CA2001336C

CA2001336C - Delivering laser energy

Info

Publication number: CA2001336C
Application number: CA002001336A
Authority: CA
Inventors: Kenton W. Gregory; R. Rox Anderson
Original assignee: General Hospital Corp
Current assignee: General Hospital Corp
Priority date: 1988-10-24
Filing date: 1989-10-24
Publication date: 2001-05-08
Anticipated expiration: 2009-10-24
Also published as: US6066130A; JP3222885B2; EP0445182A1; US5649923A; ATE176141T1; EP0445182B1; DE68928921T2; WO1990004363A1; CA2001336A1; DE68928921D1; EP0445182A4; JPH04501226A

Abstract

A method for conducting laser energy to a site includes steps of bringing the proximal end of a flexible tuba near the site. filling at least a proximal portion of the tube with a liquid by introducing the liquid into the tube, allowing a portion of the liquid to flow out from the proximal end of the tube toward the site, and directing laser energy from a laser energy source into the distal end of the tube. whereby a portion of the laser energy emerges from the proximal end of the tube at the site. Also, such a method in which the liquid is a radiographic contrast medium.
Also, such a method for removing an obstruction from a blood vessel in an animal. Also, apparatus for delivering laser energy to a site includes a flexible tube, a liquid, the tube having an opening in a first end through which the liquid can pass, means for providing a flow of the liquid into the tube, and a source of lager energy operationally associated with a second end of the tube, wherein the tube and the liquid are adapted to cooperate, when the tube contains the liquid, to conduct laser energy from the source and to emit a portion of the laser energy from the first end of the liquid-containing tube.

Description

i a . ~, _, ~ ~ o ~ : ~ ~ ~ ~,.z ~ F x s H ~. ~ x c H w xx to s o rr 2~~136 ..~_ DELIVERINf3 LASER ENERGY
Background of the Invention This invention relates to conducting lager energy from a laser energy source along a course that includes curves of small radius.
In many circumstances in various industrial and medical applications, matter to be cut or welded or otherwise altered or removed i$ located at a Bite that is inaccessible or difficult to reach.
o Many sites within the body of an animal such as a human patient are difficult to reach for performing surgery, because they are surrounded by hard tissues such as bane or because they are surrounded by delicate tissues which can be damaged. Sites within the thorax, such as the heart and the blood vessels near it, for example, are enclosed by hone structures. and sites within the cranium, such as arteries supplying the brain, for exempla, are surrounded by delicate brain tissue as well as by bone, The coronary arteries and the arteries of the brain can become occluded for example by atheromatous plaque formations or by thrombi or emboli, with serious consequences for the patient, One approach to providing a supply of blood to the heart when a coronary artery is occluded is bypass surgery, that is, coronary artery bypa$$. The patient's thorax is opened, and a substitute conduit for supplying blood to the heart is provided by engrafting a substitute vessel between a point up$tream from the occlusion, such as the sarta, and a point in the 3o coronary artery downstream from the occlusion. Coronary bypass surgery is an involved and delicate procedure, entailing significant risk and expense to the patient.
Many patients are unable to benefit fxom bypass surgery, In an alternative approach to relieving an' 1 L~1 . r : ? . '~ ~ U 4 : :~ ~ P 2~Z ~ F I S H a. R I C H A R D S O N P.y o 2~U~.336 occlusion of an artery, dxuga are administered to pause the vessels to dilate, Not all patients can use such drugs, however, and the results are generally anly temporary, as the occluding process can continue, eventually blocking even the dilated vessel, In still other approaches, generally termed percutaneous translumenal engioplasty, an instrument for di7.ati,ng the occluded arterlr is introduced, generally by means of a catheter, through an opening in the skin and to through an opening in the wall of a large artery such as the brachial artery ox the femoral artery, and passed within the arterial. lumens to the site of the occlusion. In balloon angioplasty, for example, a fine guide wire is first passed to the site o~ the occlusion ~5 through the lumens of major arteries, observed by radiography as it progresses; then a catheter having a balloon near its tip is passed over the wire to the site, also within the arterial lumens; and ~inally the balloon ie inflated at the site of the occlusion to 20 stretch the walls of the artery and open the lumen. The results of balloon angioplasty can also be temporary, as the occluding process in 30-40% of patients can continue at the sits until the vessel is again blanked.
Moreover, the procedure carries risks of perfara~tion or 25 acute occlusion of the arteries by the Instrument, and the flow of blood through the vessel being treated is interrupted for a time during the arocedure. Only aelocted patients can benefit from balloon angiaplasty, leaving many patients with no viable treatment, 3o including patients having atheroma$ involving long segments of vessels, or having diffuse distal artery disease, or haring arteries too tortuous to permit passage of gu3dewires, In a variety of industrial and medical ' 1 c~~. ~: a._ 8 ~ G 4 : .a ~ p z,.t ~~ F Z S H 2" R t C H A R a S O N Fe._r~7 ~
2~~x.336 applioations, useful results can be obtained by directing laser energy at a site. Far example, various materials melt or vaporize upon absorption of laser energy. and parts constructed of such materials can in effect be cut or welded to achieve a desired result.
Laser energy ce~n be used in surgery for alteration ar removal of tissues or obstructions or deposits by diz~ecting the energy at the matter to be altered or removed.
ZO Zr~ a surgical technique known as laser angioplasty, conventional light guides using fiber optics have been employed for directing laser energy onto arterial plaque formations to ablate the plaque and remove the ooclugion. Individual optically conducting fibers are typically made of fused silica or quartz, and are generally fairly inflexible unless they are very thin, A thin fiber fl$xible ~nough to pass through a course having curves of small radius, such as through arterial lumens from the femoral or the brachial artery 2o to a coronary artery, typically projects a beam of laser energy of very small effective diameter, aapaDle of producing only a very small opening in the occlusion;
moreover the energy i$ attenuated over relatively small distances as 3t passes within a thin fiber. Small z5 diameter fibers can tend to mechanically perforate vessels when directed against the vessel wall as they are. passed within than vessel toward the site.
In order to bring a sufficient quantity of energy from the laser to the plaque, light guides 30 proposed for ue~ in laser angioplasty usually include a number of very thin fibers, each typically about 100 to X00 microns in diameter, bundled together or bound in a tubular matrix about a central Lumen, forming a catheter, Laser energy emerging from a small number of 1L~. ":~, o=~ t_i4,: ~~ F2..z ~FiSI-I ~ RI CHARD SON yelp ;~ooa~~3s fibers bundled together in known such catheters produces lumens of suboptimal diameter which can require Subsequent enlargement by, for exampl~, balloon dilation. such devices do not remove an adequate quantity of matter from the lesion, and their uses are generally limited to providing access for subsequent conventional balloon angioplasty.
Moreover, although individual fibers of such small dimensions are flexible enough to negotiate curves io of fairly small radius, a bundle of even a few such fibers is much less flexible, and use of laser angioplasty has as a practical matter been limited to the larger, straighter blood vessels such as. for example, the large arteries of the leg, in which the laser energy is conducted by the light guide over only relative~.y short distances on a relatively straight course. Coupling mechan~,sms for directing laser energy from the source into the individual fibers in a light guide made up of multiple small fibers can be complex.
p including lenses xr~d mechanisms by which the individual fibers can be addressed serially by the source beam.
zmproper launoh of the laser energy into such a light guide can destroy the fibers, ruining the instrument and endangering the patient.
Mare flexible light guides can be provided by filling a flexible tube with a liquid material whose refractive index is less than that of the tube wall material. H.F. Eastgate, U.B. 8atent No, ~,0~5.119, describes a liquid core light guide, having a plug at 3o each end of the tube to seal the liquid in, for transmitting laser energy at high power from a laser source such as a pulsed laser to an area of application, The presence of blood near the distal end of such instruments can prevent laser light from reaching 1 O . ~, :a ,o ~ 0 4 : :~ ~ F' ri ~ F I S H ~ R I C H A R D S O N F'._.1 1 ~~1336 -s-.
its appropriate target, such as for example arterial plaque or a blood clot. Moreover, absorption of laser energy by blood or blood components can result in generation of heat o= formation of detonations, which s can damage adjacent veg$el walls, Summary of t, he Invention We have discovered that laser energy can be efficiently conducted along a course that includes curves of small radius and directed onto a target at a 1Q remote Bite by launching laser energy into a liquid-filled flexible tube that is at least partially open at the end nearest the site so as~to permit a portion of th~ licxuid to flow out from that end toward the target.
15 In general. in one aspect, the invention features a m~thod for canductinq lasex energy to a site, including the steps of bringing the proximal end of a flexible tube neax the site, filling the tube with a liquid that can include a radiographic contrast medium, 20 and directing laser energy from a laser energy source into the distal end of the tube, whereby a portion of the lasex energy emerges from the proximal, end of the tube at the site. In some embodiments the tube ig provided with means for limiting the flaw liquid out 25 from the tubs at the proximal end.
In another aspect, the invention faratures a method for conducting laser energy to a site, such as into a site of the body of an animal, including the steps of bringing the proximal end of a flexible tube 3o near the $ite, providing a flow of a liquid into the tube, and direoting 3aser energy from a laser energy source into the distal end of the tube, whereby a portion of the laser energy emerges from the proximal end of the tube at the site. ' 1 U ., ~: :~_ 8 ~ G 4 : :3 ~ P Ls ~ F I S H ~.: R I C H A R D S O N P _..1 2 ~U1336 In preferred embodiments, a portion of the liquid is permitted to flow out from the proximal end of the tube toward the site; the step of bringing the proximal end of the tube near the site includes passing s it into the body of the animal by way of an opening in the animal, or by direct surgical approach, and includes passing it through the lumen of a passage within the body of the animal, such asc through the Iumen of a blood vessel of the animal. The site includes a mineral 14 deposit, an atheromatous plaque, an atheroembolus, a thrombus, or a, blood clot; the site is located in a body space such as in an artery, in a vein, in a ureter, in a common bile duct, in the trachea, in a bronchus, or in the gaatroint~stinal tract. The step of providing a 15 flow of a liquid into the tube includes passing the liquid from a source of into the tube by way of a part in the tube wall; the method further includes the step of continuing to pas$ the liquid into the tube after the tube has been filled with the liquid, whereby a portion z0 of the liquid passes out from the proximal end of the tube.
Causing the liquid to flaw from a source of liguid in a controlled manner through the tube and proximally out fxom the tube during the treatment can 2s produce a column of liquid between the proximal end of the tube and the target, effectively permitting a continuous guide for the laser energy for a short distance beyond the proximal arid of the tube. A variety of body fluids, such as, for example, blood or urine.
30 have indices of refraction sufficiently low with reap~ct to the liquid in the tube to provide such a light guide effect beyond the proximal end of the tube, Moreover, matter that may inter~eze with the laser treatment, ~,noiuding sub$tances noxmally present at the site,~suCh 1 0~ ... _ o ~ t~ 4 : ~ ~ Pr~.z *. F t SH ~-.. R t CHARZySON P.1 3 _7_ as blood i,n the case where the site is within a blood vessel, or substances prodLCed at the site as debris during the treatment, can be continually flush~d awa7 without interrupting the procedure by the flow of liquid out from the proximal end of the tube, In another aspect, the invention features a method for removing an obstruo;tion from a blood vessel ,in ari animal, comprising bringing the proximal end of a flexible tube near th~ obstruction, filling the tubo 1o with a Iiguid by passing the lic,~uid into the tube, continuing to pass the liquid into the tube after the tube ha~ been filled with liquid, so that s portion of the liquid pas$es out from the tube at the proximal end, and directing laser energy from a source into the distal end of the tube, whereby a portion of the Iasor energy emerges from the proximal end of the tube and strikes the obstruction, Where the obstruction includes era atheromatous plaque. the method can be one for treating atherosclerosis; where the obstruction includes a 2o thrombus, the method can be one for treating thrombosi$
or thromboembolism.
The method does not require completely restricting the flow of blood through the vessel being treated, so the procedure can be carried out without haste, Moreover, the flushing action of the liquid flowing out from the tube towx~rd the target can enhance laser~energy delivery by removing blood, which can absorb wavele~gthe of laser energy that can be useful for removal of plegue or thrombus, 3o In another aspect, the invention features apparatus for delivering laser energy to a situ.
including a liquid, a flexible tube having an opening in one end, arranged and adapted to be brought near the site, through which the liouid can pass, means fore 1 ra. "-a._ ~ ~ ~~ 4 : :3 ~ pT~.z ~. F I SIi ~ R I GHARD SON y_Z 4 ~~~~.336 providing a flog ;.: t.:ze liquid into tha tub~, and a source of laser e: ~rg'~r operationally associated with another end of the t;~:oe, wherein the tube and the liC:id contained wi,thir. . can cooperate to conduct laser energy from th~ s~:roe and to emit a portion of the laser energy from tb,o second ersd of the tube, In preferred ernbodtments, at least a portion of the tube is adapted to be bent without substantial ahenge in oross~sectfanal shags or without kinking ipso a curve having a radiig of curvature as small ae 20 cue, more preferably as sxail as 1o rrm; The tube includes a wall having a refractive index nw, one surface of the walwl describing t:a Renal surfac~ of the tube, and .he liquid has a refracti~~e index n f, wherein n f is 1~ greater than nw; ~;e values of of and nw are such that the ratio ~ f,~w " (nf)/tnw) is greater than 1, 7 , more preferably greater than abc_t 1.05, still more r e:erably greater than about 1.1; to value of of is abc~a 1.46, or at least about y.46; tre value of nw is abva 1.33 or at least about 1,33. tke liquid includes a :adiographic contrast medium; the liquid is bioco~pa:ible; a support layer surrounds the z5 wall; the wall is z~ade of a polymer, preferably a f luor inated polyaae: , Such as tetref luoroethylene hexaf3uoropro8ylena (FEp) or polypentadecafluorooctyl-acrylate elastocaer, A cap is affixed to the first sad of the tube; tha cap is arranged and adapted to 3o substa,nt sally rest= is t movement of the 1 ic~uid out fray the tube by way ef the f ~, r st end; the a ap i s conf i gored to provide a smcoti cad rounded proximal surfaa~;~ the caP ha$ a bore thr~ug:~ it substantially aligned with ~.he axis of the tube, ~re_erably of a diameter suffiaierit:y 1 ~. ~,=.. ~i~ 04 : ;~~ Pt"z .nFISH ys: RI CHARD SON y.....1 ~01336 to perm: passage of a guidewire through it. preferably sufficiently small to restrict the flow of the liquid through ;t, preferably about 500 micrometers, or at 7,east abcut 500 micrometers: the cap is made of duartz, ar of sarphire; the cap has a reflective surface arranged and adapted to direct the laser energy in a direction away from the axis of the tube: The lumen o!
the tube has a transverse dimension, between a.Dout 1 asa and 3 mta: the Iumea has a substantial3y circular cross-sectional shag~; it has a diameter between about 1 mrn and 3 :pan. The apparatus further includes a coupler at a the second end of the tube for conducting energy from the source of laser energy to the liquid-containing tube: the coupler comprises a window, a lens, or an optical fiber (pre:era,bly iz3serted into the lumen of the tie): rte coupler is made of quartz or fused silica:
th~ means for providing a flow of the liquid into the tube inc_udes a conduit for conducting the liquid between :~he source and the tube; the tube includes a 2o port intermediate its first and second ends for passing the Iiqu~d between the source and the tube; the means for providing a flow of the liquid into the tube further includes a filter to prevent bubbles from moving into the tube.
Ia other einbadimet~ts, the tub~ wall includes a reflective layer, one surface of which describes th~
lumenal surfaQe of the wall: preferably the xefleativo layer is of a reflective polymer or metallized material.
such as a mat$ri81 including aluminum or silver, 3o coextruded with or bonded to the lumenal surface of the tubing material.
I'2~e liquid-core light guide according to the invention can be made Sufficiently flexible to negotiate the small curves commonly encountered in finer arteries 1 C7 . ~ _~.. ~ ~1 O 4. : ;~ ~ F z,.i *: F I S H .3: R I C H A R D S O N F-_..1 g ~~1336 - Io -such as the coronary arteries, while pro~ectinq an effective beam sufficiently broad to remove an occlusion, The tubing for the light gaide itself can be simply and irsexpen$ively made by, for example, a con~inuous extrusion or coextrusion process, and cut for length ae rehired fvr each particular use. Advancing the light guide through arterial or venous lumens can be facilitated by initially advancing a guidewire along the course to be followed and then advancing the light guide In ove: the guidewire to the target location.
Alternatively, a guiding catheter can be ~mplaced at the ori3in of the obstructed artery and the light guide can be advanced within the lumen of the guiding catheter, The laser energy Source can be coupled to the light 15 gui3e in a straightforward fashion, presenting few launch complications. The laser energy can be launched directly from the Iaser through a focusing Iens to the iic~at guide or alternatively it can be launched initially into a corwentioral (fiber inserted into the .o lumen of the light guide at the distal errd.
fhe liquid and the tube can be made from biocompatible materials, Csinq a radiographic contrast rredwum as a liquid permits continuous fluoroscopic imaging of progreBe throughout th8 procedure without 25 interruption,, Moreover, a light guide containing a radiographic contrast medium can be used with fluoroscopic monitoring to deliver laser energy with precision in nosunediaal applications where the site to bQ treated ie accessible only by way of a tortuous 3o pathway, Such as, for example, in repair or rea~nstruction of internal parts of hydraulic apparatus in which the hydraulic fluid is a hazardous mat~rial, 1 U . ~, :s , c3 ~ C~ 4 : :~ ~ P T,.i *~ F I S H ~ R I C H A R D S O N F._.1 ~r 2~~J13~6 _m_ ~escri, tion of the preferred Embodiments ~rawinas ig ~ 1 is a socu~ewrat diagrammatic view of porno..~.s o:' a liquid core light guide according to the invention, partially cut away along the long axis of the t ube , Fiq~ a is a eectio~ thru the light guide of ~'ig. 1. at 1"ig~ 3 is a somewhat diagrammatic view of the 1o distal portion of a liquid core light guide, cut away along :he long axis of the tube, showing a liquid port and aozd;:it for passing lia~id into the tube, Figs, ~ through 7 and 9 are somewhat diagra~ratic views of the proximal portion of a liquid core light guide, cut away along the long axis of the 'rye. showing end caps in various configurations.
gi9~ 8 is a section thru th~ proximal portion of a lic~:id core light guide of Fig. 7 at 8-8.
~'ig . 10 is a somewhat diagrammatic view of 2o port ions of an alternate 1 squid core light guide of the :nventicn, partially cut away along the long axis o~ the ;, ube , f'ig. 11 is a section thru the light guide of Fig, 7 at 8-8.
Fig. 12 partially cut away through the long as~is of the tube, showing a window for couglinq a source of laser eo;ergy to the light guide.
Fig. 13 partially out away through the long ~i$ of the tube, showing any alternate laser coupler 3o employing an optical fiber.
Fig, 14 is a somewhat diagrammatic view of the proximal portion of an alternative liquid core light Guide of the invention, cut away along the long axis of 'che tube. having a xeflectiYe lumenal surface.

1 0 . .r _~. c3 9 O .~ : ~ ~ p hi ~ F I S H as. R I C Ii A R D S O N Fe.. .
:00136 - l~ -~'ig. 15 is a somewhat diagrammatic view of the proximal portion of a liquid core light guide of the invention, cut away along the long axis of the tube, in combination with a balloon dilation device.
Fig. 16 is a somewhat diagrammatic view of the proximal portioa of a liquid core light guide of the invention, cut away along the long axis of the tube, showing a light diffusion balloon.
Structure and Operation i0 Figs, 1 and 2 are views of a liquid core light guide of the invention. The light guide includes a tube, Shown ganeraliy at 10, whose wall z6 encloses a lumen 2~ which is filled with a liquid x6, The inner surface of wall 16 defines lumenal Surf sae 22 of tube 10, 1$ Laser energy can be directed from a soure~ of laser energy (not sho,~ in Figs. 1 and a) into distal end 1~ of liquid filled tube 10, as indicated generally by arrow I. The energy passes within the lic,~uid tilled tube toward proximal end 12, The energy is attenuated zo as it Passes away from the sourc~, so that a portion of it emerges from proximal end 12, as indicated generally by arrow 0, The proportion of the energy introduced to the distal end that emerges from the proximal end of the liquid-filled light guide depends upon tho dimensions 25 and physical characteristics of the liquid and the tube wall and on the extent to which the tube follows a curving aoure~.
deferring now to Fig, 3, port 62 through wall 16 is provided near distal tube end 14, and one ~nd of 30 conduit 6~ is coupled to point b2, Fluid can b~
introduced at the other end of conduit 64 as indicated by arrow F from a source of 1 iquid such as a syr inge or a pump, such as, fox example, a peristaltic pump (not shown in Fig. 3), into tube 10 through conduit b4 via 1 C~ . ~ :.. o ~ U 4 : ~ ~ F° ztd ~ F I S H ~ R I C I-I A R D S O N
F~_..1 ~:0~1336 w ~~ w port s2. Similarly a conventional guide wire (not shown in~Fig, 3) can be introduced into tube 10 through conduit 1~ via port 6a.
The materials for wall 16 and for liquid 26 arc selected in part to provide a high degree of internal reflection at the iumeaal surf ace: that is, wall 16 and li~~a Z~ are each transparent to the laser energy to be conducted through the light guide, and the index of refraction nw of wall 16 is greater than the index of refraction rif of liquid 26.
~rther, the material for wall 16 i$ selected in part to provide structural strength as well as flexibility so that the liquid-filled light guide can be bent through curves of small radius without kinking or substantially distorting the arose-sectional geometry of the ti:be , k~referably wall 16 is made of a f luorinated ethylenepropylene, such as i$ available commercially for examp:e as "FEP ~eflon4", and the liquid is a z0 radiographic contrast medium, such as is available commercially for example as "Renographin 76e". FEp Teflote has a refractive index about 1,33, and Renographin 76m has a refractive index about 1,~6; the ratio of their refractive indices i$ thus about 1.1, providing for substantially total internal reflection even at fairly steep angles of incidence. Preferably th~r lumenal surface of the tube smooth, as irregularities in the surface can introduce unsatisfactory irregularities in angles of incidence.
3o Preferably the tube has a circular cross-sectional shape, and th,a iruier diameter ( i . e, the diameter of the lumen of the tube) is about 1-3 mm according to the diameter of the arterial lumen to be opened. T?referably the thickness of the wall 16 is at least about two Limes 1 rJ , ~. :a...4 8 ~ 0 4 : -:3 ~ F~ z,.s " :* F I S H ", R I C H A R D S O N
~~1336 ,w 1 ~ w the wavelength og the transmitted light. Such a tube, 110 crn long, with, a wall o~ FrP Teflan~ and containing Renographin 76m, can transmit from the proximal end about 6Q9~ of laser energy st X80 nm, launched through a refractive index--matched lens or window into the distal end from a laser, Alternatively, the laser energy can be launched into a conventional quartz fiber from the laser, and the quartz fiber can be inserted into the distal end of the :0 tube. However, distal portions of the tube which contain such a fiber are thereby rendered much less flexible, and it i~a advantageous in applications where great flexibility is required particularly in a proximal portion of the light guide not to insert the ffiber so far that the proximal end of the fiber reaches into the preferably flexible proximal region of the light guide.
Such a tube of such composition can have a "memory"; that is, the tube can be preformed to conform to a particular desired curvature, so that, while it can ?0 be straightened of flexed, it will tend to conform to a particular anatomical course corresponding to the preform curvature, Some materials that are optically suitable far use as a tube wall axe structurally unsuitable or less suitable; that i$, they are insufficiently flexible, or they collapse or kink ar otherwise are distorted when they are bent through curves of small radius, Fige. 10 and 11 show arr alternate construction for the tube, in which the tube 16 includes inner wall layer 18. whose 3o inner surface de~ine~ the lumenal surEac~ as of the tube wall 16, and outer supportive layer 20, Inner wall layer ~.8, situated adjacent the lumen 24 of tube 10, is constructed of material having suitable optical characteristics, as described above with reference to lCa. ~__,. g:~ ~4: 3~ PP,.rl mFISH '~ RICHARD~ON F'....y1 - is Figs. 1 and Z. Outar wall layer 20, which can be bonded to in.~er wall Iayex 18 or coextruded with it, is formed of mater~.al having suitable mechanical properties, so that tube wall 16 has structural strength as well as f~,exibxlity, as described above generally with r~ference to Fig~. 1 and z, The laser light guide operates generally as follows, with specific reference to its use for ablating arterial plaque occluding a coronary artery, Tube 10 ie filled with filled with liquid 26, and a source of laser energy is coupled to th$ distal end Z4 of the liquid-filled tube, Fluid-filled tube 17 is introduced proxiTal end first through an opening in the skin and through the wall of a large artery such as the femoral artery, and is then passed translumenally toward the site of the occlusion to be treated by laser energy, until the proximal and resides in the lumen of the occluded artery and is directed toward the occlusion.
If the liquid is a radiographic contrast medium such as zo Renographin 760, the progess of the tube toward the site can be followed by x-ray without interruption either with or without use of a guide wire. Once the proximal tip has reached the site and is directed toward the target, a further quantity of liquid can be introduced into the tube fraar a liduid source, causing some liquid to emerge from the proximal end of the tube toward the target. Blood situated between the tube and the target can interfere with laser ablation of the plaque, because the blood absorbs nearly all wavelangthe of laser energy better than does plague. The liquid passing from the proximal and of the tube displaces blood between the tube and the target removing this interference. As the emerging liquid displaoes the blood, it provides a liquid channel proximal to th~a 1 ~~ . _. _ t3 ~ « .~ : 3 ~1 Y TvS %K F I ~ H ~.. R I C H A R D S O N ~ ..r ....._.. . . ..
~:~J~.336 proximal ~nd of the tube for passage of laser energy to the target. Moreover, the index of refraction of blood is about 1.34, sufficiently low relative to that of the lic,~uid that the blood surrounding the liquid in this channel forms an eff Active light guide between the proximal end of the tube and the target. Such a temporary liquid-core, liquid-clad light channel can be effective over distances in the order of about a certtirneter for time intervals generally sufficient in the usual circumstance to complete the ablation and open the arterial lumen, Then the laser energy source is activated to produce Iaser energy having the desired wavelength and pulse duration and intervals. The progess of the laser ablation of the target can b~ observed by x-ray, as the liquid serves not only as a light guide component but also as a radiologic contrast medium. When the ablation has been completed, the liquid-filled tube i$ withdrawn.
A guide wire can be used in the above-described zo procedure as desired. for example, i~ the walls of the arteries to be traversed by the tube themselves contain plac,~ue formations that would interfere with the passage of the proximal end of the tube during insertion. The guide wire traverses the liquid-filled lumen of thv tube. A preformed tube as described above follows the course of the guide wire during insertion; once the tube i$ emplaced the guide wire aan be removed, and the tube then conform tv its curving course through the arteries.
Alternatively, as Shown in Figs. 4 through 9.
3o the proximal end of the tube can be provided with an end cap, to inhibit flow of liquid out from the proximal end, With reference to Fig. 4, er~d cap 40 has generally cylindrical portion 4~ whose diameter is such that portion 4! can be press fitted into tube 10; and an end 1C~. ":.~.. 8~ L74: ~~ FT..2 fi:FISH ~ RIGHARDSON
~~1336 ~. i ~ -portion 45 farming a shelf 46 that abuts proximal tube end i2, A hole 52 runs through the center o~ end cap 40, situated so that it is aligned with the long axis of tube 10 when end cap 40 is in place, Hole 52 has a diameter sufficiently large to permit pa$sage of a guide wixe. Where desired hole 52 can be made with a diameter sufficiently small that the flow of the liquid out from the proximal end of the tube is restricted under conditions of us~, For standard guide wires, and for to aqueous liquids, a d~,ameter about 500 microns can be suitable, end portion 45 is shaped to provide a smooth and rounded proximal surface, so that the light guide aa~n be easily passed proximally to the site without becoming caught or damaging the vessel wall.
~5 Figs, 5 and 6 ~how alternative end asps 50 and 60, adapted to be more securely fastened to the proximal end~of tube 10. Generally cylindrical protion 54 of end cap 50 includes annular ridge 58, and tube 10 is provided near end Z2 with annular groove 59 into which 2o annular ridge 58 fits when end cap 50 is seat~d with sheig 55 of end portion s5 in abutment with tube and 12. Generally, cylindrical portion 54 of and cap GO
includes annular groove b8. End sap 60 is press fitted into tube i4 so that shelf 66 of end portion 66 abuts 25 tube end 12, and then retaining ring 70 is placed about tube 10. cornpressinq an annular portion of wall 16 into groove 68. End caps 50 and 60 are provided with holes sZ and 6Z corresponding to hole 42 in end cap 40 as described above with refer~nce to Fig, 4"
3o Fig$, ~ and 8 show an alternate embodiment of a liquid core light guide of the invention, in which a passage for the guide wire is provided separate from the lumen containing the laser energy aonduoting liquid.
Tube wall 16 is provided with a lumen 24 bounded by' 1 Co. .: :,~, ~ ~ ~ ~ 4 : i ~ P z.,T ~ F I ~ H ts, Fe I G H A Ft D S O N ~._~, ~~001336 lumenal surface 2Z similar to that described above with reference to Figs. I through 3, 10 and 11, in which the liquid is located, A thickened portion 90 of wall 16 is provided with a longitudinal bore 92 through which a guide wire can pass, End cap 80 having a generally cylindrical portion 84 is press fitted or heat welded into the proximal end 88 of the tube. Qenerally cylindrical portion 84 of cap 80 is provided with an annular swelling 86, which conforms to the inner surface of the tube wall to form a secure attachment when the cap is assembled into the tube, End cap 80 can be provided with generally axially situated bolo 82, if it is desired to permit a flow of liquid out from the proximal sad of the tube, Alternatively, if no hole is i5 provided in end cap 80, then end cap 80 provides a $eal for preventing a flaw of the liquid out from the tube, as may be desired for example if the liquid is corro8ive to the surroundings near the site to be treated by the laser energy; or if the liquid is toxic or otherwise not biocompatibie, as may be a concern in a medical application, Many liquids that are suitable for W or for zR laser transmission, as generated for example by excimer, Holmium, or Erbium YAp lasers, are toxic or nonbiocompatible, while many radiographic contrast media transmit W or far IR wavelengths only poorly.
8'ig~ 9 shows an alternative construction for tha cap, whereby the cap provides a reflective surface to,direct the laser energy out through the tube wall in a dir~gction away from the axis of the tube, End cap 1~0 3o is affixed g~nerally as described above into the proximal end of the tube. The distal end of generally cylindrical portion 124 of cap 1Z0 is provided with a reflective surface 126, which is shaped and oriented so that it reflects the laser energy in a desixed 1 C~.. ,r :~., o ~ O 4 : 3 ~ P x,~i ~ f I S H '~ R I C H A R D S O N P..., :
~, direction, such as for example a direction generally perpendiCUlar to the tube axis, as shown at arrows R in Fig. 9. A aide hole lz8 can be provided in wall 16 in the area where the light reflected from reflective surface 1Z6 as at arrows R passes through the wall, to allow fluid to pas$ out from the tube toward a site situated lateral to the tube. this flow of fluid dieplacos blood in the sons between the tube wall and the target site, providing a temporary liquid-COra, l0 liquid-clad light guide as described above for conducting the laser energy to the target, Alternatively, a window can be affixed within hole 1.28 of wall 1B, made of, for example, quarts or sapphire, which is transparent to the reflected light i5 but does not allow passage of the liquid, Such a window can prevent leakage of the liquid into the site, and can be d~sirable where, for example, the liquid is itself toxic or otherwise nonbiooompatible; or, in industrial applications, where the liquid is incompatible with the 2o material$ at the site, As desired, the reflective surface 126 can be planar, or can be curved such that it causes the reflected laser energy to diverge or converge.
The end cap can be formed far example of quarts 25 or of fused silica by for example end-melting a length of quartz ox fused silica capillary tube having appropriate dimensions. The cap material can be optically matched with the liquid, such that, for exxunple, the liquid and the cap have nearly the same 30 index of refraction, and the interface between the liquid and the Cap i$ not seen by the passing laser energy. If a cap is provided with a reflective surface, for example as described above with reference to Fig. 9, then the cap Can have an index of refraction ' lci,. ~.'-i.. 89 04: ~.r-~ p2..z :*FISH '~. RI CHARD SON
~01336 - zo -sufficiently different from that of the liquid to provide reflection at the interface, or the reflective surface can be provided with a reflective film or coating.
The light guide can be coupled to the source of laser energy by means known in the art of laser light ~iQ~'s, ~'ig~ l2 shows a window 98 a~~fixed to the distal end 14 of the tube, The laser energy i~t directed as shown generally by arrow x in a direction generally 1o caaxial with the tube lumen 24 from a laser energy source, a portion of which is indicated diagrammatically at L, toward window 98, through which it passes into the tube lumen 24. Such a window carp be made for example of quartz ar fused silica having an index of refraction FS matched with that of the liquid, $o that the interface between the liguid and the window is not seen by the passing laser energy.
An alternative coupl~r is shown in Fig, 13.
This coupler can be used to launch the laser energy into 20 the light guide from a conventional optical fiber that is Conventionally coupled to the source of laser energy, and the coupler provides a Y connector shown generally at 100 through which the liquid can be introduced while the light guide is in use, Y connector 100 includes a 25 generally cylindrical barrel 102 having an end 103 configured to fit over the distal end 14 of the tube, A
seal is establi$hod between barrel ioz and tube end i4 by heat-shrinking a length of tubing material 105 over the joint. Conduit 104 projects from barrel 10a, to 3o provide for introduction of liguid from a source of liquid, indicated diagrarnatically at S, into couplor 10o and lumen 24 of the tuba, A conventional bubble filter, indicated generally at B, is interposed across the flow of liquid, indicated generally at F, for preventing 1 Q. .r :_~.. ~ 9 0 .~ : ~ ~ p Tai :~ F r ~ H x, R I G H A R D S O N F..~:'-:
?
~~0133 introduction of gas bubbles into the lumen 24 of the tie, Distal end IQ8 of coupler 100 is affixed with a cap 106; which is provided with bore 107 through which conventional optical fiber 114 can pass, Distal cap 106 s is provided with annular groove 110, which accommodates 4-ring 11a to provide a seal between distal cap 106 and fiber 114. Fiber 114, which can be provided with a conventional ball tip 116, is advanced proximally into lumen ~4 of th~r tube as far ag is desired. Because 14 fiber 114 is insufficiently flexible to pass through a course haying curves of small radius, fiber 114 should not be advanced proximally beyond portions of the tube where such bends are not likely to be encountered.
Preferably, ball tip 116 is advanced only as far as a 15 point outside the body into which the light guide is to be passed, so that the launch point between the fiber tip and the liquid can be inspected through the tube wall while the light guide is in use.
Where the optical fiber has a diameter between 2d about 300 and 600 u, and the lumenal diameter of the tube ie greater, a6 for example about 1-3 mm, liquid can flow as indicated generally by arrows F within the tube about the fiber while it is being introduced and once it is in place, The inserted fiber confer$ increased 25 rigidity upon the tube, leaving a proximal portion of the tube, into which the fiber does not reach, flexible:
in many applications, suoh as, fox example, lasQr irradiation of a coronary artery, this proximal portion of the tube is the portion requiring the greatest 30 flexibility.
Preferably tho fiber is inserted so that its tip rests in a relatively straight portion of the tube.
and with the fiber placed as nearly coaxially as possible, to provide launch of the energy frost the fiber 1 G . ,._: :~ ... 8 J U 4 : :~ ~ P z..S :* F I ~ H E.: R I C H A R D S 4 N P~
o tip as nearly coaxially with the tube as possible, A
centering device at the tip of the fiber can help to maintain the coaxial relationship; and a fiber made, for ex~pZe, of a quartz having a low index of refraction can be used to help direct the light principally in a longitudinal direction at the point of launch.
In an alternative embodiment, shown iri Fig. 14, the light guide includes a tube, shown generally at 110.
whose wall llb encloses a lumen 124 which is filled with liquid 12~, Wall 116 includes outer layer i20, and inner layer 118. Inner layer 118 has a reflective surface defining lumenal surface 122 of tube 110. inner layer 118 can be made of a metallized materials containing, for example, aluminum or silver; or inner layer 118 can be made of a reflective polymer, Outer layer 120 is formed of material having suitable mechanical properties, so that tube wall 116 has structural strength as well es flexibility, as described above r~enerally with roferenee to Figs, 1 and 2 and Fiqs, 10 and 11, A tube made of such materials and filled with liquid can be bent through curves of small radius without kinking or substantially distorting the cross-$eetional geometry of the tube, and can work as a light guide for delivery of laser energy.
z5 In an alternative embodiment, showy in Fig. 15, apparatus is shown generally st 210 combining a liquid filled light guide of the invention with a balloon catheter adapted to cooperate with the liquid light guide, The light guide inoludes a tube 211 whose wall 21~ has a lumenal surf ace 222 surrounding a lumen 224 that can be filled with liquid 22s. The wall 216 and the liquid 226 are selected as described above with reference to Figs. 1 and 2 to have optical characteristics such that the liquid 226 and the waht 1 C~ . ~ ==a_ 8 ~ O 4 : .~ LI Y 2~i ~: F I S H ~ R I C Ii A R D S O N

216 together from a liquid core Iight guide; laser energy directed into the distal end (not shown in Fig.
15) of liquid filled tube 2~,1 passes within lumenal space 224 toward proximal end 31a of tube 311, from which a portion 4f the light emerges, as indicated generally by arrow 0. Tube 211 is contaf.ned in generally coaxial relation within a catheter tube 230 so that a space 234 is contained between catheter wall 230 and tube wall x16, proximal tube end 212 i$ affixed to to proximal end 232 of catheter 231 in annular sealed relation at 213. As in a conventional balloon dilation catheter, catheter wall Z30 includes an expandable wall portion 232, $o that when fluid is introduced under pressure into the space 234, the expandable portion 232 1S o~ wall 231 swells or inflates to a configuration such as that for example shown in Fig, 15.
Adaptation of a balloon dilation catheter and oombin,ation o! it with a liquid core light tube as il~.usxrated for example in Fig. 15 can be used far 2o combination balloon/laser angioplasty as follows. The catheter, with the balloon deflated, containing the light tube can be inserted to the site where angioplaety ' is to be carried out, using a guide wire within the lumen of the light guide if desired, When the site to 25 be treated, such as ari athe~roma, is reached, laser energy can be directed thrauqh the light guide onto the site to ablate a portion of the plague to form a channel sufficient to permit passage of the Cathetex. Then the catheter can be inserted through the channel to bring 30 the exandable balloon portion into the angioplasty site, and fluid can b~ introduced into the balloon to cause it to inflate and expand the blood vessel at the site as in cenventional balloon angioplasty. Finally the balloon can be deflated aad the catheter removed.

1 G , , ; :~i.. G ~ G 4 : 3 G P 2~Z :*. F I S H ~. R I C H A R D S O N F~._:~
G
2~U1336 -~ 2 4 Zn another embodiment, shown in Fig. 16, an area of the lumenal surface of a vessel wall can bo treated with diffuse 7,ight directed to the site through a liquid filled light guide according to the invention.
In this embodim~nt the light guide includes a tube 3i6 constructed of a materials selected in part to provide a high degree of internal reflection at the lumenal surface 322 when tube 316 is filled with a suitable liquid, and in part to provide structural strength and io flexibility so that the li.quid~filled light guide can be bent through Curves o~ small radius without kinking or substantially distorting the cro$s-sectional geometry of the tube, as described above with reference to Figs, 1 ~d ~ Qr Figs. 10 and 11. Contained Within tube 316 in generally coaxial relation is an inn~r tube 330 having bore 334 through which a conventional guide wire can be passed. Inner tube 330 is constructed of materials selected also in part to provide a high degree of reflection at the outer surface 332 when tube 316 is 2o filled with a suitable liquid 32b, and in part to be strong and flexible, Affixed to the proximal end 336 of inner tube 330 is an end cap 340 having bore 342 aligned with inner tube bore 334, through which a conventional guide wire can pass. End cap 340 is generally similar z5 to end caps d~scribed above with reference to Fige. 4 through 6. A generally cylindrical portion 344 of and cap 340 is affixed to a flange 346, which Can be constructed of the same material as tube 316. An earpandable sleeve 350, of a material transparent to the light to be delivered to the site, is affixed in annular sealed relation at one end 352 to the proximal and 312 of tube 316 and at the other end 354 to the proximal end of glange 346, so that sleeve 350 dorms a transparent portion of the wall of the light tube surrounding a~

1 ~ . ~ :~ . ~ ~ « 4 : :~ ~ P 2.d ~ F I S H '.~ R I C H A R L'1 S O N F~.~:a 1 2t~01,~3~
space 3s6 proximal to the tube end 312.
A conventional balloon angioplasty generally praduces a dilated portion of the vassal in which the lumenal surface contains cracks and fi~s$ures. These cracks and fissures fill with blood and other matter contained within the vessel, Often, after a time, this matter disperses or is dislodged from the cracks and fissures, and the dilated portion of the vessel collapses, forming a restenosis at the angioplasty 1o site. The matter can be caused to remain in the cracks for a greater time, delaying the collapse of the vessel and the reatenosis, by denaturing the material, for example by application of heat, so that the material forms in effect a mortar in the cracks, The matt~r can be heated and denatured by, for example, irradiating the dilated vessel wall with diffuse light energy, A liquid filled light guide constructed according to the invention and having a transparent wall portion as illustrated for example in Fig. 16 can be used to provide such an irradiation of the inner wall of a vessel following balloon angioplasty as follows.
Following balloon angioplasty the balloon catheter is withdrawn, and, while the cracks and fissures are still filled with matter, the liquid filled light guide is zs inserted, over a guide wire if desired, so that the transparent portion of the wall of then light guide rests within the dilated portion of the vessel. Then further liquid is introduced under pres$ure through the lumen 32~ o~ the light guide, expanding the expandable 3a transparent wall portion 350 within the dilated portion of the ve$sel. Then light is directed through the lumen 324 of the light guide from the distal end (not shown in Fiq. 15) toward the proximal end 312, from which a portion of the light emerges into the liquid-filled 1C~. ~. 8~ «4: ,j~ F'T~i FISH '.~ RI CHARDSCiN
_.- .r, ~U1336 space 3~6, as indicated gen~rally by arrows 0. Because the light can pass outward through expandable transparent wall poxtion 350, the light is not guided lengthwise in the portion of the tube surrounding liquid-filled space 356, and the light leaks outward diffusely from the tube through transparent expanded wall portion 350, as indicated generally by arrows D.
The leaking light oan th~n be absorbed by the lumenal portions of the vessel wall surrounding the expanded portion 350 of the light guide, where the light can denatur~ the matter that has collected in the cracks and fissures of the iruser vessel wall, having the effect of mortaring the wall and helping to prevent its collapse.
Other Embodiments Other embodiments are within the following claims. For example the liquid and the material of the inner wall of thQ light guide can be select~d from any of a variety of materials, provided the tube wall has suitable mechanical properties and provided the indices 2o Qf refraction of at zeast an inner layer of the wall and of the liquid diff~r relatively so that they cooperate to provide a light guide effect. The liquid acrd the inner wall material preferably are selected to maximizQ
the ratio of the indices of refraction of the liquid and zs of the iru~er wall of the tube. Where the wall material has been selected. the index of refraction of the liquid must be at lea$t as high as that of thQ selected wall material: sad, conversely. where the liquid has bean selected, the index of refraction of the inner wall 3o material must be dower than that of the selected liquid.
as discussed generally above, Where a flow of the liquid into the milieu beyond the proximal end of the light guide is employed to provide a temporary liquid--core, liquid-clad light 1 C~ . .r .. ~ 9 C~ 4 : :~ ~ Y 2~I m F I S I-I a, R I C H A R D S O N F~- r ~61336 guide between the proximal end of the tube and the target site, the selected liquid must have an index of refraction greater than that of the milieu. The liguid can be introduced into the tube by means, for example.
of a syringe or of a pump, such as for example a peristaltic pump, configured and arranged so that it is capable of providing a flow of fluid without introducing air bubbles into the tube, preferably wher~ the means gor pxoYiding the flow of fluid is capable of producing 1o high pressures, conwentiQnal means are provided for shutting off the flow when the pressure exceeds a level of safety, Any of a variety of radiographic contrast media can be used, including a nonionio contrast medium such as. for example, contrast media commercially available as Hexabrixe or Omnipaque~, or an ionic contrast medium such as, for example, contrast media commercially available ae.Renographin 76~, or Angiovistm.
Admitting a fiber into the light guide will 2p make much less flexible that portion of the light guide containing the fiber; in circumstances where great flexibility is needed principally in a distal portion of the catheter, such as, for example, where the site to which the laser energy is to be delivered is in a as coronary artery, the fiber can be admitted only as far as a point distal to the portion of the tube in which great flexibility is required. This can provide for a straightfQrwaxd launch of energy into the xiquid light guide, and can shorten the distance within the liquid light guide through which the energy is transmitted.
thereby reduoing los~aes and increasing the transmis~s~.on ef~icisncy of the delivery apparatus,

Claims

1. A flowing fluid laser catheter system for transmitting laser energy from an extracorporeally located laser generating device to a mass of target matter located within a mammalian body, said catheter system comprising:
a flexible catheter body having a proximal end, a distal end, an outer surface and a luminal surface, the luminal surface of said catheter body defining a fluid flow lumen which extends longitudinally through at least a portion of said catheter body, said fluid flow lumen having a first diameter;
a laser transmitting optical fiber extending longitudinally through a proximal portion of said fluid flow lumen, said optical fiber having a proximal end, a distal end and an outer surface, said optical fiber having a second diameter which is smaller than the first diameter of said fluid flow lumen, the distal end of said optical fiber being disposed within said fluid flow lumen a spaced distance proximal to the distal end of said catheter body, with said outer surface of said optical fiber not contacting the luminal surface, thereby providing a generally annular fluid flow space which laterally surrounds said optical fiber;
a fluid inflow opening formed in said catheter body at a location proximal to the distal end of said optical fiber to permit infusion of a laser transmitting liquid into said fluid flow lumen;
a fluid outflow opening formed in said catheter body at location distal to and in alignment with the distal end of said optical fiber;
a flow of laser transmitting liquid being infused in the distal direction through said fluid inflow opening, through said generally annular flow space and out of said fluid outflow opening, concurrently with the transmission of laser energy through said optical fiber such that said laser energy is launched from the distal end of said optical fiber into the flow of laser transmitting liquid and is carried within said flow of laser transmitting liquid out of said fluid outflow opening and into contact with said target matter.

2. The flowing fluid laser catheter of claim 1 wherein the optical fiber is coaxially centered within the fluid flow lumen of said catheter body.

3. The flowing fluid laser catheter of claim 2 further comprising:
a centering apparatus for holding said optical fiber in a substantially coaxially centered position within said fluid flow lumen.

4. The flowing fluid laser catheter of claim 1 wherein said second diameter of said optical fiber is about 1-3 mm.

5. The flowing fluid laser catheter of claim 1 further comprising:
a Y-connector positioned on the proximal end of said catheter body, said Y-connector having a first furcation through which said optical fiber is inserted, and a second end and a second furcation forming said liquid inflow opening through which said laser transmitting liquid is infused.

6. The flowing fluid laser catheter of claim 1 further comprising:
a bubble filter connected to said catheter lumen for filtering gas bubbles from said laser transmitting liquid.

7. The flowing fluid laser catheter system of claim 1 wherein:

said luminal surface has a refractive index N w;
said laser transmitting liquid has a refractive index N f; and the refractive index (N f) of said laser transmitting liquid being greater than the refractive index of said luminal surface (N w).

8. The flowing fluid laser catheter system of claim 7 wherein the ratio of said refractive index of said liquid N f to the refractive index of said luminal surface N w is greater than 1Ø

9. The flowing fluid laser catheter system of claim 7 wherein the ratio of said refractive index of said liquid N f to the refractive index of said luminal surface N w is greater than 1.05.

10. The flowing fluid laser catheter system of claim 7 wherein the ratio of said refractive index of said liquid N f to the refractive index of said luminal surface N w is greater than 1.10.

11. The flowing fluid laser catheter of claim 7 wherein the value of N f is at least about 1.46.

12. The flowing fluid laser catheter of claim 7 wherein the value of N w is at least about 1.33.

13. The flowing fluid laser catheter of claim 1 wherein the luminal surface of said fluid flow lumen is formed of fluorinated ethylenepropylene.

14. The flowing fluid laser catheter of claim 1 wherein the luminal surface of said fluid flow lumen is formed of fluorinated polypropylene.

15. The flowing fluid laser catheter system of claim 1 wherein at least a portion of said fluid flow space between said luminal surface and said optical fiber is sufficiently large to permit passage of a guide wire therethrough, next to said optical fiber.

16. The flowing fluid laser catheter of claim 1 further comprising:
a guide wire passage lumen extending longitudinally through said catheter body to permit passage of a guide wire therethrough, said guide wire passage lumen being formed separately from said fluid flow lumen.

17. The flowing fluid laser catheter of claim 1 wherein said first diameter of said fluid flow lumen is about 1-3 mm and wherein said fluid outflow aperture has a diameter of about 500 microns.

18. The flowing fluid laser catheter of claim 1 wherein said luminal surface comprises a reflective layer.

19. The flowing fluid laser catheter of claim 18 wherein said reflective layer is bonded to said luminal surface.

20. The flowing fluid laser catheter of claim 18 wherein said reflective layer comprises a metallized layer.

21. The flowing fluid laser catheter of claim 1 wherein the portion of said catheter which extends distally beyond the distal end of said optical fiber is bendable into a curve having a radius of curvature of 20 mm without substantial change in the cross-sectional shape of said catheter body.

22. The flowing fluid laser catheter of claim 1 wherein the portion of said catheter which extends distally beyond the distal end of said optical fiber is bendable into a curve having a radius of curvature of 10 mm without substantial change in the cross-sectional shape of said catheter body.

23. A laser catheter system comprising the flowing fluid laser catheter of claim 1 further in combination with a laser generating device coupled to the proximal end of said optical fiber.

24. The laser catheter system of claim 23 wherein said laser generating device is a pulse dye laser.

25. The laser catheter system of claim 23 wherein said laser generating device is an excimer laser.

26. The flowing fluid laser catheter system of claim 23 wherein said laser generating device is an Holmium laser.

27. The flowing fluid laser catheter system of claim 23 wherein said laser generating device is an Erbium YAG laser.

28. The flowing fluid laser catheter of claim 1 further comprising:
a dilation balloon positioned on the outer surface of said catheter body; and a balloon inflation fluid channel extending through said catheter body for passing balloon inflation fluid into and out of said balloon.

29. A flowing fluid laser catheter for delivering laser energy from a laser generating device to a target location within a mammalian body, said catheter comprising:
an elongate flexible catheter body having a distal end, a proximal end, an outer surface and a hollow lumen defined by a luminal surface extending longitudinally therethrough;
a laser transmitting optical fiber disposed within a proximal portion of said catheter lumen such that the proximal end of said fiber is coupleable to a said laser generating device and such that the distal end of said fiber terminates within the catheter lumen at a launch point proximal to the distal end of said catheter lumen;
a liquid inflow opening proximal to said launch point for infusing a laser transmitting liquid through said catheter lumen;
a liquid outflow opening formed distal to said launch point for permitting said laser transmitting liquid to flow out of said catheter lumen;
a fluid flow restricting endcap positioned on the distal end of said catheter lumen, said endcap having said liquid outflow opening formed therein, the size of said liquid outflow opening being smaller than the transverse dimension of said catheter lumen so as to restrict the outflow of liquid from the distal end of said catheter lumen; and whereby laser energy is transmitted from said laser generating device, through said optical fiber, and into a flow of laser transmitting liquid being infused through said lumen and out of said outflow opening.

30. The flowing fluid laser catheter of claim 29 wherein said optical fiber has a transverse dimension less than the transverse dimension of said lumen, thereby providing a space between said luminal surface and said optical fiber such that said laser transmitting liquid entering said inflow opening may flow through said space, through said lumen, and out of said outflow aperture.

31. The flowing fluid laser catheter of claim 29 further comprising:

a centering device for holding said optical fiber in a substantially co-axial position within said catheter lumen, thereby providing for substantially co-axially directed launch of laser energy from the distal end of said fiber into laser transmitting liquid being infused through said catheter lumen.

32. The flowing fluid laser catheter of claim 30 wherein said optical fiber has a transverse dimension of about 300-600 microns and said catheter lumen has a transverse dimension of about 1-3 mm.

33. The flowing fluid laser catheter of claim 29 further comprising:
a Y-connector positioned on the proximal end of said catheter body, said Y-connector having a first furcation through which said optical fiber is inserted, and a second furcation forming said liquid infusion opening through which said laser transmitting liquid is infused.

34. The flowing fluid laser catheter of claim 29 further comprising:
a bubble filter for filtering gas bubbles from said laser transmitting liquid.

35. The flowing fluid laser catheter of claim 29 wherein:
said luminal surface has a refractive index (N f);
said laser transmitting liquid has a refractive index (N w); and the refractive index (N f) of said luminal surface being greater than the refractive index of said liquid (N w) and the ratio (N f /N w) of the refractive index (N f) of said luminal surface to the refractive index of said liquid (N w) being greater than 1Ø

36. The flowing fluid laser catheter of claim 29 wherein:

said luminal surface has a refractive index (N f);
said laser transmitting liquid has a refractive index (N w); and the refractive index (N f) of said luminal surface being greater than the refractive index (N w) of said liquid and the ratio (N f /N w) of the refractive index of said luminal surface (N f) to the refractive index of said liquid (N w) being greater than 1.05.

37. The flowing fluid laser catheter of claim 29 wherein:
said luminal surface has a refractive index (N f);
said laser transmitting liquid has a refractive index (N w); and the refractive index (N f) of said luminal surface being greater than the refractive index (N w) of said liquid and the ratio (N f /N w) of the refractive index of said luminal surface (N f) to the refractive index of said liquid (N w) being greater than 1.1.

38. The flowing fluid laser catheter of claim 35 wherein the value of N f is at least about 1.46.

39. The flowing fluid laser catheter of claim 35 wherein the value of N w is at least about 1.33.

40. The flowing fluid laser catheter of claim 35 wherein the value of N f is about 1.46.

41. The flowing fluid laser catheter of claim 35 wherein the value of N w is about 1.33.

42. The flowing fluid laser catheter of claim 29 wherein the luminal surface of said catheter lumen is formed of fluorinated ethylenepropylene.

43. The flowing fluid laser catheter of claim 29 wherein the luminal surface of said catheter lumen is formed of fluorinated polypropylene.

44. The flowing fluid laser catheter of claim 29 wherein sufficient space exists between said luminal surface and said optical fiber to permit passage of a guidewire through said catheter lumen, next to said optical fiber.

45. The flowing fluid laser catheter of claim 29 further comprising:
a separate guidewire passage lumen extending longitudinally through said catheter body to permit passage of a guidewire therethrough.

46. The flowing fluid laser catheter of claim 44 wherein said catheter lumen has a transverse dimension of about 1-3 mm and wherein said liquid outflow has a diameter of about 500 microns.

47. The flowing fluid laser catheter of claim 29 wherein said luminal surface comprises a reflective layer.

48. The flowing fluid laser catheter of claim 47 wherein said reflective layer is bonded to said luminal surface.

49. The flowing fluid laser catheter of claim 47 wherein said reflective layer comprises a metallized layer.

50. The flowing fluid laser catheter of claim 29 wherein the portion of said catheter which extends distally beyond the distal end of said optical fiber is bendable into a curve having a radius of curvature of 20 mm without substantial change in the cross-sectional shape of said catheter body.

51. The flowing fluid laser catheter of claim 29 wherein the portion of said catheter which extends distally beyond the distal end of said optical fiber is bendable into a curve having a radius of curvature of 10 mm without substantial change in the cross-sectional shape of said catheter body.

52. The flowing fluid laser catheter of claim 29 further in combination with a laser generating device coupled to the proximal end of said optical fiber.

53. The flowing fluid laser catheter of claim 51 wherein said laser generating device is a pulse dye laser.

54. The flowing fluid laser catheter of claim 51 wherein said laser generating device is an excimer laser.

55. The flowing fluid laser catheter of claim 51 wherein said laser generating device is an Holmium laser.

56. The flowing fluid laser catheter of claim 51 wherein said laser generating device is an Erbium YAG laser.

57. The flowing fluid laser catheter of claim 29 further comprising:
a dilation balloon positioned on the outer surface of said catheter body; and a balloon inflation fluid channel extending through said catheter body for passing balloon inflation fluid into and out of said balloon.

58. A flowing fluid laser catheter system for delivering laser energy to target matter located within a mammalian body, said catheter comprising:
an elongate, pliable catheter body having a proximal end, a distal end and at least one lumen extending longitudinally therethrough, said lumen being defined by a luminal surface;
an outlet opening formed in the catheter body such that fluid flowing through said at least one lumen may pass out of said outlet opening, a source of liquid radiographic contrast medium which is unmixed with other oxygen-bearing fluid and which is connected to said at least one lumen and useable to pass a flow of liquid radiographic contrast medium through said lumen, out of said outlet opening and into contact with said target matter;
a laser transmitting member which is connectable to a laser generating apparatus, said laser transmitting member being operative to pass laser energy from said laser generating apparatus into radiographic contrast medium which is flowing through said at least one lumen, such that the laser energy will be carried by said flow of radiographic contrast medium out of said outlet opening and into contact with said target matter.

59. The catheter system of claim 58 wherein said source of radiographic contrast medium includes apparatus for infusing said radiographic contrast medium through said at least one lumen and out of said outlet opening with sufficient force to displace body fluid from the area between said outlet opening and said target matter, thereby creating a column of said radiographic contrast medium which carries said laser energy from said outlet opening into direct contact with said target matter.

60. The catheter system of claim 58 wherein the source of liquid radiographic contrast medium comprises a source of an iodinated contrast medium.

61. The catheter system of claim 58 wherein the source of liquid radiographic contrast medium comprises a source of an ionic contrast medium.

62. The catheter system of claim 58 wherein the source of liquid radiographic contrast medium comprises a source of a nonionic contrast medium.

63. The catheter system of claim 58 wherein at least a portion of said catheter body may be bent into a curve having a radius of curvature no larger than 10 mm without changing the cross-sectional shape of the catheter body at the location of said curve.

64. The catheter system of claim 58 wherein at least a portion of said catheter body may be bent into a curve having a radius of curvature no larger than 20 mm without changing the cross-sectional shape of the catheter body at the location of said curve.

65. The catheter system of claim 58 wherein the source of liquid radiographic contrast medium comprises a source of a contrast medium which has a refractive index of and said luminal surface has a refractive index n W, the refractive index n f of said contrast medium being greater than the refractive index n W
of said luminal surface.

66. The catheter system of claim 65 wherein the ratio of of to n W is greater than 1Ø

67. The catheter system of claim 66 wherein said ratio is about 1.05.

68. The catheter system of claim 67 wherein said ratio is about 1.1.

69. The catheter system of claim 58 wherein said laser transmitting member comprises an optical fiber having a proximal end which is coupleable to said laser generating apparatus and a distal end, said optical fiber extending through a portion of said at least one lumen such that the distal end of said optical fiber is positioned within said at least one lumen a spaced distance proximal to said outlet opening such that laser energy will pass from said optical fiber into the radiographic contrast medium flowing through said lumen and said laser energy will then be carried by said flow of radiographic contrast medium through the remainder of said at least one lumen, out of said outlet opening, and into contact with said target matter.

70. The catheter system of claim 69 further comprising fiber centering apparatus which will hold at least the distal end of said optical fiber in a substantially centered position within said at least one lumen such that a fluid flow space surrounds at least the distal end of said optical fiber.

71. The catheter system of claim 70 wherein said source of liquid radiographic contrast medium is connected to said catheter body at a location which is proximal to said optical fiber supporting apparatus such that radiographic contrast medium will flow through said fluid flow space and laser energy may pass from the distal end of the fiber, into said flow of radiographic contrast medium and will be carried by said contrast medium out of said outlet opening and into contact with said target matter.

72. The catheter system of claim 71 wherein the distal end of said optical fiber is aligned with said outlet opening.