Patent Publication Number: US-2013237908-A1

Title: Sponge-like left atrial occlusion device and related methods of use

Description:
TECHNICAL FIELD 
     This disclosure relates to devices and methods for occluding a body lumen or cavity. More particularly, the technologies disclosed herein relate to, devices, and methods for achieving atrial appendage occlusion via expandable sponge-like material. 
     BACKGROUND 
     Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia affecting over 5.5 million people worldwide. AF is the irregular, chaotic beating of the upper chambers of the heart. Electrical impulses discharge so rapidly that the atrial muscle quivers or fibrillates. Episodes of AF may last a few minutes or several days. The most serious consequence of AF is ischemic stroke. It has been estimated that up to 20% of all strokes are related to AF. Most AF patients, regardless of the severity of their symptoms or frequency of episodes, require treatment to reduce the risk of stroke. 
     In patients with AF, blood tends to pool and form clots in an area of the heart called the left atrial appendage (LAA). The LAA is a pouch-like extension located in the upper left chamber of the heart. A blood clot that breaks loose from this area may migrate through the blood vessels and eventually occlude a smaller vessel in the brain or heart resulting in a stroke or heart attack. Clinical studies show that the majority of blood clots in patients with AF originated in the LAA. 
     One treatment mechanism for atrial fibrillation addresses the source of dangerous blood clots by occluding the left atrium appendage. Such treatments may include medication, surgery, or minimally invasive techniques. Surgical procedures may include trans-catheter closure of the LAA, which is challenging due to the highly variable and complex nature of human LAAs. Other closure methods include epicardial LAA ligation and surgical closure. Another approach employs metallic cages or fabric designs that occlude the ostium of the LAA when deployed. These devices are generally delivered to the treatment site via a catheter system. 
     There remains a need for improvement and/or alternatives in providing systems and methods for occlusion of left atrial appendage. 
     SUMMARY 
     The disclosure is directed to several alternative designs, materials, and methods of manufacturing medical device structures and assemblies. 
     Accordingly, some embodiments pertain to a medical device for occluding left atrial appendage of a human heart, including an occlusion device comprising an expandable sponge-like component having a proximal end and a distal end. The expandable sponge-like component of the medical device is configured to transition between a compressed configuration and an expanded configuration such that the expanded configuration is configured to conform to at least the ostium of the LAA, which can prevent clots from exiting the LAA to the left atrium of the heart. The sponge-like component may have any desired geometry such as, but not limited to, cylindrical or spherical shape. Further, the component may include a biodegradable biomaterial having a porous structure, and may also be impregnated with a therapeutic agent that is released when the occlusion device is deployed or which releases slowly over time after the occlusion device is deployed. Some embodiments may also contain a coating. 
     Some embodiments pertain to an occlusion system for left atrial appendage of a human heart, including a catheter with a lumen extending along the central catheter axis. The catheter has a proximal end and a distal end. The system further includes an occlusion device comprising an expandable sponge-like component that may include some or all of the features described above. The system may further include a push wire disposed within the lumen, the distal end of the push wire is in contact with the proximal end of the sponge-like component and is operable to advance the sponge-like component out of the distal end of the catheter. In addition, the system may also include a connecting member configured to detachably connect the distal end of the push wire with the proximal end of the sponge-like component. To this end, the connecting member may include, for example, a male thread at the proximal end of the push wire and a corresponding female thread attached to the proximal end of the sponge-like component. Here, the female thread may include a nut. 
     Some embodiments also pertain to a method for occluding the Left Atrial Appendage (LLA) of a human heart. The method may include advancing a catheter via tras-septal crossing to a position within the LAA. The catheter has a proximal end, a distal end, a lumen extending therebetween, and a medical device slidingly disposed within the lumen. Here, the medical device includes an occlusion device comprising an expandable sponge-like component configured to transition between a compressed configuration and an expanded configuration, wherein the expanded configuration is configured to conform to at least the entrance to the LAA, sufficient to prevent blood flow within the heart from entering the LAA. The occlusion device may be advanced out of the lumen of the catheter resulting in expansion of the medical device from the compressed configuration to conform to the LAA. Here, advancing the medical device out of the lumen of the catheter includes advancing the medical device using a push wire. Further, the push wire is disposed within the lumen of the catheter such that the distal end of the push wire is connected to the proximal end of the sponge-like component. In addition, the push wire may include a connecting member for providing a detachable connection between the push wire and the sponge-like component. The method may further include retracting the catheter along with the push wire once the device is deployed. 
     The summary of some example embodiments in not intended to describe each disclosed embodiment or every implementation of the disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present 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  illustrates a perspective view of a medical device for occluding left atrial appendage of a human heart in accordance with the present disclosure. 
         FIG. 2  is a schematic view of the medical device of  FIG. 1  disposed within a catheter according to one embodiment of the present disclosure. 
         FIGS. 3-5  illustrate an exemplary method of using the medical device of  FIG. 1  according to an embodiment of the present disclosure. 
     
    
    
     While embodiments of the present 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 present 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 the specification. 
     All numeric values are herein assumed to be modified by the term “about,” whether or not explicitly indicated. The term “about” generally refers to a range of numbers that one of skill in the art would consider equivalent to the recited value (i.e., having the same function or result). In many instances, the term “about” may be indicative as including numbers that are rounded to the nearest significant FIG. 
     The recitation of numerical ranges by endpoints includes all numbers within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5). 
     Although some suitable dimension 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 many 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. 
     The following detailed description should be read with reference to the drawings in which similar elements in different drawings are numbered the same. The detailed description and the drawings, which are not necessarily to scale, depict illustrative embodiments and are not intended to limit the scope of the disclosure. The illustrative embodiments depicted are intended only as exemplary. Selected features of any illustrative embodiment may be incorporated into an additional embodiment unless clearly stated to the contrary. 
     Embodiments of the present disclosure describe a medical device adapted to occlude the left atrial appendage (LAA) of a human heart. In general, the medical device may be an occlusion device comprising a compressible sponge-like component configured to transition between a compressed configuration and an expanded configuration. The expanded configuration of the sponge-like component may be configured to conform to the varying size and shape of the LAA. 
     While the devices and methods described herein are discussed relative to left atrial appendage occlusion, it is contemplated that the devices and methods may be used in other applications where body lumen occlusion is desired. 
     In some instances, it may be desirable to employ trans-septal crossing for deployment of the medical device to occlude the LAA. It may be, however, understood that other routes may also be employed to deploy the medical device within the LAA cavity. In addition, positioning the device within the LAA cavity may employ a delivery device including, but not limited to, a catheter. 
       FIG. 1  illustrates an embodiment of a medical device  100  for occluding a left atrial appendage (LAA) of a human heart in accordance with the present disclosure. The medical device  100  includes an expandable sponge-like component  102  having a proximal end  104  and a distal end  106 . It will be understood that “proximal” and “distal”, as used in this disclosure, refers to positions or directions nearer to or farther from the user, respectively. 
     In the illustrated embodiment, sponge-like component  102  is cylindrical, which may also contemplate other shapes such as circular, rectangular, conical, spherical, and the like. Further, sponge-like component may have a dimension equal to or greater than the dimensions of the LAA cavity such as it may occlude the LAA. In general, the diameter of the sponge-like component  102  maybe greater than the diameter of the LAA. In addition, the configuration of the component  102  may be uniform throughout its length or it may vary based on the cavity dimensions of the LAA. The sponge-like component has a generally solid cross-section 
     Sponge-like component  102  may include a close-cell sponge or an open-cell sponge. The open-cell sponge-like component  102  may allow the blood flow within the heart to enter the LAA without permitting a clot formation to exit the LAA, while the close-cell sponge-like component  102  may prevent the blood flow within the heart from entering the LAA. Sponge-like component  102  also includes pores  108 , which presents a porous and compressible structure to the component. In some instances, the pores  108  have pore size within the range of from about 10 to about 20 microns. 
     The sponge-like component  102  is a resilient compressible material, which may assist the sponge-like component  102  to conform to the varying size and shape of the LAA. The sponge-like component  102  may have sufficient porosity to allow blood to pass freely through it and yet the pores are sufficiently small to trap undesirable particles. Exemplary materials appropriate for this purpose include urethane, silicone, cellulose, or polyethylene, with urethane and polyethylene being preferred. 
     Here, the material employed to manufacture the sponge-like component  102  may be made from metals, polymers, biodegradable biomaterials such as polylactic acid, biodegradable polymers (biopolymers), injectable and biodegradable gels, poly(ethylene glycol) (PEG)/Polyester, magnesium-based material or other appropriate materials. In addition, the material may be elastic or resilient, which may allow the device to return to a preset expanded configuration for deployment following passage in a compressed configuration through a delivery catheter. One class of such material may include shape memory alloys such as Nitinol and the like. 
     In one exemplary embodiment, the sponge-like component  102  may be impregnated with a therapeutic agent or solution, which may speed up the occlusion of LAA cavity. Exemplary therapeutic agent may include heparin, or any other suitable agents known to the art. Alternatively, sponge-like component  102  may include suitable therapeutic coatings. In some embodiments, the sponge-like component may be doped with a radiopaque material such as gold or platinum. 
     As already discussed, the medical device  100  is compressible and resilient in nature. In general, the medical device  100  is compressed during delivery and once deployed, the medical device  100  expands to conform to the LAA cavity and occlude the ostium. For deployment purposes, the sponge-like component is compressed. Different mechanisms known to those skilled in the art may be employed for deployment. The following section describes one such mechanism using a catheter. 
       FIG. 2  illustrates the sponge-like component  102  disposed within a delivery catheter  200  according to an embodiment of the present disclosure. Catheter  200  includes a proximal end  201 , a distal end  203 , and a lumen  202  extending between the proximal and distal ends  201 ,  203 . Here, the lumen  202  may be substantially circular and it may be made of any suitable biocompatible material such as polyurethane, plastic, or any other suitable material. Other suitable cross-sectional shapes such as elliptical, oval, polygonal, or irregular may also be contemplated. The diameter of the lumen may be uniform along its length or may vary. For example, the distal end of the catheter  200  may taper, allowing convenient insertion of the catheter within the body. Moreover, the lumen  202  may be flexible along its entire length or adapted for flexure along portions of its length. Alternatively, the lumen&#39;s distal end may be flexible while the remaining lumen may be rigid. Flexibility allows the lumen  202  to maneuver within the circuitous vasculature, while rigidity provides the necessary force to urge the lumen  202  forward. 
     In some instances, catheter  200  may require an appropriate guide wire or guiding member to deploy the medical device  100  into the patient&#39;s LAA. Therefore, the lumen  202  contains a push wire  204 , which is slideably disposed within a lumen  202  of the delivery catheter  200 . The push wire  204  serves to apply axial force on the compressed sponge-like component  102 , which deploys the sponge like component within the LAA. Here, push wire  204  is connected removably to the proximal end  104  of the sponge-like component  102 , and the physician may retract the push wire  204  inside the catheter lumen  202  once the sponge-like component  102  is deployed. 
     The push wire  204  may be coupled to the sponge-like component  102  using a connecting member  206 . The connecting member  206  may be any suitable member that facilitates detachable connection between the two members. In one embodiment of the present disclosure, the connecting member  206  may include a male thread  208  at the proximal end of the push wire  204  and a corresponding female thread  210  such as, but not limited to, a nut attached to the proximal end of the sponge-like component  102 . The connecting member may assist holding the sponge-like component  102  in the compressed configuration inside the catheter lumen  202 , and it may help release the sponge-like component  102  in its expanded state once deployed. It will be understood that other mechanisms to provide a detachable connection between the push wire  204  and the sponge-like component may be contemplated. Such mechanisms may include a magnetic connection, or a snap-fit method, or any other suitable mechanism known in the art. 
       FIGS. 3-5  illustrate an exemplary method of using the medical device  100  to occlude the LAA opening  302  of a patient&#39;s heart  300 . 
     As depicted in  FIG. 3 , catheter  200  is inserted within a patient&#39;s heart  300  through the trans-septal crossing. Medical device  100  may be disposed within the catheter&#39;s lumen  202  or may be inserted within the lumen  202  once the catheter&#39;s distal end reaches close to LAA opening  302 . During the insertion process the medical device  100  remains compressed within the lumen  202 . Once the catheter  200  is appropriately deployed, the medical device  100  extends from the distal end of the catheter  200  and expands to conform the LAA opening  302 . 
     Deployment of the medical device  100  may be accomplished using suitable mechanism. For example, the push wire  204  may be connected to the proximal end of the medical device  100 , and this push wire  204  may extend out the proximal end of the catheter  200 . A surgeon may push the push wire  204  to extend the medical device  100  from the distal end of the catheter  200  or pull the catheter  200  while leaving the push wire  204  and medical device in position. In some instances, the medical device  100  may not be appropriately delivered to the LAA opening  302 . In that event, push wire  204  may then be used to retract the device  100  within the catheter  200  and to reposition and redeploy it, as desired. 
     Upon medical device  100  deployment, the push wire  204  may be detached from the proximal end of the medical device  100 , and the catheter  200  along with the push wire  204  may be retracted from the body. To this end, the proximal end  104  of the sponge-like component  102  may be coupled to the distal end of the push wire  204  using a connecting member  206  that facilitates detachable connection between the two devices. The connecting member may switch between a locked configuration, which may include fastening the male threads  208  over the female threads  210  to hold the device  100  within the lumen  202  and, an unlocked configuration, which may include disengagement of the two threads to releases the device  100  upon deployment. As depicted in  FIG. 3 , connecting member  206  may be present in a locked configuration, which includes fastening of the male threads  208  along its axis through the fixed female threads  210 . Here, fastening of male threads  208  over the female threads  210  involves clockwise rotation of the male thread along its axis. Further, it may be understood that other rotation movements may also be contemplated such as anticlockwise rotation or the like. Alternatively, connecting member  206  may switch to the unlocked configuration shown in  FIG. 4 , which include detachment of the sponge-like component  102  and push wire  204 , when deployed within the patient&#39;s LAA. 
     Once catheter  200  approaches the LAA opening  302 , the device  100  is advanced from the distal end  203  of the catheter  200  and expands to conform to the LAA opening  302 .  FIG. 4  depicts this transition from a compressed configuration to an expanded configuration of sponge-like component  102 . Here, the distal end  203  of the delivery catheter  200  has passed through the septum of the patient&#39;s heart  300  and is disposed adjacent the opening of the patient&#39;s LAA  302 . The proximal end of the push wire  204  extends from the lumen  202  of the delivery catheter such as the proximal end of the delivery catheter is arranged to allow rotational and axial movement of the push wire  204  while preventing blood or other bodily fluids from leaking between the lumen  202  and the push wire  204 . 
     As further shown in  FIG. 4 , the connecting member  206  depicts unlocked configuration, which include disengaging the male threads  208  and female threads  210 . Therefore, detaching the connecting member may uncouple the sponge-like component from the push wire, which may assist the partially expanded sponge-like component  102  to conform to the LAA  302  cavity, as shown in  FIG. 5 . Finally, the push wire  204  may be retracted within the catheter lumen  202 . 
     Advancing the medical device  100  from the distal end of the catheter results in its expansion. The sponge-like component  102  contributes to the expandability of the medical device  100 , which then expands to block the LAA opening  302 . Once the medical device  100  is appropriately deployed in the LAA  302 , the push wire  204  is detached from the device  100 , and the catheter  200 , along with the push wire  204 , is retrieved from the body. 
     In the illustrated embodiments, the expanded sponge-like component  102  includes a rough surface, which may assist holding the sponge-like component inside the cavity by bearing against the LAA walls with sufficient force to anchor it in place. One skilled in the art may appreciate that the surface roughness of the sponge-like component  102  may be improved by including various other mechanisms known to the art. Such mechanism may include, but are not limited to, adding spikes, hooks or other components known in the art to the surface of the sponge-like component  102 . In present embodiment, the force exerted on the wall of LAA  302  by the expanded sponge-like component  102  within the range of from about 180 to about 250 grams. One skilled in the art may contemplate other sizes of the sponge-like component, which may impart a force sufficient not to damage the LAA  302  wall cavity while holding the sponge-like component in position. 
     Those skilled in the art will recognize that the present disclosure may be manifested in a variety of forms other than the specific embodiments described and contemplated herein. Accordingly, departure in forma and detail may be made without departing from the scope and spirit of the present disclosure as described in the appended claims.