Infrared Laser Catheter Apparatus

~" ' MM II II II Ml II I II III II II II I II J European Patent Office © Publication number: 0 214 712 B1 Office_„. europeen- desj ^brevets »

@ Date of filing: 27.05.86

® Priority: 31.07.85 US 761188 © Proprietor: C.R. BARD, INC. 731 Central Avenue @ Date of publication of application: Murray Hill New Jersey 07974(US) 18.03.87 Bulletin 87/12 @ Inventor: Slnofsky, Edward © Publication of the grant of the patent: Apartment 8 South Washington Street 02.09.92 Bulletin 92/36 Reading Massachusetts(US)

© Designated Contracting States: DE FR GB IT NL © Representative: Woodward, John Calvin et al VENNER SHIPLEY & CO. 368 City Road © References cited: London EC1V 2QA(GB) EP-A- 0 153 847 GB-A- 2 017 506 GB-A- 2 125 986 US-A- 3 327 712 US-A- 4 383 729 US-A- 4 458 683

ELECTRONIC DESIGN, vol. 17, no. 13, June 21, 1969, pp 36, 38, 40 D.N. KAYE: "The happy merger of fiber optics and lasers"

00 CM

O Note: Within nine months from the publication of the mention of the grant of the European patent, any person ^ may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition qj shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid (Art. 99(1) European patent convention). Rank Xerox (UK) Business Services 1 EP 0 214 712 B1 2

Description laser is very short, typically about ten nanoseconds. In order to develop reasonable aver- This invention relates to a laser catheter ap- age power, pulses with extremely high peak power paratus for generating and transmitting energy to a must be used. When an attempt is made to chan- surgical site in a living body for the purposes of 5 nel such a high peak power output into an optical tissue removal or repair. fiber, the high peak power destroys the fiber. Thus, While lasers have been used for many years excimer lasers have a practical power limit which is for industrial purposes such as drilling and cutting relatively low. Consequently, when these lasers are materials, it is only recently that surgeons have used for biological tissue removal, the operation is begin to use lasers for surgical operations on living 10 slow and time consuming. tissue. To this end, laser energy has been used to The CO2 laser has other drawbacks. This laser repair retinal tissue and to cauterize blood vessels generates output energy with a wavelength on the in the stomach and colon. order of 10 micrometers. At this wavelength, the In many surgical situations, it is desirable to absorption of blood hemoglobin is negligible but transmit laser energy down an optical fiber to the 15 the absorption by water and tissue is relatively surgical location. If this can be done, the optical high. Scattering at this wavelength is also very low. fiber can be included in a catheter which can be Although the CO2 laser possesses favorable char- inserted into the body through a small opening, acteristics for surgical applications in that it has low thus reducing the surgical trauma associated with scattering and high absorption in tissue, it suffers the operation. In addition, the catheter can often be 20 from the same drawback as excimer lasers in that maneuvered to surgical sites which are so restrict- the absorption length is relatively short due to the ed that conventional scalpel surgery is difficult, if high absorption of the laser energy in water. Thus, not impossible. For example, laser energy can be the surgical area must be cleared of blood prior to used to remove atherosclerotic plaque from the the operation. walls of the vasculature and to repair defects in 25 Unfortunately, the CO2 laser also suffers from a small-diameter artery walls. serious additional problem. Due to the long A problem has been encountered with laser wavelength, the output energy from the carbon surgery in that prior art lasers which have been dioxide laser cannot be presently transmitted down used for industrial purposes often have characteris- any optical fibres which are suitable for use in tics which are not well suited to percutaneous laser 30 percutaneous surgery (present fibres which can surgery. For example, a laser which is convention- transmit energy from a CO2 laser are either com- ally used for scientific purposes is an excimer laser posed of toxic materials, are soluble in water or are which is a gas laser that operates with a gas not readily bendable, or possess a combination of mixture such as Argon-Fluorine, Krypton-Fluorine the previous problems) and, thus, the laser is only or Xenon-Fluorine. Another common industrial laser 35 suitable for operations in which the laser energy is the carbon dioxide or CO2 laser. can be either applied directly to the surgical area Both the excimer laser and the CO2 laser have or applied by means of an optical system com- been used for surgical purposes with varying re- prised of prisms or mirrors. sults. One problem with excimer lasers is that they David N. Kaye describes in his article "The produce output energy having a wavelength in the 40 happy merger of fibre optics and lasers" two meth- range 0.2-0.5 micrometers. Blood hemoglobin and ods of combining fibre optics and lasers as a tool proteins have a relatively high absorption of energy to reach locations which are not accessible with in this wavelength range and, thus, the output large fixed lasers. Among several laser/fibre com- beam of an excimer laser has a very short absorp- binations an Er:Glass laser for medical and indus- tion length in these materials (the absorption length 45 trial use is proposed. This laser emits a pulsed is the distance in the materials over which the laser radiation of 1 .54 urn so as to eliminate retinal eye beam can travel before most of the energy is damage. Most of the lasers described operate in absorbed). Consequently, the surgical site in which continuous wave mode so they cannot be used for these lasers are to be used must be cleared of the successful removal of plaque. References are blood prior to the operation, otherwise most of the 50 also made to several materials which can be made laser energy will be absorbed by intervening blood to lase at various wavelengths but the only use of before it reaches the surgical area. While the re- the equipment described is for the treatment of the moval of blood is possible if surgery is performed eye rather than for plaque removal deep within the on an open area it is often difficult if surgery is to body. Indeed, none of the equipment described be performed via a catheter located in an artery or 55 could be used for this purpose. vein. GB-A-2017506 discloses a laser tunnelling de- An additional problem with excimer lasers is vice in which a thrombus in a blood vessel is that the output energy pulse developed by the destroyed by the use of laser light fed through an

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optical fibre received in a catheter inserted into a tromagnetic energy scattering versus blood vessel. However, there is no discussion or wavelength. suggestion in this reference that atherosclerotic Figure 2 shows an absorption versus wavelength plaque could be removed by this method, and plot for atherosclerotic plaque obtained in a ca- there is no suggestion of the parameters required 5 rotid endarterectomy with the region of interest to achieve such plaque removal. for the inventive laser sources (1.4-2.2 microm- It is an object of the present invention to pro- eters) outlined. vide a laser catheter which is capable of providing Figure 3 of the drawing is a schematic diagram laser energy that can be transmitted through an of a typical solid state laser construction used in optical fibre under such conditions as to achieve io the inventive laser sources. plaque removal. Figure 4 of the drawing is a plot of laser output In accordance with the present invention there intnsity versus time for a typical pulse shape is provided a laser catheter apparatus for surgically developed by a laser shown in Figure 3 when removing atherosclerotic plaque from a surgical used for tissue removal. site within the body, comprising a flexible catheter is Figure 5 is a schematic diagram of a laser member, a laser energy source and an optical fibre catheter which employs a single optical fiber for located within a lumen defined within the catheter transmitting laser energy to a surgical location. member, the optical fibre being composed of a Figure 6 of the drawing is an enlarged cross- substantially non-toxic material and being tolerant section of the probe tip the single fiber catheter to the operation of the laser source, wherein the 20 shown in Figure 5. output of the laser source is directed into the Figure 7 of the drawing shows the manner in proximal end of the optical fibre, propagated along which the fiber is inserted into the fiber holder. the optical fibre, and is directable by means at- Figure 8 is a schematic diagram of a wire- tached to the distal end of the optical fibre to the guided catheter which employs four optical fi- surgical site, the catheter member and optical fibre 25 bers to increase the area which can be irradi- being sufficiently flexible and being dimensioned to ated with the laser light. be passed from without the body, into and along a Figure 9 and 10 of the drawing show an en- vein or artery, to the surgical site, characterised in larged cross-sectional view of the probe tip of that the laser source operates in a pulsed mode the catheter shown in Figure 8 showing the four with pulses of a duration in a range of 0.2-5 mil- 30 optical fibers. liseconds and a wavelength range of 1.4-2.2u.m Figure 1 1 of the drawing is a schematic diagram whereby to provide an effective removal of ar- of the beam pattern produced by the four-fiber- therosclerotic plaque. catheter at the surgical location. Illustrative laser sources operating in the The absorption and scattering characteristics wavelength range of 1.4-2.2 micrometers are 35 versus output wavelength of a plurality of known Holmium-doped YAG, Holmium-doped YLF, laser systems are shown in Figure 1 . Figure 1 has Erbium-doped YAG, Erbium-doped YLF and a logarithmic scale respresenting the absorption Thulium-doped YAG lasers. coefficient in units of cm-1 along the vertical axis Preferably, the above-noted lasers are used and the incident energy wavelength in micrometers with a specially-treated silica fibre that has been 40 along the horizontal axis. purified to reduce the concentration of hydroxyl From Figure 1, it can be seen that excimer (OH-) ions. laser systems which utilize conventional gas mix- The laser source is preferably operated such tures, such as Argon-Fluorine, Krypton-Fluorine and that the peak power of the laser pulse is approxi- Xenon-Fluorine, and Argon gas lasers produce out- mately 1 kilowatt. This amount of power can easily 45 put energy which falls in the 0.2-0.5 micrometer be tolerated by the silica fibre, but is sufficient for wavelength region. In this region, the absorption of rapid material removal. With a repetition rate in the blood hemoglobin and proteins is very high. Con- range of 1-10 hertz, the average power delivered to sequently, the absorption length is very short a surgical site by such a laser will be under 10 (about 5-10 microns) and virtually no blood can be watts. 50 present between the fiber end and the surgical site Preferred aspects and embodiments of the in- during the operation. Thus, it is necessary to re- vention are defined and described in the depen- move blood from the surgical area when these dent claims 2-1 1 , attached hereto. lasers are used for surgical purposes. The invention will now be described, by way of In addition, for lasers such as Argon, the ab- example only, with reference to the accompanying 55 sorption of water reaches a minimum at 0.5 mi- drawings, in which : crometers so that it is necessary to use a higher Figure 1 shows a sketch of absorption of elec- power laser than is desirable to achieve sufficient tromagnetic energy versus wavelength and elec- power in the surgical area for material cutting and

3 5 EP 0 214 712 B1 6 removal. Also, due to the low absorption of the wavelength range and generally increases with in- laser output in water and hemoglobin, the absorp- creasing wavelength in the wavelength region of 1- tion length is very long (approximately 1 mm). In 2.2 micrometers. addition, scattering for these lasers is relatively In the wavelength range from 1.4-2.2 microm- high, causing difficulty in controlling the laser en- 5 eters, the wavelength range produced by laser in ergy and a danger of tissue damage outside the the above-mentioned group, the absorption by surgical area due to scattering of the laser energy. plaque is at a relatively high value. At the other end of the wavelength spectrum A schematic diagram of a typical solid-state shown in Figure 1 are carbon monoxide and carbon laser construction is shown in Figure 3. The laser dioxide lasers producing outputs at 5 and 10 mi- 10 assembly consists of a laser crystal 1 and an crometers, respectively. At these wavelengths scat- excitation device such as a flashlamp 3. Typically, tering is negligible and absorption by water and for the crystal compositions disclosed above, the tissue is relatively high and thus both lasers have laser crystal must be cooled to cryogenic tempera- good surgical properties. Unfortunately, due to the ture to provide low laser-threshhold operation. high absorption of water, the absorption length is 15 Cryogenic cooling is typically provided by enclos- relatively short (about 20 microns). Further, silica- ing crystal 1 in a quartz or fused-silica jacket 4 based optical fibers in present use which are suit- through which liquid nitrogen is circulated. Liquid able for percutaneous surgical use have a practical nitrogen enters jacket 4 by means of an inlet pipe "cutoff" in transmission which occurs approximate- 5 and leaves by means of an outlet pipe 6. The ly at 2.3 micrometers, and, thus, the output energy 20 laser cavity is formed by a high-reflectivity concave from carbon monoxide and carbon dioxide lasers mirror 10 and a partial reflector 12. cannot be transmitted through such an optical fiber. Generally, the crystal is excited by optical In accordance with the invention, laser sources pumping which is, in turn, accomplished by irra- of interest are those that lie in the wavelength diating the crystal with light from a flashlamp 3. A range of approximately 1.4-2.2 micrometers. As 25 flashlamp which is typically used with the inventive shown in Figure 1, in this range, the energy ab- laser compositions is a high pressure Xenon flash- sorption of water is relatively high whereas optical lamp. Lamp 3 may also be surrounded by a quartz scattering is relatively low. Illustrative lasers which flow tube (not shown) through which coolant is are useful with the present invention comprise pumped. Erbium-doped Yttrium Aluminum Garnet (YAG) with 30 Crystal 1 and flashlamp 3 are enclosed in a a wavelength of 1.55 micrometers, Erbium-doped reflector 2 which concentrates the flashlamp en- Yttrium Lithium Fluoride (YLF) with a wavelength of ergy into the laser crystal. To maximize energy 1.73 micrometers, Thulium-doped YAG with a transfer from lamp 3 to crystal 1 , the inner surface wavelength of 1 .88 micrometers, Holmium YLF with of reflector 2 is coated with a material chosen to a wavelength of 2.06 micrometers and Holmium 35 have high-reflectivity at the pumping wavelength of YAG at a wavelength of 2.1 micrometers. The ab- the laser crystal - illustratively, aluminum or silver. sorption of the laser energy produced by lasers in In order to provide thermal insulation to prevent this latter group by water is moderately high and, condensation on the system optics, it may be nec- consequently, the absorption by biological tissues essary to evacuate the interior of reflector 2 or to of such energy will also be relatively high. How- 40 provide a vacuum jacket around crystal 1 . ever, the absorption by water is not as high as the The construction of cryogenic solid-state lasers absorption of CO and CO2 laser energy. Thus, the is conventional and described in a variety of sour- absorption length will be longer for the lasers op- ces; accordingly such construction will not be dis- erating in the 1.4-2.2 micron range. Typically, the cussed further in detail herein. A more complete absorption length in the body for these latter lasers 45 discussion of construction details of a typical cryo- is about 200 microns. Therefore, it is still possible genic laser is set forth in an article entitled "TEMoo to operate satisfactorily even with 10-30 microns of Mode Ho:YLF laser", N.P. Barnes, D.J. Gettemy, blood between the fiber end and the surgical site. N.J. Levinos and J.E. Griggs, Society of Photo- Of particular interest is the absorption of the Optical Instrumentation Engineers, Volume 190 - laser energy by atherosclerotic plaque, since an 50 LASL Conference on Optics 1979, pp 297-304. important use of laser catheter systems is an- Figure 4 of the drawing is a plot of the illustra- gioplasty, particularly the clearing of blocked ar- tive pulse shape developed by a laser in the pre- teries. Figure 2 is a plot of the absorption by ferred group when used in the "material removal" plaque of electromagnetic energy versus mode. Figure 4 shows light intensity along the wavelength for energy in the wavelength range of 55 vertical axis increasing in the downward direction 0.2-2.2 micrometers. As shown in Figure 2, the versus time increasing towards the right. Although, absorption by plaque of electromagnetic energy as shown in Figure 4, the laser source has been reaches a minimum in the 0.8-1 micrometer adjusted to produce an output pulse of relatively

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long time duration, most of the output energy is the surgical area is visible to the surgeon, the light released within approximately 1 millisecond of the produced by laser 20 passes through the optical beginning of the pulse. It should also be noted.as fiber in catheter 30 and can be used to aim the illustrated in Figure 4, that lasers in the preferred probe tip before laser 21 is turned on to perform laser group exhibit a "spiking" phenomenon caus- 5 the actual operation ed by internal relaxation-oscillations in the laser The second lumen in catheter 30 is provided crystal. The spiking behavior causes local in- for transmission of a flushing fluid or to apply creases in laser intensity which have a large mag- suction to the probe lens tip area to clear the area nitude, but a very short time duration. Similar of blood during surgery. This latter lumen is con- "spiking" behavior has been found advantageous io nected through bifurcation fitting 28 to a second when lasers are used to drill metals and other tube 29. Tube 29 may illustratively be terminated materials for industrial purposes and it is believed by a standard Luer-Lok fitting 26 which allows that such "spiking" behavior enhances the laser connection of the catheter to injectors and standard usefulness for biological material removal. flow fittings. Solutions injected into the catheter Figure 5 is a schematic diagram of a is through tube 29 pass through the lumen in catheter laser/catheter apparatus employing a solid state 30 and exit at the distal end via a small orifice 32. laser of the type shown in detail in Figure 3. More Probe tip 34 consists of a lens arrangement specifically, the infrared output energy of laser 21 which forms the laser energy into a beam 36 which is focused by a conventional focusing lens onto the is used to perform the surgical operations. An end of the optical fiber which is held in a conven- 20 enlarged view of the probe tip is shown in Figures tional fiber optic connector 24. Fiber optic connec- 6 and 7. tor 24 is, in turn, connected to a tube 27 which To ensure that the distal end of optical fiber 18 houses a single optical fiber. Tube 27 is connected is spaced and oriented in a precise position with to a conventional two-lumen catheter 30 by means respect to the end of the probe, fiber 18 is moun- of a bifurcation fitting 28. 25 ted in a high-precision holder 58 which has a Illustratively, catheter 30 has two lumens pass- reduced diameter end 64 that forms a shoulder 68. ing axially therethrough to its distal end 34 so that Shoulder 68, as will hereinafter be described, is an optical fiber can pass through one lumen and used to hold the probe tip assembly together. transmit laser energy from fiber optic connector 24 Holder 58 has a precision-formed axial bore made to lens tip 34. As previously mentioned, the optical 30 up of two sections, including a large-diameter sec- fiber which passes through the catheter is specially tion 60 and a narrow-diameter section 63. Holder purified to reduce the hydroxyl ion concentration to 58 may be made of glass, ceramic or other ma- a low level, thus preventing the laser energy which terial capable of being formed to specified dimen- is transmitted down the fiber from being highly sions with precise tolerances. absorbed in the fiber material. A fiber which is 35 In order to attach holder 58 to the end of fiber suitable for use with the illustrative embodiment is 18, the fiber is first prepared as shown in Figure 7. a fused-silica optical fiber part no. 822W manufac- More particularly, prior to insertion of fiber 18 into tured by the Spectran Corporation located in Stur- holder 58, a portion of buffer sheath 61 is removed, bridge, Massachusetts. exposing a length of optically-conductive core 65. Advantageously, the mirrors and lenses (10, 12 40 Care is taken when stripping buffer sheath 61 from and 22) which are used to form the IR laser cavity the fiber not to damage the layer of reflective and focus the output energy beam are generally cladding 67 located on the surface of core 65. After only reflective to energy with a wavelength falling stripping, fiber 18 is inserted into holder 58 so that within a narrow wavelength band and transparent to core 65 extends into the small-diameter bore 63 energy at other wavelengths. Consequently, the 45 and sheath 61 extends into the large-diameter bore mirrors and lenses are transparent to visible light. 60. After fiber 18 has been inserted into holder 58, An aiming laser 20 (for example, a conventional it may be fastened by epoxy cement to perma- helium-neon laser) which generates visible light nently affix the components. To complete the as- may be placed in series with IR laser 21 to gen- sembly, the end of fiber 18 which protrudes be- erate a visible light beam. This light beam may be 50 yond surface 62 of holder 58 may be finished flush used to align mirrors 10 and 12 and to adjust with the surface by grinding the assembly or by focussing lens 22 so that the optical fiber system carefully cleaving the fiber. can be aligned prior to performing surgery. Referring to Figure 6, holder 58 (with fiber 18 Also, the optical fibers used to transmit the IR fastened inside) is mounted within a glass tube 51 energy from laser 21 to the surgical area can also 55 to shield the assembly. The front surface, 62, of be used to transmit the visible light from the aiming holder 58 is spaced from the inner surface 142 of laser 20 to the surgical area. Thus, when the inven- planar lens 144, which may be comprised of glass tive apparatus is used in performing surgery where or sapphire, by means of a spacing ring 154. Ring

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154 may illustratively be made of radiopaque ma- Figures 9 and 10 show detailed views of the terial so that the catheter tip can be located inside illustrative four-fiber catheter tip. The four optical the patient by means of a fluoroscope. fibers 42 and the inner shaft 40 which holds the Glass tubing 51 is bent over shoulder 68 of fibers, are held in a fiber holder 50 which is prefer- holder 58 to form a constricted end, 65, which 5 ably formed from a radiopaque material such as holds the probe tip assembly together. A filler, 66, stainless steel or platinum. Fiber holder 50 is cylin- which may be made of a plastic such as TEFLON drical and is provided with a central aperture, 54, (trademark of the DuPont corporation for poly- which communicates with a lumen 34 of approxi- tetrafluoroethylene) fills the annular space between mately the same size that passes through the cen- catheter body 30 and end 65 of glass tube 51 . The io ter of the catheter body 104. Fiber holder 50 is outer diameter of the entire assembly from catheter provided with & plurality of longitudinally extending body 30 to glass tube 51 is substantially the same, holes 56 which extend through the wall of holder providing a smooth, uniform surface along the en- 50 and receive, in a snug fit, the distal ends of the tire length of the catheter as indicated in Figure 6. fiber cores 42. The distal face 58a of the combined Figure 8 shows a schematic diagram of a wire- is fiber cores 42 and holder 50 is polished flat to butt guided, four-fiber catheter for use with the present flush against optically transparent cap 52. invention. The laser system is set up as previously Cap 52 is cylindrical and has the same outer described with the infrared laser 21 constructed in diameter as catheter body 104 so that the two accordance with the above disclosure. A visible pieces define a smooth and continuous diameter. helium-neon aiming laser 20 may also be used in 20 Cap 52 may be formed of a transparent substance line with laser 21 for aiming purposes as discussed such as pyrex glass or sapphire and has an en- with the single fiber catheter. The output of the larged bore 62b extending in from its proximal end. infrared laser 21 is directed towards a set of four Bore 62b terminates at its end to form internal mirrors 60a-68a arranged at a 45° angle with re- shoulder 60. A smaller diameter central aperture, spect to the axis of beam 1 4. 25 64b, is formed in the distal end of cap 52 which The first mirror, 60a, has a 25% reflective aperture may have the same diameter as aperture surface and directs approximately 1/4 of the energy 54 in fiber holder 50 and lumen 34 in catheter body to focusing lens 70. The second mirror of the set, 104 to provide a smooth and continuous lumen 62a, is a 33% reflector which directs 1/4 of the total which opens at the distal tip of the catheter. How- energy to focusing lens 72. Mirror 64a is a 50% 30 ever, the aperture 64b in tip 52 may also be reflector which directs 1/4 of the total laser output somewhat narrower than aperture 54 and lumen 34 to focusing lens 74. The last mirror in the set, as long as sufficient clearance is provided to ac- mirror 68a, is a 100% reflector which directs the commodate a guidewire without adversely interfer- remaining 1/4 of the total energy to focusing lens ing with fluid flow and pressure measurements. 78. Mirrors 60a-68a and lenses 70-78 are conven- 35 Cap 52 is secured by an epoxy adhesive tional devices. (placed on its inner surface 62b) to the fiber holder Focusing lenses 70-78 focus the output energy 50 and also to the portion of the inner shaft 40 and from IR laser 21 onto four fiber optic connectors fibers 42 which are disposed within the proximal ,80-88. Connectors 80-88 are connected, respec- end of the cap 52. The distal end of the catheter tively, to tubes 90-96 which are all connected, via a 40 body 104 is heat shrunk around the inner shaft 40 branch connector 102, to catheter 104. Each of and fibers 42 to provide a smooth transition from tubes 90-96 contains a single optical fiber which cap 52 to catheter body 1 04. transmits 1/4 of the total laser output energy More complete construction details of a four- through the catheter body to the catheter tip 108. fiber catheter suitable for use with the illustrative An additional tube 98 is provided which is con- 45 embodiment are given in US-A-4850351 entitled nected to branch fitting 102 and to a conventional "Wire Guided Laser Catheter", filed on May 22, Luer-Lok connector, 100. This latter tube is con- 1985 by Stephen J. Herman, Laurence A. Roth, nected to a central lumen in catheter body 104 Edward L. Sinofsky and Douglas W. Dickinson, Jr. through which flushing solutions may be injected or Figure 11 illustrates the output beam pattern through which a guide wire may be inserted 50 developed by a four-fiber catheter, such as that through the catheter for purposes of guiding the described above, in which the four fibers are ar- catheter to the surgical area. ranged in two diametrically-opposed pairs. The At catheter tip 108, the four optical fibers which beam pattern from each of the four fiber ends is pass through the catheter are arranged symmetri- defined by a cone formed by the ray lines 70 in cally so that the beams 110 overlap to illuminate a 55 Figure 1 1 . The beam from each individual fiber 42 larger area. Tip 108 also has a hole on the centre is emitted from the distal face of the fiber 42 and thereof, through which guidewire 112 can protrude enters the distal segment 72 of cap 52 through the to direct the catheter to the proper location. face defining the shoulder 60. The beam from each

6 11 EP 0 214 712 B1 12 fiber is divergent and, in the illustrative embodi- the preceding claims, characterised in that the ment, may have a half-angle in the range of 6°- laser energy source (21) operates at a pulse 16°, depending on the numerical aperture of the rate in the range of from 1 to 10 hertz. fibers which are used to construct the catheter. The diverging beam from each of the fibers 42 5 4. A laser catheter apparatus as claimed in any of exits from the distal emission face 74 at the end of the preceding claims, characterised in that the cap 52. Figures 11 A, 1 1 B and 1 1 C illustrate the optical fibre (42) comprises a silica fibre in overall beam pattern (in cross-section) which is which the hydroxyl ion content is reduced suf- formed by the output of the four fibers as seen ficiently to allow transmission of the laser en- along image planes 11 A, 1 1 B and 1 1 C in Figure io ergy. 11. At plane 11 A, which is located at the emission face 74 of cap 52, the four beams in the illustrative 5. A laser catheter apparatus as claimed in any of embodiment are still separate. At plane 11B, the the preceding claims characterised by further diverging beams have spread further and have comprising a focussing lens (22) for directing begun to overlap. At the plane indicated as 11C, is the output of said laser source onto the proxi- the beams have overlapped and define an envelop mal end of said optical fibre, and a lens (144) 73 having an outer diameter which is slightly great- attached to the distal end of the optical fibre er than the outer diameter of the catheter body for directing laser energy propagating down 104. Preferably, at plane 11C, beams 70 will have said fibre to a surgical site. overlapped to merge and cover a continuous pat- 20 tern. Illustratively, such a merger will have occurred 6. A laser catheter apparatus as claimed in any of within a distance from the distal face 74 of tip 52 the preceding claims characterised by further which is approximately equal to the outer diameter comprising additional optical fibres, a plurality of catheter 104 (a typical diameter is 1.5 millime- of partially reflective mirrors (60a, 62a, 64a, ters). 25 68a) arranged in series along the axis of the output from the laser source for directing a Claims portion of said output to the proximal ends of the optical fibres, and a plurality of focussing 1. A laser catheter apparatus for surgically re- lenses (70,72,74,78) positioned between the moving atherosclerotic plaque from a surgical 30 mirrors and the proximal ends of the fibres for site within the body, comprising a flexible cath- focussing portions of said laser output to the eter member (30), a laser energy source (21) proximal ends of the fibres, and means (108) and an optical fibre (42) located within a lumen attached to the distal end of the optical fares defined within the catheter member (30), the for directing laser energy propagating down optical fibre (42) being composed of a sub- 35 said fibres to a surgical site, said directing stantially non-toxic material and being tolerant means holding the fibres in a fixed position to the operation of the laser source, wherein relative to one another so that optical beams the output of the laser source (21) is directed emanating from the distal ends of the fibres into the proximal end (24) of the optical fibre overlap to cover an area at least equal to the (42), propagated along the optical fibre (42), 40 diameter of said catheter. and is directable by means (58) attached to the distal end of the optical fibre to the surgical 7. A laser catheter apparatus as claimed in any of site, the catheter member (30) and optical fibre the preceding claims characterised in that the (42) being sufficiently flexible and being output energy is spread over a 1.5 mm diam- dimensioned to be passed from without the 45 eter surgical site. body, into and along a vein or artery, to the surgical site, characterised in that the laser 8. A laser catheter apparatus as claimed in any of source (21) operates in a pulsed mode with the preceding claims characterised by further pulses of a duration in a range of 0.2-5 mil- comprising an aiming laser (20) source gen- liseconds and a wavelength range of 1.4- 50 erating visible light output and means (10,12) 2.2u.m whereby to provide an effective removal for directing said visible light output through of artherosclerotic plaque. the laser source and the optical fibre to align said laser and said fibre and to visually illu- 2. A laser catheter apparatus as claimed in claim minate the surgical site. 1 characterised by an output of approximately 55 1-2 joules per pulse. 9. A laser catheter apparatus as claimed in any of the preceding claims characterised by further 3. A laser catheter apparatus as claimed in any of comprising a fibre optic connector

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(24,80,82,84,88) affixed to the proximal end of 4. Laser-Kathetervorrichtung nach einem der vor- the or each fibre for holding said fibre. angehenden Anspruche, dadurch gekennzeichnet, da/S die optische Faser (42) eine Quarzfa- 10. A laser catheter apparatus as claimed in any of ser umfa/St, deren Eisenhydroxyl-lonengehalt the preceding claims characterised in that the 5 genugend herabgesetzt ist, urn die Durchlas- catheter member (30) has an additional lumen sigkeit der Laserenergie zu erlauben. passing therethrough, said additional lumen having an opening at the proximal and distal 5. Laser-Kathetervorrichtung nach einem der vor- ends for communicating with said surgical site. angehenden Anspruche, dadurch gekennzeich- io net, da/S sie weiterhin eine fokussierende Linse 11. A laser catheter apparatus as claimed in any of (22) umfa/St, die die Ausgangsenergie der La- the preceding claims characterised in that the serquelle auf das nachste Ende der optischen laser source comprises a Holmium-doped Faser richtet, und eine Linse (144) umfa/St, die Yttrium-Aluminum-Garnet laser, an Erbium- an das entfernte Ende der optischen Faser doped Yttrium-Aluminum-Garnet laser, a is angebracht ist, urn Laserenergie die optische Holmium-doped Yttrium-lithium-Flouride laser, Faser entlang zu der Operationsstelle zu leiten. an Erbium-doped Yttrium-Lithium-Fluoride laser or a Thulium-doped Yttrium-Aluminum-Gar- 6. Laser-Kathetervorrichtung nach einem der vor- net laser. angehenden Anspruche, dadurch gekennzeich- 20 net, da/S sie zusatzliche optische Fasern, eine Patentanspruche Vielzahl teilweise reflektierender Spiegel (60a, 62a, 64a, 68a) umfa/St, die in Reihe entlang der 1. Laser-Kathetervorrichtung zum chirurgischen Achse des Ausgangs von der Laserquelle an- Entfernen einer Atheroskleroseschicht von ei- geordnet sind, urn einen Teil der Ausgangs- ner Operationsstelle innerhalb des Korpers, mit 25 energie zu den nachsten Enden der optischen einem flexiblen Katheterglied (30), einer Lase- Fasern zu leiten, und eine Vielzahl von fokus- renergiequelle (21) und einer optischen Faser sierenden Linsen (70, 72, 74, 78), die zwischen (42), die innerhalb eines in dem Katheterglied den Spiegeln und den nachsten Enden der (30) gebildeten Hohlraums angeordnet ist, wo- Fasern zum Fokussieren von Teilen der Laser- bei die optische Faser (42) aus einem im we- 30 ausgangsenergie zu den nachsten Enden der sentlichen nicht-giftigen Material gebildet ist, Fasern angeordnet sind, sowie Mittel (108) urn- welches gegen den Betrieb der Laserquelle faCt, die an den entfernten Enden der opti- widerstandsfahig ist, wobei sich die Ausgangs- schen Fasern angebracht sind, urn die sich energie der Laserquelle (21) in das nachste entlang der Fasern ausbreitende Laserenergie Ende (24) der optischen Faser (42) ausbreitet 35 auf eine Operationsstelle zu richten, und da/S und durch an dem entfernten Ende der opti- die Richtmittel die Fasern in einer festen Stel- schen Faser angebrachte Mittel (58) auf die lung zueinander halten, so da/S optische (Licht- Operationsstelle richtbar ist, wobei das Kathe- ) Bundel, die von den entfernten Enden der terglied (30) und die optische Faser (42) genu- Fasern ausgehen, sich uberlappen, urn eine gend flexibel sind, urn von au/Serhalb des Kor- 40 Flache zu bedecken, die wenigstens gleich pers in und entlang einer Vene oder Arterie zu dem Durchmesser des Katheters ist. der Operationsstelle gefuhrt zu werden, dadurch gekennzeichnet, da/S die Laserquelle 7. Laser-Kathetervorrichtung nach einem der vor- (21) in gepulstem Betrieb mit Impulsen einer angehenden Anspruche, dadurch gekennzeich- Dauer in einem Bereich von 0,25 Millisekunden 45 net, da/S die Ausgangsenergie uber eine Ope- und einem Wellenlangenbereich von 1,4 bis rationsstelle von 1,5 mm Durchmesser verteilt 2,2 urn arbeitet, wodurch eine wirksame Entfer- ist. nung der Atheroskleroseschicht erfolgt. 8. Laser-Kathetervorrichtung nach einem der vor- 2. Laser-Kathetervorrichtung nach Anspruch 1, 50 angehenden Anspruche, dadurch gekennzeich- gekennzeichnet durch eine Ausgangsenergie net, da/S sie weiterhin eine Ziellaserquelle (20) von ungefahr 1-2 Joule pro Impuls. umfa/St, die sichtbares Ausganglicht erzeugt, und Mittel (10, 20) umfa/St, die das sichtbare 3. Laser-Kathetervorrichtung nach einem der vor- Ausgangslicht durch die Laserquelle und die angehenden Anspruche, dadurch gekennzeich- 55 optischen Fasern leiten, urn den Laser und die net, da/S die Laserenergiequelle (21) mit einer Fasern auszurichten und die Operationsstelle Pulsfrequenz in dem Bereich von 1 bis 10 Hz zu beleuchten. arbeitet.

8 15 EP 0 214 712 B1 16

9. Laser-Kathetervorrichtung nach einem der vor- sion. angehenden Anspruche, dadurch gekennzeichnet, da/S sie ferner einen Faseroptikverbinder 3. Systeme de catheter a laser selon I'une des (24, 80, 82, 83, 88) umfa/3t, der an das nachste revendications precedentes, caracterise en ce Ende der oder jeder Faser angebracht ist, urn 5 que la source d'energie laser (21) fonctionne a die Faser zu halten. un taux d'impulsions de I'ordre de 1 a 10 Hertz. 10. Laser-Kathetervorrichtung nach einem der vor- angehenden Anspruche, dadurch gekennzeich- 4. Systeme de catheter a laser selon I'une des net, da/S das Katheterglied (30) einen zusatzli- io revendications precedentes, caracterise en ce chen Hohlraum aufweist, der durch es hin- que la fibre optique (42) est une fibre en silice durchtritt, und da/S der zusatzliche Hohlraum dont la teneur en ions hydroxyles est suffisam- eine Offnung an dem nachsten Ende und dem ment reduite pour permettre la transmission de entfernten Ende hat, urn mit der Operations- I'energie du laser. stelle in Verbindung zu treten. 15 5. Systeme de catheter a laser selon I'une des 11. Laser-Kathetervorrichtung nach einem der vor- revendications precedentes, caracterise en ce angehenden Anspruche, dadurch gekennzeich- qu'il comporte au surplus une lentille focalisa- net, da/S die Laserquelle einen Holmium-dotier- trice (22) pour diriger remission de la source ten Yttrium-Aluminium-Granatlaser, einen 20 sur I'extremite proximale de la fibre optique, et Erbium-dotierten Yttrium-Granatlaser, einen une lentille (144) montee sur I'extremite distale Holmium-dotierten Yttrium-Lithium-Fluoridlaser, de la fibre optique pour diriger I'energie laser einen Erbium-dotierten Yttrium-Lithium-Fluorid- se propageant dans cette fibre jusqu'au site laser oder einen Thulium-dotierten Yttrium- chirurgical. Aluminium-Granatlaser umfa/St. 25 6. Systeme de catheter a laser selon I'une quel- Revendicatlons conque des revendications precedentes, caracterise en ce qu'il comprend au surplus des 1. Systeme de catheter a laser pour I'elimination fibres optiques additionnelles, plusieurs miroirs chirurgicale d'une plaque atherosclerotique de- 30 (60a, 62a, 64a, 68a) partiellement reflecteurs et puis une zone chirurgicale situee dans le repartis le long de I'axe de remission prove- corps, du type comprenant un catheter souple nant de la source laser pour diriger une portion (30), une source d'energie par laser (21) et une de cette emission vers les extremites proxima- fibre optique (42) logee dans une voie definie les des fibres optiques, et plusieurs lentilles dans le catheter (30), la fibre optique etant 35 focalisatrices (70, 72, 74, 78) disposees entre composee d'une matiere pratiquement non les miroirs et les extremites proximales des toxique et supportant Taction de la source a fibres pour focaliser les fractions de ladite laser, et dans lequel on dirige remission de la emission du laser vers les extremites proxima- source laser (21) dans I'extremite proximale les des fibres, et des moyens (108) montes sur (24) de la fibre optique (42), on la fait se 40 I'extremite distale des fibres optiques pour diri- propager le long de la fibre optique (42) et on ger I'energie du laser se propageant dans ces peut I'orienter par des moyens (58) montes sur fibres vers un site chirurgical, ces moyens I'extremite distale de la fibre optique vers la d'orientation maintenant les fibres dans une zone chirurgicale, le catheter (30) et la fibre position fixe les unes par rapport aux autres de optique (42) etant suffisamment souples et di- 45 telle sorte que les faisceaux optiques prove- mensionnes pour passer depuis I'exterieur du nant des extremites distales des fibres se su- corps, dans et le long d'une veine ou artere perposent de maniere a recouvrir une zone au jusqu'a la zone chirurgicale, caracterise en ce moins egale au diametre du catheter. que la source laser (21) fonctionne selon un mode par impulsions d'une duree de I'ordre de 50 7. Systeme de catheter a laser selon I'un des 0,2 - 5 millisecondes et d'une longueur d'onde revendications precedentes, caracterise en ce de I'ordre de 1,4 - 2,2 urn, de maniere a que I'energie emise est repandue sur une zone assurer une elimination efficace de la plaque chirurgicale de 1,5 mm de diametre. atherosclerotique. 55 8. Systeme de catheter a laser selon I'une des 2. Systeme de catheter a laser selon la revendi- revendications precedentes, caracterise en ce cation 1, caracterise en ce que son emission qu'il comporte au surplus un laser de pointage est d'approximativement 1-2 joules par impul- (20) emettant une energie en lumiere visible et

9 17 EP 0 214 712 B1 18

des moyens (10, 12) pour diriger cette lumiere visible a travers la sourcelaser et la fibre optique en vue d'aligner ledit laser et ladite fibre et eclairer visuellement la zone chirurgicale. 5 9. Systeme de catheter a laser selon I'une des revendications precedentes, caracterise en ce qu'il comporte au surplus un connecteur de fibres optiques (24, 80, 82, 84, 88) monte sur I'extremite proximale de la (ou chaque) fibre 10 en vue de la maintenir.

10. Systeme de catheter a laser selon I'une des revendications precedentes, caracterise en ce qu une voie additionnelle traverse le catheter is (30), cette voie s'ouvrant aux extremites proximale et distale en vue de communiquer avec la zone chirurgicale.

11. Systeme de catheter a laser selon I'une des 20 revendications precedentes, caracterise en ce que la source laser est un laser au grenat d'yttrium et d'aluminium dope a I'holmium, un laser au grenat d'yttrium et d'aluminium dope a Terbium, un laser au fluorure d'yttrium et de 25 lithium dope a I'holmium, un laser au fluorure d'yttrium et de lithium dope a Terbium ou un laser au grenat d'yttrium et d'aluminium dope au thulium.

10 EP 0 214 712 B1

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65 ,63 r/$ s5l r62 r55 /^-|

r/44 FIG. 6 ■66 58 14^^154 ^-142.

FIG. 7

r 62 65 ^ 60^

■67

40 r42

64b

FIG. 9

FIG. 10

■42

14 EP 0 214 712 B1

15 EP 0 214 712 B1