Patent Publication Number: US-2020289128-A1

Title: Left atrial appendage occluder

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a continuation application of a non-provisional application having U.S. patent application Ser. No. 15/035,824 filed on May 11, 2016, and the National Phase application of International Application No. PCT/CN2014/090605 filed on Nov. 7, 2014, which claims priority to Chinese Application No. 201310567987.0 filed on Nov. 14, 2013, the contents of which are all incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates to medical devices, in particular to an occluder which is capable of being transferred to a predetermined position in the human body by an interventional catheterization technique, and preventing stroke caused by thrombosis in the left atrial appendage due to atrial fibrillation. 
     BACKGROUND OF THE PRESENT INVENTION 
     At present, therapy for treating diseases by interventional catheterization technique is widely applied, and a variety of materials, apparatuses and drugs are placed into the heart, arteries and veins of the human body through this treatment. 
     When an occluder is placed into the heart, arteries, veins, and left atrial appendage by the catheter interventional method, due to complex anatomical structures of the heart, the artery and vein blood vessels, especially the left atrial appendage, the apparatus is required to be delivered to a predetermined position accurately, and to be well-adapted to the anatomical structure, mechanics requirements and hemodynamics requirements of the predetermined position at the same time. Under the premise of only generating microtrauma to the human body, firstly, the skin near the blood vessel is punctured, a guide wire enters into the blood vessel from the puncturing site, one end of a catheter is delivered to the predetermined position under the guidance of the guide wire, and the other end thereof is reserved in vitro, and then the apparatus is transferred to the predetermined position by using the catheter and a pusher. During such procedure, a fine flexible catheter is required, while the catheter and the guide wire are designed to be visualized under the X ray. Once the catheter reaches the predetermined position, the guide wire is removed, and the apparatus is guided to the tail end of the catheter by using an access established by the catheter through the pusher; when being completely exposed from the tail end of the catheter, the apparatus is released from the pusher. 
     For example, the occluder is placed into the left atrial appendage by using the catheter interventional method, in order to prevent thrombosis from the left atrial appendage causing atrial fibrillation, and stroke caused by ascending the thrombus to the brain; or in order to prevent systemic embolism caused by the thrombus reaching to other parts of the body through a body blood circulation system, Placing the occluder into the left atrial appendage to occlude the left atrial appendage and block the blood flow entering into the left atrial appendage can eliminate the risk of thrombosis formed in the left atrial appendage, thus preventing stroke. At present, the apparatuses are usually threadedly connected to a delivery sheath. 
     With reference to  FIG. 1  and  FIG. 2 ,  FIG. 1  shows an existing left atrial appendage occluder located in an anatomical structure of the heart and the left atrial appendage, and  FIG. 2  is a structure diagram of the existing left atrial appendage occluder, wherein  01  means left atrium,  02  means left atrial appendage and  03  means left atrial appendage cavity wall. The occluder includes a sealing disc  11  and a fixing bracket  12  which consists of a plurality of supports  13 ; a fixing anchor (or referred to as anchoring barb)  15  is arranged on each of the supports  13 , and the supports  13  are extended to ball ends of support ends  14  starting from a position where the fixing anchor  15  is located, and spaced from each other; a connecting nut  16  is arranged on the sealing disc  11  of the left atrial appendage occluder. The occluder has good elasticity, may be contained in a sheath with width of 2 to 4 mm, transferred into the left atrial appendage  02  through the vascular access, and slowly retreated from the sheath tube; the fixing bracket  12  of the occluder will be unfolded in the left atrial appendage cavity, and the supports  13  of the fixing bracket  12  will be pressed on the left atrial wall by adapting to the shape of the left atrial appendage  02 , while the fixing anchor  15  of the supports  13  will be penetrated into the inner wall  03  of the left atrial appendage, thus guaranteeing reliable fixation, and, the sealing disc  11  is covered on the ostium of the left atrial appendage  02 , as shown in  FIG. 1 . Finally, a steel cable connected to the left atrial appendage occluder is released, thus occluding the left atrial appendage and blocking the blood flow entering into the left atrial appendage. 
     The above left atrial appendage occluder has the following limitations: the support ends of the fixing bracket are spaced and suspended. When the fixing bracket is pushed out after being placed into the sheath tube, the risk of twisting between the support ends exists, resulting in possible failure of the fixing bracket to unfold properly, and therefore a failed procedure. 
     SUMMARY OF THE PRESENT INVENTION 
     An object of the present invention is to provide a left atrial appendage occluder, that avoids twisting between the supports. 
     The present technical solution is to provide a left atrial appendage occluder, including a sealing disc and a fixing bracket which is connected to the sealing disc and located at one side of the sealing disc; the fixing bracket including a connecting portion connected to the sealing disc, and a plurality of supports; after radiating out distally from the connecting portion and coordinating to form a recessed area, the plurality of supports are bent to extend proximally to form a plurality of spaced suspended supporting segments, the supporting segment being provided with at least one anchoring barb facing the sealing disc; the left atrial appendage occluder further includes a thin film, all the supports being connected in series through the thin film. 
     In the left atrial appendage occluder according to an embodiment of the present invention, the thin film includes at least one annular thin film which is fixed on all the supports and encircles the recessed area to expose the whole or a part of the recessed area. 
     In the left atrial appendage occluder according to an embodiment of the present invention, the thin film includes a spherical thin film further covering the recessed area. 
     In the left atrial appendage occluder according to an embodiment of the present invention, at least one anchoring barb penetrates through the thin film. 
     In the left atrial appendage occluder according to an embodiment of the present invention, the thickness of a portion of the thin film located surrounding the anchoring barb is larger than or equal to that of the rest portion of the thin film. 
     In the left atrial appendage occluder according to an embodiment of the present invention, the supports are further provided with a plurality of fixing holes, through which the thin film is fixed on the supports by suturing. 
     In the left atrial appendage occluder according to an embodiment of the present invention, the thin film is adhered on the supports through biocompatible adhesive. 
     In the left atrial appendage occluder according to an embodiment of the present invention, a proximal edge of the thin film is 1 to 5 mm away from a root of the anchoring barb. 
     In the left atrial appendage occluder according to an embodiment of the present invention, after penetrating through the thin film, the length of the anchoring barb extending outside is between 1 mm and 3 mm. 
     In the left atrial appendage occluder according to an embodiment of the present invention, the thin film is made of PET or PTFE or silica gel. 
     In the left atrial appendage occluder according to an embodiment of the present invention, the thin film includes a plurality of overlapped thin film layers. 
     In the left atrial appendage occluder according to an embodiment of the present invention, the thin film includes multiple sheets of thin film distributed at interval on the fixing bracket along the direction from the distal end to the proximal end. 
     In the left atrial appendage occluder according to an embodiment of the present invention, the number of the supports is six, eight, nine, twelve, or sixteen. 
     In the left atrial appendage occluder according to an embodiment of the present invention, the anchoring barb is formed on the supports by cutting. 
     In the left atrial appendage occluder according to an embodiment of the present invention, the supports include a plurality of guiding segments, a plurality of branching segments and a plurality of suspended supporting segments successively radiating out distally from the connecting portion. 
     In the left atrial appendage occluder according to an embodiment of the present invention, the plurality of guiding segments are coordinated with each other to form a recessed area by regarding the connecting portion as a center; one end of each guiding segment away from the connecting portion is respectively connected to two branching segments: the two branching segments form an included angle; each branching segment is intersected with one of the two branching segments corresponding to the adjacent guiding segment which is adjacent thereto, and bent to extend proximally to form the suspended supporting segments. 
     In the left atrial appendage occluder according to an embodiment of the present invention, the suspended supporting segments are approximately U-shaped. 
     In the left atrial appendage occluder according to an embodiment of the present invention, the tail ends of the suspended supporting segments are provided with spheres. 
     In the left atrial appendage occluder according to an embodiment of the present invention, the supports are formed by cutting a nickel-titanium tube from one end thereof along the direction towards another end, expanded by using a mould, and shaped by heat treatment; the portion of the nickel-titanium tube which is not cut off forms the connecting portion. 
     Compared with the prior art, the technical solution employed by the present invention at least has the following advantages: the left atrial appendage occluder further includes the thin film through which all the supports are connected in series, the present invention effectively restrains the relative position and relative movement between the supporting segments through the thin film, thus avoiding twisting of the supporting segments when the fixing bracket is pushed out and released from a delivery sheath. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be further illustrated as below with reference to accompanying drawings and embodiments, in the drawings: 
         FIG. 1  is a diagram showing an existing left atrial appendage occluder in an anatomical structure of the heart and the left atrial appendage: 
         FIG. 2  is a structure diagram of the existing left atrial appendage occluder; 
         FIG. 3  is a schematic diagram of a left atrial appendage occluder provided by an embodiment of the present invention; 
         FIG. 4  is a schematic diagram of the left atrial appendage occluder as shown in  FIG. 3  from another view; 
         FIG. 5  shows a schematic diagram of a fixing bracket in  FIG. 3 ; 
         FIG. 6  shows a schematic diagram of a fixing bracket in  FIG. 3 ; 
         FIG. 7  shows a local diagram of a support and a thin film in  FIG. 3 ; 
         FIG. 8  shows a schematic diagram of the left atrial appendage occluder as shown in  FIG. 3  after being released in the left atrial appendage; 
         FIG. 9  is a schematic diagram of a left atrial appendage occluder provided by another embodiment of the present invention: 
         FIG. 10  is a schematic diagram of the left atrial appendage occluder as shown in  FIG. 9  from another view; 
         FIG. 11  is a schematic diagram of the left atrial appendage occluder as shown in  FIG. 9  after being released in the left atrial appendage; and 
         FIG. 12  is a schematic diagram of the left atrial appendage occluder as shown in  FIG. 9  not completely occluding an entrance of the left atrial appendage in the process of releasing in the left atrial appendage. 
     
    
    
     DETAILED DESCRIPTION OF THE PRESENT INVENTION 
     In order to understand the object, the technical solution and the advantages of the present invention more clearly, the present invention will be further described in detail with reference to the accompanying drawings and embodiments, it should be understood that the specific embodiments described hereinafter are only used for explaining the present invention, but not for limiting the present invention. 
     In order to more clearly describe the structure of the left atrial appendage occluder (hereinafter referred to as occluder), terms such as ‘distal end’ and ‘proximal end” are defined. The above terms are commonly used in the field of interventional medical device. Specifically, the term ‘distal end’ means the end away from an operator during surgery, and the term ‘proximal end’ means the end near the operator during surgery. 
     With reference to  FIG. 3  to  FIG. 8 , an embodiment of the present invention provides a left atrial appendage occluder  10  that includes a sealing disc  100 , a fixing bracket  200  connected to the sealing disc  100  and located at one side of the sealing disc  100 , and a thin film  300  fixed on the fixing bracket  200 . 
     The sealing disc  100  is formed by braiding a nickel titanium wire or a biocompatible polymer wire, and located at the proximal end relative to the fixing bracket  200 . 
     The fixing bracket  200  includes a connecting portion  210  connected to the sealing disc  100 , and a plurality of supports  220 . After radiating out distally from the connecting portion  210  and coordinating to form a recessed area  221 , the plurality of supports  220  are bent to extend proximally to form a plurality of spaced suspended supporting segments  222 , the supporting segments  222  are provided with at least one anchoring barb  223  facing the sealing disc  100 . 
     In actual manufacturing, the plurality of supports  220  may be formed by cutting a nickel titanium tube from one end thereof along the direction towards the other end, expanded by using a mould, and shaped by heat treatment; the portion of the nickel-titanium tube which is not cut off forms the connecting portion  210 . The number of the supports  220  may be determined according to the requirements of the mechanical properties and size specifications, such as six, eight, nine, twelve, and sixteen, etc. During the cutting, the anchoring barb  223  arranged on the supports  220  is cut off at the same time. 
     With reference to  FIG. 5  to  FIG. 0 , the supports  220  include a plurality of guiding segments  224 , a plurality of branching segments  225  and a plurality of suspended supporting segments  222  successively radiating out distally from the connecting portion  210 , The plurality of guiding segments  224  are coordinated with each other to form a recessed area  221  by regarding the connecting portion  210  as a center. One end of each guiding segment  224  away from the connecting portion  210  is respectively connected to two branching segments  225 . The two branching segments  225  form an included angle, preferably, an acute angle. Each branching segment  225  is intersected with one of the two branching segments corresponding to the adjacent guiding segment  224  which is adjacent thereto, and bent to extend proximally to form the suspended supporting segments  222 . The supporting segments  222  are spaced from each other. In other words, each guiding segment  224 , encircling the connecting portion  210 , terminates into the two branching segments  225  connected thereto, to form a similar V-shaped or herringbone shape; and two adjacent V-shaped or herringbone structures, after being connected to one end away from the connecting portion  210 , are extended to form a supporting segment  222 . The supporting segment  222  is approximately U-shaped, one end thereof connected to the branching segments  225  is provided with an anchoring barb  223 , and the suspended end thereof is processed to form a sphere  226 . With reference to  FIG. 6 , the ends of the guiding segments  224  and the branching segments  225  near the supporting segment  222  are all provided with a plurality of fixing holes  227 . 
     Still as shown in  FIG. 3  and  FIG. 4 , the thin film  300  is usually made of PET or PTFE or silica gel material, and may also be made of other thin film with biocompatibility and physical performance meeting the requirements. The thin film  300  includes an annular thin film fixed on all the branching segments  225  of the fixing bracket  200  in a manner of coordination of the anchoring barb  223  and suturing, thus being connected in series to all the supports  220  to expose the whole or a part of the recessed area  221 . After the occluder  10  is released in the left atrial appendage, the thin film  300  constitutes the outer surfaces of the supports  220  in contact with the inner wall of the left atrial appendage. The suturing means that the suture passes through the fixing holes  227  and then passes through the annular thin film  300 , and then is knotted to fix the thin film  300 . 
     As shown in  FIG. 7 , the width of the thin film  300  may be determined by a position from the anchoring barb  223  to the fixing holes  227  of the supports  220  of the fixing bracket  200  and the annular thin film  300 . In the present embodiment, the thin film  300  may proximally extend 1 to 5 mm from the root of the anchoring barb  223 , and the thin film  300  may distally extend 2 to 10 mm from the fixing holes  227  of the supports  220  and the annular thin film  300 . The thickness of the thin film  300  shall meet the following conditions: after penetrating through the thin film  300 , the length of the anchoring barb  223  extending out the thin film  300  is equal to or more than 1 mm and less than or equal to 3 mm, in order to ensure that the anchoring barb  223  will not fall off after being inserted into the left atrial appendage. 
       FIG. 8  shows a schematic diagram of the left atrial appendage occluder released in the left atrial appendage, as shown in  FIG. 8 , when the fixing bracket  200  is placed into the left atrial appendage, the fixing bracket  200  and the annular thin film  300  are unfolded in the state shown in  FIG. 8 , the supports  220  of the fixing bracket  200  and the annular thin film  300  are laminated together in the inner wall  03  of the left atrial appendage, the contact surface between the fixing bracket  200  and inner wall  03  is a cylindrical surface. This is compared with the existing left atrial appendage occluder as shown in  FIG. 1  in which only each support  220  and the inner wall  03  are in contact, the contact area being enlarged dozens of times in this way, the stress is more evenly distributed along the inner wall  03  so that the penetrating length of the anchoring barbs  223  on the supports  220  are approximately same into the inner wall  03 . At the same time, the stress per unit area is smaller, thus avoiding damage to the inner wall  03  caused by excessive stress on a certain site. 
     Moreover, the thin film  300  plays a role of effectively restraining the relative position and relative movement between the supports  220 . The thin film  300  has soft, thin, compressible and elastic characteristics, so that the thin film  300  can be always retained on the supports  220  and folded and unfolded along with the supports  220  in the process of placing the fixing bracket  200  into a delivery sheath and then pushing out from the delivery sheath, thus reducing or even avoiding the risk of twisting of the supports  220 , and ensuring smooth operation of the procedure. 
     Further, due to the structure and size characteristics of the annular thin film  300 , the edge thereof is at a certain distance from the root of the anchoring barb  223 , when the anchoring barb  223  is penetrated into the inner wall  03  of the left atrial appendage to a certain depth, the annular thin film  300  will inhibit the anchoring barb  23  from moving deeply into the wall  03  such that the depth of the anchoring barb  223  penetrated into the wall  03  is controllable and extensive damage to the wall  03  caused by uneven stressing is decreased. In addition, in an extreme instance, such as the wall  03  is punctured by an anchoring barb  223 , in accordance with the existing left atrial appendage occluder, blood will run out from the wall  03  and flow inside the left atrial appendage and then be seeped into the pericardial cavity from the pierced position, resulting in pericardial effusion, seriously resulting in cardiac arrest and threatening life. But for the present embodiment, once the wall  03  is punctured by the anchoring barb  223 , the thin film  300  will immediately cover the punctured position while facilitating formation of microthrombus nearby, the throughhole resulted from the puncturing is blocked by the thrombus, such that the blood is prevented from seeping into the pericardial cavity, and the risk of pericardial effusion and even cardiac arrest is reduced. At the same time, the thin film can accelerate thrombosis of the blood in the left atrial appendage and then muscularize, and accelerate the process of muscularization of the left atrial appendage. 
     With reference to  FIG. 9  to  FIG. 12 , a left atrial appendage occluder  20  provided by another embodiment of the present invention has a structure similar to that of the left atrial appendage occluder  10 , including a sealing disc  400 , a fixing bracket  500  connected to the sealing disc  400  and located at one side of the sealing disc  400 , and a thin film  600  fixed on the fixing bracket  500 . The difference of the occluder  20  from the left atrial appendage occluder  10  lies in that, the thin film  600  is spherical, a proximal edge thereof is 1 to 5 mm away from the root of an anchoring barb  523 , and a distal part of the thin film  600  covers the whole recessed area (covered, not shown), The thin film  600  and the supports  520  are sutured together through the fixing holes  527 ,  528 . Each group of the fixing holes  527  and  528  is arranged in the same positions on each support  520 . The fixing manner is the same as that of the first embodiment. 
     In addition to the same action mechanism and advantages as the first embodiment, the thin film  600  further has the following characteristics as follows: in some extreme instances, such as shown in  FIG. 12 , the entrance of the left atrial appendage is not completely sealed by the sealing disc  11  of the left atrial appendage occluder, the blood may enter the left atrial appendage along the direction represented by an arrow  05 , at this moment, the thin film  600  in the second embodiment will act as a second barrier near the entrance in the left atrial appendage, thus preventing the blood from entering into a deeper portion of the left atrial appendage and reducing the thrombosis risk. 
     Compared with the above embodiments, the left atrial appendage occluder of the present embodiment is capable of blocking the blood flow entering into a deeper position in the chamber of the left atrial appendage due to the entrance of the left atrial appendage not being completely sealed by the sealing disc  11  of the left atrial appendage occluder, thus reducing thrombosis risk. 
     It is worth mentioning that, the thin film may have different thicknesses according to different areas in other embodiments of the present invention, for example, the thickness of a portion of the thin film located surrounding the anchoring barb is larger than or equal to that of the other portions of the thin film. Thus, once the wall of the left atrial appendage is punctured by the anchoring barb, the thickened thin film located surrounding the anchoring barb will more effectively prevent hemorrhage after the anchoring barb penetrates into the left atrial appendage, and accelerate thrombosis. In other embodiments, the thin film comprises laminated films, and more thin film layers are located surrounding the anchoring barb. For example, the thin film may include a first thin film layer which is an hemispherical thin film and a second thin film layer which is an annular thin film, the first thin film layer and the second thin film layer are laminated in the area surrounding the anchoring barb, to increase the thickness of the thin film in the area surrounding the anchoring barb, in other embodiments, the thin film includes multiple sheets of thin film distributed at interval on the fixing bracket along the direction from the distal end to the proximal end. 
     The thin film can be fixed in any suitable position of the supports, such as fixed at at least one of the recessed area, the guiding segments, the branching segments and the supporting segments, as long as the supports under a natural state are connected in series and fixed to the thin film. In addition, regardless of whether the anchoring barb is pierced through the thin film or not, the thin film may also be fixed on the supports in other ways except through suture. For example, the thin film can be adhered on the fixing bracket by biological glue. If the thin film is made of silica gel film, the liquid silica gel raw material can be adhered on the supports by heat treatment. 
     The above descriptions are just preferred embodiments of the present invention, but not for limiting the present invention. Any modification, equivalent replacement and improvement done within the spirit and principle of the present invention should be regarded as falling into the protection scope of the present invention.