Vascular protection and embolic material retriever

The vascular protection and embolic material retrieval device is used in connection with a guidewire and a catheter sheath during catheter based procedures. The device includes a discontinuous loop of memory sheath material having an open loop shape when the loop is not radially restrained in the catheter sheath. When the loop is disposed beyond the distal end of the catheter sheath, the loop is deployed and forms a discontinuous loop due to the memory characteristic of the loop material. The device includes a lead line having a proximal end attached to the guidewire and a distal end attached to the discontinuous loop. A substantially conical filter adapted to capture embolic material has an open conical end attached to the discontinuous loop and a conical end point attached to the guidewire. When the loop is disposed outboard of the catheter sheath, the filter unfurls forming a conical filter trap for embolic material. In order to collapse the filter, the guidewire is pulled such that the lead line, loop and conical filter moves inboard towards the sheath's distal end and the filter collapses about any embolic material trap therein.

The present invention relates to a vascular protection and embolic material
 retriever utilized in conjunction with a guide wire utilized during
 catheterization of a patient.
 BACKGROUND OF THE INVENTION
 Vascular disease is the leading cause of death and disability in the world.
 An estimated 50 million people worldwide suffer from some form of
 coronary, cerebrovascular and/or peripheral vascular artery disease.
 Medical technology has advanced dramatically over the years, providing an
 overall decrease in the cost of care while improving a patient's quality
 of life. The primary advancement in the treatment of vascular disease has
 been the advent of catheter-based (or interventional) procedures, which
 have rapidly gained acceptance--growing from under 325,000 procedures in
 1994 to over 1,000,000 in 1997--since they are less invasive and less
 costly compared to their open surgical counterparts.
 Despite the rapid growth in catheter-based procedures, embolic events
 remain a major clinical problem. Embolic events are typically created by
 thrombus (blood clot) or plaque which break loose, enter the bloodstream,
 and become lodged in the artery resulting in the obstruction of blood
 flow.
 Stroke is a form of cardiovascular disease that interrupts blood flow to
 the brain. A stroke occurs when the carotid artery leading to the brain
 becomes clogged (ischemic stroke) or bursts (hemorrhagic stroke),
 preventing oxygen-rich blood from reaching the brain. As a result, brain
 cells die. Once dead, they do not regenerate which is why damage from a
 stroke is frequently permanent. Stroke accounts for 10% to 12% of all
 deaths in industrialized countries. For example, in a population of one
 million, 1,600 people will have a stroke each year, of which only 55% will
 survive six months post-stroke, and a third of the survivors will have
 significant disability. Stroke ranks third in terms of leading causes of
 death in the United States, behind heart disease and cancer. Strokes cause
 an estimated 150,000 deaths each year and are the leading cause of
 long-term disability. Current treatment options include medical management
 (drug therapy), carotid endarterectomy, or stent-supported carotid
 angioplasty. Carotid endarterectomy has demonstrated a marked increase in
 its use during the past two years on the basis of pivotal studies
 demonstrating a reduction in stroke after carotid revascularization. It is
 well documented that carotid endarterectomies have a 3% to 6% complication
 rate, depending if the patient is asymptomatic or symptomatic.
 Embolization has represented an obstacle to widespread acceptance of
 stent-supported carotid angioplasty due to the brain's sensitivity to even
 small amounts of emboli, with clinically significant strokes occurring in
 the absence of angiographically definable branch vessel occlusions is to
 compete effectively against the endarterectomy, it must demonstrate equal
 complication rates. In particular, carotid angioplasty must not lead to an
 increase in embolization or stroke rates. Industry sources estimate
 roughly 100,000 carotid endarterectomies were performed in the Unites
 States alone in 1997. In the same year, approximately 90,000 procedures
 were performed internationally and these operations are increasing at a
 faster rate than the United States. The desire among patients to have--and
 cardiologists to perform--less invasive procedures is evident. Industry
 estimates indicate that the number of carotid angioplasty procedures in
 the United states will grow from roughly 3,000 in 1998 to approximately
 36,000 procedures in 2002.
 The use of an effective emboli capture device or filter could significantly
 reduce the risk of these often devastating complications, and could
 potentially become the standard of care--even in low risk cases.
 During catheterization of a patient, a guide wire is directed through the
 patient's blood vessel to the site of interest. For example, the physician
 may wish to utilize a balloon catheter in order to enlarge a partially
 obstructed blood vessel at a certain location in the patient's vascular
 system. To do this, the physician utilizes a guide wire which is directed
 through the patient's vascular system to the particular site for balloon
 catheterization. Various medical devices are percutaneously inserted into
 the patient's blood vessel utilizing the guide wire. The balloon catheter,
 for example, is mounted at the distal end of an elongated tube. The guide
 wire is placed in the lumen of the balloon catheter tube such that the
 balloon catheter can be threaded over the guide wire, through the vascular
 system and placed at the site of interest by following the guide wire.
 In order to enlarge a partially obstructed blood vessel, a physician may
 use various surgical techniques and biomedical devices or tools including
 balloon catheters, scrapers or other known medical devices. However, the
 utilization of these devices sometimes results in a release of an embolus
 (embolic material) which is an abnormal particle circulating in the blood.
 In order to reduce complications arising from these medical procedures,
 physicians sometime utilize filters disposed downstream of the site of
 interest. As used herein the term "downstream" refers to an item that is
 spaced a distance apart from a referenced item and in the direction of
 blood flow through the blood vessel.
 U.S. Pat. No. 4,619,246 to Molgaard-Nielsen et al. discloses a collapsible
 filter basket. The basket includes a woven mesh but does not operate on a
 guide wire.
 U.S. Pat. No. 4,723,549 to Wholey et al. discloses a filter which is
 expanded based upon inflation of a balloon acting as a donut mounted to
 expanding frame members of the filter disposed about the guide wire.
 U.S. Pat. No. 5,053,008 to Bajaj discloses a filter which is expanded based
 upon inflation of a tubular balloon.
 U.S. Pat. No. 5,108,419 to Reger et al. discloses a filter for capturing
 particles of plaque which includes a laterally (radially) collapsible bag
 with a plurality of longitudinally displaced filter cones therein. The bag
 has a draw string about its mouth which opens and closes the bag both
 laterally (to deploy or pull-up the conical filters) and longitudinally
 (to wrap the conical filters and the bag into a small-diameter shape).
 Each conical filter includes flexible tension supports which carry filter
 screens or mesh and which open and close based upon the respective
 longitudinal position of a generally static hub at the end of a guide wire
 running through the filter basket system. In another embodiment, a single
 conical filter is utilized with a filter stocking or collapsible bag
 thereabout. All the tension supports are flexible enough to wrap and twirl
 within the collapsible bag and wrap the conical filter(s) about the guide
 wire. Also, a draw string closes the collapsible bag in all embodiments.
 The flexible tension supports or radial ribs are resilient enough to
 provide force to spread the conical filter mesh across the lumen of the
 blood vessel.
 U.S. Pat. No. 5,549,626 to Miller et al. discloses a filter deployed from
 the inside of a hollow tube by axial movement of an inner catheter. The
 filter is a mesh-like collapsible basket being made of radially expandable
 materials which can be compressed in the lumen of an outer catheter and
 radially expand when the basket extends beyond the distal end of the
 catheter.
 U.S. Pat. No. 5,695,519 to Summers et al. discloses a wire, which
 controllably moves forward and aft, to open and close a generally conical
 filter by acting on the filter's mouth.
 U.S. Pat. No. 5,810,874 to Lefebvre discloses a filter including strips
 that are radially opened by moving an inboard ring towards an outboard
 ring. The rings retain forward and aft ends of the strips. The filter can
 be detached from the guide wire.
 U.S. Pat. No. 5,814,064 to Daniel et al. discloses one filter system which
 utilizes various types of inflatable ribs, tubes or struts and a second
 filter system wherein the filter material is deployed by longitudinal
 movement of a push-pull wire relative to a generally static distal end of
 a tube (see Daniel FIGS. 15-16B). In one embodiment, struts carry filter
 mesh and are forced radially outward by axial movement of a wire attached
 to the apex of the conical filter relative to a static tube end. In a
 collapsed position, the filter is disposed outboard of the static tube. In
 another embodiment, wire filter mesh has a conical memory shape such that
 when deployed outboard of a closed end cylinder, a conical filter is
 created by the memory shaped metallic filter. In another embodiment, only
 the open end of the conical filter has a memory shape. A further
 embodiment utilizes memory shaped filter mesh, a cinch wire and a push
 guide wire.
 U.S. Pat. No. 5,911,734 to Tsugita et al. discloses a conical mesh filter
 with a proximal end strut structure connected to the distal end of a guide
 wire. Accordingly, the distal end of a guide wire is not downstream of the
 filter (see Tsugita FIGS. 2-8B). In another embodiment, the filter
 (conical or concave) is attached to radially outwardly biased struts. In a
 closed state, the biased struts are retained within a sheath. Upon axial
 movement of the guide wire relative to the sheath, the struts are moved
 beyond the sheath, they spring open to expand and deploy the filter. (See
 Tsugita FIGS. 10-11B). In a further embodiment, an egg beater filter is
 deployed. One embodiment of the egg beater filter utilizes a compressive
 spring which pulls fore and aft ends of expandable struts together,
 thereby radially expanding a filter basket with one side carrying filter
 mesh thereon. In other words, the filter is spring actuated. (Tsugita FIG.
 15A). In another egg beater embodiment, pressure wires "spring" radially
 outward deploying conical cage wires which retain a mesh filter. (Tsugita
 FIG. 16). A scroll filter is also disclosed. A further embodiment
 discloses a filter with an expansion frame apparently made of memory
 shaped material. Tsugita FIG. 19 discloses a filter with a distally
 extending inner sheath having filter strut ends attached thereto and an
 outer sheath having the other filter strut ends attached thereto. To open
 the filter, the outer sheath is moved distally towards the inner sheath
 thereby causing the filter struts to buckle radially outward. The struts
 may be packed densely to form a filter or filter mesh material may be
 draped over the struts. In a different embodiment, an outer sleeve is
 longitudinally slitted. (Tsugita FIGS. 23, 23A). When the distal end of
 the slit outer sleeve is pulled proximally, the slitted region buckles
 radially outward to provide an egg beater filter. The expanded cage can be
 draped with filter mesh.
 PCT Published Patent Application WO 96/01591 discloses a concave filter
 deployed by axially shortening the distance between the filter mouth and
 the filter apex (attached to a distal end of a guide wire). The filter
 mouth is sprung open by tethers fixed at one end to a static tube. A rod
 extends through the filter to its apex. The filter opens based upon the
 relative position of the filter apex on the rod (which extends beyond the
 apex to form the distal end of the guide wire) and the static tube.
 OBJECTS OF THE INVENTION
 It is an object of the present invention to provide a filter device for
 capturing embolic material in a blood vessel.
 It is a further object of the present invention to provide a controllably
 deployed embolic material filter and retrieval device.
 It is another object of the present invention to provide for a vascular
 protection and embolic material retriever retrieval device mounted on a
 guidewire which is movably disposed in a catheter sheath.
 It is an additional object of the present invention to provide a retrieval
 device which can remove captured embolic material from the artery of a
 patient.
 SUMMARY OF THE INVENTION
 The vascular protection and embolic material retrieval device is used in
 connection with a guidewire and a catheter sheath during catheter based
 procedures. The device includes a discontinuous loop of memory sheath
 material having an open loop shape when the loop is not radially
 restrained in the catheter sheath. When the loop is disposed beyond the
 distal end of the catheter sheath, the loop is deployed and forms a
 discontinuous loop due to the memory characteristic of the loop material.
 The device includes a lead line having a proximal end attached to the
 guidewire and a distal end attached to the discontinuous loop. A
 substantially conical filter adapted to capture embolic material has an
 open conical end attached to the discontinuous loop and a conical end
 point attached to the guidewire. When the loop is disposed outboard of the
 catheter sheath, the filter unfurls forming a conical filter trap for
 embolic material. In order to collapse the filter, the guidewire is pulled
 such that the lead line, loop and conical filter moves inboard towards the
 sheath's distal end and the filter collapses about any embolic material
 trap therein.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
 The present invention relates to a vascular protection and embolic material
 retriever.
 FIG. 1 diagrammatically illustrates a cross-sectional view of filter device
 10 generally freely traveling on guide wire 12. Filter 10 can rotate and
 move longitudinally over guide wire 12 except for longitudinal movement
 beyond stop 16 towards distal end region 14 of the wire 12. More
 importantly, the guide wire 12 moves freely through filter device 10.
 Guide wire 12 has a proximal end shown by arrow 18. Stop 16 is mounted
 near the distal end of the guide wire.
 Filter device 10 includes an expandable frame 20 formed of a plurality of
 frame struts. Frame struts 21, 23, 25 and 27 are identified in the
 cross-sectional view of FIG. 1. In a preferred embodiment, each of the
 frame struts 21, 23, 25 and 27 have a bent region 22. In a preferred
 embodiment, bent region 22 is preformed and is centrally located generally
 midway between the fore region 24 and the aft region 26 of expandable
 frame 20 on frame struts 21, 23, 25 and 27.
 In the radially deployed state, expandable frame 20 forms a pair of facing,
 frustoconical frame structures 6, 28. The mouth of frustoconical frame
 structure 6 in the illustrated embodiment is upstream of fore end 24. As
 implied earlier, the term "upstream" refers to a position opposite the
 direction of blood flow 30 shown by the single headed arrow in FIG. 1.
 Filter material 32 (typically PET material having perforations (generally
 80 holes, 400 microns each)), is attached to frame struts 21, 23, 25 and
 27 forming frustoconical frame structure 6. In FIG. 1, filter material 32
 is attached to the outside of frame struts 21, 23, 25 and 27 (FIG. 1
 representing a cross-sectional view of the deployed filter device 10). The
 aft end of filter material 32 (proximally disposed with respect to fore
 end 24 of filter device 10), has a non-perforated or drilled material
 region about bend transition region 22. This is better shown in FIG. 3
 which is discussed below. The non-perforated region enhances a sealing
 against the lumen of the blood vessel.
 One important functional feature of the present invention involves the free
 movement of guide wire 12 within and through filter device 10. This
 freedom of movement, both radially and longitudinally along the length of
 the guide wire is accomplished by fore and aft collars 11, 34 of the
 filter 10.
 FIG. 2 diagrammatically illustrates aft collar 34 movably disposed on guide
 wire 12. Similar 14 numerals designate similar items throughout the
 drawings.
 FIG. 3 diagrammatically illustrates frame strut 21 having bent transition
 region 22. Filter material 32 has a non-perforated material portion in
 bent region 22. Non-filtering region 22 generally restricts blood flow
 therethrough. This general flow resistant region 22 of material 32
 operates differently compared to blood flow region of filter 32. Blood
 flow is generally shown by arrow 30 in FIG. 1. The material utilized for
 filter 32 in the blood flow through region 33 (FIG. 3) is drilled or
 perforated. Other filters are known to persons of ordinary skill in the
 art. Generally, blood molecules flow through filter flow region of
 material 32 at region 33 but embolic material is captured by the filter
 thereat. These embolic materials are sometimes created by balloon
 catheterization, stenting or other surgical techniques acting on a
 surgical site upstream of filter device 10. This is illustrated and
 generally described later in connection with FIG. 9.
 FIG. 4A diagrammatically illustrates filter device 10 in a radially compact
 form prior to deployment of the expandable frame. Guide wire 12 includes a
 coiled tapered end 13 at distal region 14. In some situations, the end 13
 of guide wire 12 may be curved to enable the physician to better guide and
 place the guide wire in the desired vessel of the patient. See the curved
 blood vessel in FIG. 9. Filter device 10 includes a generally cylindrical
 fore end piece 40 and a tapered fore end segment 42. At aft end segment
 26, filter device 10 includes an actuation sleeve or tube 44 which extends
 in direction 18 to the proximal end of the guide wire (not shown). FIG. 4A
 also shows a further surgical instrument 48 which is utilized by the
 physician to repair, replace, mount a stent or utilize another biomedical
 structure or tool at an upstream location with respect filter device 10.
 Instrument 48 is commonly called a catheter.
 In general, the operation of filter device 10 is as follows. The physician
 deploys the guide wire 12 in the blood vessel of the patient at or near
 the surgical site of interest. Filter device 10 is customarily carried by
 guide wire 12 through the vascular system. Hence, rotational and
 longitudinal freedom of movement of filter device 10 (integrated with
 actuation sleeve 44) with respect to guide wire 12 is important. The
 filter device 10 and actuation sleeve 44 runs with guide wire 12 as an
 integrated system or unit. See FIG. 4B.
 Either before or after the physician threads or places balloon catheter or
 other surgical device 48 over the actuation sleeve 44 and hence over guide
 wire 12, the physician may radially deploy the expandable frame 10 in the
 following manner. The fore end 42 of expandable filter device 10 contacts
 stop 16 on guide wire 12. This position is shown diagrammatically in FIG.
 1. Before such contact, the physician may twist (torque) the guide wire
 through the vascular system. The guide wire freely moves rotatably and
 longitudinally through the filter device 10 (except for movement beyond
 stop 16).
 At that point in time or shortly thereafter at stop 16, the physician
 continues to exert a forward force on filter actuation tube or sleeve 44
 in the longitudinal or axial direction with respect to guide wire 12 (e.g.
 pulling the guide wire while pushing actuation tube 44) thereby causing
 compression of filter 10 and sleeve 44 and frame struts 21, 23,25, 27, 28,
 29 and 31 and causing the struts to radially expand to the position shown
 in FIG. 1. Radial expansion is limited by either the interior size of the
 blood vessel or the mechanical limits of the non-filter material about
 bent region 22. In the pre-deployed state and in a preferred embodiment,
 filter material 32 is furled within radial compact structure.
 The operation of actuation sleeve 44 and actuator piece 115 (shown in FIG.
 4B) is discussed later in detail in connection with FIGS. 15A, 15B, 16A,
 17, 16B, 16C, 18A, 18B, 18C. Alternative actuator and latch systems are
 shown in FIG. 19.
 FIG. 5 diagrammatically shows filter material 32 furled or disposed in the
 interior of the closed radially compact form of expandable frame 20. FIG.
 5 shows expandable 20 with frame struts 21, 23, 25, 27, 29 and 31.
 After deployment and formation of frustoconical frame structures 6, 28, the
 physician (a) threads device 48 (e.g. catheter 48) over guide wire 12 and
 actuation sleeve 44 and (b) activates the balloon catheter or other
 biomedical device 48 which is upstream, relative to blood flow, of the
 deployed expandable frame 10. After the surgical procedure with biomedical
 device 48, expandable frame 10 is collapsed by the physician or other
 medical technician by longitudinally pulling actuation sleeve 44 in a
 proximal direction relative to the guide wire 12. The collapse of
 expandable frame 10 is achieved by (a) temporary retention of the fore end
 40,42 of expandable frame 10 or (b) closing spring action of the frame or
 (c) both retention and closing spring action. Temporary retention of the
 frame is shown diagrammatically with certain lock or latch structures in
 FIGS. 10-12 which are discussed later. Upon collapse, filter 32 captures
 and entraps embolic material and this embolic material is withdrawn from
 the blood vessel of the patient by proximal withdrawal of actuation sleeve
 44 and expandable frame filter device 10 over guide wire 12.
 FIGS. 6A and 6B diagrammatically illustrate filter material 32 on the
 outside of frame struts 21, 23, 25, 27, 29 and 31 and on the inside of
 those frame struts, respectively.
 FIG. 6C diagrammatically illustrates filter device 10 in a radially
 deployed state. Filter material 32 has a filtering region substantially
 covering frustoconical frame structure 6. However, there is no clear
 demarcation (other than the absence of holes and passage ways) between
 filter material 32 and peripheral bend region 22 which is a non-filter
 region.
 FIG. 6D diagrammatically illustrates a plane view showing non-filter region
 22 and the filter region 33 from the perspective of a portion of section
 line D'-D" in FIG. 6C.
 FIGS. 6E, 6F and 6G diagrammatically show a scalloped edge in the
 non-filter bend region 22-22a. FIGS. 6F and 6G diagrammatically illustrate
 various collapsed states or positions for frustoconical frame structure 6.
 The utilization of scallop or concave edge regions spanning adjacent
 struts (see concave or scallop edge region 120 between the adjacent struts
 21, 31), enable the filter material 32 to furl and gather either beneath
 the frame strut (FIG. 6B) or about the frame strut (FIG. 6A) in order to
 achieve radial containment upon collapse and prior to withdrawal similar
 to that illustrated in FIG. 5. FIG. 6F diagrammatically illustrates that
 filter material 32 gathers and furls upon partial radial collapse of
 frustoconical frame structure 6 due to the concave or scallop nature of
 the material between the complementary frame struts, that is complementary
 to adjacent struts 21, 31. FIG. 6G shows that concave edge 120 promotes
 gathering of filter material 32 between the complementary frame struts
 associated with struts 21, 31. As used herein, the term "complementary
 frame struts" refers to struts attached to adjacent struts 21, 31 and
 struts which form the frustoconical frame structure 6 upon which is
 disposed filter material 32.
 FIGS. 6E, 6F and 6G diagrammatically illustrates that filter device 10 can
 be constructed to collapse and gather the filter material 32 as an
 umbrella.
 FIGS. 7 and 8A diagrammatically illustrate a cross sectional view and a
 perspective view of the deployed frame struts 21, 23,25,27, 29 and 31.
 FIG. 8A diagrammatically shows an additional frame strut 33. Accordingly,
 filter device 10 can include a plurality of frame struts if necessary.
 FIG. 8A also diagrammatically shows the bend transition region 33a for
 frame strut 33. In a preferred embodiment the frame struts are preformed
 (pre-shaped) and bent at transition region 33a such that upon axial or
 longitudinal compression between stop 16 and the proximal region of guide
 12, the frame struts expand at a predetermined common point. Preferably,
 the common point is centrally located on the struts. Preferably, the
 struts also have a "memory" which biases the struts to a closed position.
 See FIG. 4A. FIG. 8B shows a further enhancement wherein the struts are
 notched at 35a, 35b to facilitate a consistent and predictable bent region
 33a. Notches or cutouts 35a, 35b are preferably disposed at the midpoint
 of complementary frame strut members.
 FIG. 9 diagrammatically illustrates the deployed filter device 10 disposed
 in a blood vessel 90 of a patient. Guide wire 12 has been generally placed
 near the site of interest and slightly distally beyond the site of
 interest. The site of interest is partial blockage or occlusion 92 in
 blood vessel 90 of the patient. It is desirable to have guide wire 12
 move, with respect to filter 10, freely both radially and longitudinally
 except filter 10 will not move distally beyond stop 16 on guide wire 12.
 This freedom of movement (two degrees of freedom) permits the guide wire
 to move through the blood vessel 90 and particularly about blood vessel
 bend 91. In operation, the physician deploys expandable frame 10
 downstream of medical device or catheter 48 relative to blood flow 30.
 Device 48 is placed and runs over the outside of actuation tube or sleeve
 44 which is operatively associated with aft end region 26 of filter device
 10. By longitudinal compression (a force directed distally by the
 physician via actuation sleeve 44), filter device 10 radially expands
 thereby deploying filter material 32. Filter material 32 has a filter size
 (perforations or hole diameter 400 microns) adequate to capture embolic
 material which may be dislodged by the medical procedure at site 92
 upstream of filter 10. Biomedical device 48 in FIG. 9 is a general
 illustration of a balloon catheter. Actuator sleeve 44 and the collapsed
 filter device 10 easily passes within a 0.05 inch lumen of catheter 48.
 FIGS. 10-12 diagrammatically illustrate various stop configurations and
 latches to enable (a) deployment of filter material 32 and (b) collapse
 and retrieval of the filter device 10 from surgical site 92. FIG. 10
 illustrates stop 16 as a ring attached to guide wire 12. The fore end
 piece 42 of filter device 10 includes a channel 50 which is complementary
 or slightly smaller than guide ring-stop 16. When guide ring 16 is placed
 in channel 50 of fore piece 42, filter device 10 is latched onto and
 temporarily locked to guide wire 12. This latch or lock permits both
 radial deployment of filter 32 (see FIGS. 1 and 9) and also permits the
 closure of the filter by proximally moving actuation sleeve in a direction
 away from ring stop 16. This movement is relative to the guide wire.
 FIG. 11 shows a cylindrical stop 16 having a generally cylindrical body 17
 and a protruding ring 19. Fore end piece 42 of filter device 10 includes a
 complementary cavity 50, complementary to the shape of ring like
 protrusion 19 and a larger fore end cavity 51 which is complementary to
 the aft end shape of cylindrical fixed stop collar 17. The operation is
 substantially similar as that discussed above in connection with FIG. 10.
 FIG. 12 diagrammatically illustrates another configuration of stop and
 latch 16 which includes a radially inboard aft channel 13. The fore end 42
 of filter device 10 includes a protruding end piece 52 that is
 complementary to aft end channel 13 of fixed lock collar stop 16. Again,
 the physician distally moves filter device 10 until fore end key piece 52
 locks into channel 13 of collar stop 16. Further distal movement of
 actuation sleeve 44 over guide wire 12 (which is static or "not moving")
 causes radial deployment of the expandable frame struts of filter device
 10. To withdraw the filter device 10, the physician proximally pulls
 actuation sleeve 44 thereby collapsing the frame struts, collapsing the
 frustoconical frame structure 6 (FIG. 1), collapsing filter material 32
 and capturing any embolic material which did not pass through filter
 material 32. Typically, the collapse is assisted by the closing spring
 action of the frame struts. The lock and latch system consisting of
 channel 13 and key latch 52 is strong enough to result in the collapse of
 the frame strut and the filter mesh. Upon further proximal movement of
 actuation sleeve 44 and after full collapse of the expandable frame 10,
 the locking force of channel 13 and lock latch 52 is overcome by the
 pulling force of the physician, fore end latch piece 52 exits locking
 channel 13 and the filter device 10 is withdrawn from the blood vessel 90.
 FIG. 13 diagrammatically illustrates an aft end locking latch system. Aft
 end region 26 of filter device 10 includes an aft cylindrical end 55 with
 a ring collar 56. Actuation sleeve 44 includes a fore end piece 45 with a
 locking complementary channel 47 and a larger mating channel 49. Mating
 channel 49 passes over the aft end of aft member 55 of filter device 10.
 Locking channel 47 is complementary to the shape of collar protrusion 56
 thereby enabling the actuation sleeve 44 to latch onto the ring collar 56.
 In this manner, the actuation sleeve 44 can be attached and detached from
 the filter device 10. If detached, the balloon catheter or other
 biomedical device 48 travels directly over the guide wire rather than over
 actuation sleeve 44. The forces necessary to latch and unlatch the fore
 end 40, 42 of filter device 10 must be commensurate or balanced with
 respect to the locking and latching features on the aft end 55, 56 of
 filter device 10.
 In addition, FIG. 14 shows that aft end piece 55 of filter 10 can be
 threaded and carry a set of threads 60 which are complementary to thread
 set 62 on actuation sleeve 44. By locking and latching the fore end of
 filter 10 via one or more of the systems shown in FIGS. 10-12, the
 actuation sleeve 44 can be threaded onto aft piece 55 of filter device 10.
 Of course, the male and female thread features of the system shown in FIG.
 14 can be reversed such that aft 55 defines female threads and actuation
 sleeve 44 carries male threads.
 As discussed earlier in connection with FIG. 4B, filter 10 operates based
 upon longitudinal movement of actuator sleeve or tube 44. Longitudinal
 movement 112 is noted with respect to filter device 10, actuator 44 with
 respect to guide wire 12.
 It is important that the physician be notified tactilely (via touch) and
 visually that filter device 10 is approaching distal end stop 16 which is
 permanently affixed to guide wire 12. In order to provide such
 notification, FIG. 4B utilizes three temporary stops or latch points 116,
 117, 118. However, it should be noted that only a single temporary stop or
 latch point 116 may be utilized in connection with the present invention.
 FIG. 15A diagrammatically illustrates a partial, cross-sectional detailed
 view of actuator piece 115 which is part of actuator sleeve 44.
 Preferably, actuator piece 115 is cylindrical and is made with a more
 rigid material as compared with actuator sleeve 114. Most of the materials
 utilized in connection with filter device 10 and actuator sleeve 44 are
 stainless steel. Filter struts are preferably Ni Ti. Filter material 32 is
 preferably drilled (with a laser) and filter material 32 and non-filter
 region 22 is preferably made of PET. Actuator piece 115 is preferably a
 tube of NiTi. Other materials may be utilized as known to persons of
 ordinary skill in the art.
 In the illustrated embodiment of FIGS. 4B and 15A, three stops (temporary
 stops) or latch points 116, 117 and 118 are utilized. Temporary stop 118
 provides an initial indication to the physician that filter device 10 is
 soon approaching distal end stop 16. Intermediate temporary 117 is a
 tactile and a visual notice of the close approach of nose piece 42 to stop
 16.
 FIG. 15A diagrammatically shows that temporary stop 117 has a slightly
 larger outside diameter as compared with the inside diameter of actuator
 piece 115. As described later, actuator piece 115 has a longitudinal slot
 132 therethrough which permits the aft region of actuator piece 115 to
 move radially. Accordingly, the physician is permitted to hold or withdraw
 actuator piece 115 in the direction shown by arrow 112a in FIG. 15A
 thereby causing actuator piece 115 to radially expand and "jump over"
 temporary stop 117.
 FIG. 15B diagrammatically shows the slight radial overlap between temporary
 stop 116 and actuator piece 115. All latch points 116, 117, 118 have a
 similar radial relationship with respect to the interior or inner diameter
 of actuator piece 115. Accordingly, every time aft edge 134 of actuator
 piece 115 passes over temporary stop or latch points 116, 117, 118, the
 physician is tactilely notified and can visually confirm the position of
 filter device 10 in relation to distal end stop 16. By providing
 consistent, repeatable and reportable distance relationships between stops
 116, 117, 118 and the radial deployment and/or longitudinal position of
 the filter basket and distal end stop 16, the physician or the operator
 can easily control the distance and radial expansion (and contraction) of
 filter device 10 in relation to end stop 16.
 More importantly, distal end stop 116 is utilized to expand filter device
 10 as shown in FIG. 16A.
 FIG. 16A diagrammatically illustrates a radially expanded filter device 10
 which is achieved by the physician longitudinally pushing actuator sleeve
 44 such that actuator piece 115 is distally located or longitudinally
 inboard with respect to temporary stop or latch point 116. Even with
 filter 10 radially deployed as shown in FIG. 16A, the physician can easily
 rotate guide wire 12 as shown by double headed arrow 110 and also move the
 entire guide wire and temporarily latched and deployed filter 10 in the
 direction shown by double headed arrow 112a. FIG. 16A also shows that
 biomedical device or catheter 48 can be fed over temporary stops 116, 117,
 118, actuator piece 115, actuator sleeve 44 and lead to a point near the
 aft end of deployed filter device 10.
 FIG. 17 shows catheter 48 extending over actuator sleeve 44. Guide wire 12
 protrudes proximally out of the rear end of catheter biomedical instrument
 48.
 In order to radially collapse filter device 10, the physician pulls
 actuator piece 115 in the direction shown by arrow 112a in FIG. 16A
 thereby overcoming the temporary latch 116, partially radially expanding
 actuator piece 115 and longitudinally withdrawing actuator sleeve 44 with
 respect to guide wire 12. As discussed earlier, the frame struts form
 filter device 10 preferably have a memory which biases the frame struts to
 a closed position. This feature enhances closure of the filter device 10.
 FIG. 16B diagrammatically illustrates actuator piece 115 disposed at the
 proximal end of actuator sleeve 44. Actuator piece 115 includes a
 longitudinal slot 132. The proximal end 134 of actuator piece 115 is
 temporarily caught on latch point 116. It should be noted that actuator
 piece 115 may have a plurality of slots or may be made of a material which
 easily radially expands in order to overcome temporarily latch points 116,
 117, 118. Also, rather than having square peripheral edges, the latch
 point edges may be rounded. Other latch point shapes may be utilized.
 FIG. 16C provides a detailed view of slot 132 and actuator piece 115.
 FIGS. 18A, 18B and 18C diagrammatically illustrate the various positional
 aspects of actuator piece 115 in relation to critical temporary latch
 point 116. In FIG. 18A, latch point 116 is at an inboard position relative
 to actuator piece 115. The physician can easily rotate guide wire 12 in
 the direction shown by double headed arrow 110 and may also longitudinally
 move guide wire 12 in relation to filter device 10 as shown by double
 headed arrow 112. In FIG. 18B, latch point 116 is disposed beneath slot
 132. This position provides several advantages. First, the physician may
 tactilely and visually see temporary latch 116 as it travels within slot
 132. Preferably, upon visual or tactile confirmation that sleeve 115 as
 been placed such that latch 116 is adjacent slot 132, the filter device 10
 is radially deployed at various positionally related states of radial
 deployment. In other words, when actuator piece 115 is positioned such
 that temporary latch 116 is disposed at or near the inboard or distal end
 of slot 132, the frustoconical frame 6 begins to radially open filter
 material 32 (assuming that the actuator is moving distally with respect to
 a stationary guide wire). At the slot mid-point (FIG. 18B), frustoconical
 frame 6 is approximately 50% radially open. When actuator piece 115 is
 completely disposed inboard or at a distal position relative to temporary
 latch point 116 (FIG. 18C), frustoconical frame structure 6 is fully
 radially deployed.
 FIG. 20 diagrammatical illustrates actuator piece 115 having various
 indicia or markings 170, 171, 172, 173 which show and provide a visual
 indication to the physician that the filter device 10 begins its opening
 sequence (indicia 170), is 25% open (indicia 171), is 50% open (indicia
 172), is 75% open (point 173) and is fully open when proximal end 134 of
 actuator piece 115 is located at an inboard or distal position relative to
 temporary latch point 116.
 Other types of temporary latches or stops can be provided at the proximal
 end of actuator sleeve 44. For example, FIG. 19 diagrammatically
 illustrates that critical latch 116a has a male thread defined thereon and
 a proximal region 180 of actuator piece 115 has a female thread thereon.
 When the male thread of latch 116a mates with the female thread on
 proximal region 180 of actuator piece 115, filter device 10 begins to
 radially deploy. Upon rotation in a direction, for example direction 110a,
 the physician by rotating actuator piece 115 radially expands filter
 device 10 by further threading threaded member section 180 of actuator
 piece 115 over threaded latch 116a.
 In some situations, embolic material trapped in the filter may limit full
 radial closure of the filter (to a state similar to FIG. 4A). If the
 embolic material carrying filter is radially large (relative to the fully
 closed position FIG. 4A), the physician, subsequent to the withdrawal of
 the catheter, (a) places a guide wire extender on the proximal end of the
 guide wire; (b) longitudinally withdraws the actuator tube and the "full"
 filter basket while leaving the distal end of the guide wire at the point
 of interest; (c) withdraws the filter basket proximally beyond the guide
 wire extender; (d) unmounts the extender from the guide wire proper; and
 (e) proceeds with other surgical techniques (which may include the use of
 a new filter basket and/or a catheter or stent). This procedure is
 particularly useful when a stent is placed in the patient's blood vessel.
 FIGS. 21-25 diagrammatically illustrate the embolic material filter and
 retrieval device. The conical filter 220 may be similar to filter 32 in
 FIGS. 6A or 6C. The retrieval device may be used in connection with
 balloon 48 in FIG. 9. Also guide wire 204 in FIG. 21 may be extended as
 explained earlier.
 The embolic filter and retrieval device in FIG. 21 prevents embolization
 during interventional and surgical coronary and vascular procedures
 without compromising blood flow. The device is low profile as to prevent
 the dislodging of plaque or thrombus when crossing the lesion. The device
 is based on a guidewire 204 (FIG. 21) which is used to guide the operator
 to the obstructed vessel 202. The guidewire has a soft floppy tip 206 to
 prevent vessel dissection or damage. The guidewire 204 is made of a
 material to enable it to be visible under x-ray. At the distal end portion
 207 of the guidewire, a wire loop 224 is attached to act as frame for the
 filter 222. The guidewire 204 is attached to the loop 224 via led 226 then
 continues on through the center of the loop. The conical end point 300 of
 filter 222 is attached to guide wire 204. The loop 224 is made of shape
 memory alloy. The wire is trained so that it assumes a substantially round
 loop design and size in an unrestrained free state. A filter material 222
 is attached to the loop 224 by various known methods and is distally
 attached to the guidewire at cone end shape 300. The filter material 222
 allows blood to flow freely through, but traps debris, which may be
 potentially dangerous to the patient. The device 220 is introduced in the
 patient inside a tube catheter (sheath 208) to completely encase the
 distal filter 220 as shown in FIG. 21. The sheath 208 is anchored on the
 proximal portion to the guidewire with a Toughy-Borst locking mechanism
 (screw down locking device), to prevent the sheath 208 from sliding on the
 guidewire 204. Once the filter 220 is properly positioned in the vessel
 202, the protective sheath 208 is removed which allows the filter 220 to
 open conical shape filter material 222 and take shape. See FIG. 22. The
 filter opens to the internal diameter of the vessel 202 and traps any
 debris which make detach during the catheter based procedure. The device
 may also be used as a retriever of devices that may have malfunctioned or
 stones.
 Toughy-Borst locking mechanisms are described in U.S. Pat. No. 5,951,458;
 U.S. Pat. No. 5,855,546 and U.S. Pat. No. 5,484,416.
 Catheter based procedures are typically performed under fluoroscopy (x-ray)
 to help guide the user through the vasculature. The device 220 is
 introduced in the patient as an ordinary guidewire 204. The guidewire 204
 has a soft floppy tip 206 to prevent vessel dissection or damage. The
 guidewire 204 is made of a material to enable it to be visible under
 x-ray. The guidewire 204 with protective sheath 208 is introduced into
 vessel 202. The operator navigates the wire through the vessel 202 with
 the help of x-ray. Once the distal portion 207 of the guidewire 204 and
 the filter-loop 220 completely pass the obstruction in the blood vessel,
 the sheath 208 is removed or drawn proximally towards the user by
 loosening the Toughy-Borst lock down mechanism 212, and then withdrawing
 the catheter 208.
 The blood flow in direction 209 will open up the filter material 222, just
 as a parachute opens when exposed to wind. The loop 224 has a gap in one
 embodiment (see FIG. 24) and hence is discontinuous to allow the loop 224
 and filter 222 to open enough to make contact with the vessel inner wall
 202. The gap allow the loop 224 to open to various sizes. Once the
 operator removes the protective sleeve 202, a device (not shown) may be
 loaded on the guidewire. Normally a catheter with a balloon attached at
 the distal end is used. See FIG. 9. The balloon catheter (typically used
 during angioplasty) has a hollow opening to allow the catheter to be
 placed over the guidewire. The catheter is threaded over the guidewire
 204. Once the operator reaches the obstruction with the balloon, the
 balloon is inflated to push the plaque or thrombus to the sides and allow
 blood to flow unrestricted. See FIG. 9. The balloon is then deflated and
 removed. The operator can then remove the guidewire or insert a catheter
 with a stent mounted on the balloon. The catheter again is threaded over
 the guidewire. Once the balloon is inside the plaque, the balloon is
 inflated to deploy and open the stent. The stent acts as a scaffold to
 prevent the vessel from future closure. The balloon is deflated and
 withdrawn.
 Once the balloon catheter is removed, the operator is now ready to remove
 the guidewire 204. A sheath 208 is threaded over the guidewire 204 to the
 filter location. The sheath 208 has a larger opening at the distal tip 210
 to allow the filter 220 to slowly collapse and enter the catheter. See
 FIG. 23. The catheter is moved forward to allow the loop portion and the
 filter to completely enter the distal portion of the catheter. The loop
 224 is made of a material that will allow it to completely collapse. The
 filter 222 is a material, which is soft enough with minimal wall thickness
 to fold into the catheter. When the filter 220 enters the catheter, any
 debris captured is located at the distal portion of the filter, which
 prevents any debris from escaping.
 The sheath 208 is, in one embodiment, constructed of thin walled plastic in
 order to add only minimally to the guidewire/filter diameter. The sheath
 208 can be thin walled enough to allow for substantial flexibility, since
 the sheath is supported by the guidewire/filter. At the proximal end of
 the sheath a luer-lock is attached with a locking device to tighten the
 sheath over the guidewire/filter.
 The guidewire/filter is made of a proximal flexible metal wire 204 which
 then becomes tapered distally 207 with a spring wire wound around the
 tapered core wire to give the wire flexibility, steerability and
 shapeability. The guidewire distal portion 207 has a soft tip 206 so as to
 be atraumatic.
 The loop 224 is attached to the distal portion 207 via lead 226 of the
 guidewire. The loop 224 is of a smaller diameter than the guidewire 204.
 The loop 224 contains a gap in one embodiment to allow the loop to
 enlarge. The loop is made from a shape memory alloy which exhibits
 superelasticity. The wire 224 is trained so that it assumes a
 predetermined shape and size in an unrestrained free state. From this
 trained free state configuration (FIG. 22), the loop can expand to a large
 loop and contract to flat state without permanent deformation from the
 trained intermediate state. Compare FIGS. 21, 22 and 23. This range of
 movement allows the loop 224 to be easily deployed and withdrawn into the
 sheath.
 The filter material 222 is thin walled and porous to allow blood to flow
 unimpeded. The filter 222 is rolled in a cone shape with the wide portion
 attached to the loop 224 in various methods and the closed narrow portion
 attached to the guidewire. The guidewire extends continuously through the
 center of the loop and the distal center of the cone shaped filter.
 FIGS. 24 and 25 show discontinuous loops 224. In FIG. 24, loop 224 has a
 gap 232. Lead wire 226 is attached to loop 224. The other end 228 of lead
 226 is attached to guidewire 204 as shown in FIG. 22. Gap 232 creates a
 discontinuity in the substantially circular shape of loop 224. This
 discontinuity enables loop 224 to vary the size of space 230.
 In FIG. 25, the discontinuity is an inboard protruding element 250 having,
 in this embodiment, an inboard protrusion 254 directed inboard towards
 loop space 230. FIG. 25 shows an open ended triangle element 250 with an
 open side 252 outboard of loop space 230. Multiple inboard elements 250
 may be utilized. FIG. 25 also shows a second discontinuous element 260
 protruding outboard of space 230 and interposed between lead 226 and loop
 224. This outboard protruding triangular element 260 has an open end 262.
 Open end 262 may operate in a similar manner to gap 232 in FIG. 24, that
 is, to facilitate the size of loop space 230 in blood vessel 202.
 Loop 224 may be made of NITINOL or memory shaped stainless steel. Filter
 222 may be mesh or a sheet of urethane drilled with holes (typically laser
 drilled holes). A complete collapse of filter device 220 may not be
 necessary to retrieve the device. A partial collapse wherein the open end
 of conical filter 222 is near or at distal end 210 of sheath 208 may be
 acceptable.
 The claims appended hereto are meant to cover modifications and changes
 within the scope and spirit of the present invention.