CA2112472C - Method and device for retrieving materials from body lumens - Google Patents

Abstract

A retrieval catheter (10) for removing deleterious materials (S) from body lumens comprises an elongate catheter body (12) having a slack net (28) at its distal end (16). The slack net may be collapsed to facilitate introduction into the body lumen and opened In situ to permit capture and retrieval of the deleterious materials. A
method for removing ureteral stones from the ureter is described.

Description

VSO 93/U2732 PCT/US92/~6169 ~ETxoD Ar~o DEVacE FoR RETRaEVaNG MATERaALs FROl~i BODY LUME~1S
r ~AC~GROTJND OF THE II~1VENTIOP1 1. Field of the Invention The present invention relates generally to the construction and use of medical instruments for retrieving l0 deleterious materials from body lumens. More particularly, the present invention relates to a catheter having a slack capture net at its distal end and means at its proximal end for openimg and clasing the net to capture and retrieve materials from body lumens.
The retrieval of ureteral stones remains a challenge and an occasional frustration to the treating surgeon. While blind retrieval techniques have been replaced by methods which employ direct visualization using a variety of endoscopes, tone retaeieval can still be troublesome because of 20 inadequacies i.n the retrieval device employed.
Conventional urete.ral stone retrieval devices fall into several cat~g~ries, including hasket.s; pincer-like forceps; ~raspers, and slings. Basket retrieval devices generally employ collapsible wise prong structures having 2~,relatively large openings which allow passage of small. stones and stcane fragments. The capture o~ large s1~ones can,also be di.f~icu~t since the stone wiJ.l frequent~:y himder movement of the basket in order to engage the stone. such baskets also have a tendency' to ,1~~e the stones as the ?gasket is being 3U withdrawn ~rom'the ureter.
The use' of p~.ncer-like forceps, graspere, and ~1'ings, is similar~.y problematic. such devices usually,can Capture only one stone at a time. Frequently, visid~a through the usetexoscope is sufficiently poor to render capture of 3~ single stones difficult.
For the reasons, it would be desirable tc~ provide improved devices and methods for capturing ureteral stones ~V~ 93/02732 PCf/US92/06169 during stone removal procedures. It would he particularly desirable if the device could be used for other medical procedures, including the removal of biliary stones from the biliary tract, the removal of atheroma and plaque from the vascular system, and the like.
2. Description of the Backcxround Art U.S. Patent No. 4,706,6X, describes an atheroma removal catheter having an expandable helical coil at its distal end. U.S. Patent No. 4,650,466, describes an angioplasty catheter having an expandable woven tube and optional internal filter for collecting plaque dislodged from a blood vessel by the tube. U.S. Patent No. 4,873,978, describes an expandable strainer which may be introduced downstream of an angioplasty procedure to capture released emboli. U.S. Patent 4,030,503, describes an embolectomy datheter having a helical wire structure at its distal end.
S'tY OF THE IN~IEN°°fION
The present invention provides improved devices and methods .~or the retrieval of material from body lumena. The device is a retrieval catheter which comprises a catheter body having a slack net at its distal end. The catheter further includes means at the proximal end of the catheter body far opening and closing or "collapsing" the slack net so that the catheter can be introduced into a body lumen with the net in its ~ol:lapsed configuration, and the net then opened after it reaches a desired 1~cation. The slack net comprises a ~aert~eab~.e fabric, ~rkaich may be elastic or not but is preferalaly a, s~,ightly elastic nylon or other fabric, so that it.pe~its fluid f1~w therethrough by remaining able to capture both urge and small particles, stones, stone fra~gmerats, and the like, with the capability of capturing many p~i,eces at a time. A somewhat elastic fabric is particularly 3a suitable since it can accommodate a large volume of material and will secure the captured material tightly to reduce the ~V~ 93/02732 PC'f/US92/Oblb9 likelihood that the material will be lost while the catheter is being withdrawn from the body lumen.
In a preferred embodiment, the slack net is mounted on a flexible loop which acts as an expandable frame for ' 5 holding the net. Usually, the flexible loop will have two ends, one of which is attached near the distal end of the catheter body and the other which is attached to a flexible core, such as a solid flexible pull-wire or a flexible cylindrical tube, which extends through a central lumen of the catheter body. Tn this way, the loop can be straightened so that it assumes a collapsed configuration, i.e., lying next to the distally extended pull-wire. By axially translating (pulling) the pull-wire in the proximal direction, however, the f3.exible loop will reassume a generally circular shape so that the slack net is opened and disposed to receive the material which is to be retrieved. Preferably, the: flexible look will be coated with or formed from a lubrirnus material, ~o~.~ p~efer~ably being coated with a hydrophilic material to facilitate introduction and manipulation of the catheter to and within the body lumen.
In the most preferred embodiment, the loop will be wrapped around he catheter body from ene-half turn (1.80°) to one full turn (360°). In this way, the slack net will be wound pertly or fully around the catheter body when the flexible loop is in'its collapsed configuration. Similarly, he net will extend partly or fully around the catheter body when the flexible loop is in its open configuration.
In the method of the present invention, the catheter b~dy is introduced o the desired body lumen, such as the 3~D ureter, biliary duct, blood vessel, bronchus, esophagus, 'bladder or the'like, with the slack net in its collapsed configuration. Usually, the catheter will be introduced, while being visualized by a conventional technique, such as uxete~~oscopy, fluoroscopy, or the like. Once in place, the ~5 slack net can be opened to extend across a major portion of the body lumen eo that it can capture solid material which may be present. The permeable nature of the slack net, permits ~V(~ 93/02732 ~ ~ P~'T/US92J06169 ~~ .~ i.a) '~

the flow of body fluids, such as urine, bile, blood, and the like therethrough. The solid material, such as ureteral and biliary stones, foreign bodies or other deleterious material may be captured by axially translating the catheter within the lumen so that the net engages the material. Alternatively, the net can be left stationary to cagture material which is carried by flowing body f?uid, e.g., emboli carried by the blood. In either ease, after the material is captured, the net care be collapsed to secure the material, and the catheter then withdrawn from the body lumen.
The invention can also be practiced without the slack net. According to this aspect of the invention, the catheter acts as an endoscopic retractor to enlarge a body cavity to facilitate medical procedures at the site of the flexible loop. For example, the distal end of the endoscopic retractor could be positioned along a body lumen adjacent a stone. y~hen pr~perly positioned adjacent a stone, the pull ~air~ is pulled to expand the flexible loop, thus opening the body lumen adjacent the st~ne. This provides other endoscopic devices, such as ultrasonic or laser probes, clear access to the stone to break up the stone.
gRIIFF' DES~JCPTIO~T OF TIC DRA'W1NGS
Fig. 1 is a perspective view of a retrieval catheter constrructed in acc~rdance with the principles of the present invention, shown with the proximal end in section.
Fig. 2 is a front end view of the retrieval catheter ~f F°~.s~. 1, taken from lane 2-2.
Fig. 2A illustrates an alternative embodiment of the d~.stal end of the retrieval catheter of Fig. 3..
Figs. 3A -- 3C illustrate use of the retrieval catheter of Fig, l in retrieving a ureter stone from the ureter s Figs. ~A - 4D illustrate use of an alternative embodiment of the retrieval catheter of Fig. 1 using a net which is less elastic than that of Fig. 1.

W~3 93/12732 PCr/U~92/~6169 ~~~~~~,%
Fig. 5A illustrates a body lumen having a stone therein and showing the distal end of an endoscopic probe adjacent the stone.
Fig. 5B illustrates the body lumen, stone and 5 endoscopic probe of Fig. 5A with the flexible loop member of an endoscopic retractor positioned between the distal end of the endoscopic probe and the stone, the endoscopic retractor being similar to that shown in Figs. 3C and 4C but without a net.
Fig. 6A shows an alternative embodiment of the endoscopic retractor of Fig. 5B having a pair of flexible loops.
Fig. 6g shows the endoscopic retractor of Fig. 6A in a use situation similar to that of Fig. 5B with the flexible loops in their radially extended conditions on either side of the stone.
DESCRIPTI~I~ ~F' TFIE SPECIFIC Et~ODIMENTS
The pr~~ent invention is useful for capturing and retr~.eving potentially harmful materials from body lumens, such'a~ ureteral stones from the ure~~r, biliary stones from the bili~~ry duct, athexoma and plaque from blood vessels, and he like. The device of the present invention is a retrieval catheter which comprises an elongate body having proximal and distal ends and a slack net at or near the distal end of the elongate body for capturing and retrieving the materials. The 'device further includes means for opening and collapsing the slack net whale the catheter is in situ within the desired body lumen. In thus way, the catheter can be introduced with 3~ the slack net collapsed so that the catheter has a minimum ~cr~ss-sectional area to facilitate introduction and placement.
The.~slack net can then be opened to permit capture of the body lumen materials; as described in more detail hereinbelow in connection with the method of the present invent~.on.
The catheter body may be flexible or rigid, although flexible catheters are preferred for mos applications. The length of the catheter body will vary depending on the .,~..
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, . ..,.... ,. ..x., i~l~ 93/02732 PCTlUS92l06169 ~, ~6~ ~r~ 4ir , application, with short catheters having a length in the range from about 40 cm to 100 cm, being preferred for stone removal applications from the ureter, biliary duct, and the like.
Longer catheters having a length from 50 cm to 150 cm will be preferred for most vascular applications. The diameter of the catheter body will also depend on the application. For use in the ureter and biliary duct, the catheter will usually have a diameter in the range from about 4 French to 12 French, usually being in the range from S French to 8 French. For ~.O vascular applications,,the diameter will usually be in the range from 6 French to 10 French.
Flexible catheter bodies will typically be formed as hollow tubes from extruded organic polymers, such as silicone rubber, polyurethane; polyvinyl chloride, nylon, and the like.
In some cases, it may be desirable to reinforce such polymeric catheter bodies, typically using a braided or other flexible reinforcem~n~ layer. Suitable materials and construction techniques for preparing tubular catheter constructions are well described in t~~ ~~dical and scientific literature and need not be described in detail herein.
The slack n~~ of the present invention will be permeable or porous to permit the flow of body fluids therethrough; but will define sufficiently narrow passages so thateven v~xy small st~ne fragments or other materials to be Captured will be unable to pass therethrough. Conveniently, ~t~e slack'net will be formed from a woven or non°woven fabric, ~r the 3ike, where the interstices between the fibers which dorm 'the fabric permit capture of t'h~ stone material while allowing flow of tfi:e body fluid therethrough. Such fabrics will be composed of a biocompatible material, typically being formed fx~im a natural fiber or an organic polymer, gireferably being formed from organic polymers. Thin metallic threads may I also be used. Suitable organic p~lymers include nylon, polyethylene, polypropylene; polyester, polytetraf luorethylene ~pTF~), polycarbonate, polystyrene; cellulose, pcalyacetonaarile, and the like. Individual fibers or bundles ~f fibers yarns) may be woven into the fabric by conventional VW'O 93/02732 PCT/US92/06169 ~~~~3'~
techniques, such as weaving, braiding, knitting, and the like.
The porosity of woven fabrics will be determined primarily by the interstitial spaces between the woven fibers or yarns, with looser weaves providing lesser flow resistance.
Particularly preferred for the present invention are fabric materials formed from threads which are thin and strong to form a fabric which is elastic or not. The fabric materials are preferably slightly elastic, such as elastic woven nylons of the type employed in conventional hosiery.
lp Referring now to the drawings, a preferred catheter construction for mounting a slack net at the distal end of an e~.ongate catheter body will be described. A retrieval catheter 10 comprises an elongate body 12 having a proximal end 14 and a distal end 16. A pull wire 18 extends through the axial lumen 20 of the catheter body 12 and includes a proximal end 24 and a distal end 22. The pull wiry ~.8 may be gormed from any material having sufficient compressive strea~gth and bending stiffness so that it can be used to manipulate slack net structure 26 mounted near its distal end.
2~ Us~~lly, the pull wire will be a hollow tube or a solid core wi.x,e, a twisted strand wire, a braided wire, or the like.
pa;~ticularly suitable materials and constructions of the type used in the construction of conventional guide wires.
The slack net structure 26 is secured to a flexible to~p member 28, which in turn is secured at a first end 30 to the e3.~ngate body I2 and at a secoaad end 32 to the pull wire 1,8, The slack net 2fi is attached along substantially the entire lengthof the flexible loop member 28 so that the pbsition and configuration of the loop member will necessarily 3Q def~.n~ the outer periphery of the slack net.
The slack net may or may not be secured 'to the pull :airs. If secured, the means for securing must be able tcz translate along the pull wire l8 as it is moved in and out of lumen 20 of the catheter body. For example, the slack net can be slidably secured with a plurality of rings 29 which slide along the pull wire 1.8 as the net is opened and closed.

i~VC193102732 PCT/US92/U6169 s'~a r~~

The pull wire 18 can be axially translated within the lumen 20 of catheter body 12 using a conventional three-ring actuator assembly 34 attached to the proximal end 14 of catheter body 12. The three-ring actuator assembly 34 includes a pair of side rings 36 and 38 attached to a central housing 40. A thumb ring 42 is secured to a plunger rod 44 which extends into the interior of the housing 40 and is secured to the proximal end of the pull wire 18. In this way, the treating physician can manipulate the position of the lU distal end of pull wire 18 relative to the distal end of catheter body 12 using a single hand.
It will be appreciated that the flexible loop member 28 can be "opened°' and °'collapsed" relative to the catheter body l2 and pull wire 18 by axially advancing or retracting l5 the pull wire. That is, by fully extending the pull wire 18 in the distal direction, the flexible loap member 28 will be collapsed so that it lies adjacent the pull wire~l8 (as best observed in Fig. 3A), thus closing the slack net structure 26.
conversely, by fully-retracting the pull wire 18 relative to 20 the catheter body 12 (as best observed in Fig. 3C), the loop member 28 will be fully opened as will be the slack net structure 26.
Referring,nbw to Figs. 2 and 2A, it can be seen that the attachment of flexible loop member 28 to the catheter 10 25 can be varied in order to change the geVmetry of the slack net st~°ucture 26 ~wh~n it is fully opened. In Fig. 2, the flexible member 28 is orierat~d substantially as illustrated in Fig. 1.
The d.~stal end 30 of the flexible loop member 28 is attached at the six o'clock position on the catheter body 12, while the 30 dlis~al attachment point 32 is attached at the 12 o'clock 'position on the pull wire l8. Thus, when the pull~wire 18 is fully x~et~acted and the loop 28 fu3ly opened, the 1~op will be prxmari~.y on one side of the elongate body 12. This is generally a preferred configuration.
35 An alternative configuration is illustrated in Fig.
2A, where flexible member 28' is wrapped around the pull wire one complete revolution (360°) so that the loop and net 26' fV~ 93!42732 ~ ~ ~ ~ ~ ~,~ % PC1'lIJS92l06119 will open up substantially symmetrically about the catheter when opened.
The flexible loop member 28 will preferably be formed from a resilient material possessing a memory so that, when the pull wire 18 is retracted, the loop will regain a preset circular configuration. Suitable memory materials include metals, flexible plastics, and the like.
Preferably, the flexible loop 28 will be coated with, a lubricous material to facilitate introduction and 20 manipulation within the desired body lumen. More preferably, the loop member will be coated with a hydrophilic material.
Such lubricous and/or hydrophilic materials are particularly desirable since they permit the distal end of the catheter 10 to be axially advanced and manipulated within the body lumen with minimal friction and binding. For example, such lubricous and/or hydrophilic loog members will permit the loop 28 and sleek net structure 26 to be passed around even relatively large stones in the ureter or biliary duct to permit capture and retrieval of such stones.
Preferred materials for coating the flexible member 28 .include that used on the Terumo Glide Wire made by Microvasive ref ~r~ston, Massachusetts.
Referria~g now to Figs. 3A°3C, the method of the present invention used for removing a ureteral stone S will be described. The catheter l0 is introduced to the ureter in a conventional manner,,such as through a cystoscope or a uret~rescope or over a guide wire.
Catheter 10 is inserted with the flexible loop member 28 fully collapsed, as shown in Fig. 3A. The catheter 3O is advanced until the ureteral stone S lies next to the flexible 'loop member 28 and slack net structure 26'. The net 26, pan then be opined by retracting pull wire 38 using the three-ring assembly 34. The net structure 26 is shown in a pa~~,ly opened configuration in Fig. 3S and in a fully opened configuration in Fig» 3C. After the net structure 26 is fully s~pened, the ureteral stone S may l~e captured simply by drawing V~~ X3/82732 PCT/US92/06169 p i L2d ii 10 the catheter 10 in the proximal direction so that the stone S
falls into the slack net.
The stone S may then be secured within the net 26 by forwardly advancing the pull wire 18 to collapse the net around the stone (not illustrated}.
Catheter 10 may be advanced over a guide wire as is routine in radiological or vascular procedures.
Figs. 4A - 4D illustrate an alternative embodiment of catheter 10 shown in Fig. 1-3C with like elements referred to with corresponding members. The primary difference between catheters 10 and 10~ i.s the use of a nonelastic slack net 26a versus the sla.ghtly elastic net 26 of Fig. 2. Fig. 4A
illustrates distal end of 24a before pull wire 18a has keen pulled or retracted. Fig. 48 illustrates catheter l0a with pull wire l8a partially retracted as body 12a has been pulled back slightly to4aards stone S. Fig. 4C illustrates catheter 10a raith pull wire 18a substantially retracted into body 12a having captured stone 8 within net 26a. Fig. 4D illustrates the structure of Fig. 4C after pull wire 18a has been extended ~~c~ t~'the general position of Fig. 4A, thin capturing stone ~ within net 26a f~r withdrawal of the stone from the body lumen ~r cavity.
Retrieval~catheter 10 can be modified through the i'omov~I of slack net structure 26 to create an endoscopic retractor 40 as shown ia~ Fig. 5~. Fig. 5A illu~tr~tes a body ~:umen 42 having a stone S positioned along the body lumen.
The distal end 44 of an endoscopic probe 46 is positioned slang b~dy lumen ~2 adjacent stone ~. The distal end 48 of en~osoapic retractor 40 is then passed through body lumen 42 until flexible to~p 50, similar to flexible loop member 28, is pe~sitioned between distal end 44 and stone ~. Pull :~~.re ' S2 is puled to cause f7~exible loop 50 to assume its radially , ~:ktea~ded positaon of Fig. 5~ to create an enlarged viewing region 54 surrounding loop 50. As is evident from Fig. 5~, this pr~vides an enlarged region for the manipulation of distal end 44 of endoscopic probe 46. When endoscopic probe 4~ is of an ultrasonic or laser probe used to break stone S

i~VQ 93/02732 PCT/iJS92/0~169 into small bits, this can be accomplished much easier with retractor 4o.
Fag. 6A illustrates an alternative embodiment of endoscopic retractor 40 by which a pair of axially separated flexible loops 50, 5oa are used. The structure at Ioop 50 is substantially the same as the structure in the embodiment of Fig. 5~. However, body 58 includes a body extension 60 which is used to connect but separate the opposed ends of loops 50, 50a. Flexible loop 5~a is secured at one end to body lO extension 60 and at the other end to body 58 while loop 50 is connected to pull wire 52 at one end and to body extension 60 at the other end. The use of endoscopic retractor 40a, by which fleatible loops 50, 50a are positioned on either side of stone ~, is shown in Fig. 6~.
Although the foregoing invention has been described in detail for purposes of clarity of understanding,~,it will be obvious that certain modifications may be practiced within the cape of the appended claims. For example, an additional tubular body could be Mounted over b~dy 12 so to slide over ~Q net structure 26 when in the collapsed position of Fig. 3A to mid insertion of catheter l0 into the body lumen. Once in posx~ion, the additional tubular body can be pulled back to ~x~ose net structure 26.

Claims (26)

WHAT IS CLAIMED IS:

1. A retrieval catheter comprising:
a hollow elongate body having proximal and distal ends;
a flexible loop member, having first and second securing ends, secured to the distal end of the body by the first securing end;
a slack net secured within the flexible loop; and means for opening and collapsing the loop, whereby the slack net can be opened in order to capture material and closed in order to secure the captured material.

2. A retrieval catheter as in claim 1, wherein the means for opening and collapsing the loop comprises means attached to the second securing end of the loop member for drawing the first and second securing ends together to open the net.

3. A retrieval catheter as in claim 2, wherein the means for drawing the two ends of the loop together comprises a pull wire which is slidably mounted within the elongate body.

4. A retrieval catheter as in claim 1, wherein the slack net comprises a permeable fabric.

5. A retrieval catheter as in claim 4, wherein the slack net comprises an elastic nylon fabric.

6. A retrieval catheter as in claim 1 wherein the second securing end of the loop member is attached to the means for opening and collapsing the loop.

7. A retrieval catheter comprising:
an elongate body having proximal and distal ends;

a pull wire having proximal and distal ends and being slidably mounted within the elongate body, wherein the distal end of the pull wire extends distally of the distal end of the said body;
a flexible loop member, having first and second securing ends, wherein the first securing end is attached to the distal end of the elongate body and the second securing end is attached to the pull wire near the distal end of said pull wire; and a slack net attached to the flexible loop, whereby the net can be shifted between an open and a closed configuration by axially shifting the pull wire relative to the elongate body.

8. A retrieval catheter as in claim 7, further comprising means at the proximal end of the elongate body for axially shifting the pull wire relative to the elongate body.

9. A retrieval catheter as in claim 8, wherein the axially shifting means is a three-ring actuator.

10. A retrieval catheter as in claim 7, wherein the elongate body is a flexible tube having a central lumen which receives the pull wire.

11. A retrieval catheter as in claim 7, wherein the pull wire is one of a hollow tube, a solid core wire, a twisted strand wire, or a braided wire.

12. A retrieval catheter as in claim 7, wherein the flexible loop member has a lubricous outer surface.

13. A retrieval catheter as in claim 12, wherein the flexible loop has a hydrophilic outer surface.

14. A retrieval catheter as in claim 7, wherein the slack net comprises a permeable material.

15. A retrieval catheter as in claim 14, wherein the slack net comprises an elastic nylon fabric.

16. A retrieval catheter as in claim 14, wherein the slack net comprises material coated with a hydrophilic material.

17. A retrieval catheter as in claim 16, where the slack net comprises an elastic nylon fabric.

18. A retrieval catheter as in claim 14, wherein the slack net comprises a material made from thin metallic threads.

19. A method for retrieving material in a body lumen, said method comprising:
introducing a hollow catheter body to the lumen, said catheter body having a collapsed slack net attached to a loop having two ends, one end being secured to a distal end of the catheter body;
moving the collapsed slack net past the material;
opening the slack net so that said net will extend across a portion of the cross section of the body lumen greater than a cross section of the catheter;
manipulating the slack net and optionally the catheter body;
capturing material within the opened slack net;
collapsing the slack net on the captured material; and withdrawing the catheter body from the lumen.

20. A method as in claim 19, wherein the body lumen is the ureter and the material captured is ureteral stones or other deleterious material.

21. A method as in claim 19, wherein the body lumen is the biliary tract and the material captured is biliary stones or other deleterious material.

22. A method as in claim 19, wherein the body lumen is a blood vessel and the material removed is atheroma or blood clot or emboli.

23. A method as in claim 19, wherein the body lumen is a bronchus and the material is a foreign body or other deleterious material.

24. A method as in claim 19, wherein the body lumen is an esophagus and the material is a foreign body or other deleterious material.

25. A method as in claim 19, wherein the body lumen is a bladder and the material is a stone or other deleterious material.

26. A method as in claim 19, further comprising the step of using an additional endoscopic device to break up the captured material within the slack net before withdrawing the catheter body.