US20100228281A1

Movatterモバイル変換

Info

Publication number: US20100228281A1
Application number: US12/688,173
Authority: US
Inventors: Paul Gilson; Steven Horan; Karl KEATING; Aidan Goggin
Original assignee: Individual
Current assignee: Boston Scientific Medical Device Ltd; Covidien Group SARL
Priority date: 2009-01-16
Filing date: 2010-01-15
Publication date: 2010-09-09
Also published as: US11672641B2; US20170340429A1; US20200197150A1; EP2381892A1; EP2381892B1; US10624731B2; WO2010082189A1

Abstract

A vascular filter system comprises a vascular filter (1), a clamp device (50), and a delivery catheter (51). The filter (1) comprises filter elements (6). When used without the clamp device (50), the filter elements (6) move from a closed state to an open state upon elapse of a predetermined period of time. In the closed state the filter elements (6) capture thrombus passing through the inferior vena cava (2). The delivery catheter (51) is employed to deliver the clamp device (50) to the filter (1) after the filter (1) has been deployed in the inferior vena cava (2). The clamp device (50) engages with the filter elements (6) of the filter (1) to clamp the filter (1) in the closed state beyond elapse of the predetermined period of time. Because of the presence of the clamp device (50), the filter elements (6) are no longer free to move from the closed state to the open state upon elapse of the predetermined period of time. In this manner the period of time in which the filter (1) captures thrombus is extended either temporarily or permanently.

Description

RELATED APPLICATIONS

This application claims the benefit of priority from U.S. Provisional Application No. 61/145,387 filed on Jan. 16, 2009, the entire contents of which are incorporated herein by reference.

INTRODUCTION

This invention relates to a vascular filter system.

WO2008/010197 describes a vascular filter having filter elements which are held by a holder in a closed state for capturing thrombus passing through a blood vessel. The filter opens when the holder biodegrades after a predetermined period of time.

The invention is directed towards providing more versatility in use of a filter after delivery.

SUMMARY OF THE INVENTION

According to the invention, there is provided a vascular filter system comprising a vascular filter comprising at least one filter element, the filter being movable from a closed state for capturing thrombus passing through a blood vessel to an open state facilitating unrestricted blood flow. There may be a holder for holding the filter in the closed state for a predetermined period of time. There may be a member to at least temporarily extend the filtration period.

In one embodiment, the member comprises a retainer to at least temporarily retain the filter in the closed state beyond elapse of the predetermined period of time.

In one embodiment, the retainer is extendable around at least part of the filter to retain the filter in the closed state. In one embodiment, the retainer is adapted to clamp at least part of the filter to retain it in the closed state. In one embodiment, the retainer is adapted to tie at least part of the filter to retain it in the capturing state. In one embodiment, the retainer is configured to be located in the region of the centre of the filter. In one embodiment, the retainer is configured to be located in the region of the side of the filter. In one embodiment, at least part of the retainer is biodegradable and/or bioabsorbable. In one embodiment, the retainer is biostable. In one embodiment, the retainer is movable between a delivery state and a retaining state.

In one embodiment, the retainer comprises first magnetic parts on the filter elements and a second magnetic part for engagement with the first magnetic parts to retain the filter elements in the closed state. In one embodiment, the first magnetic parts are located on the filter elements so that they are in a plane when the filter is in the closed state, and the second magnetic part has a planar face for contacting the first magnetic parts. In one embodiment, the second magnetic part is annular or disc-shaped.

In one embodiment, the system comprises a delivery assembly including a delivery catheter having a magnetic attraction to the second magnetic part which is less than the magnetic attraction between the first magnetic parts and the second magnetic part.

In one embodiment, the second magnetic part is sleeve-shaped, and the first magnetic parts are arranged in a ring which fits within the sleeve when the filter is in the closed state.

In one embodiment, the retainer is cup-shaped and configured to snap-fit around the ends of the filter elements. In one embodiment, the filter elements have arrow-shaped tips to fit behind a rim of the retainer. In one embodiment, the filter is biased towards the open state.

In one embodiment, at least part of the retainer is extendable through an opening between adjacent filter elements to retain the filter elements in the closed state beyond elapse of the predetermined period of time.

In one embodiment, at least part of the retainer is extendable through an opening in a filter element to retain the filter elements in the closed state beyond elapse of the predetermined period of time.

In one embodiment, in the closed state the filter elements extend towards an apex. In one embodiment, the retainer is configured to be located in the region of the apex. In one embodiment, the retainer is configured to be located in the region of the end of the filter element opposite to the apex.

In one embodiment, at least part of the holder is biodegradable and/or bioabsorbable upon elapse of the predetermined period of time.

In one embodiment, the filter comprises a vena cava filter.

In another aspect, the invention provides a method for treating a blood vessel, the method comprising the steps of:

- locating a vascular filter in the blood vessel, the vascular filter comprising at least one filter element, the filter being movable after a predetermined period of time from a closed state for capturing thrombus passing through the blood vessel to an open state facilitating unrestricted blood flow, and
- a retainer at least temporarily retaining the filter in the capturing state beyond elapse of the first predetermined period of time.

In one embodiment, the method comprises the step of delivering the retainer to the filter. In one embodiment, the retainer is delivered to the filter after the filter has been located in the blood vessel. In one embodiment, the retainer is delivered to the filter using a delivery mechanism, and the method comprises the step of centering the delivery mechanism in the blood vessel. In one embodiment, the method comprises the step of maintaining the position of the filter relative to the blood vessel during delivery of the retainer.

In one embodiment, the method comprises the step of grasping the filter before delivering the retainer. In one embodiment, the method comprises the step of changing the retainer while it engages the filter from a non-retaining state in which the filter is not retained to a retaining state in which the filter is retained.

In one embodiment, the retainer is changed from the non-retaining state to the retaining state by external intervention. In one embodiment, the retainer is moved with respect to the filter.

In one embodiment, the retainer is rotated to move on threads. In one embodiment, the retainer is pushed or pulled with respect to the filter.

In one embodiment, the intervention includes inserting a retainer magnetic part for retaining the filter elements in the closed state. In one embodiment, the method comprises the step of extending the retainer around at least part of the filter. In one embodiment, at least part of the retainer biodegrades and/or is bioabsorbed upon elapse of a second predetermined period of time. In one embodiment, the method comprises the step of removing the retainer from the filter.

A vascular system configured to replace bioresorbable materials in vascular devices with a biostable component.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more clearly understood from the following description of some embodiments thereof, given by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 is a side view of a vascular filter part of a vascular filter system according to the invention located in a blood vessel,

FIGS. 2 to 8 are side views of the vascular filter part ofFIG. 1 in use in the blood vessel,

FIG. 9 is an isometric view of a retaining means part of the vascular filter system according to the invention in a delivery configuration,

FIG. 10 is an isometric view of the retaining means part ofFIG. 9 in a retaining configuration,

FIGS. 11 to 18 are cross sectional side views of the vascular filter part ofFIG. 1 and the retaining means part ofFIG. 9 in use,

FIGS. 19 and 20 are views similar toFIGS. 9 and 10 of a retaining means part of another vascular filter system according to the invention,

FIGS. 21 and 22 are views similar toFIGS. 9 and 10 of a retaining means part of another vascular filter system according to the invention,

FIGS. 23 and 24 are views similar toFIGS. 9 and 10 of a retaining means part of another vascular filter system according to the invention,

FIG. 25 is a view similar toFIG. 18 of another vascular filter system according to the invention in use,

FIGS. 26 to 29 are views similar toFIGS. 11 to 13(b) of another vascular filter system according to the invention in use,

FIGS. 29(a) to29(d) are views similar toFIGS. 11 to 13(b) of another vascular filter system according to the invention in use,

FIGS. 29(e) to29(g) are views similar toFIGS. 14 to 18 of another vascular filter system according to the invention in use,

FIG. 29(h) is an isometric view of a vascular filter part of another vascular filter system according to the invention,

FIG. 29(i) is a cross sectional side view of the vascular filter system according to the invention in use,

FIG. 29(j) is a side view of the vascular filter system ofFIG. 29(i),

FIG. 29(k) is an end view of the vascular filter system ofFIG. 29(i),

FIG. 29(l) is a side view of another vascular filter system according to the invention in a non-retaining configuration,

FIG. 29(m) is an isometric view of the vascular filter system ofFIG. 29(l) in a retaining configuration,

FIG. 29(n) is an isometric view of a vascular filter part of another vascular filter system according to the invention,

FIG. 29(o) is an isometric view of a retaining means part of the vascular filter system according to the invention,

FIG. 29(p) is a cross sectional side view of the vascular filter part ofFIG. 29(n) and the retaining means part ofFIG. 29(o),

FIGS. 30 to 32 are views similar toFIGS. 11 to 13(b) of another vascular filter system according to the invention in use,

FIG. 33 is an end view of a vascular filter part of the vascular filter system ofFIGS. 30 to 32,

FIGS. 34 to 37 are views similar toFIGS. 11 to 13(b) of a retaining means part of the vascular filter system ofFIGS. 30 to 32 in use,

FIG. 37(a) is an isometric view of a retaining means part of another vascular filter system according to the invention,

FIGS. 38 to 41 are views similar toFIGS. 11 to 13(b) of another vascular filter system according to the invention in use,

FIG. 42 is an isometric view of a retaining means part of the vascular filter system ofFIGS. 38 to 41,

FIG. 43 is a side view of a retaining means part of another vascular filter system according to the invention,

FIGS. 44(a) to44(d) are side views of retaining means parts of other vascular filter systems according to the invention,

FIG. 45 is an isometric view of a vascular filter part of another vascular filter system according to the invention,

FIGS. 46 and 47 are isometric views of part of the vascular filter part ofFIG. 45,

FIG. 48 is an isometric view of the vascular filter part ofFIG. 45 and a retaining means part of the vascular filter system before elapse of a predetermined period of time,

FIG. 49 is an isometric view of the vascular filter part ofFIG. 45 and the retaining means part ofFIG. 48 after elapse of the predetermined period of time,

FIGS. 50 and 51 are views similar toFIGS. 11 to 13(b) of another vascular filter system according to the invention in use,

FIGS. 52 to 55 are isometric views of the vascular filter system ofFIGS. 50 and 51 in use,

FIG. 56 is a cross sectional side view of another vascular filter system according to the invention,

FIGS. 57 to 59 are views similar toFIG. 56 of other vascular filter systems according to the invention,

FIG. 60 is a perspective view of a filter with magnetic retainer elements, and

FIG. 61 shows the filter in more detail together with a second magnetic part delivered by a catheter, and

FIG. 62 shows delivery of the second retainer part;

FIG. 63 is a side view of a further filter of the invention, and

FIG. 64 shows delivery of a sleeve-shaped magnetic retainer by a catheter;

FIG. 65 is a set of views showing an alternative filter of the invention onto which a cup-shaped retainer is placed by a catheter; and

FIG. 66 is a set of views showing the filter elements and the retainer in more detail.

DETAILED DESCRIPTION

Referring to the drawings, and initially toFIGS. 1 to 18 thereof, there is illustrated a vascular filter system according to the invention. The vascular filter system comprises avascular filter1, aretainer10, and adelivery catheter11.

Thevascular filter1 is suitable for use as an inferior vena cava filter in theinferior vena cava2. When used without theretainer10, thefilter1 is movable from a closed state (FIG. 4) to an open state (FIG. 7) upon elapse of a predetermined period of time. In the closed state thefilter1 captures thrombus passing through theinferior vena cava2 towards the heart and the lungs (FIG. 5). Thefilter1 may thus be used to prevent pulmonary embolism. In the open state thefilter1 facilitates unrestricted blood flow.

As illustrated inFIG. 1, thefilter1 comprises aproximal support hoop3 at the proximal end of thefilter1, adistal support hoop4 at the distal end of thefilter1, and a plurality of support struts5 extending between theproximal support hoop3 and thedistal support hoop4.

In this patent specification, the terms ‘proximal’ and “distal” are used in the sense that a proximal part is upstream of a distal part with reference to the direction of blood flow.

Theproximal support hoop3 comprises a wire element which extends circumferentially around the internal wall of theinferior vena cava2 in a sinusoid wave pattern. Similarly thedistal support hoop4 comprises a wire element which extends circumferentially around the internal wall of theinferior vena cava2 in a sinusoid wave pattern. The support struts5 extend longitudinally along the internal wall of theinferior vena cava2. The support struts5 connect theproximal support hoop3 to thedistal support hoop4. In this case theproximal support hoop3, thedistal support hoop4 and the support struts5 are formed integrally. Theproximal support hoop3, thedistal support hoop4 and the support struts5 may be of a shape-memory material, such as Nitinol™.

As illustrated inFIG. 1, thefilter1 comprises twelvefilter elements6 for capturing thrombus passing through theinferior vena cava2. Eachfilter element6 is formed integrally with theproximal support hoop3.

In the closed state thefilter elements6 extend in a substantially straight line to an apex7, where thefilter elements6 engage each other. In this manner thefilter elements6 define a generally conically shapedcapture region8 within which thrombus may be captured. When thefilter1 is deployed in theinferior vena cava2, theapex7 is substantially in-line with the longitudinal axis extending through the centre of theinferior vena cava2, and thecapture region8 is located in the region of the centre of theinferior vena cava2. When thefilter1 is deployed in theinferior vena cava2, thefilter elements6 extend in the direction of blood flow through theinferior vena cava2.

The distal end of thedistal support hoop4 is located distally of thefilter elements6 and the apex7, and the proximal end of theproximal support hoop3 is located proximally of thefilter elements6.

When used without theretainer10, thefilter elements6 are movable from the closed state to the open state upon elapse of the predetermined period of time. Thefilter elements6 are biased towards the open state, and a holder is provided at the distal ends of thefilter elements6 to temporarily hold thefilter elements6 in the closed state until elapse of the predetermined period of time. The holder is biodegradable and/or bioabsorbable upon elapse of the predetermined period of time. When used without theretainer10, upon biodegrading/bioabsorbing of the holder, thefilter elements6 are free to move from the closed state to the open state. Thefilter elements6 are not biodegradable or bioabsorbable.

The holder may be provided in the form of a holder tube, or alternatively in the form of a holder suture extended through an opening at the distal end of each of thefilter elements6.

Thefilter1 is movable between a collapsed delivery state and an expanded deployed state. Thefilter1 is biased radially outwardly towards the deployed state. When thefilter1 is deployed in theinferior vena cava2, the

support hoops

3,4 exert a force radially outwardly on the internal wall of theinferior vena cava2. In this manner the

support hoops

3,4 support thefilter elements6 in position relative to the wall of theinferior vena cava2.

Theretainer10 acts to at least temporarily retain thefilter1 in the closed state beyond elapse of the predetermined period of time.

In this case theretainer10 is provided in the form of a clamp tube. Theclamp tube10 is movable between a delivery state (FIG. 9) and a retaining state (FIG. 10). Theclamp tube10 is biased towards the retaining state.

In the retaining state theclamp tube10 extends around the distal ends of thefilter elements6 of thefilter1 to retain thefilter1 in the closed state (FIG. 13(b)) beyond elapse of the predetermined period of time. In particular, in the retaining state theclamp tube10 engages with thefilter elements6 of thefilter1 to clamp thefilter1 in the closed state. In the retaining state theclamp tube10 is located in the region of theapex7 of thefilter1 at the centre of thefilter1.

Because of the presence of theclamp tube10, thefilter elements6 are no longer free to move from the closed state to the open state upon elapse of the predetermined period of time. Upon biodegrading/bioabsorbing of the holder, thefilter elements6 of thefilter1 are retained in the closed state by theclamp tube10. In this manner the period of time in which thefilter1 captures thrombus is extended either temporarily or permanently.

Theclamp tube10 may be biodegradable and/or bioabsorbable. This results in a temporary extension of the period of time in which thefilter1 may capture thrombus. Alternatively theclamp tube10 may be biostable. This results in a permanent extension of the period of time in which thefilter1 may capture thrombus. Thetemporary filter1 may be converted into a permanent filter, or the life of thefilter1 may be prolonged.

Aninclined lip12 is provided at the distal end of eachfilter element6. Thelips12 are engagable with theclamp tube10 in the retaining configuration to releasably couple theclamp tube10 in position around the distal ends of thefilter elements6 of the filter1 (FIG. 13(b)).

As illustrated inFIGS. 14 to 18, thelips12 may be invertable to facilitate selective removal of theclamp tube10 from the distal ends of thefilter elements6 of thefilter1.

Thedelivery catheter11 is employed to deliver theclamp tube10 to thefilter1 after thefilter1 has been deployed in theinferior vena cava2. Thedelivery catheter11 comprises aninner tube15 upon which theclamp tube10 is mounted in the delivery configuration, anouter sheath14, apusher member13 intermediate theinner tube15 and theouter sheath14, and agrasping wire16 for grasping the distal ends of thefilter elements6 of thefilter1. The graspingwire16 may be used to maintain the position of thefilter1 relative to theinferior vena cava2 during delivery of theclamp tube10. Arecess17 is provided at the proximal end of theinner tube15 to facilitate positioning of theclamp tube10 around the distal ends of thefilter elements6 of the filter1 (FIG. 12).

In use, thefilter1 is collapsed to the delivery state, and at least partially loaded into a delivery catheter. The delivery catheter is advanced through theinferior vena cava2 until thecollapsed filter1 reaches the desired location in the inferior vena cava2 (FIG. 2). A restraining sheath of the delivery catheter is then moved relative to thefilter1 to fully uncover the filter1 (FIG. 3). Due to the biasing nature of thefilter1, thefilter1 moves from the collapsed delivery state to the expanded deployed state (FIG. 4). In the deployed state, the

support hoops

3,4 exert a radially outward force on the internal wall of theinferior vena cava2 to support thefilter elements6 in the desired position in theinferior vena cava2.

In the event of thrombus passing through theinferior vena cava2 towards the heart and the lungs, the thrombus will be captured in thecapture region8 of the filter1 (FIG. 5). The thrombus will thus be prevented from passing into the heart and the lungs which could otherwise lead to pulmonary embolism. The captured thrombus will gradually be broken down by the body into smaller size particles which will significantly reduce the risk of embolism (FIG. 6).

The holder temporarily holds thefilter elements6 in the closed state until elapse of the predetermined period of time. Before elapse of the predetermined period of time, theclamp tube10 is mounted in the delivery state on theinner tube15 of thedelivery catheter11. Thedelivery catheter11 is advanced through theinferior vena cava2 until theclamp tube10 reaches the distal ends of thefilter elements6 of thefilter1, which has previously been deployed in the inferior vena cava2 (FIG. 11). The graspingwire16 is looped around the distal ends of thefilter elements6 of thefilter1 to hold thefilter1 relative to thedelivery catheter11 and to maintain the position of thefilter1 relative to the inferior vena cava2 (FIG. 11). Theouter sheath14 is retracted to uncover the clamp tube10 (FIG. 12). Thedelivery catheter11 is advanced further through theinferior vena cava2 until thelips12 are within the recess17 (FIG. 12). Thepusher member13 is moved proximally relative to theinner tube15 until theclamp tube10 is positioned around the distal ends of thefilter elements6 of thefilter1. Due to the biasing nature of theclamp tube10, theclamp tube10 moves from the delivery state to the retaining state (FIG. 13(a)).

In the retaining state theclamp tube10 engages with thefilter elements6 of thefilter1 to clamp thefilter1 in the closed state beyond elapse of the predetermined period of time. Upon elapse of the predetermined period of time the holder biodegrades/bioabsorbs. Thefilter elements6 of thefilter1 are retained in the closed state by theclamp tube10. In this manner the period of time in which thefilter1 captures thrombus is extended either temporarily or permanently.

In the case where theclamp tube10 is biodegradable and/or bioabsorbable, theclamp tube10 biodegrades/bioabsorbs upon elapse of a further predetermined period of time. This enables thefilter elements6 to move from the closed state to the open state (FIG. 7). In the open state thefilter1 facilitates unrestricted blood flow. The

support hoops

3,4 and thefilter elements6 remain in the inferior vena cava2 (FIG. 8).

In the case where theclamp tube10 is biostable, thefilter1 is permanently retained in the closed state (FIG. 6).

In the case of either the biodegradable/bioabsorbable clamp tube10 or the biostable clamptube10, to remove theclamp tube10 from the distal ends of thefilter elements6 of thefilter1, the graspingwire16 is looped around the proximal end of the clamp tube10 (FIG. 15). The graspingwire16 is moved distally relative to thefilter1 to draw theclamp tube10 distally causing inversion of the lips12 (FIG. 16), and removal of theclamp tube10 from the distal ends of thefilter elements6 of the filter1 (FIG. 17). If theclamp tube10 is removed after elapse of the predetermined period of time, thefilter elements6 move from the closed state to the open state (FIG. 7). In the open state thefilter1 facilitates unrestricted blood flow. The

support hoops

3,4 and thefilter elements6 remain in the inferior vena cava2 (FIG. 8).

FIG. 11 illustrates the lasso/snare16 threaded over thehooks12 and tightened. Once thehooks12 enter thehook dock17 which occurs during tightening and prevents thebiostable ring10 from being deployed over thehooks12, thesnare16, the centringshaft15, and theouter sheath14 are held stationary while thepusher13 is advanced to deploy thebiostable ring10 between theimplant filtration elements6 and thehooks12.

FIGS. 12 and 13(a) illustrate thebiostable ring10 moving from the undeployed expanded state to the deployed contracted state. The centringshaft15 holds thebiostable ring10 in the expanded state during delivery. Once thepusher13 advances thebiostable ring10 proximal of the centringshaft15, thebiostable ring10 reverts to its natural contracted state. This phase transition may be achieved through the use of a spring or shape memory material

It may be desirable to remove thebiostable ring10 once the patient has fully recovered (FIG. 17). This can be achieved through the use of thesnare16.

In order to prevent complications arising from thebiostable ring10 flowing loose in the venous system, a catch may be employed to aid retrieval of the biostable ring10 (FIG. 18). The catch feature may be in the form of a retrieval catheter housed over thesnare device16 consisting of an expandable tip.

It will be appreciated that the retainer may be provided in any suitable form, for example a tubular mesh20 (FIGS. 19 and 20), or a coil21 (FIGS. 21 and 22), or a cut tube22 (FIGS. 23 and 24).

Theretainer30 may comprise anengagable protrusion31 around which thegrasping wire16 may be looped to assist removal of theretainer30 from the distal ends of thefilter elements6 of the filter1 (FIG. 25). The catch feature may be in the form of thehook31 connected/formed as part of thering30. This embodiment may also encompass a receiver mouth on the distal end of the snare catheter to facilitate removal of thebiostable ring30.

InFIGS. 26 to 29 there is illustrated another vascular filter system according to the invention, which is similar to the vascular filter system ofFIGS. 1 to 18, and similar elements inFIGS. 26 to 29 are assigned the same reference numerals.

In this case theretainer40 is provided in the form of a clamp tube. Theclamp tube40 has the same configuration both during delivery (FIG. 26) and during retaining (FIG. 29).

As illustrated inFIG. 28, thelips12 are deformable to facilitate location of theclamp tube40 around the distal ends of thefilter elements6 of thefilter1.

The graspingwire16 may be used to maintain the position of thefilter1 relative to theinferior vena cava2 during delivery of theclamp tube40. In use, the graspingwire16 is looped around the distal ends of thefilter elements6 of thefilter1 to hold thefilter1 relative to thedelivery catheter11 and to maintain the position of thefilter1 relative to the inferior vena cava2 (FIG. 27). In order to prevent the support rings3,4 and barbs from being pulled distally or pushed proximally or vice versa depending on the direction of approach of thedelivery catheter11, thedelivery mechanism11 is provided in such a way as to balance the forces applied to thefilter elements6. For example, when pushing theclamp tube40 over the apex endings, a simultaneous pull force is applied to the hook integral with thefilter elements6. The push force is applied with thepusher13, and the pull force is applied with thesnare16. This force balancing may be incorporated into any of the embodiments disclosed herein from a proximal or distal approach. This arrangement prevents damage to the vessel wall during application of thesecondary restraint40.

The snare/lasso16 is threaded over the distal hooks and tightened (FIG. 27). This centres theconversion catheter assembly11 and holds theimplant filtration elements6 stationary while thebiodegradable conversion ring40 is translated over theretainers12. Once tightened, the proximal end of thesnare16 and the snareouter tube14 are held stationary while thepusher13, and theextension ring40 are advanced until theextension ring40 is locked in position between the two sets ofretainers12.

The tip of theouter sheath14 may encompass an expandable tip that allows theextension ring40 to be advanced through it with force but not without force. This serves as a safety feature preventing theextension ring40 from being detached prematurely.

The invention enables thefilter1 to be converted into a permanent filter if the indications for the patient changed or were incorrectly assessed at the time of implant. A means of achieving this is to use a catheter to place a cap, tie or other locking mechanism at theapex7 of thefilter1 to hold theconvertible filter elements6 in the filter configuration permanently. This may be achieved using thecatheter11 which gains access to the venous system by percutaneous access and delivers thelocking mechanism40 to the filter site.

The hook is incorporated into theapex region7 which may be engaged with thesnare component16 that is delivered from the distal side of the filter1 (FIGS. 26 to 29). Snaring the hook allows thecatheter11 to be positioned accurately at theapex7 of thefilter1. Thecatheter11 houses the fixingcomponent40 to convert thefilter1 into a permanent device.

Once the hook is engaged and thesnare16 retracted, theouter tube14 can be slid over the apex region, this will ensure good alignment and minimise any risk of the fixingcomponent40 becoming an embolus. The fixingcomponent40 is then pushed forward and released so that it engages theapex region7 of thefilter1 constraining thefilter elements6 of thedevice1 so that they cannot return to the vessel wall. The distal end of theapex region7 includes thefeature12 that prevents the fixingcomponent40 moving distally.

In order for the fixingcomponent40 to engage in its final position it needs to navigate past thisfeature12. This could be achieved by designing thecomponent40 to be held at a larger diameter in thecatheter11 but once it is released it springs back to a smaller diameter engaging with thefilter1 sufficiently to achieve a permanent attachment. Means of achieving this could be by using a coiled spring, a lattice or trellis type arrangement, or by using a slit tube. The fixingdevice40 may also be inherently flexible to be pushed over the snapfit feature12 into its final position.

FIGS. 29(a) to29(d) illustrate another vascular filter system according to the invention, which is similar to the vascular filter system ofFIGS. 26 to 29, and similar elements inFIGS. 29(a) to29(d) are assigned the same reference numerals.

In this case eachfilter element6 comprises afinger121 protruding radially inwardly.

In the retaining state theclamp tube120 extends around thefingers121 of thefilter elements6 of thefilter1 to retain thefilter1 in the closed state (FIG. 29(c)) beyond elapse of the predetermined period of time. In particular, in the retaining state theclamp tube120 engages with thefingers121 of thefilter elements6 to clamp thefilter1 in the closed state. In the retaining state theclamp tube120 is located in the region of theapex7 of thefilter1 at the centre of thefilter1. Theclamp tube120 is located radially inwardly of thefilter elements6 of the filter1 (FIG. 29(c)). Thefiltration arms6 extend along the outer surface of theinternal restraint120.

Because of the presence of theclamp tube120, thefilter elements6 are no longer free to move from the closed state to the open state upon elapse of the predetermined period of time. Upon biodegrading/bioabsorbing of theholder122, thefilter elements6 of thefilter1 are retained in the closed state by the clamp tube120 (FIG. 29(d)). In this manner the period of time in which thefilter1 captures thrombus is extended either temporarily or permanently.

As illustrated inFIG. 29(b), thelips12 are deformable to facilitate location of theclamp tube120 around thefingers121 of thefilter elements6 of thefilter1.

Referring toFIGS. 29(e) to29(g) there is illustrated another vascular filter system according to the invention, which is similar to the vascular filter system ofFIGS. 29(a) to29(d), and similar elements inFIGS. 29(e) to29(g) are assigned the same reference numerals.

In this case thelips12 are deformable to facilitate location of theclamp tube130 around thefingers121 of thefilter elements6 of thefilter1, and to facilitate selective removal of theclamp tube130 from thefingers121.

Theclamp tube130 comprises anengagable protrusion131 around which thegrasping wire16 may be looped to assist removal of theclamp tube130 from thefingers121.

To remove theclamp tube130 from thefingers121, the graspingwire16 is looped around the protrusion131 (FIG. 29(f)). The graspingwire16 is moved proximally relative to thefilter1 to draw theclamp tube130 proximally causing deformation of the lips12 (FIG. 29(g)), and removal of theclamp tube130 from thefingers121.

Theproximal hook131 is integral with thesecondary restraint130 and facilitates removal of the permanent/bioresorbablesecondary restraint130 when the need for filtration ceases.

InFIGS. 29(h) to29(k) there is illustrated another vascular filter system according to the invention, which is similar to the vascular filter system ofFIGS. 26 to 29, and similar elements inFIGS. 29(h) to29(k) are assigned the same reference numerals.

In this case thefilter1 comprises a threadeddocking member141 at the distal end of thefilter1. Theclamp tube140 is also threaded. Thedocking member141 is engagable with theclamp tube140 by means of the threaded formations to releasably couple theclamp tube140 in position around the distal ends of thefilter elements6 of the filter1 (FIG. 29(j)). The threaded nature of thedocking member141 and theclamp tube140 facilitates selective removal of theclamp tube140 from the distal ends of thefilter elements6 of thefilter1.

In this thread arrangement thenut140 is employed to extend the period of protection. Thenut140 may be in place upon initial intervention or attached at the time of extension.

Theapex arms6 are retained for the initial period of protection by the bioresorbable coupling means. Theapex arms6 are passed through slots in thebiostable tube141 with an outer thread. One of the slots is closed. Theapex arm6 extending through the closed slot is formed into a lip to hold the threadedtube141 in place. Upon elapse of the predetermined protection period, the bioresorbable coupling means breaks and the capture andapex arms6 revert to their radially biased state. Thebiostable tube141 is retained on theapex arm6 with the lip and becomes endotheliased at the vessel wall. Alternatively if the need for protection persists, the bioresorbable orbiostable nut140 may be threaded over thebiostable tube141 to extend the period of protection. If abiostable nut140 is used, it is possible to remove thenut140 by means of a retrieval system.

Thenut140 may be delivered to thedevice1 by means of thecatheter system11. Thecatheter11 encompasses a funnel, the centeringnose15, thesnare16, and theouter sheath14 with a socket to assist in threading thenut140 over the threadedtube141.

FIGS. 29(l) and29(m) illustrate another vascular filter system according to the invention, which is similar to the vascular filter system ofFIGS. 29(h) to29(k), and similar elements inFIGS. 29(l) and29(m) are assigned the same reference numerals.

In this case theclamp tube140 is movable proximally from a non-retaining position (FIG. 29(l)) to a retaining position (FIG. 29(m)) by rotating theclamp tube140 relative to thedocking member141.

In the non-retaining position the clamp tube ornut140 is mounted to thedocking member141 distally of thedistal end150 of each of thefilter elements6 of thefilter1. In the non-retaining position thefilter1 is not retained in the closed state by theclamp tube140.

In the retaining position theclamp tube140 is mounted to thedocking member141 proximally of thedistal end150 of each of thefilter elements6 of thefilter1. In the retaining position thefilter1 is retained in the closed state by theclamp tube140. Theclamp tube140 extends around thefilter elements6 of thefilter1 to retain thefilter1 in the closed state beyond elapse of the predetermined period of time. In particular, in the retaining position theclamp tube140 engages with thefilter elements6 of thefilter1 to clamp thefilter1 in the closed state.

Thenut140 is preloaded on thebiostable tube141. The threadedtube141 extends distally of theapex arms6 so that thepreloaded nut140 does not retain the apex arms6 (FIG. 29(l)).

Thenut140 may be in the form of a common hexagonal nut or it may be a custom shape with features engagable with a custom designed socket.

Referring toFIGS. 29(n) to29(p) there is illustrated another vascular filter system according to the invention, which is similar to the vascular filter system ofFIGS. 29(h) to29(k), and similar elements inFIGS. 29(n) to29(p) are assigned the same reference numerals.

In this case thedocking member141 is not threaded. Theclamp tube160 is also not threaded. An inwardly protrudinglip161 is provided at the proximal end of theclamp tube160. Thedocking member141 is engagable with theclamp tube160 in a snap-fit manner by means of thelip161 to couple theclamp tube160 in position around the distal ends of thefilter elements6 of the filter1 (FIG. 29(p)).

The snap fit biostable restraint160 is translated over thepre-loaded biostable tube141 with slots for theapex arms6. One of the slots is closed.

In another embodiment, a secondary retaining ring may be deployed from the proximal end into a snap fit arrangement integral with the filter apex. A proximal hook may be used to aid in grasping thefilter1 to locate the secondary restraint.

FIGS. 30 to 37 illustrate a further vascular filter system according to the invention, which is similar to the vascular filter system ofFIGS. 1 to 18, and similar elements inFIGS. 30 to 37 are assigned the same reference numerals.

In this case theretainer50 is provided in the form of a clamp device. Theclamp device50 comprises a plurality ofarms111. Theclamp device50 is movable between an open state (FIG. 36) and a closed retaining state (FIG. 37) by operation of thedelivery catheter51.

As illustrated inFIG. 33, the twelvefilter elements6 are arranged into six pairs. For each pair, the distal tip of onefilter element6 is attached to the distal tip of theother filter element6. In this manner aloop opening100 is formed between each pair offilter elements6.

In the retaining state thearms111 of theclamp device50 extend through theloop openings100 betweenadjacent filter elements6 of thefilter1 to retain thefilter elements6 of thefilter1 in the closed state (FIG. 32) beyond elapse of the predetermined period of time. In particular, in the retaining state theclamp device50 engages with thefilter elements6 of thefilter1 to clamp thefilter1 in the closed state. Theclamp device50 is located in the region of theapex7 of thefilter1 at the centre of thefilter1.

Thedelivery catheter51 is employed to deliver theclamp device50 to thefilter1 after thefilter1 has been deployed in theinferior vena cava2. Thedelivery catheter51 comprises aninner tube52, anouter sheath53, and anexpandable member54 at the distal end of anintermediate tube55 upon which theclamp device50 is mounted.

It will be appreciated that in the retaining state thearms111 of theclamp device50 may alternatively extend through an opening in afilter element6 of thefilter1 to retain thefilter elements6 of thefilter1 in the closed state beyond elapse of the predetermined period of time.

In use, theclamp device50 is mounted on theintermediate tube55 of thedelivery catheter51. Thedelivery catheter51 is advanced through theinferior vena cava2 until theclamp device50 reaches the distal ends of thefilter elements6 of thefilter1, which has previously been deployed in the inferior vena cava2 (FIG. 30). Theouter sheath53 is retracted to uncover the clamp device50 (FIG. 35). Theinner tube52 is moved proximally relative to theintermediate tube55 to expand theexpandable member54 thereby moving theclamp device50 from the closed retaining state to the open state (FIG. 36).

Thedelivery catheter51 is advanced further through theinferior vena cava2 until thearms111 of theclamp device50 extend through theloop openings100 betweenadjacent filter elements6 of the filter1 (FIG. 31). Theinner tube52 is moved distally relative to theintermediate tube55 to contract theexpandable member54 thereby moving theclamp device50 from the open state to the closed retaining configuration (FIG. 37). In the retaining state theclamp device50 engages with thefilter elements6 of thefilter1 to clamp thefilter1 in the closed state beyond elapse of the predetermined period of time (FIG. 32). Upon elapse of the predetermined period of time the holder biodegrades/bioabsorbs. Thefilter elements6 of thefilter1 are retained in the closed state by theholder clamp device50. In this manner the period of time in which thefilter1 captures thrombus is extended either temporarily or permanently.

As illustrated inFIG. 32, theclaw type device50 may be used to restrain thefiltration elements6 from opening. For insertion through theloops100 of thefiltration elements6, theclaw50 is opened through shape memory or mechanical actuation, after which theclaw50 reverts to its closed state. The closed state may be achieved through shape memory properties or mechanical actuation. The proximal end of theclaw50 may encompass a conical, spherical, or parabolic geometry in order to minimise stagnant areas and resistance to blood flow.

Thevena cava filter1 has thedevice50 which can be used to change thefilter1 into a permanent filter if the indications of the patient changed or were incorrectly assessed at the time of implantation. A means of achieving this would be to use thecatheter51 to place a cap, tie or other locking mechanism at theapex7 of thefilter1 to hold theabsorbable filter elements6 in the filter configuration permanently. This could be achieved using thecatheter51 which gains access to the venous system by percutaneous access and delivers thelocking mechanism50 to the filter site.

FIGS. 30 to 32 show the means of doing this using the grabbingtype component50. Theinternal push rod55 is advanced releasing the grabbingcomponent50 which was constrained in thesheath53. The grabbingcomponent50 has arms which engage with thefilter frame6 when advanced. The grabbingcomponent50 is then deformed back to a reduced diameter using the external tube orsheath53.

As illustrated inFIG. 33, at theapex region7 the neighbouringfilter elements6 are close or touching ensuring that the arms of the grabbingcomponent50 engage within thefilter element6 rather than throughneighbouring elements6. Thefiltration elements6 may be arranged to prevent thegrabber50 engaging betweenfiltration elements6.

It may be possible to convert thefilter1 to a permanent filter from either the proximal or distal side facilitating an access route from the femoral or jugular vein. Theclaw50 may be advanced from a proximal or distal approach. Opening of theclaw50 may be achieved mechanically through compression of the tube or ring ofmaterial54. Upon compression, the tube/ring54 expands radially, thus opening theclaw50. Once in position, theclaw50 is closed through release of the compressive force. To achieve the closing mechanism, theclaw50 may be manufactured from a shape memory or spring material.

The number ofarms111 of the clamp device may be varied as appropriate. For example theclamp device110 ofFIG. 37(a) comprises sevenarms111, and is suitable for use with the six pairs offilter elements6. By includingmore arms111 on theclamp device110 thanloop openings100 between thefilter elements6, this results in a degree of redundancy to ensure that thearms111 of theclamp device110 will extend through theloop openings100 to safely retain thefilter elements6 of thefilter1 in the closed state. Only oneclaw111 needs to extend through a pair of joinedfilter elements6. The sevenprong claw110 will always catch with thefilter1 comprising six joined filter element pairs.

Referring toFIGS. 38 to 42 there is illustrated another vascular filter system according to the invention, which is similar to the vascular filter system ofFIGS. 1 to 18, and similar elements inFIGS. 38 to 42 are assigned the same reference numerals.

In this case aretainer60 is provided in the form of a tie element to tie thefilter elements6 of thefilter1 in the closed state beyond elapse of the predetermined period of time. Thetie element60 is of a flexible material that may be knotted. Thetie element60 is movable between an open delivery configuration (FIG. 39) and a closed retaining configuration (FIG. 41).

Thedelivery catheter61 is employed to deliver thetie element60 to thefilter1 after thefilter1 has been deployed in theinferior vena cava2.

Thelasso60 may be used to extend protection permanently/temporarily. Thelasso60 is advanced within thedeployment catheter61 from a proximal or distal approach. When it has engaged with the ends of thefiltration elements6, it is tightened and detached from thecatheter61.

Thefilter1 may be changed into a permanent filter if the indications of the patient changed or were incorrectly assessed at the time of implant. A means of achieving this would be to use thecatheter61 to place a cap, tie or other locking mechanism at theapex7 of thefilter1 to hold theabsorbable filter elements6 in the closed, capturing, state permanently. This could be achieved using thecatheter61 which gains access to the venous system by percutaneous access and delivers thelocking mechanism60 to thefilter1.

To retain thetie60 or cap at theapex region7, theelements6 are extended past theapex point7.

Theretainer60 may be provided in the form of a helical coil or spring deployed from thecatheter61 to retrain thefilter elements6 from opening. Shape memory or spring materials may be used.

A potential means of doing this is by using thelasso type feature60 which engages with theapex7 of thefilter1 and is tightened to fix thefilter1 before theloop60 is detached from thecatheter61. Theloop60 could be designed with ratchet type features so it locks in place when it is being tightened (FIG. 43). Thetaut loop60 may be secured via a knot (FIG. 42) or ratchet lasso/loop system (FIG. 43). The taut secure loop/lasso60 may be detached by a screw (FIG. 44(a)), by a mechanical cut (FIG. 44(b)), by shear load (FIG. 44(c)), or by a tensile load system. The loop/noose60 could be detached using a screw attachment (FIG. 44(a)). Also a cutting mechanism may be designed into thecatheter61 to cut the noose (FIG. 44(d)). It is also envisaged to have a reduced cross section beside the detachment point and provide an electric current to break the wire.

The loop of material for thelasso60 can be made such that it would be bioabsorbable/biodegradable and thus extend the duration that thefilter1 will remain in the closed configuration. Alternatively the material may be a biostable material such that thefilter1 will not convert at any time.

Thelip12 may be formed integrally in thefilter element6, as illustrated inFIGS. 45 to 49. A method of manufacturing thefilter1 is shown inFIGS. 45 to 49. Firstly a notch is machined in thestrut6 at the distal end of thefilter1 as shown inFIG. 46. The tip of thefilter arm6 is then heat-set in a shape similar to that shown inFIG. 47.FIG. 46 illustrates thestrut6 with the notch created, andFIG. 47 illustrates thestrut6 heat-set into position.

Thefilter element arms6 may then be constrained together in the filtering closed state for the original period until elapse of the predetermined period of time using theholder65 which may be provided in a variety of possible means, for example a piece of biodegradable suture tied at the ends. Theholder65 temporarily holds thefilter elements6 in the closed state until elapse of the predetermined period of time.

The notches on thefilter element arms6 provide a suitable anchoring location for the biostable orbiodegradable retainer loop60 to be deployed over thebiodegradable holder65 around thetips12 and tightened down to hold thefilter elements6 temporarily or permanently in the filtering configuration beyond elapse of the predetermined period of time (FIG. 48). Theretainer60 extends the period of filtration.

FIG. 45 illustrates thedegradable holder65 in place.FIG. 48 illustrates thesecondary retainer60 deployed over theprimary holder65.FIG. 49 illustrates thesecondary retainer60 after theprimary holder65 has bio-degraded/bio-absorbed.

It will be appreciated that a variety of types of tie element may be used to tie thefilter elements6 of thefilter1 in the closed state beyond elapse of the predetermined period of time.

It will be appreciated that a variety of types of retainer may be used to constrain thefilter elements6 of thefilter1 in the closed state beyond elapse of the predetermined period of time, for example a coil, loop, ring or cap.

InFIGS. 50 to 55 there is illustrated another vascular filter system according to the invention, which is similar to the vascular filter system ofFIGS. 38 to 42, and similar elements inFIGS. 50 to 55 are assigned the same reference numerals.

In this case thetie element70 is woven around and through thefilter elements6 to tie thefilter elements6 of thefilter1 in the closed state beyond elapse of the predetermined period of time.

Thedelivery catheter71 is employed to deliver thetie element70 to thefilter1. Thedelivery catheter71 comprises aninflatable balloon72 to assist in centering thedelivery catheter71 in the blood vessel2 (FIG. 51).

As illustrated inFIG. 51, thecoil deployment catheter71 is advanced to the site of theimplant1 via a proximal approach until the distal tip is centred in thevessel2 by the conical shape of theimplant filtration elements6. Theinflatable balloon72 may be incorporated to aid centring of thecatheter71. Thecatheter71 may also be advanced from a distal approach.

Thecoil70 is preprogrammed through shape memory to change direction/orientation as a length of thecoil70 is deployed (FIG. 52). As thecoil70 changes direction, it winds itself in between thefiltration elements6 until a binding matrix is formed at theapex7 of the filter portion. Thecoil matrix70 restrains thefiltration elements6 from opening when the original biodegradable restraint finalises its degradation process. Once thecoil70 is deployed, thedelivery catheter71 is removed.

FIG. 56 illustrates a further vascular filter system according to the invention, which is similar to the vascular filter system ofFIGS. 1 to 18, and similar elements inFIG. 56 are assigned the same reference numerals.

In this case theretainer80 is provided in the form of a support ring.

Thesupport ring80 extends around the proximal ends of thefilter elements6 of thefilter1 to retain thefilter1 in the closed state beyond elapse of the predetermined period of time. In particular, thesupport ring80 engages with thefilter elements6 of thefilter1 to support thefilter1 in the closed state. Thesupport ring80 is located in the region of the end of thefilter elements6 opposite to theapex7 of thefilter1 at the side of thefilter1.

Thesupport ring80 may be inflatable via hydrogel or saline, or may be a solid ring. Thesupport ring80 may be deployed from a catheter within thefilter1 to restrain thefiltration elements6 at the wall of thevessel2, between the wall of thevessel2, or at the central axis of thevessel2.

The location of the retainer relative to thefilter1 may be varied, as illustrated inFIGS. 57 to 59. The retainer may engage with thefilter elements6 of thefilter1 and/or with the support struts5 of thefilter1 to support thefilter1 in the closed state. The retainer may extend along part or substantially all of thefilter elements6. The retainer may be located at any suitable point along thefilter elements6.

The restraining device may encompass supports extending distal and/or proximal of the restraint (FIG. 59). This support may be in the form of a tubular mesh.

Referring toFIGS. 60 to 62 afilter150 hasfilter elements151 which are curved inwardly and proximally at their distal ends. Thefilter elements151 are held in the closed state by abiodegradable holder152. Also, thefilter elements151 include retainer disc-shapedmagnetic parts153 located at the bends at the distal ends. The retainer also comprises a washer-shapedsecond part155 which is delivered by acatheter160 so that it engages the firstmagnetic parts153. The complete retainer thereby holds the filter elements in the closed state (FIG. 62). In more detail themagnetic inserts153 may be positioned by heating the filter elements and then cooling to secure themagnetic inserts153. Alternatively, they could be bonded or crimped in place. The retainersecond part155 may be deployed without need for a snare or funnel guiding system, but these may be provided additionally if desired. During deployment of the retainer second part, the magnetic attraction between thepart155 and the filter elements is greater than that between thepart155 and the catheter. Theretainer part155 may be coupled to the catheter by an interference fit in place of or in addition to the magnetic attraction.

Referring toFIGS. 63 and 64 afilter170 hasfilter elements171 held for a predetermined period of time by abiodegradable holder173. Thefilter elements171 have bends at their distal ends, the bends being faced inwardly and theends174 of theelements171 extending radially outwardly. Eachfilter element171 has a retainermagnetic insert172. To extend the protection period, the filter element hook ends are grasped with asnare180 which is tightened to bring the apex and the catheter into close contact. The cathetercentral shaft181 andsheath183 are held stationary and apusher182 advances amagnetic collar185 over thefilter element magnets172. The magnetic attraction forces prevent thecollar185 from slipping. Thecentral shaft181 may have a reception space for the filter element hook ends. Thecollar185 is held in position in the delivery system by an interference fit or by a magnetic insert on thecentral shaft181. Alternatively, thecollar185 may be attached to the pusher by magnetism. Of course, in order for the pusher to release thecollar185, the magnetic attraction force between the collar and the pusher should be less than that between the filter elements and the collar. The filter element ends may extend proximally in order for the extension step to be performed from a femoral approach.

Referring toFIGS. 65 and 66 afilter200 comprisesfilter elements201 held by abiodegradable holder202. Thefilter elements201 terminate at the distal end with atip203 somewhat like an arrow head. For retaining the closed state beyond the predetermined period of time an expandedfunnel210 is moved by a catheter having afunnel sheath211 and acentral shaft212. The catheter delivers aretainer213 which is cup-shaped, with an internal rim. For delivery, after the delivery system is advanced to the site, the self-expandinglocating funnel210 is expanded by retracting thesheath211. The funnel fits neatly over the, similarly shaped, filter. The assembly is advanced further and a slight force is applied for theretainer213 to snap over thetips203. This force is low to avoid damage to the vessel wall. The assembly is retracted and the sheath is advanced to collapse the funnel before removing it from the patient. An offset lumen may be provided in the catheter to allow passage of a guide wire and/or snare. Theretainer213 may have a hook on the distal end to allow removal at a later stage. The retainer may have a reception space on the distal end (like a miniature version of that on the proximal side) so that it could be releasably attached to a snap feature on the pusher, the locking force between the filter elements and the retainer would need to be greater than that between the retainer and the pusher in order to disengage from the pusher.

In another embodiment of the invention the retainer is selectively movable by application of an energy stimulus from a non-retaining configuration in which thefilter1 is not retained in the closed state, to a retaining configuration in which thefilter1 is retained in the closed state.

For example, the retainer may comprise a cure adhesive. The retainer may be selectively movable by application of ultraviolet light from the non-retaining configuration in which thefilter1 is not retained in the closed state, to the retaining configuration in which thefilter1 is retained in the closed state.

For example, the retainer may comprise a biostable polymer. The retainer may be selectively movable by application of heat or an electric current to cure the polymer from the non-retaining state in which thefilter1 is not retained in the closed state, to the retaining state in which thefilter1 is retained in the closed state.

For example the retainer may comprise a biostable polymer. The retainer may be selectively movable by application of heat or an electric current to transform a non restraining polymer arrangement in which thefilter1 is not retained in the closed state, into a restraining polymer arrangement through melt flow in which thefilter1 is retained in the closed state.

For example, the retainer may comprise a two-part epoxy system. The retainer may be selectively movable by addition of the second part from the non-retaining state in which thefilter1 is not retained in the closed state, to the retaining state in which thefilter1 is retained in the closed state.

For example, the retainer may be selectively movable by application of a magnetic field from the non-retaining configuration in which thefilter1 is not retained in the closed state, to the retaining configuration in which thefilter1 is retained in the closed state.

It is appreciated that the secondary retainers disclosed above can be manufactured using a biodegradable or a biostable material to extend the protection period temporarily or permanently. If a biodegradable secondary holder is selected, it is possible to perform an additional intervention to extend the protection period further.

It will be appreciated that more than one retainer may be employed to extend the period of time in which thefilter1 captures thrombus. For example in the case where a first retainer is biodegradable and/or bioabsorbable, a second retainer may be employed to further extend the period of time in which thefilter1 captures thrombus beyond biodegrading/bioabsorbing of the first retainer. Any of the retainers may be of any suitable form as described herein. The first retainer may be of the same type or of a different type of retainer as the second retainer.

The retaining members used to extend the protection period may also be used with multistage filters. Consider a double convertible cone filter with a coarse proximal filter and a fine distal filter that separates clot particles by size where smaller particles travel through the coarse proximal filter and are trapped by the fine distal filter. The fine distal filter is intended to capture smaller particles that would normally be clinically insignificant but would present a risk to a patient with poor pulmonary reserve. After the patient has recovered to the extent that pulmonary reserve is improved but pulmonary embolism is still a risk, it would be desirable to extend the protection period only for the coarse proximal filter. The coarse filter is less likely to become blocked with smaller clinically insignificant particles. Having the coarse filter proximal

It is appreciated that the filter embodiments discussed above can be used for general embolic protection in any blood vessel.

It will also be appreciated that the invention is not limited to use with vena cava filters. The invention may also be employed to replace one or more bioresorbable materials in other vascular devices, such as a stent, with one or more biostable components.

The invention is not limited to the embodiments hereinbefore described, with reference to the accompanying drawings, which may be varied in construction and detail.