CA2182864C

CA2182864C - Mechanical thrombus maceration device

Info

Publication number: CA2182864C
Application number: CA002182864A
Authority: CA
Inventors: Frank Kotula; Timothy Claude
Original assignee: Microvena Corp
Current assignee: Microvena Corp
Priority date: 1994-02-08
Filing date: 1995-02-08
Publication date: 1999-03-30
Anticipated expiration: 2015-02-08
Also published as: DE69500959D1; DE69500959T2; WO1995021576A1; CA2182864A1; US5569275A; EP0743837B1; ATE159651T1; JPH09508554A; EP0743837A1

Abstract

The present invention provides a mechanical medical device useful for macerating thrombi or the like. In one embodiment of the invention, the device includes a rotor (50) retained in a distal housing (70) having at least one port (74, 75) for ejecting fluid therethrough. The port or ports in this embodiment are sized and positioned so that the surface area of the ports is not evenly distributed about the circumference of the housing. For example, the housing may include a single port, two or more equiangularly spaced ports of different sizes, or two or more ports of the same size spaced unevenly about the circumference of the housing. When a fluid is ejected through the ports, the housing will tend to deflect toward one side of the vascular channel. In accordance with another embodiment, the device includes a plurality of rotors (50A, 50B, 50C) spaced along a common shaft (10) for rotation therewith. In a third embodiment of the device, fluid directing means (e.g. 240) are provided for directing fluid discharged through a port in the housing back toward the rotor.

Description

wo ssnls76 ~ 3'l0l776 2 ~ ~2~64 MECHANICAL THROMBUS MACERATION DEVICE
FIELD OF THE INVENTION
The prese"l invention provides a medical device for use in vascular procedures. The device is particularly useful in the mechanical maceration of 5 a ll " o, - ,t~us or the like.
BACKGROUND OF THE ll~tVENTlON
It is well known that the presence of furei~-~ solid matter within an individual's vascular system can have serious adverse effects on an individual's health, either directly or inJirecll~,r. Such solid matter most 10 co,.,-~,only takes either the form of a ll-ro--lbus, i.e., ,iela~ ous, free-floatin~
matter within a vascular channel but not adhered to the channel itself, or dll.eloma, which is most co,r---o--ly a buildup of plaque or the like on the wall of a vessel. A wide variety of techniques are known for removing or breaking down such matter within the vascular system. Some techniques, known as 15 ll,ro"~l,olytic therapy, utilize phar,aceutical CGIl,~ounds, e.g., urokinase or streptokinase, to help dissolve such foreign matter.
Other techniques take a -,ect,anical approach and dtlem,~t to dislodge the solid matter from the walls of the vascular system, if necessary, and then remove the solid matter from the vascular system by means of suction or the like. In dislodging plaque from vascular walls, an elongate wire with one or more scraping blades adjacent the distal end is rotated within the vascular channel. By moving the roLdling blades axially into contact with the plaque, the blades will tend to dislodge it, per.,~illi"g the dislodged particulate matter to be withdrawn from the vascular system by means of suction through a catheter or the like. A similar technique may also be used to break a relativeiy large ll"ombus into a number of smaller pieces which may then be extracted by aspiration.
This prior art technique does have a number of significant disadvantages, though. First, the rotating blades, which commonty rotate at between about 2,000 and about 35,000 rpm, are exposed, therefore posing a significant risk of puncturing the wall of an artery or a vein. It is esli"~ated FROt1 FORRESTERS LCNDON 5. 17. 199~ 19 P. 14 ~ r ~ 2 ~ 6 4 that thi~ occur~ ln up to o~-third of the procedures carried out with 6uch A rotating blade, po~ing serlou~
hoalth rl~s each time 6UCh a dev~ce is u~ed.
Another disadvantage Or this procedure i6 that lt i6 unable to rinCly grind tbe partlculate matter; it simply tendfi to di~lodge relatively large piece~ of the bu11t up plnque or break a large thrombu~ into a sm~ll number of individual plece~ which remain ralrly lar~e them~elve8.
8ecau~e thi6 ~ree-floatinq ~olid matter would tend to for~
additional thrombl ir permltted to remain in the va~c~lnr 6y6tem, they mu~t be removed. A~ noted above, thi~ i8 mogt commonly done by attempting to d~aw the thrombl out of the ~ody through a ca~leter under ~uction. In ~o with~rawing the thrombi, one mu~t nece6sarily withdraw a ~ign$f icant amount o~ blood as well. The volume of blood withdrawn from the paticnt mu~t obviou~ly be r~placed, ~o additional blood suppliec mu~t be availabl~ for tran~u~ion into the patient und~rgoin~ thi~ procedure.
WO-A-922253 r~lates to a ~elr-cen~rlng ~chanlcal m~d~c~l device ror ~reaXing down thrombi, whic~ comprlses a ro~or ~aintained in a housing, at the ena of a~ elo~gatcd fl~xlble ~haft, the rotor and housing ~elng ~alntained Centrally within a ves~l by mean~ o~ equiangularly ~paced port~ throughou~ ~he hou~ing.

~UMMARY OF THE INVENTION

According to the pres~nt invention, there is provlded a ~echan~cal thrombu~ macera~lo~ device compri6ing ~ . an elongate, flexible 6haf~ having proxi~al and dl~l ends, the ~ha~t being adapt~d to be guided along a va~Cul~r path and being rotataPle withln a va6cular channel having a v~gcular w~ll;
b. a rotor afflxed to the 6hart ad~acen1 ~he di~tal end thereof for rotation therewith;
c. drive ~enn6 for rapidly ro~ing the ~ha~t; and NOEO S~

FR011 FORRESTERS LI~NDON 5. 17. 1996 I:S: 19 P. 15 ~ ' ' '';
2 ~ ~286~

- 2a --~ , a ro~or hou6ing c~rried aPaut the rotor And within which the rotor rotate~, the hous~ng comprising a generally cylindrical subst~ntlally 3u~rounding the rotor and having at lea6t one port rorm~d th~rein, the port o~
port~ being ~ized and positloned about the circu~eronce of the housing such that when a fluld i~ e~ected through thc po~t6 within a vascular channel, the nousing will tend to deflect toward one side of the va~cular c~-~nnel to per~it the d~vice to be steered ~urlng deployment ther~a~ wlthln a patient's vascular ~y~tem.

A me~ical device according to one embv~iment of the pre~ent invention generally incluae6 an elongate, ~lex~le shaft which may be gulded along a v~scular p~th. A rotor, or "impel l er", having blades is affixed to the shaft adjacent its dis~al end. Drive means are provided ~or rapidly rotating the ~h~ft and the rotor att~ched to the ~haft. The rotor i~ retained within a rotor hou~inq nnd rotates therein. Th~ rotor hou~ing co~pri~es a g~nerally cylindrical wall substantially 6urroundlng the rotor and haYing at least three ports spaced equiangularly about the circum~erence of the housing. As the rot~r i~ rotated, it will tend the draw ~lUi~ i.e., blood, into the hou~ing ~
a proxlmal direction and expel the rluid ou~ through the portC. Thls fluid then tends to be arawn b~ck lnto the di~tal end o~ the hou~ing and through the rotor ~galn, ~etti~g up a recirculating vortex wh~ch repeatedly pa~se6 the rluid acro6~ the blAdes.
When the ~luid i~ ejec~e~ through the ports in tho housing within a vas~ular channel, t~e ~luid will t~nd to act agalnst the wall Or the ch~nnel. Thi~ ~n tur~ tends to mainta~h the housing in a posltion spaced away from the ~urrounding vasc~lar wall. By spacing the ports equiangularly about th~
~ 0 5~

.. ,, j, ~_ FROt~l FORRESrERS LONDON S. 17. 1956 13:20 P. 16 ~,.. .. --2 1 3286~

clrcu~ference of tho housing, the ~orce exertRd by the ejected flul~ Wlll tend to ~aint~ln ~he ~ou~ing and t~
rotor c~rried therein ln a positlon subst~nti~lly centered withih the vascular chann~l.
ln an alternati~e embod$ment, the port of port~ are sized and po81tioned ~o ~at th~lr ~urf~ce ~rea ~ not evenly distributed aPout t~e clrcumrerence of the housing, For example, there may ~e only a ~ingle port, two or mo~c equiangularly ~paced por~s of dlfferent slzes, or ~wo or ~ore port6 of the ~ame slze ~paced unevenly about thc circu~feren~e o~ th~ hou~lng, When c rluid i~ e~ec~ed through the port~ wlthin a vascular ~h~nnel, ~he houslng will ~end to ~eflect towar~ one ~ide o~ the v~scul~r channel. Thi~ permits ~n op~r~tor to effectLvcly ~teer thc device durlng ~eploymen~ thereor within a p~tl~nt~ G
va~cular sy~tQm.
In accordance w~h another alternative ~m~o~ -nt of the present invention, there i~ provided a mechanic~l thrombu~ m~ceratLon device compr~6ing;
a. an elongate, fl~xlble chart having proximal and d~tal ends, the shaft belng adapted ~o be gu$ded nlong a va~cular path and belng rotatable withln a vascular chnnn~l hAving a va~cular w~ll;
b. a rotor af~lxed to the ~ha~t ad~acent the di6tal end. thereof ror rotation therew~'ch;
c. dr$ve means for rapidly rotatlng the shaft; nnd d. a rotor hou6ing oarrled about th~ rotor ~nd within Wh~Ch the rotor rotates, the houslng co~pri~ing ~
generally cylindr~ cal wall 6ub~tantially ~urrounding the rotor, the wall haV~ng an axi~ an~ hav~ ng at le~t three elongate p~rts formed ~herein, thc po~ts being ~paced generally egui~ngularly abou~ the c~rcum~er~nce o~ the h~using an having a major axis which i~ orlented obliquely with ~e6pect to the axi6 of the hou~ing at an ang le Or ~rom 20O to 450.

A~FP~D Stt FRO~I FORRESTERS LONDOI~ 5. 17. 1996 1:5:21 P. 17 ~ 1 82864 There i~ furthcr providcd a ~ h~nlcal thrombus maceration devic:e comprl61ng:
a. an elongate, flexible ~h~t hav$ng p~o~ir~l ~n~
dl~tal ends, the sha~t ~eing adapted to be guided along n va~cular path and being rotatable within a va~cular channel having a vagcular w~ll;
b. a plurality of rotor~ ~rfixed to th~ 6h~t for rotation therewith, at least two rotors having blades, the rotorR being 6paced apart rrO~ one another along the ~haft;
c. a drive means for rapidly rotating the shaft;
and d. a rotor hou~ing enclo~ing ~ rotor and within which 6aid rotor ro~ate~ he houslng compri~;ing 8 generally cyllndrical wall substanl;ially surrounding the rotor and an int~ke port.
~ here 1~ ~till furth~r pr~vided the de~ ce of Claim 10 wherein said rotor~ are ca~rle~ along a distal ~egment of the ~hart ar~d the rotor hous~lng enclose~i all of th~
rotor~ and lnclude6 A ~irLt dixcharge port pa~ing through the wall of ~he hou~ing at a location proximal of th~
di~tal-~ost rotor and an int~e port di6po~ed dl~tally of the proximal-most rotor.

EF DE~CRIPTION OF ~IT~ D~AWINGS

Figure 1 ifi ~ per6pective, partlally broken away view of a medical device of the invention;
Figure 2 i6 a per~pective view i~ p~rti~l cro~
6ection of a di~;al portion of the de~rlce of Figure l;
Figure 3A i~ a ~ide vlew or the rotor hou~ng o~
the device of Figure l;
Flgure 3B i a top v i e~ Or the rotor hou~lng o~
rigure 3A;

A~ENOEDS~E~' , ~ , "

FRol~l FORRESTERS LONDOI~ S. 1~. ~9'36 13:21 F~. 18 ,,,, . ~ ~
~ 1 ~2~64 Figure 4A 18 a aid~ ~i~w of a p~e~erred ~lho~ ~nt of a rotor of the lnvention Figure 4B i6 a ~ifl~ view f th~ rotor of Figure 4A
rotationally di~place~ about it~ axl~ approxlmately go~
from the ~iew o~ Figure 4~
Figure 5 16 a cro66-6ectlonal vlew o~ a prcferr~d embodiment of a rotor housing of the lnventlon;
Figure 6 i8 ~ perspectlve v~e~ of the dlstal portion of an alternative em~o~l~ent of the in~cnt~on utilizing a guidewire tr~cki~g channel;
~ igure 7 i~ a cro6~ ~ectional vlew of a preferred ~rlve mean~ ror use with the present lnventioni AI~ENDED SHEEl .. . ~. . , . _ . . .. .

WO 9S/21576 PCI'IU:~95~17/6 _4 21 ~2864 Figure 8A is an end view of an allerl,ali.Je e--lbGdi,.~ei~ of a rotor housing of the invention;
F;gure 8B is an exploded side view of the housing of Figure 8A, as asse" ,~led;
Figure 9 is an exploded perspective view of a turbine for use in the drive means of Figure 7;
Figurs 10 is a side view in partial cross seclion of a distal portion of an allet"ali~/e embodiment of the invention;
Figure 11 A illustrates an alternative embodiment of the embodiment of Figure 6, utilizing an alle,--ali~e guidewire tracking chan.~el;
Figure 11B is a top isolation view of a distal portion of the embodiment of Figure 1 lA;
Figure 11C is a side isolalion view of a distal portion of the embodiment of Figure 11 A;
Figure 12 illustrates an alternative e.. ,bodi".~nl of a rotor housing of the invention;
Figures 13A and 1 3B are a side elevational view and an end view, respectively, of another embod;,~,euL of the invention, which employs a multi-stage rotor design;
Figure 14 is a side view in partial cross section of a distal portion of yet another embodi",ent of the invention;
Figure 15 is a schematic view of a shaft for use in one embocli",ent of the invention;
Figure 16 is a side view of a distal portion of another embodiment of a housing of the invention;
Figure 1 7A is a side view of a further embodiment of the present invention employing an inflatable balloon;
Figure 1 7B is a side view of the embodiment of Figure 1 7A with the inflatable balloon in its inflated state;
Figure 18 is a side view of a further embodiment of the invention which uses an exhaust directing means;

wossnls76 ~ ss~-"6 2 1 82~64 Figure 19 is a side view of another embodiment of the invention which uses an exhaust directing means;
Figures 20A and 20B are a top view and a side view, respectively, of - an embodi-~-ent of the invention which is gene,ally self-s~eeral~le;
Figure 21 is a sche",a~ic side view of a further additional embodi.. ,enl which can be used to remove ...acelated II,r~ i; and Figures 22A and 22B are top and side elevational views, respectively, of anoll.er embodiment of the invention which is generally self-stee.aLle.
DETAILED DESCRIPTION
One ~r~ferreJ embodiment of a medical device of the invention is shown in Fi~ures 1-4. This device generallv includes an elongate, flexible sha~ 10 carried within an elongate, generally tubular casing 20; a rotor 50 affixed to the shaft and carried within a rotor housing 70; and a drive means 100 operaLi-~Qly connected to the shaft for roldlin!3 the shaft.
The shaft 10 is elongate and generally cylindrical in shape and has a distal end 12 and a proximal end 14 ~Figure 7). The shaft is sized to be threaded, along with the rest of the device of the invention, alony a vascular path within a palieriL's vascular system. The shaft will co~ nGnly have an outer dia,-leter of between about 0.25 and about 1.5 mm, with a range of about 0.35 to about 0.65 mm being ~.,ere.. eJ. The length of the shaft can be varied fairly widely, depending upon the general types of locations within a vascular system intended to be accessed with the device. As a general rule, the shaft is clesi-ably between about 50 cm and about 150 cm long, with a range of about 80 cm to about 100 cm providing a device which is 25 useful for a wide variety of applications.
The shaft is desirably highly flexible so that it may be threaded through a pabent's vascular system with ease. The shaft may be made of any of a wide variety of materials well known in the art, such as stainless steel. In one preferred embodiment, however, the shaft is formed of a shape memory 30 alloy, such as a NiTi alloy. The use of such alloys in medical devices is known in the art and need not be discussed in great detail here. One important property of such alloys is that they exhibit superelasticity, i.e., they wo s~nls76 P~ 776 -6- 21 ~864 may be deflected tO a much gteater extent than most other metals, such as stainless steel before showing any permanent, plastic .leforl,.dlion. This prope, Iy is explained in some detail in U.S. Patent 4,926,860 (Stice, et al.), the ~achil~gs of which are incorporated herein by reference. In the present 5 e.,ll~od;.neot, this permits the shaft 10 to be guided along a tortuous vascular path without introducing a permanent "set" in the wire. Accordingly, when the shaft is guided to the desired localion and rotated (as desc,ibed below), its rot~,lion will be centered almost exclusively about the axis of the shaft.
If a non-shape memory alloy, such as stainless steel, were used to 10 form the shaft, the shaft would tend to take a permanent set, i.e., undergo plastic defo,--,dlion, as it is guided along a tortuous vascular path. This would introduce a degree of curvature in the distal portion of the shaft 10.
When the shaft is rotated, it will not rotate merely about its axis, but will also tend to spin so"lewl~dl wildly due to the curvature of the wire. If the shaft 15 includes a rotor for de~raJing solid matter within the blood stream, this "whip" can readily lead to puncture of the vessel walls, as noted above.
In an alle."ali.~e embodiment, the shaft 10 is formed of a "drawn-brazed strand" (DBS) cable. Most cables, particularly those used in medical applications, co-,.p-ise a plurality of independent wire strands which 20 are wrapped in a generally helical fashion about a central core wire. Although such a cable does tend to resist plastic defo~l,ldlion somewhat better than a single, unitary wire formed of the same ."dlerial at the same dia---eler, the central wire strand of such a cable will tend to undergo plastic deformation to an extent proportional to that experienced by the larger dia.nel~r unitary wire.25 In a D8S wire for use in an embodiment of the invention, a plurality of separate strands are wrapped in a helical fashion, but no cenlral wire strand is employed. By eliminating this central wire, the primary cause of "whip" is eliminated, thereby substantially eli-l,ind~ g whip in the shaft when it is subjected to rotation. Once the individual wire strands (not shown) of a DBS
30 wire have been twisted about one another in a helical fashion, it is desirably drawn under pressure at high temperatures. As will be understood by those skilled in the art, this drawing and brazing of the wire can be used to meld wo 95/21576 rcl~/usg5/om6 21 82a6'~

the individual wire slldll~ls into a single wire having a larger .lia-..eter. Such a shaft generally ap,~ears the same as a solid wire, but the wire tends to retain some of the .-,icro~l..lcture associated with the intertwined wire strands, yielding a wire with a tensile strength co.nparable to that of a cable. The individual wire :,lrands used to form a DBS wire may be formed of any suitable .nal~,ial. As with the unitary, single strand shaft Jesc.i6ed above, the DBS shaft may also be for...ed of a shape nlelllGI~/ alloy such as a NiTi alloy, if so desired.
Figure i 5 illustrates one particularly ~,referred embodiment of the shaft 10 10. The main body of the shaft may be as dese,il)ed above, but the shaft includes a weake~ point along its length which will selectively structurally fail in the event of a malfunction. In the en~bocli.,.ent of Figure 15, the shaft 10 is fo,--,e~l of two shaft seyl~l~n~s 10A and 10B. these two shaft sey,-le--ts are joined together by a shear link 16. This shear link includes a reduced 15 cliamt~ter pGI liGII where it joins the two links, derillL)~ a relatively weak area of the link. This reduced dia",e~er portion should have a torsional strength less than that of the main body of the shaft so that will tend to break under torsional shear before the rest of the shaft will fail. This makes the device even safer in that the shaft will break at this link 16 when the shaft 20 encounters undue resisla,~ce to turning, such as when there is some blockage of the rotor or some other unforeseen malfunction occurs.
The shear link 16 may be posilioned at any suitable point along the length of the shaft. In the embodiment shown in Figure 15, the link 16 is ~osilioned almost i"""edic,l~ly proximally of the housing 70. It should be 25 understood, though, that the link 16 could be placed elsewhere such as a.J~acent the joint between the shaft and the drive means 100 described below.
As noted above, the shaft 10 is desirably carried within a shaft casing 20. The sha~ casing is desirably generally tubular in shape such that the - 30 shaft 10 may be retained and roldled within the casing. As shown in Figure 1, the shaft casing 20 desirably extends along and encloses subsl~nlially the entire length of the shaft between the drive means 100 and the housing 70.

wossnls7c P~ ,9S~'~,1776 21 82~64 The shaft 10 should be rolald~le within the shaft casing so that, as the drive means 100 causes the shaft to rotate, the shaft casing 20 ren~ains suhsl.q~.lially stationary with respect to the drive means. The shaft casing should be flexible and sized to permit it to be threaded along a vascular path as the device of the invention ts posilioned within a patient's vascular system. In a pr~re"ed embodiment, the shaft casing co,n,G.ises a tubular outer sleeve 22 forl.,ed of a biologically inactive polymeric compound, such as polyurethane or the like.
Figure 6 ~Jeph-l~ an dll~n,~ e ~ odi."e"t of the tubular outer sleeve 22 shown in Figures 1 and 2. In this embodiment, the outer sleeve is generally the same as descril.e-J above in connection with Figures 1 and 2, but the outer sleeve further includes an arcuate ~)roje_lion which extends ye.,erall~ radially olJl~arJly toward one side of the sleeve 22, as shown.
This projeclion 24 includes a guide wire l~acl~ing chadn"el 28 which may extend along substantially the entire length of the pr~jeclion. This tracking channel permits one to simply direct a guide wire to the desired location within a patient's vascular system and then direct the distal end of the described embodiment of the present invention to that location by passing ths guide wire through the channel 28 so that the device follows the path of the guide wire accurately. The projeclion desi,a~ly ~em,inates at a position proximally of the rotor housing 70 so that it does not interfere with the flow of fluid during ope~dlion of the device.
Figures 11A-11C illustrate an all~r"ati~e embodiment of the invention utilizing a modified guidewire tracking channel 28'. In the embodiment shown in Figure 6, the channel 28 is positioned in a projection 24 which extends along the casing 20. In Figures 11, though, there is no such separate projection, but rather the casing 20 is a dual lumen catheter having a larger inner lumen wherein the shaft 10 is disposed and a smaller second Iumen which defines a guidewire tracking channel 28', with an inner wall 24' of the casing sepa(ali-1g the two lumens. This tracking channel 28' extends along subsla~,lially the entire length of the casing 20, but ~e-.nindles slightly proximally of the distal end of the device.

WO 95/21~6 r~ 5S~ 6 9 2 1 ~2864 As best seen in Figure 11 C, the chal1nel 28' tapers radially outwardly in a distal Ji.eclion, leading a guidewire carried therein to relatively gradually slope radially outwardly until it is clear of the casing. In order to avoid too abrupt a change in the relative Grier,~lior. of the glJidewi~e and the casing 5 where the 9~ ~svlire exits the casing 20, the cl~annel 28' tapers outwardly ata relatively small angle ~p, which is desirably no more than about 35 and preferably bel~ccn about 1 and about 5. An e-,lLocli.ne..t having an angle of about 3 has been found to work well.
This tap~ri-~g will define a generally elongate exit opening 27 in ~e 10 casing where the guidewire is to exit the tracking chan,~el 28'. The opening 27 may extend along both the distal ses-.,enL of the casing 20 and a proximal portion of the rotor housing 70, as shown in Figures 11. In the en,L,odi.~enl:, which include one or more discharge ports 74 in the housing, as detailed below, the exit opening 27 is pf~terd~ly iiSpose~l between the ports 74. This 15 will help direct the distal po, liO-- of the guidewire between the ports and avoid any i-,l~,r.,.ence by the guidewire of the fluid flow established by the ports, which is explained below The guidewire tracking channels 28 or 28' shown in Figures 6 and 11 are useful when a device in accordance with the invention is to be deployed 20 through a tortuous path or in perrG.-..;ng a cori~tdlat~ral introduction. As such, this feature can be used with any of the other embodiments of the invention desc-ibed herein. Hence, although the embodiments of Figures 6 and 11 illustrate rotor housings 70 which include a plurality of exhaust ports 74, it is to be uncJer~tood that the guidewire tracking channel 28 or 28' can 25 also be used with embodi.nents which do not include any ports 74 (e.g. the self-pumping version of the invention illustrated in Figure 21).
In a particularly prefe.-ed embodiment, the shaft casing 20 includes an elongate inner bearing 26 J;s~osed l~l~/e~.- the outer sleeve 22 of the casing and the shaft 10 to reduce r-ic~ion between the outer sleeve and the shaft - 30 In one embGdi..,ent, the bearing is desirably free-floating, i.e., it is not attached to any other element of the device, but rather is simply retained between the outer sleeve and the shaft. Although any of a wide variety of WO 9S/215~6 ~ ',1776 10- 2~2864 structures may be employed, one particularly useful design utilizes a helical coil, as shown in the drawings. Such helical coils are well known in the art and are most colrl..,Gnly used as structural elen.enls of guide wires. They generally con~- ise an elongate wire strand, usually stainless steel wire, 5 which is wrapped in a helical fashion about a ,and,el and then removed from the ~-ard~el.
In prior art devices wherein a rolalii~g shaft is Ihr~aJed through or carried within a catheter, a bearin~ generally is not employed. When the catheter and shaft of such a device are guided into position within a vascular system, the device almost always has to follow a curved path, and this path may include one or more relatively sharp angles. Where the path curves, the shaft tends to abut agairisl the inner wall of the call.eter, which derines the path which the shaft must take. When the shaft is rl.ldte.l, there tends to be friction b~ e.- the shaft and the catheter wherever such contact occurs.
Not only will this friction obviously tend to generate heat, but it also introduces torsional strain in the shaft by providing resbl~nce to rotation at the point of contact. Although these disadvantages may have only marginal deleterious conse.~uences at lower rotational spee~ls, they tend to be problematic at higher rc,ldlio.lal speeds. At higher speeds, the heat gene-~led by friction could lead to localized areas of elevated temperature wherein the te,l-~erdlure is high enough to begin de~rd.li-lg the blood within the vascular system and/or the surrounding tissue of the vascular wall. Ful lhenllore, the torsional strain placed on the shaft could well reach a level sufficient to cause catastrophic structural failure of the shaft.
By employing an inner bearing 26 between the shaft and the outer sleeve 22, one can minimize these adverse effects. Wherever a curve in the path of the device occurs, the shaft will abut against the bearing, which in turn bears against the outer sleeve 22, thereby avoiding direct contact between the rotating shaft 10 and the sldlionar~r sleeve 22. The free-floating bearing acts as a buffer between these two parts, minimizing friction. By reducing friction, the excess heat generated and the torsional strain placed on the shaft are both kept to a minimum. Furthermore, to the extent that WO 95/21576 PCI'IIJS95101~76 2 1 ~28~4 friction intro~ ces any u..~lesired heat, the coil, which is ~enerally formed ofa metal such as stdnl~ss steel, will tend to act as a heat sink and more evenly distribute the heat to further .,.ini,.)i~e loc~ ed increases in - tsmperature attributable to the friction. Accordingly, this reduces d~,.. age to 5 blood and tissue as well as greatly reducing the likelihood of experiencing cald~LIopll ~ failure of the shaft.
Although in the embodiment shown in Figures 1-10 the bearing 26 is free-floatin~, Figure 14 illusl-a~es an~ll-er embodiment u/l.erein the coil is fixed at at least one end. In the e..lbGd;...enl of Figure 14, a coil is also used 10 as the inner Lez.in~ 26, but the distal end of the coil is dllache~J to the proximal end of the housing 70. The coil and the housing may be attached by, for exa-l,?lE, a braze or solder joint 23; an adhesive ..,aterial such as anepoxy could be used i--alead if so d~;,i~l. For reasons outlined below, it is pnafe,.~d that fluids be ,oen,-ilLt:d to flow between the housing 70 and the shaft casiny 20. Accordingly, the joint 23 between the coil 26 and the housing 70 should not define a fluid-tight seal between these two elements, but should instead simply structurally connect the coil to the housing.
If so desired, a standard "Y-type" connector may be attached to the outer sleeve 22 toward its distal end. These types of connectors are well 20 known in the ",edical field and need not be lisclJssed at great length here.Generally, though, they include a body portion 32 and an inlet tube 34. The body portion 32 is generally axially aligned with the outer sleeve 22 while the inlet tube 34 is angled distally outwardly from the body portion 32. The inlet tube 34 is in fluid communication with the interior of the shaft casing 20, 25 per.,.illing one to introdur;e any of a wide variety of fluids into the casing. In the embodiment shown in Figure 7 (discussed at length below), the Y-type connector is replaced by an infusion line 34', which may be formed of a length of flexible tubing or the like. The infusion line may be affixed to the sleeve 36 of the housing of the drive means 100 by means of a Luer fitting 30 35' or the like. Like the inlet tube 34 of the Y-type connector, the infusionline 34' is in fluid communication with the interior of the shaft casing 20.

wo ssnls7c P ,~ 9~/0l776 -12- 21.~864 Fluids which may cG~Illllonly be used in connection with the present device include saline solution, co,.l.dsl medium (for enhancing'the rd~l;og-aphic visibnity of the device) and ri~ri.)olytic solutions (for medically breaking down fibrin, a major component of most II,rombi). When such a 5 fluid is introduced through the inlet tube (Fig. 1) or infusion line ~Fig. 7) and i.,;e_ted into the shaft sleeve, it will tend to flow out of the distal end ll.ereof. This flow of fluid tends to act as a lubricdling and cooling medium to further reduce the undes;-able effects c~used by r.i~liGn as the shaft is rutd~e.l.
A rotor 50, which may also be refer,ed to as an "impeller," is affixed to the shaft 10 adjacent the distal end thereof for rolalio" therewith. As best seen in Figure 4, the rotor 50 ge--erally includes a central body 52 having at least one blade ~6 carried thereon. The central body 52 is desirably generally tubular in shaps, having a cylindrical aperture 54 15 eklendi..g through the body along the axis thereof. As explained in more detail below, this aperture 54 is intended for receivin~ a portion of the shaft 10 adjace-.t its distal end 12. Any number of blades 56 may be carried about the central body 52. In the pre~e,lad embodiments shown in Figures 2 and 4, the rotor 50 includes a pair of generally did",el.ically opposed blades 56 20 which extend generally radially outwardly of the central body 52. In the embodiment shown in Figure 2, each of the blades is semi-elliptical in shape and is positioned dia...~lrically opposila the other blade. Each blade is desirably positioned within a plane which obliquely intersects the axis A of the shaft, and the o,~",osile blade is suL.atc.nlially a mirror ima~e of the first 25 blade. This construction is not unlike that of the propellcr of a prop-style .,i.~,lane, the oblique orientation of the blades 56 causing fluid to be thrust generally axially rearwardly of the rotor when the rotor is caused to rotate.
A particularly preferred embodi",enl of a rotor of the invention is shown in Figures 4A and B. In this embodi",enl, as in the previous one, the 30 blades extend generally radially outwardly of the body 52 from Llia"~el.ically opposite locations. However, in this "screw type" rotor, each blade spirals in a generally helical fashion along the length of the body. In the embodiment WO95/21576 I~ J'3S,'01716 2 1 s~2~6l~

shown, each blade eAltznds about approAi.,.dlely 180~ of the circu---rt rence of the body 52 between the blade's proximal 58 and distal 60 énds. The rate at which the blade 56 follows around the circu--.fere-)ce of the body along its length can be varied as desired. In one embodiment which is found 5 to be parficularly useful, a plane within which a segment of the blade lies ;so.ienled at an angle theta (~3) of approxi."alely 40 from a plane orthogonal to the axis A of the body 52.
As noted above, one of the major cGm~one"l~ of most Ill.o..lbi is fibrin. As the name implies, fibrin is generally for.~-e~J of elongate strands of 10 a protein~ceous ",aterial. When the rotor 50 is rol~,~ed within a vascular channel to break up a l~-r~fil~us, fibrin will tend to become w.~p~,ed around ~e body 52 of the rotor if the rotor is not ~ccele.dleJ from an initial alali~al-/ poailion to full rotationa! speed quickly enough. As .~esc.iLad in more detail below, the drive means 100 of the invention is intended to permit 15 sufficient torque to be a~.~,lisd to the shaft 10 to reach ,-,aAimum rolaliooa speed rather quickly to avoid this problem.
If so ~Jesired, a sharpened leading edge 62 may be provided adjacent the distal end 60 of each biade 56. In this embodiment, the leading edge of the blades do not lie in a plane orthogonal to the axis A of the body 52 as do 20 the trailing edges 64 at the proximal end 58 of the bla~es. Instead, the leading edge lies within a plane which is angularly displ:~ced ftom an orthogonal plane through an angle ~Y. This angle o~ is desi(ably between about 30 and about 60, with a range of between about 40 and about 45 being preferred. This provides a sharp, acute angle at the distal end of the blade, 25 pe,n,illing the sharpened distal edge of the blade to slice the fibrin before it can become twisted about the rotor.
The rotot may be affixed to the shaft by any suitable means. In a preferred e",bGdi",el,t, a distal portion of the shaft 10 is received within theaperture 54 for."ed in the body 52 of the rotor. The shaft may then be - 30 permanently adhered to the rotor in any desirable fashion, such as by brazing or by means of a curable, biologically inert ce",entilious "-al~rial.

wo 9~ 576 ~ 35/Cl716 -1 ~ 2 1 ~ 2 ~ 6 4 A II.,o"lbeclumy device illusl-d~d In Figures 1-4 also includes a rotor housing 70 carried about the rotor and within which the rotor r~les. The housing co-n~,rises a g~llerdlly cylindrical wall 72 having an inner .lia,..etergreater than the outer dia.n~ter of the rotor 50 so that the rotor may freely 5 rotate within this housing. In a particularly prere..ed embodiment, the inner dia-.-~er of the housing 70 is only slightly greater than the outer diameter of the rotor 50. This close proximity Lel~e~, the rotor and the wall 72 of the housing increases the shear force ar~lied to a fluid ~ass;--~ through the housing as the rotor is ruldted. This he;~l,le..ed shear force will serve to 10 further break up the ll--u--~Lus carried within the blood, ~e..,.illin~ the rotor to more rapidly degrade a ~ ,.ubus entrained in the fluid into sufficiently small ,~,a. Iicles. The axis AH of the housing 70 is desirably s~hs~ntially aligned with the axes of the rotor 50 and shaft 10.
The rotor housing 70 inclu~les a plurality of ports 74 which pass 15 through the cylindrical wall 72. For reasons expl.,i.,ed in more detail below, the ports are desirably spaced equiangularly about the circu-"rerence of the housing. The rotor 50 is desirably positioned generally toward the distal end 78 of the housing, as shown in Figure 2. In a particularly p,ere~ d e",bodin,ent, the ports 74 are positioned about the wall 72 of the housing 20 immediately distally behind the rotor 50.
When the rotor is rotated within a blood vessel, the blood therein will tend to be thrusted gene,d;ly proximally by the rotor, as noted above. This creates a pressure dirrt:re,-tial between the area immediately forward of the rotor and that immediately behind the rotor, with the pressure behind the 25 rotor being significantly greater than that i-.,n~e.lia~ely in front of the rotor.
This increased pressure behind the rotor increases the pressure within the housing, and blood is therefore ejected through the ports 74. As the ports are positioned about the cylindrical wall slightly behind the rotor, the blood passing therethrough exit the housing 70 relatively close to the distal end 78 30 of the housing. The low pressure adiacent the distal end of the rotor tends to draw the blood bein~ expelled through the ports back through the rotor, wo gsnls76 2 2 6 d~ s al776 thereby creating a recirculating vortex wl,er~;n a sul,sl~nlial pollion of th fluid exiting through the ports tends to pass through the rotor fepeatedly.
When a Ill.c l.l~us is drawn into the housing by the rotor, the rotor will tend to divide it into a number of snlaller p2. lic!es, which may well remain 5 too large. However, these particles will be ~ ained in the blood expelled through the ports and will l~,erefore tend to be drawn back into the rotor and l,ecor..e ~legrade~ even further. After a surricicnt number of passes through this recirculating vortex, the lillo-llbus may be broken into a large number of very small, discrete pz. ~icles These ~a. ~;cles may be made small enough to 10 sul,sld"lially eliminate the risk that they would tend to cause blood to coagulate about them again to produce addilio,.al ll.ro,.lbi or cause any distale,~bol ~ation.
When in use, the rotor will usually be posilio~ed within the coi~li.,es of a VaSCtll-- channel adjace"l the location, or suspected location, of a 15 II.ruinl,us. When the rotor is roldted and causes b~ood to be ejacte.l through the ports 74, the ejected fluid will impinge upon the vascular wall, tending to urge the housing away from the vascular wall as a reaction to this impinging fluid. If each of the three or more equiangularly sp~ced ports are of substantially the same size, the fluid volume passing through each port and 20 the rate at which the fluid is expelled from the ports will be substantially equivalent. Accord- ~gly, the reaclio..a. y force acting against the housing to urge the housing away from the vascular wall will become equali7ed when each of the plurality of equiangularlv spaced, si",ila-ly sized ports are approximately the same distance away from the vascular wall. Thus, the 25 fluid flowing through the ports in the housing will tend to automatically center the housing and the rotor within the vascular channel when the rotor rotates.
If a force is appliEd to urge the housing away from its centered location, e.g., if the shaft 10 is deformed and begins to "whip," the force 30 associated with the blood being expelled through the ports will tend to rapidly urge the housing away from the vascular wall. Thus, the housing will not only aulu,.,atically be cenlered when in use, but it will tend to remain wo95/21576 ~ u~3~Jcl//6 -16- 2 f ~2864 cen~red within the vascular cl,an..el. If only two ports are utilized (as in thedevice shown in Figure 1), though, the housing may not remain cenlered.
The fluid e~e~led through the two Jia,.,t:l~ically o~posed ports will tend to ensure that the hous;ng remains equally spaced from portions of the vascular 5 wall along a line passing through both of the ports, i.e., in a horiconlal plane in Figure 1. However, if a force tends to urge the housing in a direction other than along that line (i.e., upwardly or downwardly in Figure 1), the fluid will not be expelled in a direction which would permit it to counteract this ~:ipl2ce..lenl and urge the housing lo~Jdrd the center of the vessel. Hence, 10 the use of three or more equiangularly space~l ports is prefe..~d due to its ability to cause the housing to remain ce.-~ered within the vascular channel.
Figure 12 shows a -.odificalio" of the ports shown in, e.g. Figure 3, which has been found to further o~ iCL the recirculation of the fluid flowing through the housing 70. As shown in Figure 3, the major axes P of the 15 generallv elliptical ports 74 in that e,l.l,odi...e-.l are generally parallel to the axis AH of the generdlly cyli.ld~ical wall 72 of the rotor housing.
In the e,-lt,oJi..,e,-~ illu~l,ated in Figure 12, though, the major axes P of the ports are disposed oblique to the axis A,~ of the housing. Although the major axes P of the el'irses are technically arcuate and wrap about the axis 20 AH Of the housing, the degree of offset between the generally parallel axes Pof the ports can be ex~,ressed as an angle a, as shown. An angle a of about 20 to about 45 has been found to help direct the fluid exiting the housing through the ports 74 toward the distal end of the housing, making the recirculating vortex of fluid more efficient and ensuring even more thorough 25 maceration of the thrombi e.,lrai.,ed therein in the same amount of time.
Figure 13 illustrates an alternative embodiment of the invention which utilizes a multi-stage rotor design. In Figure 13, the single rotor 50 of the embodi..,ent:, discussed above is replaced with a series of individual rotors 50A, 50B and 50C. Each of these rotors may be sl~aped generally as 30 outlined above and are each attached to the same shaft 10 for rotation therewith. The housing 270 of this embodiment ;s elongated to accommodate all three rotors. Although the housing 270 may be formed WO 95/21576 . ~ 6 -17- 2 1 ~2Q6~
entirely of metal or the like, having such an elongated, tigid housing may impair the ability to guide the rotors to a site in a patient's vascular system which may require following a tortuous path. Hence, in the ~ bod;r.,enl - shown, the elongate, generally cylindrical wall 272 of the housing 270 is 5 o~lilll~"y for".6~1 of a flexible n~at~,ial, such as a polymeric ",at~rial co."...G"ly used in forming call,eler~. In particular, the embodiment of Figure 13 utilizes a distal segn,enl of the casing 20 - which may be a call,et~r, as noted above - as the wall 272 of the housing.
In order to ensure that the rotors 50A-50C do not impinge directly 10 agairal the relatively soft wall 272 and to make sure that the rotors are properly cenle~.l in the housing, each rotor may be provided with a separdle sub-housing 280A-280C which 6nclGses the rotor. Each sub-housing 280 includes a ge..erall~ cylindrical wall 282, which may be f~,r",eJ of metal or the like, received within the more flexible wall 272 of the main housing 270.
15 ThTs wall 282 of the sub-housing is optimally ada~,ted to fit relatively snugly within the lumen of the main wall 272 to limit relative movement of these walls.
Each sub-housing also includes a forward strut 284 and a rearward strut 286, with each strut havin~ a rotaliG,~ sleeve 288 for rolal~tl~ receiving20 the shaft 10 ~I,e.~ll,rough. These struts serve to provide structural supportto the sub-housings 280 and passing the shaft 10 through the sleeves 288 in these struts serves to fix the relative posilions of the sub-housings and the shaft. Furthermore, since the rotors 50A-50C are affixed to the shaft, the sleeves 288 also serve to position the rotor within the sub-housing 25 assemblies, both centering the rotor within the circu,--ference of the wall 282 and preventing any undue axial movement of the rotors within the sub-housings.
As with the single-rotor design described above, the first rotor 50A can simply draw fluid in through the distal end of the housing. If so desired, only - 30 a single set of exhaust ports 274 may be provided adjacent the distal end of the housing 270. These exhaust ports 274 are desirably spaced generally equiangularly about the circumference of the housing 270 and serve much WO 95/21576 1 ~ J' 3~1776 the same functions as the ports 74 in the embodiments outlined above, e.g.
as~i~li..g recirculation of the fluid past the rotors and helping to center the housing within a vessel.
In a particularly pr~r.e.l e-.lLodi,..ent, though, the sub-housings 280A-280C and their associ~ted rotors 50A-50C, respectively, may be thought of as effectively defining three se~a,dle "~ace.dlion zones. Exhaust ports 274 are positioned at the rea, ~drd end of each of these zones, i.e. at a IOCaliOil spaced slightly proximally of the ~ssoci?ted rotor. In the embodiment shown in Figure 13A, these exhaust ports 274 are posilioned rearwardly of the sub-housing 280 and need only extend through the cylindrical wall 272 of the main housing 270. A set of equiangularly spaced intake ports 276 is also provided for each of the two proximally spaced rotors, 50B and 50C, with the intake ports 276 being posiLion~d ~ene~
distally of the associate.l sub-housings 280B and 280C, respeoli~ely. In the 1 ~ embodiment shown, each set of exhaust ports 274 and each set of intake ports 276 comprises four equiangularly sp~ced ports, with the exhaust and intake ports being axially aligned so that one intake port will be positioned immediately distally of the adjacent exhaust ports.
The main path of fluid flow is sche,.,~Lically depicted by arrows in Figure 13A. In this embodiment of the invention, the distal rotor 50A will draw fluid into the housing 270 through the open distal end of the housing.
After the fluid passes over the first rotor, it will tend to exit the housing through the exhaust ports 274. A subslalllidl portion of the expelled fluid will then reenter the housing through the intake ports 276 for maceration by the second rotor, 50B while the remainder of the expelled fluid will be drawn back toward the distal end of the housing for another pass by the first rotor 50A. The fluid will once again exit the housing 270 through exhaust ports 274 positioned behind the sub-housing 280B and reenter the housing through intake ports 276 disposed in front of the third rotor 50C. Finally, fluid will exit the housing through the last set of exhaust ports 274 stationed proximally of the third sub-housing 280C.

wo ssnls76 rcrlusss/0l776 2i 82~64 By allowing the fluid to exit the housing and reent~r rather than simply being thrust proximally through the housing until it is exhausted through a single set of ports, one can establish three se~Jarale recirculating vortexes, with a portion of the fluid exiting each rotor being passed rearwardly for ,..aceralion by the next rotor and another portion of the fluid being recirculated back into either the distal end of the housing or the previous intake ports 276 for another pass over the same rotor.
If so desired, optional bulkheads 290 ~shown in phanl~,--, lines in Figure 13A) may be posilion~d between the rotors. These bulkheads may be relatively thin struts such as the struts 284, 286 of the sub-housing assemblies and be utilized simply to support the relatively flexible wall 272 ofthe main housing to prevent it from being inadv~ "lly drawn into one of the rotor housings 280B, 280C during operalion. All~rl.ali-~ely, the bulkheads may be present a larger surface area, e.g. generally disc-sl.aped bulkheads 15 having cenl-ally located openings through which the shaft may pass. Such wider bulkheads would tend to restrict the flow of fluid through the housing 270, thereby limiting the amount of fluid that flows directly from one rotor to the other within the lumen of the housing without exiting through the exhaust ports 276 and reintroduced through the intake ports 276. The 20 bulkheads, particularly in this embodiment, are ideally placed between adjacent sets of exhaust ports 274 and intake ports 276, as shown.
As best seen in Figures 5 and 8, the housing 70 may be provided with a generally inwardly extending distal bead 76 adjacent its distal end. This distal bead is desi,ably rounded to provide the housing with a rounded distal 25 end 78 for contacting tissue as the device is deployed within a vascular system. The distal bead may be formed on the housing by inwardly deforming a distal portion of the cylindrical wall to form an annular bead disposed within a distal segment of the housing. Two possible bead constructions are shown in Figure 5, which depicts one useful shape, and - 30 Figure 8, which shows an alternative embôdiment of such a bead. Such a rounded distal end 78 tends to be less traumatic than either the more blunt wo g~ S76 PcT/US9S/01776 distal end 78 shown in Figure 2 or an exrosed rotor 50 which is not surrounded by a housing, as is most co,-'-.,on in the prior art.
As noted above, this distal bead 76 is desirably ~enerally inwardly exl~..d;..~, though it may also extend outwardly of the cylindrical wall 72 of 5 the housing. The inner diameter of the housing a~Jjacent its distal end, i.e., adjacent the distal bead 76, is desirably less than the ,.a~ -um outer ,Jia..,t:ler of the rotor 50. This serves as a further safety measure in that ifthe shaft 10 breaks, the rotor will be unable to pass through the distal end of the housing. This prevents the rotor and a broken off distal portion of the 10 shaft from l~ecG".i-~g left within the blood stream of the paffent if the shaft does indeed fail.
Figure 16 shows an aller--ali~e e..l~odi",e,-l of a distal end 78 of a housing for use with the invention. In the embodiments discusse~
illlllle~lidlely above, the housing was provided with a rounded tip by means of 15 a distal bead 76 ~on~ed integrally with the housing. In Figure 16, though, the distal bead 76' is formed of a relatively soft polymeric ."aterial, such as by molding the bead from a plastic cG~ llol~ly used in fu.., ~9 catheters and the like. The distal end of the cylindrical wall 72 of the housing desirably tapers inwardly to form a restrictive flange 75, to which the distal bead 76' 20 may be attached. This flange 75 desirably extends inwardly sufficiently to ensure that the distal end of the housing has a smaller diameter than the diameter of the rotor 50 to ensure that the rotor will be retained within the housing in the case of a broken shaft or the like.
Figure 8 depicts an alternative construction of a housing 70 for use in 25 the invention. In the embodiment shown in Figures 3A and B and Figure 5, the housing is desirably integrally formed of a single, unitary piece of material, such as surgical stainless steel. In the embodiment shown in Figure 8. however, the housing 70 is formed of two separate elements which can be affixed to one another when assembling the invention. The cylindrical 30 wall 72 which is carried about the rotor forms a first, distal element which can be permanently attached to the other, proximal segment 90 by any suitable means, such as by brazing. The proxi"~al segment 90 has a central WO 95/21576 PC~IUS95/01776 -21- ~1~2~64 aperture 92 extending ce~ ally therell-rough for rol~tdlJly receiving the shaft 10 to position a pfo,~i",al portion of the shaft and the rotor attached lt,~retuin the center of the cylindrical distal segment 72.
A plurality of fins 79 (desoriLed in more detail below) are positioned 5 equiangularly about a generally frustoconical housing insert 94. The insert 94 and the fins are sized to be closely received within the confines of the cyli.~J,ical wall 72 when the housing is assembled. The insert desirably tapers radially outwardly in a proximal d;reclion from an initial outer Jia,.,eter only slightly greater than that of the shaft 10 to an outer dia--,eler adjacent 10 its proximal end Jenerdlly equal to the inner diameter of the cyli..d,ical wall 72. Although this taper may be generally linear, in the pref~rred e~ol,odi..~entshown the rate of taper is much greater adjace,~l its proximal end. This directs fluid being thrust proximally through the housing radially outwardly through the ports 74, reducing the te,~lency of fluid exiting the housing to flow in a proximal direction, so that the fluid may be drawn back into the recirculating vortex explained above.
An annular abutment 96 may be provided adjacent the proximal end of the housing insert 94. This abutment has an outer diameter greater than the inner diameter of the cylindrical wall 72 and thus serves to abut the proximal end of the wall when the housing is assemtl!e~ If so desir~d, the wall 72 may be affixed directly to this abutment. In a particularly pref~-,ed embodiment, the outer dia-"eter of the abutment 96 is suL,s~"Lially equal to that of the cylindrical wall to provide the housing with a smooth outer surface.
As noted above, the housing insert 94 may include a plurality of fins 79 positioned equiangularly about its circumference. The number of fins employed is desirably equal to the number of ports 74 in the housing, and one fin may be positioned immediately adjacent each port. If so desired, the fins may be parallel to the major axis of their respective, generally ellipticalports. When the device is assembled, the rotor 50 will be positioned distally of the housing insert 94; the fins will therefore be positioned proximally of the rotor. As fluid is thrust proximally within the housing 70 by the rotor, it wo 9512ls76 P~ 3'~ //6 -22- 21 ~2864 must pass over the fins before exiting the housing. Any solid matter, such as a thrombus, entrained within the fluid will strike the fins, which form a part of the housing and are thus stationary with respect to the spinning rotor.
Solid matter will tend to be broken up when it impacts the fins, so the fins 5 serve to speed up the des~.addlion of thrombi or the like within the fluid.
A connector 80 may extend proximally of the cylindrical wall 72 of the rotor housing 70 and permit the housing to be attached to the distal end of the shaft casing 20. The connector 80 includes a first seg-,-e-~l 82 adjacent and connected to the cyli..J~ical wall 72 of the housing. The outer diameter 10 of this first seg,-,e.-t 82 is de:,;.dbly suLsldnlially equal to the inner diameter of the outer sleeve 22 of the shaft casing adjacent its distal end so the first s6ylllel~ 82 may be closely received within and retained by a distal portion of the outer sleeve 22. The outer Jian~ler of the cyl;.~d~;cal wall 72 of the housing is des;r;Jbly subsla~llially equal to the outer diameter of the shaft 15 casing 20 to ,orese.~t a relatively smooth outer surface at the junction between the housing and the shaft casing. The decrease in diameter between the cylil-d~ical wall 72 and the first segment 82 may be relatively abrupt, defining a generally rearwardly facing annular shoulder 84 for abutting the distal end of the outer sleeve 22. In order to ensure that the 20 housing is firmly affixed to the shaft casing, the first segment 82 may be cemented to the lumen of the outer sleeve by means of an epoxy or the like ~not shown~.
The connector 80 may also include a second segment 86 which is disposed proximally of the first segment 82 and is attached thereto. The 25 maximum dimension of this second segment is desirably larger than the inner dia"~eler of the inner bearing 26. The second segment thus serves to distally limit the axial movement of the inner bearing and serves to retain the bearing in place about the shaft 10 within the outer sleeve 22.
In a particularly preferred embodiment, the second segment 86 is 30 generally rectangular in cross section, as indicated in Figures 3A and B, rather than being generally cylindrical. The second segment may be substantially solid in cross section, but includes a central aperture passing therethrough for WO 95t:t1576 ~ 3a~ 776 2 1 82.~64 -2~-receiving the shaft 10. The axis of this cylindrical aperture is preferably subsl~r.lially ali~-.ed with the axis of the shaft and the aperture is sized to permit the shaft to freely rotate therein. The second sey-~el~t thus serves to support the shaft in a spaced rek,lionship with respect to the shaft casing 20 5 and helps to ensure that the rotor is axially centert:d within the cylindricalwall of the housing rather than abuffing against the wall. Utilizing a generallyrectangularly sl-aped seco,~d se~...ent having maximum d;.--e.~sions less than the dia-"eler of the first segment 82 provides a space between the second sey~lleill and the shaft casing 20. This space allows fluids, such as the 10 contrast mediums or riLfi-~olytic solutions noted above, to pass distally from within the casing through the housing and into the vascular channel.
Figure 10 depicts an alternative embodiment of a rotor housing 70 and con~e.;tor 80 for use in the invention. In this embo~li.nent, the connector does not include a second seg.~-el~t 86 ~ rosed rearwardly of the first 15 section 82. Instead, a coiled support member 86' is utilized. The support -,e,nber 86' is carried within the first sey,..enl 82 and extends along the length thereof from a position adjacent the annular shoulder 84 to the proximal end of the first segment. The support member d~si,aLly co...prises a widely spaced helical coil formed of a wire having a diameter adapted to 20 extend radially inwardly of the first se~."ent a sufficient distance to provide lateral support to the shaft 10 carried within the helical coil. The axes of theshaft, the first segment and the helical support member 86' are .lesirably substantially aligned with one another.
Adjacent turns of the helically coiled wire are desirably spaced apart 25 from one another. This pe-",its fluid to pass through the support member 86' at relatively high flow rates as the space between the adjacent turns effectively defines a generally helical path along which fluid may freely flow between the interior of the shaft casing 20 and the rotor housing 70. The direction of this fluid flow is schematically represented by arrows in Figure 1030 and, as indicated by the bi-directional character of these arrows, fluid may flow in either direction along this helical channel - if one is aspirating fluidfrom within the vascular channel, the fluid would flow generally proximally, wo ss/2ls76 P~ 95J~1 / ,6 -24- 21 ~28h4 while fluid would flow generaliy distally if one were delivering a lil"i-~olyticsolution or the like into the vessel through the shaft casing.
Figures 22A and 22B illustrate yet another embo.li.-le--t of the housing 70 and connector 80 of the invention. In this embo-3;--,e,-t, the first section 82' is adapted to be directly connected to the l,ea-ing 26 (not shown in Figure 22) within the casing 20. The first section 82' has a generally helical slot 83 extending about its surface. This slot 83 should be ada~ l to receive a distal portion of the bearing, which is dasird~ly a helically would coil, as noted above. The pitch of the coil should be adapted to permit the coil to be readily II-rea-led into the helical slot 83 in the cof)nector 80. If so desired, the bearing 26 can then be affixed to the connector 80, such as by brazing the coil to the connector or connecting these ~le",~ with a suitable adhesive. When asse,nbled, this co",-~clion between the bearing and the cor,nector may have an appea.ance substantially as shown in Figure 14 and desclil)ed above in connection with that drawing.
The connector 80 of the housing is desirably also provided with a shaft support sleeve 88 for supportingly receiving a portion of the shaft adjacent its distal end. The support sleeve 88 may be of any desired construction, but ,or~fe(ably comprises a thin-walled stainless steel tube, known in the art as a "hypotube," having a length of be~ ee.~ about 6.35 and about 8.89 mm (about 0.25 and about 0.35 inches~. The sleeve is sized to permit the shaft to rotate freely therein, yet limit lateral movement of the shaft so that it maystabilize the shaft in a position v~l.ere;,) the axis of its distal portion is substantially aligned with the axis AH of the housing. The support sleeve 88 may extend distally through the first 82 and second 86 segments of the housing (or the first sey".ent 82 and the support member 86' in the embodiment of Figure 10) to a position within the rotor housing 70 immediately adjacent the rotor 50 (as best seen in Figures 2 and 10).
Figures 17-19 illustrate embodiments of the invention which utilize fluid directing means to direct fluid exiting through the exhaust ports 74 back toward the distal end of the housing for further maceration. This serves to further ensure that fluid will be efficiently recirculated toward the distal end wo ssnls76 1~ .3e~l776 -25~ 2 8 6 4 of the housing to ensure that any thrombi present are thoroughly .,~acerdled.
The fluid cli~ecling means is optimally expandable from a collallsed state useful for deployment of the invention in a patient's vascular system to an expanded position wherein it is dir~l;li"~ fluid for recirculation.
In the ~ od;,.,ent of Figures 17A and 17B, a ball~D.) serves as the fluid di-e~;ling means. The casing 220 of this invention provides a selectively inflatable balloon 222 about a distal s~c~ion 224 of the casing. This "balloon call,eter" includes a separate inflation lumen 226 through which an ;~l~6liol-fluid may be p~sse~l and ports 228 deliver fluid from the i~ tldlio.. lumen 226 10 to the interior of the t?"~on 222 to inflate the balloon. The ba'~D.- may also be deflated in mush the same fashion, with the fluid being withdrawn from the interior of the balloon through the inflation lumen 226 via the ports 228.
Such "balloon o~ll,etb. j" are well known in the art and need not be ~iscl~ssed at great length here.
In using such an a"lbouli",eot of the present invention, the device will be positioned in a pd~i~r,l's vascular system at the desired location for tred~-.,e-lt. The balloon can then be inflated until it engages the sidewall of the vessel, subsl~nliall~ filling the lumen of the vessel. The balloon may be inflated with any suitable fluid which may be s~lhse~luently withdrawn to 20 deflate the balloon so that the device can be withdrawn when the operation is complete. It is particularly desirable to use a fluid which is bioco,n~alil~le, e.g. a radiopaque conlrast medium or a saline solution, so that no harm will be done to the patient if the balloon accidently ruptures.
The inrl~led balloon 222 serves two functions. First, fluid will be 25 effectively prevented from travelling proximally beyond the balloon. As the fluid is ejected from the exhaust port or ports 74 it will be readily drawn backup to the distal end of the housing for another pass over the rotor, promoting the recirculation of the fluid to thoroughly degrade any thrombi entrained in the fluid. This can be particularly helpful in situations where the risk of 30 serious consequences arising from even relatively small llllol-lbi being left after the procedure is higher than normal, as in cardiac or cerebral appl ~alions. Second, the inflated balloon 222 will help to center the housing wossms76 P~ 17I6 2 1 ~3286~

in a larger vessel to reduce the likelihood that the vessel wall will be injuredby the rotor in any way. Although this may not be necessary in a,~ licaLiG"s where the housing has a pluralitv of equiangularly spaced exhaust ports 74 because these ports will tend to make the device self-centering, as detailed 5 above, this can be useful if such ports are not employed, as in the self-steering and self-pumping e,--bo~ ents ~liscussed below.
Figures 18 and 19 provide alternative fluid directing means for providing ~rficie~t recirculabon of fluid in much the same manner as the balloon 222 of Figure 17. In the embodiment of Figure 18, the fluid directing means comprises a flexible sheath 240 which e3~ -.1s about a distal portion of the casing 20 and a proximal portion of the housing 70. This sheath 240 is desirably r~----ed of a relatively flexible elastomeric ".al~-ial, such as a latex .-,aterial such as that c~-n-..ol)ly used in the l,alloGns of balloon catheters or the like. The sheath 240 should be adapted to be carried along the housing 15 70 and the casing 20; optimally, the sheath is sized so that it will fairly snugly engage the outer surfaces of these ele-,.enls.
The sheath 240 should be attached to the casing 20 at a point proximal of the exhaust ports 74 and extend distally to suLslanlially cover these ports. When the rotor (not shown) is not in operation, the sheath will 20 lie against the ports and may subsla.,l;ally seal the ports. When the rotor is engaged, though, it will tend to thrust fluid out of the exhaust ports, as notedabove. The force of the fluid exiting these ports will tend to inflate the sheath 240. Since the sheath is fixed adjacent its proximal end to the casing 20, the distal end of the sheath will be more inflated than the proximal end, 25 yielding a generally frustoconical structure as shown in Figure 18. As shown schelllalicall~ by the arrows in this drawing, this will tend to direct the fluid exiting the ports back toward the distal end of the housing for another pass through the rotor.
The fluid directing means of Figure 19 co.~,prises a plurality of normally 30 closed gates 250. The operation of these gates is similar to that of the sheath 240 of Figure 18. Desirably, one gate 250 is associaled with each exhaust port 7~ of the housing. The gates are hingedly connected to either wo ssms76 PcTnJsss/0l776 -27- 2l 1~64 the housing 70 or the casing 20 at a location disposed proximally of the ports 74. The gates 250 are biased toward a closed position wherein they engage the housing to generally cover the ports 74 by any suitable means, such as with a leaf spring or the like. As with the sheath 240 of Figure 18, when the 5 rotor is engaged, the fluid being expelled from the houslng through the ports 74 will urge the gates away from the housing and the gates will tend to redirecl the fluid distally for recirculation.
If so des;~:d, the fluid dileL~in~ means could be relatively rigid and always be in he configuration used to redirect fluid distally for recirculation.10 However, that may lead to some problems in deployment; deployment of the device of Figure 19 in a patient's vascular sysl~.n could be hampered if the gates 250 were to remain in the position shown in the drawing. Although it is ll.e(efore ~rer~ .l that the fluid directing means be s~l~cli~ely configurable between a relatively compact deployment configuration and an 15 expanded configuration for redirection of fluid, it is to be understood that a permanent structure could instead be employed.
In the embodiments ~iscussed above, the housing 70 generally includes a plurality of generally equiangularly spaced exhaust ports 74 which serve to substantially center the housing within a vessel when the rotor is 20 rotated. As detailed above, this has some distinct advantages. Figure 20, though, illustrates a clitrerent embodiment which utilizes only one exhaust por~ 74 In the embodiment of Figures 20A and 20B, a single exhaust port 74 is provided in the housing 70 and this port preferably extends about no more 25 than about 50% of the circ~""rerence of the housing, and desirably extends about sub~ld"lially less than ~0% of the housing's circumference. As explained above, rotation of the rotor will cause fluid to flow rearwardly, whereupon it is expelled through the single exhaust port 74. This will tend to deflect the housing toward one side of the vessel. Although this may not be - 30 as desirabie as having the housing centered within the vessel, as is the housing of the embodi",enl~i described above, during maceration of thrombi, WO 95121576 P~ 1776 2 1 ~2864 this directional urging of the distal sey..,el~t of the device can be used to help deploy the device within a palienl's vascular system.
When deploying a device of the earlier e,.lbG(li.~e,l~ of the invention, a guidewire will generally be guided to a desired locatio,. within the vascular 5 system by observing progress of the guidewire on a fluorosco~e of the like and posilioriin~ the distal end of the guidewire adjacent an iJe"li~ied ll,r~-"bus in the vascular system. The device of the invention will generally follow the guidewire, as explained above, so that it can be posiffoned for lr~dl-,~ent. Generally, the rotor will not be r~latad by the drive means until 10 the housing is in the selected posilion for l-edli"g the patient.
By utilizing a single port 74 as shown in Figures 20A and 20B, though, the need for a guidewire can be eliminated. The device can be urged distally within the palit:,.l's vascular system. When the vessel branches and the operator must direct the device into one branch, for exa..,ple, the rotor can be activated. This will cause the distal end of the device to be bent generally toward one wall of the vessel. By turning the device, and hence the housing 70, the direction in which the distal end of the device is bent with respect to the vascular channel can be altered as desired. Once the distal end of the housing is oriented toward the clesirecl path, the device can once again be urged distally to move the housing into the desired branch. If so desired, the rotor can be then deactivated until it is need to orient the device toward a particular path. This process can be repeated as necessary until the desired l-eal",enl site is reached, whereupon the thrombus can be macerat~d by the rotor as explained in some detail above.
Utilizing a single port as shown in Figures 20A and 20B consequently permits an operator to steer the device within a patient's vascular system without need of a guidewire or the like. Not only can this self-steering feature potentially simplify the deployment process by eli.,~inali"g the need toseparately introduce and deploy a guidewire, this can also reduce the overall dia",eter of the device by el;minating the need for additional structure to track the guidewire, such as guidewire tracking channels 28 and 28'. This wo~snls76 Pcr/u~ 3S~1//6 -29- ~182864 reduction in diameter can permit the device to be used in smaller vessels which may otherwise be unreachable.
~igure 22 also illus~-a~es an alternative housing design which perl.,il~, the device to be steered during deployment by ro~,~ling the rotor. In this 5 housing design, three or more exhaust ports 74, 75 are provided on the housing 70 for discl-argi-~g fluid through the wall 72 of the housing when the rotor is ruldl{:d. These ports 74, 75 are desi~ably spaced generally equiangularly about the housing, as in the embodiments detailed above. Any suitable number of ports may be used; in the embodiment shown in Figures 10 22A and 22B, three ports are used, with each port being spaced from the other by about 120.
Providing three or more generally equally sized ports spaced equiangularly about the housing will tend to produce a self-ce.~te-i-,~3 effect when the rotor is rotated by the drive means 100. In the enlbodiment of 15 Figures 22, though, the two ports identified by reference number 74 are s~lLs~ar,lially the same size, but a third port 75 is subsl~ntially smaller thanthe main discharge ports. When the rotor is rotated, more fluid will tend to exit the two larger ports 74 than will exit the smaller port 75, which will in turn tend to deflect the housing in the dire-,lion of the side bearing the 20 smaller port. It has been found that by n,~ g the surface area of the smaller port 75 about 20% that of either of the larger ports 74 will yield suitable steerability to the housing upon rotation of the rotor.
It should be understood that the present embodiment of the invention need not use only three ports nor have a single port smaller than the other 25 ports in order to achieve similar self-steering properties. For example, fourports can be used, with two of the ports being smaller than the other two ports, which would induce the housing to deflect in a direction between the two smaller ports. Alternatively, one could provide a housing with a plurality of ports which are all the same size but are not spaced equiangularly about 30 the circumference of the housing, which would also tend to deflect the housing when the rotor is driven. So long as the fluid passing through the ports which produces a deflecting force, whether by a difference in the wossnl~76 ~ 9~ 7~6 volumes of fluid passing through the ports or by unevenly spacing the ports about the housing, this principle can be used to produce a self~sle~rdble housing which can be advanced into position within a patient's vascular system subsla.~lially as .l~sc~il,ed above in connection with Figures 20A and 5 20B.
As explained above and in the examples below, the device of the invention is quite effective at macerating clots and the like and only a rather small fraction of the clot will remain over about 100 ".:~rons in size. In certain applicaliG,)s, though, (e.g. use to degrade thrombi in cardiac and 10 cereb(al vessels) it may be ad~vdl~ldgeous to remove even such small volumes of over~i~eJ particles. As noted above, most prior art devices utilize as~.irdlion to suction off fluid during operation of a Ll.ron.Lectomy or ather~clo,..y device to remove unwanted clot. The ge~eral!y rear~rlard thrust of the present rotor, though, can be employed to effectively pump fluid 15 rearwardly for disposal outside of the patient's blood without any requiring any sepa.ate as~--.alion equipn.e.,l.
In order to achieve this end, the fluid which passes through the rotor should not be permitted to exit the housing for recirculation, but should instead be retained within the housing 70 and the casing 20. Figure 21 20 illustrates one particularly pref~rred embodiment of a self-pumping maceration . ,~ . .
device of the invention. As shown in that figure, the housing 70, which may be located at the distal end of the casing 320, does not include any exhaust ports. Instead, all of the fluid entering the distai end of the housing will be retained within the device and thrust generally rearwardly by rotation of the 25 rotor.
As explained above, e.g. in connection with Figure 4, the rotor of this embodiment of the invention is desirably a "screw type" rotor having two or more generally helical blades 56 which are oriented at an angle with respect to the main shaft of the rotor. Since the rotor is enclosed within a sealed 30 housing, such a rotor will effectively serve as a positive displacement pump and will urge the fluid drawn into the housing rearwardly and out of the proximal end of the casing. Although the volume of the lisplacement of the WO 95/2I~i76 l ~ J.,,SJ~1776 -31- 2l~2864 rotor for each turn is relatively small, when the rotor is Gpe,aleLI at relatively high speeds ~such as the 100,000-135,000 rpm which is dee~ned to be o~li,nal), the net volume of fluid being displaced may be sL,~ricient to ensure that the .~.ace~att ~l lhro-nLi are pumped proximally out of the pdlienl's 5 system.
In some circu...slances, though, the pressure of fluid within the casing may be too high to efficiently pump the fluid out of the ~udlielll's vascular system. In such a circumslance, it may be desirable to include a second rotor to effectively boost the rearward thrust of the first rotor to expel fluid10 proximally out of the casing. Figure 21 illual-dtes one embodiment of such a device in accorda.~ce with the invention.
In Figure 21, a second rotor 350 is disposcd proximally of the primary n.acerdlion rotor 50. This second rotor is desi-a~ly affixed to the same shaft 10 as the forward rotor 50 so that both rotors will rotate lo~ell-er. The rotor 350 is carried within a sub-housing 370 having a gane-dlly cylindrical wall adapted to fit within the lumen of the casing 320 and a pair of end struts 374, 376 for providing structural support to the sub-housing. This sub-housing 370 is directly analogous to the sub-housings 280 of the multi-stage maceration emboclin-e,)t shown in Figures 13A and 13B.
The forward rotor will tend to ,.. acerale thrombi and degrade any fibrin in the thrombi to yield a more homogenous, flowable fluid, so the second rotor 350 need not perform any great deal of maceration. Instead, the primary purpose of the second rotor 350 is to serve as a booster to assist in the pumping of the fluid. Although only a single booster rotor 350 is shown 25 in Figure 21, it is to be understood that any number of rotors can be spaced along the length of the casing to achieve the necessary flow of fluid therethrough .
Although both of the rotors may be of about the same size, the proximal booster rotor 350 of Figure 21 is substantially larger than the - 30 forward rotor 50. This permits the booster rotor to displace even more fluid at the same rotational speed, thereby enhancing the pumping action of the device. This booster rotor 350 is desirably spaced a considerable distance WO 95121576 P-,llU~ .)S1~,1776 2 ~ ~2~64 proximally of the forward rotor 50. This will permit the forward housing 70 to be guided into relatively small vessels, e.g. for lfsdl."enl of ll-ro--,bi incardiac and cerebral vessels, while the booster rotor can remain in a larger vessel.
In order to acco,~ Gdale the larger secoi~d housing 370 yet fit snugly againil the forward housing 70, the casing 320 of this invention opli--.ally has a smaller dia,..el~r at its distal end ~djacent the first housing 70 and a relatively large dic~ ler along a proximal length 324. In the particularly prere..ed emboJi..-e-,l shown in Figure 21, the casing has an alongale distal segl-,ent 322 having a first diameter, an elongate proximal sey--,ei,l 324 having a second, larger diameter and a lc-pered segment 326 disposed between the distal 322 and prokin~al 324 segments. This tapered portion eliminates any sharp discG--~ uities in the flexibility and other mechanical properties of the casing 320 to minimize any problems in deployment.
The relative lengths of the distal, proximal and tapered seg-"e~ may be varied as desired for specific applications. In one prererred embodiment, the distal segment is about 10 cm to about 30 cm in length with an outer dia",eler of about 5.0 French ~about 1.67 mm) and the tapered segment tapers relatively gradually from this 5.0 French distal sey-.-ent to a 8.0 French (about 2.7 mm) diameter proximal segment over a length of about 10 cm to about 25 cm. The proximal seg,--e-,L can be of any des;rell length which per~ i the distal end of the housing to be positioned at the desired treatment location within a patient's vascular system; a length of between about 50 cm and about 80 cm should work well.
The present invention also includes a drive means 100 for rotating the shaft 10 within the shaft casing 20 to cause the rotor 50 to rotate. Any suitable drive means may be used, but it is preferred that the drive means be capable of rapidly rotating the shaft and the rotor. As noted above, a rotor of the invention is desirably rotated at speeds between about 80,000 and about 150,000 rpm, with an operating range of between about 100,000-135,000 rpm being preferred.

~RCI~I FORRESTERS LONDON 5. li'. 1996 13: 18 P. 12 . . ~ . .
., ,. -.
2 t 82864 Although the d~ive muans may b~ o~ any typQ which wlll rotate the sh~ 10 and rotor 50 at ~ho de~ired speed, such a~ a high-~pee~ elec~ric motor, ln ~ proferrcd embodiment an alr-driven turbine i~ employed. As ohown in ~igure~ 1 and 7, this ~rlv~ meanC include~ a hou~ng 102 having f lr~t and 88COn~ ~ection5 (104 an~ 106 respectively~. The fir~t ana cecond ~ectlons 104, 106 are adapted to be 6ealingly afflxed to one another to d~flne a ~hort, ~u~stantially alr-tight cylinder. The ~ir~t ~sction 104 de~rAbly compri6e6 a ~ubstantially ~l~t, clrcular In thc em~odlment of Figure 1, the ~econd ocotlon 106 comprises a generally ~lat, circular dl6tal face llo and a per~pheral wall 1~8 ex~ends generally perpendlou~ar laterally from thi~ ~ace 110. The dl~meter of th~ firat cection 104 of the hou~ing ls gr~a~er than the ~ nner diameter o~ ~he perlpheral wall 108 ~nd ~y be ~ub~tantially egual to the outer dlameter o~ that w~ll.
Although the hoU~ing may b~ ~ormed o~ ~ny euitabl~
~aterial, in the pre~erre~ embodlmenl i~ is for~d o~ ~
polymeric ~aterlal, 8UC~ as a high density, ~a~hln~blo pla~tic, which ~ay ~e ~onically wel~ed to permit th~ fir6t and second ~ectlon~ ~04, 106 to be secllngly a~f~xed ~o one ~nothcr wlth ~as~.

A~ deplcted ln Figure 1, an ~ir inlet 120 ana an air outle~ 134 may ~e provided in an~ ext~n~ radlally ou~wardly through the perlph~ral wall 108. ~h~ a1r ~nlot include~ an ~nlet tube 124 which extends through the inlot port 122 in t~e hou~lng and i~ adapt~d ~or ~tt~chmont to ~n air ~upply. In most opQrat1ng theaters, ~ pressur~zod ~ir ~upply 18 provid~d, Wlth pre~ur~s usually in ~h~ rang~ o~

~a~e~t FR3~1 FORRcSTERS LONDCIN 5. 17. 1996 1~ 8 P. I:S

~1 ~2~64~

- 33a -about 241.3 KNm~ ~o about 344.8 KNm3 (about 35 to about 50 p~1). The lnl~t tube ls prefer~bly configurQd to b~
16eal1ngly ~eceived within and reta~ n~ at one end or a lengtll o~ flexible hosing (not ~hown), the other end o~
whlch may be operatively attached to the pre~urlzed air supply to direct pressurlzed air to the drlve means 100 through the ~nlst tu~e 124.

As noted above, the dri~e means 100 desl~bly ~l~o lncludes ~n air o~tlet 134. This alr outlet allow~ air to e~cape the hous~ng 102 ~o that a continuou ~low of ~r may flow into the hou~ing t~rough the air inlet 120. The alr outlet 134 ~ay be positloned substantially anywhere on ~le hou~ ing .

~AN~ED S~

... , . _ wo ssnls~6 P~nJ~S~17I6 -34~ ~ l ~2864 In the e."bodi."enl shown in Figure 1, though, the air outlet comprises a port which extends radially outwardly through the peripheral wall ~08. In a particularly preferred embodiment, the air outlet 134 is positioned about the circumference of the peripheral wall relativeiy close to the air inlet in a 5 direction opposite the direction of flow of air within the housing (generally clockwise in Figure 1). In this manner, air ent~ri-~a the housing through the inlet 120 is forced to travel around most of the circu...t~ ..ce of the housing before it may exit through the air outlet, serving to more rapidly accelerale the turbine to full rotational speed. In one ~orerer.~tl embodiment, the air 10 outlet is provided with an outlet tube 138 carried exleally of the housing to direct the flow of air exiting the housing.
An alternative embodiment of a drive means 100 which has been found to work particularly well with embo~i---6,-ls of the pre~ent invention is shown in Figure 7. The construction of this drive means is similar to that described above for the embodiment of Figure 1. In particular, the housing 102 has a generally flat, circular first section 104 wh;ch is sealingly affixed to the second section 106 to define a short, substantially air-tight cylindricalhousing. Once again, this housing is desirably formed of a machinable polymeric n.dle-ial which may be sonically welded to sealingly affix the first and second sections 104, 106 to one another.
The positions of the air inlet 120 and air outlet 134 in this embodiment differ from those in the embodiment shown in Figure 1, though. In the present embodiment, both the air inlet and the air outlet pass through the first section 104 of the housing, i.e., at the housing's proximal end. The air inlet 120 includes an inlet port 122 which passes through the first section 104 of the housing and within which is retained an inlet tube 124. An air supply connector 126 may be provided for sealingly receiving an air supply, such as a length of flexible housing 123, in fluid communication with the inlet tube 124. At its distal end, the inlet tube 124 includes a terminal segment 130 which is positioned immediately adjacent the turbine 150, as explained in more detail below. A venturi segment 128 is provided in the inlet tube between the proximal end of the inlet tube and the terminal W0951~1576 r~ U~S~'~1776 -35- ~ a 6 4 seg."e..l 130. The venturi segment has a larger diameter at its proximal end than at its distal end where it is sealingly affixed to the terl--;nal segmenl. As is well known in the art, this relatively rapid drop in cross seclio,~al area along the venturi se~-,.enl will tend to accelerale the flow of fluid, i.e., air, as it 5 passes from the air supply to the terminal segment 130 of the inlet tube.
The axis of the inlet tube 124 is desirably sul,~.,liall~ aligned with the axis of the ge,)er~lly cylindrical housing 102 so that the te.,.~;nal se~.,-ent 130 othe inlet tube may be posilio,-6d centrally within the housing immediately adjacent the axis of the turbine 150, as explained below.
10As noted above, the air outlet 134 of the present e"-bodimenl desirably passes through the first section 104 of the housing 102. In this manner, air may be vented rearwardly out of the housing. In the prefer.~d e.,~otJi...enl shown, the air outlet 134 incl~des an outlet port 136 which e~.t~nds through the first secli~n 104 of the housing. In a particularly 15 prbr~.-eJ e,-lbGJi,--enl, a plurality of such outlet ports are ublized, the outlet ports being spaced equiangularly about the axis of the cylindrical housing with the axes (not shown) of the outlet ports 136 being generally parallel to and spaced radially outwardly from the axis of the housing. If so desired, a baffle means 140 may be provided in each outlet port 136 to diffuse the flow 20 of air out of the housing. In one prere..ed embodiment, the baffle means 140 comprises a generally porous, sponge-like material which dampens the flow of air, yet ~e..-,iLs air to pass ll-er~ll,rough.
The drive means 100 also includes a turbine 150 which may be caused to rotate by the flow of air through the inlet tube 124 of the air inlet. Any of25 a wide variety of suitable turbines may be utilized, but a preferred e~.bodi.I~e~lt of a turbine for use with the present invention is shown in Figures 7 and 9. This turbine 150 may be formed as two separate elements, i.e., a distal segment 152 and a proximal segment 154, which are joined together to produce the turbine after being independently formed. As best 30 seen in Figure 9, the distal segment 152 of the turbine is generally disk-shaped and includes a plurality of generally triangular, wedge-shaped upright proiections 156 spaced about its periphery. Opposing walls of WO 95121576 ~ 1776 -36- 21 ~286l~
adjacent projections are desi- dbly spaced apart from and generally parallel to one another to define an u~.riy~llly open channel 158 therebetween. The wedges and resulting channels are desirably spaced equiangularly about the periphery of the distal segn.e.~t 152.
The upright projections 156 desirably do not extend all the way to the center of the disk-shaped distal ses~--,e~, but rather extend inwardly from the periphery a specified dislal1ce, which may be on the order of one-half the radius of the distal se~...ent 152. This defines a generally circular central portion 160 which is bounded about its periphery by the inner edges of the upright projections 156. The channels 158 are desirably Grie"ted generally tangentially with respect to the periphery of this central portion 160 so that as air strikes the center of the turbine, as explained in more detail below, it will be urged tangentially o~ ly through the channels 158 and cause the turbine to spin. As also explained more fully below, the central portion 160 of the distal sey".el-l of the turbine is generally conical in shape and comes to a peak 162 generally along the axis of the disk-shaped distal segment. In a particularly preferred embodiment, the central portion 160 has a generally elliptical profile (as best seen in the cross sectional view of Figure 7) ratherthan having a substantially flat incline.
The proximal portion 154 of the turbine is also generally disk-shaped and desirably has an outer diameter substantially equal to that of the distal segn)e"l 152. The proximal segment generally includes a central portion 170 and a peripheral portion 169 extending radially outwardly of the central portion. The peripheral portion 169 includes a plurality of fingers 168 which extend generally tangentially outwardly of the central portion 170. These fingers are adapted to be matingly received within, and fill a portion of, the channels 158 in the distal segment 152. In a preferred embodiment, the fingers 168 are generally rectangular in cross section and extend generally downwardly in Figure 9 to define between adjacent fingers a generally triangular, wedge-shaped recess for matingly receiving the upward projections 156 of the distal segment. Although the depth of the fingers may WO 95121576 1 ~ U~3~'~,1776 _37_ 21~2864 be varied as desired, they desirably extend downwardly within the channels 158 to a depth of appro~ lately one-half the depth of the channel.
The distal and proximal ses~,ne.)ts 152, 154 are desirably formed of an injection moldable polymeric material which may be sonically welded. This permits the individual se~--,enls to be accurately and inexpensively produced by injection molding and l~e.,.,il~ the seg.-,e.~l~ to be l~e.-"aoently affixed to one another by the process of sonic welding. If so desired, a plurality of sacriricial nibs 166 may be spaced about the proximal and/or distal seyment~.
During the sonic wel~i"g process, these sac-iricial nibs will be broken down and will serve as a wel~".ent for securely attaching the proximal and distal segments to one another.
The central portion 170 of the proximal sey,l-e,-l 154 desirably inclu~es a centrally locdle~l, generally fru~loco"ical cap 174. When the turbine 150 is asse"~l~led, the cap will be spaced away from the central portion 160 of the distal se~.nent to define an airflow ch~."ber (175 in Fiç~ure 7) therebel~r oen. The cap includes a central port 176 through which a stream of air may pass and an up:,~dn.~ing lip 177 may be provided about this port. The thickness of the lip 177 may decrease proximally, as shown in Figure 7.
As best seen in Figure 7, when the drive means 100 is asse"ll,led, the axis of the turbine t50 sul,slal)~ially coincides with that of the housing 102 of the drive means and inlet tube 124 of the air inlet. The turbine is positioned immediately distally of the inlet tube. The upstanding lip 177 of the proximal segment 154 of the turbine is desirably positioned immediately adjacent the distal end of the terminal sey-"enl 130 of the inlet tube; if so desired, a short length of the lip 177 may even be rotatably positioned within the distal end of the terminal segment. This ensures that air flowing into the drive means through the inlet tube 124 will flow directly into the chamber 175 of the turbine. The air within this cl,d-,lber is forced out of the turbine - 30 through the tangentially oriented channels 158 of the distal segment, causing the turbine to spin about its axis. The air then flows into the rest of the WO 95/21576 P~ -lllJS95.'~17 ~6 -38- 21 8~64 housing 102 and exits rearwardly through the air outlet 134, as descril,ed above.
As noted above, the venturi segment 128 of the inlet tube serves to accele~d~e the flow of air through the tube. ~he air thus enters the chamber 5 175 at a rather high flow rate, which serves to relatively rapidly accelerale the turbine to its full rotational velocity. F~ I,er.,lore, by forrning the turbine of relatively light weight polymeric materials, the ,..Gmenl of inertia of the turbine will be reduced and the turbine may be accelerated even more rapidly.
In the e.nbodi",ent shown in Figure 7, the shaft 10 of the device is connected to the turbine 150 for rotation therewith by means of a drive coupling 180. The drive coupling may be attached to the turbine and the shaft by any suitable means. In the embG.limel,~ shown, the turbine includes a generally cylindrical drive coupling recess for .ecOiv;"g the tubular drive coupling 180 and the drive coupling may be fixed within this recess. The 1 5 drive coupling 180 desi.~bly also includes a central recess (not separatelyshown) within which the shaft ~0 may be received and within which the shaft may be affixed.
The drive means 100 desirably includes a distally extending, manually graspable sleeve 36, which may be formed integf~ / with the second section 106 of the housing. If so desired, the outer surface of this sleeve may be provided with a rougher texture ~as shown in Figure 1 J to permit the sleeve to be more readily and more securely grasped by an operator of the device. The sleeve 36 is desirably tubular in shape and is adapted to receive the drive coupling 180 and a proximal portion of the shaft 10 therewithin. In order to ensure that the axes of the drive coupling 180 and turbine 150 substantially coincide with that of the sleeve 36, bearings 184 may be utilized. In the embodiment shown, two sets of bearings are used, with one being carried adjacent the distal end of the drive coupling and the other being spaced proximally at a location adjacent the drive coupling recess 182 of the turbine.
Any suitable bearing may be used, but the bearing should permit the drive coupling 180 to freely rotate with respect to the sleeve 36 as the turbine and shaft are rotated.

WO gS/21S~6 PC~/US95101776 -39- 21 ~2864 ln the embodiment shown, the sleeve 36 is r~lo,.gale in shape and serves to encase structural elen~e~ . of the device in addition to the drive coupling 180 and bearings 184. In the embodiment shown, a spacer 188 is carried within the sleeve at a position i".".edidlely distally adjacent the drive 5 coupling 180. The spacer is generally tubular in shape and is adapted to be closely received within the sleeve 36. The spacer includes a central bore 190 extending through its length, the bore being sized to rotd~al.ly rece;ve both the shaft 10 and the inner bearing 26 previously desc,il,ed and support these ele...e,lL~ ye,.erdll~ celllf~lly along the axis of the sleeve. As noted above, the bearing 26 is not affixed to any other element of the device, including *e spacer 188, but rather is "free-floating.~ The spacer 188 may be affixed within the lumen of the sleeve 36.
In order to ensure a Sul~S~ dlly fluid-tight seal, an 0-ring 192 or the like may be positioned between the spacer and the inner wall of the sleeve.
This prevents the fluid used to drive the turbine, i.e., air, from entering the shaft casing 20 and flowing into the bloodsl-aa-,-. Also, it prevents fluids within the casing, such as blood or fluids which are delivered to the casing 20 through infusion line 30', from entering the housing 102 of the drive means. A portion of the spacer i-,l,-,ediately adjacent the attachment of the infusion line 30' to the sleeve 36 is desirably spaced away from the inner wall of the sleeve in order to permit fluid to pass from the infusion line into the casing as previously explained.
Although the outer sleeve 22 of the shaft casing may be affixed directly to the sleeve 36, in a preferred embodiment the outer sleeve is affixed to a swivel connector 194 retained by the sleeve. The swivel connector includes a body 196 which is retained within the lumen of the sleeve and a distal extension 195 which protrudes distally out of the sleeve through the sleeve's distal exit 38. In order to restrict the flow of fluid fromthe infusion line 30' so that it will only pass into the shaft casing 20, an 0-ring 196 may be disposed between the body 196 of the swivel connector and the sleeve 36. The swivel connector is desirably rotatable within the lumen of the sleeve, and a bushing 198 or the like may be utilized to ensure Wo ~5121576 PCTIUS9~101776 ~ 2 1 ~2864 that the swivel connector can rotate freely with respecl to the sleeve. The tubular distal e~cle~lsion 195 may extend forwardly of the sleeve, as noted above, and desirably is adapted to closely receive the outer sleeve 22 of the shaft casing therein. If so desired, the outer sleeve may extend along 5 subsla-,lially the entire length of the swivel connector. The outer sleeve 22 may be sealingly affixed to the swivel connector by any suitable means which will afford a generally fluid-tight seal between the swivel connector and the shaft casing 20.
By providing a drive means 100 such as that described above, a readily 10 available pressurized air supply may be utilized to rotate the shaft 10 and rotor 50 of the device. As noted above, the design of the preferred el..bodi.-.ent is configured to "a~dn-ice the acceleration of the shaft. It wasalso noted above that if the shaft is a~c~l3rated too slowly, there is a risk that fibrin co~ ned within a thrombus may become wrapped about the rotor rather than being broken into a number of pieces thereby. By providing a turbine which will rapidly accelerate the shaft from an initial stationary stateto its full rotational speed, this risk is minimized and sub:jtanlially all of the fibrin contained within a Ih-c"nl.us may be degraded into very small, discrete pieces.
A number of experiments have been carried out utilizing the invention described above. First, bench tests were pe, ror",eJ in vitro by first artificially producing Ll--o~ i and then breaking down the thrombi with the l,resenl invention. Human blood clots were produced by mixing packed red blood cells and whole plasma with calcium chloride and allowing the blood to clot and consolidate for a period of 7-10 days. This produces a clot with a moderate degree of fibrin conlent but not a great deal of calciricaliGIl. The clots so formed ranged in length from about 3 to about 10 cm and were between 1 cm and about 3 cm in clialneler. These artificially produced clots were then placed in test tubes and the distal end of a device according to the invention was placed within a test tube. Air was supplied to the drive means 100 to turn the rotor at between about 100,000 and about 13~,000 rpm.
The homogenized .naterial was then filtered through a series of nylon screens wo ss/21s76 P~ 9'/~l776 -41 - 2 1 ~ 2 8 6 4 having varying pore sizes. The first screen had a 200 micron pore size, the second was 100 ...icrons, the third was 47 microns, and the final screen had 13 micron pores.
It was found that by driving the rotor when it is positioned at or 5 aJjacen~ the site of the clot for a period of between t 5 and 45 seconds, clots could be sul3sldnlially cG,-")letely degraded into rather fine particles. The larger clots would generally require longer periods of time, such as 45 seconds, in order to be completely degraded, while smaller clots may be dey-dded in 15 sec6nds or less. As a result of this testing, it was found that 10 embodiments of the invention may readily degrade ll,ron,Li in less than a minute to a point wherein 99.76% by weight of the thrombus will pass through a 13 micron screen. Of the re,..ai~ing 1/4 of 1%, approxi~ ly 0.10% of the particles exceeded 200 microns, 0.03% were between 200 and 100 ,..icrons in size, 0.05% were between 100 and 47 n.:cro~s, and 0.8% of the particles, by weight, were between 47 and 13 microns in size.
As it is generally accepl~cl that pa.licle sizes less than about 90-100 microns do not pose any significant risk of forming additional thrombi if left within the blood~l,eam, these results indicate that the invention can degrade upwards of 99.8% of a thrombus to essenlially harrnlessly sized particles in less than a 20 minute.
Animal testing has also been conducted. Artificial blood clots were formed in mongrel dogs in a manner similar to that noted above. By Icnown techniques, a device in accordance with the invention was guided to a position wherein the rotor was adjacent the suspected location of such a clot 25 and the rotor was actuated by supplying air to the drive means 100. The dogs were then sacrificed and a series of tests were performed to determine the level of hemolysis ~rupturing of the red blood cells) and to ensure that no damage was done to the intima of the vessels. In none of these tests was any clinically significant degree of hemolysis or trauma to the vessel walls - 30 noted. Over 90% of the animals tested averaged 97% dissolution of the artificially created occlusive clot. As a ~succe.ssful" dissolution is generallydefined as improving vessel patency, i.e., widening the opening in the vessel, wo 9SI21576 PcT~s95101776 by 50%, these results indicate that the device is highly successful in degrddi.)g lll.ul-lbi within the vessels o~ a living n,a""~al without any appreciable degree of harm to the blood cells or to the vessel walls.
The above-described embodiments of the present invention provide a 5 safe, reliable means of breaking down a II.rombus with rolaling blades into particles which are fine enough to be left in the vascular system without any signiricant risk of forming additional thrombi. While prefe..ed embodiments of the present invention have been described, it should be understood that various changes, a.laplalions and modiricalions may be made therein without 10 departing from the spirit of the invention and the scope of the appended claims.

Claims

l. A mechanical thrombus maceration device comprising a. an elongate, flexible shaft having proximal and distal ends, the shaft being adapted to be guided along a vascular path and being rotatable within a vascular channel having a vascular wall:
b. a rotor affixed to the shaft adjacent the distal end thereof for rotation therewith;
c. drive means for rapidly rotating the shaft; and d. a rotor housing carried about the rotor and within which the rotor rotates, the housing comprising a generally cylindrical wall substantially surrounding the rotor and having at least one port formed therein, the port or ports being sized and positioned about the circumference of the housing such that when a fluid is ejected through the ports within a vascular channel, the housing will tend to deflect toward one side of the vascular channel to permit the device to be steered during deployment thereof within a patient's vascular system.
2. The device of Claim 1 wherein the rotor housing includes only one port and the housing will tend to deflect toward a side of the vascular channel opposed from the center of the surface area of the single port.
3. The device of Claim 2 wherein the port extends about no more than about 50% of the circumference of the housing.
4. The device of Claim 1 wherein the housing includes at least two ports disposed about the circumference of the housing, the surface area of one of the ports being different from the surface area of another of the ports.
5. The device of Claim 4 wherein the housing includes three ports, the surface area of two of said ports beings substantially the same and being different from the surface area of the third port.
6. The device of Claim 5 wherein the ports are spaced substantially equiangularly about the circumference of the housing and the third port has a surface area of about 20%
that of either of the two ports having substantially the same surface area.
7. The device of Claim 4 wherein the ports are not spaced equiangularly about the circumference of the housing.
8. The device of Claim 7 wherein each of the ports have approximately the same surface area.
9. A mechanical thrombus maceration device comprising:
a. an elongate, flexible shaft having proximal and distal ends, the shaft being adapted to be guided along a vascular path and being rotatable within a vascular channel having a vascular wall;
b. a rotor affixed to the shaft adjacent the distal end thereof for rotation therewith;
c. drive means for rapidly rotating the shaft; and d. a rotor housing carried about the rotor and within which the rotor rotates, the housing comprising a generally cylindrical wall substantially surrounding the rotor, the wall having an axis and having at least three elongate ports formed therein, the ports being spaced generally equiangularly about the circumference of the housing an having a major axis which is oriented obliquely with respect to the axis of the housing at an angle of from 20° to 45°.
10. A mechanical thrombus maceration device comprising:
a. an elongate, flexible shaft having proximal and distal ends, the shaft being adapted to be guided along a vascular path and being rotatable within a vascular channel having a vascular wall;
b. a plurality of rotors affixed to the shaft for rotation therewith, at least two rotors having blades, the rotors being spaced apart from one another along the shaft;
a. a drive means for rapidly rotating the shaft;
and d. a rotor housing enclosing a rotor and within which said rotor rotates, the housing comprising a generally cylindrical wall substantially surrounding the rotor and an intake port.
11. The device of Claim 10 wherein said rotors are carried along a distal segment of the shaft and the rotor housing encloses all of the rotors and includes a first discharge port passing through the wall of the housing at a location proximal of the distal-most rotor and an intake port disposed distally of the proximal-most rotor.
12. The device of Claim 10 further comprising a casing about the shaft, wherein a first of the rotors is positioned adjacent a distal end of the device and is adapted to macerate thrombi entrained in fluid in a patient's vascular system, and a second of the rotors is disposed proximally of the first rotor, the first and second rotors acting together to draw fluid into the device adjacent its distal end and pump that fluid rearwardly through the casing for removal from the patient's vascular system.
13. The device of Claim 12 wherein the second rotor is larger than the first rotor and displaces a greater volume of fluid than the first rotor when the shaft is rotated.
14. The device of Claim 13 wherein the casing is generally tubular and has a distal segment, a proximal segment and a tapered segment disposed between the distal end and proximal segments, the proximal segment, having a larger diameter than the distal segment, the tapered segment tapering relatively gradually from a diameter adjacent its proximal end substantially equal to the diameter of the proximal segment to a diameter adjacent its distal end substantially equal to the diameter of the distal segment.
15. A mechanical thrombus maceration device comprising:
a. an elongate, flexible shaft having proximal and distal ends, the shaft being adapted to be guided along a vascular path and being rotatable within a vascular channel having a vascular wall;

b. a rotor affixed to the shaft adjacent the distal end thereof for rotation therewith;
c. drive means for rapidly rotating the shaft;
d. a rotor housing carried about the rotor and within which the rotor rotates, the housing comprising a generally cylindrical wall substantially surrounding the rotor and having at least one port formed therein for discharging fluid out of the housing when the rotor is rotated, the port being spaced proximally of the rotor; and e. fluid directing means for directing fluid from the discharge port back toward the rotor; the fluid directing means is selectively configurable between a relatively compact deployment configuration and an expanded configuration for redirection of fluid.
16. The device of Claim 15 wherein the fluid directing means is expandable from a collapsed state for deployment to an expanded position wherein it directs fluid from the discharge port back toward the rotor.
17. The device of Claim 16 wherein the fluid directing means comprises a selectively inflatable balloon positioned adjacent a distal end of the housing.
18. The device of Claim 16 wherein the fluid directing means comprises a sheath formed of a flexible elastomeric material attached to the device proximally of the port, the sheath in its collapsed state covering at least a portion of the port and being expanded into its expanded state by fluid discharged through the port.
19. The device of Claim 18 wherein the sheath in its expanded state is generally frustoconical in shape, having a proximal end narrower than a distal end.
20. The device of Claim 15 wherein the fluid directing means comprises a gate adjacent the port, the gate being oriented at an angle with respect to the housing when fluid is discharged from the housing through the port to direct discharged fluid distally of the port.
21. The device of Claim 20 wherein the gate is normally biased toward the housing to substantially cover the port, the gate being hingedly attached to the device such that it will pivot outwardly of the housing in response to fluid being discharged from the port.
22. The device of Claim 21 wherein he housing includes a plurality of ports, one gate being positioned adjacent each port.