Patent Publication Number: US-2023145262-A1

Title: Device with insert plug for occluding the left atrial appendage

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority of U.S. Provisional Application No. 63/277,404 filed Nov. 9, 2021, the entire disclosure of which is hereby incorporated by reference. 
    
    
     TECHNICAL FIELD 
     The disclosure pertains to occlusion devices and more particularly to implantable occlusion devices for occluding the left atrial appendage of a patient, and methods for using such occlusion devices. 
     BACKGROUND 
     Implanted occlusion devices are available for insertion into the left atrial appendage (LAA) of the heart. Such devices are used, for example, to block blood clots from passing out of the heart into the systemic circulation. 
     In general, these devices are delivered to the LAA through a catheter system that enters the venous circulation and approaches the left atrium through the atrial septum between the right and left side of the heart. The catheter is guided through the septum toward the ostium of the left atrial appendage. After acquisition and insertion into the LAA the implanted occlusion device is deployed, and fixed so that it remains in the appendage. Once positioned, the implanted occlusion device is released by the catheter, and the catheter system is removed. Over time, the exposed surface structures of the implanted occlusion device spanning the ostium of the LAA becomes covered with tissue. This process is called endothelization. Of the known occlusion devices and methods, each has certain advantages and disadvantages. There is an ongoing need to provide alternative occlusion devices as well as methods for using the occlusion devices. 
     SUMMARY 
     This disclosure provides design, material, manufacturing method, and use alternatives for occlusion devices. An example occlusion device for implantation in a left atrial appendage includes a proximal hub defining a recess configured to releasably connect with a delivery shaft, a frame connected to the proximal hub and extending radially and then distally from the proximal hub, the frame having a proximal portion, an intermediate portion, and a distal portion, the frame comprising a plurality of struts extending between the proximal portion the distal portion, a membrane coupled to and covering at least the proximal portion of the frame, the membrane comprising a material configured to block a passage of blood clots therethrough, and a plug configured to be received in the recess and remain in the recess after implantation. 
     Alternatively or additionally to the embodiment above, the recess includes internal threads. Alternatively or additionally to any of the embodiments above, the plug includes external threads that mate with the internal threads on the recess. 
     Alternatively or additionally to any of the embodiments above, the recess has a first axial length and the plug has a second axial length, wherein the first axial length is greater than the second axial length. 
     Alternatively or additionally to any of the embodiments above, the plug has a connection element configured to releasably couple with a distal end of the delivery shaft. 
     Alternatively or additionally to any of the embodiments above, the plug is configured to move between a first position at a distal end of the recess during delivery, to a second position at a proximal end of the recess after the delivery shaft is disconnected. 
     Alternatively or additionally to any of the embodiments above, when the plug moves to the second position, the delivery shaft is automatically disconnected. 
     Alternatively or additionally to any of the embodiments above, the connection element is a cavity in a proximal face of the plug. 
     Alternatively or additionally to any of the embodiments above, the connection element is an off-center hole in a proximal face of the plug. 
     Alternatively or additionally to any of the embodiments above, the device further comprises a suture extending through the plug, through the distal end of the recess, the suture configured to extend through the delivery shaft. 
     Alternatively or additionally to any of the embodiments above, the plug includes an expandable material, and a distal region of the plug is fixed within a distal region of the recess. 
     Alternatively or additionally to any of the embodiments above, the plug includes a distal plate configured to engage a distal end of the proximal hub. 
     Alternatively or additionally to any of the embodiments above, the plug includes a plate and spring, with a first end of the spring fixed to the plate and a second end of the spring fixed to a distal end of the recess, wherein the spring is biased to extend the plate to a proximal end of the recess. 
     Another example occlusion device for implantation in a left atrial appendage includes a proximal hub defining a recess, a frame connected to the proximal hub and extending distally therefrom, the frame configured to move between a radially collapsed delivery configuration and a radially expanded configuration for engaging an interior wall of the left atrial appendage, a membrane coupled to and covering at least a proximal portion of the frame, the membrane comprising a material configured to block a passage of blood clots therethrough, and a plug disposed within the recess in the proximal hub and configured to releasably couple with a distal end of a delivery shaft, the plug configured to move between a first position at a distal end of the recess during delivery and a second position at a proximal end of the recess after the delivery shaft is disconnected, the plug configured to remain in the recess after removal of the delivery shaft. 
     An example system for implanting an occlusion device in a left atrial appendage includes a flexible delivery catheter. a delivery shaft extending through the delivery catheter, and an occlusion device comprising a proximal hub defining a recess configured to releasably connect with the delivery catheter, a frame connected to the proximal hub and extending radially and then distally from the proximal hub, the frame having a proximal portion, an intermediate portion, and a distal portion, the frame comprising a plurality of struts extending between the proximal portion the distal portion, a membrane coupled to and covering at least the proximal portion of the frame, the membrane comprising a material configured to block a passage of blood clots therethrough, a plug configured to be received in the recess and remain in the recess after implantation, the plug having a first connection element on a proximal end thereof, wherein the delivery shaft has a second connection element on a distal end thereof, the second connection element configured to releasably engage the first connection element on the plug. 
     Alternatively or additionally to the embodiment above, the distal end of the delivery shaft includes external threading, the recess includes internal threads, and the plug includes external threads, wherein when the second connection element of the delivery shaft engages the first connection element of the plug, the external threading on the plug and delivery catheter defines continuous threading that mates with the internal threading of the recess. 
     Alternatively or additionally to any of the embodiments above, the plug is configured to move between a first position at a distal end of the recess during delivery, to a second position at a proximal end of the recess after the delivery shaft is disconnected, wherein when the plug moves to the second position, the delivery shaft is automatically disconnected. 
     Alternatively or additionally to any of the embodiments above, one of the first and second connection elements is a cavity and the other of the first and second connection elements is a protrusion configured to engage the cavity. 
     Alternatively or additionally to any of the embodiments above, the first connection element is an off-center hole in a proximal face of the plug and the second connection element is an off-center protrusion extending distally from the distal end of the delivery shaft, the off-center hole configured to receive the off-center protrusion. 
     Alternatively or additionally to any of the embodiments above, the system further comprises a suture having two free ends, the suture extending through the plug, through the distal end of the recess, and through the delivery catheter, with the two free ends positioned proximal of a proximal end of the delivery catheter. 
     The above summary of some embodiments, aspects, and/or examples is not intended to describe each embodiment or every implementation of the present disclosure. The figures and the detailed description which follows more particularly exemplify these embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure may be more completely understood in consideration of the following detailed description of various embodiments in connection with the accompanying drawings, in which: 
         FIG.  1    is a perspective proximal view of a prior art occlusion device; 
         FIG.  2    is a perspective proximal view of an example occlusion device according to the present disclosure; 
         FIG.  3    is a cross-sectional view taken along line  3 - 3  of  FIG.  2   ; 
         FIG.  4    shows enlarged region  4  of  FIG.  3   ; 
         FIG.  5 A  is a perspective view of an example delivery shaft and plug; 
         FIG.  5 B  is a close-up view of the distal end of the delivery shaft of  FIG.  5 A ; 
         FIG.  5 C  is a close-up view of the plug of  FIG.  5 A ; 
         FIGS.  6 A- 6 C  are side cross-sectional views of the delivery shaft and plug of  FIG.  5 A  engaged with a portion of the occlusion device shown in  FIG.  4   , at various stages of deployment; 
         FIG.  7    is a perspective close-up view of the proximal hub of the occlusion device of  FIG.  6 C ; 
         FIG.  8    is a perspective view of an alternative plug; 
         FIG.  9 A  is a side cross-sectional view of another example delivery shaft and plug; 
         FIG.  9 B  is a bottom view of the delivery shaft of  FIG.  9 A ; 
         FIG.  9 C  is an enlarged view of the plug of  FIG.  9 A ; 
         FIG.  10 A  is a side cross-sectional view of another example delivery shaft and plug; 
         FIG.  10 B  is a side cross-sectional view of the plug of  FIG.  10 A  in an occlusion device during delivery;  FIG.  11 A  is a side cross-sectional view of another example delivery shaft and plug coupled to an occlusion device during delivery; 
         FIG.  11 B  is a side cross-sectional view of the plug of  FIG.  11 A  after removal of the delivery shaft; 
         FIG.  12    is a side cross-sectional view of an alternative plug disposed in an occlusion device; 
         FIG.  13 A  is a side cross-sectional view of another example delivery shaft and plug coupled to an occlusion device during delivery; and 
         FIG.  13 B  is a side cross-sectional view of the plug of  FIG.  13 A  after removal of the delivery shaft. 
     
    
    
     While aspects of the disclosure are amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit aspects of the disclosure to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure. 
     DETAILED DESCRIPTION 
     For the following defined terms, these definitions shall be applied, unless a different definition is given in the claims or elsewhere in this specification. 
     All numeric values are herein assumed to be modified by the term “about,” whether or not explicitly indicated. The term “about”, in the context of numeric values, generally refers to a range of numbers that one of skill in the art would consider equivalent to the recited value (e.g., having the same function or result). In many instances, the term “about” may include numbers that are rounded to the nearest significant figure. Other uses of the term “about” (e.g., in a context other than numeric values) may be assumed to have their ordinary and customary definition(s), as understood from and consistent with the context of the specification, unless otherwise specified. 
     The recitation of numerical ranges by endpoints includes all numbers within that range, including the endpoints (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5). Although some suitable dimensions, ranges, and/or values pertaining to various components, features and/or specifications are disclosed, one of skill in the art, incited by the present disclosure, would understand desired dimensions, ranges, and/or values may deviate from those expressly disclosed. 
     As used in this specification and the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise. It is to be noted that in order to facilitate understanding, certain features of the disclosure may be described in the singular, even though those features may be plural or recurring within the disclosed embodiment(s). Each instance of the features may include and/or be encompassed by the singular disclosure(s), unless expressly stated to the contrary. For simplicity and clarity purposes, not all elements of the disclosure are necessarily shown in each figure or discussed in detail below. However, it will be understood that the following discussion may apply equally to any and/or all of the components for which there are more than one, unless explicitly stated to the contrary. Additionally, not all instances of some elements or features may be shown in each figure for clarity. 
     Relative terms such as “proximal”, “distal”, “advance”, “withdraw”, variants thereof, and the like, may be generally considered with respect to the positioning, direction, and/or operation of various elements relative to a user/operator/manipulator of the device, wherein “proximal” and “withdraw” indicate or refer to closer to or toward the user and “distal” and “advance” indicate or refer to farther from or away from the user. In some instances, the terms “proximal” and “distal” may be arbitrarily assigned in an effort to facilitate understanding of the disclosure, and such instances will be readily apparent to the skilled artisan. Other relative terms, such as “upstream”, “downstream”, “inflow”, and “outflow” refer to a direction of fluid flow within a lumen, such as a body lumen, a blood vessel, or within a device. 
     The term “extent” may be understood to mean a greatest measurement of a stated or identified dimension, unless the extent or dimension in question is preceded by or identified as a “minimum”, which may be understood to mean a smallest measurement of the stated or identified dimension. For example, “outer extent” may be understood to mean a maximum outer dimension, “radial extent” may be understood to mean a maximum radial dimension, “longitudinal extent” may be understood to mean a maximum longitudinal dimension, etc. Each instance of an “extent” may be different (e.g., axial, longitudinal, lateral, radial, circumferential, etc.) and will be apparent to the skilled person from the context of the individual usage. Generally, an “extent” may be considered a greatest possible dimension measured according to the intended usage, while a “minimum extent” may be considered a smallest possible dimension measured according to the intended usage. In some instances, an “extent” may generally be measured orthogonally within a plane and/or cross-section, but may be, as will be apparent from the particular context, measured differently — such as, but not limited to, angularly, radially, circumferentially (e.g., along an arc), etc. 
     The terms “monolithic” and “unitary” shall generally refer to an element or elements made from or consisting of a single structure or base unit/element. A monolithic and/or unitary element shall exclude structure and/or features made by assembling or otherwise joining multiple discrete elements together. 
     It is noted that references in the specification to “an embodiment”, “some embodiments”, “other embodiments”, etc., indicate that the embodiment(s) described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it would be within the knowledge of one skilled in the art to affect the particular feature, structure, or characteristic in connection with other embodiments, whether or not explicitly described, unless clearly stated to the contrary. That is, the various individual elements described below, even if not explicitly shown in a particular combination, are nevertheless contemplated as being combinable or arrangeable with each other to form other additional embodiments or to complement and/or enrich the described embodiment(s), as would be understood by one of ordinary skill in the art. 
     For the purpose of clarity, certain identifying numerical nomenclature (e.g., first, second, third, fourth, etc.) may be used throughout the description and/or claims to name and/or differentiate between various described and/or claimed features. It is to be understood that the numerical nomenclature is not intended to be limiting and is exemplary only. In some embodiments, alterations of and deviations from previously-used numerical nomenclature may be made in the interest of brevity and clarity. That is, a feature identified as a “first” element may later be referred to as a “second” element, a “third” element, etc. or may be omitted entirely, and/or a different feature may be referred to as the “first” element. The meaning and/or designation in each instance will be apparent to the skilled practitioner. 
     The following description should be read with reference to the drawings, which are not necessarily to scale, wherein similar elements in different drawings are numbered the same. The detailed description and drawings are intended to illustrate but not limit the disclosure. Those skilled in the art will recognize that the various elements described and/or shown may be arranged in various combinations and configurations without departing from the scope of the disclosure. The detailed description and drawings illustrate example embodiments of the disclosure. However, in the interest of clarity and ease of understanding, while every feature and/or element may not be shown in each drawing, the feature(s) and/or element(s) may be understood to be present regardless, unless otherwise specified. 
     There is a continuing need to improve implanted occlusion devices as well as the methods and devices used to deliver them into the left atrial appendage (LAA). In some cases, exposed metal and threads on the proximal end of LAA occlusion devices exposed to the left atrium may become thrombogenic, leading to device-related thrombus (DRT). If DRT is present, patients cannot come off of Warfarin, defeating the purpose of the device. Furthermore, a thrombus formed on the proximal end of the device may break free, possibly causing an ischemic stroke. Reducing DRT is a desired advance in LAA closure devices. 
       FIG.  1    illustrates an example implantable occlusion device  1 , such as that disclosed in U.S. Pat. No. 9,913,652, which is incorporated herein by reference. The occlusion device  1  illustrated in  FIG.  1    is shown in the expanded, deployed configuration. The occlusion device  1  may be delivered in a collapsed, compressed configuration through a catheter. It may be biased into the expanded or deployed configuration by the super-elastic nature of the material used to make the frame  2 . In the deployed configuration, the device, and more specifically, the occlusion membrane  3  disposed over the proximal region of the device, spans the ostium of the LAA. The occlusion device  1  may include retention members associated with the periphery of the occlusion device  1 . In some embodiments, the retention structure includes a series of barbs  4 . The barbs  4  may be configured to penetrate tissue and retain the occlusion device  1  in the interior of the LAA during implantation. The occlusion device in  FIG.  1    is seen from the proximal end in perspective. In situ, the occlusion membrane  3  completely covers the surface exposed to the interior of the heart chamber. An internally threaded connector  5  releasably couples the device to a threaded delivery shaft. In some cases, the exposed threading and recess of the connector  5  may contribute to DRT. 
       FIGS.  2 - 4    illustrate an occlusion device  100  with a plug  150  disposed in the recess within the proximal hub  124 , flush with the proximal face of the device, thereby reducing thrombus risk. The structure of the frame  120  with barbs  140 , and the occlusion membrane  130 , as shown in  FIG.  2   , may be similar to the occlusion device  1  described in U.S. Pat. No. 9,913,652. The occlusion membrane  130  may cover the proximal end of the frame  120  and extend partially along sides of the frame  120 . When the device is in position within an LAA, the occlusion membrane  130  spans the ostium and intercepts clots or mediates blood flowing in and out of the LAA. In some embodiments, the occlusion membrane  130  may be a filter member that blocks the passage of blood clots, but is permeable to blood flow there through. Alternatively, the occlusion membrane  130  may be of a material impermeable to blood flow. The occlusion membrane  130  may be fabricated from any suitable biocompatible materials. These materials include, but are not limited to, for example, ePTFE (e.g. Gore-Tex), polyester (e.g. Dacron®), PTFE (e.g. Teflon®), silicone, urethane, metal fibers, and other biocompatible polymers. 
     As shown in the cross-sectional view in  FIG.  3   , the occlusion device  100  may have a frame  120  extending radially and the distally from a proximal hub  124 . The frame  120  may include a proximal portion, and intermediate portion, and a distal portion. The frame  120  may be formed from a plurality of struts  122  joined at the proximal hub  124  and a distal hub  126 . A plurality of hooks or barbs  140  may extend radially outward from some of the struts  122 . The barbs  140  may serve to secure the device in the LAA. As shown in the close-up view in  FIG.  4   , the plurality of struts  122  may be joined at a proximal hub  124 . The proximal hub  124  may include an inner member  125  defining a recess  127  with internal threading  128 . The internal threading  128  may extend along the entire axial length of the recess  127 . The plug  150  is disposed within the recess  127 . 
       FIG.  5 A  illustrates a delivery shaft  160  configured to engage the occlusion device  100  during delivery through a catheter (not shown). The delivery shaft  160  may have a flared skirt  162  and a threaded distal end  164 . A plug  150  may be releasably coupled with the threaded distal end  164 .  FIG.  5 B  is a close-up of the threaded distal end  164  of the delivery shaft  160 , uncoupled from the plug  150 . The plug  150  may have a first connection element configured to releasably couple with a second connection element on the distal end of the delivery shaft  160 . In the example shown in  FIG.  5 B , the threaded distal end  164  may include a distally extending protrusion  166 .  FIG.  5 C  shows the plug  150  of  FIG.  5 A  uncoupled from the delivery shaft  160 . The proximal face  156  plug  150  may have a cavity  154  configured to receive the protrusion  166  in the threaded distal end  164  of the delivery shaft  160 . the plug  150  may have external threading  152  configured to mate with the internal threading  128  in the recess of the proximal hub  124 . The engagement between the protrusion  166  and cavity  154  may be similar to a screw driver and screw; tight enough to prevent the protrusion  166  from twisting out of the cavity  154  but loose enough to allow the protrusion  166  to be removed from the cavity  154  when the two parts are not threaded into the recess  127 . In the embodiment shown in  FIGS.  5 A- 5 C , the threaded distal end  164  and the plug  150  have external threading that forms a continuous thread when the plug  150  is connected to the threaded distal end  164  of the delivery shaft  160 . This continuous thread allows the plug  150  and threaded distal end  164  to be threaded into and out of the recess  127  as a single unit. 
     In  FIG.  6 A , the delivery shaft  160  and coupled plug  150  of  FIG.  5 A  is shown threaded into the recess  127  within the proximal hub  124  of the occlusion device  100  of  FIGS.  2 - 4   . The flared skirt  162  may be configured to engage the proximal hub  124 . The threaded distal end  164  may be provided on an inner wire  168  extending proximally through the delivery shaft  160 . In some embodiments, the inner wire  168  may be slidable relative to the delivery shaft  160 . In other embodiments, the threaded distal end  164  may be provided on the distal end of the delivery shaft  160 . As illustrated, the threaded distal end  164  and external threading  152  on the plug  150  are threadingly engaged with the internal threading  128  of the recess  127  in the proximal hub  124 . 
     The recess  127  may have a first axial length and the plug  150  may have a second axial length, with the first axial length being greater than the second axial length. This allows the plug  150  to move along the length of the recess  127  from a first position at the distal end  121  of the recess  127  during delivery, as shown in  FIG.  6 A , to a second position at the proximal end  123  of the recess  127  after the delivery shaft  160  has been disconnected, as shown in  FIG.  6 C . In some embodiments, the first axial length of the recess  127  may be at least  1 . 5  times the second axial length of the plug  150 . In other embodiments, the first axial length may be twice the second axial length. 
     The protrusion  166  on the threaded distal end  164  of the delivery shaft  160  is disposed within the cavity  154  of the plug  150 . This engagement causes the plug  150  to rotate with the delivery shaft  160 , and to move proximally through the recess  127  as the delivery shaft  160  is rotated to withdraw the threaded distal end  164  proximally from the proximal hub  124 . As shown in  FIG.  6 B , the delivery shaft  160  and threaded distal end  164  have been withdrawn proximally until the plug  150  is adjacent the proximal end  123  of the recess  127 . As the plug  150  is coupled to the threaded distal end  164  of the delivery shaft  160  only by the protrusion  166  of the threaded distal end  164  sitting within the cavity  154  of the plug  150 , once the threading on the threaded distal end  164  no longer engages the internal threading  128  in the recess  127 , the protrusion  166  automatically slides out of the cavity  154 , and the delivery shaft  160  is uncoupled from the plug  150 . The plug  150  remains within the recess  127 , flush with the proximal end  123  of the recess  127 , as shown in  FIG.  6 C . The plug  150  covers the internal threading  128  and fills the recess  127 , thereby reducing thrombus formation.  FIG.  7    shows the plug  150  seated within the recess  127 , with the proximal face  156  of the plug  150  flush with the proximal end of the proximal hub  124 . 
     In another embodiment, the engagement structures of the plug  150  and the threaded distal end  164  of the delivery shaft  160  may be reversed. As shown in  FIG.  8   , the plug  250  may be externally threaded like the plug  150  described above, but may have a protrusion  254  which may be configured to engage a cavity in the distal end of the delivery shaft  160 . 
     In another embodiment, instead of the cavity and protrusion coupling the plug  150  and delivery shaft  160  as discussed above, the connection element on the plug  350  may be an off-center axially extending hole  355  in the proximal face of the plug, configured to receive an off-center protrusion such as an elongated pin  366  extending distally and off-center from the threaded distal end  364  of the delivery shaft  360 , as shown in  FIG.  9 A .  FIG.  9 B  illustrates a distal end view of the threaded distal end  364  of the delivery shaft  360 , showing the off-center position of the elongated pin  366 .  FIG.  9 C  illustrates a cross-sectional view of the plug  350  showing the off-center position of the axially extending hole  355  configured to receive the elongated pin  366 . The off-center position of the hole  355  and elongated pin  366  provides the torque to rotate the plug  350  with the delivery shaft  360 . The remaining structure of the plug  350  and delivery shaft  360  may be the same as the plug  150  and delivery shaft  160  described above. As with the above-described plugs  150 ,  150 , the plug  350  covers the internal threading  128  and fills the recess  127  of the proximal hub on the occlusion device, thereby reducing thrombus formation. 
     Similar to the embodiment shown in  FIGS.  6 A- 6 C , in addition to a protrusion  466  on the threaded distal end  464  of the delivery shaft  460  being disposed within the cavity  454  of the plug  450 , the plug  450  may be coupled to the delivery shaft  460  by a suture  470 , as shown in  FIGS.  10 A and  10 B .  FIG.  10 A  shows the suture  470  threaded through a lumen in the delivery shaft  460  and threaded distal end  464 , through two separate holes in the plug  450  and back through the delivery shaft  460 . The suture has two free ends and both free ends of the suture  470  may be disposed proximal of the delivery shaft  460 . In some embodiments, the suture  470  may be threaded around a transverse pin  429  extending across the distal end of the recess  427  in the proximal hub  424 , as shown in  FIG.  10 B . As the plug  450  is withdrawn to the proximal end of the recess  427 , the rotation of the plug  450  may twist the suture  470  between the distal end of the plug  450  and the transverse pin  429 , as shown in  FIG.  10 B . When the delivery shaft  460  rotates out of the recess  427  and releases the plug  450 , the suture maintains a connection between the threaded distal end  464  of the delivery shaft  460  and the plug  450 . If the position of the occlusion device needs to be adjusted, the suture  470  may help guide the protrusion  466  of the threaded distal end  464  of the delivery shaft  460  back in to the cavity  454  of the plug  450 . The plug  450  may then be screwed back to the distal end of the recess  427  at which point the threaded distal end  464  of the delivery shaft  460  is also disposed within the recess  427  of the proximal hub  424 . The position of the occlusion device can then be adjusted, followed by removal of the delivery shaft  460 . Once the delivery shaft  460  is removed from the plug  450 , one end of the suture  470  may be pulled, unthreading the suture from the delivery shaft  460  and the plug  450 . As with the above-described plug  150 , the plug  450  covers the threading and fills the recess  427  of the proximal hub on the occlusion device, thereby reducing thrombus formation. 
     Instead of a threaded plug, an expandable plug  550  may be positioned within the proximal hub  524 , compressed by the threaded distal end  564  of the delivery shaft  560 , as shown in  FIG.  11 A . When the occlusion device is in the desired position, the delivery shaft  560  may be unscrewed from the proximal hub  524 , allowing the expandable plug  550  to expand and fill the entire recess  527  in the proximal hub  524 , as shown in  FIG.  11 B . The expandable plug  550  thereby reduces thrombus formation. The expandable plug  550  may be self-expandable in the absence of the compressive force of the threaded distal end  564  of the delivery shaft  560 . For example, the expandable plug  550  may be made of expandable material such as foam, polymer, or silicone. In some examples, the expandable plug  550  may be fixed within the distal region of the recess  527  in the proximal hub  524  with at least one transverse pin  529  extending through opposite sidewalls of the proximal hub  524  and through the expandable plug  550 , as shown in  FIG.  11 B . In some examples, the transverse pin  529  may include two separate pins extending into the expandable plug  550  from opposite sides through the proximal hub  524 . In other embodiments, the distal end of the expandable plug  550  may be fixed to the distal end of the recess  527 , such as with adhesive. 
     In a further embodiment, an expandable plug  650 , similar to the expandable plug  550  described above, may include a distal plate  657  extending transverse across the recess  627  of the proximal hub  624  to engage a distal end of the proximal hub  624 , as shown in  FIG.  12   . The distal plate  657  may prevent the expandable plug  650  from being removed proximally from the recess  627 . The expandable plug  650  and the distal plate  657  may be a single monolithic piece, or the distal plate  657  may be made of a different material and fixed to the distal end of the expandable plug  650 . As shown in  FIG.  12   , after removal of the delivery shaft, the expandable plug  650  has expanded to completely fill the recess in the proximal hub  624  of the occlusion device, thereby reducing thrombus formation. Alternatively, in another embodiment, the plug takes the form of a spring-loaded plate  757 , as shown in  FIGS.  13 A and  13 B . During delivery, the threaded distal end  764  of the delivery shaft  760  may be screwed into the internally threaded recess  727 , abutting the plate  757  and compressing the spring  750 . The spring  750  may have a first end fixed to the plate  757  and a second end fixed to the distal end of the recess  727  of the proximal hub  724 . See  FIG.  13 A . The distal end of the threaded distal end  664  may be flat to engage a flat proximal surface of the plate  757 . The spring  750  is biased such that as the threaded distal end  764  of the delivery shaft  760  is unscrewed and removed from the proximal hub  724  of the occlusion device, the spring  750  expands, extending the plate  757  to the proximal end of the recess  727 , as shown in  FIG.  13 B . With the proximal surface of the plate  757  flush with the proximal end of the proximal hub  724 , as shown in  FIG.  13 B , the plate  757  covers the recess  727  and its internal threading, thereby reducing thrombus formation. 
     While the protrusions  166 ,  254 ,  466  and their mating cavities  154 ,  454  are illustrated in the figures as being longitudinal protrusions and slots/grooves such as those seen on a conventional flat head screwdriver and screw, it will be understood that the geometry of the mating elements may be any that achieves the mating structure of the protrusion fitting within the cavity and allowing the two associated parts to rotate together and then separate as discussed above. Some example geometries for alternative protrusions and associated cavities include the following geometries of drill and driver bits: square, hex, pentagon, Phillips, Torx®, security Torx®, Tri-Wing®, spline, spanner, Pozidriv®, hex socket/Allen®, square recess, clutch, Mortorq®, Frearson, supadriv, Polydrive®, double square, Bristol, Torqset®, one-way, pentalobe, TP3, TTAP, and triangle/TA. 
     The plug  150 ,  250 ,  350 ,  450 ,  550 ,  650 ,  757  may be made from and/or coated with a polymer that resists thrombus, such as polytetrafluoroethylene (PTFE), or may be metallic, with or without a coating or surface texture that is advantageous for healing and biocompatibility. The coating may be an anti-thrombogenic coating. In some embodiments, the plug  150 ,  250 ,  350 ,  450 ,  550 ,  650 ,  757  may be made of or coated with a drug-eluting composition, for example an anti-thrombogenic drug composition. 
     To deploy the occlusion device  100  in an LAA, the occlusion device  100  is coupled to a delivery shaft  160 , such as by the threaded distal end  164  to a plug  150  within a recess  127  in the proximal hub  124  of the occlusion device  100 . The occlusion device may be radially collapsed within a flexible delivery catheter that is then percutaneously moved through the blood vessel to the desired location. When the end of the delivery catheter is adjacent the desired location, the device is deployed, allowing the frame  120  to radially expand to its relaxed size and shape configured for engaging an interior wall of the LAA, as depicted in  FIG.  2   . When the occlusion device  100  is properly positioned and fully deployed, it is untethered or released from the delivery shaft  160  by uncoupling the delivery shaft  160  from the plug  150 , leaving the plug  150  flush with the proximal end of the proximal hub  124 . The plug  150  fills the recess  127  in the proximal hub  124  and covers any internal threading in the recess, thereby reducing thrombus formation at the proximal hub  124 . It will be understood that the above-described method of implanting an occlusion device applies equally to the other example plugs  250 ,  350 ,  450 ,  550 ,  650 ,  750 . 
     The materials that can be used for the various components of the occlusion device  100 , delivery shaft  160 , and plug  150  (and/or other systems or components disclosed herein) and the various elements thereof disclosed herein may include those commonly associated with occlusion devices. For simplicity purposes, the following discussion refers to the occlusion device  100 , delivery shaft  160 , and plug  150  (and variations, systems or components disclosed herein). However, this is not intended to limit the devices and methods described herein, as the discussion may be applied to other elements, members, components, or devices disclosed herein. 
     In some embodiments, the occlusion device  100 , delivery shaft  160 , and plug  150  (and variations, systems or components thereof disclosed herein) may be made from a metal, metal alloy, ceramics, zirconia, polymer (some examples of which are disclosed below), a metal-polymer composite, combinations thereof, and the like, or other suitable material. Some examples of suitable metals and metal alloys include stainless steel, such as 444V, 444L, and 314LV stainless steel; mild steel; nickel-titanium alloy such as linear-elastic and/or super-elastic nitinol; cobalt chromium alloys, titanium and its alloys, alumina, metals with diamond-like coatings (DLC) or titanium nitride coatings, other nickel alloys such as nickel-chromium-molybdenum alloys (e.g., UNS: N06625 such as INCONEL® 625, UNS: N06022 such as HASTELLOY® C-22®, UNS: N10276 such as HASTELLOY® C276®, other HASTELLOY® alloys, and the like), nickel-copper alloys (e.g., UNS: N04400 such as MONEL® 400, NICKELVAC® 400, NICORROS® 400, and the like), nickel-cobalt-chromium-molybdenum alloys (e.g., UNS: R44035 such as MP35-N® and the like), nickel-molybdenum alloys (e.g., UNS: N10665 such as HASTELLOY® ALLOY B2®), other nickel-chromium alloys, other nickel-molybdenum alloys, other nickel-cobalt alloys, other nickel-iron alloys, other nickel-copper alloys, other nickel-tungsten or tungsten alloys, and the like; cobalt-chromium alloys; cobalt-chromium-molybdenum alloys (e.g., UNS: R44003 such as ELGILOY®, PHYNOX®, and the like); platinum enriched stainless steel; titanium; platinum; palladium; gold; combinations thereof; and the like; or any other suitable material. 
     As alluded to herein, within the family of commercially available nickel-titanium or nitinol alloys, is a category designated “linear elastic” or “non-super-elastic” which, although may be similar in chemistry to conventional shape memory and super-elastic varieties, may exhibit distinct and useful mechanical properties. Linear elastic and/or non-super-elastic nitinol may be distinguished from super-elastic nitinol in that the linear elastic and/or non-super-elastic nitinol does not display a substantial “super-elastic plateau” or “flag region” in its stress/strain curve like super-elastic nitinol does. Instead, in the linear elastic and/or non-super-elastic nitinol, as recoverable strain increases, the stress continues to increase in a substantially linear, or a somewhat, but not necessarily entirely linear relationship until plastic deformation begins or at least in a relationship that is more linear than the super-elastic plateau and/or flag region that may be seen with super-elastic nitinol. Thus, for the purposes of this disclosure linear elastic and/or non-super-elastic nitinol may also be termed “substantially” linear elastic and/or non-super-elastic nitinol. 
     In some cases, linear elastic and/or non-super-elastic nitinol may also be distinguishable from super-elastic nitinol in that linear elastic and/or non-super-elastic nitinol may accept up to about 2-5% strain while remaining substantially elastic (e.g., before plastically deforming) whereas super-elastic nitinol may accept up to about 8% strain before plastically deforming. Both of these materials can be distinguished from other linear elastic materials such as stainless steel (that can also be distinguished based on its composition), which may accept only about 0.2 to 0.44 percent strain before plastically deforming. 
     In some embodiments, the linear elastic and/or non-super-elastic nickel-titanium alloy is an alloy that does not show any martensite/austenite phase changes that are detectable by differential scanning calorimetry (DSC) and dynamic metal thermal analysis (DMTA) analysis over a large temperature range. For example, in some embodiments, there may be no martensite/austenite phase changes detectable by DSC and DMTA analysis in the range of about −60 degrees Celsius (° C.) to about 120° C. in the linear elastic and/or non-super-elastic nickel-titanium alloy. The mechanical bending properties of such material may therefore be generally inert to the effect of temperature over this broad range of temperature. In some embodiments, the mechanical bending properties of the linear elastic and/or non-super-elastic nickel-titanium alloy at ambient or room temperature are substantially the same as the mechanical properties at body temperature, for example, in that they do not display a super-elastic plateau and/or flag region. For example, across a broad temperature range, the linear elastic and/or non-super-elastic nickel-titanium alloy maintains its linear elastic and/or non-super-elastic characteristics and/or properties. 
     In some embodiments, the linear elastic and/or non-super-elastic nickel-titanium alloy may be in the range of about 50 to about 60 weight percent nickel, with the remainder being essentially titanium. In some embodiments, the composition is in the range of about 54 to about 57 weight percent nickel. One example of a suitable nickel-titanium alloy is FHP-NT alloy commercially available from Furukawa Techno Material Co. of Kanagawa, Japan. Other suitable materials may include ULTANIUM™ (available from Neo-Metrics) and GUM METAL™ (available from Toyota). In some other embodiments, a super-elastic alloy, for example a super-elastic nitinol can be used to achieve desired properties. 
     In at least some embodiments, portions or all of the occlusion device  100 , delivery shaft  160 , and plug  150  (and variations, systems or components thereof disclosed herein) may also be doped with, made of, or otherwise include a radiopaque material. Radiopaque materials are understood to be materials capable of producing a relatively bright image on a fluoroscopy screen or another imaging technique during a medical procedure. This relatively bright image aids a user in determining the location of the occlusion device  100 , delivery shaft  160 , and plug  150  (and variations, systems or components thereof disclosed herein). Some examples of radiopaque materials can include, but are not limited to, gold, platinum, palladium, tantalum, tungsten alloy, polymer material loaded with a radiopaque filler, and the like. Additionally, other radiopaque marker bands and/or coils may also be incorporated into the design of the occlusion device  100 , delivery shaft  160 , and plug  150  (and variations, systems or components thereof disclosed herein) to achieve the same result. 
     In some embodiments, the occlusion device  100 , delivery shaft  160 , and plug  150  (and variations, systems or components thereof disclosed herein) and/or portions thereof, may be made from or include a polymer or other suitable material. Some examples of suitable polymers may include polytetrafluoroethylene (PTFE), ethylene tetrafluoroethylene (ETFE), fluorinated ethylene propylene (FEP), polyoxymethylene (POM, for example, DELRIN® available from DuPont), polyether block ester, polyurethane (for example, Polyurethane 85A), polypropylene (PP), polyvinylchloride (PVC), polyether-ester (for example, ARNITEL® available from DSM Engineering Plastics), ether or ester based copolymers (for example, butylene/poly(alkylene ether) phthalate and/or other polyester elastomers such as HYTREL® available from DuPont), polyamide (for example, DURETHAN® available from Bayer or CRISTAMID® available from Elf Atochem), elastomeric polyamides, block polyamide/ethers, polyether block amide (PEBA, for example available under the trade name PEBAX®), ethylene vinyl acetate copolymers (EVA), silicones, polyethylene (PE), Marlex® high-density polyethylene, Marlex® low-density polyethylene, linear low density polyethylene (for example REXELL®), polyester, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polytrimethylene terephthalate, polyethylene naphthalate (PEN), polyetheretherketone (PEEK), polyimide (PI), polyetherimide (PEI), polyphenylene sulfide (PPS), polyphenylene oxide (PPO), poly paraphenylene terephthalamide (for example, KEVLAR®), polysulfone, nylon, nylon-12 (such as GRILAMID® available from EMS American Grilon), perfluoro(propyl vinyl ether) (PFA), ethylene vinyl alcohol, polyolefin, polystyrene, epoxy, polyvinylidene chloride (PVdC), poly(styrene-b-isobutylene-b-styrene) (for example, SIBS and/or SIBS  50 A), polycarbonates, ionomers, polyurethane silicone copolymers (for example, Elast-Eon® from AorTech Biomaterials or ChronoSil® from AdvanSource Biomaterials), biocompatible polymers, other suitable materials, or mixtures, combinations, copolymers thereof, polymer/metal composites, and the like. In some embodiments, the sheath can be blended with a liquid crystal polymer (LCP). For example, the mixture can contain up to about 6 percent LCP. 
     In some embodiments, the occlusion device  100  and plug  150  (and variations, systems or components thereof disclosed herein) may include and/or be treated with a suitable therapeutic agent. Some examples of suitable therapeutic agents may include anti-thrombogenic agents such as heparin, heparin derivatives, urokinase, and PPack (dextrophenylalanine proline arginine chloromethyl ketone). 
     It should be understood that this disclosure is, in many respects, only illustrative. Changes may be made in details, particularly in matters of shape, size, and arrangement of steps without exceeding the scope of the disclosure. This may include, to the extent that it is appropriate, the use of any of the features of one example embodiment being used in other embodiments. The disclosure&#39;s scope is, of course, defined in the language in which the appended claims are expressed.