Patent Publication Number: US-2003229366-A1

Title: Implantable lumen occluding devices and methods

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
     [0001] This application also claims priority to U.S. Provisional Patent Application Serial No. 60/364,439 filed on Mar. 15, 2002. This application is also a continuation-in-part of copending U.S. patent application Ser. No. 09/117,516 filed on Jan. 21, 1999 which a) is a national stage filing under 35 U.S.C. 371 of PCT/US97/01463 filed on Jan. 31, 1997, b) claims priority to U.S. Provisional Patent Application No. 60/101,614 filed on Feb. 2, 1996 and c) is a continuation-in-part of U.S. patent application Ser. No. 08/730,327 filed on Oct. 11, 1996, now abandoned and U.S. patent application Ser. No. 08/730,496 filed on Oct. 11, 1996 and now issued as U.S. Pat. No. 5,830,222. 
    
    
     
       FIELD OF THE INVENTION  
       [0002] The present invention relates generally to medical devices and methods and more particularly to implantable devices for occluding the lumens of blood vessels or other luminal anatomical structures and their methods of use.  
       BACKGROUND OF THE INVENTION  
       [0003] Implantable embolic devices are used to occlude the lumens of blood vessels or other anatomical conduits of the body. Such embolic devices have been used for a variety of therapeutic purposes. For example, certain procedures known as PICVA™ and PICAB™ are being developed by TransVascular, Inc. of Menlo Park, Calif. These procedures utilize native veins as in situ bypass conduits for diseased arteries. In such procedures, it is typically desirable to place at least one embolic blocker in the lumen of the vein into which arterial blood has been routed to in such procedures, including blocking of blood flow in veins into which arterial blood has been routed to facilitate the intended flow of arterial blood through the vein in a direction opposite normal venous flow. Examples of these PICVA™ and PICAB™ procedures are described in U.S. Pat. Nos. 5,830,222 (Makower), 6,068,638 (Makower), 6,190,353 (Makower et al.) and 6,302,875 (Makower et al.), which are expressly incorporated herein by reference.  
       [0004] Examples of some of the implantable embolic blockers of the prior art are described in U.S. Pat. Nos. 5,830,222 (Makower), 6,071,292 (Makower et al., 6,287,317 (Makower et al.) and 5,499,995 (Teirstein) as well as PCT International Publication No. Wo/97/270893 (Evard et al.), which are expressly incorporated herein by reference.  
       [0005] Although some of the embolic devices of the prior art may be useable to effectively block flow though some blood vessels or other body conduits, are remains a need in the art for the development of new implantable embolic devices and methods for catheter based, transluminal delivery and implantation of such devices.  
       SUMMARY OF THE INVENTION  
       [0006] The present invention provides an implantable embolic device for blocking the flow of body fluid through an anatomical conduit that has a wall and a lumen (e.g., blood vessel, duct, passageway, respiratory passage, bronchus, lymphatic, iatrogenically created channel or opening, shunt, etc.). In general, the implantable embolic device comprises a generally tubular, radially expandable frame member and a flexible occluder member attached to the frame member. The flexible occluder member may be formed of any suitable material, such as expanded polytetrafluoroethylene (ePTFE), that is generally in the form of a tube having an open first end and a substantially closed second end. The open first end of the flexible occluder member is affixed (or otherwise held in abutment with) to the frame member. The device is initially disposed in a first radially collapsed configuration wherein it may be transluminally advanced into the lumen of the anatomical conduit in which it is to be implanted. Thereafter, the device is expandable to a second radially expanded configuration wherein it will engage the wall of the anatomical conduit such that the closed end of the flexible member will substantially block the flow of body fluid through the lumen of the anatomical conduit. The frame member may be self-expanding or pressure expandable and may be formed of any suitable material, such as metal or plastic. In a preferred embodiment the frame is formed of a nickel titanium alloy that is superelastic at normal body temperature of 37° C. In some embodiments, the flexible occluder member may have an opening (e.g., a small hole or self-sealing opening) formed in its closed end. A catheter, guidewire or other object may be passed through such opening. Where the opening is self-sealing, the opening will resume a substantially closed configuration after such catheter guidewire or other object is removed, such that no body fluid or no more than a clinically insignificant amount of body fluid will leak though such opening. In other embodiments the opening may simply be so small in size that it the amount of body fluid that leaks through such opening is not clinically significant or does not defeat the intended embolic function of the device. Also, in some embodiments, the flexible occluder member may cover a portion of the frame adjacent its first end while a portion of the frame adjacent its second end remains uncovered. Such partially covered embodiment of the device may be implanted in the lumen of a blood vessel or other body conduit such that pressure of body fluid distal to the first end of the frame is greater than the pressure of body fluid proximal to the second end of the frame. This serves to ensure that at least the uncovered portion of the frame will remain in firm frictional engagement even if the pressure of body fluid creates some gap or space between the covered portion of the frame and the adjacent wall of the anatomical conduit. Also, in self expanding embodiments, such partial covering of the frame will allow the uncovered portion of the frame to remain expandable without being constrained or restricted by the flexible covering.  
       [0007] Further in accordance with the invention, an embolic device of the foregoing character is mounted on a delivery catheter for catheter-based transluminal delivery and implantation of the device. The delivery catheter may comprise an outer tube having a wall and a lumen and an inner tube having a wall and a lumen, with the inner tube being disposed within the lumen of the outer tube. The embolic device is mounted on the outer tube while in its first radially collapsed configuration. For embodiments where the frame is pressure expandable, a generally cylindrical balloon or other radially expandable member may be positioned on the delivery catheter beneath the embolic device to effect radial expansion and implantation of the embolic device. For embodiments where the frame is self-expanding, the embolic device may be initially loaded into the lumen of the outer tube and advanced therefrom by a pusher element or other suitable ejection apparatus. Alternatively, for self-expanding embodiments, the embolic device may be mounted about the exterior of the outer tube and one or more constraining members (e.g., a retractable sheath, severable skin or covering, retractable clip(s)s, etc.) will radially constrain the embolic device, holding it in its first collapsed configuration until such time as it is desired to allow the device to radially expand in situ to its second radially expanded configuration. In embodiments where the closed end of the flexible occluder member has an opening formed therein, a distal portion of the delivery catheter&#39;s inner tube may initially extend through such opening. A guidewire or other elongate apparatus may extend through the lumen of the inner tube to a location distal of the embolic device. Also, radiographic contrast agent, medicaments or other substances may be injected through the lumen of the inner tube. Also, in embodiments where an opening is formed in the closed end of the flexible occluder member, the embolic device may be re-traversed subsequent to its implantation by advancing a guidewire, catheter or other elongate apparatus through the opening. This may allow for performance or therapeutic or diagnostic procedures at locations distal to the implanted embolic device without requiring removal of the embolic device.  
       [0008] Further objects and aspects of the present invention will become apparent to those of skill in the art upon reading and considering the detailed description and examples set forth herebelow. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0009]FIG. 1 is a side view of one embodiment of an embolic device of the present invention.  
     [0010]FIGS. 2 a - 2   f  are a step-by-step showing of one example of a method for assembling the embolic device of FIG. 1.  
     [0011]FIGS. 3 a - 3   d  are a step-by-step showing of one example of a method for transluminal catheter based delivery of the embolic device shown in FIG. 1.  
     [0012]FIG. 3 d  is a perspective view of the embolic device of FIG. 1 implanted in the lumen of a blood vessel wherein the pressure of the blood distal to the device has created a gap between a covered portion of the device and the surrounding blood vessel wall while the uncovered portion of the device remains in abutting coaptation with the surrounding blood vessel wall. 
    
    
     DETAILED DESCRIPTION AND EXAMPLES  
     [0013] The following detailed description, and the accompanying drawings to which it refers, are provided describing and illustrating certain examples or specific embodiments of the invention only and not for the purpose of exhaustively describing all possible embodiments and examples of the invention. Thus, this detailed description does not in any way limit the scope of the inventions claimed in this patent application or in any patent(s) issuing form this or any related application. FIG. 1 shows one example of an embolic device  10  of the present invention. The embolic device  10  comprises a generally tubular frame member  12  and a flexible member  14 . The device  10  has a proximal end PE and a distal end DE. The flexible member  14  is generally in the form of a tube having an open first end  16  and a substantially closed second end  18 . The open first end  16  of the flexible member  14  is affixed to the frame member  12 , as shown.  
     [0014] The embolic device  10  is initially disposable in a first configuration (se FIG. 3 a  and the description below) wherein it may be transluminally advanced into the lumen of said anatomical conduit and subsequently expandable to a second configuration (see FIG. 3 b  and the description below) wherein it will engage the wall of an anatomical conduit in which is it positioned. When so positioned in the lumen of the anatomical conduit, the closed end  18  of the flexible member  14  will substantially occlude or block the flow of body fluid through the lumen of the anatomical conduit.  
     [0015] The frame member  12  may be formed of any suitable radially expandable material such as a metal or plastic. In a presently preferred embodiment, the frame member  12  is formed of a stainless steal that is plastically deformable. Also, in the embodiment shown in the drawings, the frame member  12  comprises a plurality of zigzag rings  25  that are connected in alignment with one another by linking segments  23 . Each zig-zag ring  25  of the frame  12  comprises a plurality of generally straight segments  22  connected to one another at angles so as to form apices  24  and troughs  26 , as shown. In some embodiments the frame member  12  may be formed of resilient material that, when unconstrained, will self-expand from the first configuration (FIG. 3 a ) to the second configuration (FIG. 3 b ). Such self-expanding embodiments of the device  10  may be mounted on or in a delivery catheter that is constructed to constrain the device in its first configuration while it is being transluminally advanced into the lumen of the body conduit and to then to allow the operator to remove the constraint from the device  10 , thereby allowing the device  10  to self-expand to its second configuration within the lumen of the anatomical conduit. In other embodiments, the frame member  12  may be formed of plastically deformable material may be expanded from its first configuration to its second configuration by exertion of outwardly directed radial force upon said frame member. Such pressure-expandable embodiments of the device  10  may be mounted on or in a delivery catheter that is equipped with a balloon or other radially expandable member useable to exert outwardly directed radial force upon the frame member  12  causing the device  10  to expand to its second configuration within the lumen of the anatomical conduit (see FIGS. 3 a - 3   b  and discussion set forth herebelow).  
     [0016] The embolic device shown in the drawings includes an optional self-sealing opening  21  formed in the closed end  18  of the flexible member  14 . A compression band  20  is positioned about the distal end of the flexible member  14  to compress it to a closed configuration. A catheter, guidewire or other elongate apparatus may be advanced through the self-sealing opening  21  during delivery of the device or after the device has been implanted in the lumen of a body conduit. The compression band is preferably formed of elastic or superelastic material (e.g., a rubber band, elastic thread(s), superelastic NiTi alloy, etc.) In the particular example shown, the compression band  20  is formed of nickel titanium alloy that is superelastic at body temperature and is generally of a zig-zag shape, as shown. The compression band  20  will dilate as a catheter, guidewire or other elongate apparatus is advance though the self-sealing opening  21 , with the flexible member  14  being firmly compressed therearound so as to deter leakage. When such catheter, guidewire or other elongate apparatus is subsequently removed from the self sealing opening, the compression band  20  will resiliently and/or elastically compress the opening  21  closed such that little or no body fluid will leak through such opening  21 . Those of skill in the art will appreciate that, in some applications, some leakage of body fluid may be acceptable or even desirable. Thus, the compression band  20  may be constructed so as not to cause complete closure of the self sealing opening  21 . In other embodiments, the self-sealing opening may be replaced by a small opening that is large enough to permit passage therethrough of a guidewire, catheter or other device but yet small enough to allow leakage of only a volume of body fluid that is not sufficiently large to defeat or substantially interfere with the intended clinical function of the device.  
     [0017]FIGS. 2 a - 2   e  show one example of a method for assembling the embolic device  10 . As shown in FIG. 2 b , a plurality of longitudinally oriented slits  28  are formed in one end of a tubular workpiece  14 ( pre ) formed of flexible material such as ePTFE. The formation of these slits  28  creates a plurality of strips  30  at one end of the workpiece  14 ( pre ), each such strip  30  having a free end  32  and an attached end  34 . In the preferred embodiment, the slits  28  extend approximately one half the length of the tubular workpiece  14 ( pre ). As shown in FIGS. 2 c  and  2   d , approximately one half of the frame member  12  is then inserted into the lumen of the tubular workpiece  14 ( pre ) and the free ends  32  of the strips  30  are passed though openings in the frame. The strips  30  are then doubled back through the lumen of the workpiece  14 ( pre ) such that the free ends  32  of the strips  30  extend beyond the first end FE of the frame  12 , as indicated by the dotted lines on FIG. 2 d . Thereafter, the compression band  20  is positioned about the tubular workpiece  14 ( pre ) at a location beyond the first end FE of the frame  12  such that the compression member will compress and anchor the strips  30  to the surrounding tubular body of the workpiece  14 ( pre ). This results in formation of the closed end  18  and the self sealing opening  21 . This also serves to soundly anchor the free ends  28  of the strips  30  such that the strips  30  do not pull back through the openings in the frame  12  and the open end  16  of the flexible member  14  is thereby affixed to the frame  12 .  
     [0018]FIGS. 3 a - 3   d  show in step-by-step fashion a method for delivery and implantation of a pressure expandable embodiment of the embolic device  10 . As shown in FIG. 3 a , the embolic device  10  is initially mounted upon a delivery catheter  40 . This delivery catheter  40  comprises an outer tube  42  which has a wall and a lumen extending longitudinally therethrough and an inner tube  44  which also has a wall and a lumen. The inner tube  44  is disposed within the lumen of the outer tube  42 . A generally cylindrical balloon  48  is mounted about the outer surface of a portion of the outer tube  42  and the embolic device  10  is mounted over the balloon  48  in its second radially collapsed configuration (FIG. 3 a ). A distal portion of the inner tube  44  extends beyond the distal end of the outer tube  42  and through the self-sealing opening  21 . A tapered region  46  may optionally be formed at the distal end of the inner tube  44  to facilitate dilation of the self-sealing opening  21  as the inner tube is advanced therethrough. Optionally, a guidewire GW or other apparatus may pass through the lumen of the inner tube  44  and out of its distal end. Also, radiographic contrast media or other substances may be injected through the lumen of the inner tube  44  before or after radial expansion of the embolic device  10 . Also, it will be appreciated that a fluid may be placed in the lumen of the inner tube and a pressure transducer may be attached to permit monitoring or pressures within the lumen L of the anatomical conduit AC.  
     [0019] The delivery catheter  40  having the embolic device  10  mounted thereon in its collapsed configuration is advanced into the lumen L of the anatomical conduit AC in which the device is to be implanted. Radiographically visible markers may be formed on the delivery catheter  40  and/or embolic device  14  to enable the operator to verify that the embolic member is at the desired position of implantation. Thereafter, the balloon  48  is inflated so as to radially expand the embolic device, as shown in FIG. 3 b . The expanded frame  12  frictionally engages the wall of the anatomical conduit AC. The balloon is then deflated and the delivery catheter  40  and any guidewire GW or other device is removed as shown in FIG. 3 c . This causes the self sealing opening  21  to close and the closed end  18  of the flexible member substantially occludes the lumen L of the anatomical conduit AC.  
     [0020] As indicated in FIG. 3 d , the pressure of body fluid within the lumen L of the anatomical conduit AC, distal to the implanted device  10 , is greater than the pressure within the lumen L proximal to the implanted device. This pressure differential causes the closed end  18  of the flexible member to invert into the interior of the frame  12 , as shown.  
     [0021] As illustrated in FIG. 3 d , in some instances, the wall of the anatomical conduit AC distal to the device  10  may dilate due to increased pressure or for other reasons. Such dilation of the anatomical conduit wall may result in formation of a gap or space  50  between the distal portion  54  of the device  10  (which is covered by the flexible member) and the adjacent wall of the anatomical conduit. However, because the frame  12  in the proximal portion  52  of the device  10  is not covered by the flexible member  14 , any body fluid that seeps from the gap  50  past the distal portion of the device  10  will pas through the openings in the uncovered frame  12  and will not result in disruption of the contact between the proximal portion  52  of the device  10  and the surrounding anatomical conduit wall. This helps to deter any migration or movement of the implanted device  10 .  
     [0022] As will be appreciated from the above-set-forth description, the embolic device  10  and methods of the present invention may provide several advantages over the prior art. For example, the embolic device  10  of the present invention causes rapid or substantially instantaneous occlusion of the vessel lumen and does not rely on changes that must occur over time, as may be the case with other approaches like glues and implantable occlusion coils. Also, a single embolic device  10  serves to occlude a vessel lumen whereas a number of coils or multiple applications of glue could be required in some cases. Also, during routine use, the over-the-wire, balloon expandable version of this device  10  does not become “free-floating” in the blood stream. The physician retains control over the device  10  either via the delivery catheter  10  or guidewire, if deployed. This approach provides a high degree of control over position of the embolic device  10  and occupies only a short length of occluded vessel as opposed to certain types of occlusion coils that may create a mass several centimeters long within a blood vessel. Also, the device  10  provides permanent occlusion of the anatomical conduit and does not tend to recannalize overtime as may occur with some other occlusion techniques.  
     [0023] Although exemplary embodiments of the invention have been shown and described, many changes, modifications and substitutions may be made by those having ordinary skill in the art without necessarily departing from the spirit and scope of this invention. For example, elements, components or attributes of one embodiment or example may be combined with or may replace elements, components or attributes of another embodiment or example to whatever extent is possible without causing the embodiment or example so modified to become unuseable for its intended purpose. Accordingly, it is intended that all such additions, deletions, modifications and variations be included within the scope of the following claims. Also, although several illustrative examples of means for practicing the invention are described above, these examples are by no means exhaustive of all possible means for practicing the invention. The scope of the invention should therefore be determined with reference to the appended claims, along with the full range of equivalents to which those clams are entitled.