CA1315634C - Mechanically locking blood clot filter - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A blood clot filter particularly suited for filtering blood clots from blood circulating through the inferior vena cava is composed of a number of peripheral wires joined at one end by a first connector and also joined approximately at their middle portions by a second connector. The wire portions extending between the two connectors form a filter mesh, and the wire portions extending between the second connector and the free ends form filtering legs which anchor the filter. The free ends have recurved hooks for radial engagement with a blood vessel. The filter mesh is formed by mechanically approximating the two connectors resulting in the formation of overlapping loops of wire. A central core wire is fixedly secured to one of the two connectors and slidingly extends through the second of the two connectors. The central core wire is retracted to slide the two connectors together. A lock device prevents the two connectors from sliding back apart. The wire strands may initially be substantially straightened in order to permit insertion of the filter into the lumen of an angiographic catheter. The catheter is positioned at a predetermined site within the vessel using standard percutaneous angiographic techniques from the groin or neck. A pusher catheter extending within a delivery catheter pushes the filter out of the delivery catheter and into the lumen of the blood vessel. A
retractor cable extends through the pusher catheter and is releasably coupled to the central core wire for retracting the same. Once the filter has been delivered into the blood vessel and the filter mesh mechanically formed, the legs are released to anchor the filter in position, and the pusher wire is disconnected.

Description

1 31 563~
` 1 ~CH~NICALLY ~OC~ING BLOO~ C~OT ~ILT~R

BAC~GROUND OF T~ INY~NTION

Field of the Inventio~
The pre~ent invention relates generally to devices or methods for filtering blood clot~ from blood ve~sels, and more particularly to vena cava blood clot filter~ and methods and apparatu~ for in~erting such vena cava blood clot filters transvenously.

Back~round of the Invention ~t i8 e~timated that each year, approximately 750,000 patient~ in the United States suffer pulmonary emboli~m or passage of blood clots to the lungs. O$ the~e, approximately 150,000 patients die each year from such pulmonary embolism. Most commonly, these clots originate in the veins of the pelvis or lower limbs. While most patients can be treated with blood thinning medications, these medications can jeopardize the wellbein~ o~ some patients becau~e of other, co-existing medical problems.
Other patients exhibit recurrent embolism even while being treated with these medications. In these situations, a mechanical barrier is neces~ary to prevent such blood clots from travellin~ through the inferior vena sava to the heart and lun~s.
Initially, surgical procedures were devised to form ~uch ~5 a ~echanical barrier. These procedures consis~ed of either tying a ligature around the inferior vena cava or placing a special clip around it. The sur~ery necessary to perform this procedure is exten~îve and requires a general ane~thetic. Moreover, such ~urgical procedure~
si~nificantly ~urther jeopardize the health of an already ill patient.
Over the last ~i~teen years, several devices have been used to place a filterin~ device into the inferior vena cava usin~ a tran~venous route, commonly originatin~ from 2 131 5h3~
the ri~ht jugul~r vein or from either femoral vei~. For example, the method disclo~ed in U.S. Pat~nt No. 3,834,394 to ~unter, et ~1., use~ a detachable bnlloon which i~
deliver2d to the inferior ven~ cava at ~he end o a ~atheter. The balloon and cathete~ are inserted into one of the veins in the neck u~ing a ~urgical incision a~d passed to the lower inferior vena cava ~here the balloon is inflated. Once det~ched, the ~alloon occludes the inferior vena cava entirely, thereby preventin~ any flow o~ blood or blood clots to ~he heart. While insertion of ~his device avoid~ major abdominal surgery, it Ctill requires a ~mall surgical procedure to be performed in order to 0xpo~e a neck vein. The balloon occlude~ the inferior vena cava compleSely, resulting in s~elling of the lower extremitie3 until collateral circulation develops around the balloon.
With time, these collateral Ghannel~ may beco~e large enough to permit life threatening emboli to pass to the lung.
Another device for preventing pulmonary embolism but which does not require total occlusion of the inferior vena cava i5 an implantable cone-shaped filter device consisting of six spoke~ with sharpened points at the end and connected together at the other end by a central hub. A
thin membrane ~ith 4 ~m. holes covers the device. The umbrella-like device is folded into a cylindrical capsule connected to the end of a catheter. This device is described in U.S. Patent No. 3,540,431, to Mobin-Uddin.
Thi3 device also requires a ~uryical cutdown on a major rig~t neck vein for acce~s to the venous system. The device and delivery cap3ule are po~itioned in the inferior vena cava and released by pu~hing the device out of the capsule. While the device acts as an efficient filter, approximately 60% of the patient~ U5i~ the Mobin-Uddin filter develop occlusion o~ the i~ferior vena cava, sometimes resulti~g in severe s~ellin~ of the legs.
Furthermore, in~tances of mi~ration of the filter to the 3 1 3 1 56~
heart have been reporte~; ~uch ln~tance~ pre~ent a hi~h mortal~ty ri~k.
The Hunter balloon and the Mobin-Uddin umbrella su~er from ~imilsr disa~vanta~e~ in that they require a ~ur~ic~l procedure on the neck for expo~ure of a vein into which the filter may be pa~ed. Furthermore, morbidity from occlusion of the inferior vena cava could be ~evere. A
device which coul~ be ea~ily in~erted from the ~emoral approach u~ing ~tandard angiographic technique~, and thereby avoid 3urgery, ~ould be de~irable. Ideally, the device ~hould not totally occlude the inPerior vena cava or be thrombogenic. It ~hould alao be ~ecurely ~nchore~
within the inferior vena cava to prevent migration.
U.S. Patent No. 3,952,747, to ~immel, di~closes a blood ve~sel filter and filter insertion in~trument which overcome some of the di~advantage~ of the previous two devices. The Rimmel patent de~cribe~ device which may be inserted either from the jugular or femoral approach u~ing a ~urgical exposure of a major vein. The conical ~haped ao device consists of 8iX strands of wire each connected to a hub at one end and having recurved hooks on the other end.
~he aevice i8 loaded into a cylindrical delivery capsule which is connected to a catheter. The ~elivery cap~ule measures 6 ~m. in diameter and 5 cm. in length. Becau~e of its 3ize, a surgical exposure of the vein is necessary ~or introduction of the delivery capsule into the vascular system. Nore recently, the delivery cap~ule ha~ been introduced into the vascular sy~tem through a large catheter usin~ angio~raphic technique~. However, this technique has been ~hown to signi~icantly injure the vein at the introduction site. Sometimes it may not be po~ible to pas~ the cap~ule from below through tortuou3 pelvic vein~ into the inferior vena cava because of the inflexibility of the ~apsule. The filter engages the ~all of the vein at one end and there~ore often tilt~ to one side. It is very di~ficult to deliver the filter in a 13 1 5G3~
manner that maintain~ the longitudinal axis of the fllt~r centere~ alon~ the lon~itudin~l ~xi~ o the vena cava. A
tilte~ filter ha~ been ~ho~n to be le3~ efficient at capturing blood clots. ~igration of the filter ha~ not been A problem.
Another method of preventin~ pulmonary emboli from reachlng the lun~ i8 a device di~clo~ed in U.5. Patent No.

4,425,908, to Simon. Thi~ device uses the thermal ~hape memory proper~ie~ of Ni~inol to deploy the filter following delivery. The filter consi3~ of ~even wire3 banded at one end and al80 in the middle. The wire~ bet~een the~e two points form a predetermined filter me~h derived from the thermal memory. The free-ends of the ~ires ~orm anchorin~
points which radially engage the inferior vena cava. The device may be inserted through a jugular or femoral vein approach usiny standard angio~raphic catheters. The device reli@s on the thermal shape memory properti0~ of the Nitinol ~ire to form an effective filter following delivery. It i nok yet clear whether the filter di closed in the Simon patent will be biocompatible in humans or if it will be thrombogenic. Concern exi~t regarding its reliability when ~tored at different temperature~ and also whether the ~aterial can be manufactured with the ~ame consi~tency.
U.S. Patent No. 4,494,531, to Gianturco, also disclo3e~
a blood ~es~el ~ilter which can be inserted through angiographic catheter~. The device con~ist~ of a number of strands of wire which ~re interconnected and wadded together to form a curly wire mesh. The filter includes a number of projection~ which serve as an anchorinq means for anchorin~ the filter at a ~uitable body location within the inferior vena cava. Problem~ with the device include migration and demonstration invitro of filteriny inefficiency. The random nature of the filtering mesh make~ it difficult to as~es~ the overall efficacy.
Perforation of the anchoring limb~ throu~h the vena cava ha~ al~o been de~crib~d.
A devi~e de~cribed by Gunth~r e~ al. in a 1985 tech~ical article con~i~t~ of a helic~l ba~ket made oP a number of ~ire3 and radially placed legs. Originally, it ~a~
intended to be implanted te~porarily in the in~erior vena cava until the ~atient'~ risk o~ ~ulmonary embolism had passed. Limited clinical experience i~ aqailable.
The blood clot filter device and related delivery apparatu~ disclosed in the pre~ent invention, overcome the disadvantagea associated with the prior art by employin~ a nonocclusive filter ~hich i~ de3igned to be inserted into the vena cava using normal percutaneous catheterization techniques through a femoral or jugular approach. Thus the need for surgery i~ totally eliminated. The device is ~elf-centering and has a positive mechanical locking system. This sy~tem does not require the patient to b2 at a ~iven temperature in order for the filter to ~orm it~
~hape. Moreover, it i~ made of metal~ which have been shown to be biocompatible ~hen used in other devices such as pacemakers and inferior vena cava filters. This is not true of the filter di~clo~ed by Simon. The filter configuration i8 predetermined and not random as described by Gianturco.
Accordingly, it i5 an object of the present invention to provide a blood clot filter ~hich may be implanted using normal percutaneous an~io~raphic catheter techniques through either a femoral or ju~ular approach.
It i~ a further object of the pre~ent invention to provide a blood clot filter ~hich i5 designed to be placed ~ithin the inferior ~ena cava below the renal veins.
It is yet a further object of the pre~ent invention to provide a blood clot filter ~hich does not obstruct blood flow ~ithin th~ blood vessel at any time.
It is ~till a further object of the present invention to provide a blood clot filtsr ~hich ~ill not cause thrombus formation or emboli after implantation.

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An additioDal obj~ct of the pre~ent invention iu to provide a blood clot filter ~hlch i~ capable of being aecurely anchored within the blood ve~sel.
It i~ a further object of the pre~ent invention to provide a blood clot filter which forms it~ ~hape u~ing mechanically induced conver~ion of ~traight wireR into a filter mesh ~hich may accommodate vena cava~ of varying sizes.
It i9 another object of the pre3ent invention to provide such a blood clot filter which uses well-known biocompatible materials and which avoids reliance upon thermal memory shape characteri~tics, thereby providing a reliable and less expensive filter.

Sum~arv of the Invention --~ ~ Ihè present~invention provides a blood clot filter which includes a central core wire extending ~long a central longitudinal axis and surrounded b~ a number of peripheral wires evenly spaced about the central core wire.
A first connector connects the peripheral wires together at one end of the central core wire at a fir~t fixed connection point. A second connector connects the peripheral wires together at a second connection point spaced apart from a the first connection point, the second ~5 connection point surrounding the central core wire and being slidably secured thereto. The blood clot filter includes a one-way lock device permitting the second connector to slide along the central core wire toward the first fixed connector from a first ~osition remote from the first connector to a second position proximate the first connector. However, the lock device prevents the second connector from returning from the second proximate position back to the first remote position. The p~rtions of the peripheral wires extending between the first and second connectors initially extend generally along the central L' r~

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core ~ire. A~ the ~econd connector i8 advance~ from the fir~t re~ot~ po~ition to the aecond proxl~ate positio~, the por~lo~ of khe peripheral ~ire~ extending between the firat and oecond connector~ ~ov~ radially away from the central core wire to a deployed po~ition ~or forming a ~ilter mesh.
In a prePerred embodiment of the pre~ent invention, the peripheral wire~ include leg portion~ ~hich exten~ beyond either the ~ir~t or ~econd ~onnector~ The leg portions are biased a~ay from the cen~ral lo~gitudinal axi~ of the blood clot filter and terminate in hooked feet adapted to enya~e the walls of a blood vessel for anchorin~ the blood clot filter at a desired location therein. The leg portions provide a second ~ilterin~ component in addition to the flattened fil~er mesh, and the leg portion~, in conjunction ~ith the ~lattened filter me~h, automatically center the blood clot filter ~ithin a blood vessel and prevent the Bame from tilting away ~rom the central longitudinal axi~.
The aforementioned ~econd connector may be in the form of a tubular sleeve which slide~ over the central core wire. ~ach of the peripheral ~ires may be attached, a~ by weldin~, to the exterior ~all of the tubular ~leeve. In another embodiment of the present invention, the ~econd connector i8 in the form of a collar through which each of the peripheral wires pa~es, the ~ollar 3erving to collect and connect the peripheral wires to permit the ~ame to ~lide along the central core wire.
A first embodiment of the prs~ent inYention i9 primarily desi~ned for delivery u~ing a tran~femoral approach. In this embodiment, the a$orementioned fir~t connector join~
first ends of the peripheral wire~ together a~d fixedly ~ecure~ the ~ame to a first end of ~he core wire. The ~econd connector join3 central portions of the peripheral wire~ to one another for ~liding alo~g the central core wire. The second ends o~ the peripheral wire~ extend from the ~econd connector to provide the aforementioned le~

~ - 1 31 5634 portion~. The central core ~ire extend~ beyon~ the aecond connector and beyond the ~acon~ ~nds of the ~2ri~heral wires for being retracted to ~e~loy the flattened filter me~h.
A ~econd embodiment of the present invention i~ adapted for deli~ery using a tran~jugular approach. In this embodiment, the fir~t connector join~ the central portion~
of ths peripheral ~ire~ together and fixedly ~ecure3 the ~ame to the first end o the central core ~ire. The -~econd connector join~ first end~ of the peripheral wires to one another and ~lidin~ly secure~ the same about the central core wire. The second end~ of the peripheral wires extend from the first connec~or to form the le~ portions. The central core wire extends through and beyond the ~econd connector in a direction oppo~ite to which the leg portion~
extend. The second end of ~he central core ~ire is again adapted to be retracted for deploying the filter me~h.
The pre~ent invention al80 contemplate~ a filter delivery apparatus for use in conjunction with a blood clot ao filter of the type ~ummarized above. The filter delivery apparatus includes a delivery catheter having a distal end for percutaneous introduction into A blood ve~sel, the distal end of the delivery catheter being adapted to deliver the blood clot filter ~ithin the blood vessel. A
as pusher catheter i8 ~lidin~ly received ~ithin the delivery catheter through the proximal end thereof. The distal end of the pu~her eatheter i~ advanced into the delivery catheter until it abuts the blood clot filter. Retraction of the delivery catheter, ~hile maintaining the pusher catheter en~ayed ~ith the blood clot filter cause~ the leading portion of the blood clot filter to be delivered from the distal end of the delivery catheter.
The filter delivery apparatus further includes a retractor cable which ~lidinyly extend~ throu~h the pusher catheter and which i~ relea~ably coupled to the re~raction end of the central core ~ire. By pulling back on the 9 1 31 563~
retractor ~ble ~hile main-tainin~ the pu~her catheter in abutment ~ith the bloo~ clot filt~r, the u~er force~ the filter me~h to become locked in its ~e~loyed configuration~
Further retraction of th~ ~livery catheter while maintaining the pusher catheter fixed release~ the blood clot filter entirely out of ~he di~tal end of the delivery catheter, permitting the leg portions to ~pring outwardly and engage the ~all~ of the blood ve~sel. Retraction of both the delivery catheter and pu3her catheter then permit~
the retractor cable to be disen~aged from the retraction end of the central core wire. The delivery apparatus may then be removed, leaving the blood clot filter in the desired location.

Brief Description o~ the Drawin~s Fig. 1 is a side view of a blood clot filter con~tructed in accordance ~ith the teachin~ of the present invention and de~i~ned for percutaneou~ introduction and delivery usiny a transfemoral approach.
Fig. 2 is a frontal view as viewed through the plane indicated b~ line~ 2-2 in Fig. 1.
Fig. 3 is a ~ectioned view o~ the filter device ~hown in Fig. 1, as viewed from the plane indicated by lines 3-3 in Fig. 1 and illustrating six anchoring legs f or anchoring the blood clot filter at a desired location in a blood ve~sel.
Figs. 4A, 4B, 4C, AD, 4E and 4F illustrate the deliv~ry and deployment of the blood clot filter shown in Fig. 1 using a novel filter delivery apparatus.
Figs. 5A and 5B are per~pective and cro~ ectional vie~s, respectively, of one form of releasable couplin~ for releasably connecting a retraction end of a central core wire within the blood clot filter to a retractor cable ~ithin the delivery apparatu~.
Fig~. 6A and 6B are per~pective and top views, re~pectiv01y, of a ~econd form of releas~ble coupling for ~ 1 31 563~
relea~ably connectin~ the retrAction end oP the central core ~ire ~ithi~ the bloo~ clot filter to the retractor cable.
~ig. 7 i~ a side vie~ of a blood clot filter ~imilar to that ~hown in Fig. 1, but wherein the anchoring leg~ are curved rather than ~traight, and are o~ different le~gth3.
~ ig~. 8A, 8B, and 8C ~re ~artially cut a~ay ~etailed Vie~B of a lock device for lockin~ the filter me~h sf the blood clot filter in a deployed po~ition and ~imultaneouYly ~preading the anchoring legs to more firmly anchor the ~lood clot filter ~ithin the blood vessel.
Fig . 9 i5 an alternate form of lock device in the form of a one-~ay wa~her which slide~ in one direction along the central core wire, but not in the opposite direc~ion.
Fi~s. lOA, lOB, and lOC are cross-~ectional side ~iew~
of an alternate form of blood clot filter intended ~or percutaneou~ introduction and delivery using a tran~jugular approach, together ~ith a delivery apparatus for introducing such blood clot filter.
Fig. 11 i~ an al~ernate ~orm of delivery apparatus including a delivery catheter in ~hich the blood clot f ilter may be pre-loaded at the di~tal end thereof, and further including an outer catheter into which the delivery catheter may be in~erted for gaininSI access to the blood ves~el.
Fig~. 12, 13, 14 and 15 illu~trate variou~ stages in the delivery of the blood clot filter using the filter delivery apparatu~ shown in Fi~. 11.
Fig. 16 i~ a sectional vie~ of the slidable connector shown in Fig. 1 as viewed through the plane indicated by lines 15-16 in Fig. 1, wherein the ~lidable connector i~ in the form of a collar encircling th~ peripheral wire~ o~ the blood clot f ilter .
Fig. 17 is a sectional view of a ~lidable connector in the form of a tubular ~lee~e ~urrounding the central core wire and having a circular exterior wall to ~hich the 1 31 5~3ll, peripheral ~ir~ are nttached.
Fig~. 18A, 18~, and 18C are sectioned vie~ of an alternate orm o~ lock device for ~e~hanicall~ lockin~ the filter ~e~h of the blood clot filter in the deployed, flattened confi~uration.
Fi~. 19 show~ the proximal end of a delivery cathet~r, as well as a filter ~torage tube in ~hich the blood clot filter may be preloaded.
Fig. 20 illu~trate~ a ~ire sha~ing jig ~hich may be u~ed to form the peripheral ~ires that are u~e~ to conatruct the blood clot filter.
Fig. 21 disclo~es an assembly ji~ ~hich may be u~ed during assembly of the blood clot filter in order to hold the central core ~ire and peripheral ~ire~ in place during a~sembly.

Detailed DescriPtion of the Preferred ~m~odimsnt~
In Fig. 1, a blood clot filter of the type intende~ for percutaneous introduction and delivery u~in~ a tran~femoral approach i3 ~hown and iB designated generally by reference numeral 20. Within Fig. 1, dashed lines 22 and 24 indicate the outline of an interior wall of a blood v~ssel, ~uch as tha inferior vena cava. Blood clot ~ilter 20 con~ist essentially of a central core wire 26 which extends generally along the central lonsitudinal axis of blood clot filter 20, as well as 3ix peripheral ~ires 28, 30, 32, 34, 36 and 38 spaced equiangularly about central core wire 26.
Peripheral wires 36 and 38 are hidden from view in Fig. 1 by peripheral wires 30 and 32, respectively; however, peripheral wires 36 and 38 are vi~ible in Fig~. 2 and 3.
In Fi~. 1, a first connector 40 is 3hown forming a nose of blood clot ~ilter 20. Connector 40 serve~ to connect together a first end of each of peripheral wires 28-38, and attaches such peripheral ~ires about the firqt end of central core ~ire 26 at a fir~t connection point.

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Connactor 40 i8 ~elded, crimped or otherwiae attached to the f~rst an~ of cantral core ~ire 26 ~n~ ~o the f irat en~
of peripheral wires 2B-38 ~o that a $ixed ~onnection i~
achieved between the central core wire an~ the ~ix peripheral wires.
Still referring to Fi~. 1, ths ix peripheral ~ires 28-38 are again joined along their central portions by a second connector 42. As ~ho~n best in Fi~. 16, connector 42 i in the for~ of a tubular collar havin~ a central opening defining an interior wall 44. ~ach of the peripheral wires 28-38 passes throu~h tu~ular collar 42 and is ~ecured to interior ~all 44 thereof, as by ~elding or by other means of attachment. Thu~, ce~ond connector 42 serves to connect toge~her peripheral ~ires 28-38 at a second connection point spaced apart from the fir~t connection point at first connector 40. Referring again to Fig. 16, it ~ill be noted that central core wire 26 passes freely through the interior space de~ined by tubular collar 42 and the peripheral wire ~ecured therein, thereby allowin~ 3econd connector 42 to ~lide along ~entral core wire 2G.
Referring briefly to Fig. 17, ~n alternate form of second connector i~ shown designated by re~erence numeral 42'. Second connector 4~' includes a tubular sleeve 46 having a central bore 48 through which central core wire 26 extends. Tubular ~leeve 46 includes an exterior circular wall 50 to which each of peripheral wires 28-38 are attached, as by welding. Like connector 42 shown in Fig.
16, connector 42' sho~n in Fig. 17 slidingly secures the central portions of peripheral wires ~8-38 about central core wire 26.
Within Fig. 1, second connector 4~ is shown after having been advanced to a position relatively proximate to nose 40. The portions of peripheral ~ire~ a8-38 lying between fir~t connector 40 and ~econd connector 42 are shown as formin~ a ~lattened filter mesh, desi~nated generally by - `
.

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reference numeral 52. B~ch of the portion~ of peri~heral wires 28-38 l~ing bet~een fir~t connector 40 ana ~econd connector 42 rotate~ through an an~le of a~proximately 90-120. A~ ~econd connector 42 ~ advanced to~ard fir~t connector 40, the portions of peripheral wires 28-38 lying between fir~t connector 40 and ~econd connector 42 extend radially away from central core wire 26, to a flattened, deployed po~ition sho~n in Fig~. 1 and 2. As ~hown in ~ig.
lj the extreme outermost portions of flattened filter me~h 52 sngage and slightly distend the interior walls 22 and 24 of the blood vessel, thereby providing a filter me~h which extends over the entire cross-sec~ional area of the blood vessel and which help locate blood clot filter 20 along the central axis of the blood vessel once the leg portions of the peripheral wire~ 28-38 are relea~ed. ~7hen ~ilter mesh 52 is fully deployed, it extends sub~tantially perpendicular to central core ~ire 26, and substantially perpendicular to the longitudinal axi~ of bloo~ clot filter 52.
As mentioned above, the peripheral wires 28-38 rotate through an angle of approximately 90-120 as filter mesh 52 is deployed to facilitate the flattening of the filter mesh. Peripheral wire~ may be pre-shaped during manufacture of blood clot filter 20 by proximating nose connector 40 and slide connector 42 and turning nose connector 40 through an angle of approximately 90-120 while holding ~lide connector 42 fixed, and then heat-treating filter 20 so that the elastic memory of the peripher~l wires will cause filter mesh 52 to flatten when core wire 26 is retracted.
As shown in Fig. 1, the end~ of peripheral wires 28-38 lyin~ opposite connector 40 pass outwardly through slidable connector 42 in a direction generally opposite to that of connector 40. These second ends of peripheral wires 28-38 form anchoring le~s, each of Nhich is biased away from the central l~n~itudinal axis of blood clot filter 52. The~e 14 l 31 563~
anchoring leg~ coll~ctively form a le~ ~s~embly ~e~i~nated by reference numeral 51. Each of ~he 1Qg portion~ of peripheral wire~ 28, 30, 32, 34, 36 and 38 terminate in sharp2ned hoo~ or feet 54, 56, 58, 60, 62 and 64, re~pectively for engaging and becoming fixed wi~hin the interior ~alls 2~, 24 of the blood vex~el to anchor and maintain blood clot filter 52 at a de~ired location therein. Apart from anchoring blood clot filter 20, the leg portions of peripheral wire~ 28-38 independently form a blood clot filter ~eparate and apart from flattened filter me~h 52. While leg assembly 51 is sho~n as bein~ formed by extensions o~ peripheral wires 28-38, it will be appreciated that the wires forming ~uch legs may be di~tinct from peripheral wire~ 28-38, and may differ in number and thickne~s therefrom. Thus, blood clot filter 20 provide~ a dual filtering sy~tem capable of filtering blood clots greater than 5 millimeters in diameter. Moreover, as mentioned above, the leq portions of peripheral wire~ 28-38, in combination ~ith filter mesh 52, provide a self-centering device maintaining blood clot filter 20 centeredwithin the blood vessel, thereby avoiding problems associated ~ith a tilted filter.
Central core wire 26 and peripheral wires 28-38 may all be formed from stainless steel, ~ material which has been used extensively within the vascular system, and which i~
accepted by regulatory agencie~ and the medical comm~mity.
Connectors 40 ~nd 42 may al~o be made of stainles~ steel.
Alternatively, the central core ~ire, periphsral wires and connectors may be formed of titanium. It i8 believed that a peripheral wire thickne~s of 0.010 inch is thick enough to withstand the impact of a blood clot againæt blood clot filter ao, while being thin enough to be able to be deployed into the filter mesh 52 shown in Fig. 1 without requiring excessive mechanical force. Moreover, it is believed that a wire thickness of 0.010 inch allows the filter ~e~h 52 to he yieldin~ enough to accommodate a 1 3 1 563~
variety ~f caval 3iZ~8.
Tho~e ~killed i~ the art ~ill A~preciate that blood clot filter 20 mu~t ini~ially be provided a~ a ~lender, ~mall diameter as3embly in vrder to be conveniently introduced within the blood ve~el by a delivery catheter. The leg portions of peripheral wires 28-38 may initially be compressed inwardly toward central core wire 26 prior to loading the device within a delivery catheter, a~ 3hown in Fig. 4A. The length~ of the various leg~ may be varied to facilitate loading within the delivery catheter. The filter ~esh sa i8 initially maintained in a compact, elongated form by initially positioning slide connector 42 at a fir~t po~ition relatively remote ~xom connector 40 a~
shown in Fi~. 4A. In this initial position, the portions of peripheral wire~ 28-38 extending bet~een connector 40 and slide connector 42 lie generally along central core wire 26, as shown in ~ig~. 4A and 4B. Only after filter mesh 52 is positioned within the blood ves~el at the desired location is filter mesh 52 deployed outwardly to take on its flattened, mesh configuration shown in Fig. 1.
Aæ ~hown in Figs. 1 and 4A, central core wire 26 is longer than peripheral wires 28-38, and the second end of central core ~ire 26 oppo~ite connector 40 include~ a retractor fitting, ~hown in Fi~. 1 a3 a bent or hooked end a5 66. ~hen filter me~h 52 i8 to be deployed, central core wire 26 is retracted by pulling on retractor end 66, thereby c~usin~ first connector 40 a~d ~lide connector 42 to approach one another, and causin~ the portions of peripheral wires 28-38 lyin~ between connectors 40 and 42 to extend radially outward and ~latten. Were retractor end 66 to be relea~ed, the force of blood vçs~el ~alls 22 and 24 upon filter me~h 52, together with the inherent memory characteristics of fine steel wire, would tend to force connector~ 40 and 42 apart back to the initial po~ition shown in Fi~ 4B. Accordingly, blood clot filter 20 include~ a mechanism ~or lockin~ ~lide connector 42 in the 1 31 563a, " 16 po~ition shown in Fig~ 1 after central core wir~ 26 has b~en retracted in order to maint~in filter mesh 52 in the deployed, collapsed po~ition. One manner in ~hi~h thi~ may be accomplished is by f lattenin~ or thickening the ~ortion of central core wire 26 adja~ent nose connector 40 ~hereby second connector 42' (~ee Fig. 17) forms a friction fit ~ith central core wire ~6 a~ connector 42' ~lides toward nose connector 40. An alternate manner of loc~ing slide connector 42 proximate no~e connector 40 i~ sho~n in Fig~.
8A-8C. In Fi~. 8A, lock device 68 is sho~n as a cylindrical member extendin~ around central core ~ire 26 bet~een ~econd connector 42 and retractor end 66 (see Fig.
1) of central core wire 26. Lock device 68 includes a wedge-shaped in~erior bore of a diameter commensurate ~ith the diameter of the central body of core wire 26. The wedge-shaped interior bore of lock device 68 open~ toward nose connector 40. The diameter of core ~ire 26 is essentially uniform until reaching the vicinity of no~e connector 40, at ~hich point core wire 26 gradually tapers to an enlar~ed diameter. L~ck device 68 can ~reely slide along central core wire 26 toward no~e connector 40 (see - Fig. 1) until reaching the tapered portion of core wire 26, at which point further retraction of core wire 26 causes the same to become ~edged within lock device 68, thereby a5 oppo~iny sliding motion in the oppo~ite direction. Prior to delivery of the blood clot filter, lock device 68 i po~itioned behind the feet 54-60 of leg a~embly 51, thereby allowing the leg portions of peripheral wires 28 and 34 to lie generally alongside core wire 26 in a compact form. ~o~ever, when central core ~ire 26 i~ being retracted, ~s shown in Fig. 8B, lock device 68 is simultaneou~lr urged toward slide connector 4~ and toward nose connector 40 by the di~tal end of a pu~her catheter 70 to be de~cribed in greater detail below. Thus, lock devic 68 al~o functions as spreader for biasing the leg portions o~ peripheral ~ire~, such ~8 23 and 34, away from central core wire 26. ~n ~i~. 8C, the di~tal end of the pu~her ca~heter 70 1~ retract~d. Lock dovice 68 thereafter oppo~es sliding motion of central core wire 2~ relative to ~lide connector 42, thereby maintaining filter ms~h 52 (~ee Fig. 1) in it~ deployed po~ition, while ~imul~aneou~ly urging the leg portion~ of the peripheral ~ire~ 28-38 radially outward.
Fig. 9 ~hows an alternate form of a lock device. Within Fig. 9, one-way ~asher 7~ include3 a c~ntral region angled toward the leftmost side of Fig. 9. A central aperture 74 formed within the central region of washer 72 re~eive~
central core wire 26. A ~eries of radial ~lot~, ~uch as 76 and 78 divide the angled central regio~ into a ~erie~ of tabs. Consequently, on~-way wa~her may ea3ily be moved to the right alons central core wire 26 ~ithin Fig. 9.
Howev~r, attempts to thereafter move one-way wa~her 72 to the left cau~e the slot~ed tabs to dig in to ~entral core ~ire 26 and oppose further sliding movement. A lock device ~uch as one-~ay ~asher 72 could be substituted for lock device 68 within Fi~s. 8A-8C and likewise prevent central core wire 26 from sliding through slide connector 42 after having been retracted.
Fig8. 17 and 18A-18C illustrate an alternate form of lock device for the blood clot f ilter ~0 ~hown in Fig. 1.
As ~tated above in regard to Fig. 17, slide connector 42' is in the form of a tubular sleeve 46 ~hich slidingly passes therethrough. ~ach of the 8iX peripheral wires 28-38 i5 secured to the outer ~urface of tu~ular sleeve 46, as by weldin~. Referring to Figs. 18A-18C, peripheral wires 28 and 34 ~re shown as being attached to the outer surface of tubular sleeve 46, as by welding. A locking device, in the form of a ~edge-shaped re~ilient member 71 i~ ~hown ~ixedly secured to central core wire 26. Wedge 71 is initially to the right of tubular ~leeve 46 when the ~lood clot filter is in its compacted form prior to deployment.
The ~arrowe t portion of ~hich 71 lies clo~est to tubular 18 1 31 563~
~leeve 46, while the wid0st portion thereof i9 ~urthe~t from tubular 31eeve 46. The ~ide~t port~on of ~ed~e 71 has a diameter or width which exceed~ the internal diameter of tubular ~leeve 46. However, ~ed~e 71 i~ made of a ~ufficiently deformable material as to allow ~edge 71 to be pulled through tubular ~leeve 46 upon retraction of central core wire 26, a~ shown in ~ig. 18B~ Referring to Fig. 18C, cenkral core ~ire 26 ha~ been fully retracted, thersby bringing nose connector 40 of blood clot filter 20 into proximity with tubular ~leeve 46 for deploying the filter mesh 52. As shown in Fig. 18C, ~edge 71 no~ lies to ~he left of tubular sleevs 46, and because the ~idest por~ion of wedge 71 i~ wider, or of greater diameter, than tubular sleeve 46, central core wire 26 i8 pre~ented from ~liding back to the right. Accordingly, the filter mesh 52 is locked in its deployed position.
Fig. 7 illustrates an alternate form of the blood clot filter shown in Fig. 1. The blood clot filter of Fig. 7 is designated generally by reference numeral 20', and like ~lood clot filter 20 of Fig. 1, includes a ~ose connector 40', a slid~ connector 42', a central core wire 26', and a number of peripheral wires connected ~etween ~05e ~onnector 40' and ~lide connector 42' to form a filter me~h 52'. The principal differences bet~een blood clot filter 20' o~ Fig.
7 and blood clot filter 20 of Fig. 1 relate to the formation of the leg assembly 51'. Whereas the leg portions shown in Fig. 1 are relatively ~traight and of uniform length, the le~ portions shown in Fig. 7 are both curved or bowed out~ardly and are of differing lengths.
The manner of delivçring blood clot filter 20 of Fig. 1 u~in~ a transfemoral approach ~ill now be described with reference to Fig~. 4A-4F wherein a novel filter delivery apparatus i~ shown. Fi~. 4A shows blood clot filter 20 in a compacted position received ~ithin the distal end 74 of a delivery catheter 70. Slide connector 42 of blood clot filter 20 is remote from no~e connector 40 to elongate 1 31 563~

filter mesh 52, and the hoo~sed elnd of the le$~ ~ortion~3 of peripheral wire~ 28-38 are compres~ed a~ain~t the lnterior wall 76 of delivery catheter 70. Not shown in Fig. 4A i~
the proxim~l end of delivery catheter 70 ~hi~h lies oppo~ite di~tal end 74 thereof. In~erted through the proximal end of delivery catheter 70 i~ a ~emi-rigîd pu~her catheter 80, the distal end 78 of which i~ visible in Fig.
4A. Not ~ho~n ~ithin Fis. 4A i8 ~he proximal end of pusher catheter 78 which extend~ from the proximal end of delivery catheter 70. Pu~her catheter 80 is slidingly recei~ed within delivery catheter 70, and the distal end 78 of pusher catheter 80 i~ adapted to abut hooked end portions 54-64 of peripheral wire~ 28-38.
Still referring to Fig. 4A, central core wire 26 i~
shown extending ~ithin the central bore 82 of pusher catheter 80 and is relea~ably coupled to a retractor cable 84 by a releasable coupling mechanism 86. Retractor cable 84 slidingly extend~ through bore 82 of pusher catheter 80.
Not shown in Fig. 4A is the proximal end of retractor cable 84 which extends outwardly from the proximal end of pu~her cable 80 so that it may be retracted and otherwise manipulated by a physician. Releasable coupling mechani~m 8S is required since retractor cable 84 must be disengaged from central core ~ire 26 of blood clot filter 20 once the blood clot filter has been properly positionad and deployed.
Referring briefly to Figs. 5A and 5~, releasable coupling mechanism 86 i8 ~ho~n a~ a cylindrical nub 88 secured ~o the end of central core ~ire 26, together with a slotted, cylindrical catch 90 secured to the distal end of retractor cable 84. Catch 90 has a diameter ~ommensurate with the diameter of the interior bore 82 of pu~her catheter 80. Catch 90 includes a lateral ~lot 92 having a depth and ~idth commensurate ~ith nub 88 ~or allowing nub 88 to be relea~ably captured therein~ In addition, a radial 810t 94 exte~d~ through the front face 96 of catch `- ao 131 563~
90 and extending to lRkeral ~lot 92 for permitting central core wir~ a6 to extend throuuh the front ace ~6 o~ catch 90. It ~hould be appreciated that when nub 8~ re~ts ~i hin catch 90, and ~hen catch 90 lie~ within pu~her catheter 80, central core ~ire a6 and retractor cable 84 ar~ ef~ectively secured together. Nowever, when it i~ de~ired tv di~engaye retractor cable B4 f rom central core wire 26, the u~er need only r~tract pusher catheter 80 and delivery catheter 70 for allowing catch 90 to di~engage nub 88.
An alternate relea~able coupling mechanism 86' i~ sho~n in Figs. 6A and 6B. ~ithin Fig. 6A, central core wire 26 may terminate in a looped connector 98 preferably having a width commensurate ~ith the internal diameter o~ bore 82 of pusher ~atheter 80. The distal end of retrActor cable 84 includes a hooked end 100, also having lateral dimensions commensurate with the internal diameter of bore 82 of pu~her catheter 80. Prior to delivery of the blo~d clot filter, hook 100 i5 inserted ~ithin looped ~onnector 98, ~hich remain engaged ~ith one another so long as they lie within bore 82 of pusher cathe~r 80. After the filter mesh of the blood clot filter has been deployed by retracting central core ~ire 26, both pusher catheter 30 and delivery catheter 70 can be retracted for permitting hooked end 100 of retractor cable ~4 to disengage looped connector 98 of central core ~ire 26.
Referring again to Fig. 4A, blood clot filter 20 i9 shown as being contained fully within distal end 74 of delivery catheter 70. Delivery catheter 70 may be, for example, a 10 or 12 French Teflon catheter, ~nd may be introduced into the blood vessel using the standard Selldinger angiographic technique. To position a flexible catheter within a blood vessel usîn~ the ~o-called Selldin~er techni~ue, a needle i5 first in erted into the blood ves~el, a guide wire is then threaded through the needle, and the needle i8 then ~ithdrawn leaving the guide ~ire in placQ.

, al 131 563~
DeliYery ~athet~r 70 i~ an o~en-en~ed catheter, an~
tapered, ~nu~-fittin~ ~n~io~r~phic c~th~ter (not ~hown) ma~
be inserted within delivery catheter 70 to ~acilitate the pas~age o~ delivery cathet~r 70 throu~h the bloo~ ve~el.
Delivery catheter 70 and the tapered angiographic catheter therein are the~ in~erted into the blosd ves~el over the guide wire. Delivery catheter 70 may be advanced throu~h the blood vessel until di~tal end 74 i~ approximately at the po~ition at which the blood clot filter 20 i5 to be delivered. ~ollowing placement o~ delivery ca~heter 70 within the blood vessel, the inner tapered angiographic catheter and ~uide wire are ~ithdrawn.
Fig. 19 illustrates a filter storage tube into whi~h blood clot filter 20 may be preloaded ~or being advanced into delivery catheter 70 after delivery catheter 70 has been placed within the blood vessel. ~ithin Fig. 19, delivery catheter 70 includes a female luer lock connector 300 at its proximal end. The ~ilter ~tor~ge tube is designated generally by reference numeral 302 and includes a short section of tubing 304 haYing approximately the ~ame internal diameter as delivery catheter 70. Shown within filter ~torage tube 304 i~ blood clot filter 20. A first end of filter storage tube 302 includes a male luer lock connector 306 adapted to scre~ onto female connector 300.
a5 The opposite end of ~ilter storage tube 304 is integrally joined ~ith a molded fitting 308 which includes a deformable elastomeric seal 310, as well as an infusion port 312. The distal end of pusher catheter 80 extends into ~ilter storage tube 302 through deformable seal 310, and retractor cable 84 extends within pusher catheter 80 and is coupled to ~ore ~ire 26 by reIea~able coupling mechanism 86. Once delivery catheter 70 has been adYanced into the blood ves~el so that it~ distal end i~ at the appropriate delivery site, an infusion line i~ connected to infusion port 312, and male luer connector 306 is then coupled to female luer connector 300. Pusher catheter 80 22 1 3 1 563~
an~ r~t~actor cable B4 ~r~ then adv~nce~ a~ a un$t to pu~h blood clot ~$1tQr 20 out of ~ilter ~torage tu~e 302 ~nd into delivery catheter 70. Pusher catheter 80 and r~tractor cable 84 are furth~r advanced until blood clot filter 20 ha~ been pu~hed to the di~tal end of delivery ~atheter 70. The remaining ~teps for ~eliverin~ blood clot filter 20 within the blood vessel are described below.
The next ~tep in deployin~ blood clot filter 20 i~ to partially retract delivery catheter 70 ~hile leaviny semi-rigid pusher catheter B0 fixed, un~il the distal end 74 ofdelivery ca~heter 70 has been retracted to approximately the location of ~lide connector 42. The natural springiness of the peripheral wire~ 28-34 of the filter me~h 52 cau~es each of the peripheral wires to move ~omewhat further apart from cen~ral core wire 26 as compared with their compacted ~onfiquration~ a3 shown in Fig. 4A. Turning to Fig. 4C, the next ~tep in deployin~ filter mesh 52 i~ to maintain the position~ of delivery catheter 70 and pusher catheter 80 fixed, with the hooked feet 54-60 of blood clot filter 20 abutting di~tal end 78 oP pusher catheter 80. The proximal end (not ~ho~n) of retractor cable 84 i8 then slo~ly retracted by the operator. As retractor cable 84 i~ retracted, relea~able coupling mechanism 86 causes central core ~ire 26 to be pulled to the left (relative to Fig. AC), as indicated by the arro~ desi~nated by reference numeral 104. ~hile central core wire 26 slidably extends through slide connector 42, central core ~ire 26 is ri~idly attached to no~e connector 40. Accordingly, a~ central core wire 26 i5 retracted, nose connector 40 al~o move~ to the left, a~
indicated by the arrow designated by reference numeral 106.
As no~e connector 40 i~ brough clo~er to ~lide connector 42, th2 peripheral wire~ making up ~ilter mesh 52 are each forced radially outward toward the inner wall~ 108 and 110 of the blood ves~el. Continued retraction of retractor cable 84 and central core ~ire 26, as shown in Fi~. 4D, ~" 23 1 ~1 563'~
causes filter me~h 52 ~o become fully ~eployed, ~ikh no~e connector 40 being po~itioned relatively proximate to ~lide connector 42. A3 ~hown in Fig. 4D, the outermo~t portions of ~ilter me~h 52 beco~e en~a~ed with interior wall~ 108 and 110 of the blood ves~el upon filter me~h 52 becomin~
fully deployed. A~ explained ~bove, slide connector 42 has a~sociated therewith ~ lock device which prevents central core wire 26 from later ~lidin~ to the ri~ht (relative to ~i~. 4D) through slide connector 42, and nose connector 40 iB thereby maintained closely proximate to ~lide connector 42.
The next step in deploying blood clo~ filter 20 i~ to further retract delivery catheter 70, as ~hown in Fi~. 4~, to expo~e the leg portions thereof and allow the same to sprin~ outward ~or allowing the hooked end~ thereof to engage internal walls 108 and 110 of the blood vessel as ~hown in Pig. 4~. The leg a~sembly 51 of blood clot filter 20 ~orms a filter in addition to filter mesh 52. Moreover, because blood clot filter 20 engages the i~ternal ~alls lOB
and 110 of the blood ves~el both alon~ the periphery of filter mesh 52 and the hooked end~ of the leg portions, blood clot filter 20 is positioned centrally along the lonsitudinal axi of the blood vesRel.
The last step in the delivery of blood clot filter 20 is shown in Fi~. 4F wherein both delivery catheter 70 and pusher catheter 30 are retracted, leaving only retractor cable 84 in the same position ~ho~n as in Fig. 4~.
Retraction of both delivery catheter 70 and pusher catheter 80 release~ couplin~ mechani~m 86 from i~ternal bore 82 o~
pusher catheter 80 and permits coupling mechanism 86 to be released from nub 88 of central of core ~ire 26. Retractor cable 84 i~ then retracted back within internal bore 82 of pu~her catheter 80, and the delivery sy~tem i5 then fully removed, leavin~ blood clot filter 20 properly po~itioned within the blood vessel at the desired location.
Fig~. lOA-lOC illustrate an alternate embodiment of the 1 ~1 563~, present invention includin~ a blood clot ~lter 1~0 de~igned ~or jugulAr delivery. AB ~ho~n in ~i~. lOA, blood clot filter 120 include~ a central core wire 126 havin~
fir~t and rigidly attached to a fir~t connector 140.
Central core ~ire 12~ extend~ along the central longitudinal axis of blood clot filter 120 ~nd pa~e~
through the central bore of a slide connector 142. A one-way lock washer 172, similar to that sho~n in Fig. 9, ha~ a central bore throu~h which core ~ire 126 extend~. Washer 172 is adapted to permit core wire 126 to slide therethrough to the right ~relative to Fig. lOA), but to resist sliding movement of central core wire 126 to the left. A plurality of peri~heral wire~, including those peripheral wire~ 128, 130, 132, and 134 vi~ible in 10~ each have a first end attached to qlide connector 142, and are each attached to connector 140. Peripheral wires 128-134 are shown in Fig. lOA in their compacted position loaded within a jugular delivsry cathe~er 170. ~ach of the peripheral wires 128-134 extend generally along and parallel to central core wire 126, a~ ~ho~n in Fig. lOA.
Also extendi~g to the left of connector 140 îs a leg a~sembly 141 con~i~ting of, for example, six ~ire legs, including tho~e visible in Fig. lOA and de~ignated by re~rence numeral~ 129, 131, 133, and 135. Each of ~uch leg~ 129-135 h ~ a first end secured to connector 140 and a 3econd end opposite thereto formed into hooked feet 154, 156, 158, and 160, respectively, for engaging fhe walls of a blood ve~sel into which blood clot filter 120 is to be positioned. As mentioned above, leg portion~ 129-135 may ~imply be continuations of the respective peripheral wires 128-134 which make up ~he filter mesh 152.
To deliver blood clot filter 120 u~ing the jugular delivery technique, ~elivery catheter 170 i~ introduced into the blood ve~el and advanced through the b~ood vessel until the distal end 174 of delivery catheter 170 is located at l 31 563~, approxi~ately the po~ition at which blood clo~ rilter 120 i~ to be deliver~d. Bloo~ clot ~llt~r 120 i~ po~itioned within the di~l end Or delivery cathet~r 170, a~ ~hown in Fig. lOA, either by puohin~ blood clot ~ er 120 along the len~th of delivery ~atheter 170 from the proximal end thereof, or by preloading blood clot filter 120 ~i~hin the di~tal end of d~livery ~atheter 170, in the manner de3cribed below. ~ithi~ Fig. lOA, ~emi-rigid pu~her catheter 180 i~ ~ho~n extending within the internal bore 176 of delivery catheter 170. Though not shown, the proximal end of pusher catheter 180 ~xtend3 fully throu~h the proximal end of deliverr ~atheter 170 ~o that it may be manipulat~d by a phyaician. Pu~her catheter 180 has a diameter commensurate ~ith that of one-~ay ~a~her 172, and the distal end of pusher ~atheter 180 is adapted to abut and push again~t ~asher 172. Central core wire 126 extends within internal bore 182 of pusher catheter 180 and is releasably con~ected ~ith releasable coupli~g mechani~m 186. The distal end of retractor cable 184 is also coupled to relea~able coupling mechanism 186. Retractor cable 184 extends fully through ~he internal bore 182 of pu~her catheter 180 and protrude~ from the proximal end thereof for allowing the physician to retract retractor cable 184.
~uring deli~ery of blood clot filter 120, delivery catheter 170 i8 retracted to the right, initially per~ittin~ leg~ 129-135 of leg as~embly 151 to spring outward, ~ith the hooked ends 154-160 thereof enga~ing the internal walls 208 and 210 of the blood ve~sel. Further retraction of delivery catheter 170 permita the peripheral wires 128-134 of filter mesh 152 to bow out~ardly, as shown in Yig. lOB.
The next step in deploying blood clot filter 120 i~ to advance pusher ~atheter 180 to the left, ~hile fixing the po~ition of retractor c~ble 184. It i~ important to fix the position of retractor ~able 184 to maintain ~onnector 140 in a fixed po~ition relative to the blood ves~el, and . ~

a6 131 563~
thereby avoid movement of hooked end~ 154-160, a~ ~uch longitudl~al ~ovement coulfl cauoe tr~u~ to the ~all~ 208 and 210 of the blood ves~el. A~ pusher c~theter 180 i~
advanced to the left, it advAnces washer 172 t~ the left alon~ central core wire 126. As washer 17~ advance~ to the left, it moves slide connector 142 into proximity with connector 140, thereby cau~ing peripheral ~ires 128-134 to beco~e radially extended to form filter mesh 152, as shown in Fig. lOC. When pu~her ca~heter 180 i~ fully advanced to the left, the outermo~t portion~ of filter me~h 152 engage the walls 208 and 210 of ~he blood vessel. Pusher catheter 180 i~ then retracted; as pusher ca~heter 180 i~ retracted, ~asher 172 become~ locked a~ainst central core wire 126 and thereby maintain~ filter meRh 152 ~ithin the deployed position ~hown in Fig. lOC. Both pusher catheter 180 and delivery catheter 170 are retr~cted ~o the righ~ (relative to ~ig. lOC) ~or exposing releasable coupling mechanism 186, thereby allowing central core 126 to be disengaged from retractor cable 1~4, as was de~cribed above in regard to Fig. 4~. Retractor cable 184, pusher catheter 180, and delivery catheter 170 may then be fully retracted, leaving blood clot filter 152 in ths de~ired location.
As explained abov0 with respect to Fig. 19, blood clot filter 20 can be loaded into the proximal end of delivery as catheter 70 using a filter ~torage tube that couples to the proximal end of delivery catheter 70. ~owever, blood clvt filter 20 must then be pushed along the delivery catheter to the distal end thereof; durin~ this procedure, the hooked ends of the blood clot filter legs scrape a~ainst the inner wall of the delivery catheter and could dislodge particles therefrom. In ordPr to avoid the need to push the blood clot filter alon~ the entire len~th of the delivery catheter, the alternate form of filter delivery system shown in Fig. 11 may be u~ed.
Within Fig. 11, blood clot filter 20 is of the same type sho~n in Fig. 1, and delivery catheter 270 i~ of 27 1 31 563'~
e~en~ially the ~ame type a~ delivery cathe~sr 70 o~ Fi~.
4A. Similarly, pu~h~r cathe~er 280 and retr~ctor c~ble 28~
corre~pond to the pusher Ga~heter 80 and retractor cable 84 sho~n in Fig. 4Ao ~o~ever, a~ ~hown in Fi~. 11, delivery catheter ~70 i~ inqerted through an outer catheter 275 which ha~ a di~tal end ~77 ~n~ a proximal end 279. The di~tal end a77 o outer catheter 275 i~ percutanesu~ly introduced into a blood ve~el u~ing the aforementioned Selldin~er technique prior to insertion o delivery catheter 270 therein. After outer catheter 275 i8 introduced ~ithin the blood vessel, delivery catheter 270 i~ inserted into outer catheter 275 from the proximal end 279 thereof. The proximal end 279 of outer catheter 275 includes a deformable ela~tomeric seal 281 which permits delivery catheter 270 ~o be ~lidingly received thereby while forming a fluid tight ~eal therearound. ~he proximal end 279 of outer catheter 275 also includes an infu~ion port A extending perpendicularly ~o the longitudinal axis of outer catheter 275 for permit~ing ~aline ~olution to be infused therei~, thereby preventing the patient's blood from filling the internal bore of outer catheter 275 and forming blood clots. Similarly, the proximal end 283 of delivery catheter 270 includes a deformable ela~tomeric seal 285 for ~lidingly receiving the di3tal end of pusher catheter 280 and forming a fluid ti~ht ~eal ~herearound.
The proximal end 283 of delivery catheter 270 al50 include~
an infusion port B into which saline 301ution may be infu~ed to prevent the patient'~ blood from collecting ~ithin the înternal bore of delivery catheter 270 and forming blood clots.
Similarly, pusher catheter 282 has a proximal end 287 provided with a deformable elastomeric ~eal 289 which slidingly receive~ the retractor cable 284 and form~ a fluid tight seal therearound. The proximal end 287 of pusher catheter 280 al90 include~ an infusion port C for i~fu~ion of ~aline ~olution to prevent the patient' 9 blood 1 31 563~

from colle~ting ~ithin the lntern~l bore o~ pusher c~thetex a80 an~ forming blood clot~. The proximal end of retractor cable a84 may include a down~ardly turned handle D ~or ~onveniant operation of retractor cable ~84.
The delivery ~ystem ~ho~n in Fig. 11 permits blood clot filter 20 to be preloaded into the di~tal end of delivery catheter 270 before delivery catheter 270 i~ in~erted into outer catheter 275. This i~ avoid3 the need to in~ert bloQd clot filter 20 into delivery catheter 270 from the proximal end thereof~ A~ shown in Fig. 11, a removable stop 291 may be relea~ably coupled, as by a clip (not ~hown~ to pusher catheter 280 for defining a fixed space or distance between infu~ion port C ~nd the leftmo~t end of ~top 291. The importance of the fixed ~pace created by stop 291 is explained in ~reater detail below in conjunction with Fig~. 12~15.
Figs. 12-15 illustrate, in ~chematic form, the series of steps followed in u~ing the delivery ~y~tem in Fig. 11. As shown in Fig. 12, blood clot filter 20 is initially dispo~ed in its compacted position, ~imilar to that sho~n in Fig. 11. In Fig. 13, both outer catheter 275 and delivery catheter 270 are retracted until infusioh port B
abut3 the leftmo~t end o~ stop 291. Similarly, outer catheter 275 i~ retracted until the proximal end 279 thereof abut~ infu~ion port B of delivery catheter 270.
Stop 291 i8 of a ~ufficient len~th to permit delivery catheter 270 and outer catheter 275 to be ~ithdrawn to the extent that the peripheral wires for~ing the ~ilter me~h are no lonqer encased by delivery catheter 270, while the le~ as~embly 51 of blood clot filter 20 remains encased by delivery ~atheter 270. As ~hown in Fig. 13, retractor cable 284 i~ then retracte~ whil0 holdi~g the proximal end 287 of pu~her ~atheter 280 fixed, thereby deploying filter mesh 52 of blood clot filter 20. The next ~tep involves removin~ ~top 291 and thereaf~er retracting both delivery catheter 270 and outer catheter 275 until the proximal end ~g ~ 3~ 563~
283 o~ delivery catheter a70 abut~ inu~io~ port C, and ~imilarly, the proximal end 279 of outer ~athe~er 275 abuta infu~ion port B, as sho~n in Fig. 14. Thi~ opera~io~
further retracts both the ~istal ends of delivery catheter 270 an~ outer catheter 275, thereby permitting leg a~embly 51 of blood clot filter 20 to ~pring out~ardly and en~age the walls of the blood ~e~el. Re~erring to FigA
15, the next ~tep of tlle operation i8 to retract pusher catheter 280, as well as deliver~ cathet r 270 and outer catheter 275, in order to permit the di~tal end of retractor cable 284 to be released from the central core wire of blood clot filter 20, as i~ indicated within Fig.
15. With blood clot filter ao then properly po~itioned, the entire delivery ~ystem is fully retracted out of the blood ve~el.
Yig. 20 illus rates a wire shapiny jig which may be used for pre-~haping each of the peripheral wires 28-38 shown in Figs. 1-3. As ~hown in Fi~. 20, the ~ire ~hapiny jig includes three circular pegs 320, 322, and 324. Peg~ 320 and 322 are spaced apart from one another by approximately the distance between second connector 42 and hooked end 54 ~hown in Fig. 1. Pegs 322 and 324 are spaced apart from another by approximately the di~tance sho~n between nose connector 40 and slide connector 42 shown in Fig. 4B. The wire shaping jig al80 includes a form 3Z6 having a ~emi-circular curved -~urface 328 adapted to advance between pegs 322 and 324. As ~hown in Yig. 20, peripheral wire 28 is placed against pegs 320, 322 and 324. Form 326 is then advanced against peripheral ~ire 28 and causing the same to be pu~hed through the space between pegs 322 and 324. Form 326 is further advan~ed until the curved surface 328 thereof is closely proximate pegs 322 and 324. The ends of peripheral wire 28 are then bent around peg~ 320 and 324.
The portion extendin~ beyond peg 320 is later clipped to form the hooked end 54 of the anchorin~ leg. Similarly, the portion extendi~g beyond peg 324 i~ l~ter clipped and 131~63~
attached to nose connector A0 o~ blood clot filt~r 2~.
~ ig~ 21 illu~rate~ ~n a~embly ji~ ~hich may ~e u~ed to ~upport the central core ~ire 26 centrally of the plurality of peripheral ~ire~ to facilitate the ~onnection of the peripheral wires about the central core ~ire. A~ ~ho~n in Fig. ~1, the mounting jig 330 is generally cone ~haped and includes a central bore 332 through which ~entral core ~ire 26 extends. A set of three scre~ 334, 336 and 333 threadedly en~age the cone ~haped mounting ji~. The ~lotted heads of screw~ 334, 336 and 338 may be slightly loos~ned for allo~ing the peripheral wire 28 to extend under su~h slotted heads. Screws 334, 336 and 338 are then tightened to hold peripheral wire 28 in place, ~ith the central bend thereof which ~as ~ormed about peg 322 (see Fi~. 20) positioned at the tip of the cone shaped jig 330.
Similarly, other ~ets of mountin~ ~cre~, ~uch as 340, 342 and 344 are also provided ~or releasably supporting ~he other peripheral wires, ~uch a~ peripheral wire 34. With all six ~ires secured to mounting jig 330 and spaced equiangularly about central core wire 26, it is relatively easy to weld or clip together the upper ends of the peripheral wires 28-38 with the upper end o central core ~ire 26, a~ within nose connector 40 (seP Fig. 1~. It is al~o then relatively ea~y to join together the peripheral wires at the upper tip of the cone-shaped ji~ 330, a~ with a ~lide connector 42 (~ee Fig. 1). As mentioned above, it may be desirable to rotate the nose connector throu~h an angle of 90-120a, and perhap~ to impart a heat treatment to the wire~ in order to pre-shape the filter mesh 90 that it will ~latten when the central core wire is retracted.
The aforementioned rotation of the nose connector may easily be performed before the central core wire 26 and peripheral ~ires 28-38 are removed from assembly jig 330.
The extra wire lengths extending below screw~ 336 and 342 may thereafter be clipped and the ends shaped to provide hooked ends on the end~ of the anchoring legs.

While the present invention ha~ been described in accordance with a pr~ferr~d embodiment thereo~, the de~cription i~ for illustrative purpose~ only and ~hould no~ be construed as limiting the scope of the invention.
Various changes and modifi~ation~ may be made by tho~e ~killed i~ the art without departing from the true spirit and s~ope of the invention as defined by the appended claims.

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Claims (19)

1. A blood clot filter comprising in combination:
a. a core wire extending along a central longitudinal axis of said blood clot filter;
b. a plurality of peripheral wires extending generally about and spaced around said core wire;
c. first connector means for connecting together said plurality of peripheral wires at a first connection point, said core wire lying within said plurality of peripheral wires at said first connection point, said first connector means fixedly securing said plurality of peripheral wires to said core wire lying therein;
d. second connector means for connecting together said plurality of peripheral wires at a second connection point spaced apart from said first connec-tion point, said core wire lying within said plurality of peripheral wires at said second connection point, said second connector means slidingly securing said plurality of peripheral wires about said core wire lying therein;
e. locking means permitting said second connector means to slide along said core wire in a first direction toward said first connector means from a first remote position to a second proximate position, said locking means preventing said second connector means from sliding along said core wire in a direction opposite to said first direction from said second proximate position back to said first remote position; and f. said plurality of peripheral wires each including a wire portion extending between said first and second connector means and lying generally along said core wire when said second connector means is in said first remote position, said wire portions moving radially away from said core wire to a deployed position for forming a generally flattened filter mesh as said second connector means advances to said second proximate position.

2. The blood clot filter recited by Claim 1 wherein each of aid plurality of peripheral wires includes a leg portion extending from one of said first and second connector means in a direction generally opposite to the other of said first and second connector means, each of said leg portions being biased away from the central longitudinal axis of said blood clot f filter, each of said leg portions having a foot at an end thereof for engaging an interior wall of a blood vessel to maintain said blood clot filter at a desired location within said blood vessel, and to maintain said blood clot filter centered within said blood vessel.

3. The blood clot filter recited by Claim 2 including spreader means disposed between said leg portions and said core wire for biasing said leg portions away from the central longitudinal axis of said blood clot filter.

4. The blood clot filter recited by Claim 1 further including a plurality of legs spaced about said core wire, each of said legs having a first end coupled to one of said first and second connector means and a second end opposite the first end, the second end of each of said plurality of legs having a foot for engaging an interior wall of a blood vessel to maintain said blood clot filter at a desired location within said blood vessel, and to maintain said blood clot filter centered within said blood vessel .

5 . The blood clot filter recited by Claim 4 including spreader means disposed between said plurality of legs and said core wire for biasing said leg portions away from the central longitudinal axis of said blood clot filter.

6. The blood clot filter recited by Claim 1 wherein said second connector means comprises a sleeve through which said core wire extends, said sleeve having an exterior circular wall, and each of said plurality of peripheral wires being connected to said exterior circular wall.

7. The blood clot filter recited by Claim 1 wherein said second connector means comprises a collar having a central opening, each of said plurality of peripheral wires extending through the central opening of said collar and being secured to said collar.

8. The blood clot filter recited by Claim 1 wherein:
a. said core wire extends between first and second opposing ends;
b. said first connector means joining said plurality of peripheral wires together and fixedly securing the first end of said core wire thereto; and c. a plurality of legs extend from said second connector means generally toward the second end of said core wire and spaced about said core wire, each of said legs having a first end coupled to said second connector means and a second end opposite the first end, the second end of each of said plurality of legs having a foot for engaging an interior wall of a blood vessel to maintain said blood clot filter at a desired location within said blood vessel, and to maintain said blood clot filter centered within said blood vessel.

9. The blood clot filter recited by Claim 8 wherein the second end of said core wire extends beyond the second ends of said plurality of legs and terminates in a retractor fitting for releasably engaging a retractor to pull said first connector means toward said second connector means as said core wire slides through said second connector means.

10. The blood clot filter recited by Claim 1 wherein:
a. said core wire extends between first and second opposing ends;
b. said first connector means joining said plurality of peripheral wires together and fixedly securing the same to the first end of said core wire; and c. a plurality of leg extend from said first connector means generally away from the second end of said core wire and spaced about said core wire, each of said legs having a first end coupled to said first connector means and a second end opposite the first end, the second end of each of said plurality of legs having a foot for engaging an interior wall of a blood vessel to maintain said blood clot filter at a desired location within said blood vessel, and to maintain said blood clot filter centered within said blood vessel.

11. The blood clot filter recited by Claim 8 wherein the wire portion extending between said first and second connector means for each of said plurality of peripheral wires is of a predetermined length, and wherein said core wire is of a length greater than said predetermined length, the second end of said core wire terminating in a retractor fitting for releasably engaging a retractor to maintain said first connector means fixed while said second connector means is advanced toward said first connector means by sliding said second connector means along said core wire.

12. The blood clot filter recited by Claim 1 wherein said plurality of peripheral wires includes at least six peripheral wires spaced substantially equiangularly about said core wire.

13. The blood clot filter recited by Claim 1 wherein said core wire and said plurality of peripheral wires are made of stainless steel.

14. The blood clot filter recited by Claim 1 wherein said core wire and said plurality of peripheral wires are made of titanium.

15. The blood clot filter recited by Claim 1 wherein the thicknesses of said peripheral wires forming said filter mesh are each approximately 0.010 inch.

16. The blood clot filter recited by Claim 1 wherein the flattened filter mesh formed by said plurality of peripheral wires extends generally perpendicular to the central longitudinal axis of said blood clot filter.

17. In combination, a blood clot filter and a filter delivery apparatus, wherein:
a. said blood clot filter comprises in combination:
i. a core wire extending along a central longitudinal axis of said blood clot filter and including first and second opposing ends;
ii. a plurality of peripheral wires extending generally about and spaced around said core wire;
iii. a first connector for connecting together aid plurality of peripheral wires at a first connection point, said core wire lying within said plurality of peripheral wires at said first connection point and fixedly securing said plurality of peri-pheral wires to the first end of said core wire;
iv. a second connector for connecting together said plurality of peripheral wires at a second connection point spaced apart from said first connection point and slidingly securing said plurality of peripheral wires about said core wire lying therein;
v. locking means permitting said second connector to slide along said core wire from a first remote position to a second proximate position, said locking means preventing said second connector from sliding along said core wire from said second proximate position back to said first remote position; and vi. said plurality of peripheral wires each including a wire portion extending between the first and second connectors and lying generally along said core wire when said second connector is in said first remote position, said wire portions moving radially away from said core wire to a deployed position for forming a generally flattened filter mesh as said second connector advances to its second proximate position;
b. said filter delivery apparatus comprises in combination:
i. a delivery catheter having a distal end for percutaneous introduction into a blood vessel and having a proximal end opposite the distal end thereof, the distal end of said delivery catheter being adapted to receive said blood clot filter for positioning the same at a desired location in a blood vessel;
ii. a pusher catheter slidingly received within said delivery catheter and having a distal end proximate the distal end of said delivery catheter, said pusher catheter having a proximal end extending from the proximal end of said delivery catheter, the distal end of said pusher catheter abutting said blood clot filter for advancing the same out of the distal end of said delivery catheter; and iii. a retractor cable slidingly extending through said pusher catheter, said retractor cable having a proximal end extending outwardly from the proximal end of said pusher catheter and having a distal end releasably coupled to the second end of said core wire of said blood clot filter for retracting said core wire after said blood clot filter is at least partially advanced from the distal end of said delivery catheter while said pusher catheter remains in abutting relationship with said blood clot filter for causing said plurality of peripheral wires to form said filter mesh.

18. The combination recited in Claim 17 wherein said filter delivery apparatus further includes an outer catheter having a distal end for percutaneous introduction into a blood vessel and having a proximal end opposite to the distal end thereof, said outer catheter slidingly receiving said delivery catheter for allowing said blood clot filter to be delivered thereby, said outer catheter including an entrance port at the proximal end thereof, said entrance port including a deformable seal for sealing the proximal end of said outer catheter while permitting the distal end of said delivery catheter to be removably inserted therethrough.

19. The combination recited in Claim 17 wherein each of said plurality of peripheral wires includes a leg portion extending from one of said first and second connectors in a direction generally opposite to the other of said first and second connectors, each of said leg portions being biased away from the central longitudinal axis of said blood clot filter, each of said leg portions having a foot at an end thereof for engaging an interior wall of a blood vessel to maintain said blood clot filter at a desired location within said blood vessel.