CA2340237C - Indwelling heat exchange catheter and method of using same - Google Patents

Abstract

A catheter is adapted to exchange heat with a body fluid, such as blood, flowing in a body conduit, such as a blood vessel. The catheter includes a shaft with a heat exchange region disposed at its distal end. This region may include hollow fibers which are adapted to receive a remotely cooled heat exchange fluid preferably flowing in a direction counter to that of the body fluid. The hollow fibers enhance the surface area of contact, as well as the mixing of both the heat exchange fluid and the body fluid. The catheter can be positioned to produce hypothermia in a selective area of the body or alternatively positioned to systemically cool the entire body system.

Description

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-1JS199#~8~455 YNDWELLING TIEAT EXCIiANGE CATHETER

~ tETHOD OF USING SAM>r;
Ei~f~.e~tientiQn This inveniioii rclatrs gcneraIly to apparatus and mcthods for producing lieat exchdngc with body tissue, and more specifically to methods and apparatu5 for the hypothcrmie trcatment of a bodv fluid in a body conduit.

Discussion of h ,Prior A

Many of thc advantagcs of hypothetniia arc well known. By way of example, it has bccn found partieularly desirable to lower the teniperature of body lissue in ordcr to reducc the metabolism of the body. In stroke, trauma and several other pathological coniiitions, hypothcrmia also reduecs the petYneability of the blood/brain barrier. It inhibits release of damaging ncurotransmitters and also inhibits calcium-incdiltcd effects. Hypotheitnia inhibits bi-aiia edema and lowers intracranial pressure.

In the past, hypothermie treatment has been typically addressed systemically, mcaning that the overall tempera.ttire of the entire body has been lowcrod to achieve the advantages noted above. This bas bccn particularly desirable in surgical applications where the rcduccd metabolism has made it possible to niore easily accommodate lengthy operative proeedures. An example of this systcrnic appi=oacli includcs catheters for transferring hcat to or fron, blood llowing ivithin a patient's vossel, .as disclosed by Ginsburg in U.S. Patent No. 5,486,208. A closed loop heat exchange catheter is also disclosed by Saab in U.S. Patent No.5,624,392. A coobina device for whole-body liyperthecmia that utilizes thc circulatoiy 5ystcm of the body is knowm to be more AMENDED SHEEI

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efticient since the entire volume of lhe body is coiZstantl.v perfused with the cold fluid at a caliillaty level.
Likewise, various other means of eoolii-ig the body have bcen tried with coolin;
blwikcts, ice waterbla.clder lavages, ice ba=.hs, esopliageal catheters and their assaciLxted inethods. All of thcsc dcvices requirc a considcrable time to cool the body sin.ce the primary hcat transfcr occurs through the skin or the skull. A more efficicnt body cooling device that can quickly cool and accurately control the body temperature is required.
The systemic approach is not always advantageous when the beneficial effects are desired locally at the focus o.f tlic operative proccdure and only thc disadvantages of hypothcnnia are felt tliroughout t:ic remainder of the body.
More recent focus has been directed to producing hypothermia in localized areas of ihe body, teavina lhe remainder of the body to function at a non-nal body tcinipcraturc. Thcsc localizcd applications of hyhotllcrrnia havc hccn cxtcrnal, rc]ying for cxample on cooling helmets or cooling ncck collars to produce localizcd hypothermia for the brain.

Summary of the Invention A heat excliange catheter and rnethod of operation are itichtded in the prescnt S.tlvetttton, The method is adapted to produce hypotheimia or liyl;ertherrnia, typically in a selected portion of the body without substantially varying the temperature of the remaining portions of the body. The selected body portion will usullly be associated with a body conduit which conveys a body fluid to the selected body portion.
Of particular interest are the organs of the body which are comrnonly nourished and maintained by a flow of blood in the arterial systein. For example, a flow of blood is introduccd to thc brain througli the carotid artery. Of course the tziiipcrature of this blood is usually at the normal body teznpcraturc.
By positionutg a heat exchange catheter in the body conduit, heat cati be added to or removed fionl the body fluid to heat or cool the selected body portion.
For AMENDED SHEET

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cxample, the heat exchan$e catheter can be disposed in the carotid artery where the artcrial blood tYowing to the brain can be cooled. The flow of cooled blood to the brain t=editces the temperature of the brain thereby rc;sulting in cerrbral hypotherenia.
jtnportaiitly, this tcmpcraturo reduction occurs primarily and selectively in the brain;
the rentaining pottions of the body maintain a generally normal body tempe.rature. In accordance with this mcthod, thc sclcxtcxi bociy portion, such as the brain, can be cooled thcrcby providing the advantabes associated with hypothermia for t.his body portion, The remainder of the body, suclt as the portions other than the brain, do not experience the reduction ii. tenmperature and thereforc arc not suscc.~ptible to the disadvantages of hypothermia. Furthermore, the invcntion is intcndcd to remotely alter tenlperature in a region other than the point of introduction into the body. This is different than devices intended for systeniic teniret-ature cozitrol.
Scvcral factors are of interest in effecting heat transfer in a heat exchatzgert These factors include, for example, tlie convection heat transfer coefficient of the two fluids involved in the heat exchaage, as u/cll as the thcrrnal eonduetivity and thicl;iiess of the barrier between the two f7uids. Vthcr factors includc tho re.ative temperature diffcrential between the fluids, as well as the cotitact area and residcncc time of hcat transfer. The Reyitolds rttartber for each fluid streatit affects boundaty layers, turbulence and larninar flow:
Notwithstanding the need for localized hypothernzia, there will always be those procedures which call for systcmic hypothcrmia. Many of the advantagzs associated With thc prcacnt invention will greatly fa.cilitate those proccdures, for example, by dccrcasing the numbcr and complexity of operative steps, increasing the heat transfer capacity of the device, and addressing other concerns such as the formation of blood clots.
In one aspect of the invention a catheter is provided with an elongate configtiration, a proximal end satd a distal end. An outer tube having a first Jumc7l extends between the disttl end and proximal end of the catheter, and an intacr tube having a second lumen is disposed within the first lumen of the outer tube.
Fortions of the itlner tube ciefule a first flow patli exteuding along the second lumen, ~,hile puriions AMENDED SHEET

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of Cne tubcs cleGne a second flow patlt extcnding between the first tube aud thc seeond tube. A plurality of hollow fibers provide fluid cornmunication between the first and second flow paths, and a heat eachange fluid is disposed in the hollow fibers to cool the fibcrs.
In anothcr aspect of the uivention, a method for inaking a heat exchange catheter includes the steps of providing first and sccond tubes having fiLst and sccond lumcns, respectively. A plurality of iiollow fibers are connected betwecn a first flow path extending along tho socond lumen and a second flow path extending along the fii-st lumcn outwardly of the second tuhc. Tiic method further coinprises the stcp of insuring that the second tuoe is axially or rotationally movable relative to thc first tube in order to vary the configuration of the hollow fibers.
In a further aspect of thc invention, a method for opcrating a heat excliange catheter includcs the steps of inserting iiito a body conduit the catheter with art inncr tube disposed within an outer tube and defining a first tlow path interiorly of the inner tube anci second flow path betwcen the iiuier tube a d the outcr tube. This inseited cathctcr also includes apiuralit3, ofhollow fibcrs dispQscd in fluid conttnizicationwith the first and second flow paths. The :ncthod further includes steps for creating a flow of heat exchange fluid throush the i~rst anci second flow patlis, and moving thc inner tube relative to the outcr tubc 'Lo change the profile of the hollow iibcrs.
In a furthcr aspcot of the invention, a heat exchange catheter includes an elungate shall with fust poztions deflning an inlet lunien altd second portions deFining an outlet Iu171cn, A first manifold is disposed in fluid communication with the inlet lumen and a second manifold disposed in fluid communication with the outlet ]tuuen.
A phtrality of holiow fibers are disposed between the manifolds in fltiid commuiucation with the inlet and outlct lumens.l'he catheter is adaptcd to rcocivc a heat excliange fluid aud to dircet the heat exchange fluid through the hollow fibers to exchange heat throui;h the hollow fibers.
In still a furtlicr aspcct of the invention, a catheter is adapted to exchange heat with the body fluid flowing in a first direction through a body conduit. The catheter includes a shaft having an input lumen and an output lumen. A plurality of hollow AMENDED SHEEr npcdCA 02340237 2001-02-12 } }.
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fibers defiy ic a hcat cxchange region and collectivcly dcfino an output surface of the hcat exchange region. The input lumen of the shaft is coupled to the hollow fibers at a first location whilc thc output ltunen of the sbaft is coupled to the hollow fibers at a sccond location disposed in the first dircction ;Crom the first location.
Another aspect of the invention includes a method for exchanging heat witli a body fluid in a body conduit. In this casc, a cathctcr is provided with a plurality of hollow heat exchange fibers oxtcndtng in fluid comrnuzticatinn with an inlet lumen and an outlet lumen of thc catheter. 3'he heat exchange fibcrs collectivelv define a first cavity in heat transfcr relationship with a body fluid in a body conduit.
In aiz additional aspect of the ini.yention, an operative area of tl-ie catheter is sized and eonfigured for disposition in a vessel containing blood. The operative area is adaptcd to perform a pre&,termined funclion, and the blood in the vessel has a tcndency to form elots. In this aspcct of the invention, the catheter is provided with a snare disposed relative to the operative area attd beiuQ operable fi=om a proximal end of the cathcter to rnove frorn a low-proCic state facilitatutg insertion of the catheter, to a hig.,~t-profile state facilitating thc capture ofblood clots.
In still a Carther aspect of the invention, a heat exchange cathctcr is adapted for eooling tiie blood of a paticnt. 'i'he catheter includcs a heat oxehange region with a plurality of fibers each having a hollow configtiration. A heat exchange l7uid is disposcd in the hollow fibers to cool tlle fibers and a coating is disposed on the outer surface of tho fibers to inhibit foimation of blood clots.
In a further aspect of the invention, a heat exchange catheter of ttse present invention includes a shaft having an axis, a fluid inlet lumcri and a (luid outict lumcn each extending generally between a proximal and end and a distal cnd of the shaft. A
hub disposed at the proximal end provides access to the fluid lumens. At lea.st one balloon is provided in aheat exchange rcgion at the distal c.-nd of the shaft, the balloon wall providing the bazricr bctween the two fluids. With the catheter positioned in contact with the body fluid within the conduit, heat transfer occurs across the batloon wall. The relative temperature di.fferenLial is facilitated with countcrcurrc;nt flow betwc;e.n the two fluids.

S-HEET
}CA 02340237 2001-02-12 D-lwSOPAMD

In one aspect of the invention, a first balloon is disposed at the distal end of il-ic shaft and dcfines with the shaft aii inflatable first cavity. Portions of the shaft define a first uiltit hole extending in fluid communication between the first lunicn and the first cavity. Portions of the sliaft dcfinc a first outlet holc extending in fluid comntunication betweeu the fu'st cavity aitd the flLid outlet lumen. A second balloon disposed relative to th efirst balloon defines with the shaft an inflatable second cavity with portions of thc shait defining a second inlct holc betwe~,~n the fluid inlet luuten and tho second cavity, Portions oftho shaft also define a second outlct hole in fluid communication with the second cavity and the fluid outlel lumcn. Typically, the first balloon will be disposed distally of the second balloon and the first inlet hole will be largcr than the sccond inlet hole. An elastomcric matcrial covering a valley or volun-ie between the first balloon and the second balloon may be provided to prcmiote mixing necessary for efficicnt heat excbange yet minimize turbulcncc and shear which can be daniasing to blood.
In an acl:Iitional aspect of the invention, a meQlod for exchanging heat with a body fluid in a body conduit nicludes the step of introducing into the body conduit a catheter having an inlet lumen and an outlet lumen. The catheter is provided with a first cavity and a second cavity eacfi in heat tratisfer relatioziship with lhc body fluid iu the body c.onduit. A het exchange fluid is introduccd into thc inlet lunten and through an inlct hotc into each of the fi-st cavity and the second cavity. An excha.nge of heat theti occurs between the heat exchange Iltud in te first and seconcl cavitics and the body fluid in the body coiiciuit. Ultimately, the heat exchange fluid is removed through an outlet Iiolc and the outlet ltuncn associated wit each of thc first cavity and the second cavity.
Creating non laminar flow iti the one or both of the heat exchange fluid and the body fluid will improve lieat transfer efficio',ncy. H cat transfer can also bc cffcctcd by various stntchtres which cither enhaiicc or inhibit tu.Mbulence in the fluids.
Thcsc and other features and advauitabes of the invention will be better understood with a description of the prefcrrcd cmbodimonts of the invention and rcfcrcnce to the associated drawings.

AMENDED SHEET

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_7_ Dxscription of the Drawings Fig. I is side clcvntion view of a patient lying in a prone position with a Izeat cxchange cathetet' of the present invention appropriately inserted to facilitate hypothcrmic treatment of the paticnt's braitl;
Fig. 2 is an enlarged side elevation view showing the vasc'alaturc associated with the patiztlt's head and brain;
Fi o. 3 is a perspective view partially in sectioii of a heat excliange regior-i of the cathctcr=
Fig. 4 is an cnlargcd axial cross section view of a plarality of balloons disposed in the heat exchangc region of the catheter;
Fig. 5 is a radial cross section vicw of the catheter taken along lincs 5-5 of Fig.
4;
Fig. 6 is a raclial cross scction view siaziilar to Fi,g. 5 of a further c;mbodiment of the cathctcr, Fig, 7 is a perspective vicw of a tllrther embodiuncnt of the catheter wherei.i multiplc balloons are provided with a lougitudinal configuration;
Fi.g. 8 is a radial cross section view taken along lines 8-8 of Fig. 7;
Fig, 9 is an axial cross section vicw taken along lines 9-9 of Fig. 7;
Fig. 10 is a perspective view of the catlieter illustratcd ir. Figure 3 furthcr illustrating sttv.ctUres which ean facilitate tnixing and heat etichange;
Fig. IOA is a perspective view of an embodiment of the catheter haviilg a distal end with a pigtail configuration;
Fig.1 OB is a perspc:-ctive view of the cu.tbctcr illustrated in Fig. l0A with the dista; cnd straightcncd by a stylet 174 to facilitate insertion of tb.-, catheler;
Fig. 11 is a sehematic view of an embodiment including a hcat pipe;
I'ig. 12 is a scilcixiatic vicw, partially in section, of a heat pipo adapted for use in th; cmbodimett t of Fig. 11;
Fig. 13 is a top plan view of carotid ariery braneh ilhistrating one method of operation associated with the catheter;

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Fig. 14 is a top plaii view similar to Fig, 13 and slzo-sving a futtli;:r mcthod of operation xrith thc cathctcr;
Fig. 15 is a t.op plan view of the carotid branch similar to Fig. 13 and showing a furtlier mcthod of operating a heat exchangc cathcter;
Fig, 16 is a radial cross scction of the catheter takeii along lines 16-16 of Fig.
15;
Fig. ] 7 is an axial cross section vicw of a furthcr embodiment of the invcntion iricluding hollow fibers in the heat exchango reoion;
Fig. 18 is a side elevation vicitv siinil2.r to Fi ;ure 17 and illustrating the hollow fibers in a comPactcct configuration; and Fig, 19 is an axial cross scctioii view of the catheter of Figure 17 operatively disposed and configured to permit the hollow fibers to tioat and tmdttlate within a blood stream.
Fig. 20 is a side elevation view partially in section and illustrating a furtlter embodiment of the catheter of (he pn;scnt inventioti;
f ig. 21 is a radial cross-section view taken along the iines 2I-21 of Figure 20;
Fig. 22 is an axial cross-section vieW of the prozimal end of the cathcter illustrated in Figurc 20;
Fig. 23 is an axial cross-section view of the distal end of a further embodiment illustratint; the heat exchatige region in a low-profile state;
Fig. 24 is an axial cross-scction view similar to Figurc 23 and illustrating the heat exchLLigo region in a high-profile state;
Figs. 25-27 illustrate a preferred nzethod for manufacturing thc heat exchange region of a hollow fiber embodimcnt of the cavity;
Fig. 25 is a top plan view of a mat formed of the heat exchange fibers;
Fig. 26 is a perspective view illustrating fomlation of the uiat around the distal eads of thc conccnlric tubes;
rig. 27 is a side elevation view illustrating attachment of the mat assembly to an outer tube of the catheter;
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Fig. 28 is a top-plan vicw of a pat:cnt illustrating portions of the blood aircula"tory system;
Fig. 29-33 illustrate a method for introducing the catlteter of thc present invention;
Fig. 29 is a side clcvation view illustrating a introducing sheRth in a first position removed from the heat exchanoe region;
Fig. 30 is a side clevation view illustratittg thc shcdth in a second position over the heat exchange region of the catheter;
F'ig. 31 is a side elevation view illustrating the catheter and sheath being inserted ia2to an introducer;
Fig, 32 is a sido elevation view illustrating the cathctcr furl:laer inserted with the shcath maintained in the introducer;
Fig. 33 is a s-icic olevation view illustrating rcmoval of'tho sheath to the fust position;
Fig. 34 is a perspective view of a ftirlher embodirnent of the cathctcr inclculing a distal clot filter in a low-profile statc;
Fig, 35 is a pcrspcctivc yicw illustrating the cathctcr of Figure 34 with the clot filter in a high-profile state;
Fig. 36 is a pcrspcctivc view of a catheter with a clot filter having free ends and autoinatically dcployable to a high-profile state; and Fig. 37 is a side elevation view of the catheter of Figurc: 36 with a sheath inaintaining the clot filter in a low-profilc state.

Description of the Preferred F mbodiments and Best Mode of the lnvention A heat exclzange catheter is iliustrated in Figure 1 and desigiiated gcucrally by the reference nunieral 10. Thc catheter 10 is operatively disposcd with respect to a body 12 of a patient ba.ving a groin 14, a head 16, and a brain 18. More speciti:.ally, lhe catheter 10 can be inserted percutaneously through a pi.neture or surgical cut down at the groin 14, acid into the fcinoral artery 21. Following this initial introduetion, the AMENDED SHEET

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-io-catiletcr 10 ean be moved through thc fcnnoral artery 21 and the aortic arch 23, into the co iinon carotid artery 25 best illustratcd in Figure 2. This common carotid artery 25 divides at a carotid branch 27 into an externdl carotid aitery 30, lvhich primarily supplics blood 31 to ttze facc of the patient, and an intetnal carotid artery 32, which primarily supplies blood to the brain ] 8 of the patient, In the concept of this inveution, tlte brain 18 is merely represcntativc of a portion of ihe body 12 of the paticnt, and the arteries 21, 25, 30 and 32 are merely representative of conduits which supplv a body fluid, such as blood, to a selectc:rl porLion of the body 12, sach as thc brain 18. By cooling the body fluid, such as blood 31, in the body conduit, such as thc artery 32, the specific body portion, such as the brain 18, can be selectivciy cooled without significantly affecting the temperature of the rem:uning portions uf the body 12.
Selective hypothemiic trcatmcnt of tho brain 18 is i:titially of partieulat interest as it captures thc advantages of hypothernaia during operative procedures associated With the brain 18 without also capturing the disadvai.itagca of hypothormia with respcct to other areas of thc body 12. '1'hus, a surgeon operating to trcat an aneurysm in the braiit 18, for exarnplc, can initially cool the braiui 18 in order to facilitate that proceiurc.
Tttis selective hy-pothermia will be paiticularly apPrcciatc;d in those surgical rroccduriss wllicb arc primarily directed to the brain 18. Procedures such as stroke, trautna, and othcr brain related injurics will also benefit up to and during from this sclcctive hypothermia Lreatment.
A prcfcrred embodimetit of th c catheter 10 of the present invention is illu trated in Figurc 3 and 4. From this pcrspective view, it can be seen that tlte catheter 10 includes a shaR 40 having an axis 41 which extends bctwcen a proximal ctld 43 and a distal cr.c145. Whon oPcrativoly disposed, a hcat cxchange region 47 at the distal end 45 is operativcly disposed within the body 12, and a hub 50 at the proximal und 43 is disposed outside of the body 12. Within tlic shafZ 40, a plura.ity of lurnens 52 and 54 extcnd in fluid communication with the hub 50 and the heat cxcbange region 47.
A preferred embodiment of the heat exchange region 47 is illustrated in grcater ctctail in Figure 4 wbere inrc e balloons 50, 58 and 61 arc x-idividually, separately and : ~~tl~~fE+~~,rl + CA 02340237 2001-02-12 .................... .
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-ll-axially disposed along the shaft 40. It will be appreciated that although the illustrated embodiment includcs three balloons, a single balloon or double balloon embodiment niay offGr further advantages in a particular procedure, All of the balloons 56, 58 and 61 are illustratcd to have a significantly larger diameter than the shaft 40.
This may not be the case in other emlxxlimcnts. More specifically, it may be desirablc to mdximize the dimcnsion of thc shaft 40 in order to faciliiate flow of the hcat oxehange ~luid. 'f'his will also miiumize the volume of ftuid in the balloon atid promote a niore rapid heat exchange. Tn one such c-mbodinient, the diaineter of thc shafl 40 is in a range between 50 and 90 percent of the diameter of the balloons 56, 58 and 61.
Each of the balloons 56, 58 aud 61 can be fornied froin a piece of sheet ri,aterial 62, 64 aiid 66 whicli is bound or otht,-rwise fixed to the shaft 40 to form a caviCy 63, 65 and 67, respoctivoly, An inlet hole 70 provides fluid communication between the lumen 54 and the cavity 63 of the balloon 56. Simitar uilet holes 72 and 74 are proviclctl for the balloons 58 and 61. In alike manner, an outlet holc 76 can be formed in the wall of the shaft 40 to provide fluid communication betwccn the lumen 52 and the cavity 63 of thc balloon 56, Similar outlet holes 78 and 81 are provided for ti:e ballootts 58 anci 61, respcctivety. With tllis sttucturc, it can be seen that the lumen 54 functions pritnarily as att inlet lumen for a hcat eYchinge fluid which is itlustxated generally as a series of arrotivs designated by the reference numera185.
Initially, the heat exchangc fluid 85 is introduced tlirough the hub 50 (Figure 3) and into tlie iitlet lumcn 54. From the lumen 54, the heat exchange fluid 85 passcs through the inl:t holes 70, 72, 74 and into the respective ballooii cavity 63, 65 and 67.
The lieat excha.ngc; fluid 85 then passes into thc ostlct hole 76, 78, 81 and into thc outlct luincn 52 and the hub 50 to regions exterior of the catheter 10.
After the hcat exchange i7uid 85 is remotely cooled, it is circulated through thu balloon cavitics 63, 65 uid 67 to providc a cold temperature fluid on the inncr surface ofthc shcct matcrials 62, 64 and 66 which form the walls of the balloons 56, 58 and 61, respectivcly. With a body fluid, such as blood 31, flowing exteriorly of the balloons 56;
69 and 61, heat transfer occurs across tho sheet inaterials 62, 64 and 66, respectively.
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74 are provided for the balloons 58 and 61. In alike martner, an vktlet hole 76 can be foirncci in the wall of the shai't 40 to provide fluid cr,tnrnunication between thc lutZten 52 and thw cavity 63 of the baltoon 56. Sirnilar outict holes 78 and 81 zr.c prov;dzd for the balloons 58 and 61:, respcctive.ly. With this structure, it cal, be seen that tlie lun,cn 34 fttnctiotts primai-ily as an inlet luincn for a heat excnange iluicl which is il3ustrttted generally as a scrics of arrows designated by the reference aiumcral 85.

Initially, the hcat cxchanbe fluid 85 is introduced tnrough the hu'a 50 (Figurc 3) and into the inlet lumen 54, From the lumen 54, the heat exchanne fluid 35 passes through the inlt;t hitles 70, 72, 74 and into thc respective balloon cavity 63, 65 al:d 67. The heat exchange fluid 85 then passes into tlte outlct hole 76, 78, 81 and into tht outlet lumen 52 and lhc hub 50 to regions cxicrior of the catheter 10.

At'tcr ihc heat cxcliange fluid 85 is resnotely cooled, it is circulated througn the b11{oon cavities 63, 65 and 67 to provide a cold terr.pe:aturc fluid on the inner surface of the shoet mat_rials 62, 64 and 66 which form the walls of the balloons 56, 58 and 61, respectivcly. With a bodv fluid, such as blood TI, tlowing cxteriorlvof tlte balloons 56, 68 and 61, heat tx,3rksfi.r c)cc:urs across the ~hcct materials 62, (54 and 66, respectively.

It can be appreciatcd th3t this circulation of the heat exehanp lluid 85 eatl hc foizned with any struclarc of the sltaft 40 which provides two lttrnens, suclz a.,; tht lumens 52 and 54, cach of which can have access to thc balloon cavities, such as tlie cavities 63, 65 and 67. In one embodiment of the shaft 40 illustrated in T'igure 5, a septum 9tJ is provided which separates the cylindrical sltaft 40 inlo two equally sized lumens 52 and 54. In the embolimcnt of Figurc 6, the cylindrical slizft 40 is provided with a cyl:t:dricai septum 92 which provides the lumcn 54 with a circular cross section and the lurncn 52 witla a moon-shaped cross scction, in sttch ar1 :rribo~ii.tnent, thc lumen 34 must be cic;Cined off-axis from the sraft 40 in order to ftavc access to the baiioon cavities, such as the cavity 63.

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One of tbe udvarttagcs of a multiple balloon cmbodiunc:nt of the c,atheter 10 is that ihc: flc?:t' and temperature of the heat exchange 1lttid 85 ean be more easily controlled aiong the entir:; length of the heat exctiartge region 47.
Realizing tnat the heat cxchange fluid 85 will be caoles t prior to ctitering into a heat cxchangc ~vitli the blood 'a 1, and warmest after ihat lteat exc,hangc, one can advantag,cously control not only thc vClocity and vol.unic of flotiv, but ctlso tl?e direction of flow within each discrcte balloons 56, 58 and 61. Another advantagge of a multiple balloon design is the ability of thc catheter to bend and slex when ptae4d in a curved vascul.ature.
Sijielc balloon desigas would be rigid, stiff and irufletible by comparison.
In order to facilhate the maximum heat exchztiue bctl.vzen the fluid 8= and the blood, it is dnsirable to fsrovidt a balanc::d flow of ti-ke hcat cxchange. f3uid 85 aloa8 the zntire le~,oth or the heat c:xchange ragion 47. In thc enibodiment iilustratcd in Fioure a, cfFicicnt heat traLrtsfer is facilit.atcd by countercurrent flow wherc the heat exc.hangc fluid85 is di:ected to >=low cott1ltcr to the flow of the blood 31. To that end, the inlet holes 70, 72) and 74 are positioned distally of the outlet holes 76, 78 and 81, respeelively. As the blood. -3, 1 ftovvs disially along the outer surt:acc of the catheter 10, this rclative position of thc inlet holes and outlr.t holes cattses the hcat exchatzpe fluid tct ftotv iti t:te opposite d;yection, proximally in eacla of the ba.lloons 56, 58 and 61.

Thu arxiount. of flow within clch of the balloons 56, 58 and G 1 can also be cnn!rollcd by the size of thc inlet hol:.s 70, 72, 74 and o.nlet holes 76, 78 and 81. In a prcf<.rr=:ci etnbodimcnt, this flow control is provided solelv by the inlet i=ioles 70, 72 anei 74; thc outlet holes 76, 78 and 81 arE sized hu-ger thari their respective inlct holes so that they offer little resistance to flow. In this err,hoclirncnt, the lillet ljnlcs 70, 72 and 74 are sized to be progres5ivzly snialler from tlu distal ;:nd 45 to the proxicnal end 43. Thtts the hole 70 is largc:r thrui the hole 7?_ whicl-i is larger than the tlole 14. As a result, rhe resistaa,ce tci the flow of heat cxeJtlne,e fluid 85 in the most distal balloon 56 is less than that in the most proximal balloon 61. This ensuxes that the coolest heat cxchange fluid 85 is sliarcd equally among all of the balloons 56, 58 AMENDED SHEET

~ CA 02340237 2001-02-12 ~tlnted, .,, ::::. . .: _. ... . .... . ...
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and 61 rcgarcilcss of t:ieir rositior. along the shaft 40. In ati embodiment wherein the flaw is cozttro3le.d by the outlet holes 76. 78 and 81, these holes can also be providcd with a relatively reduced size from the dislal end 45 to the proY.imal en143.
With any of thcsc structures, a more balanced flow uf thr heat exchas~~e fluid ca,i be achieved iri order to facilitate the hibnrst clegree of heat exchangc along the entire heat cxchange region 47. Altcrnatively, the flow of hcat excl,anac fluid can also bc b:.lanced by providing thc. hoies 76, 78 and 81 with non-circular configurations. For cxamplc, these lioles inay be foniicd as longitudinal slits extending axially of the cat,hetcr.
A further embodiment of the invontiUn is iliustrated in Figure 7 wherein a sinL3e shcet of ma:erial 101 is used to fornt seliarate and clisLinct itidiv'idual ballo,--ns, twooi whicl? are dc5ignatcd by the refcrence nutuerals 103 and 105. As opposed to the racSial balloons 56, 58 and 61 ofthc previous embodiment, the balloons 103 and extend axiaLl;= along the surface of the shaft 40. ror example, thz balloons 103 and 105 form individual ball_oor, cavities 107 artd 110, respectively, which extend froin a distal end 112 to a proximal end 114.
'T'liis embodiment of the catlieter containing the axial balloo.tts 103 and tiiay includc: a sha[i 40 with a sligllt.l;= dificrcnt configuration. As best illustrated in Figurc 9, the shaft 40 may includc an outer tube 121 having an outex surface to which the sheet material 101 is attached and withiit which is disposed a Llistal sealing plug 123. An inner tube 125, which can be disposed coaxially with the outcr =
tube 121, has an inncr lu:Y en 127 and dePines with the outer tLbe 121 aii otiter lurncn 1?0. A pair of inlct holes 132 and 134 provide flow fluid communication betwccn the ituier lumen 127 and the balloon cavities 107 and 1 l 0, rc:spc:ctively.
Sisnilarly, a pair of outlet holes 136 and 138 provide fTuid co>>>n;unication between the balloon i;avities 107 and 1 10 and the outer lumen 130, respectively.lln inncr plug disposed between thc inner tube i25 and outcr tube 121 to seal the outer lumen AMENDED SHEET

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-i5-betvveen the inlct holes 132, 134 aild c,utlct holes 136, 138. For the rca.5ons previously i7otcd, a preferred embodinnexat has inlet holes 132, 134 which arc disposed distally of and siv.cd small-.i than the outlet holes 136, 138, respectively.
This orientation will provide countercurrent flow in a catiieter 10 wli ich is ;.nsertcd downstream into ati artery such as the caroLic? artery 23.
Embodinients tiiNcli are intended to maxitnize hcat transfer will take advantage of the fact that heat xcl1ange is enhunced wheii either, or both, the body P~uicl or tlsc heat exchangc i7uid is provided with well mixed flow. Mixing can be enha.3ced by 1-.Yroviciing irrcgu:ar surfaces next to which either of these fluids 1'-o1y, For cxan3l,fC, with rcference to Figurc 4, it will be noted that a spring 150 can be dispoicd around the shaft 40 insidc each of the balloons, such as the balloon 61. In this embodiment, tie spring 150 tipsets the laminar flowr ofthe heat exclz angc {luicl 95 thercbL producing the desired mixint~ of this rluid. 7thcr structures can be positioned within the c=lvities fornted by thc; hailoons 56, 58 alYd 61.
Mixing can also'oe enhanced within the body fluid which flows along tlte outer surface of the cathcter 10. In this case, the multiple radiat &,lloon embodiment illustrated in lrigurc 4 is of advantage as ca.ch of the balloons 56, 5R and represents a peak and defines vvith 7he adjacent balioon a va:lc:y along whicit thc blood 31 flows. This series of peaks and vallc:ys also ttpsets thc laminar flow of the bcidy f1LEiu. tviixirig of the brydv (luici can also be enhanccd by providing otljcr structures asong the oiiter surfacc of the sheet n;ateriai 62. 64 and 66 which forrn the ballouns as well as any exposcd arcas of the shaft 40 in the heat exchange rcgie-n 47.
By way of exarnple, a rnultipl:'city of granules 145 can be adhered to tlic outer surface of tho radial balloons 56, 58 and 61 or the axia; balloons 103 and 105 as illustrated in Figure 9. Ridges can also be provided along tliese surfaces.
With some body fluids, it may be desirable to inhibit turbulent tlow and facilitatc larninar fYow. This may bi:. trnte for exaia ipic in lhe case of blood where undesirable hemlysis may occur in response to incrceiscd turbulencc. Such an ernboclirnent might be Particul<<rly desiu=alile for use ith radiul balloons where an AMENDED. SHEET

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09-42;~QÃ7fl outcr balloon 152 woulcl prorrwte lanlinar flow by rcducing the height differential bctwccn the pezl<s and valleys dcrnccl by the baflooiis 5G, 58 and 61. This outer balloon 152 is best illustrated in k'igure 10. To further promote laminar flow, thc outer sttrface of any strueture in the heat exchangc region 47 can be provided with a coatina 154, such as a hydrophilic or a hydrophobic coating to t-aodify the boundary layer . Thus the outcr surface o F the shaft 40 as well as the outer yurCacc of any of the balloons SG, 58, 61, 103, 105 and I S? catl be protiided with thc: c;oating 154. Tlze coating 154 may also iticlude other ingrLdicnts providing the catheter 10 with additional advantagcous properties. For exa.nlple, the coating 154 may include an 0 antithrotr.bogenic ittgredient such as hcparin or aspirin. Such a coating 154 would not only inhibit platclct dcposition but also the formation oCblood clots.
As prc;viously noted, the charactcristics or the heat excliange iluid 85 may :tlso be of irnportance in a particular heat cxchange environmEnt_ Althc,uch the heat cxchanue fluid 85 may inclutle various liquids, it i5 bcficvccl thut gases may prvvide IS thc gre.ltcst tettiperature ditfcrcntial with the bodv fluid, Particularly if this fluid includcs blood, gases that arc inert or othct'vvise comF3tibie with the vascular syrstern will be appreciated. Although several inert gases might fulfill thcse requirements, carbon dioxide is used for the heat exch3nge rluid 85 in a prefen-ed c-rnbocliment of the invention.
20 A further eriiuoditnent of the cathc tcr 10 is cotttemplatcd for maximizing the stuface area availablc for ceat cxchange. A,s illustratcd in Figures tOR, and IOB, the catheter 10 can hc Formcd with a distal end 45 of the shaft 40 disposed in the natural :.ontiguration of a spiral or pigtail 172, '.Clic rclatively large diar.ictcr of the pigtail 172 facilitatcs heat cxchange, but tends to dctcr from a low profile desire for 25 insertion. Undcr these circumstances, it may be advanta-eous to insert the catheter ovcr a stylet or fiuidextire 174 in order to straighten the pigtail 172 as i llustratcd in Figttrz 103.
hlvperthermia and hypothertnia for sclcctive regions of the b<xiy can also be achieved by placing ir, the body coitduit, such as thc carotid artery 25, a heat pipe AMENDED SHEET

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_1 7_ 161 be5t illustrated in the schematic view of Figure 11. In this etaibodinicnt, the heat pipe 161 in.cludcs a distal end 163 and proximal end 165. The distal end 163 is adaptcd to be placed within the body conduit, suwh as the carotid artery 25.
'fhe protimal end :65 of the heat pipe 161 is adapted to be connected to an external hcat sink or cooler, such as a thermoelectric couler 167 or water jackct 168. A
wick structure 170 is provided in the lieat pipe 161 to facil itatc a P:ow of heat exchaz~ge fluid itcim the cooler 167 to the distal end 163.
ln a process inm-olving the hcat nipc 161, illustrated in >=igt.re 12, the hcat exchange fluid is moved from tiic proximal end 165 of the hc3t pipe 151 either by gravity or by e=apillary action of the ~vick structure 170 to the distal end 163. At thc distal end 163 of the heat pipe 161, heat is trans;er:ed from lhc body fluid, stich as blood, to thc heat exchai~ge fluid in its liquid state. This heat exchangc liquid absorbs a heat of vaporization a., it passes into a vapor state in thc hcat pipe 161. The heat exchangc fluid in its vapor state creates a pressure gradient between the ends 163 and 165 of the heat pipe 161. "i'his pressure gradient causes the vapor to flowto the cooicr 165 where it is condensed giving up its latent hcit oi t=aPc:ri7ation. Thc heat etclartge fluid in its liquid state thcri passes back through thc hcat pipe 161 through the wick structun 170 or by gravity. The passive hcat exchange system provided by thc heat pipe 161 is v<u.tfunrtight and can be operated with a z.>;ni-mum amount of the heat zxc;ian'e :1uid.
Although the heat cxchangc catheter 10 will be advantageoiis in the hype.~rtliormic or hypothermic tr.-atment of any portion of t"e body 12, it is believed that it will be particularly appreciated in those proccdures which can bctiefit from the hypothermic treatment of the brain 19, such as the tre.atment of ischent.ic strokc andlor 17cac,1 trauma. As pre-4ously notecl in comments dircctcd to Figure 1.
tlac catheter 10 ean be inserted intci thc fcrnoral artery in the groin 14 and directed ?hruugh the aottic arch 23 into the cominon carotid 3rtery 25. As iliustrated in Figure 13, tlle cathctcr 10 can then be movcd into the region of the artcrial branch 27 where it tivill cnca>untcr the external carotid artcry 30 and the internal carotid artery 32.
AMENDED SHEET
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179-02~2~ 1r3ESCPAM l7 Siitce the external carotid artery 30 i:a directed primarily to the facial region.s, it does not supply a si8ni Ccant amount of blood to the brain 1 S. Tn contn,3st, the iiitcrnal carotid artcry 32 is alinost solel}r responsiblc for fceelind the cap'tllary lMd of the lirain 18. 13ar,e.ct on these considerations, hyrotlzcn-nic trc:atment of the brain 18 is best addressed by coo[ing the blood in the internal carotid artery 32 without wasting any of the cooling properties on the external carotid artery 30, Jn :~ method associated Nuith one embodiment of the invention, the most distal of the ballooris, such as the'oallooty 56 in Figure 13 is preferably positioncd witbin tiie internal carotid artery 32. The more proximal balloons 58 and 61 can be disposecl along the conunon carotid actery 25. This crnbodimcnt of -he catheter 10 and its associatcd n,cthod will Lzchicvc Z higher dcgree of lacat transfer within tho internal artery 32 than the eAternal artery 30.
sn anothcr cmbodiment of the catheter 10 best illustrated in Figure 14, an occlusion balloor-175 is provided distally of the heat exch-.ui;e rcgion 47.
In tlzis erribodimcttt, the occlusion balloon 175 will pre,ferably be int]atable tlirough a separatc lumcr_ i.n the shafft 40. As the catizctcr 10, approachs:s the carotid brancli 27, th:, oL'cjUs1(3n balloon 8 i is directed into the external carotid artery 30 and inf7ated in order to at. lcast partially occl~sde tttat artery. The rcmaining proximal balloons 56, 58 and 61 in the heat exchange region 47 are left within the common carotid artery 215 to proIriote heat exchangewrith the blood flowing to the branch 27. '%Vith the external artery 30 at least partially occluded, heat transfer occurs prirnarily witll the blood lYoNvini; into the iutecnal carotid arr.cry 32.
A further emliodi mcnt of the invcntion is illu5tratcd in Figure 15 operativelv disposed in the comr.ion carolid artery 25 and internal carotid artery 32. In this case, thc catheter 10 includes a bal loon 181 which is attached to th; distal end of the shaft 40 ancl provided with a spiral configuration. More speciticaliy, the balloon 131 may bc formed from several individual balloons, as wilh the enibodintent of figure 7, for as individual flutes 183 on the sint;le balloon 18 1. In cither case, the separdtc:
balloons (such as the ballovns 103, 105 of Figiire 7) or the flutcs 183 are oriented in ~ENOED SHEET

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a spirai confil;uration around the axis 41 of the c3theter 10. The shaft 40 cast be p.rovided with any of thc conPigttrations previously di5:.ussed such ras thc ccccntric crynfigtiration o_' Figure 6.
By providing the bailoon 181 with a spiral confisuratott, Itcat exchange is cnh3nced by at least two of the factors previously discussed. Notably, tlie surface area of contact is increased between the blood 31 llowin8 externally of the balloon 181 and the hcut cxchan8e fluid flowinb internally of the balloon 181. The spiral configuration also enllances the mixing properties of botlt the blood 31 and the hcat exchailbe fluid 85.
As noted, the hcat exchange fluid 85 u:ay be coolcd to a sub-zero temperature . In order to the;rmaliy protect the int:.'rnal lining of the artery 32 from dircct contact with the sub-zcro eool nt, it may be desirable to provide the tips of the flutes 183 with a thicker wall 185, 3s show=n in Figure 16.. This thicker u-all 185 might be advaiitagcous in any of the balloon. contiguraticns prcviously discussed, but would appear to be xiiost advantagccLs in the embodiitieaz*.s of Figure 7 and 15 -Mhere the contact with the artery 32 tcnds to be inore locali:.cd by :hc loneitudinal balloc>ns 103, 105 (Fisure 7) on the spiral flutes 183 (I'ieurc 15).
Still a furthor embodimcnt ofthc invention is illustrated in Figure 17, In ihis embodiment, the shaft 40 includes an iilner tube 190 ciisposed within an outer tube 192. These tubes 190, 192 may be concentric and lottgituditiflly tnovablc relative to each other. The tubes 190, 192 krminalc respectively in iZiani#'olc;; 194.
196.
Bctweeilthese nianifolds 194, 196, a niultiplicity ofbollow fibers 198 can be disposed at thc distal cnd 45 to define tlte heat exchange region 47 of the catheter 10.
Thc l,nitaw fibers 198 cach incliido an intcrnal lumen which provides fluid coinmunication betwccn the manifolds 194 and 196. In operation, the heat exchange fluid 85 tlows distally along thc inner tube 190 into thc distal manifold 194.
From this manifold 194, the hcat exchange lluid 85 flows into the internal Itimeiis of the hollow fibers 198 proYinaally to the proxiitial nlanifold 196.1'hc warrner heat AMENDED SHEET

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~. ~~ . ~--- -- -- nfi9- Oq~i._T.G:RC'7 c'c> ~,-1:3r=sGPANfG1 -2e-exchange tluid 85 ilnlvs proximally froin the tt-anifold 196 betwcen ihe inner tube 1 90 EuzLl outer nibe 192.
l'rcfcrahly, the hollow fibcrs 198 have a wall thickncss that is thin onougn to allow maximum hcat transfcr, yct strong enough to wifl2stand the pressure rcquirc:mcnts of the heat exchange fluid 85. The hollow fibers 198 are fitrtlier adapted to ac1Leve ideal heat transfer by the maximization of botli surf acc arca ans1 coolant flow. The snlaller the diamctcr of the fibers 19$, the more fibcrs can bc fit into the cathc:tcr 10 with a correspontliag increase ii, surface arca. As the dianieter of the libers 198 is decreascd, however, the resistancc to fluid flow increaGes thu.-lowering thc ooolant flow rate. The effzct of the inflow and out.a'low lutnens must also be considered in detcrmining the 17uic1 r:sistance. Ideally, the wall thickness of the hollow f'ibers 198 is in a range be*,cvccii.00025 inches and .003 inches.
In a preierred embodimettt the wall tliick-taess is in a ranic betWc;en.-}0075 ii?ches and .002 inches, and ideally .00125 i11ncCs. 'l'hc Uutcr dianzeter of the boilow fibers 198 1S .vitl typicatly be between.008 inch:s aild ,035 inches. in a preferrcd emboditlietlt the outer diatnetcr is in a range bctween .010 inches and .018 inches. and icteally A15 inchcs, It will be noted that the kteat exchange fluid 85 flowing in the inner tubc is insulatcd in severa( respects frorn the blood streana outside thc c4thclcr 10. This flow channel in thc inncr tube 190 is insulated not only by the wall of the outcr tube 192, but also by the coolant returning in the flow chartrlel associated with the outer tube t92. "Thc heat exchange fluid 85 in the inncr tubc is further insulated by the thickncss of the inner tube wa11. LZ the heat cxchang4 region 47, the wall thic:knesses associated with the inner tube 190 and thc outer t;ifoe 192 is preferatuly red.Icecl in order to providc additional volume for tho hollow fibers 198. With a reducec3 wall thiekness, the inner tube 190 also contributes to t:te heat exchanDe occurrinP
in the regioti 47.
The hol Icw fibcrs 198 offer se vctal advantages to this enlbodiment of the cathctcr 10. Notably, they provide a vM hieh surface area between the blood 31 and AMrNDED SHEE;

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the hcat tixchange fluid 8i. This greatly enhances the heat exchan5e cha-actcT2ytiCs of this embodiTn; nt_ Countcrcarrcnt flow can also bc maintained further facilitatitag the heat exchatige capabilities of this catheter.
't'hc hollow fibcrs 198 can be spiralcd as illustrated iii Figure 18 by twistir.g tlie inner tube 190 with respect to the outer tube 192. This charactCTistic c:in be used to provide a shorLer and lower prolile heat exchange recion 47 in ordcr to facilitate introduction of ttte catheter 10. A low;r profile niay also be obtained by separating thc inaniiolds 194 anti 196 a distance substantial?y equal to the length o('thc ibcrs 198. This will tcnd to hold thc fibcrs in a sLraight. pdrrtllcl relationship and thereby facilitate introduction of the catheter 10. The spiraled con5guration ofthc iioliow fibcrs 198 can bc maintained during heat exchange in order to further increase tha heat exchange area per unit lenoth of thc catheter 10, .~Iternativ~el~~, ihe fibers 198 caii be positioned to liiosely flo:it and undulate between the manifolds 194 and 196 ics illustrated in Figure 19.'1'his c}taractei:stic of the fibers i98 will i;ot only provide 13 tlte increased heat excliaii-e area desircl, but also promote mixing within the blood 31.
The fibers 198 will typicallv bc fortncd of conunon materials such as polvolcCn nylon and polyurethane. The fibers can be coated with a clQt-inhibiting.
material such as heparirt. Other matcrials advatttageous for inhibiting the !'ormation of blood clots mught include those which forrr, polymer surfacc:s with 16 or carbon <11ky1 chains. Thc:c matcrials attract llbtimin c-nd thereby inhivit c.ot Cormation. In a further esnbodinient, the fibers 198 cmi bc provided with micropores which pcnnit the leaching of such clot inhibiting pharmaceuticals as heparinized saline which could also scrvc as the hcat cxchange fluid 85.
The embodiment of Fi-urc 20 also takes advantage of the significant heat exchange characteristics as5ociated with the hollow fibers 198. In this embodiment, the manifolcl 194 at the distal end 45 of the eatheter 10 includes a pottinc scd1201 with a distal surface 203. The fibcrs 198 aTe hcld in th:: potting sctd 201 with the lumens ofthe fibers 198 expoycd at the surfacc 203. The distal end o~the innet= tube g4Ei~;;,Et~ SHEET
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084DESOF~AM-D

190 is also held in the potting seal 201 with its lumen exposed at the distal nurface 203. In this embodiment, the manifold 194 includes 3 cap 205 which may have a hcmisphc.re canfiguration. This cap extetids over the distal surfa-ze 203 c:f the puuing scal 201 and provides fluid comntunication bettvccrt thc lum.cri of t.he uuier tube 190 and the luniens of the ball~)w libcrs 198. '1'his cap 205 may also be constructcd of matcrials amcl wdll t1lic.kn4sses t.hcit insttl<Zte the blood vesscls frnni potcntial contact wittt a cold catllctcr tip.
Figurc 21 illustrates in a cross-sectional view a first flow chatmcl 204 wll9ch extends along the lumen of the inner tube 190 and a second ilow channel L06 which extends along the luincn of the outer tube 192 outwardly of the inner tube 190. As tEie heat .xchange fluic185 is introduced into thz ftrst ftow chanijel 204, its dircction is reversed in cap 205 so that the flow crf thc fluid 85 in tlic 5ol,'otiv fibers is counter to the flow of the body fluid, such as blood, iz1 thc body co duit, such as the artery 32, Ahcr moving through t?ic fibers 198, the hcat exchanbe fluid 8: passes along the second flow channel 206 between the inner tube 190 and outer tube 192, atld exits the catheter 10 at the proximal end 43.
'('he embodirnent of Fibure 20 also includes a Y-connector 207 disposed at the proxiinal end 43 of the catheter 1(}. This eanncetor 207 is shU,"'n in greater detail in ttic cnlar6cxl vicw of f'igurc 22. In ihis view it can be seen tliat the conktcetor 207 includcs a body 21 U with screw threads 212 at its distal end and scrcw thrcads 214 at its proximal end, At the dislal end of the body 210, a screw cap 216 mates with the screw threads 212 to engage an annular flangc 21$ at the proximal end of the outer tube 192. In ihis manncr, the Y-connector 207 fortns a seal with the l,roxiinal end of the outer tube l92 ancl provides fluid communication between the sccnnd flow channr.:l 206 and a lumen 221 of the Yconncctc,r 207. A side port 223 coirununicatc, with this lruneri 221 and provides an cxit port for the secondary flow channel 206.
In order to prevent leakage from the lumen 221 at tlie proximal cnd 43 of the Yc.c,nncctor 207, a releasable scaI 225 can bc formed at the proximal en;i of thc body 210. In the illustrated embodimcnt, the releasable seal 225 includes a cap 227 wliich U Si=iE_ ET

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.... .. ...... .
~n rrr i nnx-~-~nnrn nu rrrr i ~rwn~An ~rrõ~., ...,,., , --trc=~t = eo:,s.acc - _ ., ~ - - - - - -~~ 8~~~.~i -1JS991#~4~~ >ESOPAt~I l~

is thrcaccd to rcgister with the threads 214 of the bocly 210. This cap 227 extends around the p.rc-xirnal enfl of the body 210 and co,-npresscs an clastomeric washcr 230 agait!.st the body 21 {'i and thc outer surface of the inncr tube 190.13y tightciiing tl'.c cap 227, the washer 230 is compressed to seal the lumen 221. This compression also fttnctions to inhibit, but not ncccssarily prevent, axial movement belween the outer Lube 192 and inner oLfbe 190. The relaasabilily of the seal 225 can be appreciated in orcicr to facilitate this relative movernLnt between the tubes 190 atid 192 for tl;ae rcaGons Prcviously discussed. This foi-rn of a rclca.5ablc. scal 225 is commonly referred to as a Tuohy-Borst seal, Thc rclativc movcmcnt bctwccn the inncr and outer tubes 190 and 192, respectively, will be appreciated in order to provide the tubes 190 and 192 with a first position wherein the fibers 198 have a low profile configuratian as iFlustraled in Figure 23. The relative mcvement will also be appriciatcd in order to provicle the tttbes 190 and 192 witli a second position wIicrcin the hollow tibcrs 198 forni an increased profile as illustrated in Figure 24. lt c"an be appreciated that this profile will facilitate heat exchange by providing an incxeased spacing of the individual hollow fibers in the body f.uid.
Ar,other feature associated with these two positions is illustrated in Pigure wliere the inner tube 190 is expanded in thickness at its distal end in cardcr to furm a ranip or tapcr 232 ln this crnbodimcnt, lhc taper 232 is annu;a.r zind extends raclially outward with progressive distr.l positions alon; the tube 190. As the inncr tube 190 is drawn proximally relative to the outer tubc 192, the tapcr 232 is brought into sealing engagement with the proximal end of the hollow fibers 198 and potting seal 201, This effectively seals the distal end of the outcr tube 192 against the outer surfacc of inner tubc 190, and prohibits any loss of the heat exchange fluid beiween the inner and outer tubes 190 and 192 at the distal end 45.
This loss of the heat exchange fluid 85 can also hc addressed with a seal tube 234 which catt be positionzd betwecn the inncr ancl outcr tubes 190, 192 and intivardl}= of tlic hollow fibeTs 198. In this cntbod'sment, a distal end 236 of the seal AMENDED SHEET

.........................
-rn : .r r nni~-r~nnrn .nu irn r tr ttn~~r+ ~rnrr.rt ~crvnn ,r ~r.. ... . - ---- -~.~. : -...-...,....
~F'.~ : ~.'~-I.T-L;RL'=7 Ro a s_ 991~18635.6 1.1399108455 DESGPAMD-Ã~~=Ã32-2fl00.;

tubc 234 is bcnerally coextensive with the d'-stal end of the outer tube 192.
Thc scttl tubc 234 is prcnfcrably provideil with an irutcr dianieter Sreater thatl the outer dianictcr of the inncr Lubc 190. As a result, the inner iuhc; 190 is fr; c to niove rel:ttive to the outer tubo 192 to achieve the advantages prcviousty discussed, Hozvcvcr, when the i:lnc :~ tube 190 is drawn sufficiently proximal of the outer tube 192, the taper 232 will contact the distal end 236 of the scal tube 234. This effectively :'or:ns t.ie seal between the inne;= and outer tubes 190 and 192, respectively at the distal end of the outer Lubc 192. Vdilh :hc taper 232 wL.tlged against the seal tttbe 234. the fibers 198 are maintained in their operative ti-cc-1Q floating configuration as illustratcd in Figure 24.

Alternatively, a non-Lapered inner tube 190, can be mated -v,-ith a closely fitted seal tube 234.1~~r~ith very smail a.r,d controlled differences between the outside diameter of the inner tube 190 and the inside d'tameter of the scal tube 234, for example 0.0005 to 0.003 inches, :tn effective seal can he constructcd with.ouL
thu tupcr 232. This ctnbocliment relies on thc lericth of the seal tttbe 234, the surface tension of the coo!attt fluid 85, and the sntall capillary gap to create a resistartec greater than thc pressure of tho 4ooiant fluid during operation. This design does not rcquirc the inncr tube to be moved a.fi'ed distance relative to the outer tube and does not require a censtant tensioii betu~ccu the inner and outer tubes to effect a seal.
The se-al tube 234 is prel'erably constrttctcd oPpolyitnide tivbich allows for a prc:cision ancl constant inner diameter. In addition, polyiitlidc is avaiiah?c in vcry thin w=ail th.icl:.nessos so that the scal tulnc 234 will not occupy a significant portion of tbe aniiulax space which is morc appropriatcly dcdicated to the fibers 198.
A method for manufacturing the hollow fiber embodiments of the cathetcr 10 is illustrated in Figurcs 25-27. ln kigtz:e 25, a planar mat 241 of the hollow ftbers 198 is formed with a general,y pl.mar configuration. In this mat 241, the fibers 198 are orietitcd in a getieraliy parallel configuratiun with angled potting seals 201 and 243 formed at opposite cnd,ti of the fihc;rs 198. This fiber mat 241 can bc rolled onto the outer surfaccti of Lhc inncr tubc 190 and seal tube 234 as iliustrated in ),'igurc 26.
WENDED .SHEET

*CA 02340237 2001-02-12 l~t=I~lt~4~ _ ;..;::::
-::::. :::.:--...::::.:_ .................._......
~n ~rn r nn~~~~nn~n nir trr t 'P1Vr -M~r -rrrrnn nn~;nn r: r . ~. ~ ~~ = ~--- -Sf;# : ~:9j ~ r;r=;F'. . .:sz a t., ~rni-=-- .

~AG?
Ã?9~t}2~2fl~fl i In this stcp, the Fotting se:il 201 is fornned around the clistal end of lhe inner tube 190 whilc the potting sc:al 243 is forined around the r.iistai end of the scal tube 234.

By initially forming the fibers 198 ir,to the mat 241, a generally uniforrn t'iickness of the mat 241 can be maintained, Rolling the mat 241 onto the tubcs 190 ancl 234 tttaintains this unifarm thickness a.nd also facilitates orientation of the tibeis 198 onto the cylindrical tubes 190 and 234. This techniyue also forms ari inwairdly spiraling helical bond joint prol'iic that a.icls in cli%x.tina tlte blood flow in order to inhibit clot forination by preventi:ig stagnarit blood flow areas at the bond joint.
Witli ttic potting seals 201 aiid 243 suitably bondcd to the tubcs 190 and 234, respccti;=cly, the cap 205 can be stiountcd over thc distal end of the fibers 198 as previously discusscd. At thc proximal end of the fibers 198, thc scat tube 234 can be tnoutited in the distal end of the nuter tube 192 as illustrated in Figure 27, The seal tube 234 offers some interesting possibilities for the infusion of fluids at thc distal end 45 of lhc cathctc:r 10. Of courst, it is always possible to provide an additional lunien witltin the shaft of the catheter 10. in sucli a;l cnibodinicn:, the lluid to bc intitscd could hc injected into the additionzi iumcn at the proxirr.al end 43 to exit the catheter at the distai end 45.
Altern,ativ;;ly, the fluicl to be infused rnight be included in the heat exchange fluid 85. The tolerance br:twccit the seal tube 234 and the outer diarneter of the iru-icr tube 190 could then be controllud to provide a calibrated leak of the heat exchange fluid 85 at the distal cnd 45 of the catheter 10. Micro laoles nti ght aiso be dri l lcd i;,to thc outcr tube 192 or inncr tube 190 to providc for ri controllal leakage of thc infusion fluid.
Each of the forcgoing embodiments of the heat exChange cathctcr 10 is adap;ed for use in cooling the entire human body, or perhaps only a portion of the to.al body. Methods of operation will vary widely depending on the focus of a pa-ticular procedtu=e. By way of exaniple, it will be noted with reCerence to Figure 28 that the catheter 10 is patrticulat=ly adapted for cooiing blood in a procedure which may invol-vc as mEiny as three of tlie catheters 10. In Figurc 28, a liuman body 245 is AMENDED SHEET

~r, ~nn i nn~ ~~~nnnn a~,~ crt ~r~nn-un nirrnn rnnrnn cr r nr= n-n r~~~- ~~. --=
;W, 4 G;R F: ~< C as --nr,r.

DESCPAMD

2.G-illustratc;d alonE with a poriion of the blood circulatory systcm inclucling a pair of fcmoral veins 247, 250 tutd a subc4avian vein 252. Thcsc veins 247, 250 and 252 all exte:nd into the vena cava 254 of the body 245. In this procedure, separate catheters, such as Lhe Iteat exchange catheter 10, can be introduced into each oFthe fernoral veins 247, 250 and the subclavian vein 252 with their respective heat exchakqe re-ions disposed ia the veiia cava 254. Alternatively, :uid preferably, only two such cathctcrs would bc ir.trcxiucc;cl from twc) of the thrcc vcins 247,250 and 252.
A systcmic velsion o~tlie catheter might have a diameter in a ran~e of bctNvecn 9 and 15 1'rcnch, and a lcngth of approximately 20 to 80 ccrttirnctcrs long.
It is contemplated that this design cottld conceivably cool the body in several houts.
'['hc usc of two such catheters inserted into the vena cava 254 as mentioned above could bc expected to reduce the tirtie required to cool the body by a factor of 2. It will bc apprcciatcd tiiat similar catheters and methods can be used to lower the tctnpcrature of blood in the natir=e carotid or in the vertebral circulatory systern. The amount of blood heat lost is'dircctly proportional to thc tempcrature dif','crcntial, the blood velocitv and tltc blood-to-cathctcr suriacc area.
Particularly in an operative setting wherein the heat exchange catheter 10 is to be inserteci into a blood vessel, a further desibn feature best illustrated it, Figures 29-33 will be ofparticular interest. In these views, an introducer 256 is positioneci for pc.rcutancous insc:rtion into a blood vcs.,cl such a5 the fcmorril vein 250. A sleeve 258 is provided on the cathetcr 10 i-tnd slidablc along the outcr tube 192 between two positioitg. Thc first position is illustratcd in Figure 29 wherein the sleeve 258 is disposed in a spaced relationship with the heat exr.hange region 47. The second pos:tion of the sleeve 258 is illustrated in Figure 30 ,Acrc the slccte 258 covers the hf,:st exchange region 47. Tn this position the balloons or fibers associated w=itlt the region 47 an; cornpressed to a low profile state greatly facilitatit3,o, iittrodLction c}Fthc c<<thcter 10 into the introducer 256. In addition, the covered heat exchange rccion 47 is stiffcncil for easier introduction itito the introducer'256. Thc fibcrs aadior balloons are also protected from the interior surface of thc introduccr 256.
Uptionally, a AMENDED SHEET

:: :::.~ :::::..::: :..: ::..............................
i!r nns,-7-77rnrrn vuu vrr r ~r~~rn-Mrr -rirrrr.r. ntrunn !i I
rr. n ~ ~~~~ ~~ ~~ =
Lf:H :~~a~=~~ ~~ . r.Q a~~ _~~~--- .,,. -Ã}9-Q~~~Ã1470 99948685:6 - U~9W0845&: DESCPAMD -27-stillcninb mandril may bc inycrtcd down one or more of thc tubes 190, 192 to facilitate introduction of the catheter 10 into the introducer 256. After tliis initial insertion, the sleeve 258 remains within the introducer 256 while the rcmainc',cr of the hcat exchange region 47 is moved dislally into the conduit as i1lu;,tratcd in Figure 31. At this point, the sleeve 25 8 can be removed from the introducer 256 by slidinc it proximally to its first positien as ilhtswated in Figure 33.
This method of introduction is facilitated by providing the Sleeve 259 tivith a gcncrally cylindrical conriguration. The diameter of the cylincl:ical sheath should bc less that tLc insidc diameter of the inlrndt;ccr 256. Howcvcr, at the proxintal cnd of ? 0 the sheath 258, an annttlar flange 261 or other enlargeraent ca.n be provided to ensure that the shcalh 258 does not pass beyond the introducer 256.
Another featUre associated with the present imveniion relates ttr a blood clot basket or snare 263, best illustrated in Figures 34 and 35. This stiare 263 is prcfcrab1y positioncd downstrcani of thc hcrat cxchangc rcgion 47 associatcd with the cathcter 10, It being appreciated that atiy structure disposed in a blood vessel may tcnd to gencratc blood clots, it is the purpose of thc snare 263 to capture any such clots. The snare 263 of the preferred embodiment includes a plurality of wires 165 whicll extend along a shaft267 with their opposing ends fixed i:.t the manifold 194 and a distal cap 270. The wires 265 in a preferrccl embodicnc:nt are formed of staiiiless steel or a nickel titanium alloy.
In the illustralc:d ccnt,odiniCnt, the shaft 267 exlcr.ds to the proximal cnd of the cathctcr :0 eithcr through the lumen of the inner tube 190 or altert2at~veIy througin a second, separate lumen in the inner ittbe 190. In the former case, a sea3 would be reqttired at the distal end of the manifold 194 to prevent any Ieakas-c of heat exchange fiuid 85 around the shaft 267.
In either case, the shaft 267 is free to move relative to the concentric tubes 190 and 192. Whcn the shaft 267 is tnoved relatively distally, tlie sxiare wires 265 arc: provided with a generally low profile. When the shaft 267 is movcd re;latively ~,N'thtJD~-% ~~~=tt :.: &CA023402372001-02-12 ::: :.:::. ::. :::::. ::.....:..........................
~n inr r nns~~-~nn~n Incr vri i ;r~-n-run ntttrnr- n-nmrt ir "r. i n 7n r nnn nn nn t 1rJ~~9~Q8~~~ i~iM~GPAA11{~
Ã~J-~}2-ZQ!<l~:>

proxi-nally, the wires 265 deF loy to provide the snare w-ith an en<<,rged ) igh-proCle coniiguratian as illustratcd in Figure 3 5.
In a further etnbc,ditncnt of ttte s:sal-e 263, the wires 265 arc connected ic) ilic tnanifald 194 and extend to distal ends which arc unattachc.d or frcc. 7"hc wires 265 in this cmbodiment, best illustrated in Figure 36, are bent to a deployed et?largcd cortCgtiration. With such an embudiment, ins:rtion is facilitazed by prov;ding a :lelivety slteath !uhich is tnovablc to maintain the wires 265 iil a low-proti{e state.
Once the catheter 10 is in place, the sheath 262 can be rzmoved tLcrcby permitting the wires 265 to aettornaticaliy expand to tlicir cnlargcd high-profile state.
With respect to the forgoing disclosure as a whole, it will be apparent that mttnv variations from these prcforrcct cmbUdimcnts will now bc apparent to thosc skillcd in the art. For cxamp?e, vvith respect to the balloon embodiments previously discusscd, it will be appreciated that the advantages of this invention caai be dcrived with orily a single balloon. On the other hand, there sccm to be scvc:ral ac3vanlagcs ] 5 assOciatcd with multiPlc ba6loott ciiilindi nients. Notably, a tnore even and b:tlauced transfer of heat exchange can be acliieved with rnultipie balloons. In addition, there appears to bc better mixing with respect to both the blood 3 1 a., well as the heat exchange fluid 85. Multiple balloons also provide an increased strrface area relative to single balloon embod'unents. I'urthct=inore, the overall flexibility of the cathctcr 10 is eithaaced with multiple balloo-is separated by ititerruptions which provide natural [lcx points for the cathctcr. V4nccn the balloons cxpc:ricnce the high prrfusion pressure, thcy bccotne more stiff. The reduced diameter internsptions provide for incrcascd flexibility at thcsc joittts, ildditional flexibility can be derivcd by providing the shaft 40 with variable stiffncss. This variability can bc produced by diffcrcnt materials for,n%ng the shaft 40 alon" iis lcngth or atteratively, tapering or othezurise varying the diameter of the sliaft 40. For exatnple, the shaft 40 can be progressively tapered frorn its proxi.ltaal etid 43 to its distal end 45 in order to pr.ovide a softer and miire flcxihle licat cxcnangc region 47.

AMENDED SHEET
..*.CA 02340237 2001-02-12 --- -':~F131#8~;,:::
~n ~nn f nnL.77Znnnn ntr ,nr r ir-rvn~rAAn T.~rrnn nt~~rnn rr r L~. ~ ~=~ ~~~--- -- -~ ~ ~--- .
RR r- i-Ã79-02-20Ã30: 90, 1$635.6 US991Q8455: DESCPAMG}

in aiiy of the fbrevoing ettthocliineiits of tlae catlieter 10, tlie iiiner ttloe 190 can be provicled with a central lumcn flcilitalinb introduclior-, ovcr a guidcwirc an(i providing a capability for the infusion of fluids through the catheter 10, With the intent of znaximicine hcat transfer with thc body fluid in a conduit feecjing a specific region of the body, any of the factors previously noted can be addressed to Frovicle structurat mclircalions to the foregoing embocliment_ti.
Of course changes in tt?e niaterial or size of any of the structural elements de.scribed can bc ti=aricd to sehicvc va+ious heat exchange propcrtaes. Realizing the many chattgcs whicll might bc contcmplatcd, onc is cautioncd not to limit this conccpt oiily to thc specific embodiments illustrated and discloscd, but rathcr to dctcrninc tno scope of the invcntion iA-th rc.fcrcncc to the followin, claims.

AUiEfVDED SHEET

.:;>: ::...:..,-:;
~r~ni....=..T .............................. r,n:,7-7-)nnrn Inu t3r1 I
\"'fltn'"14Ir'4 '7lllin/T nSl.,nn Ir 1 l.r1 n ~nr n.~.n-7 nn .-.-, 4+# : C-39tt6n~:c. 68 Ei+t --f;R+. .--. -771.1neo

Claims (53)

WHAT IS CLAIMED IS:

1. A catheter having an elongate configuration with a proximal end and a distal end, the catheter comprising:
an outer tube having an elongate configuration and a first lumen;
an inner tube disposed in the first lumen of the outer tube and having a second lumen extending between the proximal end and the distal end of the catheter;
portions of the inner tube defining a first fluid flow path extending along the second lumen between the proximal end and the distal end of the catheter;
portions of the outer tube and the inner tube defining a second flow path extending between the first tube and the second tube; and a plurality of hollow fibers providing fluid communication between the first fluid flow path and the second fluid flow path.

2. The catheter recited in claim 1, wherein:
each of the hollow fibers has a proximal end and a distal end;
the distal end of each of the hollow fibers has a fixed relationship with the distal end of the inner tube; and the proximal end of each of the hollow fibers has a fixed relationship with the distal end of the outer tube.

3. The catheter recited in claim 2, wherein the inner tube has properties for moving relative to the outer tube to vary the configuration of the hollow fibers extending between the inner tube and the outer tube.

4. The catheter recited in claim 3, wherein:
portions of the inner tube define a taper, the inner tube being axially moveable to bring the portions of the inner tube into sealing proximity with the hollow fibers.

5. The catheter recited in claim 1 further comprising:
a cap disposed over the distal ends of the inner tube and the hollow fibers.

6. The catheter recited in claim 1, further comprising:
a seal tube disposed inwardly of the proximal end of the hollow fibers and forming a seal with the distal end of the outer tube and the proximal ends of the hollow fibers.

7. The catheter recited in claim 6, wherein the seal tube extends proximally of the proximal end of the hollow fibers.

8. The catheter recited in claim 4, further comprising:
a seal tube disposed inwardly of the proximal end of the hollow fibers and forming a seal with the distal end of the outer tube and the proximal end of the hollow fibers; and the portions of the inner tube which define the taper are axially movable relative to the outer tube in the sealing engagement with the hollow fibers.

9. The catheter recited in claim 1, wherein the hollow fibers are adapted to receive a heat exchange fluid from the first flow path and to release the heat exchange fluid into the second flow path.

10. The catheter recited in claim 3, further comprising:
a seal tube disposed between the hollow fibers and the inner tube and having an inner diameter greater than the outer diameter of the inner tube, but sufficiently close to the outer diameter of the inner tube to form a liquid seal between the seal tube and the inner tube by capillary action.

11. The catheter recited in claim 10, wherein:
portions of the inner tube define a taper, the inner tube being axially movable to bring the portions of the inner tube into sealing proximity with the distal end of the seal tube.

12. The catheter recited in claim 5, further comprising:
a coating of insulation covering the cap at the distal end of the catheter.

13. The catheter recited in claim 1, wherein the hollow fibers are adapted to receive a heat exchange fluid from the second flow path and to release the heat exchange fluid into the first floor path.

14. A method for making a heat exchange catheter, comprising the steps of:
providing a first tube having a first lumen extending between a proximal end and a distal end;
inserting a second tube into the lumen of the first tube, the second tube having a second lumen;
connecting a plurality of hollow fibers in fluid communication with a first flow path extending along the second lumen of the second tube, and a second flow path extending along the first lumen of the first tube outwardly to the second tube;
and insuring that the second tube is at least one or axially and rotationally movable relative to the first tube to vary the configuration of the hollow fibers in order to facilitate heat exchange with the heat exchange catheter.

15. The method recited in claim 14, wherein the insuring step includes the steps of moving the second tube distally relative to the first tube to change the hollow fibers to a low profile state; and moving the second tube proximally relative to the first tube to change the hollow fibers to a high profile state.

16. The method recited in claim 14, wherein the connecting step further comprises the steps of forming the hollow fibers in a stack having a generally planar configuration;
wrapping the hollow fibers stack around the second tube; and inserting the hollow fibers into the distal end of the first tube.

17. The method recited in claim 14, further comprising the steps of fixing to the proximal end of the first tube a Y-connector having fluid communication with the second flow path.

18. The method recited in claim 17, further comprising the steps of attaching a locking device to the Y-connector, the locking device being operable between a first position permitting movement of the second tube relative to the first tube, and a second position inhibiting movement of the second tube relative to the first tube.

19. The method recited in claim 16, further comprising the step of putting the hollow fiber stack to form an end seal tapered radially inwardly to inhibit formation of stagnant flow regions around the fibers of the stack.

20. A heat exchange catheter, including:
an elongate shaft extending along an axis between a proximal end and a distal end;
first portions of the shaft defining an inlet lumen extending between the proximal end and the distal end of the shaft;
second portions of the shaft defining an outlet lumen;
a first manifold in fluid communication with the inlet lumen at the distal end of the shaft;
a second manifold in fluid communication with the outlet lumen of the shaft;
a plurality of hollow fibers disposed to extend between the first manifold and the second manifold in fluid communication with the inlet lumen and the outlet lumen; and the catheter being adapted to receive a heat exchange fluid at the proximal end of the inlet lumen, and to direct the heat exchange fluid through the hollow fibers to exchange heat through the hollow fibers.

21. The heat exchange catheter recited in claim 20, wherein the first manifold is disposed distally of the second manifold.

22. The heat exchange catheter recited in claim 21, wherein the outlet lumen is disposed outwardly of the inlet lumen.

23. The heat exchange catheter recited in claim 20, wherein the shaft comprises:
an inner tube defining the input lumen; and an output tube concentric with the input tube and defining with the input tube the output lumen.

24. The heat exchanger catheter recited in claim 23, wherein the first tube has a fixed relationship with the first manifold;
the second tube has a fixed relationship with the second manifold; and the first tube is axially movable relative to the second tube to vary the configuration of the hollow fibers.

25. The heat exchange catheter recited in claim 24, wherein the first tube is movable axially of the second tube to separate the first manifold and the second manifold, and to place the hollow fibers in a generally straight, parallel relationship.

26. The heat exchange catheter recited in claim 20, wherein the heat exchange fluid is a liquid.

27. A catheter adapted to exchange heat with a body fluid flowing through a body conduit, the catheter comprising:
a shaft having an axis extending between a proximal end and a distal end, the shaft having an input lumen and an output lumen;
a plurality of hollow fibers defining a heat exchange region of the shaft and collectively defining an outer surface of the heat exchange region;
the input lumen of the shaft coupled to the hollow fibers of the heat exchange region at a first location, the output lumen of the shaft being coupled to the hollow fibers of the heat exchange region at a second location such that a heat exchange fluid introduced into the input lumen will enter the hollow fibers of the heat exchange region at the first location and will exit the hollow fibers of the heat exchange region at the second location through the output lumen.

28. The catheter recited in claim 27, wherein the body fluid flows in a first direction through a body conduit and the heat exchange fluid flows through the hollow fibers in a second direction opposite to the first direction.

29. The catheter recited in claim 27, further comprising:
a clot inhibiting coating covering the hollow fibers.

30. The catheter recited in claim 28, further comprising:
a clot snare disposed in the first direction from the heat exchange region.

31. The catheter recited in claim 29, wherein portions of each hollow fiber defines a multiplicity of micro pores and the coating is formed by a clot inhibiting chemical included in the heat exchange fluid and leechable through the micro pores of the fibers.

32. A heat exchange catheter having a elongate configuration and extending between a proximal end and a distal end, the catheter being adapted for cooling the blood of a patient, comprising:
a heat exchange region of the catheter;
a plurality of fibers included in the heat exchange region, with each of the fibers having a hollow configuration and being adapted to receive a heat exchange fluid; and a coating disposed on the outer surface of the fibers to inhibit the formation of blood clots on the cooled fibers.

33. The heat exchange catheter recited in claim 32, further comprising a chemical included in the coating and having characteristics for inhibiting the formation of the blood clots.

34. The heat exchange catheter recited in claim 33, wherein the chemical includes heparin.

35. The heat exchange catheter recited in claim 33, wherein:
each of the fibers include a multiplicity of micro pores extending between the hollow interior of the fibers and the outer surface of the fibers; and the chemical is included in the heat exchange fluid and leached with the heat exchange fluid through the micro pores to coat the outer surface of the fibers.

36. The heat exchange catheter recited in claim 20, wherein the heat exchange fluid is a gas.

37. The heat exchange catheter recited in claim 20, wherein the heat exchange fluid is a cooling fluid.

38. The heat exchange catheter recited in claim 20, wherein the heat exchange fluid is a heating fluid.

39. A catheter adapted to exchange heat with a body fluid flowing through a body conduit, the catheter comprising:
a shaft having an axis extending between a proximal end and a distal end, the shaft having an input lumen and output lumen;
a heat exchange region disposed at the distal end of the shaft and including a plurality of hollow fibers each having an outer surface adapted to be operatively placed in heat exchange relationship with the body fluid flowing in the first direction;
and the hollow fibers being disposed in fluid communication with the input lumen and the output lumen to facilitate a flow of heat exchange fluid through the hollow fibers to cool the body fluid in the conduit.

40. The catheter recited in claim 39, further comprising:
a first manifold included in the heat exchange region and being in fluid communication with the input lumen of the shaft;
a second manifold included in the heat exchange region and being in fluid communication with the output lumen of the shaft; and the hollow fibers extending between the first manifold and the second manifold in the heat exchange region of the catheter.

41. A catheter adapted to exchange heat with fluid flowing through a blood vessel, comprising:
a catheter body having at least one heat exchange fluid supply lumen and at least one heat exchange fluid return lumen; and plurality of elongated hollow heat exchange elements communicating with the supply lumen and with the return lumen, each element defining an outer heat exchange surface across which heat can be exchanged with a fluid flowing in the blood vessel, a heat exchange liquid circulating through the catheter without mixing with blood in the blood vessel.

42. The catheter recited in claim 41, wherein each heat exchange element defines a respective proximal end and a respective distal end, and the proximal and distal ends of the elements are connected to the catheter body.

43. The catheter of claim 42, wherein the distal ends of the heat exchange elements are connected to a distal manifold communicating with the supply lumen.

44. The catheter of claim 43, wherein the supply lumen is centrally formed in the catheter body.

45. The catheter of claim 42, wherein each heat exchange element defines a respective element body between the respective proximal and distal ends, the element body being spaced from the catheter body.

46. The catheter recited in claim 41, wherein each heat exchange element defines a respective proximal end and a respective distal end, and the distal ends receive heat exchange fluid from the supply lumen and the proximal ends return heat exchange fluid to the return lumen.

47. The catheter of claim 46, wherein the supply lumen is centrally formed in the catheter body.

48. The catheter of claim 47, wherein each heat exchange element defines a respective element body between the respective proximal and distal ends, the element body being spaced from the catheter body.

49. The catheter of claim 46, wherein each heat exchange element defines a respective element body between the respective proximal and distal ends, the element body being spaced from the catheter body.

50. The catheter of claim 41, wherein the supply lumen is centrally formed in the catheter body.

51. The catheter of claim 50, wherein each heat exchange element defines a respective proximal end, a respective distal end, and an element body therebetween, the element body being spaced from the catheter body.

52. The catheter of claim 41, wherein each heat exchange element defines a respective proximal end, a respective distal end, and an element body therebetween, the element body being spaced from the catheter body.

53. The catheter of claim 41, wherein each heat exchange element is made of a flexible material.