Fiber optic guide wire

Abstract: A guide wire (20) for a catheter has a solid tubular portion with a flexible body fixed to its distal end (22). The distal end (22) of the body may be composed of a material more radiopaque than its proximal portion. Optical fibers (24) are disposed within the assembly and terminate in a radiopaque tip at the distal end (22) of the body. The guide wire (20) may have a longitudinal marker wire (32) for providing stiffness and radioscopic tracking characteristics. The guide wire (20) has a proximal end attached to the tube and a distal end (22) that also terminates in the tip. The invention may be maneuvered and positioned in a vascular area like a conventional guide wire. Then, laser energy from a laser light source at a proximal end of the guide wire is conveyed to the vascular area by the optical fibers (24) to ablate an obstruction. A larger catheter may then be slid over the guide wire to continue the ablation operation. Employing polyester tubing for the distal body, the guide wire may be used in peripheral angioplasty applications. Alternatively, the distal body may be implemented with a metal coil and may be used in coronary angioplasty.

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiber optic guide wire apparatus used with catheters for surgical operations, and more specifically, to catheters such as fiber optic catheters used for illuminating and ablating intravascular regions and to guide wires for positioning such catheters. 2. Description of the Related Art Angioplasty, a therapeutic medical procedure in which a catheter or the like is inserted into a blood vessel to increase blood flow, has developed in many cases as a safer, less expensive alternative to by-pass surgery. The first catheters for angioplasty were balloon catheters built up around a steerable guide wire core. The catheter is inserted into the vessel until the position of the balloon corresponds to the position of an obstruction in the blood vessel, and then the balloon is pressurized, opening the artery and increasing blood flow. Typically, a steerable guide wire passes through the balloon catheter and is able to move independently of the catheter. The guide wire, of relatively small diameter, is inserted into the patient's blood vessel and moved into proper position past the obstruction. Then the balloon catheter, surrounding the guide wire, is advanced along the guide wire until the catheter is in proper position, with the balloon at the obstruction. This guide wire and catheter combination allows the guide wire to be inserted into place before the catheter thus making it easier to position the catheter. Catheters containing optical fibers have also been constructed for insertion into veins and arteries. Energy is conducted along the fibers to irradiate internal parts of the body for diagnostic and surgical purposes. There are also many other medical applications in which it is desirable to deliver energy, such as laser energy, through an optical fiber or similar waveguide device disposed in a body cavity for treatment or diagnosis. These include the ablation of tissue such as plaque and tumors (e.g., angioplasty), the destruction of calculi and the heating of bleeding vessels for coagulation. The lasers used may produce either pulsed or continuous-wave light of wavelengths ranging from the ultra-violet to the infra-red. Like balloon catheters, laser catheters are generally used with a guide wire to steer and position the catheter in the patient's body. EP 0 355 996 A2 shows a guidance and delivery system for high-energy pulsed laser light and endoscope. It comprises a wire coil having a distal end and an optical fiber having a distal end and extending axially through the center of the wire coil. The distal end of the optical fiber is bonded to the distal end of the wire coil. This optical fiber/guide wire combination moves relative to and projects distally from the catheter structure with which it is used. Therefore, the exit surface for light exciting from the fiber is spaced apart from the distal face of the catheter assembly which leads to a reduction of intensity of light emanating from the optical fiber. EP 0 399 660 A1 shows a hot tip device with optical diagnostic capability. This device includes a glass heating element that absorbs a first range of wavelengths for heating the same to melt plaque. Although this document teaches that some optical energy can pass through the heating element, it is taught as for the purpose of stimulating florescence and/or for viewing. Therefore, this device is not able to be used for ablating plaque from within an artery with e.g. excimer laser energy. Further, this device requires that the light pass through an element which has some optical effect to the light. Laser and balloon techniques may be combined in an angioplasty process. An example of such a technique is given in U.S. Patent 4,834,093 to Littleford et al. In this patent, a laser catheter is introduced into an intravascular area with the aid of a guide wire. The catheter/guide wire combination is positioned near a vascular occlusion, and the catheter is used to deliver laser energy to the occlusion to ablate a channel through the occlusion. While leaving the guide wire in position, the laser catheter is withdrawn from the patient and a balloon catheter is slid down the guide wire to the treatment site. The balloon catheter is inflated to dilate the remaining occluded area. When the catheter and guide wire are withdrawn, the previously occluded area remains dilated; thus, blood flow through the region is increased. U.S. Patent 4,854,315 to Stack et al. shows a laser catheter employing a related technique. In the Stack et al. device, a guide wire is used to position a first laser catheter near an intravascular obstruction. The first catheter is used to ablate a channel through the obstruction and to better position the device within the vessel. A second, larger catheter concentrically disposed on the first catheter is slide down the first catheter/guide wire assembly to the obstruction and continues the ablation process by eliminating the peripheral regions of the obstruction. In this manner, a level of blood flow comparable to that achieved through balloon dilation may be realized. However, the shape and nature of the vascular occlusion will not always permit a guide wire to be positioned so that a laser catheter can be accommodated for ablation. A total vascular occlusion may prevent a guide wire from crossing the occlusion. If the occlusion cannot be crossed by conventional techniques, such as dottering the wire through the occlusion, by-pass surgery is required to reestablish blood flow through the vessel. Though a laser catheter can ablate the occlusion and thus allow the surgical assembly to pass, its relatively large diameter prohibits adequate positioning within the vessel to perform the ablation process. Moreover, the large size of the guide wire/catheter combination may traumatize some vessels or otherwise limit the use of the device. SUMMARY OF THE INVENTION It is an object of this invention to provide a guide wire which is capable of delivering laser energy to intravascular areas. It is another object of the present invention to provide a guide wire capable of crossing total occlusions in blood vessels. It is yet another object of the present invention to provide a guide wire which can perform preliminary ablation for a laser catheter. It is still another object of the present invention to provide a laser ablation device that will not traumatize small vessels. It is a further object according to a preferred embodiment of the present invention to provide an exchange mechanism that permits a proximal coupler to be removed from a laser guide wire while the guide wire remains in place in a patient, thereby permitting the laser guide wire to be used as a conventional guide wire for a laser, balloon, or other type of catheter. It is another object of the present invention to provide a device for laser ablation which does not produce clinically significant perforations. The above objects are achieved by the features of the characterizing clause of claim 1. This guide wire apparatus has a solid tubular portion with a flexible body fixed to its distal end. The distal end of the body may be composed of a material more radiopaque than its proximal portion. Optical fibers are disposed within the assembly and terminate in a radiopaque tip at the distal end of the body. The guide wire may have a longitudinal marker wire for providing stiffness and radioscopic tracking characteristics. The guide wire has a proximal end attached to the tube and a distal end that also terminates in the tip. The invention may be maneuvered and positioned in a vascular area like a conventional guide wire. Then, laser energy from a laser light source at a proximal end of the guide wire is conveyed to the vascular area by the optical fibers to ablate an obstruction. Once the guide wire has ablated a passage in the obstruction, it may be placed in the passage and its proximal end severed from the proximal mount. The exchange mechanism may then be slid off the severed end to leave the guide wire portion. A larger catheter may then be slid over the guide wire to continue the ablation operation. Employing polyester for the distal body, the guide wire may be used in peripheral angioplasty applications. Alternatively, the distal body may be implemented with a metal coil and may be used in coronary angioplasty. BRIEF DESCRIPTION OF THE DRAWINGS These and other objects and advantages of this invention will become apparent and more readily appreciated from the following description of the presently preferred exemplary embodiments, taken in conjunction with the accompanying drawings, of which: FIGURE 1 is a perspective view of a fiber optic guide wire apparatus according to the present invention; FIGURE 2A is an enlarged longitudinal cross-sectional view of a guide wire tip according to a first embodiment of the present invention; FIGURE 2B is an enlarged axial cross-sectional view taken along the 2B-2B line of Figure 2A; FIGURE 3 is a perspective view of an exchange mechanism of a guide wire apparatus according to the present invention; FIGURE 4 is an enlarged longitudinal cross-sectional view of the exchange mechanism of Figure 3; FIGURE 5 is an enlarged longitudinal cross-sectional partial view of a guide wire tip according to a second embodiment of the present invention; FIGURE 6A is an enlarged partial longitudinal cross-sectional view of the guide wire tip according to a second embodiment of the present invention. FIGURE 6B is an enlarged axial cross-sectional view taken along the 6B-6B line of Figure 6A; and FIGURE 7 is an enlarged longitudinal partial cross-sectional view of a guide wire apparatus according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EXEMPLARY EMBODIMENTS FIGURE 1 depicts a perspective view of a fiber optic guide wire 10 according to the present invention. A proximal end 12 of a light conveying cable 14 is connected to a proximal mount 16 which can be coupled to a source of radiant energy. While any suitable coupling device may be used, the proximal mount described in United States Patent 5 321 783 to Nielson et al. is preferred for this purpose. The light conveying cable 14 is plastic tubing and has optical fibers disposed within, and these fibers are affixed to proximal mount 16 using techniques known in the art. A second end of light conveying cable 14 is attached to exchange mechanism 18, which will be described more fully herein. The distal side of exchange mechanism 18 is connected to guide wire assembly 20. The distal end of guide wire assembly 20 is terminated by tip 22, which will be described more fully herein. FIGURES 2A and 2B are cross-sectional views of a first embodiment of the guide wire assembly 22 of Figure 1. The internal structure of the guide wire assembly 22 is clearly illustrated in this drawing. Guide wire assembly 22 comprises optical fiber bundle 24 disposed within jacket 26. The bundle may comprise, for example, sixteen polyimide-buffered fibers each approximately 100 µm in diameter, and the jacket may be made from any suitable material; for example, a polyester copolymer tubing such as Hytrel 82D has proven to be advantageous in this application. Jacket 26 may additionally be coated with a suitable lubricant. An ultraviolet-curable hydrophilic coating manufactured by Bio-Metric Systems, Incorporated is advantageously employed for this purpose. The distal tip 22 of guide wire assembly 20 comprises marker band 28. Marker band 28 is advantageously made from a radiopaque material such as platinum-iridium and includes a proximal end 30 with a reduced outer diameter. The reduced outer diameter portion 30 of marker band 28 is disposed between jacket 26 and optical fiber bundle 24 and is bonded with these components using a suitable adhesive such as Loctite 454 in a manner more fully described below. The distal rim of marker band 28 may be beveled at an angle  to give the catheter tip a less traumatic profile, thus enabling the tip to pass through vascular channels more easily. A bevel angle  of sixty degrees from the face of the marker band has been found to provide good results. Also, a small area of the terminal face 36 of the optic fiber bundle 24 may also be beveled to provide a smooth transitional area. Longitudinal marker wire 32 also runs within jacket 26. A distal end of longitudinal marker wire 32 is attached to a proximal end of marker band 28. Like marker band 28, longitudinal marker wire 32 is fabricated from a radiopaque material such as platinum so that the distal tip 22 of guide wire assembly 20 will be easily detectable by radioscopic diagnostic techniques. Additionally, longitudinal marker wire 32 adds stiffness to the hypo tube to jacket transition to aid in tracking the guide wire through tortuous vascular passages. The proximal end of jacket 26 is bonded to the distal end of hypo tube 34. The proximal end of hypo tube 34 is coupled to exchange mechanism 18 Hypo tube 34 is preferably constructed of stainless steel. Longitudinal marker wire 32 extends through and is fixed to the proximal end of hypo tube 34. Thus, longitudinal marker wire 32 increases the structural integrity of the guide wire by providing a strong connection between marker band 28 and the remainder of the guide wire should marker band 28 accidentally become disengaged from jacket 26 and optical fiber bundle 24. It should be noted that the relative dimensions of the components of guide wire assembly 20 have been exaggerated for demonstration purposes. For peripheral angioplasty applications, jacket 26 is preferably approximately 8-12 cm in length, while hypo tube 34 preferably has a length of approximately 137 cm. Also, jacket 26 and hypo tube 34 preferably have an outer diameter of approximately 0,84 mm and an inner diameter of approximately 0,61 mm. As shown in FIGURE 3, a proximal end of hypo tube 34 is attached to a distal side of exchange mechanism 18. Hypo tube 34 having optical fiber bundle 24 disposed therein enters exchange mechanism 18 through cap 38 of a Tuohy-Borst connector. Light conveying cable 14 enters exchange mechanism 18 through body 40 of the Tuohy-Borst connector and is coupled to hypo tube 34 as described below. Marking 88 on the exterior surface of light conveying cable 12 indicates the proximal end of an exchange lead (not shown) as will be more fully described below. FIGURE 4 is a longitudinal cross-sectional view of exchange mechanism 18 which more clearly shows the coupling of hypo tube 34 to light conveying cable 14. Hypo tube 34 enters exchange mechanism 18 through a hole 72 in Tuohy-Borst connector cap 38. The proximal end of hypo tube 34 terminates within ring 74 (preferably a silicone ring), and the distal end of exchange lead 76 terminates within and is bonded to the proximal end of hypo tube 34. The proximal portion of exchange lead 76 exterior to ring 74 is encased by tail tubing 78 and extends approximately 100 cm on the proximal side of Tuohy-Borst body 40. Tail tubing 78 also serves as the exterior of light conveying cable 14. The distal end of tail tubing 78 is itself encased in two layers 80 and 82 of heat shrinkable material which serve as a strain relief for light conveying cable 14. Optical fiber bundle 24 runs through the central lumen formed by the hypo tube-exchange lead assembly. Ring 74 seats within Tuohy-Borst connector body 40 on a face 84 perpendicular to its longitudinal axis. Cap 38 fits on the distal end of body 40 by way of screw threads, for example. Cap 38 is fitted onto body 40 so that the proximal end of collar 86 of cap 38 presses against ring 74. Thus, ring 74 is compressed along its longitudinal axis, thereby maintaining the position of exchange mechanism 18 along hypo tube 34. The proximal end of tail tubing 78 and optical fiber bundle 24 extend beyond the proximal end of exchange lead 76 and terminate in proximal mount 16. Connection of tail tubing 78 and optical fiber bundle 24 may be accomplished using techniques disclosed in the above-referenced U.S. Patent 5321 783 to Nielson et al. The point along tail tubing 78 where exchange lead 76 terminates may be indicated with an appropriate marking 88 (FIGURE 3). Marking 88 is useful when using guide wire 10 to position a catheter as described below. A method of making a first embodiment of the present invention will now be described. First, hypo tube 34 must be prepared for assembly. Each end of a 0,84 mm (0.033") outer diameter, 0,71 mm (0.028") inner diameter, 138 cm length hypo tube is sanded flat using a 3 µm, 101.6mm (4") diameter sanding disc. Then, each end is reamed to 0,71 mm (0.028"). This may be accomplished by initially reaming the tube with a 0,69 mm (0.027") reamer and following up with a 0,71 mm (0.028") reamer to eliminate any burrs that may be produced in the reaming process. Each end is then tapered by evenly sanding it at an angle on a 0.3 µm, 101.6 mm (4') diameter sanding disc. In this tapering process, the outer diameter of the tube should be reduced by approximately 0,01 mm (0.0005") at the terminal face of the tube end. Then, the hypo tube should be rinsed by injecting isopropyl alcohol into one end of the tube and allowing the alcohol to flow out the other end. The alcohol may be injected into the lumen defined by the hypo tube with a 23g needle attached to a 3 cc syringe or a similar device. Finally, the tube should be dried by injecting a 2,758 ·10 5 N/m 2 (40 psi) air supply into one end of the hypo tube. When no alcohol is ejected from the other end of the tube with the escaping air, the interior of the tube has been cleaned. The exterior of the tube may then be cleaned by wiping it with a Kimwipe soaked in isopropyl alcohol. Next, jacket 26 is prepared. A length of 0,6858 x 0,8382 mm (0.027" x 0.033") Hytrel tubing is wiped with an isopropyl alcohol-soaked Kimwipe. The tubing is cut into 25 cm lengths and fitted on a 0,6096 mm (0.024") mandrel that has been deburred, cleaned and coated with Dow 360 silicone oil. Alternatively, a Teflon-coated mandrel may be used; in this case, the silicone oil is not necessary. Approximately 5 cm of tubing should extend beyond one end of the mandrel. The assembly is then placed in a hot box set to provide a 1,379 ·10 4 N/m 2 (2 psi) air supply at 287,78°C (550°F). While firmly holding the assembly, the portion of the tubing extending beyond the mandrel is tensioned with tweezers until it looses its elasticity. While maintaining tension on the tube, the assembly is then removed from the hot box and allowed to cool. After the tube is cooled, tension on the tube is released and the hytrel tubing is removed from the mandrel. The previously-tensioned portion of the tube is cut at an angle to facilitate the insertion of 5 mm of the tubing or more into one end of the prepared hypo tube. At this stage, the outer diameter of the necked portion (i.e., the proximal end) should be approximately 0,69 mm (0.027") or 0,7 mm (0.0275"). The exterior of the tube is then wiped with an alcohol-soaked Kimwipe to remove any excess silicone oil. A razor blade is used to make a perpendicular cut on the distal end of the tube to give the tube a total length of between 8.0 cm and 12.0 cm. Next, longitudinal marker wire 32 and marker band 28 are prepared. A length of 0,08 mm (0.003") diameter, 90% platinum - 10% nickel wire is flattened using a conventional wire flattener. While taking care not to kink the flattened wire, it is cut into 155 cm lengths and set aside for later use. Marker band 28 is placed in a 100 ml beaker filled with acetone, and the beaker is placed in an ultrasonic bath. Using the cleaner, the bath is agitated for two minutes to clean marker band 28. Marker band 28 is then removed from the bath and wiped with a dry Kimwipe. Next, exchange lead 76 is prepared. A cleaned, deburred 0,69 mm (0.024")outer diameter x 30,4 mm (1') length mandrel is wiped with a Kimwipe soaked in silicone oil. Alternatively, a Teflon-coated mandrel may be used; in this case, the silicone oil is unnecessary. A 60,9 mm (2') length of Hytrel tubing is cut into 15 cm lengths and an end of one of the cuttings is placed over the mandrel so that approximately 50,8 mm (2") of the tube extends beyond the mandrel. A hot box is then used to form the tubing to the mandrel in a process similar to that in the jacket fabrication described above. When the assembly is removed from the hot box, the mandrel is partially pulled out of the tubing and the tubing is cut to provide a square tapered end of approximately 1 cm fitting on the mandrel. This process will form the proximal end of exchange lead 76. The distal end of exchange lead 76 is prepared in a similar manner; however, as with jacket 26, the distal end of exchange lead 76 is cut at an angle to facilitate insertion into hypo tube 34. Once the distal end of exchange lead 76 has been prepared, the mandrel is removed and exchange lead 76 is wiped with an alcohol-soaked Kimwipe. Next, tail tubing 78 and the Tuohy-Borst connector assembly are fabricated. A 9F Tuohy-Borst body 40 and cap 38 are placed in an isopropyl alcohol bath and ultrasonically cleaned in a manner similar to marker band 28 as described above. The body 40 and cap 38 are then removed from the bath and wiped with a dry Kimwipe. Advantageously, air may be blown on the parts to speed the drying process. A length of Raychem RNF 100 3/32" shrink tubing is cut into a 2 cm and a 2.5 cm length and similarly cleaned in an isopropyl alcohol bath. An 2,235m (88") length of Hytrel 82D tubing having an outer diameter of 1,47 mm (0.058") and an inner diameter of 0,97 mm (0.038") is wiped with an alcohol-soaked Kimwipe. Δ 0,91 mm (0.036")⊘ teflon coated mandrel is inserted into the tail tube. The 2.5 cm shrink tube 82 is placed on one end of tail tube 78 and heat is applied to fix shrink tubing 82 on tail tube 78. The 2 cm shrink tube 80 is similarly shrunk onto the 2.5 cm length 82. The shrink tubes are then wiped with an alcohol-soaked Kimwipe and allowed to dry. A 6,35 mm (0.25") outer diameter, 1,32 mm (0.052") inner diameter, 0,35 mm (0.25")wide silicone ring 74 is placed in Tuohy-Borst connector body 40 and cap 38 is then snapped and screwed onto body 40. A ring of EP30HT masterbond epoxy is deposited around the edge of shrink tube 80 and the end of the shrink tube/tail tube assembly is inserted into connector body 40 with a twisting motion to spread the epoxy along the interior surfaces of the connector body 40 contacting shrink tubing 80. The assembly is then allowed to cure for approximately four hours by hanging it with tail tubing 76 toward the floor. Next, optical fiber bundle 24 is formed. Sixteen spools of 100 µm diameter optical fibers are loaded on a fiber pulling rack. Approximately four meters of fibers are pulled from the rack along a clean, planar surface such as a table top that has been wiped with alcohol-soaked Kimwipes. The fibers are then cut from the pulling rack using a cutting stone. The above-described components are then assembled together to form the laser guide wire. First, optical fiber bundle 24 is inserted into the proximal end of hypo tube 34. Approximately 20 cm of the fibers should extend beyond the distal end of hypo tube 34. This portion of the fibers is inserted into the proximal end of jacket 26 so that approximately 5 cm of the fibers extend beyond the distal end of jacket 26. Longitudinal marker wire 32 is inserted into the distal end of jacket 26 until the proximal end of wire 32 appears at the proximal end of jacket 26 and then positioned so that approximately 1 cm of longitudinal marker wire 32 extends beyond the distal end of jacket 26. The marker wire is inserted into the hypo tube until it extends out of the proximal end of the hypo tube. Then the jacket is inserted into the hypo tube. The jacket/marker wire assembly is then moved toward hypo tube 34 so that the marker wire 32 and the proximal end of jacket 26 are inserted into hypo tube 34. Marker wire 32 should be substantially parallel to the longitudinal axis of the hypo tube/jacket assembly with no twists. Jacket 26 is then retracted from hypo tube 34, wiped with an alcohol-soaked Kimwipe and its proximal end is coated with Masterbond epoxy and reinserted into hypo tube 34. Excess epoxy is wiped away with a dry Kimwipe, and the assembly is cured for approximately four hours. The proximal end of longitudinal marker wire 32 extending beyond the proximal end of hypo tube 34 is then bent over hypo tube 34. Exchange lead 76 is then slid over the proximal end of optical fiber bundle 24 so that the proximal portion of longitudinal marker wire 32 is sandwiched between the exterior of the angled, tapered end of exchange lead 76 and the interior surface of hypo tube 34. Exchange lead 76 is backed out of hypo tube 34, and exchange lead 76 and the end of hypo tube 34 are wiped with an alcohol-soaked Kimwipe. A ring of Masterbond epoxy is deposited on the end of exchange lead 76 and it is reinserted into hypo tube 76. Excess epoxy is wiped away with a dry Kimwipe, and the bent portion of longitudinal marker wire 32 is removed with wire cutters or repeated flexing so that no stub projects from the assembly. The assembly is then cured for four hours. Curing of the exchange lead/hypo tube bond may be performed concurrently with curing of the jacket/hypo tube bond to speed the fabrication process. The distal end of longitudinal marker wire 32 is trimmed so it extends only 1 mm beyond the distal end of jacket 26, and the 1 mm end of the marker wire is fitted on the reduced diameter of the marker band 28. Reduced outer diameter portion 30 is coated with Loctite 454 gel and inserted into the lumen defined by jacket 26 so that it is sandwiched between the exterior of optical fiber bundle 24 and the interior surface of jacket 26. The assembly is cured for approximately two minutes, and excess adhesive is removed with Loctite solvent. The distal end of optical fiber bundle 24 may then be potted, beveled and polished using techniques known in the art. An advantageous method is described in United States Patent 5 263 952 to Grace et al. The proximal end of fiber bundle 24 is inserted into cap 38 of the Tuohy-Borst connector, the Tuohy-Borst assembly is moved distally and then tightened over the hypo tube/distal exchange section. The proximal ends of tail tube 78 and optical fiber bundle 24 may be connected to proximal mount 16 as described in the above-referenced US-Patent 5 321 783 to Nielson et al. Exchange mechanism 18 may be advantageously used to ablate an intravascular occlusion and then to position a catheter for subsequent occlusion. In this technique, guide wire 10 is connected to a source of light energy such as a laser by way of proximal mount 16. Guide wire assembly 20 is partially inserted into a patient using conventional surgical techniques and positioned so tip 22 is proximate to the occlusion. Energy transmitted from the source along optical fiber bundle 24 to tip 22 may then be used to ablate a channel through the occlusion. Once a channel has been formed in the occlusion, tip 22 is positioned within the channel. Light conveying cable 12 is severed where marking 88 indicates the termination of exchange lead 76. Tuohy-Borst cap 38 is disengaged from body 40, and both pieces are slid off the proximal end with tail tube 78 and shrink tubes 80 and 82. The proximal end of newly-severed optical fiber bundle 24 is pulled away from exchange lead 76 and then cut so that bundle 24 retracts inside exchange lead 76. Then, a catheter may be placed on the proximal end of exchange lead 76 and slid down to the entry point of hypo tube 34 in the patient's body. The catheter is then introduced into the patient's body and slid along hypo tube 34 until it is proximate to the partially-ablated occlusion. With this procedure, a laser catheter may be used to ablate a larger area of the occlusion. A balloon catheter may be used to dilate the vascular area having the occlusion instead of a laser catheter. FIGURE 5 is a partial longitudinal cross-sectional view of a second embodiment of the guide wire assembly 10 of Figure 1. From hypo tube 34 in the proximal direction, this embodiment is the same as that described relative to Figures 3 and 4. However, this embodiment differs from the previous embodiment distal to hypo tube 34. In Figure 5, optical fiber bundle 24 has been removed to more clearly show the internal structure of guide wire assembly 20. Instead of using a polyimide copolymer jacket on the distal end of hypo tube 34, this embodiment employs helical, radiopaque coil 68 to form the distal end of guide wire assembly 20. Hypo tube 34 includes an intermediate tapered portion 42 connected to a reduced diameter portion 44 on its distal end. Hypo tube 34 is preferably constructed from stainless steel and, proximal to tapered portion 42, has an outer diameter of approximately 0,46 mm (0.018 in). and an inner diameter of approximately 0,33 mm (0.013 in). Coil 68 has a proximal end covering and connected to the reduced diameter portion 44 of hypo tube 34 and a distal end which is fixed to marker band 28. Coil 68 is preferably fabricated from a radiopaque material such as platinum so the guide wire may be tracked using radioscopic techniques as described above. Coil 68 has a proximal compressed portion 52 and a distal expanded portion 54. By stretching distal expanded portion 54 of coil 68, the distal end of guide wire assembly 22 can better track vascular contours while compressed portion 52 provides rigidity to the structure. It has been found that a coil fabricated from a 90% platinum - 10% nickel alloy having a diameter of 0,06 mm (0.0025 in). is suitable for this purpose and additionally provides desirable flexibility, torquability and pushability characteristics. Preferably, expanded portion 54 of coil 68 is approximately 3 cm in length, while compressed portion 52 of coil 68 is approximately 27 cm in length. Also, marker band 28 is preferably fabricated from a 90% platinum - 10% iridium alloy and has an outer diameter of approximately 0,46 mm (0.018 in.), an inner diameter of approximately 0,33 mm (0.013 in.), and a length of approximately 2 mm. Mandrel 70 is mounted on an inner surface of reduced diameter portion 44 of hypo tube 34 and provides additional rigidity, torquability and pushability to guide wire assembly 20. Mandrel 70 has a proximal portion 46 eccentrically soldered or epoxied to hypo tube 34 and an intermediate portion 48 which tapers down to a flattened portion 50 at its distal end. Mandrel 70 is angled so that the distal end of flattened portion 50 is substantially central to and coterminal with terminal face 36. Preferably, mandrel 70 is fabricated from stainless steel, with the proximal portion 46 thereof having a diameter of approximately 0,13 mm (0.005 in.) and a length of approximately 15 cm, the intermediate tapered portion 48 thereof having a length of approximately 10 cm, and the flattened portion 50 thereof having a width of approximately 0,15 mm (0.006 in.), a thickness of approximately 0,65 mm (0.002 in.) and a length of approximately 3 cm. Also, hypo tube 34 may be coated to provide a low-friction surface for improved guide wire maneuverability characteristics. A suitable coating for this purpose is Teflon®. FIGURES 6A and 6B are cross-sectional views of the second embodiment of the invention showing the placement of optical fiber bundle 24. Optical fiber bundle 24 emerges from reduced diameter portion 44 of hypo tube 34 and extends to terminate at the distal end of a glue plug 62 in marker band 28. In this embodiment, optical fiber bundle 24 is preferably comprised of a bundle of approximately 14 polyimide-buffered optical fibers each having a diameter of 45 µm. The proximal end of coil 68 is attached to hypo tube 34 by solder or epoxy joint 56. Similarly, a solder or epoxy joint 60 is used to attach the distal end of coil 68 to marker band 28. A central solder or epoxy joint 58 bonds the interface between compressed portion 52 and expanded portion 54 of coil 68 to mandrel 70. While the first two of the above-mentioned joints are annular in shape, central joint 58 is essentially disk-shaped, since the epoxy or molten solder tends to flow between cracks in the coil turns and wick throughout the optical fiber bundle 24 in that region. A method of making the second embodiment of the present invention will now be described. First, coil 68 is formed and its distal portion is stretched approximately 50% to form expanded portion 54, while the remainder of coil 68 forms compressed portion 52. Proximal portion 46 of mandrel 70 is soldered or epoxied to reduced diameter portion 44 of hypo tube 34. Then, the proximal end of coil 68 is fitted over the reduced diameter portion 44 and soldered or epoxied thereto. Marker band 28 is f soldered or epoxied onto the distal end of coil 68. Optical fiber bundle 24 is inserted into the jacket/hypo tube assembly so that its distal end protrudes from marker band 28. Coil interface solder or epoxy joint 58 is then formed by flowing solder or epoxy at the transition between the compressed portion 52 and the expanded portion 54 of coil 68 and into optical fiber bundle 24 to bond with mandrel 70. Finally, a suitable adhesive is wicked up the distal end of optical fiber bundle 24 to form glue plug 62 within marker band 28 and terminal face 36 is polished to provide an optically smooth surface. Also, the periphery of terminal face 36 may be bevelled as described above. After the distal end of guide wire assembly 20 has thus been fabricated, the remainder of the device may be constructed in a manner similar to the one previously described in the construction of the first embodiment of the present invention. It has been found that a guide wire according to the second embodiment of the present invention is particularly well-suited to applications such as coronary angioplasty. In such applications, hypo tube 34 and coil 68 are together preferably approximately 175 cm long. Thus, hypo tube 34 in this embodiment is longer than that of the first embodiment, which is preferably used in peripheral angioplasty applications. Since both techniques generally introduce the guide wire into the patient's body at the groin area, additional length is required in the coronary version to reach the more distantly located vessels near the heart. FIGURE 7 depicts a portion of a third embodiment of the present invention. In this Figure, hypo tube 134 is shortened to provide a small fitting for connecting coil 68 to jacket 64, which substantially replaces hypo tube 34 in the second embodiment. Construction of this embodiment is similar to that of the second embodiment; however, the proximal end of hypo tube 134 is attached to jacket 64 with a suitable adhesive such as cyanoacrylate, and the proximal end of jacket 64 is attached to exchange mechanism 18.

Claims: A fiber optic guide wire apparatus for intravascular angioplasty comprising: a hollow guide wire assembly (20), an optical fiber bundle (24) disposed within said guide wire assembly and means for introducing light energy into a proximal end of said optical fiber bundle, characterized in that the hollow guide wire assembly (20) comprises a solid tubular portion with a flexible body fixed to its distal end which are formed by a hypo tube (34) and a hollow outer jacket or coil (26, 68), said hollow outer jacket or coil having a proximal end connected to a distal end of said hypo tube, said hollow guide wire assembly having a distal end termination; a plug (62) is disposed at a distal end of said hollow guide wire assembly and has a distal face flush with said distal end termination of said hollow guide wire assembly; said optical fiber bundle (24) is disposed within said guide wire assembly and includes a plurality of optical fibers, said optical fiber bundle extending through said plug and having a distal face terminating at said distal face of said plug, said plug surrounding said optical fibers in said bundle and bonding said fibers to said distal end of said hollow guide wire assembly; a mandrel (70) is disposed within said guide wire assembly and has a distal end terminating at said distal end of said guide wire; an exchange lead (76) has a distal end connected to proximal end of said hypo tube; said exchange lead extending proximally from said hypo tube for sliding a catheter along said guide wire. The fiber optic guide wire apparatus of claim 1, characterized in that said mandrel comprises: a base portion (46) at said proximal end; and a flattened portion (50) at said distal end. The fiber optic guide wire apparatus of claim 1, characterized in that said outer jacket comprises a wire coil (68). The fiber optic guide wire apparatus of claim 3, characterized in that said wire coil has a compressed portion (52) at a proximal end thereof and an expanded portion (54) at a distal end thereof. The fiber optic guide wire apparatus of claim 3, characterized in that said wire coil further comprises an intermediate joint (58) for fixing a proximal end of said expanded portion, a distal end of said compressed portion, and said mandrel in place relative to one another. The fiber optic guide wire apparatus of claim 1, characterized in that a distal tip (22) of said guide wire assembly comprises a marker band (28). The fiber optic guide wire apparatus of claim 6, characterized in that a marker wire (32) disposed within said guide wire assembly, a proximal end of said marker wire is connected to said hypo tube and a distal end of said marker wire is connected to said marker band. The fiber optic guide wire apparatus of claim 1, characterized in that the hypo tube (34) having the optical fiber bundle (24) disposed therein extends through a cap (38) of a Tuohy-Borst connector and said means for introducing light energy (14) extends through a body of the Tuohy-Borst connector and is coupled to the hypo tube. The fiber optic guide wire apparatus of claim 8, characterized in that a tail tube (78) is provided, having a distal end covering at least a proximal end of said exchange lead (76) and a proximal end connected to said means for introducing light energy (14). The fiber optic guide wire apparatus of claim 1, characterized in that it further comprises: a shrink tube (80, 82) disposed on said optical fiber bundle proximal to a proximal end of said exchange lead (76); whereby said shrink tube maintains fibers in said optical fiber bundle together when said optical fiber bundle is severed between said shrink tube and said proximal end of said exchange lead.

Inventors: HILLSMAN CECILY M, KASPRZYK DANIEL J, SOLAR MATTHEW S, HILLSMAN, CECILY M., KASPRZYK, DANIEL J., SOLAR, MATTHEW S.
Applicants: SPECTRANETICS CORP, THE SPECTRANETICS CORPORATION
Application year: 1993
Main classification: A61M25
IPC codes: A61M25, A61B17, A61B18, A61N5, A61L29, A61L27, A61B19