AU2005200491B2 - An embolic protection device - Google Patents

Description

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AUSTRALIA

Patents Act COMPLETE SPECIFICATION

(ORIGINAL)

Class Int. Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority Related Art: Name of Applicant: Salviac Limited Actual Inventor(s): Paul Gilson, Eamon Brady, David Vale, Padraig Maher, Charles Taylor Address for Service and Correspondence: PHILLIPS ORMONDE FITZPATRICK Patent and Trade Mark Attorneys 367 Collins Street Melbourne 3000 AUSTRALIA Invention Title: AN EMBOLIC PROTECTION DEVICE Our Ref: 738195 POF Code: 323361/452074 The following statement is a full description of this invention, including the best method of performing it known to applicant(s): -1- 2 It is known to permanently implant a filter in human vasculature to catch embolic material. It is also known to use a removable filter for this purpose.

Such removable filters typically comprise umbrella type filters comprising a a, filter membrane supported on a collapsible frame on a guidewire for movement C- 5 of the filter membrane between a collapsed position against the guidewire and a laterally extending position occluding a vessel. Examples of such filters are shown in US 4723549, US 5053008, US 5108419 and WO 98/33443. Various deployment and/or collapsing arrangements are provided for the umbrella Sfilter. However, as the filter collapses, the captured embolic material tends to be squeezed outwardly towards an open end of the filter and pieces of embolic material may escape from the filter with potentially catastrophic results. More usually, the filter umbrella is collapsed against the guidewire before removal through a catheter or the like. Again, as the filter membrane is collapsed, it will tend to squeeze out the embolic material. Further, the umbrella filter is generally fixed to the guidewire and any inadvertent movement of the guidewire during an interventional procedure can dislodge the filter.

The above discussion of documents, acts, materials, devices, articles and the like is included in this specification solely for the purpose of providing a context for the present invention. It is not suggested or represented that any or all of these matters formed part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed in Australia before the priority date of each claim of this Application.

Throughout the description and claims of the specification the word "comprise" and variations of the word, such as "comprising" and "comprises", is not intended to exclude other additives, components, integers or steps.

Statements of Invention In one aspect the present invention provides an embolic protection device comprising: a collapsible filter element mounted on a filter carrier to facilitate delivery of the filter element through a vascular system of a patient, Wvssn\DanierSpeaRDMC 2005 200491 Spea Amendmets l4dec07.doc a tubular element extending substantially the entire length of the filter C element, the filter element being rotatable relative to the filter carrier, the filter element being movable between a collapsed stored position against the tubular element for movement through the vascular system, and an C 5 expanded position for occluding a blood vessel such that blood passing through the blood vessel is delivered through the filter element, the filter element comprises a collapsible filter body having an inlet end and an outlet end, Sthe inlet end of the filter body having one or more inlet openings sized to allow blood and embolic material enter the filter body, 0the outlet end of the filter body having a plurality of outlet openings sized to allow through passage of blood but to retain undesired embolic material within the filter body, and a tubular filter retrieval device having an open distal end for reception of the filter element.

Advantageously, the inlet openings in the filter are closed before the filter is collapsed ensuring retention of an embolic material within the filter element.

In a particularly preferred embodiment of the invention, said distal end of the retrieval device is engagable with a proximal inlet end of the filter body to close the inlet openings. Said distal end of the retrieval device may be slidable over the filter body from the inlet end to the outlet end to progressively collapse the filter body against the tubular element and receive the filter body within the retrieval device.

Conveniently, the retrieval device which may be a catheter or pod or the like which engages and collapses the filter element firstly closing the inlet openings to prevent any escape of embolic material and then collapsing the remainder of the filter, being slide from the proximal end over the filter to the distal end of the filter.

In a particularly preferred embodiment, the collapsible filter element is slidably mounted on the filter carrier between the pair of spaced-apart stops on the W Xshv n\ruOaeASpecDMC 2005 200491 Sped Amendments 14dec07 dc L filter carrier for axial movement of the filter element along the filter carrier Sbetween the stops.

Advantageously, the filter carrier which may for example be a guidewire can be moved independently of the filter element and thus accidental movement of the guidewire is accommodated without unintentionally moving the filter, for example, during exchange of medical devices.

SIn a preferred embodiment, a sleeve is slidably mounted on the filter carrier between the stops, the length of the sleeve being less than the distance between the stops, the filter element being mounted on the sleeve.

In a particular preferred embodiment, the filter element comprises:a collapsible filter net mounted on the filter carrier, the filter net being movable between a collapsed stored position against the filter carrier and an expanded position extending outwardly of the filter carrier for deployment across a blood vessel.

Preferably, the tubular filter retrieval device comprises a catheter slidable along the filter carrier, an open distal end of the catheter forming a housing for reception of the filter element.

In another embodiment, a proximal inlet end of the filter body is fixed to the filter carrier and a distal end of the filter body is slidably mounted on the filter carrier, although this arrangement may be reversed.

In a further embodiment, the distal end of the filter body is attached to a collar which is slidable along the filter carrier.

In a preferred embodiment, a filter support frame is mounted on the filter carrier, the support frame being movable between a collapsed position along the filter carrier and an extended outwardly projecting position to support the filter body in the expanded position.

Wshamn00alefSpea'MC 2005 200491 Sped Amendmers I4ede7Wdoc Carrier and at the other end the wires being mounted on a collar which is c slidable along the filter carrier, a porous filter mesh being mounted on the wire frame. An actuating sleeve is slidable over the filter carrier to push the collar a) towards the fixed end of the filter element, and a collapsing device is engagable with the collar to pull back the collar away from the fixed end of the filter element to collapse the wire frame against the filter carrier for retrieval of the filter element.

0 In a still further emelboidment of the invention, there is provided a filter retrieval system for use with the device comprising a longitudinal catheter with a rapidly Sdeformable or elastic tip to assist the pull back of the filter into the tip.

In another embodiment of the invention, there is provided a system incorporating a filter, a delivery catheter and a retrieval catheter for temporary filtration of the vascular system during an interventional procedure.

Herein there is also disclosed an embolic protection device comprising: a collapsible filter element mounted on a filter carrier for delivery through a vascular system of a patient, the filter element being movable between a collapsed stored position against the filter carrier for movement through the vascular system, and an expended position for occluding a blood vessel such that blood passing through the blood vessel is delivered through the filter element, a pair of spaced-apart stops on the filter carrier, the collapsible filter element being slidably mounted on the filter carrier for axial movement along the filter carrier between the stops, and means for collapsing the filter element on the filter carrier.

Brief Description of Drawings The invention will be more clearly understood from the following description thereof given by way of example with reference to the accompanying drawings in which:- Fig. 1 is a side view of an embolic protection device according to the invention, WAshamn\DardeftSpedefMC 2005 200491 Sped Amendments 14dec07 hoc -6-

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in use; SFig. 2 is a side view of the device of Fig. 1 in a pre-loaded position for 0 insertion; 0 N Fig. 3A is a side view illustrating one method of fixing the device to catheter; Fig. 3B is a side view of an embolic protection device incorporating the fixing of Fig. 3A; Fig. 4 is a side view illustrating another method of fixing; Fig. 5 is an end view of a split collar used in the fixing of Fig. 4; Fig. 6 is a side view illustrating a further method of fixing; Fig. 7 is an end view of a jubilee clip used in the fixing of Fig.6; Fig. 8 is a side view of one filter element used in the device of the invention; Fig. 9 is a side view of another filter element; Fig. 10 is a side view of the filter element of Fig. 8 being removed; Fig. 11 is an isometric view of another fiter element in an in-use placed configuration; Fig. 12 is a side view of the filter element of Fig. 11 in a retracted position for insertion and withdrawal; Figs. 13 to 15 are side views of another filter element in different positions; Figs. 16 and 17 are side views of part of a further filter element with a snap fit retrieval arrangement; DocumentS -7-

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Fig. 18 is a perspective, partially cross-sectional view of another embolic protection device shown mounted in a vessel; Figs. 19a to 19c are perspective views illustrating the formation of a collapsible filter support for use in the device of Fig. 18; NC Figs. 20 to 22 are perspective views of other filter elements; Fig. 23 is an elevational view of another filter element; Fig. 24 is a sectional view taken abng the line XXIV-XXIV of Fig. 23; Fig. 25 is a sectional view taken along the line XXV-XXV of Fig. 23; Fig. 26 is an enlarged detail view of portion of the filter; Fig. 27 is an expanded view of the filter element of Fig. 23; Fig. 28 is a side view illustrating one method in which the substrate tubing that the filter element is attached to can run over the primary crossing guidewire; Fig. 29 is a side view illustrating the position in which the "olive" component will sit in order to provide a smooth transition between the primary crossing guidewire and the loading pod; Fig. 30 is a perspective view of the filter element in its most distal position; Fig. 31 is a perspective view of the fitter element in its most proximal position; Fig. 32 is a perspective view of the filter element when the distal end of the filter is not bonded to the substrate tubing; Fig. 33 is a side view of a concertina shaped filter; A being when the filter is -8-

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deployed and B when the filter is in its loaded shape; SFig. 34 is a perspective view of the floating distal tip design with a spring element incorporated distal to the floating tip; SFig. 35 is a side view of another floating distal tip design with a spring Sincorporated into the distal tip; Fig. 36 is a side view of the floating distal tip design with the shape memory alloy extending from the proximal end to the distal end; Fig. 37 is a perspective view of the mesh design incorporating a floating distal tip; Fig. 38 illustrates perspective views of filter geometries; Fig. 39 shows a fibrous mesh filter design with fibres woven at the distal end and converging into a number of bundles at the proximal end; Fig. 40 is partially sectioned elevational view an embolic protection device according to the invention; Fig. 41 is a schematic sectional elevational view of the embolic protection device of Fig. 40; and Fig. 42 is a detail sectional view of portion of the device of Fig. Detailed Description Referring to the drawings there are illustrated various embolic protection devices according to the invention. The devices, in general, comprise a filter element for temporary placing in a desired position during a surgical or interventional procedure, typically using a guidewire and catheter. The filter element provides a pathway for blood and has means for capturing and retaining undesired embolic material released -9during the surgical procedure. The filter element containing the retained embolic material is removed when the interventional procedure is completed. In this way the Spatient is protected against the risk of stroke or other complications caused by the release of undesired embolic material during the procedure.

In one embodiment of the device it will be used in an over the wire transcatheter Sconfiguration. The clinician will cross the lesion with a steerable guidewire. The cerebral protection device will then be threaded over the guidewire and will be placed distal to the site of the lesion being treated. By means of actuation, or other means, the filter is deployed into the vessel and will capture emboli that are generated or dislodged during balloon inflation and stent placement. The device consists of a filter attached to a shaft that can run over the primary crossing guidewire.

Referring initially to Figs. 1 and 2 in this case the filter element consists of a compressible porous structure polymeric foam filter element 1 overmoulded onto or joined to a polymeric or metallic tube or spring or other hollow support element 2. The foam filter element 1 is compressed into a housing or pod 3 at a distal end of a catheter 6 to advance it to the required location. Once in situ the housing 3 is withdrawn or the filter element 1 is advanced. This action allows the compressed fitter element 1 to expand to the required size and occlude a blood vessel 4 except for the path or paths provided through the filter element 1. The filter element 1 is designed to provide a pathway or multiple pathways through for blood cells and other blood constituents but to capture emboliof a size greater than the filter pore size. Blood flow rate is maintained by forming the filter element such that a local pressure drop across the filter is minimised. The filter element 1 has a proximal inlet end 7 and a distal outlet end 8. The inlet end 7 has a plurality of inlet openings sized to allow blood and embolic material enter the filter element. The outlet end 8 has a plurality of outlet openings sized to allow through passage of blood but to retain undesired embolic material within the body of the filter element 1.

The filter element 1 in this case is of a porous structure or polymeric foam which has a open cell structure with a typical density less than 400 kg per cubic meter. Preferably the density will be less than 100 kg per cubic meter and ideally will be less than 50 kg per cubic meter. The fitter properties may be achieved through appropriately sizing the pores of the foam body or additionally by removing material to create appropriately sized pathways for blood to flow through and means of capturing larger sized particles. A number of configurations for this will be described that can tailor both the sizing and flow rate characteristics of the filter element 1 either, independently or simultaneously. The actuation and deployment of the filter element 1 are achieved by cproviding relative motion between the filter element 1 and the covering housing 3.

It is not desirable that the catheter moves relative to the support element 2 during manipulation. Motion may be prevented by fixing the inner support element 2 to the catheter 6 in a number of different ways. In the embodiment described this is achieved by way of having a catheter 6 covering the support element 2 and filter element 1 to which it is fixed. As illustrated in Figs. 3A and 3B the fixing may be achieved by means of a shrink wrap tube 5 that is shrunk to capture both the covering catheter 6 and the inner support element 2. Once the filter element 1 is in the desired position, the shrink-wrap joint is.broken using the peel-away tab 7 to allow the outer catheter 6 to be removed proximally and leave tle support element 2 and filter element 1 in place.

A number of other workable arrangements could be used to join the support element 2 and catheter 6. A split collar arrangement 10 (Figs. 4 5) could be used that was removable by means of unlocking a screw or a number of screws or an arrangement such as a jubilee clip 11 (Figs. 6 7) which could be loosened t6 free the bond between the components.

Another method that could be used to temporarily fix the inner support element 2 to the outer sheath or catheter 6 is a Hemostasis High'Pressure Touhy Borst Y adapter.

This commercially available adapter is needed to enable the physician to flush the sheath before being inserted into the artery. The outer sheath or catheter may be permanently attached to this adapter. The inner tubular support element 2 runs through the Touhy Borst section of the adapter and thus through the centre of the sheath. Tightening the Touhy Borst section releases this grip, thus allowing the inner tubular support element 2 and the outer sheath to move relative to each other once again.

-11 The design of the filter element 1 is shown in a typical embodiment in Fig. 8, where a foam substrate filter body has material removed to create a series of channels or pathways 20 for the blood to flow through but which would cause a restriction for Sembolic material to prevent it going through the filter. The pathways 20 may be machined using a variety of methods such as laser cutting with excimer, YAG, C02, or other laser type, freezing and machining or lost wax machining. A number of arrangements are possible with the sizing reflective of the requirements. In the configuration shown, the inlet holes are preferably 0.5 mm or greater in size to capture large emboli while the outlet holes are less than 300 microns. These can be easily varied as required to filter differing sized particles from a variety of fluid media in a variety of vessel sizes.

The filter media can be bonded to the tubing substrate by way of a variety of available technologies such as mechanical, solvent or adhesive bonding and overmoulding in an arrangement such that the substrate is placed in the mould and the polymer material is then shot into the mould and forms a bond at the interface between the substrate and the polymer element. Additionally, the foam or porous element could be extruded onto or bonded to a substrate.

It will be noted that the filter element 1 has a rounded distal end 21 to facilitate insertion and the proximal end 22 is tapered to facilitate withdrawal. Alternatively, as illustrated in Fig. 9 the distal end 23 may be tapered.

Referring particularly to Fig. 10 at the end of the interventional procedure, the device can be withdrawn by means of advancing a large bore catheter 25 to the proximal end 22 of the filter 1 and pulling the filter 1 into the catheter 25. The filter 1 will compress and seal the proximal filter inlet openings after the initial taper is drawn into the catheter 25 before collapsing the rest of the filter body. Once the filter 1 has been withdrawn fully into the catheter 25 it can then be readily removed from the patient.

The filter 1 will contain the captured emboli.

In another embodiment of the invention as illustrated in Figs. 11 to 15, an arrangement of spokes 30 covered with a membrane or porous fabric or mesh 31 can be folded down into a delivery sheath or pod for subsequent deployment in the target Documents -12-

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vessel. The design consists of a substrate shaft 33 onto which are radially or circumferentially bonded a series of pre-shaped wires 30. The wires 30 are joined on _the proximal end into a movable collar or tube 32 mounted on the substrate shaft 33 and at the distal end into a fixed tube 34. The tube 32 can move proximally and distally to the extent that it will open and close the assembly in a manner similar to an umbrella and thereby occlude the vessel. The spokes 30 may be fabricated in a Srange of metallic, polymeric and composite materials. The frame is covered with a Sporous material 31, whose pore size is selected to allow the media through, effectively creating a screen filter. The covering fabric 31 could be bonded to the frame 30 by means of casting a material such as a polyurethane or PET onto the pre-formed shape. The film may then be lazed or made porous by other means such as mechanical or heat punching or by chemical etching. Additionally, incorporating a soluble particle in the polymer matrix, subsequent removal of the particle would render the polymer porous. Control of porosity is achieved by tailoring the ratio and distribution of the particulate within the polymer matrix.

When the assembly is configured longitudinally a sheath or pod may be slid over it to cover it. As with the previous embodiment, the loaded catheter is positioned in the required location by threading it over the guidewire. Once the desired location has been reached, the sheath may be moved back and allow the assembly be exposed in the vessel. A sleeve 35 can then be moved forward to open or deploy the assembly.

The relative sizing and choice of materials operates such that the sleeve 35 will not slide on the inner tubing unless an external force is applied to move it. When deployed, the device will remain open and catch whatever embolic material is moving towards the brain. At the end of the procedure, a pre-shaped component advanced over the inner tube will dock with the movable tube 32 and allow it to be slid towards the proximal end of the device with the result that the structure is closed. A larger sheath can then separately be advanced to the site of the filter and the filter may be pulled or manipulated proximally into it. When withdrawn into the sheath or catheter, the device may then be removed either over the guidewire or with it.

Referring to Figs. 16 and 17 there is illustrated another embolic protection device. In this case the filter element has a design based on a shaped thin film component bonded onto the tubing substrate. A wide number of shapes could be made to work -13in the application. An element which through it's preshaped form will open into a framework 40 when the restraining force is removed is attached to a tubing substrate 41. The frame element 40 can be manufactured from a range of metallic or polymeric components such as a shape memory alloy like Nitinol or a shape memory polymer or a shaped stainless steel or metal with similar properties that will recover from deformation sufficiently to cause the film component to open. Otherwise a mechanical movement or actuation can cause the device to open. The shaped film component is attached over the frame 40. The film component can be formed by a number of known commercial technologies. These include blow-moulding, dip casting, solution casting, spin casting and film welding as well as adhesive joining. The object is to produce a formed shape that can be opened in the vessel to a size and shape to occlude it. Filtration is achieved by creating a pattern or series of openings in the proximal and distal ends of the element that allows emboli and blood to enter the device but having a range of smaller openings in the distal end to allow the blood to pass through to the distal vasculature while retaining the emboli.

While being delivered to the required site, the filter element is covered or restrained by a sheath. By withdrawing the sheath or advancing the filter device, the filter is uncovered and opens to occlude the vessel. During the procedure, the filter acts to capture all embolic material that attempts to flow distally. At the end of the procedure, a sheath is advanced to the proximal end of the device and the fitter is pulled proximally into it with the retained emboli captured. In this design configuration, the emboli can easily be removed for analysis afterwards.

The invention above is described as it relates to a device that can be used over a medical guidewire. The opportunity exists to configure the invention in a manner that it could in itself be used as the primary crossing device. All of the fiter designs described above could be mounted onto either the over the wire or the primary crossing device as described hereunder. For a primary crossing device the filter would be bonded to a solid substrate. Some benefits would accrue in that the inner diameter onto which the filter could be wrapped down would be smaller because it would not need to move over another instrument. Fig. 18 iilustrates the differences involved. The filter element 1 is mounted on the substrate shaft 33. A collapsible filter support element 50 is mounted on the substrate shaft 33 at a proximal end of the fitter -14- 1. The support element 50 has a number of foldable arms 51 which collapse against Sthe shaft 33 for deployment and upon release extend outwardly to expand the filter 1 in the vessel.

Referring to Figs. 20 to 22 there is shown alternative constructions of filter element comprising a compressible filter 1 shown in an expanded position with a large inlet opening 60 and smaller outlet openings 61. A collapsible wire support 62 is provided at a proximal end of the filter 1. The wire support 62 is collapsible with the filter 1 within a housing or pod for deployment and upon release expands to support the filter 1 in the vessel 4.

An alternative filter arrangement is shown in Figs. 23 to 27. In this case, the filter comprises a Nitinol mesh which is expandable from a collapsed position shown in Fig.

23 for deployment to an expanded in use position shown in Fig. 27 to provide a filter body 65 with proximal inlet 66 and distal outlets 67.

For a primary crossing device, the distal end of the device will be flexible and atraumatic. This can be achieved by a number of means such as fabricating a spring or polymeric element to be flexible enough to deflect when it comes into contact with the walls of the vessel. The tip section would be mounted distally to the filter element.

An intermediate section of the device will house the filter 1 which would be covered prior to deployment. A sheath could be fully the length of the device or attached by an actuator to a shorter sheath that covers the filter only. The proximal section of the device will provide a platform for the balloon dilatation and stent devices. The provision of a platform may be achieved as shown by removing the proximal covering to expose a wire or spring assembly. Altematively, the whole proximal section could function as the platform. Essentially, to function as the platform for balloon catheter and stent, the devices should be sized with an outside diameter dimension that allows free movement of the catheter systems over it. Typical industry standards for coronary products permit free movement of devices over a .014" or 0.018" diameter while peripheral angioplasty applications use a .035" 00.

Referring to Fig. 28 the tubing substrate 33 onto which the filter element is bonded can move between two stoppers 63 and 64, the stoppers are mounted on the primary crossing guidewire 2. The stoppers can be manufactured from a range of metallic or polymeric components, which will permit movement of the tubing substrate 33 between them. The stoppers may also be in the form of a step in the actual medical 0 guidewire. A large variation in distances between stoppers 63 and 64 could be made to work in this application. The stoppers are sized to prevent movement of the tubing Ssubstrate either over or under them so that they act as a stop position for the tubing substrate in both their proximal and distal locations. The stoppers can be mounted onto the primary crossing guidewire by a number of known commercial technologies; these include soldering, welding, braising, crimping and adhesive bonding. The proximal stopper will be small enough in size to fit into the internal shaft of the delivery catheter. The filter element can move axially and rotationally independently of the guidewire. This allows for good wire movement and control of filter position. The filter position will be maintained during the exchange of catheters. Any commercially known available guidewire can be adapted accordingly and used with this technique.

Fig. 29 refers to an "olive" 65; the olive component can be manufactured from a range of metallic or polymeric components such as polymeric foams, plastics, stainless steel or metal. The olive will allow a smooth transition between the guidewire 2 and the pod 3 into which the filter element is loaded and also allows for easypositioning of the filter element within the pod. The olive can be directly attached to the guidewire or it may also be attached to a tubing substrate 33. The olive can be attached to the guidewire or tubing substrate by a range of known techniques such as adhesive bonding and soldering. The olive will work as required for a range of distances distal to the filter elemenL A wide number of shapes and sizes could be made to work as the olive component.

Fig. 30 refers to the filter element 1 when it is positioned in its most distal position.

The filter element may achieve this position during loading or after deployment. The stopper element 64 prevents the fitter element 1 from moving beyond it in the distal direction.

Fig. 31 illustrates the filter element in its most proximal location the filter element may achieve this position when deploying the device or after deployment. The stopper element 63 prevents the filter element 1 from moving beyond it in the proximal -16direction.

Fig. 32 refers to a floating distal tip in this case a stopper component 66 is placed proximal to the distaJ end of the fitter. The most distal end of the filter being fixed to a O 5 marker band 70 or other suitable substrate. The marker band 70 is not fixed to the substrate tubing 33. This allows the distal end of the filter freedom of movement in the axial direction beyond the stopper component. The stopper component can be made to work using any shape or form so as to prevent movement of the distal end of the filter in the proximal direction beyond the point of fixturing of the stopper component.

The stopper component may be manufactured from metals or polymeric material, it can be joined to the tubing substrate 33 by a number of existing technologies including adhesive bonding and soldering. The stopper component 66 will work when placed in any location between 50 and 70. A floating distal tip on the filter element will facilitate the loading of the filter element into the loading pod as the filter can now extend in the axial direction and therefore be wrapped down over a greater length.

This will reduce the loading force required and also reduce the profile of the loaded filter. The floating distal tip design will facilitate the loading of a large range of filter designs. Fig. 33 refers to a concertina shaped filter with a floating distal tip. This filter geometry adds to the circumferential integrity of the filter and thus prevents the formation of creases along the length of the filler. illustrates the filter as it will be when in position. illustrates how the distal tip will extend in the axial direction when the filter element is loaded into a loading pod. The floating tip design can be used to accommodate the loading of many fitter shape designs. For the filter design shown a longer pod is needed to accommodate the increase in axial length of the filter element when loaded.

Fig. 34 refers to the floating distal tip design with a spring element 67 incorporated into the design. The spring is placed distal to the filter element. As previously illustrated in Fig. 33, the floating distal tip extends in the axial direction when loaded, the spring acts as a safety device when the filter is deployed and ensures the return of the floating distal tip to its primary location. The spring element will be soft enough to allow the distal tip to extend freely in the distal direction during loading but stiff enough -17to push the distal tip back to its primary location after deployment. The spring element can be manufactured from either a polymeric or metal component. The spring element can be mounted onto a substrate 33 and a stopper component used to prevent axial movement of the spring in the distal direction. Other methods of keeping the distal end of the spring element stationary could be used such as bonding, welding, crimping, soldering or crimping the distal end of the spring onto the substrate 33. This technique could also be made to work with the spring being part of the actual guidewire. There are many other configurations by which a return spring element may be incorporated into the filter as shown in Fig. 35 and 36.

In Fig. 35 the spring element 67 is bonded to the substrate 33 at its proximal end and the distal end of the filter element is bonded to the spring shaft. This design allows the distal end of the filter element to extend in the distal direction. The extension length could be determined by either the positioning of a stopper 68 or the stiffness of the spring. When external forces are removed from the filter the spring will return the filter to its primary location. In Fig. 36 a shape memory alloy such as nitinol is used to return the filter to its primary location. The nitinol :support frame 69 is fixed to the substrate 33 at its proximal end 70 and is floating at the distal end 71. The shape memory properties of the nitinol will ensure that the filter element returns to its primary location. This design can facilitate the use of any other commercially available or known shape memory alloys. This design could also be made'tio work using a spring component.

Fig. 37 again incorporates the floating distal tip design. The filter body 65 as previously illustrated in Fig. 27 is mounted onto a substrate 33. At the proximal end the stent is fixed to the substrate. The floating distal tip design allows the filter body to extend in the distal direction. As the filter body 65 extends there is a reduction in its outside diameter and an increase in its overall length. There may or may not be need for a stopper 68 as the filter body 65 will extend up to its own elastic limit which is determined by its size and geometry. The shape memory function of the filter body will cause the distal tip to return to its primary location when external forces are removed from it. The proximal end of the filter body 65 may be fixed to the substrate by a number of known technologies such as bonding, soldering or crimping.

Documems 18- Fig. 38 illustrates a number of different filter designs which could be made to work as embolic protection devices. These filter designs all work to reduce the longitudinal length of creases which may occur should the filter be oversized, therefore acting as crease breakers. Either ends of the filters shown could act as both proximal and distal ends for the filter. The filter body may be tubular or frusto-conical.

Referring to Figs. 40 to 42 there is illustrated an embolic protection device according Sto the invention indicated generally by the reference number 100. The device 100 has a guidewire 101 with a proximal end 102 and a distal end 103. A tubular sleeve 104 is slidably mounted on the guidewire 101. A collapsible filter 105 is mounted on the sleeve 104, the filter 105 being movable between a collapsed stored position against the sleeve 104 and an expanded position as shown in the drawings extended outwardly of the sleeve 104 for deployment in a blood vessel.

The.sleeve 104 is slidable on the guidewire 101 between a pair of spaced-apart end stops, namely an inner stop 106 and an outer stop which in this case is formed by a spring tip 107 at the distal end 103 of the guidewire 101.

The filter 105 comprises a mesh net 110 mounted over a collapsible support frame 111. The mesh net 110 is gathered into the sleeve 104 at each end, the net 110 being rigidly attached to a proximal end 112 of the sleeve 104 and the net 110 being attached to a collar 115 which is slidable along a distal end 114 of the sleeve 104.

Thus the distal end of the net 110 is longitudinally slidable along the sleeve 104. The support frame 111 is also fixed at the proximal end 112 of the sleeve 104. A distal end 116 of the support frame 111 is not attached to the sleeve 104 and is thus also free to move longitudinally along the sleeve 104 to facilitate collapsing the support frame 111 against the sleeve 104. The support frame 111 is such that it is naturally expanded as shown in the drawings and can be collapsed inwardly against the sleeve 104 for loading in a catheter 118 or the like.

The filter 105 has large proximal inlet openings 117 and small distal outlet openings 119. The proximal inlet openings 117 allow blood and embolic material to enter the filter body, however, the distal outlet openings 119 allow through passage of blood but retain undesired embolic material within the filter body.

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SAn olive guide 120 is mounted at a distal end of the sleeve 104 and has a cylindrical central portion 121 with tapered ends 122,123. The distal end 122 may be an arrowhead configuration for smooth transition between the catheter and olive surfaces. The support frame 111 is shaped to provide a circumferential groove 125 in the filter net 110. If the fitter is too large for a vessel, the net may crease and this groove 125 ensures any crease does not propagate along the filter.

SEnlarged openings are provided at a proximal end of the filter net 110 to allow ingress of blood and embolic material into an interior of the net 110.

In use, the filter 105 is mounted in a collapsed state within a distal end of the catheter 118 and delivered to a deployment site. When the filter is correctly positioned the catheter 118 is retracted allowing the support frame 111 to expand inflating the net 110 across the vessel in which the fitter is mounted. Blood and emboli can enter the enlarged openings at a proximal end of the net 110. The blood will pass through the net wall, however, the openings or pores in the net are sized so as to retain the embolic material. After use the catheter is delivered along the guidewire 101 and slid over the filter 105 engaging the proximal inlet end 112 first to close the openings and then gradually collapsing the net against the sleeve 104 as the catheter 118 advances over the filter 105. Once the filter 105 is fully loaded in the catheter 118, it can then be withdrawn.

It will be noted that a proximal end of the filter is fixed and a distal end of the filter is longitudinally movable along the sleeve to facilitate collapsing of the filter net.

Further, the catheter engages the proximal end of the filter net first thus closing the fifter net inlet and preventing escape of embolic material from the filter net as the filter net is being collapsed.

Conveniently the tip of the catheter which forms a housing or pod for reception of the filter is of an elastic material which can radially expand to accommodate the filter with the captured embolic material. By correct choice of material, the same catheter or pod can be used to deploy and retrieve the filter. For deployment, the elastic material holds the filter in a tightly collapsed position to minimise the size of the catheter tip or pod. Then, when retrieving the filter, the catheter tip or pod is sufficiently elastic to accommodate the extra bulk of the filter due to the embolic material.

Also. the filter is not fast on the guidewire and thus accidental movement of the guidewire is accommodated without unintentionally moving the filter, for example, during exchange of medical devices or when changing catheters.

It will also be noted that the filter according to the invention does not have a sharp outer edge as with many umbrella type filters. Rather, the generally tubular filter shape is more accommodating of the interior walls of blood vessels.

Conveniently also when the filter has been deployed in a blood vessel, the catheter can be removed leaving a bare guidewire proximal to the filter for use with known devices such as balloon catheter and stent devices upstream of the filter.

DocumeMS

Claims (55)

1. 2. A device as claimed in claim 1, wherein the tubular filter retrieval device comprises a catheter slidable along the filter carrier, an open distal end of the catheter forming a housing for reception of the filter element.
2. 3. A device as claimed in claim 1 or 2 wherein said distal end of the retrieval device is engagable with a proximal inlet end of the filter body to close the inlet openings.
3. 4. A device as claimed in claim 1, 2 or 3 wherein said distal end of the retrieval device is slidable over the filter body from the inlet to the outlet end to progressively collapse the filter body against the tubular element and receive the filter body within the retrieval device. W shamn\DanieNSpodf\DMC 2005 200491 Sped Amencments 14dec07.dc A device as claimed in any of claims 1 to 4 wherein the tubular element 0extends longitudinally from the inlet end to the outlet end.
4. 6. A device as claimed in any of claims 1 top 5 wherein the tubular C 5 element defines a lumen therethrough, the filter carrier being extendable through the lumen to mount the filter element to the filter carrier.
5. 7. A device as claimed in claim 1 or 2 wherein the collapsible filter element is slidably mounted on the filter carrier between a pair of spaced-apart stops on the filter carrier for axial movement of the filter element along the filter Scarrier between the stops.
6. 8. A device as claimed in claim 7 wherein the tubular element is slidably mounted on the filter carrier between the stops, the length of the tubular element being less than the distance between the stops, the filter body being mounted on the tubular element.
7. 9. A device as claimed in claim 7 or 8 wherein the distal stop is located at a distal end of the filter carrier. A device as claimed in any of claims 7 to 9 wherein the distal stop comprises a spring tip.
8. 11. A device as claimed in any of claims 7 to 10 wherein the stop is formed integrally with the filter carrier.
9. 12. A device as claimed in claim 11 wherein the stop comprises a step on the filter carrier.
10. 13. A device as claimed in any of claims 7 to 10 wherein the stop is attached to the filter carrier.
11. 14. A device as claimed in any preceding claim, wherein the filter body comprises:- W:Wiamn\DanieKSpecdDMC 2005200491 Sped Amendmes 14dec07.dox 23 0 a collapsible filter net mounted on the tubular element; Sthe filter net being movable between a collapsed stored position against the tubular element and an expanded position extending outwardly of the filter carrier for deployment across a blood vessel. C A device as claimed in any preceding claim, wherein a proximal inlet end of the filter body is fixed to the tubular element.
12. 16. A device as claimed in any preceding claim wherein a distal end of the filter body is slidably mounted on the tubular element.
13. 17. A device as claimed in claim 16 wherein the distal end of the filter body is attached to a collar which is slidable along the tubular element.
14. 18. A device as claimed in any of claims 1 to 17 wherein a filter support frame is mounted on the tubular element, the support frame being movable between a collapsed position and an extended outwardly projecting position to support the filter body in the expanded position.
15. 19. A device as claimed in claim 18 wherein the filter support frame is fixed on the tubular element at a proximal end of the filter body. A device as claimed in claim 18 or 19 wherein the filter support frame slidably engages the tubular element at a distal end of the filter body.
16. 21. A device as claimed in any of the claims 18 to 20 wherein the filter support frame is biased into a normally extended position.
17. 22. A device as claimed in any of claims 18 to 21 wherein the filter support frame is formed from a shape memory or elastic memory material.
18. 23. A device as claimed in claim 22 wherein the filter support frame is formed from Nitinol. W: hmnaniePSpeadOMC 2005 200491 Sped Amnwdmerts 14dec07doc 24
19. 24. A device as claimed in any of claims 1 to 23 wherein a circumferential Sgroove is provided in the filter body intermediate the ends of the filter body. A device as claimed in any preceding claim, wherein a guide olive is provided distally of the filter body, the guide olive having a cylindrical body with a tapered distal end, the cylindrical body being engagable within a distal end of a deployment catheter, said tapered distal end projecting outwardly of the deployment catheter to provide a smoother transition between the catheter and 0the filter carrier.
20. 26. A device as claimed in any of claims 1 to 25 wherein a guide olive is provided on the filter carrier distally of the filter body, the guide olive having a cylindrical body with a tapered distal end, the cylindrical body being engagable within a distal end of a deployment catheter, said tapered distal end projecting outwardly of the deployment catheter to provide a smooth transition between the catheter and the filter carrier.
21. 27. A device as claimed in any of claims 14 to 26 wherein the net gathered into the tubular element.
22. 28. A device as claimed in any preceding claim wherein the filter element includes storage means to store captured undesired embolic material in the filter element.
23. 29. A device as claimed in any preceding claim wherein the filter element is compressible and/or foldable for loading into a delivery device to deliver the filter element to a desired location in the compressed or folded state. A device as claimed in any preceding claim wherein the filter element has material removed from its structure to provide specific sizing in relation to the size of embolic material to be trapped.
24. 31. A device as claimed in any preceding claim wherein in the expanded position the filter element has a distal end which is tapered such that there is a W:W =ror'\DamerSpea'fMC 2006 200491 Sped AIendments 14dec07,ddC smooth transition in lateral stiffness to improve the manoeuvrability of the filter Selement in the vascular system.
25. 32. A device as claimed in any preceding claim wherein the filter element C 5 has a soft distal portion to aid in atraumatic transport through the vascular system.
26. 33. A device as claimed in any preceding claim wherein the filter element has circumferential grooves to reduce the lateral flexibility of the filter element.
27. 34. A device as claimed in any preceding claim wherein in the expanded position the filter element has a tapered proximal end to facilitate retrieval by a removal catheter.
28. 35. A device as claimed in any preceding claim wherein the inlet openings are closable on pulling back of the filter element into a retrieval catheter to ensure retention of any collected emboli.
29. 36. A device as claimed in any preceding claim wherein the outlet openings are sized to capture embolic material of a size large enough to impair the function of an organ receiving blood downstream of the filter element.
30. 37. A device as claimed in claim 36 wherein the outlet openings are sized to capture embolic material of a size greater than 100 microns.
31. 38. A device as claimed in claim 36 wherein the outlet openings are sized to capture embolic material of a size greater than 200 microns.
32. 39. A device as claimed in claim 36 wherein the outlet openings are sized to capture embolic material of a size greater than 500 microns. A device as claimed in any preceding claim wherein the filter carrier comprises a medical guidewire. W:shmn\DarhSped\MC 2005 200491 Sped Amendments 14decO 0oc
33. 41. A device as claimed in claim 40 wherein the filter element is placable under a balloon or stent delivery catheter.
34. 42. A device as claimed in any preceding claim having means for insertion through femoral, brachial, radial, subclavian or other arterial puncture by means of a transcatheter approach.
35. 43. A device as claimed in any preceding claim including a delivery catheter 0in which an external sheath is engagable with the filter element to maintain the filter element in the collapsed stored position during delivery and is removable to allow movement of the filter element in the expanded position.
36. 44. A device as claimed in claim 43 wherein the external sheath is joined to the filter element or filter carrier by a joining means. A device as claimed in claim 44 wherein the joining means is a removable shrink tube.
37. 46. A device as claimed in claim 44 wherein the joining means is a removable split collar.
38. 47. A device as claimed in claim 44 wherein the joining means is a removable clip.
39. 48. A device as claimed in claim 44 wherein the joining means is a compression connector.
40. 49. A device as claimed in claim 48 wherein the compression connector is a Tuohy Borst adapter. A device as claimed in any of claims 43 to 49 wherein the delivery catheter has a central lumen for at least part of it's length to allow it to track over a steerable guidewire. WAshamronamet.SpeaADMC 2005 200491 Sped Amendmems 14decD.doc
41. 51. A device as claimed in any of claims 43 to 50 wherein the external Ssheath is sufficiently long to extend to the outside of the vasculature and is removable proximally to release the filter element from the catheter. C) C 5 52. A device as claimed in any preceding claim wherein the delivery catheter has a spring component with a localised stepwise increasing pitch to alter stiffness characteristics to suit the target vasculature.
42. 053. A device as claimed in any preceding claim wherein the delivery catheter has a spring component with a localised gradually increasing pitch to Salter stiffness characteristics to suit the target vasculature.
43. 54. A device as claimed in any preceding claim wherein the filter body is mounted on a collapsible support frame which is movable between a collapsed position for deployment and an extended in-use position, means being provided for retaining the support frame in the collapsed position. A device as claimed in claim 54 wherein the support frame comprises support arms.
44. 56. A device as claimed in claim 55 wherein the support arms are formed from a shape memory or elastic memory material.
45. 57. A device as claimed in claim 56 wherein the support arms are formed from Nitinol.
46. 58. A device as claimed in claim 57 wherein the support arms are configured to open co-axially with the filter carrier such that they may be restrained for removal by pulling the filter element proximally into an appropriately dimensioned sheath.
47. 59. A device as claimed in any of claims 54 to 58 wherein the support frame is adapted to fold into collapsed position when pulled into a retrieval catheter. W: amnDanjefSpeMD.C 200 200491 Sped Amemems 140W)7doc A device as claimed in any preceding claim wherein the filter body comprises a flexible shaped polymeric component.
48. 61. A device as claimed in claim 60 wherein the shaped polymeric component is constructed such that fluid flow through the component assists in opening the component from the collapsed position.
49. 62. A device as claimed in claim 60 or claim 61 wherein the shaped 0polymeric component is flexible and opens to make tubular contact with the (N vessel wall by way of using the pressure drop across the exit filter face.
50. 63. A device as claimed in any preceding claim wherein the filter carrier comprises a medical guidewire with a flexible segment of wire distal to the filter element so as to provide steerability of the wire particularly prior to the filter element being deployed.
51. 64. A device as claimed in any preceding claim wherein the filter carrier comprises a medical guidewire with a soft distal segment so as to provide a tip section that will be atraumatic. A device as claimed in any preceding claim wherein the filter carrier comprises a medical guidewire, the filter element being mounted to the guidewire with the guidewire in or near the outer wall of the filter body to facilitate the incorporation of one or more relatively large inlet openings at the proximal inlet end of the filter body.
52. 66. A device as claimed in claim 65 wherein the filter body has a single relatively large inlet opening at the inlet end.
53. 67. A device as claimed in claim 65 or 66 wherein the longitudinal axis of the inlet openings is offset radially from the longitudinal axis of the filter carrier.
54. 68. A device as claimed in any preceding claim wherein the distal end of the filter element has the facility to move in the axial direction relative to the W:%ha %DanBNpped\DM 2DOO 20041 Speci Amendmes I4deO7.doc 1 29 proximal end of the filter element so as to take up the exact shape of the blood Svessel.
55. 69. A filter retrieval system for use with the device as claimed in any S 5 preceding claim comprising a longitudinal catheter with a deformable tip to assist the pull back of the filter element into it. An embolic protection device, substantially as herein before described with reference to any one of the embodiments illustrated in the accompanying drawings. W.%siamnDanIeftSpeca'\MC 2005 200491 Sped Amendmems I4dec7 Soc