Abstract:
Improved methods, systems and devices for occluding body passageways, particularly lung passageways. Such occlusion is achieved with occlusal stents which are particularly suited for use in performing Endobronchial Volume Reduction (EVR) in patients suffering from chronic obstructive pulmonary disease or other conditions where isolation of a lung segment or reduction of lung volume is desired. The present invention is likewise suitable for the treatment of bronchopleural fistula and potentially for other pulmonary diseases, such as hemoptysis and pneumothorax. The occlusal stents are delivered with the use of any suitable delivery system, particularly minimally invasive with instruments introduced through the mouth (endotracheally). A target lung tissue segment is isolated from other regions of the lung by deploying an occlusal stent into a target area of a lung passageway. A variety of different occlusal stent designs are provided to improve the performance and reliability of the delivered occlusal stent.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS  
       [0001]     This application is a continuation in part of U.S. Pat. No. 6,527,761 (Attorney Docket 017534-001200US), filed Oct. 27, 2000, and claims the benefit and priority of U.S. Provisional Patent Application No. 60/628,649 (Attorney Docket 017534-002000US), filed Nov. 16, 2004, the full disclosures of which is hereby incorporated by reference for all purposes. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates generally to medical devices, systems and methods. In preferred embodiments, the present invention relates to occlusal stents and methods of use for effecting lung volume reduction.  
         [0004]     Chronic obstructive pulmonary disease is a significant medical problem affecting 16 million people or about 6% of the U.S. population. Specific diseases in this group include chronic bronchitis, asthmatic bronchitis, and emphysema. While a number of therapeutic interventions are used and have been proposed, none are completely effective, and chronic obstructive pulmonary disease remains the fourth most common cause of death in the United States. Thus, improved and alternative treatments and therapies would be of significant benefit.  
         [0005]     Lung function in patients suffering from some forms of chronic obstructive pulmonary disease can be improved by reducing the effective lung volume, typically by resecting diseased portions of the lung. Resection of diseased portions of the lungs both promotes expansion of the non-diseased regions of the lung and decreases the portion of inhaled air which goes into the lungs but is unable to transfer oxygen to the blood. Lung reduction is conventionally performed in open chest or thoracoscopic procedures where the lung is resected, typically using stapling devices having integral cutting blades. Although these procedures appear to show improved patient outcomes and increased quality of life, the procedure has several major complications, namely air leaks, respiratory failure, pneumonia and death. Patients typically spend approximately 5-7 days in post-op recovery with the majority of this length of stay attributed to managing air leaks created by the mechanical resection of the lung tissue.  
         [0006]     In an effort to reduce such risks and associated costs, minimally or non-invasive procedures have been developed. Endobronchial Volume Reduction (EVR) allows the physician to use a catheter-based system to reduce lung volumes. With the aid of fiberoptic visualization and specialty catheters, a physician can selectively collapse a segment or segments of the diseased lung. An occlusal stent is then positioned within the lung segment to prevent the segment from reinflating. By creating areas of selective atelectasis or reducing the total lung volume, the physician can enhance the patient&#39;s breathing mechanics by creating more space inside the chest wall cavity for the more healthy segments to breath more efficiently.  
         [0007]     Additional improvements to EVR are desired. In particular, improved occlusal stent designs are desired which are predictably positionable, resist migration, resist leakage, and are adapted for placement within a variety of anatomies, including branched lung passageways. At least some of these objectives are met by the current invention.  
         [0008]     2. Description of the Background Art  
         [0009]     Patents and applications relating to lung access, diagnosis, and treatment include U.S. Pat. Nos. 6,709,401; 6,585,639; 6,527,761; 6,398,775; 6,287,290; 5,957,949; 5,840,064; 5,830,222; 5,752,921; 5,707,352; 5,682,880; 5,660,175; 5,653,231; 5,645,519; 5,642,730; 5,598,840; 5,499,625; 5,477,851; 5,361,753; 5,331,947; 5,309,903; 5,285,778; 5,146,916; 5,143,062; 5,056,529; 4,976,710; 4,955,375; 4,961,738; 4,958,932; 4,949,716; 4,896,941; 4,862,874; 4,850,371; 4,846,153; 4,819,664; 4,784,133; 4,742,819; 4,716,896; 4,567,882; 4,453,545; 4,468,216; 4,327,721; 4,327,720; 4,041,936; 3,913,568; 3,866,599; 3,776,222; 3,677,262; 3,669,098; 3,542,026; 3,498,286; 3,322,126; WO 98/48706; WO 95/33506, and WO 92/10971.  
       BRIEF SUMMARY OF THE INVENTION  
       [0010]     The present invention provides improved methods, systems and devices for occluding body passageways, particularly lung passageways. Such occlusion is achieved with occlusal stents which are particularly suited for use in performing Endobronchial Volume Reduction (EVR) in patients suffering from chronic obstructive pulmonary disease or other conditions where isolation of a lung segment or reduction of lung volume is desired. The present invention is likewise suitable for the treatment of bronchopleural fistula. The occlusal stents are delivered with the use of any suitable delivery system, particularly minimally invasive with instruments introduced through the mouth (endotracheally). A target lung tissue segment is isolated from other regions of the lung by deploying an occlusal stent into a lung passageway leading to the target lung tissue segment. A variety of different occlusal stent designs are provided to improve the performance and reliability of the delivered occlusal stent.  
         [0011]     In a first aspect of the present invention, an occlusal stent or device is provided comprising an expandable structure, extending between a first end and a second end along a longitudinal axis, and a covering which covers at least a portion of the expandable structure so that the expanded device occludes a body passageway. In some embodiments, the expandable structure comprises a braided material. Typically, the braided material comprises a wire, such as a superelastic wire, a shape-memory wire, a superelastic shape-memory wire, a polymer wire, a metal wire or a stainless steel wire. The covering typically comprises a membrane formed of an elastic material.  
         [0012]     In some embodiments, the structure comprises an annular shoulder, typically a substantially square shoulder near the first end, another shoulder near the second end and a contact length therebetween. Typically, at least the substantially square shoulder anchors the device within the body passageway upon expansion therein. In most embodiments, the expandable structure is symmetrical about the longitudinal axis. This is often achieved by the expandable structure having a substantially cylindrical shape surrounding the longitudinal axis. In addition, the structure may include a protrusion extending radially outwardly from the longitudinal axis beyond the substantially square shoulder. Such a protrusion may assist in anchoring the stent within the passageway.  
         [0013]     In some embodiments, the contact length curves inwardly toward the longitudinal axis. Also, the contact length may include a channel or a groove which is configured for tissue ingrowth from the body passageway. Such tissue ingrowth stabilizes the stent, resisting any possible migration, tilting or rotation within the body passageway. As described and illustrated herein below, a variety of different occlusal stent designs are provided. In some embodiments, the contact length is a first contact length and the structure includes at least one additional contact length separated from the first contact length by an additional shoulder. Further, in some of these embodiments, the first contact length is disposed at a distance from the longitudinal axis and one of the additional contact lengths is disposed at a lesser distance from the longitudinal axis so that at least the first contact length is configured to contact the body passageway upon expansion of the structure therein. In addition, any of the additional contact lengths may be substantially straight or curve inwardly toward the longitudinal axis.  
         [0014]     In another aspect of the present invention, embodiments of occlusal stents or devices are provided including a first portion comprising a radially expandable structure extending between a first end and a second end along a longitudinal axis, the structure having a substantially symmetrical cross-section which is expandable to a size wherein at least a portion of the structure contacts a wall of the body passageway within the target area anchoring the device. The device also includes a second portion comprising a radially expandable element which is expandable to a size wherein a least a portion of the element contacts a wall of the body passageway outside of the target area. A flexible portion extends between the first and second portions and a covering which covers at least part of the expandable structure of the first portion so that the first portion occludes the body passageway within the target area. Typically, the flexible portion is configured to flex so that the longitudinal axis of the first portion and the longitudinal axis of the second portion movable to any angle.  
         [0015]     In some of these embodiments, the radially expandable structure includes at least one substantially square shoulder configured to anchor the device within the target area of the body passageway. And, in some embodiments, the radially expandable structure comprises a radially expandable element extending between a first end and a second end along a longitudinal axis. The first portion and/or second portion may have a funnel shape. And, the radially expandable element may comprise a coil, a loop, or a claw, to name a few.  
         [0016]     In another aspect of the present invention, methods are provided for occluding a body passageway. One method includes providing a device comprising an expandable structure extending between a first end and a second end along a longitudinal axis, the structure having a substantially square shoulder near the first end. The device also includes a covering which covers at least a portion of the expandable structure so that the expanded device occludes the body passageway. The method further includes deploying the device within the body passageway so that the substantially square shoulder anchors the occlusal stent within the body passageway. Typically the body passageway comprises a lung passageway. In addition, deploying typically comprises expelling the device from a delivery catheter.  
         [0017]     Another method includes providing a device comprising an expandable structure extending between a first end and a second end along a longitudinal axis, the structure having at least a first contact length disposed at a distance from the longitudinal axis and a second contact length disposed at a lesser distance from the longitudinal axis, at least the first contact length contacting the body passageway upon expansion of the structure therein. The device also includes a covering which covers at least a portion of the expandable structure so that the expanded device occludes the body passageway. The method further includes deploying the device within the branched body passageway so that the first contact length is disposed within one branch of the body passageway and the second contact length is disposed within another branch of the body passageway. Typically the branched body passageway comprises a lung passageway. And, the one branch may have a larger internal diameter than the other branch. In addition, deploying typically comprises expelling the device from a delivery catheter.  
         [0018]     In another aspect of the present invention, an occlusal stent or device is provided having an expandable structure extending between a first end and a second end along a longitudinal axis, the structure having a contact length between the ends and an internal spring biased to draw the first and second ends together to expand the structure and position the contact length against the body passageway. Again, the expandable structure typically comprises a frame and the expandable structure may include a covering which covers at least a portion of the expandable structure so that the expanded device occludes the body passageway.  
         [0019]     In a further aspect of the present invention, an occlusal stent or device is provided having an expandable structure extending between a first end and a second end along a longitudinal axis, the structure having a contact length between the ends positionable against the body passageway upon expansion, and at least one anchor extending from the structure radially outwardly from the longitudinal axis to contact the body passageway upon expansion and anchor the device therein. In some embodiments, the expandable structure comprises a frame. And the device may include a covering which covers at least a portion of the expandable structure so that the expanded device occludes the body passageway. When the expandable structure comprises a braid, the anchors may be comprised of extensions of the braid. In addition, the anchors may be sharpened to penetrate the body passageway.  
         [0020]     Other objects and advantages of the present invention will become apparent from the detailed description to follow, together with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]      FIG. 1  illustrates an exemplary delivery system for delivery of an occlusal stent of the present invention.  
         [0022]      FIGS. 2-3  illustrates another exemplary delivery system for delivery of an occlusal stent of the present invention.  
         [0023]      FIG. 4  illustrates advancement of a delivery catheter into a lung passageway for delivery of an occlusal stent.  
         [0024]      FIG. 5A  illustrates a method of deployment or delivery of an occlusal stent.  
         [0025]      FIG. 5B  illustrates an embodiment of an occlusal stent comprising a coil encased in a polymer film.  
         [0026]      FIG. 6  illustrates an embodiment of an occlusal stent comprising a mesh connected to a polymer film.  
         [0027]      FIG. 7  illustrates an embodiment of an occlusal stent comprising a barb-shaped structure.  
         [0028]      FIG. 8  illustrates an embodiment of an occlusal stent having a cylindrical-type balloon with textured friction bands.  
         [0029]      FIG. 9  depicts an embodiment of an occlusal stent comprising a multi-layer balloon which has an adhesive material between an outer layer and an inner layer of the balloon.  
         [0030]      FIG. 10  illustrates an embodiment of an occlusal stent which is similar to that of  FIG. 9 , including openings in the outer layer through which adhesive may seep.  
         [0031]      FIGS. 11A-11B  illustrate a braid fabricated on a mandrel which is used to form some embodiments of the occlusal stent.  
         [0032]      FIGS. 12A-12C  illustrate an embodiment of an occlusal stent having square shoulders.  
         [0033]      FIG. 13  illustrates tissue remodeling forming a pocket around an occlusal stent.  
         [0034]      FIG. 14  illustrates a stent positioned within a branched area of a lung passageway forming a pocket by tissue remodeling.  
         [0035]      FIG. 15  illustrates target areas within branchings of a lung passageway.  
         [0036]      FIG. 16  illustrates recoiling of an occlusal stent causing leakage thereby.  
         [0037]      FIG. 17  illustrates a recoiled occlusal stent partially within a branched lung passageway allowing leakage thereby.  
         [0038]      FIG. 18A-18B ,  19 A- 19 B illustrate an embodiment of an occlusal stent having a square shoulder and a sloping shoulder.  
         [0039]      FIG. 20  illustrates recoiling of an occlusal stent such as shown in  FIG. 18A  positioned within a branched passageway.  
         [0040]      FIGS. 21A-21B ,  22 A- 22 B illustrate embodiments of an occlusal stent having contact lengths disposed at differing diameters.  
         [0041]      FIG. 23  illustrates positioning of an occlusal stent, such as shown in  FIG. 21A , partially within a branched lung passageway.  
         [0042]      FIGS. 24A-24B ,  25 A- 25 B,  26  illustrate embodiments of an occlusal stent having a channel within a contact length.  
         [0043]      FIGS. 27A-27N  illustrate additional embodiments of occlusal stents having differing configurations.  
         [0044]      FIG. 28  illustrates an embodiment of an occlusal stent of the present invention having a gradual taper.  
         [0045]      FIG. 29  illustrates an embodiment of an occlusal stent of the present invention having a light-bulb shape.  
         [0046]      FIGS. 30-33  illustrate occlusal stents having a first end which is positionable within a target lung passageway and a second end which is positionable within a branched lung passageway.  
         [0047]      FIGS. 34A-34B  illustrate an embodiment of an occlusal stent having a round ball-shape.  
         [0048]      FIGS. 35A-35B  illustrate an embodiment of an occlusal stent having a non-occlusive second end in the form of a coil.  
         [0049]      FIGS. 36A-36B  illustrate an embodiment of an occlusal stent having a non-occlusive second end in the form of a loop.  
         [0050]      FIGS. 37A-37B  illustrate an embodiment of an occlusal stent having a non-occlusive second end in the form of a claw.  
         [0051]      FIGS. 38A-38C  illustrate an embodiment of an occlusal stent which expands during inspiration and retracts during expiration.  
         [0052]      FIGS. 39A-39B  illustrate an embodiment of an occlusal stent having spikes.  
         [0053]      FIGS. 40A-40B  illustrate an embodiment of an occlusal stent having wings.  
         [0054]      FIGS. 41A-41B  illustrate an embodiment of an occlusal stent having a conformable non-rigid cross-section.  
         [0055]      FIG. 42  illustrates an embodiment of an occlusal stent having a first covering which covers one end of the stent and a second covering which covers the opposite end of the stent.  
         [0056]      FIGS. 43A-43B  illustrate an embodiment of an occlusal stent having an internal spring.  
         [0057]      FIGS. 44A-44D  illustrate embodiments of an occlusal stent having anchors. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0058]     Endobronchial Volume Reduction (EVR) is performed by collapsing a target lung tissue segment, usually within lobar or sub-lobular regions of the lung which receive air through a single lung passage, i.e., segment of the branching bronchus which deliver to and receive air from the alveolar regions of the lung. Such lung tissue segments are first isolated and then collapsed by aspiration of the air (or other gases or liquids which may be present) from the target lung tissue segment. Lung tissue has a very high percentage of void volume, so removal of internal gases can reduce the lung tissue to a small percentage of the volume which it has when fully inflated, i.e. inflated at normal inspiratory pressures. Evacuation of the target lung tissue segment is maintained by positioning of an occlusal stent therein.  
         [0059]     Isolation and delivery of the occlusal stent may be achieved with the use of a variety of instruments. A few exemplary embodiments of delivery systems are provided herein, however it may be appreciated that any suitable delivery system may be used to deliver the occlusal stents of the present invention.  
         [0060]     In addition, it may be appreciated that although the occlusal stents are described herein in relation to use in lung passageways, the occlusal stents may be used within any body passageways.  
         [0000]     Delivery Systems  
         [0061]     A first exemplary delivery system  10  is illustrated in  FIG. 1  and further described in U.S. Provisional Patent Application No. 60/628,856, filed Nov. 16, 2004, assigned to the assignee of the present invention and incorporated by reference for all purposes. As shown, the system  10  comprises a bronchoscope  12  having a proximal end  14 , a distal end  16  and at least a working lumen  18  extending from the proximal end  14  to the distal end  16 . In addition, the bronchoscope  12  typically includes an imaging system  20  extending from the proximal end  14  to the distal end  16 . The imaging system  20  may include an imaging lens near the distal end  16  and fiber bundles which extend from the imaging lens to the proximal end  14 . The fiber bundles may be coupled to a monitor so that images from the distal end  16  of the bronchoscope  12  may be transmitted and viewed on the monitor. Further, light fibers  22  may extend to the distal end  16  for illumination. Also, one or more lumens may extend therethrough, such as for aspiration. Alternately the imaging system may include a miniature camera at the tip.  
         [0062]     The bronchoscope  12  also includes a handle  24  disposed near the proximal end  14 . The handle  24  is formed to include a sidearm  24   a  which provides access to the working lumen  18 . The handle  24  also includes a connector  28  which permits attachment to an external viewing scope. It may be appreciated that the bronchoscope  12  included in this embodiment of the system  10  of the present invention may be comprised of any suitable bronchoscope, including conventional bronchoscopes. However, it may also be appreciated that other instruments or catheters may be used which provide viewing or visualization capabilities.  
         [0063]     In this embodiment, the system  10  also includes a sheath  30  having an occlusive member  32  disposed near its distal end, a full description of which is provided in U.S. Pat. No. 6,585,639 [Attorney Docket No. 017534-001300US], assigned to the assignee of the present invention and incorporated by reference for all purposes. The sheath  30  includes a flexible tubular body having a distal end and an occlusive member  32  disposed at or near the distal end of the tubular body. Typically, the occlusive member will be formed from an inflatable elastomeric material which, when uninflated, lies closely over an exterior surface of the distal end of the flexible tubular body. Upon inflation, the material of the occlusive member will simply stretch and permit radial expansion. The elastic nature of the member will permit the member to conform to irregular geometries of a target lung passageway to provide for effective sealing.  
         [0064]     The system  10  of  FIG. 1  also includes an occlusal stent delivery catheter  40  which is positionable within the working lumen  18  of the bronchoscope  12 . The catheter  40  comprises a tubular shaft  41  having a distal end  42 , wherein the distal end  42  is extendable beyond the distal end  16  of the scope  12 . This may be achieved by slidably advancing the catheter  40  within the working lumen  18 . The catheter  40  also includes a positioning rod  44  that is disposed within the tubular shaft  41 . The positioning rod  44  is used to position and unsheathe the stent or to expel an occlusal stent  46  from the distal end  42  of the catheter  40 . The catheter  40  is positionable within the working lumen  18  of the scope  12  by advancement through the sidearm  24   a  of the handle  24 .  
         [0065]     The catheter  40  also includes a handle  48  which remains outside of the sidearm  24   a . Both the tubular shaft  41  and the positioning rod  44  are attached to the handle  48  so that gross movement of the handle  48  toward or away from the sidearm  24   a  advances or retracts the catheter  40  within the working lumen  18 . To assist in positioning the catheter  40  within the working lumen  18  and to lock portions of the catheter  40  in relation to the scope  12 , a clamp connector  60  may be used. The clamp connector  60  may be joined with the sidearm  24   a  by a quick connector  62 , however any connecting mechanism may be used. The catheter  40  is advanceable through the clamp connector  60  and the handle  48  is lockable to the clamp connector  60  by a locking mechanism  64 .  
         [0066]     The positioning rod  44  is fixedly attached to the handle  48  and the tubular shaft  41  is slidably attached to the handle  48 . Thus, locking of the handle  48  to the clamp connector  60  using locking mechanism  64  in turn locks the positioning rod  44  in relation to the scope  12 . The tubular shaft  41  may then be slidably advanced or retracted in relation to the scope  12  and the positioning rod  44  by movement of a handle button  50  on the handle  48 . The handle button  50  is fixedly attached to the tubular shaft  41 . In this manner, the tubular shaft  41  may be retracted to deploy the occlusal stent  46 .  
         [0067]     A second exemplary delivery system is illustrated in  FIGS. 2-3  and further described in U.S. Pat. No. 6,527,761, assigned to the assignee of the present invention and incorporated by reference for all purposes. The delivery system comprises an access catheter  100  having a catheter body  112  which has a distal end  114 , a proximal end  116 , and at least one lumen therethrough. In this embodiment, the catheter  100  further comprises an inflatable occlusion balloon  118  near its distal end  114 . Thus, the catheter has at least two lumens, a central lumen  120  and a balloon inflation lumen  122 . As shown in  FIG. 3 , the balloon inflation lumen  122  may be an annular lumen defined by inner body member  124  and outer body member  126  which is coaxially disposed about the inner body member. The lumen  122  opens to port  130  on a proximal hub  132  and provides for inflation of balloon  118 . The central lumen  120  opens to port  136  on hub  132  and provides for multiple functions, including optional introduction over a guidewire, aspiration, introduction of secondary catheters, and the like.  
         [0068]     Optionally, the access catheter  100  can be provided with optical imaging capability. Forward imaging can be effected by illuminating through light fibers which extend through the catheter  100  and detecting an image through a lens at the distal end of the catheter  100 . The image can be displayed on conventional cathode-ray or other types of imaging screens. In particular, as described below, forward imaging permits a user to selectively place the guidewire for advancing the catheters through a desired route through the branching bronchus.  
         [0069]     Referring to  FIG. 4 , the catheter  100  can be advanced to a lung tissue segment, specifically a diseased region DR, within a lung L through a patient&#39;s trachea T. Advancement through the trachea T is relatively simple and may employ an endotracheal tube and/or a guidewire to select the advancement route through the branching bronchus. Steering can be effected under real time imaging using imaging. Optionally, the access catheter  10  may be introduced through a visualizing tracheal tube, such as that described in U.S. Pat. No. 5,285,778, licensed to the assignee of the present application, and incorporated by reference. It may be appreciated that the access catheter may be positioned with or without the use of a trachea tube or similar device.  
         [0070]     Once the distal end  114  of the access catheter  100  is positioned in a desired location within the lung passageway, an occlusal stent or obstructive device may be deployed in the passageway. Typically, the occlusal stent is housed within the access catheter  100  or within a catheter that may be passed through the access catheter  100 . The occlusal stent is compressed or collapsed within an interior lumen of the access catheter  100 . The occlusal stent may then be pushed out of the distal end  114  of the catheter  100  into the lung passageway, or alternatively can be unsheathed by retracting the catheter. If the occlusal stent is self-expanding, for example by tension or shape-memory, the stent will expand and anchor itself in the passageway. If the occlusal stent is not self-expanding, it may be expanded with the use of a balloon or other mechanism provided by the access catheter  100 , a catheter or device delivered through the access catheter  100 , or another device.  
         [0000]     Occlusal Stents  
         [0071]     The occlusal stents  46  of the present invention may be delivered with any suitable delivery system, particularly the systems described above. The occlusal stents  46  described herein represent exemplary embodiments and are not intended to limit the scope of the invention.  
         [0072]     A variety of exemplary embodiments of occlusal stents are described and illustrated in U.S. Pat. No. 6,527,761, assigned to the assignee of the present invention and incorporated by reference for all purposes. The occlusal stent, such as an obstructive device or a blockage device, is deployed and anchored within a lung passageway leading to a lung tissue segment and is left as an implant to obstruct the passageway from subsequent airflow. An example of such an occlusal stent  46  is illustrated in  FIGS. 5A-5B .  
         [0073]     As described previously, the occlusal stent  46  may be housed within the access catheter  10  or within a catheter that may be passed through the access catheter  10 . As depicted in  FIG. 5A , the occlusal stent  46  may be compressed or collapsed within an interior lumen of the access catheter  10 . The occlusal stent  46  depicted here is one of many designs which may be utilized. The occlusal stent  46  may then be pushed out of the distal end  16  of the catheter  10 , in the direction of the arrow, into the lung passageway  152 , or alternately, the stent can be unsheathed by retracting the catheter  10 . In this embodiment, the stent  46  is to be self-expanding by tension or shape-memory so that it will expand and anchor itself in the passageway  152 .  
         [0074]     Referring to  FIG. 5B , one embodiment of the occlusal stent  46  comprises a coil  282 . The coil  282  may be comprised of any type of wire, particularly superelastic and/or shape-memory wire, polymer or suitable material. The tension in the coil  282  allows the stent  46  to expand to fill the passageway  152  and rest against the walls of the passageway  152  to anchor the stent  46 . In addition, the coil  282  may be connected to a thin polymer film  284 , such as webbing between the coils, to seal against the surface of the lung passageway  152 . Such a film  284  prevents flow of gases or liquids through the coils, thereby providing an obstruction. Alternatively, as depicted in  FIG. 5B , the coil  282  may be encased in a sack  286 . Expansion of the coil  282  within the sack  286  presses the sack  286  against the walls of the passageway  152  forming a seal. Again, this prevents flow of gases or liquids, depicted by arrows, through the coil  282 , thereby providing an obstruction. Similarly, as depicted in  FIG. 6 , another embodiment of the occlusal stent  46  comprises a mesh  283 . The mesh  283  may be comprised of any type of wire, particularly superelastic and/or shape-memory wire, polymer or suitable material. Alternately, the mesh can be another form of non-wire scaffolding such as strips, tubes or struts to name a few. The tension in the mesh  283  allows the stent  46  to expand to fill the passageway  152  and rest against the walls of the passageway  152  to anchor the stent  46 . In addition, the mesh  283  may be connected to a thin polymer film  284 , such as webbing between the lattice of the mesh, to seal against the surface of the lung passageway  152 . Such a film  284  prevents flow of gases or liquids through the mesh, thereby providing an obstruction.  
         [0075]     Referring now to  FIG. 7 , another embodiment of the occlusal stent  46  comprises a barb-shaped structure  304  designed to be wedged into a lung passageway  152  as shown. Such a structure  304  may be comprised of a solid material, an inflatable balloon material, or any material suitable to provide a blockage function. The structure  304  may be inflated before, during or after wedging to provide sufficient anchoring in the lung passageway. Similarly, the structure  304  may be impregnated or infused with an adhesive or sealant before, during or after wedging to also improve anchoring or resistance to flow of liquids or gasses through the passageway  152 .  
         [0076]     Referring to  FIG. 8 , another embodiment of the occlusal stent  46  comprises an inflated balloon. Such a balloon may take a number of forms. For example, the balloon may have take a variety of shapes, such as round, cylindrical, conical, dogboned, or multi-sectional, to name a few. Or, a series of distinct or interconnected balloons may be utilized. Further, the surface of the balloon may be enhanced by, for example, corrugation or texturing to improve anchoring of the balloon within the lung passageway.  FIG. 8  illustrates a cylindrical-type balloon  300  with textured friction bands  302  which contact the walls of the lung passageway  152  when the balloon  300  is inflated as shown.  
         [0077]     It may be appreciated that such balloons may be inflated with any number of materials, including saline, gas, suitable liquids, expanding foam, and adhesive, to name a few. Further, a multi-layer balloon  310  may be utilized, as shown in  FIG. 9 , which allows the injection of adhesive  312  or suitable material between an outer layer  314  and an inner layer  316  of the balloon  310 . Such adhesive  312  may provide a hardened shell on the obstruction stent  46  to improve its obstruction abilities. As shown, the balloon  310  may be inflated within the inner layer  316  with a foam  318  or other material. Similarly, as shown in  FIG. 10 , the outer layer  314  of the occlusal stent  46  may contain holes, pores, slits or openings  320  which allow the adhesive  312  to emerge through the outer layer  314  to the outside surface of the multi-layer balloon  310 . When the balloon  310  is inflated within a lung passageway  152 , the outer layer  314  of the balloon  310  will press against the walls of the passageway  152  and the adhesive  312  will bond with the walls in which it contacts. Such adhesion is designed to improve anchorage and obstructive abilities of the occlusal stent  46 .  
         [0078]     It may also be appreciated that the above described blockage devices may be impregnated, coated or otherwise deliver an antibiotic agent, such as silver nitrate. Such incorporation may be by any means appropriate for delivery of the agent to the lung passageway. In particular, a multi-layer balloon may be provided which allows the injection of an antibiotic agent between an outer layer and an inner layer of the balloon  310 . As previously described and depicted in  FIG. 10 , the outer layer  314  of the occlusal stent  46  may contain holes, pores, slits or openings  320  which allow the agent to emerge through the outer layer  314  to the outside surface of the multi-layer balloon  310 . Thus, the agent may be delivered to the walls and/or the lung passageway.  
         [0079]     It may further be appreciated that the occlusal stent  46  may comprise a variety of designs having various lengths and shapes. In addition, many embodiments of occlusal devices or obstructive devices described and illustrated as having a port for aspiration therethrough (described and illustrated in U.S. Pat. No. 6,527,761 [Attorney Docket No. 017534-001200US]) may either have no port, a sealed port or a port which is not accessed for aspiration, for example a port for drug delivery, fluid removal, inspection, etc.  
         [0080]     In many further embodiments, the occlusal stent  46  is comprised of a structure, such as a braid. As illustrated in  FIG. 11A  the braid  400  is fabricated on a mandrel  403  having a diameter close in size to the desired diameter of the occlusal stent  46  when unrestrained or in free space. The unrestrained diameter of the stent  46  is typically desired to slightly exceed the internal diameter of the bronchial tube within which it will be placed. Thus, the diameter of the braid  400  may vary depending on the intended usage of the stent  46 .  FIG. 11B  provides a cross-sectional view of  FIG. 11A . Alternately, the unrestrained diameter of the stent can be designed to substantially exceed the internal diameter of the target bronchial tube, for example 100% larger.  
         [0081]     The braid  400  may be comprised of any type of wire, particularly superelastic and/or shape-memory wire, polymer or suitable material. In some embodiments, the braid is comprised of 0.006″ Nitinol wire (30-45% CW, oxide/etched surface). The wire braid  400  can be woven from wires having the same diameter, e.g. 24 wires each having a 0.006″ diameter, or wires having varied diameters, e.g. 12 wires each having a 0.008″ diameter and 12 wires each having a 0.003″ diameter. Other numbers of wires and combinations of wire diameters can also be used. In addition to the above, variation in the configuration of braid pattern, e.g., one over one under, one over two under or two over two under and the braid angle, eg., between 60 and 90 degrees can be used or applied. Example dimensions and configurations are provided in Table A.  
                                                     TABLE A                                       BRAID               CONFIGURATION   BRAID                    MANDREL   NO. OF       ANG.       NO.   WIRE DIA.   DIA.   WIRES   PATTERN   (REF.)               1   Ø.0060 ± .0003″   Ø.375″   24   1 over   60°                       1 under       2   Ø.0060 ± .0003″   Ø.438″   24   1 over   70˜75°                       1 under                  
 
         [0082]     Once the braid has been fabricated, the braid is then cut to an appropriate length and shape-set to a desired configuration by heat treatment. The desired configuration generally comprises the ends of the cut length of braid  400  collapsed to form ends or tails, which are secured and covered by bushings, and a portion therebetween having an overall shape conducive to occluding a lung passageway. Such heat treatment may comprise heating the braid  400  at a predetermined temperature for a period of time. When other materials, such as Elgiloy® and stainless steel, are used, the wire is formed into the desired configuration using methods different from shape setting methods used for shape memory alloys. After shape-setting, the braid may then be etched to remove oxidation.  
         [0083]     The desired configuration may include a variety of overall shapes, each allowing the stent  46  to perform differently or occlude lung passageways of differing shapes, sizes and configurations.  FIG. 12A  is a side view of one embodiment of an occlusal stent  46 . The stent  46  comprises a braid  400  formed into a cylindrical shape which extends along a longitudinal axis  404 . The braid  400  is collapsed to form ends or tails which are secured and covered by bushings  401 . The stent  46  also includes a covering  405 . The covering  405  may cover any portion of the braid  400 , including encapsulating the entire stent  46 . However, in preferred embodiments, the covering  405  covers at least one end of the stent  46  and wraps around at least one shoulder  402  to create a seal when the stent  46  positioned within a lung passageway.  FIG. 12A  illustrates the covering  405  extending around the stent  46  leaving an opening  407  at one end of the stent  46 . Such an opening  407  facilitates collapsing of the stent  46  for loading in a catheter by allowing any air within the stent  46  to be expelled through the opening  407 .  
         [0084]     The covering  405  may be comprised of any suitable material. Typically, the covering  405  is comprised of a membrane of an elastic material of high elongation, such as greater than approximately 200-300% elongation. Example materials include silicone, polyurethane, or a co-polymer, such as a mixture of silicone and polyurethane. Other elastic materials may also be used. In some embodiments, the membrane material is prepared as a solution and then de-aired to remove potential air bubbles. The stent  46  is then dipped into the solution to coat the appropriate portions of the braid  400 . The stent  46  is then cured so that the coated solution forms the membrane covering  405 . In some embodiments, the covering  405  has a thickness of 0.002±0.0005 inches and is able to withstand air pressure of a minimum of 3 psi without leakage. However, it may be appreciated that any suitable thickness and air pressure tolerances may be used. In some embodiments, the covering  405  has radiopaque qualities to provide visibility of the covering with the use of fluoroscopy or any other suitable visualization technique. Also, in some embodiments, the covering  405  is impregnated, coated or contains a drug or other agent which may be eluted into the surrounding tissue or lung passageway.  
         [0085]     The occlusal stent  46  of  FIG. 12A  has shoulders  402  which are at an angle which is approximately 90 degrees to the longitudinal axis  404  of the stent  46 . In this embodiment, the stent  46  has an overall length L along longitudinal axis  404  of approximately 14.3±0.3 mm and a maximum diameter of 10.2±0.2 mm. Here, the length of the stent  46  between the shoulders  402  (the contact length CL) is approximately 8.1±0.1 mm. It may be appreciated that dimensions of the occlusal stent  46  in this and other embodiments are for example only and are not intended to limit the scope of the invention; any suitable dimensions may be used. Thus, the squareness of the shoulders  402  maximizes the contact length CL of the stent  46  which allows maximum contact surface area of the length of the stent  46  with the lung passageway. This is useful when placing the stent  46  into short bronchial segments or take-offs.  FIG. 12B  is an end view of the embodiment shown in  FIG. 12A .  FIG. 12C  illustrates the stent  46  of  FIG. 12A  positioned within a lung passageway LP. As shown, the stent  46  has been expelled from the distal end  42  of a delivery catheter  40  within the lung passageway LP. The stent  46  expands to fill the passageway LP, either by self-expansion or by assisted expansion. The radial force will be sufficient to push the covering  405  against the walls of the lung passageway LP to create an effective seal. The radial hoop force also reduces migration of the occlusal stent  46 . Once the stent  46  is deployed, a visual inspection of the stent  46  placement may be performed, such as with the use of fiberoptics. If desired, the stent  46  may be manipulated and repositioned. In addition, if desired, the stent  46  may be removed, either immediately or within several weeks of the initial deployment. In some situations, the stent  46  may also be removed at points in time thereafter.  
         [0086]     While the stent  46  remains positioned within the lung passageway LP, the stent  46  continues to exert a desired force against the walls of the passageway LP. The force is selectively designed such that it is not too high to tear or traumatize the tissue, but not too low that could permit stent migration. Consequently, the tissue receiving the force undergoes tissue remodeling and the passageway LP expands in the area of the stent  46  over time. This phenomenon is illustrated in  FIG. 13  wherein the passageway LP is shown to be widened along the contact length CL of the occlusal stent  46  forming an indentation or pocket. Such widening may continue until the stent  46  is fully expanded due to the properly selected forces. Thus, the occlusal stent  46  does not exert long term pressure on the walls of the lung passageway LP. The formation of a pocket may serve beneficial purposes, such as holding the stent  46  in place and resisting migration of the stent  46  along the passageway LP. The pocket formed in  FIG. 13  is located along a straight segment of passageway LP.  FIG. 14  illustrates a stent  46  positioned within a branched area of a lung passageway LP wherein the pocket is formed where the stent  46  contacts the walls of the passageway LP. As shown, contact length CL 1  is longer than contact length CL 2  due to the branching of the passageways. However, the stent  46  is still able to maintain blockage of the passageway LP.  
         [0087]     In some instances, as illustrated in  FIG. 15 , the branchings of the lung passageways LP are so close together that the target lung passageways (indicated by dashed circles  500 ) are considerably short. In  FIG. 15 , a lobar bronchus LB branches into sub-segmental bronchi SSB. Here, the target areas or target lung passageways  500  are within a segmental bronchus SB. This can create a number of challenges when positioning occlusal stents  46  within the target lung passageways. For example, as illustrated in  FIG. 16 , the occlusal stent  46  may be positioned partially within the lung passageway LP and partially within one of the branched lung passageways BLP to block the passageway proximal to the branch. In this embodiment, the stent  46  has square shoulders  402  near both bushings  401 . Once positioned, the stent  46  may relax and recoil within the lung passageway LP. When the stent  46  has a uniform shape, such as illustrated in  FIG. 12A , the stent  46  may recoil substantially uniformly, as indicated by dashed line. In some instances, this may allow leakage of gasses by the shoulder  402  in the opposite branched lung passageway BLP′, as indicated by arrow A.  FIG. 17  also illustrates such positioning of the stent  46 . Again, gasses may leak by the shoulder  402  into the opposite branched lung passageway BLP′, as indicated by arrow A. Due to collateral flow between lung tissue segments, leakage of air and gasses into one branched lung passageway BLP′ will also cause leakage into the lung tissue segment that seems effectively blocked by the occlusal stent  46  in the other branched lung passageway BLP. Thus, successful blockage of both branched lung passageways BLP by positioning the occlusal stent in the target lung passageways (indicated previously by dashed circles  500 ) is desired to prevent reinflation of the lung tissue segments.  
         [0088]     A variety of occlusal stent designs are provided to reduce the possibility of leakage when positioned within such target lung passageways. For example,  FIGS. 18A-18B ,  19 A- 19 B illustrate additional embodiments of occlusal stents  46  of the present invention. Referring to  FIG. 18A , in this embodiment the stent  46  is again comprised a braid  400  formed into a generally cylindrical shape which extends along a longitudinal axis  404 . The braid  400  is collapsed to form ends or tails which are secured and covered by bushings  401 . The stent  46  also includes a covering  405 .  FIG. 18B  illustrates an end view of the embodiment shown in  FIG. 18A . Referring back to  FIG. 18A , in this embodiment the occlusal stent  46  has square shoulders  402 , which are at an angle which is approximately 90 degrees to the longitudinal axis  404  of the stent  46 , to assist in anchoring the stent  46  within a target area. In addition, the stent  46  has sloping shoulders  402 ′ which are at an angle which is less than 90 degrees, such as approximately 45 degrees, to provide reduced force against the surrounding walls of the lung passageway which in turn reduces remodeling of these walls. The embodiment of the stent  46  illustrated in  FIGS. 18A-18B  has an overall length L along longitudinal axis  404  of approximately 16.5±0.5 mm (0.650±0.020 inches) and a maximum diameter of 9.5±0.1 mm (0.374±0.004 inches). Here, the length of the stent  46  between the square shoulders  402  and the beginning of the sloping shoulders  402 ′ (the contact length CL) is approximately 6.5±0.3 mm (0.264±0.012 inches).  
         [0089]     The embodiment of the stent  46  illustrated in  FIGS. 19A-19B  has an overall length L along longitudinal axis  404  of approximately 16.8±0.5 mm (0.661±0.020 inches) and a maximum diameter of 11.5±0.1 mm (0.453±0.004 inches). Here, the length of the stent  46  between the square set of shoulders  402  and the beginning of the sloping set of shoulders  402 ′ (the contact length CL) is approximately 6.8±0.3 mm (0.268±0.012 inches). In addition, the stent  46  includes a groove  411  along the contact length CL. In this embodiment, the groove  411  has a depth of 0.3 mm and a width of 2.4 mm. Such a groove  411  may assist in preventing migration and extreme tilting of the stent  46  in that the dilated remodeled airway wall will have a section protruding inward toward the stent at the stent&#39;s groove thus locking in the stent at that location with respect to the airway wall.  
         [0090]     In each embodiment of  FIGS. 18A-18B ,  19 A- 19 B, the sloping shoulders  402 ′ reduce the contact length CL thereby reducing the radial force of the stent &#39; 46  against the walls of the lung passageway. In addition, when the stent  46  includes both square shoulders  402  and sloping shoulders  402 ′, the square shoulders  402  may serve to anchor the stent  46  during placement. This is illustrated in  FIG. 20 . Here, the square shoulders  402  may apply greater force to the lung passageway LP thereby anchoring the stent  46  at the proximal end. Thus, the end having the sloping shoulders  402 ′ shall recoil, as indicated by dashed line. Leakage of gasses by the shoulder  402  in the lung passageway LP proximal to the branch is prevented, as indicated by arrow A.  
         [0091]      FIGS. 21A-21B ,  22 A- 22 B illustrate additional embodiments of occlusal stents  46  of the present invention. Referring to  FIG. 21A , in this embodiment the stent  46  is again comprised a braid  400  which extends along a longitudinal axis  404  and is collapsed to form ends or tails which are secured and covered by bushings  401 . The stent  46  also includes a covering  405 .  FIG. 21B  illustrates an end view of the embodiment shown in  FIG. 21A . Referring back to  FIG. 21A , in this embodiment the occlusal stent  46  has two sections having contact lengths disposed at differing diameters. A first contact length CL 1  is disposed at a diameter of 10.9±0.1 mm (0.429±0.004 inches) and a second contact length CL 2  is disposed at a diameter of 5.6±0.1 mm (0.220±0.004 inches). The stent  46  has square shoulders  402  which are at an angle which is approximately 90 degrees to the longitudinal axis  404  of the stent  46  near one end of the stent  46 . The first contact length CL 1  and second contact length CL 2  are separated by sloping shoulders  402 ′ which are at an angle which is less than 90 degrees, such as approximately 45 degrees. And, the stent  46  has additional sloping shoulders  402 ″ which are at an angle which is less than 90 degrees, such as approximately 45 degrees, near the other end of the stent  46 . The embodiment of the stent  46  illustrated in  FIGS. 21A-21B  has an overall length L along longitudinal axis  404  of approximately 17.5±0.2 mm (0.689±0.008 inches) and first and second contact lengths CL 1 , CL 2  of any desirable length. Additionally, the proximal corner where the contact length CL 1  transitions to the shoulder section  402  can include a radially protruding radius or bump to further secure the device at that location of the bronchial wall, as shown later in  FIG. 27   i.    
         [0092]      FIGS. 22A-22B  illustrate a similar embodiment wherein the occlusal stent  46  has two sections having contact lengths disposed at differing diameters. Here, a first contact length CL 1  is disposed at a diameter of 12.0±0.1 mm (0.472±0.004 inches) and a second contact length CL 2  is disposed at a diameter of 5.6±0.1 mm (0.220±0.004 inches). Again, the stent  46  has square shoulders  402  which are at an angle which is approximately 90 degrees to the longitudinal axis  404  of the stent  46  near one end of the stent  46 . The first contact length CL 1  and second contact length CL 2  are separated by sloping shoulders  402 ′ which are at an angle which is less than 90 degrees, such as approximately 45 degrees. And, the stent  46  has additional sloping shoulders  402 ″ which are at an angle which is less than 90 degrees, such as approximately 45 degrees, near the other end of the stent  46 . In this embodiment, the first contact length CL 1  is curved inwardly toward the longitudinal axis  404 .  
         [0093]     Occlusal stents  46  having contact lengths disposed at differing diameters may be particularly suited for positioning within branched lung passageways. Referring to  FIG. 23 , an embodiment of the occlusal stent  46  is shown positioned so that the first contact length CL 1  is disposed within a lung passageway LP and the second contact length CL 2  is positioned within a branched lung passageway BLP. In many instances, the branched lung passageway BLP has a smaller diameter than the lung passageway LP so the multi-diameter shape of the stent  46  is well suited for maintaining a sufficient seal against the varying passageways without overextending the anatomy. In addition, the multi-diameter shape with sloping shoulders  402 ′,  402 ″ may provide increased flexibility for positioning within lung passageways having various curvatures and take-offs. Further, the square shoulders  402  may serve to further anchor the stent  46 . Also, the amount of radial tension before recoil is reduced in the distal section BLP to encourage recoil in the proximal direction since greater radial tension will be in the proximal section which is thus relatively resistant to recoil in the distal direction.  
         [0094]      FIGS. 24A-24B ,  25 A- 25 B illustrate embodiments of occlusal stents  46  having a channel  409  along at least one contact length. A channel  409  is a portion of the contact length that juts inward toward the longitudinal axis  404 . Thus, the channel  409  has a reduced diameter in comparison to the contact length within which it resides.  FIG. 24A  illustrates an occlusal stent  46  similar to the stent  46  of  FIG. 21A , however here the stent  46  includes a channel  409  along the first contact length CL 1 . Similarly,  FIG. 24B  illustrates an end view of the embodiment shown in  FIG. 24A .  FIG. 25A  illustrates an occlusal stent  46  similar to the stent  46  of  FIG. 18A , however here the stent  46  includes a channel  409  along the contact length CL.  FIG. 25B  illustrates an end view of the embodiment shown in  FIG. 25A . When the occlusal stent  46  is positioned within a lung passageway LP, as illustrated in  FIG. 26 , tissue T may grow into the channel  409  as shown. The ingrowth of tissue T may resist excessive linear movement of the stent  46  along the lung passageway LP, anchoring the stent  46  in place. In addition, the channel  409  may increase flexibility of the stent  46  in the region of the channel  409  which may be beneficial for positioning within certain anatomies. A further advantage of the groove is the potential for fluid build up in the groove which will contribute to sealing.  
         [0095]      FIGS. 27A-27N  illustrate side views of additional embodiments having differing configurations or shapes. Generally, as shown, the configurations are symmetrical in relation to the longitudinal axis  404 .  FIG. 27A  shows an embodiment having a groove or waist  410 , a narrower diameter between first shoulders  412  and second shoulders  414 . Such a waist  410  enhances the ability of the stent  46  to resist migration when subjected to the dynamic forces of breathing, sneezing and coughing.  FIG. 27B  shows a similar embodiment having a waist  410 , however in this embodiment the second shoulders  414  are of a smaller diameter than the first shoulders  412 . Likewise, an additional embodiment shown in  FIG. 27C  also has a waist  410 . However, in this embodiment the first shoulders  412  evert at least partially over the bushing  401 . Further,  FIG. 27D  illustrates an embodiment having multiple waists  410 .  
         [0096]     In other embodiments, the occlusal stent  46  does not include any waists. For example,  FIG. 27E  illustrates an embodiment wherein the overall shape is generally oval. This is achieved by having sloping shoulders at both ends of the stent  46 . Likewise,  FIG. 27F  illustrates an embodiment having a design wherein the diameter is uniform between the first shoulders  412  and second shoulders  414 . Such a design may evenly distribute the radial force the stent  46  exerts on the wall of the lung passageway. In addition, the shoulders  412 ,  414  evert at least partially over the bushings  401 . Alternatively, the overall diameter may taper between the first shoulders  412  and second shoulders  414 , as illustrated in an embodiment depicted in  FIG. 27G .  FIG. 27H  illustrates an embodiment having a protuberance  420  between the first shoulders  412  and second shoulders  414 . When the stent  46  of  FIG. 27H  is positioned within a lung passageway, the protuberance  420  applies force to the lung passageway to anchor the stent  46  and resist excessive linear movement of the stent  46  along the lung passageway.  
         [0097]      FIG. 27I  illustrates a stent  46  having a protuberance  420  at the first shoulder  412  and a sloping second shoulder  414 . Again, the protuberance  420  applies force to the lung passageway to anchor the stent  46  and the sloping second shoulder allows any recoiling to be focused toward the anchoring protuberance  420 .  FIG. 27J  illustrates an embodiment similar to that illustrated in  FIG. 27I  with the addition of a groove or waist  410 . Again, the protuberance  420  applies force to the lung passageway to anchor the stent  46  and the waist  410  enhances the ability of the stent  46  to resist migration.  FIG. 27K  illustrates an embodiment similar to that illustrated in  FIG. 21A . In this embodiment, the occlusal stent  46  has two sections having contact lengths CL 1 , CL 2  disposed at differing diameters. The stent  46  has square shoulders  402  which are at an angle which is approximately 90 degrees to the longitudinal axis  404  of the stent  46  near one end of the stent  46 . The first contact length CL 1  and second contact length CL 2  are separated by sloping shoulders  402 ′ which are at an angle which is less than 90 degrees, such as approximately 45 degrees. And, the stent  46  has additional sloping shoulders  402 ″ which are at an angle which is less than 90 degrees, such as approximately 45 degrees, near the other end of the stent  46 . It may be appreciated that the one or both of the sloping shoulders  402 ′,  402 ″ may alternatively be square shoulders  402 . The embodiment illustrated in  FIG. 27L  resembles that of  FIG. 27K  with the addition of a groove or waist  410  along the first contact length CL 1 .  
         [0098]      FIG. 27M  illustrates an embodiment of an occlusal stent  46  having a protuberance  420  and a groove or waist  410  between square shoulders  402 . Again, the protuberance  420  applies force to the lung passageway to anchor the stent  46  and the waist  410  enhances the ability of the stent  46  to resist migration and tilting. Typically, tissue remodeling also forms a pocket in the area of the protuberance so that migration of the stent  46  is also resisted by the protuberance being held in the pocket.  
         [0099]      FIG. 27N  illustrates an embodiment of an occlusal stent having a plurality of waists  410  and a tapering overall shape between a first shoulder  12  and a second shoulder  414 . Thus, any of the features described herein may be combined in any arrangement to form embodiments of occlusal stents  46  of the present invention. Each combination of features may be particularly suitable for a given anatomy or given purpose. In addition, certain combinations of features may be particularly suitable for use when positioning an occlusal stent in a lung passageway nearby another occlusal stent, particularly when the occlusal stents may contact one another.  
         [0100]      FIG. 28  illustrates an embodiment of an occlusal stent  46  of the present invention having a first shoulder  412  which leads into a first contact length CL 1 , as shown. The stent  46  then gradually tapers to a small second shoulder  414 . Similar to stents having contact lengths disposed at differing diameters, the tapered stent of  FIG. 28  may be particularly suited for positioning within branched lung passageways. The first contact length CL 1  may be disposed within a lung passageway LP and the taper extending to the small second shoulder  414  which is positioned within a branched lung passageway BLP. Since, in many instances, the branched lung passageway BLP has a smaller diameter than the lung passageway LP, the tapered shape of the stent  46  is well suited for maintaining a sufficient seal against the varying diameters of the passageways without overextending the anatomy. In addition, the taper may provide increased flexibility for positioning within lung passageways having various curvatures and take-offs. Further, the first contact length CL 1  may serve to further anchor the stent  46 .  FIG. 29  illustrates an embodiment of an occlusal stent  46  of the present invention having a light bulb design. In this embodiment, the stent  46  has a rounded, ball shape  415  which then gradually tapers to a small second shoulder  414  in contrast to the embodiment in  FIG. 28  which has a square profile at its contact area CL 1 . The embodiment of  FIG. 29  can seat in a bifurcation as shown in broken line.  
         [0101]     This stent  46  is also be particularly suited for positioning within branched lung passageways. The ball shape  415  may be disposed within a lung passageway LP and the taper extending to the small second shoulder  414  is positioned within a branched lung passageway BLP. Any tilting or rotating of the ball shape  415  during such placement will not compromise the seal against the lung passageway wall due to the continuously curved surface of the ball shape  415 .  
         [0102]     As mentioned, in some instances the branchings of the lung passageways LP are so close together that positioning of occlusal stents  46  within target areas can provide challenges. Consequently, the occlusal stent  46  may be positioned partially within a branch of a lung passageway. When an occlusal stent  46  has a rigid design along its longitudinal axis  404 , positioning of a portion of an occlusal stent  46  partially within a branch can sometimes cause rotation or tilting of the stent  46  within the lung passageway LP. In some situations, such tilting may increase the risk of leakage. To reduce the possibility of rotation or tilting, a variety of occlusal stent designs are provided having non-rigid longitudinal designs.  
         [0103]     For example,  FIG. 30  illustrates an occlusal stent  46  having a first portion  426  which is positionable within a target lung passageway LP and a second portion  428  which is positionable within a branched lung passageway BLP, the first portion  426  and second portion  428  connected by a flexible portion  430 . In this embodiment, the first portion  426  has a shape which is similar to the embodiment illustrated in  FIG. 12A  and comprises a braid  400  formed into a cylinder which extends along a longitudinal axis  404  between a first shoulder  412  and a second shoulder  414 . The braid  400  is collapsed at one end of the cylinder and secured and covered by a bushing  401 . At the other end of the cylinder, the braid  400  extends through the flexible portion  430  and forms the second portion  428  of the stent  46 . In this embodiment, the second portion  428  has a shape which is similar to the embodiment illustrated in  FIG. 27E  and comprises the braid  400  formed into an oblong shape which extends along a longitudinal axis  404 ′. When the occlusal stent  46  is in its free state, the longitudinal axes  404 ,  404 ′ are alignable. However, flexibility through the flexible portion  430  allows the first portion  426  and second portion  428  to be positioned so that the longitudinal axes  404 ,  404 ′ are at any angle to each other. Therefore, the first portion  426  may be positioned within a target lung passageway LP and a second portion  428  positioned within a branched lung passageway BLP, as illustrated in  FIG. 30 . By allowing each portion  426 ,  428  to maintain different longitudinal axes  404 ,  404 ′, tilting or rotation of the stent  46  is reduced.  
         [0104]     Since branchings of lung passageways typically decrease in diameter, the cross-sectional diameter of the second portion  428  may be less than the first portion  426 .  FIG. 31  illustrates the embodiment of  FIG. 30  outside of the lung passageway. As shown, the second portion  428  may move in relation to the first portion  426 , as indicated by arrows  432 . It may be appreciated that the first and second ends  428  may have any suitable shape. For example, as illustrated in  FIG. 32 , the first and second ends  426 ,  428  may have a more rounded shape. Or, as illustrated in  FIG. 33 , the first and second ends  426 ,  428  may have a funnel shape wherein the braids end in hoops  434  rather than bushings. The ends  426 ,  428  are designed so that the hoops  434  contact the lung passageways to assist in anchoring the occlusal stent  46  in place. It may be appreciated that any occlusal stent features described and/or illustrated herein may be included in the first and second ends  426 ,  428 . Further, it may be appreciated that coverings  405  or some type of flexible material are also provided, typically covering one end of the occlusal stent  46  and wrapping around to the opposite end of the stent  46  leaving an opening for expulsion of air when collapsing the stent  46 . In the embodiment illustrated in  FIG. 33 , a covering  405  may extend over the entire stent  46  leaving one hoop  434  uncovered for expulsion of air when collapsing the stent  46 .  
         [0105]      FIGS. 34A-34B  illustrate another embodiment of an occlusal stent  46  of the present invention which reduces the risk of leakage by rotation or tilting. In this embodiment, the stent  46  is comprised of a braid  400  formed into a round ball-shape between the bushings  401 .  FIG. 34A  shows the stent  46  positioned within a lung passageway LP near a branched lung passageway BLP. Its longitudinal axis  404  is aligned with the lung passageway LP. The portions of the stent  46  contacting the lung passageway LP may be considered the contact lengths CL.  FIG. 34B  shows the stent rotated or tilted within the lung passageway LP so that the longitudinal axis  404  is aligned with the branched lung passageway BLP. However, since the stent  46  has a round ball-shape, the contact lengths CL are maintained as shown. Thus, the possibility of leakage by the stent  46  is reduced.  
         [0106]     Other embodiments of occlusal stents  46  are also provided which assist in maintaining position of the stent  46  in a target area of a lung passageway, resist migration out of the target area, and resist rotation or tilting, to name a few.  FIGS. 35A-35B  illustrate an occlusal device  46  having first portion  426  which is positionable within a target lung passageway LP and a second portion  428  which is positionable within a branched lung passageway BLP. In this embodiment, the first portion  426  has a shape which is similar to the embodiment illustrated in  FIG. 12A  and comprises a braid  400  formed into a cylinder which extends along a longitudinal axis  404  between a first shoulder  412  and a second shoulder  414 . The braid  400  is collapsed and secured at each end by a bushing  401 . The second portion  428  of the stent  46  is comprised of a non-occlusive expandable member, such as a coil  442 . The coil  442  may be comprised of any suitable material, such as a metal or polymer wire or ribbon. The coil  442  may include any number of turns and each turn may have any cross-sectional shape and/or size. In addition, the coil  442  may extend to the first portion  426  or may include a straight section which extends to the first portion  426 , as shown. In some embodiments the second portion  428  is coupled with the first portion  426  and in other embodiments the second portion  428  is simply an extension of the first portion  426 , such as wires of the braid  400  extending from the first section  426 .  
         [0107]     The stent  46  of  FIG. 35A  may be positioned within the lung anatomy as illustrated in  FIG. 35B . Here, the first portion  426  is positioned within the target lung passageway LP and the coil  442  is positioned within the branched lung passageway BLP. The coil  442  may assist in maintaining position of the first portion  426  in a target area of a lung passageway and may help resist migration of the first portion  426  out of the target area. This may be particularly the case when the coil  442  is positioned within or near the junction of the lung passageway LP and the branched lung passageway BLP where the walls are thicker and provide more resistance to tissue remodeling. In addition, if the second portion  428  is sufficiently flexible, positioning of the second portion  428  within the branched lung passageway BLP allows the first portion  426  to maintain alignment within the lung passageway LP, thereby resist rotation or tilting.  
         [0108]      FIGS. 36A-36B  illustrate an occlusal device  46  having first portion  426  which is positionable within a target lung passageway LP and a second portion  428  which is positionable along another portion of the lung passageway. In this embodiment, the first portion  426  has a shape which is similar to the embodiment illustrated in  FIG. 12A  and comprises a braid  400  formed into a cylinder which extends along a longitudinal axis  404  between a first shoulder  412  and a second shoulder  414 . The braid  400  is collapsed and secured at each end by a bushing  401 . The second portion  428  of the stent  46  is comprised of an expandable member, such as a loop  444 . The loop  444  may be comprised of any suitable material, such as a metal or polymer wire or ribbon. The loop  444  may have any cross-sectional shape and/or size. In addition, the loop  444  may be formed at any distance from the first portion  426 . In some embodiments the second portion  428  is coupled with the first portion  426  and in other embodiments the second portion  428  is simply an extension of the first portion  428 , such one or more wires of the braid  400  extending from the first section  426 .  
         [0109]     The stent  46  of  FIG. 36A  may be positioned within the lung anatomy as illustrated in  FIG. 36B . Here, the first portion  426  is positioned within a target area of the lung passageway LP and the loop  444  is positioned proximal to the target area. The loop  444  is typically positioned in a location that is suitable for placement, in this example, proximal to another lung passageway takeoff. The loop  444  may assist in maintaining position of the first portion  426  in the target area of a lung passageway and may help resist migration of the first portion  426  out of the target area. This may be particularly the case when the loop  444  is positioned within or near a junction where the walls are thicker and provide more resistance to tissue remodeling.  
         [0110]      FIGS. 37A-37B  illustrate an occlusal device  46  having first portion  426  which is positionable within a target lung passageway LP and a second portion  428  which is positionable along another portion of the lung passageway. In this embodiment, the first portion  426  has a shape which is similar to the embodiment illustrated in  FIG. 12A  and comprises a braid  400  formed into a cylinder which extends along a longitudinal axis  404  between a first shoulder  412  and a second shoulder  414 . The braid  400  is collapsed and secured at each end by a bushing  401 . The second portion  428  of the stent  46  is comprised of an expandable member, such as a claw  446 . In this embodiment, the claw  446  is comprised of a plurality of hooks  448  which are extendable radially outwardly from the longitudinal axis  404 . The claw  446  may be comprised of any suitable material, such as a metal or polymer wire. In addition, the claw  446  may extend any distance from the first portion  426 . In some embodiments the second portion  428  is coupled with the first portion  426  and in other embodiments the second portion  428  is simply an extension of the first portion  428 , such one or more wires of the braid  400  extending from the first section  426  to form the claw  446 .  
         [0111]     The stent  46  of  FIG. 37A  may be positioned within the lung anatomy as illustrated in  FIG. 37B . Here, the first portion  426  is positioned within a target area of the lung passageway LP and the claw  446  is positioned proximal to the target area. The claw  446  extends radially outwardly so that the hooks  448  contact (and optionally pierce or penetrate) the walls of the lung passageway LP. The claw  446  is typically positioned in a location that is suitable for placement, for example, within or adjacent to the target area. The claw  446  may assist in maintaining position of the first portion  426  in the target area of a lung passageway and may help resist migration of the first portion  426  out of the target area.  
         [0112]     In addition, embodiments of occlusal stents  46  are provided which are designed to reduce any possible potential for inspiratory flow-by. During inspiration, the lung passageways LP expand while air flows into the branches of the lungs. The passageways LP then recoil back to an equilibrium state during expiration. When an occlusal stent  46  is positioned within a lung passageway LP and has relaxed to a maximum expanded state over time, as allowed by tissue remodeling, expansion of the lung passageway LP during inspiration may expand the lung passageway LP beyond the size of the occlusal stent  46 . This may allow air to flow around the stent  46  in a slight gap temporarily formed between the stent  46  and the lung passageway wall.  
         [0113]      FIGS. 38A-38C  illustrate an embodiment of an occlusal stent  46  which expands during inspiration and retracts during expiration to reduce or prevent the possibility of inspiratory flow-by, a condition in which air leaks past the stent during inspiration. Referring to  FIG. 38A , the stent  46  is comprised of a plurality of arms  450  extending from a tip  452  to a wide-mouth  454  forming a funnel shape. The arms  450  may be comprised of any suitable material, such as metal or polymer, and are covered or connected by a covering  405  to obstruct the flow of air or gases therethrough.  FIG. 38A  shows the stent  46  positioned within a lung passageway LP so that the wide-mouth  454  contacts the lung passageway LP. The plurality of arms  450  are biased toward an open configuration so that the wide-mouth  454  seals against the lung passageway LP. Referring now to  FIG. 38B , as the lung passageway LP widens during inspiration (indicated by arrow  456 ), the arms  450  splay further open due to biasing toward the open configuration. This maintains the seal against the lung passageway LP preventing flow-by of air.  FIG. 38C  illustrates a similar embodiment which includes a tail  458  to assist in positioning the stent  46  near branched lung passageways BLP. Here, the tail  458  extends from the tip  452  forming a V-shape. The stent  46  is positionable so that portions of the tail  458  extend into each branched lung passageway BLP at a bifurcation while the wide-mouth  454  seals against the lung passageway LP, as shown. Thus, the tail  458  assists in holding the stent  46  within the target area of the lung passageway LP, preventing migration, rotation and tilting. It may be appreciated that tails  458  may be present on any of the occlusal stents  46  described herein to serve a similar purpose.  
         [0114]      FIGS. 39A-39B  illustrate another embodiment of an occlusal stent  46 . In this embodiment, the occlusal stent  46  is comprised of a braid  400  extending from a tip  452  to a wide-mouth  454  forming a funnel shape. The braid  400  may be comprised of any suitable material, such as metal or polymer, and is covered or connected by a covering  405  to obstruct the flow of air or gases therethrough. In addition, the stent  46  includes a plurality of points or spikes  460  which extend radially outwardly from the stent  46 , typically near the wide-mouth  454 . The spikes  460  are positioned to contact (and optionally pierce or penetrate) the walls of the lung passageway LP to assist in holding the stent  46  in place. Stent  46  may be biased toward an open configuration so that the wide-mouth  454  seals against the lung passageway LP or the stent  46  maybe expanded with the use of a balloon  462  or other expansion device which is positionable within the wide-mouth  454 . Expansion of the balloon  462  within the stent  46  pushes the wide-mouth  454  against the walls of the lung passageway LP, optionally advancing the spikes  460  into the walls. The balloon  462  is then removed and the stent  46  left in place in an open position.  
         [0115]      FIG. 39B  illustrates the stent  46  of  FIG. 39A  positioned within a lung passageway LP so that the wide-mouth  454  contacts the lung passageway LP. The spikes  460  may be angled distally so that inspiration of air (indicated by arrow  456 ) further presses the spikes  460  against, and optionally into, the walls. This may also assist in preventing inspiratory flow-by since the spikes  460  may assist in holding the wide-mouth  454  against the walls during expansion and retraction of the lung passageways LP. Such angling of the spikes  460  may also allow removal of the stent  46  if desired since the stent  46  is approached and removed in the proximal direction. Optionally, the spikes  460  may include barbs which may restrict or prevent removal of the stent  46  in the proximal direction, but may also improve sealing during expansion and retraction of the lung passageways LP. It may be appreciated that spikes  460  may be present on any of the occlusal stents  46  described herein to serve a similar purpose.  
         [0116]      FIGS. 40A-40B  illustrate another embodiment of an occlusal stent  46 . In this embodiment, the occlusal stent  46  has a shape which is similar to the embodiment illustrated in  FIG. 12A  and comprises a braid  400  formed into a cylinder which extends along a longitudinal axis  404  between a first shoulder  412  and a second shoulder  414 . The braid  400  is collapsed at each end and secured and covered by a bushing  401 . In addition, the stent  46  includes one or more wings  470  which extend radially outwardly from the stent  46 , typically near a shoulder such as the first shoulder  412 . The wings  470  are positioned to contact the walls of the lung passageway LP to assist in holding the stent  46  in place.  FIG. 40B  illustrates the stent  46  of  FIG. 40A  positioned within a lung passageway LP so that the wings  470  contact the lung passageway LP. Typically, the wings  470  are angled distally and/or sized to project at least partially into a neighboring branched lung passageway BLP. This may assist in holding the stent  46  in place, particularly during inspiration wherein the wings  470  may apply force to, for example, the junction of the neighboring branched lung passageway BLP resisting movement in the distal direction. This may also assist in preventing inspiratory flow-by since the wings  470  may assist in blocking any flow of air around the stent  46 . It may be appreciated that wings  470  may be present on any of the occlusal stents  46  described herein to serve a similar purpose.  
         [0117]     In some anatomies, the lung passageway LP or other body lumen has a non-symmetrical or irregularly shaped cross-section. Such a lung passageway is illustrated in  FIG. 41A  in a cross-sectional view. Expansion of a rigidly symmetrical occlusal stent  46  within the lung passageway LP, may leave gaps  476  between the stent  46  and the walls of the passageway LP, as shown. Occlusal stents  46  having a non-rigid cross-section may conform to the irregular anatomy, as illustrated in  FIG. 41B , to prevent any gaps  476  from forming. This reduces the possibility of leakage by the occlusal stent  46 . In addition, migration may be reduce due to increased contact with the walls of the lung passageway LP. It may be appreciated that non-rigid cross-sectional construction may be utilized in any of the occlusal stents  46  described herein to serve a similar purpose.  
         [0118]     As mentioned previously, each of the occlusal stent  46  embodiments include a covering  405  to prevent air flow through the stent  46 . Typically, the covering  405  covers one end of the occlusal stent  46  and wraps around the stent  46  to the opposite end of the stent  46  leaving an opening for expulsion of air when collapsing the stent  46 . However, it may be appreciated that the covering  405  may having alternative arrangements, covering various portions of the stent  46 . For example,  FIG. 42  illustrates an embodiment of an occlusal stent  46  having a first covering  405   a , which covers one end of the stent  46 , and a second covering  405   b , which covers the opposite end of the stent  46 . Opening  407  is disposed between the first and second coverings  405   a ,  405   b  so that air is released through the opening  407  when collapsing the stent  46 . In addition, the opening  407  may allow tissue ingrowth into the stent over time to assist in anchoring the stent within the lung passageway. It may be appreciated that the occlusal stents  46  of the present invention may have a variety of other covering  405  arrangements. It should be noted that most of the configurations are described as possessing a braided wire structure, however this is exemplary. The structure can be other forms of scaffolding, such as coil, mesh, weaves, criss-cross patterns, and cut strut patterns.  
         [0119]      FIGS. 43A-43B  illustrate another embodiment of an occlusal stent  46  of the present invention. Here, the stent  46  is comprised of a braid  400  formed into a cylindrical shape which extends along a longitudinal axis  404 .  FIG. 43A  illustrates the occlusal stent  46  in a collapsed configuration for loading within a delivery catheter or device. The stent  46  also includes a spring  413  which is substantially straightened when the stent  46  is collapsed as shown in  FIG. 43A . The spring  413  is attached to the ends of the braid  400 , typically by bonding to or crimping within the attached bushings  401 . The stent  46  also includes a covering  405 . Upon release of the stent  46  from the delivery catheter or device, the spring  413  recoils and draws the bushings  401  toward each other, expanding the stent  46 , as illustrated in  FIG. 43B . In some embodiments, the spring  413  is made from a shape memory alloy wire. The spring  413  is biased to keep the stent  46  expanded and to exert radial force against the walls of a lung passageway when the stent  46  is positioned therein. This added radial force assists in reducing the possibility of occlusal stent migration. In addition, the use of a spring  413  may also be useful to expand occlusal stents  46  having braids  400  which are not made from shape-memory alloys.  
         [0120]      FIGS. 44A-44D  illustrate embodiments of occlusal stents  46  having external anchors  415 . In these embodiments, the anchors  415  are shown extending from the bushings  401  and curving radially outwardly away from longitudinal axis  404 . Such curvature may be at any suitable angle and may be shape-set into the anchor  415  itself. When the occlusal stent  46  is positioned within a lung passageway, one or more anchors  415  may extend to the wall of the lung passageway and apply force to and/or penetrate the wall. Such anchoring assists in reducing migration of the stent  46  within the lung passageway. The anchors  415  may extend from one side of the stent  46 , as illustrated in  FIG. 44A , or from both sides of the stent  46 , as illustrated in  FIG. 44B . The anchors  415  may be added to the stent  46  as separate components or may be comprised of extensions of the braid  400 .  FIGS. 44C-44D  illustrate an embodiment having an internal spring  413 , such as in  FIGS. 43A-43B . Again, the anchors  415  are shown extending from the bushings  401  and curving radially outwardly. Such curvature may be at any suitable angle and may be shape-set into the anchor  415  itself. When the occlusal stent  46  is positioned within a lung passageway, one or more anchors  415  may extend to the wall of the lung passageway and apply force to and/or penetrate the wall. Thus, the anchors may be sharpened to facilitate penetration of the walls. Such anchoring assists in reducing migration of the stent  46  within the lung passageway. The anchors  415  may extend from one side of the stent  46 , as illustrated in  FIG. 44C , or from both sides of the stent  46 , as illustrated in  FIG. 44D . And, as in any of the described occlusal stents  46 , a covering  405  may be present.  
         [0121]     In some embodiments, the occlusal stent  46  includes a viscoelastic material to improve occlusion of the passageway. Such viscoelastic properties are particularly suitable for maintaining occlusion of the lung passageways during inspiratory expansion and expiratory retraction of the passageways. In some embodiments, the stent  46  is filled with a viscoelastic polymer, such as a special constitution and formulation of polyurethane or polyethylene. Alternatively, the stent  46  may be filled with a sponge material or particles of dehydrated sponge material which expand over time due to the natural humidity levels in the lungs. Or, the stent  46  may be filled with autologous mucous. Mucous may have the additional benefit of providing adhesive properties, such as to adhere the stent  46  to the walls of the lung passageway. Mucous can also be disposed on the exterior of the stent  46  to assist in forming a seal with the lung passageway walls. It may be appreciated that such materials may be present instead of or in addition to the coverings  405  described above.  
         [0122]     In some embodiments, the occlusal stent  46  is comprised of tissue-engineered biomaterials, such as a scaffolding seeded with cells. The cells are appropriate for the anatomy within which the stent is to be placed. For example, when positioning within a lung passageway, the stent may be seeded with fibroblasts. In addition, cells from the surrounding environment may grow into the stent, fortifying the occlusal properties of the stent and reducing the possibility of stent migration. The scaffolding may be comprised of a biodegradable polymer so that the scaffolding degrades over time leaving an intact tissue in its place. Such a tissue would be particularly biocompatible and appropriately viscoelastic since the tissue would be essentially part of the surrounding anatomy. Thus, as the lung expands and retracts, the stent would expand and retract accordingly. The stent will act in unison with the airway wall; when the airway moves, the stent maintains intimate contact with the airway wall without dynamic movement occurring at the stent-airway wall interface.  
         [0123]     In addition, occlusal stents  46  of the present invention may include various coatings. Such coatings may include agents such as drugs, antibiotics (such as silver nitrate), tissue growth promoters, or cells, to name a few. Optionally, these coatings may provide controlled delivery over time.  
         [0124]     Although the foregoing invention has been described in some detail by way of illustration and example, for purposes of clarity of understanding, it will be obvious that various alternatives, modifications and equivalents may be used and the above description should not be taken as limiting in scope of the invention which is defined by the appended claims.