Irradiation catheter

The present invention belongs to the field of devices used to radiate nuclear radiation to a portion of a blood vessel to prevent restenosis of the irradiated area after performing an angioplasty.

A common problem that arises after performing coronary angioplasty across the percutaneous lumen is restenosis of the treated area. In fact, restenosis occurs in 30% to 50% of cases. Restenosis occurs, at least in part, as a result of migration, proliferation, and neointima formation of vascular smooth muscle cells at the site of angioplasty. Irradiation of ionizing radiation into the coronary arteries creates a nest-like medial fibrous fissure, which, when delivered to the site of angioplasty, prevents the progression of restenosis. This irradiation procedure does not damage parts of the adjacent coronary arteries and the surrounding myocardium. Irradiation of ionizing radiation at the stenotic site can be performed by introducing an irradiation ribbon through an infusion catheter. In known systems, an infusion catheter is inserted into the stenosis site via a guide wire, which may be inserted before the angioplasty procedure and left there after the procedure. After insertion of the infusion catheter, the guide wire is removed and a irradiation ribbon is inserted in its place. Irradiation ribbons typically incorporate multiple iridium-192 seeds (small containers) or pellets near their far end. Other ionizing radiation sources can be used as well.

The plurality of radioactivity sources are basically arranged in a line and become approximate radiation sources, but the intensity of radioactivity varies to some extent in the axial direction depending on the seed spacing and length. The irradiation ribbon is inserted at the point where the radioactive substance is placed in the narrowed part. Iridium-192 emits gamma rays with energies in the range of 296 to 612 x 1000 electron volts (keV). Currently known systems have some drawbacks. First, the guide wire must be pulled back before inserting the irradiation ribbon. Pulling back the guide wire is not welcomed by the surgeon as it adds at least one step to the procedure and takes extra time. Performing extra steps increases the chances of complications. In angioplasty, time is a crucial factor because most of the procedures impede the flow of blood in the blood vessels, at least partially, which has a detrimental effect on the muscles that supply the blood. This problem is complicated during the irradiation procedure because the source of radiation often has to be left in place for several minutes in order to irradiate the desired dose to the vascular tissue. The time issue is further complicated by the need to reinsert the guide wire after irradiation in some cases.

The second drawback of known systems is that the irradiation ribbon is exposed to blood flow in the infusion catheter, and some radioactive seeds are lost from the far end of the infusion catheter or the irradiation ribbon itself. Can be broken.

The third drawback is that the location of the radioactive material is largely radially uncontrollable within the blood vessel. Rotation of the infusion catheter may help align the source of radiation within the stenosis, but this method is not always effective. Since it is important to evenly irradiate the affected tissue with a known radiation dose, it may be necessary to align the radioactive material inside the tissue damaged by angioplasty. The intensity of gamma rays emitted from a source varies in inverse proportion to the square of the radial distance from the source. Therefore, if the radiation source is not located in the center of the inside of the blood vessel, the dose radiated to one side of the blood vessel may be significantly different from the dose radiated to the other side. In addition, if the source is not concentric or at least not parallel to the vessel and is located at an angle to the centerline of the vessel, the dose may vary significantly axially over the entire length of the stenosis. There is. In some cases, if one side of the stenosis is to be irradiated more than the other side, it may be desirable to place the radiation source parallel to the centerline of the blood vessel but offset from it. Such treatment may be desired if restenosis is expected due to greater tissue growth on one side than that on the other side.

<p> One object of the present invention is to provide a catheter / assembly for irradiating a stenotic portion of a blood vessel that can be inserted into a stenotic site via a guide wire. Another object of the present invention is to provide a catheter / assembly capable of arranging an irradiation source at a desired position inside a blood vessel in both the axial direction and the radial direction. Yet another object of the present invention is to provide a catheter / assembly that can be economically manufactured and is easy to use.</p>

<p> An outline of a preferred embodiment of the present invention will be described by way of example. The present invention provides a catheter to be used together with an irradiation ribbon, which is configured to be inserted into a predetermined position inside a blood vessel via a guide wire. The catheter body has a lumen in which the irradiation ribbon is inserted. The lumen can be sealed at the far end of the catheter body to completely retain the irradiation ribbon and the radioactive material incorporated therein.</p><p> A guide wire groove is formed on the catheter body apart from the lumen, and at least a part of the guide wire groove is formed near the far end of the catheter body. The guide wire groove is formed so that only a short portion is formed at the far end, and the catheter is used as a rapid exchange catheter as described in the patent application on which the priority of the present application is based, which is cited above. It can also be used. Alternatively, guide wire grooves may be formed in two separate portions, one portion near the far end and the other near the near end of the catheter body. The near end portion has a structure surrounding the guide wire, which can be sealed by the O-ring of the guide catheter, and the guide wire can move freely. Furthermore, the guide wire groove can also be formed with a film that can be split in the longitudinal direction. In such a configuration, the far end is basically used for quick replacement and the near end is used for sealing. The latter two embodiments are described in detail in the applications listed above. In both of these subsequent two embodiments, the catheter can be used through the guide catheter to provide a closed surface for the fluid at the near end, to which the O-ring of the guide catheter is sealed. It is possible to inject the dye so that the radiation source is visible and at the same time move the guide wire freely to help position the catheter, which will be described later.</p><p> Since it may be desirable to position the radiation source radially inside the blood vessel, the present invention provides at least two methods and several types of devices for performing radial positioning. The first method does not require any special equipment and can be used by introducing one or more bends near the near end of the guide wire. When the catheter and irradiation ribbon are in the axially predetermined position within the constriction area, if the far end of the catheter is not in the desired radial position, rotate the guide wire to shift the curved portion in the direction in which you want to shift the catheter. Can be turned. The guide wire can then be pulled back slightly and one or more bends can be pulled back into the far end of the guide wire groove. Bends in the guide wire allow the guide wire to exert a force on the wall of the guide wire groove, thereby flexing the catheter body as much as desired in the direction of the force and placing the far end of the catheter in the desired position in the radial direction. To.</p><p> In another method, the catheter can be provided with means for radially positioning the radiation source inside the blood vessel. Often, this positioning means is used to align the radiation source in the radial direction. The positioning means can be configured in various ways, two examples of which include the use of inflatable balloons and inflatable wire loops. The inflatable balloon can be formed as a coiled or a plurality of substantially annular balloons. One or more balloons can be connected to an inflatable lumen formed on the catheter body for inflating. Alternatively, a plurality of flexible wire loops may be attached near the far end of the catheter body, one end of each loop may be fixed to the catheter body, and the other end may be free. The wire loops may be configured to expand automatically when released, or the free ends of each loop may be attached to an extension means that allows the user to move vertically, thereby allowing the free ends of the wire loops to expand. It can also be configured to move toward the mounting end. This movement extends the loop outward. The loops are spaced around the catheter body and the dilation aligns the catheter inside the vessel. The extension means can be a relatively stiff wire configured to push the free end of a nearby wire loop, or a wire configured to push the free end of a wire loop located far away. The automatically expanding wire loop expands when the holding exterior is pulled back, without the help of expansion means.</p><p> The novel features of the invention and the structure and operation of the invention will be well understood from the detailed description given below with reference to the accompanying drawings. In the drawings, the same reference numerals indicate the same parts.</p>

Description of Preferred Embodiment As shown in FIGS. 1 and 2, the first embodiment of the irradiation catheter / assembly 10 of the present invention is a catheter body 12 having an inner lumen 14 with a substantially closed far end 13. An irradiation ribbon 16 that can be inserted into the lumen 14, a groove 18 for a distal guide wire for guiding the catheter body 12 along the guide wire 20, and a proximal guide wire for sealing the guide catheter O-ring. It consists of a groove 19, a coiled centering balloon 22, and an inflatable lumen 24 to which the centering balloon 22 is attached. As will be described later, some of these elements may take other forms in other embodiments without departing from the spirit of the invention.

The catheter body 12 is an elongated, hollow, flexible, tubular, preferably made of plastic material. The near end 15 of the catheter body 12 is divergent so that the irradiation ribbon 16 can be easily inserted into the medial lumen 14. If the irradiation ribbon 16 is sized to substantially fill the inner lumen 14, the irradiation source can be arranged concentrically with the catheter body 12. The far end 13 of the catheter body 12 is closed to hold the irradiation ribbon 16 and its radioactive material. A guide wire groove 18 is formed on the catheter body 12 away from the inner lumen 14. The guide wire groove 18 can be formed as a duct attached to the wall of the catheter body 12 as shown, can be formed inside the inner lumen 14, or can be formed inside the wall of a thick catheter. It can also be formed as a passing lumen. The illustrated guide wire groove portion 18 is formed only near the far end of the catheter body 12, and the near end of the guide wire 20 placed at a predetermined position is inserted through the guide wire groove portion 18, and the catheter body 12 is further inserted. The catheter body 12 can be easily used as a rapid exchange catheter by inserting it into the patient via a guide wire 20 placed at a predetermined position.

As an option, a second guide wire groove 19 similar to the distal guide wire groove 18 is formed near the near end of the catheter body 12 and guide catheter O when dye injection is used. -A closed surface for the ring (not shown) can also be provided. Sealing with the O-ring can be done without restricting the movement of the guide wire. The proximal guide wire groove portion 19 is arranged such that its far end is closer to the far end 13 of the catheter body 12 than the length of the guide catheter used. This ensures that the guide catheter O-ring surrounds the proximal guide wire groove 19 when the far end 13 of the catheter body 12 reaches the far end of the guide catheter.

The same effect can be obtained by forming the guide wire groove 18 so as to extend over the entire length of the catheter body and forming a film capable of tearing in the vertical direction in the wall of the groove. This basically disposes of a distal guide wire groove portion and a proximal guide wire groove portion, which are formed as different portions of a single groove. Due to the incorporation of a tearable membrane, these portions of the guide wire groove can be used as separate grooves. The use and manufacture of this type of catheter is disclosed in detail in the drawings and specification of the patent application mentioned above that underlies this application and is incorporated herein by reference. The coiled centering balloon 22 is attached to the catheter body 12 at a plurality of attachment points 32 that are spaced apart along both sides of the catheter body 12. These attachment points 32 are used for surface attachment by solvent bonding, ultrasonic welding, etc., and no communication occurs between the balloon coil 22 and the inner lumen 14. The coil 22 of the alignment balloon is shown in an inflated state.

When the balloon coil 22 is deflated for insertion or withdrawal, the coil becomes approximately flat on the catheter body 12. When inflated, the balloon coil 22 is pulled inward at a point 34 adjacent to the attachment point 32 to form a constricted shape, as shown. This produces two ends or round protrusions 36 for each loop of the balloon coil 22. Any number of round protrusions can be used depending on the intended use of the assembly 10. The protrusions 36 and 38 extend equal distances from the catheter body 12 when inflated, placing the catheter body 12 and thus the irradiation ribbon 16 radially centered inside the blood vessel. If the radioactive material is to be positioned closer to one side of the vessel, the balloon coil 22 can be provided with only one protrusion per loop, or one protrusion 36 can be made longer than the other protrusion 38. Similarly, each loop of the balloon coil 22 also has the same rounded protrusions 36 and 38 as shown to ensure that the catheter body 12 is held parallel to the wall of the blood vessel. If the catheter body is placed at an angle along the blood vessel and a particular constriction is expected to be exposed to radiation, the adjacent loops of the balloon coil 22 are dimensioned without departing from the spirit of the invention. It can also be formed with different rounded protrusions.

In the figure, the balloon coil 22 is attached at its far end 26 and near end 28 so as to circulate in the expansion lumen 40 inside the expansion groove 24. In the case of wishing, a single flow connection may be made at any point along the coil 22 of the balloon. In the figure, the inflatable groove 24 is formed as a duct on the wall of the catheter body 12, but can also be formed inside the medial lumen 14, or the inflatable lumen 40 is formed through the wall of the catheter. You can also do it. The inflatable lumen 40 has an inlet 30 into which the inflatable fluid is introduced. 3 and 4 show other embodiments of the catheter assembly 10'of the present invention. The catheter body 12', the guide wire groove 18, and the expansion groove 24' of this embodiment are substantially the same as those of the first embodiment. The main difference between the two embodiments is that the radial positioning balloon or centering balloon is formed as a plurality of substantially annular balloon rings 42. Each balloon ring 42 has two ends or round protrusions 44 and 46, which have essentially the same function as the round protrusions 36 and 38 on the balloon coil 22 of the first embodiment. Fulfill. Each balloon ring 42 is mounted so as to circulate in the expansion lumen 40'at a plurality of attachment points 32'arranged along the expansion groove 24'. The flow between the inside of the balloon ring 42 and the inflatable lumen 40'is through a plurality of inflatable inlets 48 located at attachment points 32'. In addition to the two types shown above, other forms of positioning balloons could be devised without departing from the scope of the present invention.

5, 6, and 7 show still other embodiments of the catheter assembly 10 of the present invention. A plurality of flexible wire loops 50 are disposed adjacent to the portion of the catheter body 12'' where the irradiation source is located. In FIG. 5, the wire loop 50 is in a contracted state, the far end 54 is fixed to the catheter body 12'', and the near end 56 is mobile with respect to the catheter body 12''. Each free end 56 is attached to a relatively rigid expansion wire 52, and a plurality of expansion wires 52 are configured to pass through an expansion wire guide groove 58 formed on the catheter body 12''. The catheter assembly 10 also has a guide wire groove 18 as in the two embodiments above. However, in FIG. 5, the guide wire is not shown for clarity.

FIG. 6 shows a state in which the far end of the extension wire 52 is pushed to expand the wire loop 50, thereby pushing the free end 56 of the wire loop 50 toward the mounting end 54. By selectively expanding the wire loop 50 in this way, the catheter body 12'' is radially aligned or centered inside the vessel. Alternatively, the free end of the wire loop 50 is placed near the far end of the catheter body and the mounting end is located proximally, pulling the extension wire to pull the free end towards the mounting end to pull the wire loop. It can also be expanded. In addition, self-expanding wire loops can be used to allow expansion to occur when the restraint exterior is pulled back. All of these embodiments are also practiced in the spirit of the present invention.

Irradiation can be performed before or after performing the angioplasty procedure. In either case, the guide wire 20 is inserted in place at the constriction site. If the angioplasty balloon catheter is in place, it can be pulled back from the guide catheter to leave the guide wire 20 in place. The near end of the guide wire 20 is inserted into the far end of the guide wire groove 18 on the catheter assembly 10, 10', 10'' of the present invention. Next, the catheter body 12 is inserted into the stenosis site via the guide wire 20. The irradiation ribbon 16 can be placed inside the catheter body 12 prior to this insertion, or can be inserted into the catheter body 12 after the catheter body 12 is placed in a predetermined position. If the embodiment used incorporates a proximal guide wire groove 19 or a tearable membraned full-length groove, a guide catheter O-ring is sealed around the near end of the catheter body 12. The dye can be easily injected while tightening to and allowing the guide wire to move freely. Such a configuration is useful for positioning while looking at the radiation source. Further, by using the proximal guide wire groove 19 or the groove over the entire length, the guide wire can be freely moved with respect to the catheter body as described above. When the radioactive seed is placed in place within the expanded area of the blood vessel, an inflatable fluid is introduced into the inflatable lumen 40 and pressurized, such as balloon coil 22 or balloon ring 42. The positioning balloon is inflated to radially position or align the catheter body 12 inside the vessel.

Alternatively, the positioning balloon can be inflated first and then the irradiation ribbon can be inserted. When using the wire loop positioning means, of course, the extension wire 52 can be used to extend the wire loop 50. Instead of using a positioning balloon or wire loop, it may be desirable to use a curved guide wire that radially positions the far end of the catheter body. If the surgeon observes that the far end of the catheter body 12 on which the irradiation seed is placed is not radially aligned as desired, first rotate the guide wire 20 to look into the bend. Aim at the far end of the guide wire 20. The bend can be a relatively mild bend, as shown in FIG. 1 or 3, or can be more prominent, depending on the physical shape of the vessel and the stenosis to be treated. In addition, it may be appropriate to use a series of bends. These bends can be introduced into the guide wire 20 before the guide wire 20 is first inserted, or if the catheter used has a groove for the guide wire over the entire length, the guide wire 20 can be inserted. It can also be pulled back, curved appropriately and reinserted. After rotating the guide wire 20 to direct the bend in the desired deflection direction of the catheter body 12, the catheter body 12 is held in a predetermined position in the vertical direction, and the far end of the guide wire 20 is placed in the groove for the guide wire. Carefully pull back into the far end of 18. When the bend on the far end of the guide wire 20 enters or begins to enter the far end of the guide wire groove 18, the guide wire 20 exerts a lateral force on the wall of the guide wire groove 18. This lateral force is then transmitted to the far end of the catheter body 12 and deflects it in the direction looking into the far end. Regardless of the method used to position the source in the radial direction, the source is then left in place until the desired dose is applied. After obtaining the desired dose of radiation, leaving the radiation source in place for a desired period of time, the guide wire 20 is used to pull back the catheter assembly 10 and insert the angioplasty catheter or perform any other necessary procedure. Can be left in place.

The specific irradiation catheter illustrated and described in detail above can sufficiently achieve the above-mentioned object and sufficiently exhibit the effect, but is merely for explaining a preferred embodiment of the present invention. It will be appreciated that it is not intended to limit the details of the structure and configuration of the irradiation catheter according to the present invention. The present invention is limited only by the claims set forth below.

<figref num="1">FIG. 1 is a perspective view of the first embodiment of the irradiation catheter of the present invention.</figref><figref num="2">FIG. 2 is a cross-sectional view taken along line 2-2 of the catheter shown in FIG.</figref><figref num="3">FIG. 3 is a perspective view of a second embodiment of the irradiation catheter of the present invention.</figref><figref num="4">FIG. 4 is a cross-sectional view taken along line 4-4 of the catheter shown in FIG.</figref><figref num="5">FIG. 5 is a perspective view of a third embodiment of the irradiation catheter of the present invention.</figref><figref num="6">FIG. 6 is a perspective view showing a state in which the wire loop of the catheter shown in FIG. 5 is in the extended position.</figref><figref num="7">FIG. 7 is a cross-sectional view of the catheter shown in FIG.</figref>