Abstract:
Apparatus and methods are provided for use in deploying and retrieving a vascular device suited for filtering emboli from a vessel and performing thrombectomy and embolectomy. The vascular device comprises a support hoop having an articulation region connected near a distal end of a guide wire, and a blood permeable sac affixed to the support hoop so that the support hoop forms a mouth of the blood permeable sac. A specialized delivery system allows precise control over deployment and retrieval of the vascular device, and the introduction or withdrawal of fluids from an operative site.

Description:
REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. patent application Ser. No. 09/364,064 filed Jul. 30, 1999, now pending. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to apparatus and methods for filtering or removing matter from within a vascular system. More particularly, the present invention provides a delivery system for a low profile, self-expanding vascular device useful for capturing emboli generated during interventional procedures, and for thrombectomy and embolectomy. 
     BACKGROUND OF THE INVENTION 
     Percutaneous interventional procedures to treat occlusive vascular disease, such as angioplasty, atherectomy, and stenting, often dislodge material from the vessel walls. This dislodged material, known as emboli, enters the bloodstream, and may be large enough to occlude smaller downstream vessels, potentially blocking blood flow to tissue. The resulting ischemia poses a serious threat to the health or life of a patient if the blockage occurs in critical tissue, such as the heart, lungs, or brain. 
     The deployment of stents and stent-grafts to treat vascular disease, such as aneurysms, also involves the introduction of foreign objects into the bloodstream, and also may result in the formation of clots or release of emboli. Such particulate matter, if released into the bloodstream, also may cause infarction or stroke. 
     Numerous previously known methods and apparatus have been proposed to reduce the risk of embolism. U.S. Pat. No. 5,833,644 to Zadno-Azizi et al., for example, describes the use of balloon-tipped catheter to temporarily occlude flow through a vessel from which a stenosis is to be removed. Stenotic material removed during a treatment procedure is evacuated from the vessel before the flow of blood is restored. A drawback of such previously known systems, however, is that occlusion of antegrade flow through the vessel may result in damage to the tissue normally fed by the blocked vessel. 
     U.S. Pat. No. 5,814,064 to Daniel et al. describes an emboli filter system having a radially expandable mesh filter disposed on the distal end of a guide wire. The filter is deployed distal to a region of stenosis, and any interventional devices, such as an angioplasty balloon or stent delivery system are advanced along the guide wire. The filter is designed to capture emboli generated during treatment of the stenosis while permitting blood to flow through the filter. Similar filter systems are described in Wholey et al. U.S. Pat. No. 4,723,549 and Cassell et al. U.S. Pat. No. 5,827,324. 
     One disadvantage of radially expandable filter systems such as described in the foregoing patents is the relative complexity of the devices, which typically comprise numerous parts. Connecting more than a minimal number of such parts to a guide wire generally increases delivery complications. The ability of the guide wire to negotiate tortuous anatomy diminishes, and the profile of the device in its delivery configuration increases. Consequently, it may be difficult or impossible to use such devices in small diameter vessels such as are commonly found in the carotid artery and cerebral vasculature. Moreover, such filter devices are generally incapable of preventing material from escaping from the filter during the process of collapsing the filter for removal. 
     International Publication No. WO 98/39053 describes a filter system comprising an elongated member, a radially expandable hoop and a cone-shaped basket. The hoop is affixed to the elongated member, and the cone-shaped basket is attached to the hoop and the elongated member so that the hoop forms the mouth of the basket. The filter system includes a specially configured delivery catheter that retains the mouth of the basket in a radially retracted position during delivery. 
     While the filter system described in the foregoing International Publication reduces the number of components used to deploy the cone-shaped basket, compared to the radial strut-type filter elements described hereinabove, it too has drawbacks. Chief among these, it is expected that it will be difficult to reduce the diameter of the radially expandable hoop to its retracted position. In particular, as the hoop is contracted through smaller radii of curvature, the stiffness of the hoop is expected to increase dramatically. This increased stiffness prevents the hoop from being contracted more tightly and is expected to result in a delivery profile too large to permit use of the device in critical regions of the body, such as the smaller coronary arteries, carotid arteries, and cerebral vasculature. 
     In view of the foregoing disadvantages of previously known apparatus and methods, a need still exists for a vascular device with a reliable and multi-functional delivery system, e.g., for use as a vascular filter. It would therefore be desirable to provide a delivery system for a vascular device that overcomes the foregoing disadvantages. 
     It further would be desirable to provide a delivery system for a vascular device that integrates multiple delivery functions of previously known devices into a single device. 
     It further would be desirable to provide a delivery system for a vascular device that facilitates positioning of the vascular device in a bifurcated vessel. 
     It still further would be desirable to provide a delivery system for a vascular device that facilitates the addition or removal of fluids from the operative site. 
     It further would be desirable to provide a delivery system for a vascular device that provides precise control over the deployment and retrieval of the vascular device. 
     SUMMARY OF THE INVENTION 
     In view of the foregoing, it is an object of the present invention to provide a delivery system for a vascular device that overcomes disadvantages associated with previously known vascular filters and thrombectomy/embolectomy systems. 
     It is also an object of this invention to provide a delivery system for a vascular device that integrates multiple delivery functions of previously known devices into a single device. 
     It is another object of this invention to provide a delivery system for a vascular device that facilitates positioning of the vascular device in a bifurcated vessel. 
     It is yet another object of this invention to provide a delivery system for a vascular device that facilitates the addition or removal of fluids from the operative site. 
     It is further an object of this invention to provide a delivery system for a vascular device that provides precise control over the deployment and retrieval of the vascular device. 
     These and other objects of the present invention are accomplished by providing a delivery system for a vascular device, suitable for use as a vascular filter or thrombectomy/embolectomy device. The delivery system integrates the functions of a Touhy Borst, a torquer, and a pusher into a single device, and is configured for use with the vascular device described in commonly assigned, co-pending U.S. patent application Ser. No. 09/364,064 filed Jul. 30, 1999, which is incorporated herein by reference. 
     In a preferred embodiment, the vascular device comprises a blood permeable sac affixed at its perimeter to a support hoop having an articulation region. The reduced-thickness articulation region enables contraction of the support hoop to very small radii of curvature without increased stiffness and kinking. The hoop is attached in a distal region of an elongated member, such as a guide wire, and supports a proximally-oriented mouth of the sac when the device is deployed in a vessel. The sides of the support hoop fold inwards towards one-another when the vascular device is collapsed into a sheath for removal. This in turn closes the mouth of the sac and reduces the potential for emboli or thrombus to be released from the vascular device during removal. 
     The delivery system of the present invention facilitates introduction and retrieval of the vascular device. The torqueing function allows the vascular device to navigate tortuous anatomy. For example, the distal end of the guide wire may be rotated to selectively orient the vascular device in a selected branch of a bifurcated vessel. The Touhy-Borst adapter permits liquid to be introduced or withdrawn through the lumen of the vascular device delivery catheter. The wire feature of the delivery system allows deployment and retraction of the vascular device from within the delivery catheter. 
     Methods of using the delivery means of the present invention in conjunction with the vascular device also are provided. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objects and advantages of the present invention will be apparent upon consideration of the following detailed description, taken in conjunction with the accompanying drawings, in which like reference characters refer to like parts throughout, and in which: 
     FIGS. 1A and 1B are, respectively, a perspective view of a vascular device configured for use with the delivery system of the present invention in a deployed state, and a detailed view of the articulation region of the device of FIG. 1A; 
     FIG. 2 is a perspective view of the vascular device in a folded configuration, prior to removal; 
     FIG. 3 is a plan view of the vascular device of FIG. 1A; 
     FIGS. 4A-4D are side sectional views depicting a method of deploying, using and retrieving the vascular device; and 
     FIGS. 5A and 5B are side sectional views of a delivery system constructed in accordance with the present invention coupled to the vascular device of FIG. 4A, and show, respectively, the vascular device in the contracted and deployed states. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention is directed to a delivery system suitable for use with a vascular filter or thrombectomy/embolectomy device, such as described in co-pending, commonly assigned U.S. patent application Ser. No. 09/364,064, filed Jul. 30, 1999, incorporated herein by reference. In a preferred embodiment, the vascular device comprises a self-expanding support hoop that is sufficiently thick to radially expand and urge a blood permeable sac into engagement with a vessel wall, but which includes an articulation region that eliminates kinking. More specifically, the vascular device includes a reduced thickness articulation region and a pre-formed curved profile that avoids some of the drawbacks of previously known systems, while providing a high degree of efficacy in capturing emboli or thrombus, and ease of deployment and retrieval. In accordance with the principles of the present invention, a delivery system is provided that facilitates deployment and retrieval of the vascular device, and comprises an integrated device that performs the functions of a torquer, a Touhy Borst adapter, and a pusher. 
     Referring now to FIGS. 1A and 1B, vascular device  20 , illustratively an embolic filter, comprises guide wire  22 , support hoop  24  having articulation region  26 , and blood permeable sac  28  affixed to support hoop  24 . Sac  28  is coupled to support hoop  24  so that the support hoop forms an opening for the sac. Support hoop  24  preferably is connected to guide wire  22  near distal end  23  of the guide wire. 
     Sac  28  preferably is constructed of a thin, flexible, biocompatible material, such as polyethylene, polypropylene, polyurethane, polyester, polyethylene tetraphlalate, nylon or polytetrafluoroethylene, or combinations thereof, and includes openings or pores  30  that permit blood cells to pass through the sac substantially unhindered, while capturing any larger emboli that may be released during a procedure such as angioplasty or stent placement. 
     Support hoop  24  comprises a hoop having a circular or rectangular cross-section, and preferably is formed of a super-elastic material, such as a nickel-titanium alloy (“nitinol”). During deployment and retrieval of vascular device  20 , support hoop  24  folds in half and collapses to fit within a small diameter delivery sheath. When vascular device  20  is in a deployed state, as depicted in FIG. 2A, support hoop  24  resumes its pre-formed shape. 
     Support hoop  24  includes reduced-thickness articulation region  26  disposed opposite to point  32  at which support hoop  24  is affixed to guide wire  22 . More specifically, support hoop  24  is pre-formed to form a structure having articulation region  26  interposed between curved regions  34 . As depicted in FIG. 2B, articulation region  26  includes a region having reduced thickness t 1  compared to thickness t of the remainder of support hoop  24 . Articulation region  26  and curved regions  34  enable support hoop  24  to fold with a pre-determined shape when vascular device  20  is collapsed to a contracted state for delivery or retrieval. Support hoop  24  also may include radiopaque features, such as gold or platinum bands  33 , spaced at intervals around the circumference of support hoop  24 . 
     In a preferred embodiment, vascular device  20  fits within a delivery sheath having an inner diameter of 0.033″, and more preferably, may be used with a delivery sheath having an inner diameter as small as 0.026″. The deployed diameter of support hoop  24  preferably is approximately 7 mm, while guide wire  22  preferably has a diameter of 0.014″, and tapers at its distal end. The distal end of guide wire  22  also may be tipped with a spring section, or coil tip (not shown). 
     With respect to FIGS. 2 and 3, additional features of vascular device  20  are described. FIG. 2 depicts vascular device  20  of FIG. 1A in a contracted state, while FIG. 3 illustrates a directional change in support hoop  24  preferably caused by the presence of curved regions  34 . In the embodiment depicted in FIG.  3 , curved regions  34  illustratively are configured to orient articulation region  26  in a direction parallel to the axis of guide wire  22 . 
     Advantageously, use of articulation region  26  and the curved profile of support hoop  24  introduced by curved regions  34  cause support hoop  24  to fold in half during retrieval. As shown in FIG. 2, support hoop  24  folds in half, effectively closing the mouth of blood permeable sac  28  and preventing the escape of collected emboli or thrombus. Alternatively, articulation region  26  may comprise a gap in support hoop  24 , with blood permeable sac  28  affixed to the support hoop to bridge the gap, as described in concurrently filed U.S. patent application Ser. No. 09/470,857, now U.S. Pat. No. 6,129,739. 
     Referring now to FIGS. 4A-4D, methods of using the vascular device as a vascular filter are described. In FIG. 4A, guide wire  22  is manipulated into position within vessel V using well-known percutaneous techniques. Vascular device  20  of FIG. 1A is disposed in its contracted delivery state within distal end  42  of delivery sheath  40  and delivery sheath  40  is advanced through the vessel using distal  23  of guide wire  22 . Articulation region  26  and curved regions  34  of support hoop  24  enable the sides of the support hoop to fold together and become elongated when drawn within delivery sheath  40 . 
     With respect to FIG. 4D, once delivery sheath  40  is disposed at a desired location within a patient&#39;s vessel V, such as a coronary artery or carotid artery, for example, based on the position of radiopaque band  43  under a fluoroscope, guide wire  22  is held stationary while delivery sheath  40  is retracted proximally. Alternatively, delivery sheath  40  may be held stationary while guide wire  22  is advanced. In either case, when vascular device  20  is no longer confined within delivery sheath  40 , support hoop  24  expands so that curved regions  34  seal against the walls of the vessel V. Blood continues to flow unimpeded through vessel V in direction A. 
     In FIG. 4C, once vascular device  20  is deployed in vessel V, other interventional instruments, such as angioplasty catheters, atherectomy devices, or stent delivery systems, may be advanced along guide wire  22  to position such devices at treatment zones located proximally of vascular device  20 . For example, in FIG. 4C, angioplasty balloon catheter  44  has been advanced along guide wire  22  to a position proximal of vascular device  20  to trap emboli E, i.e., pieces of plaque dislodged from the walls of vessel V by balloon  46 . 
     With respect to FIG. 4D, upon completion of the angioplasty procedure using angioplasty balloon catheter  44 , guide wire  22  is pulled proximally to cause the sides of support hoop  24  to collapse together to close the mouth of sac  28  (see FIG.  2 ). Additional proximal retraction of guide wire  22  causes support hoop  24  and sac  28  to enter at least partially within the guide wire lumen of angioplasty catheter  44 . As depicted in FIG. 4D, only a portion of support hoop  24 , near articulation region  26 , and a distal portion of sac  28  extend out of the guide wire lumen of angioplasty catheter  44 . Angioplasty catheter  44  then is withdrawn with vascular device  20  and any trapped emboli E. 
     Alternatively, vascular device  20  may be used in performing thrombectomy/embolectomy. In this case, vascular device is deployed in a vessel at a location distal to a lesion, in the manner depicted in FIGS. 4A and 4B. Once support hoop  24  is deployed into contact with the vessel wall, vascular device  20  may be retracted proximally to scrape along the wall of the vessel, and excise thrombus so that it is captured in sac  28 . Delivery sheath  44  may then be re-inserted into the vessel along guide wire  22 , and vascular device  20  is retracted and removed from the vessel. 
     In accordance with the present invention, a delivery system is provided for use with vascular device  20  that facilitates deployment and retrieval of the vascular device. The delivery system integrates the functions of a torquer, a Touhy Borst adapter, and a pusher into a single device. 
     Referring now to FIGS. 5A and 5B, a delivery system configured for use with the vascular device of FIGS. 1-3 is described. In FIG. 5A, vascular device  20  is in the retracted state, while in FIG. 5B vascular device  20  is in the deployed state. Delivery system  50  comprises proximal screw cap  52 , collet  56 , handle  60 , rod  64 , central screw cap  68 , lumen flushing section  72 , distal hub  79 , and nose piece  86 . 
     Proximal screw cap  52  includes bore  53  with female screw thread  54  and guide wire lumen  55 . Bore  53  extends proximally from the distal face of cap  52 . Guide wire lumen  55  extends from the proximal end of bore  53  to the proximal end of cap  52 . 
     Handle  60  comprises proximal male screw thread  61  configured to engage female screw thread  54  of cap  52 , and lumen  62  configured to receive collet  56  in its proximal end and rod  64  in its distal end. Lumen  62  has a reduced diameter at the distal end of handle  60  that captures a step on the proximal end of rod  64 . Thus, while collet  56  is removable received within lumen  62 , rod  64  may translate and rotate within, but may not be removed from, lumen  62 . Guide wire  22  freely passes through collet  56  when screw cap  52  is not securely fastened to handle  60 . When cap  52  is securely fastened to handle  60 , it causes collet  56  to elastically deform, decreasing the diameter of the lumen extending through the collet, and frictionally locking guide wire  22  into rigid attachment with collet  56 . Guide wire  22  is thereby rigidly connected to handle  60 . 
     Rod  64  further comprises guide wire lumen  65  extending therethrough. Rod  64  has its distal end rigidly and permanently affixed to central screw cap  68 . Cap  68  comprises female screw thread  69  and lumen  70 . Lumen  70  includes a proximal reduced-diameter step that captures rod  64  within the proximal end of cap  68 , and a distal portion that receives lumen flushing or fluid port section  72 . 
     Section  72  comprises male screw thread  73 , side port  74 , bore  75 , guide wire lumen  76 , and fluid lumen  77 . Male screw thread  73  is configured to engage female thread  69  of cap  68 . Section  72  includes a flange disposed just distal of thread  73  that is captured within lumen  70  of cap  68 . Thus, cap  68  may be tightened onto and loosened from, but not removed from, section  72 . 
     Rod  64  is received within bore  75  of section  72 . Guide wire  22  passes between bore  75  and fluid lumen  77  within guide wire lumen  76 . Fluid lumen  77  connects side port  74  to the guide wire lumen of delivery sheath  40 . O-rings  78  provide a fluid seal at the distal end of lumen  77 . 
     Distal hub  79  connects section  72  to nose piece  86 . Hub  79  comprises bore  83 , female screw thread  84 , and annulus  85  containing tapered projection  81 . Bore  83  includes flange  82  that rotatably receives section  72  in its proximal end. Nose piece  86  comprises male screw thread  87 , tapered bore  88 , and delivery sheath lumen  89 . Male screw thread  87  is configured to engage female thread  84  in annulus  85  of hub  79 . Tapered bore  88  allows tapered projection  81  of hub  79  to extend within nose piece  86  and permit delivery sheath  40  from delivery sheath lumen  89  to extend therethrough. O-rings  78  are disposed between the hub  79  and nose piece  86  and between hub  79  and section  72 . 
     Delivery system  50  advantageously may be implemented in a variety of ways. For example, the delivery system may be offered with a delivery catheter or sheath pre-attached. In this embodiment, proximal screw cap  52  is loosened, and the proximal end of guide wire  22  may be passed through the delivery catheter or sheath, and delivery system  50 , until vascular device  20  is in its retracted state within the delivery catheter or sheath. Insertion of the vascular device into the patient may then proceed. Alternatively, delivery system  50  may be commercially supplied in the configuration shown in FIG. 5A, i.e., pre-loaded with a delivery catheter or sheath, such as sheath  40 , already attached and vascular device  20  retracted therein. As another alternative, delivery system  50  may be offered without either a delivery sheath or vascular device attached, or the delivery catheter or sheath may be an interventional instrument, such as an angioplasty, atherectomy, or stent delivery catheter. 
     Referring now to FIGS. 4A-4D and  5 A and  5 B, a method of using the delivery system of the present invention in conjunction with a vascular filter is described. With vascular device  20  contracted within distal end  42  of delivery sheath  40  (FIGS.  4 A and  5 A), delivery sheath  40  is attached to delivery system  50  by loosening proximal screw cap  52  and extending the proximal end of guide wire  22  through delivery system  50 , with handle  60  in its proximal-most position (FIG.  5 A). Screw cap  52  is then tightened to cause collet  56  to engage guide wire  22  to handle  60 . 
     Delivery sheath  40  then is advanced through a patient&#39;s vasculature using well-known percutaneous techniques using distal end  23  of guide wire  22 . If a vessel bifurcation is to be crossed during advancement, handle  60  may be rotated to divert the distal end of sheath  40  into the desired branch of the bifurcation. The rotational moment or torque applied to handle  60  is transmitted to guide wire  22  (when screw cap  52  is tightened), which causes distal end  23  to rotate and facilitates positioning of vascular device  20  in the proper side of the bifurcation. As shown in FIG. 4A, advancement continues until delivery sheath  40  is disposed at a desired location within a patient&#39;s vessel V, such as a coronary or carotid artery, as determined, for example, by the position of radiopaque band  43  under a fluoroscope. 
     With the vascular device in position, handle  60 , and thus guide wire  22 , is held stationary while the section  72  and attached delivery sheath  40  are retracted proximally. Alternatively, handle  60  may be advanced while section  72  and sheath  40  are held stationary. In either case, when vascular device  20  is no longer confined within delivery sheath  40 , support hoop  24  expands to seal against the walls of the vessel V, as depicted in FIGS. 4B and 5B. Blood continues to flow unimpeded through vessel V in direction A. 
     Depending on the medical procedure prescribed in conjunction with the use of vascular device  20 , delivery sheath  40  may retrieve vascular device  20  at the conclusion of the procedure, or sheath  40  may be detached from delivery system  50  and removed from the patient. If sheath  40  is detached, guide wire  22  may be removed from delivery system  50  so that other interventional instruments, such as angioplasty catheters, atherectomy devices, or stent delivery systems may be advanced along guide wire  22  to position such devices at treatment zones located proximally of vascular device  20 . Guide wire  22  and the interventional catheter then may be passed through and fastened to delivery system  50 . For example, as shown in FIG. 4C, angioplasty balloon catheter  44  may be advanced along guide wire  22  to a position proximal of vascular device  20  so that device  20  may trap emboli E, i.e., pieces of plaque dislodged from the walls of vessel V by balloon  46 . 
     Upon completion of the angioplasty procedure using angioplasty balloon catheter  44 , handle  60  with attached guide wire  22  is pulled proximally to cause the sides of support hoop  24  to collapse together to close the mouth of sac  28  (FIG.  2 ). Additional proximal retraction of guide wire  22  causes support hoop  24  and sac  28  to enter at least partially within the guide wire lumen of angioplasty catheter  44 . As depicted in FIG. 4D, only a portion of support hoop  24 , near articulation region  26 , and a distal portion of sac  28  extend out of the guide wire lumen of angioplasty catheter  44 . Angioplasty catheter  44  then is withdrawn with vascular device  20  and any trapped emboli E. 
     It also may be beneficial during a medical procedure to introduce or withdraw fluids from the operative site. For example, it may be beneficial to deliver medicaments, or draw suction to remove blood. The delivery sheath lumen also may require flushing with saline to prevent clotting within the lumen. These and other procedures are made possible by side port  74  of section  72 , which, as described hereinabove, is in fluid communication with the lumen of delivery sheath  40 . 
     In addition to applications with vascular filters, delivery system  50  may be used as part of the thrombectomy/embolectomy procedure described herein above, as well as in a variety of other procedures. 
     Although preferred illustrative embodiments of the present invention have been described, it will be evident to one skilled in the art that various changes and modifications may be made without departing from the invention. It is intended in the appended claims to cover all such changes and modifications that fall within the true spirit and scope of the invention.