximal balloon510″ (alternatively, an expandable structure such as that disclosed herein) may be used to position, aim, or center the device. Theballoon510″ is preferably secured to aproximal catheter525″.

It should be understood that the scope of the present invention is not be limited by the illustrations or the foregoing description thereof, but rather by the appended claims, and certain variations and modifications of this invention will suggest themselves to one of ordinary skill in the art.[0143]

Claims

What is claimed is:

1. A radiation device for treating a segment of a vessel in a patient, comprising:

a catheter for delivering radiation;

a radioactive source in proximity with said radiation catheter;

a noncompliant balloon around said radioactive source;

a lumen within said radiation catheter that is in fluid communication with said noncompliant balloon, permitting inflation and deflation of said noncompliant balloon; and

a compliant balloon that surrounds said noncompliant balloon, wherein said compliant balloon expands as said noncompliant balloon expands to radioactively treat the vascular segment.

2. The device ofclaim 1, in which said compliant balloon has slits therein, the area of said slits increasing as said compliant balloon expands to more directly expose the vascular segment to radioactive treatment.

3. The device ofclaim 2, in which said compliant balloon comprises a shielding layer to prevent unwanted radioactive exposure of the surroundings when said compliant balloon is not inflated.

4. The device ofclaim 3, in which said shielding layer comprises a material selected from the group consisting of platinum and gold.

5. The device ofclaim 1, further comprising a guidewire within said radiation catheter for directing said radiation catheter through the vessel.

6. A radiation device for treating a segment of a vessel in a patient, comprising:

a catheter for delivering radiation;

a radioactive source in proximity with said radiation catheter;

a balloon around said radioactive source;

a lumen within said radiation catheter that is in fluid communication with said balloon, permitting inflation and deflation of said balloon; and wherein

said balloon has strips of material thereon that substantially shield the surroundings from unwanted radioactive exposure when said balloon is not inflated, the area between said strips increasing as said balloon expands to more directly expose the vascular segment to radioactive treatment.

7. The device ofclaim 6, further comprising a guidewire within said radiation catheter for directing said radiation catheter through the vessel.

8. A self-positioning radiation device for treating a segment of a vessel in a patient, comprising:

a catheter for delivering radiation;

at least one expandable structure for securing said radiation catheter within the vessel; and

a radioactive source for treating the vascular segment, said radioactive source in proximity with said radiation catheter.

9. The device ofclaim 8, in which said expandable structure is self-expanding.

10. The device ofclaim 9, in which said self-expanding expandable structure is attached to an indentation on said radiation catheter.

11. The device ofclaim 8, in which said expandable structure is braided and attached to a pull wire that deploys said at least one expandable structure.

12. The device ofclaim 8, in which said expandable structure is attached to said guidewire.

13. The device ofclaim 8, in which the radial extent of said expandable structure when said expandable structure is deployed around said radiation catheter is less than 360 degrees, permitting perfusion around said expandable structure and reducing the risk of clot formation within said expandable structure.

14. The device ofclaim 8, in which one expandable structure is located distal to the vascular segment.

15. The device ofclaim 8, further comprising a guidewire within said radiation catheter for directing said radiation catheter through the vessel.

16. The device ofclaim 8, comprising two expandable structures.

17. The device ofclaim 16, further comprising a sheath for expanding and compressing said expandable structures.

18. The device ofclaim 16, further comprising a proximal catheter that acts as a sheath for expanding and compressing one of said expandable structures.

19. The device ofclaim 18, in which one of said expandable structures is attached to said proximal catheter and the other of said expandable structures is attached to said radiation catheter.

20. The device ofclaim 16, in which both of said expandable structures are attached to said radiation catheter.

21. The device ofclaim 20, further comprising a sheath for expanding and compressing both of said expandable structures.

22. The device ofclaim 8, further comprising:

an injection lumen within said radiation catheter for accepting fluid that contains radioactive carriers, said injection lumen having a constriction therein beyond which said carriers cannot advance, said constriction positioned so that said carriers effectively treat the vascular segment; and

a vent lumen, wherein said injection lumen and said vent lumen are in fluid communication with each other, permitting said carriers to be injected into said injection lumen by passing said fluid from said injection lumen into said vent lumen, said carriers being retrieved by passing said fluid from said vent lumen into said injection lumen.

23. A method of treating a segment in a vessel, comprising:

inserting a catheter into the vessel;

inserting a plurality of balloons into the vessel, wherein at least two of the balloons are independently inflatable;

inflating at least two of the independently inflatable balloons to position the catheter away from the walls of the vessel; and

exposing the vascular segment to radiation treatment.

24. The method ofclaim 23, further comprising:

deflating the inflated balloons after the treatment; and

removing the balloons and the catheter from the vessel.

25. The method ofclaim 23, in which said exposing of the vascular segment to radiation comprises injecting radioactive carriers through a lumen in the catheter.

26. A method of treating a segment in a vessel, comprising:

inserting a first balloon into the vessel;

placing the balloon near the vascular segment to be treated; and

expanding the balloon to expose the vascular segment to radiation that is concentrated along an axis centered within the balloon.

27. The method ofclaim 26, in which the balloon is attached to a catheter.

28. The method ofclaim 26, in which the balloon has radiopaque strips thereon for shielding the surroundings from radiation when the balloon is not inflated.

29. The method ofclaim 28, wherein

the first balloon has slits between the strips; and

said expanding the first balloon comprises inflating a second balloon to expand the first balloon, the second balloon being in contact with and located within the first balloon.

30. A method of treating a segment in a vessel, comprising:

inserting a catheter into the vessel;

inserting at least one expandable structure into the vessel;

expanding the expandable structure to position the catheter away from the walls of the vessel; and

treating the vascular segment by exposing it to radiation.

31. The method ofclaim 30, further comprising:

compressing the expandable structure after treatment; and

removing the expandable structure and the catheter from the vessel.

32. The method ofclaim 30, in which said exposing of the vascular segment to radiation comprises injecting radioactive carriers through a lumen in the catheter.

33. The method ofclaim 30, in which said expanding the expandable structure comprises pulling on a wire.

34. The method ofclaim 30, in which at least two expandable structures are used to position the catheter.

35. The method ofclaim 34, in which a plurality of sheaths are used to deploy and compress the expandable structures.

36. The method ofclaim 30, in which said treating the vascular segment comprises introducing radioactive carriers attached to a wire.

37. A radiation device for treating a segment of a vessel in a patient, comprising:

a catheter;

a guidewire within said catheter for directing said catheter through the vessel; and

a radioactive source fastened directly onto said catheter.

38. The device ofclaim 37, further comprising a retractable shield that surrounds said radioactive source when the vascular segment is not being treated.

39. The device ofclaim 37, in which said radioactive source is bonded onto said catheter.