Abstract:
Disclosed herein are devices and methods for occluding intracardiac defects, such as a patent foramen ovale (PFO). The devices according to the invention have various features to improve flexibility and to enhance conformability of the device to the defect, including the incorporation of braided or multi-stranded wire. The invention also contemplates methods of making these devices.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims priority to and the benefit of U.S. Provisional Patent Application Ser. No. 60/662,780, filed on Mar. 17, 2005, the entire disclosure of which is incorporated by reference herein. 
     
    
     TECHNICAL FIELD OF THE INVENTION  
       [0002]     The invention generally relates to devices and related methods for treating intracardiac defects. More particularly, the invention provides an intracardiac occluder for the percutaneous closure of intracardiac defects, including patent foramen ovale (PFO).  
       BACKGROUND OF THE INVENTION  
       [0003]     The human heart is divided into four compartments or chambers. The left and right atria are located in the upper portion of the heart and the left and right ventricles are located in the lower portion of the heart. The left and right atria are separated from each other by a muscular wall, the intra-atrial septum, while the ventricles are separated by the intraventricular septum.  
         [0004]     Either congenitally or by acquisition, abnormal openings, holes, or shunts can occur between the chambers of the heart or the great vessels, causing blood to flow therethrough. Such deformities are usually congenital and originate during fetal life when the heart forms from a folded tube into a four chambered, two unit system. The deformities result from the incomplete formation of the septum, or muscular wall, between the chambers of the heart and can cause significant problems. Ultimately, the deformities add strain on the heart, which may result in heart failure if they are not corrected.  
         [0005]     One such deformity or defect, a patent foramen ovale, is a persistent, one-way, usually flap-like opening in the wall between the right atrium and left atrium of the heart. Since left atrial pressure is normally higher than right atrial pressure, the flap typically stays closed. Under certain conditions, however, right atrial pressure exceeds left atrial pressure, creating the possibility for right to left shunting that can allow blood clots to enter the systemic circulation. This is particularly worrisome to patients who are prone to forming venous thrombus, such as those with deep vein thrombosis or clotting abnormalities.  
         [0006]     Nonsurgical (i.e., percutaneous) closure of a PFO, as well as similar intracardiac defects such as atrial septal defects, ventricular septal defects, and closure of left atrial appendages, is possible using a variety of mechanical closure devices. These devices, which allow patients to avoid the potential side effects often associated with standard anticoagulation therapies, typically consist of a metallic structural framework that is combined with a synthetic or biological tissue scaffold material. The support structure of the septal occluder is often stiff and rigid, lacking flexibility to conform with septal defects, resulting in trauma to surrounding tissues, chronic inflammation, residual leaks and reduced rates of defect closure.  
       SUMMARY OF THE INVENTION  
       [0007]     The present invention provides a device for occluding intracardiac defects, as well as a method for making the device. The device includes a flexible and resilient support structure coupled with a scaffold material to create a flexible septal occluder. The support structure comprises a variety of modifications that enhance the flexibility of the device.  
         [0008]     In one aspect, the invention is directed to a flexible septal occluder. In one embodiment of this aspect of the invention, a flexible septal occluder comprises a first portion and a second portion joined by a central body portion. The first portion comprises a plurality of arms with a flexural point disposed on at least one of the arms. The second portion also comprises a plurality of arms. At least one of the arms on the first portion comprises a plurality of strands forming a bundle of strands interrupted at the flexural point by a gap in strands. Further features of this embodiment include the following. For example, the embodiment may feature more than one flexural point disposed on at least one arm of the first portion. At least one flexural point may also be disposed on each arm of the first portion. In addition, a plurality of strands comprising the arm may run parallel to one another along the lengthwise axis of the arm. The flexible septal occluder may also comprise at least one flexural point disposed on at least one arm of the second portion. Additional features may include one or more flexural points disposed on the central body portion of the flexible septal occluder. The plurality of strands comprising the central body portion may also run parallel to one another along the lengthwise axis of the central body portion.  
         [0009]     In another embodiment of this aspect of the invention, the flexible septal occluder comprises a first portion comprising a plurality of arms. At least one of said arms comprises a plurality of strands forming a bundle of strands comprising a first loop and a second loop. The first portion is joined by a central body portion to a second portion comprising a plurality of arms. The plurality of strands comprises a first loop and a second loop with the first loop comprising a different diameter than said second loop. Further features of this embodiment include the following. For example, the first loop and the second loop may be adjacent. The diameter of the first loop may have the same diameter as the diameter of another loop disposed on the first portion, while a further feature requires that the first loop and the another loop are adjacent. According to another feature of the embodiment, the second portion of the flexible septal occluder comprises a plurality of strands forming a bundle of strands comprising a first loop and a second loop. An additional feature may include at least one of the plurality of arms of the first portion or the second portion comprising a coil, while a further feature includes a central body portion or both the central body portion and at least one of the plurality of arms comprising a coil.  
         [0010]     In yet another embodiment of this aspect of the invention, the flexible septal occluder comprises a first portion comprising a plurality of arms, a second portion comprising a plurality of arms, and a central body portion. The first and second portions are joined by the central body portion. The central body portion comprises a plurality of strands forming a bundle of strands forming a first loop and a second loop. The first loop of the central body portion comprises a different diameter than the second loop. Further features of this embodiment include the following. For example, the first loop and the second loop of the central body portion may be adjacent. The embodiment may also feature the central body portion comprising another loop with the same diameter as the first loop. According to another feature of the embodiment, the first loop and the other loop may be adjacent. An additional feature may include at least one of the plurality of arms of the first portion or the second portion comprising a coil, while a further feature includes a central body portion or both the central body portion and at least one of the plurality of arms comprising a coil.  
         [0011]     In another embodiment of this aspect of the invention, a flexible septal occluder comprises a first portion comprising a plurality of arms having a plurality of strands, a second portion comprising a plurality of arms having a plurality of strands, and a central body portion comprising a plurality strands. One of the strands of the first, second, or central body portions comprises a non-circular cross-section. Further features of this embodiment include the following. For example, the non-circular cross-section may be triangular, but may also be selected from the group consisting of a square, a rectangular, a triangular, a hexagonal, an elliptical, and a rhomboidal cross-section. As an additional feature, all of the strands of the first portion, second portion or central body portions may comprise the same non-circular cross-section, whereas alternatively, the embodiment may feature at least one of said first portion, second portion, or central body portions comprising at least two strands, with each of the two strands having different non-circular cross-sections.  
         [0012]     In another embodiment of this aspect of the invention, the flexible septal occluder comprises a first portion comprising a plurality of arms, a second portion comprising a plurality of arms, and a central body portion comprising a coil. As a further feature, at least a portion of one of the plurality of arms of the first portion or the second portion of the flexible septal occluder comprises a coil.  
         [0013]     A further aspect of the invention is a method for making a flexible septal occluder. The method comprises providing a first portion comprising a plurality of arms, said arms comprising a first wire and a second wire, and providing a second portion comprising a plurality of arms, said arms comprising a first wire and a second wire, and providing a central body portion comprising a first wire and a second wire, wherein said first wire of said first portion, second portion, or central body portion is annealed at a first temperature and said second wire of said first portion, second portion or central portion is annealed at a second temperature. The first portion, second portion, and central body portion are assembled to form the flexible septal occluder. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]     In the drawings, like reference characters generally refer to the same parts throughout the different views. Also, the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention.  
         [0015]      FIG. 1  is a cutaway view of the heart illustrating an intracardiac defect.  
         [0016]      FIG. 2  depicts a perspective view of an intracardiac occluder according to an illustrative embodiment of the invention.  
         [0017]      FIG. 3  depicts a top plan view of a portion of an arm of a septal occluder made from a multi-strand bundle where the bundle is parted at a flexural point to create a gap in the strands according to an illustrative embodiment of the invention.  
         [0018]      FIG. 4  depicts a top plan view of a portion of an arm of a septal occluder made from a multi-strand bundle where the bundle is parted at a flexural point to create a gap in the strands according to another illustrative embodiment of the invention.  
         [0019]      FIG. 5  depicts a top plan view of a portion of an arm of a septal occluder made from a plurality of multi-strand bundles forming a cable where the cable is parted at a flexural point to create a gap in the strands according to another illustrative embodiment of the invention.  
         [0020]      FIG. 6  depicts an exemplary cross-sectional view of the portion of the arm of the septal occluder of  FIG. 5  according to an illustrative embodiment of the invention.  
         [0021]      FIG. 7  depicts a top plan view of an exemplary occlusion shell of an exemplary intracardiac occluder with arms constructed of the multi-strand bundle shown in  FIG. 3  according to another illustrative embodiment of the invention.  
         [0022]      FIG. 8A  depicts a top view of a portion of an arm of a septal occluder made from a multi-strand bundle forming a single loop, while  FIG. 8B  depicts a side view of the portion of the arm of  FIG. 8A , according to an illustrative embodiment of the invention.  
         [0023]      FIG. 9A  depicts a top view of an occlusion shell of an illustrative intracardiac occluder with arms made from multi-strand bundles with loops as shown in  FIG. 8A , while  FIG. 9B  depicts a side view of the exemplary occlusion shell and illustrative intracardiac occluder shown in  FIG. 9A , where the arms of the occlusion shells are made from multi-strand bundles with loops as shown in  FIG. 8A  according to an illustrative embodiment of the invention.  
         [0024]      FIG. 10A  depicts a side view of a portion of an arm of a septal occluder made from a multi-strand bundle having multiple loops at the same point on the length of the arm forming a coil, while  FIG. 10B  depicts a top view of the portion of the arm shown in  FIG. 10A , according to an illustrative embodiment of the invention.  
         [0025]      FIG. 11A  depicts a side view of a portion of an arm of a septal occluder made from a multi-strand bundle including loops of varying diameters along the length of the bundle, while  
         [0026]      FIG. 11B  depicts a top plan view of the portion of the arm of  FIG. 11A , according to an illustrative embodiment of the invention.  
         [0027]      FIG. 12A  also depicts a side view of a portion of an arm of a septal occluder made from a multi-strand bundle comprising loops of varying diameters forming a coil along the length of the bundle, while  FIG. 12B  depicts a top plan view of the arm having loops forming a coil of  FIG. 12A , according to another illustrative embodiment of the invention.  
         [0028]      FIG. 13  depicts a portion of an arm of a septal occluder made from a multi-strand bundle, according to an illustrative embodiment of the invention.  
         [0029]      FIGS. 14-17  depict various cross-sectional views of the strands that make up the arm of  FIG. 13 , according to illustrative embodiments of the invention. In  FIG. 14 , the cross-section of the strands is rectangular, while in  FIGS. 15 and 17 , the cross-section of the strands is triangular. In  FIG. 16 , the cross-section of the strands is hexagonal. The cross-sections depicted in  FIGS. 14-17  are according to illustrative embodiments of the invention.  
         [0030]      FIGS. 18-20  each depict a portion of an arm of a septal occluder made of a multi-stranded bundle, wherein the pitch of the component strands in each bundle differs from the pitch of the strands in the other exemplary bundles shown, according to illustrative embodiments of the invention.  
         [0031]     FIGS.  21 A-E depict multiple steps used to insert a septal occluder into a defect in a patient&#39;s heart according to an illustrative embodiment of the invention in a defect in a patient&#39;s heart. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0032]     The present invention is related to flexible intracardiac occluders, such as septal occluders, for the repair of intracardiac defects, such as, for example, a patent foramen ovale (PFO), an atrial septal defect, a ventricular septal defect, and left atrial appendages. All of the following embodiments of the invention include one or more features on the occluder to enhance flexibility at specific points on the occluder.  
         [0033]      FIG. 1  depicts a cutaway view of a heart  2  illustrating an intracardiac defect  14 . The heart  2  includes a septum  4  that divides the right atrium  12  from the left atrium  6 . The septum  4  includes a septum primum  8 , a septum secundum  10 , and an exemplary intracardiac defect  14 , which is to be corrected by the introduction of an intracardiac occluder of the present invention between the septum primum  8  and the septum secundum  10 . Specifically, a PFO  14  is shown as an opening through the septum  4 . The PFO  14  provides an undesirable communication between the right atrium  12  and the left atrium  6 . Under certain conditions, a PFO  14  in the septum  4  can allow for the shunting of blood from the right atrium  12  to the left atrium  6 . If the PFO  14  is not closed or obstructed in some manner, a patient is placed at high risk for an embolic stroke, migraine, or other physiological condition.  
         [0000]     Septal Occluder  
         [0034]      FIG. 2  depicts a perspective view of an intracardiac occluder  320  according to an illustrative embodiment of the invention. As shown, the intracardiac occluder  320  includes, for example, a proximal occlusion shell  302  (i.e., an occlusion shell that is closest to an operator of the intracardiac occluder  320  (e.g., a physician)), a distal occlusion shell  304 , and a support structure  310 . In one embodiment, the support structure  310  includes a proximal support structure  314  for supporting the proximal occlusion shell  302  and a distal support structure  316  for supporting the distal occlusion shell  304 .  
         [0035]     In one embodiment according to the invention, the support structures  314 ,  316  comprise a plurality of arms, generally,  300 , for example,  300 ,  300 ′,  300 ″,  300 ′″. While the invention also contemplates an occlusion shell with no arms, the support structure  314 ,  316  may have one, two, three, four, five, six, seven, eight, nine, ten, or more arms supporting the occlusion shell  302 ,  304 . Furthermore, while the invention contemplates an intracardiac occluder  320  with only one occlusion shell  302 ,  304 , the invention also contemplates an intracardiac occluder  320  with two occlusion shells  302 ,  304 , for example, a proximal occlusion shell  302  and a distal occlusion shell  304 . In an embodiment where the intracardiac occluder  320  has two occlusion shells  302 ,  304 , the proximal occlusion shell  302  has the same number of arms  300  as the distal occlusion shell  304 , or alternatively, the proximal occlusion shell  302  has a different number of arms  300  than the distal occlusion shell  304 .  
         [0036]     With continued reference to  FIG. 2 , in one embodiment, the proximal occlusion shell  302  and the distal occlusion shell  304  are connected by a central body portion  400 . In a further embodiment, the central body portion  400  joins the center of the proximal occlusion shell  302  to the center of the distal occlusion shell  304 . In yet another embodiment, the occlusion shells  302 ,  304  rotate about the axis of the central body portion  400 . While the occlusion shells  302 ,  304  depicted in  FIG. 2  are rectangular, the shells may be circular, elliptical, square, convex, concave, flat, or be any other functional shape.  
         [0037]     As shown in  FIG. 2 , according to the invention, in one embodiment the occlusion shells  302 ,  304  include a scaffold  315 ,  317  supported by the proximal and distal support structures  314 ,  316 . In one embodiment, the scaffold  315 ,  317  is made from a biological tissue, such as collagen. For example, in one embodiment, the scaffold  315 ,  317  comprises collagen derived from the tunica mucosa layer of the porcine small intestine, or from other sources as described in, for example, U.S. Patent Application Publication No. 2004-0098042, incorporated by reference herein. Alternatively, the scaffold  315 ,  317  of occlusion shells  302 ,  304  is a synthetic scaffold, such as a polyester fabric, expanded polytetrafluoroethylene (ePTFE), polyvinyl alcohol (e.g. Ivalon®), a metal mesh, or a bioresorbable material. In a further embodiment, the scaffold  315  of the proximal occlusion shell  302  is the same material as the scaffold  317  of the distal occlusion shell  304 , while in another embodiment, the scaffold  315  of the proximal occlusion shell  302  is a different material than the scaffold of the distal occlusion shell  304 .  
         [0000]     Multi-Strand Bundles  
         [0038]     A key aspect of the invention is that intracardiac occluders made with single strands of wire or with multi-strand bundles modified according to the invention have improved mechanical properties. Wire strands of the invention may be made from a suitable metal, such as stainless steel, nitinol, or MP35N, or they may be made from a polymer or a bioresorbable material. According to the invention, single strands alone, or multi-strand bundles can be modified to provide beneficial results, such as, improving the flexibility of the intracardiac occluder  320 , enhancing the conformability of the occluder  320  to the intracardiac defect  14 , and enhancing the apposition of the occlusion shells  302 ,  304  to one another and the intracardiac defect  14 , thereby reducing trauma to intracardiac tissues, providing faster rates of tissue ingrowth and hastening defect closure rates. The multi-strand bundles of the invention may be used create the support structure  310  of the intracardiac occluder  320 , including the arms  300  and/or the central body portion  400 .  
         [0039]      FIGS. 3 and 4  depict top plan views of a portion of an arm  300  of a septal occluder  320  made from a multi-strand bundle  41  where the bundle  41  is parted at a flexural point  51  to create a gap  46  in the strands  40  according to an illustrative embodiment of the invention. Multi-strand bundles  41  are created by weaving, braiding, twisting, bundling, winding, or otherwise grouping a plurality of individual wire strands  40  to form a bundle  41  of strands  40  of the arm  300  of the septal occluder  320 . For example,  FIG. 3  depicts an exemplary multi-strand bundle  41  of a portion of an arm  300  according to an illustrative embodiment of the invention in which the strands  40  are twisted together. For example,  FIG. 4  depicts a top plan view of an exemplary multi-strand bundle  41  according to another illustrative embodiment of the invention in which an arm  300  of a septal occluder  320  is made from a multi-strand bundle  41  in which the strands  40  are bundled to run parallel to their lengthwise axis. In a further embodiment, the strands  40  are bundled to run parallel to the lengthwise axis of the arm  30 . As illustrated in  FIGS. 3 and 4 , the arm  300  may include four strands  40  of wire to form a bundle  41 . Alternatively, the arm  300  may include, for example, two, three, five, six, seven, eight, nine, ten or more wire strands  40 .  
         [0040]      FIG. 5  depicts a top plan view of a portion of an arm  300  of a septal occluder  320  made from a plurality of multi-strand bundles  41  forming a cable  49  where the cable  49  is parted at a flexural point  51  to create a gap  46  in the strands  40 , according to an illustrative embodiment of the invention. As shown in  FIG. 5 , an exemplary plurality of multi-strand bundles  41  may be grouped together to form a cable  49  to be used in one or more arms  300 . The plurality of multi-strand bundles  41  forming the cable  49  may also be used to make the central body portion  400  (not shown).  
         [0041]      FIG. 6  depicts an exemplary cross-sectional view of the portion of the arm  300  of the septal occluder  320  illustrated in  FIG. 5 . As shown in  FIG. 6 , three multi-strand bundles  41 , each including three strands  40 , are bundled together to create a cable  49 . The number of bundles in the cable  49  and the number of strands  40  in each of the multi-strand bundles  41  is not limited to what is illustrated in  FIG. 6 . For example, the cable  49  may comprise two, three, four, five or more multi-strand bundles and each of the multi-strand bundles may comprise two, three, four, five or more strands  40  (not shown). Furthermore, each of the multi-strand bundles  41  in the cable  49  need not be the same. For example, in one embodiment, one multi-strand bundle  41  is made of three strands  40 , while another multi-strand bundle is made of seven strands  40  (not shown). Additionally, the multi-strand bundles  41  or cables  49  can be used to form the central body portion  400  of an occlusion shell support structure  310  of a septal occluder  320 .  
         [0000]     Modifications of the Multi-Strand Bundles  
         [0042]     The invention contemplates modifying the multi-strand bundles  41  which form an arm or arms  300  and/or the central body portion  400  of an intracardiac occluder in order to improve articulation of the intracardiac occluder  320  in the intracardiac defect. Enhanced conformability, increased flexibility and reduced bending stiffness of the occlusion shells  302 ,  304  allows the septal occluder  320  according to the invention to conform to the tissue contacted by the occluder  320 , thereby reducing trauma to the tissue, and increasing the defect closure rate. In order to accomplish these objectives, the multi-strand bundles  41  may be modified according to illustrative embodiments of the invention as described below.  
         [0043]     Referring again to  FIG. 3  and  FIG. 4 , in one embodiment according to the invention, a flexural point  51  can be achieved by introducing a part  42  amongst the strands  40  by separating one or more strands  40  from the other strands  40  in the multi-strand bundle  41  to form a gap  46 . For example, at least one strand  40  is parted from the remaining strand or strands  40  to form the gap  46 , the gap  46  being defined by the parted strands. In an alternative embodiment, as shown in  FIG. 5 , a flexural point  51  in the form of gap  46  may also be achieved by forming the gap  46  by creating a part  42  between the multi-strand bundles  41  forming the cable  49 . For example, at least one multi-strand bundle  41  is parted from the remaining multi-strand bundle or bundles  41  to form the gap  46 .  
         [0044]     According to one embodiment of the invention, a flexural point  51  is disposed on at least one arm  300  of an occlusion shell  302 ,  304 . In another embodiment, a flexural point  51  may be disposed on more than one arm  300  of an occlusion shell  302 ,  304 . The invention further contemplates an arm  300  with more than one flexural point  51 . For example, an arm  300  may have one, two, three, four, five or more flexural points  51 . In one embodiment, a flexural point  51  occurs near or at the tip  380  of the arm  300 , while in another embodiment, a flexural point does not occur at the tip  380  of the arm  300 . In another embodiment, the flexural point  51  may occur anywhere along the length of the arm  300 . In one embodiment, the flexural point  51  is a gap  46 .  
         [0045]      FIG. 7  depicts a top view of an exemplary occlusion shell  302  of an exemplary intracardiac occluder  320  with arms  300  constructed of the multi-strand bundle shown in  FIG. 3 , according to an illustrative embodiment of the invention. According to the illustrative embodiment, the occlusion shell  302 ,  304 , for example the proximal occlusion shell  302 , has four arms  300 ,  300 ′,  300 ″,  300 ′″. In one embodiment, at least one arm  300  is made of a multi-strand bundle  41  with the at least one arm  300  having a gap  46  between the strands  40  of the multi-strand bundle  41  forming a flexural point  51 . In another embodiment, all arms  300  of the occlusion shell  302 ,  304  are made of multi-strand bundles  41 , with each arm having a gap  46  between the strands  40  of the multi-strand bundle  41  forming a flexural point  51 . The flexural point  51  enhances flexibility of the arm  300  by decreasing the arm&#39;s  300  resistance. The flexural point  51  also increases the arm&#39;s  300  surface area, which reduces trauma to the surrounding tissue and improves stability of the septal occluder  320  in the defect. These features improve the ability of the septal occluder  320  to seal the defect in which the septal occluder  320  is inserted.  
         [0046]     According to another embodiment of the invention, flexural points  51  may also be created through the use of loops, generally,  122 . For example,  FIG. 8A  depicts a top view of a portion of an arm  300  of a septal occluder  320  made from a multi-strand bundle  41  forming a single loop  122  according to the invention.  FIG. 8B  depicts a side view of the single loop  122  shown in  FIG. 8A . The single loop  122  forms a flexural point  51  along the length of the arm  300 .  
         [0047]      FIG. 9A  depicts a top view of an occlusion shell  302  of an illustrative intracardiac occluder  320  with arms  300  made from multi-strand bundles  41  with loops  122  as shown in  FIG. 8A , while  FIG. 9B  depicts a side view of the view of the exemplary occlusion shell  302  and illustrative intracardiac occluder  320  shown in  FIG. 9A , where the arms  300  of the occlusion shell  302 ,  304  are made from multi-strand bundles  41  with loops  122  as shown in  FIG. 8A , according to an illustrative embodiment of the invention. As shown in  FIG. 9A , the support structure  310 , for example, the proximal support structure  314 , may have one or more arms  300  as previously discussed. In one embodiment, at least one arm  300  of the support structure  314  has a loop  122 , whereas in another embodiment, more than one arm  300  of the support structure  314  has a loop  122 . In another embodiment, at least one arm  300  has more than one loop  122 . As shown in  FIGS. 9A and 9B , when more than one loop  122  is present on one arm  300 , in one embodiment the loops  122  are spaced along the length of the arm  300 , thus creating a flexural point  51  at each point on the arm  300  where a loop  122  is present. In one embodiment, each loop  122  has the same diameter as each other loop  122  on the arm  120 , whereas in another embodiment, at least one loop  122  on an arm  300  has a different diameter than a second loop  122  on the arm  300  as discussed below.  
         [0048]     Flexural points  51  may also be created through the use of a coil  123 , according to an illustrative embodiment of the invention. In one embodiment, a coil  123  as used herein is defined as two or more consecutive loops  122  on the strand  40  that forms the arm  300  of an occlusion shell. Alternatively, in another embodiment, a coil  123  as used herein defines two or more consecutive loops on a multi-strand bundle  41  making up a cable  49 . For example, a coil  123  can include two, three, four, five or more loops  122 .  
         [0049]      FIG. 10A  depicts a side view of a portion of an arm of a septal occluder  320  made from a multi-strand bundle  41  having multiple consecutive loops  122  at the same point on the length of the arm  300  forming a coil  123 , while  FIG. 10B  depicts a top view of the portion of the arm  300  shown in  FIG. 10A , according to an illustrative embodiment of the invention. In one embodiment, multiple consecutive loops  122 ,  122 ′,  122 ″ forming a coil  123  are present at one flexural point  51  on an arm  300 . In one embodiment, the loops  122  forming the coil  123  are parallel or substantially parallel to each other, while being perpendicular to the length of the arm  300 , while in another embodiment, the loops  122  forming the coil  123  are parallel or substantially parallel to each other, and are also parallel or substantially parallel to the length of the arm  300 . In another embodiment, the loops  122  present at the same flexural point  51  may be of the same diameter as shown in  FIG. 10A , or they may be of different diameters as discussed below in relation to  FIGS. 12A  and B.  
         [0050]     With continued reference to  FIGS. 10A  and B, in a further embodiment, an arm  300  has more than one flexural point  51  with multiple consecutive loops  122 ,  122 ′,  122 ″ forming a coil  123  at each flexural point  51  along the length of the arm  300 . In yet another embodiment, an arm has multiple flexural points  51 , where at least one flexural point has a single loop  122 , as shown, for example, in  FIG. 8A , and at least one other flexural point  51  has multiple loops  122 ,  122 ′,  122 ″ forming a coil  123 , as shown, for example, in  FIG. 10A . In another embodiment, the central body portion  400 , which joins at least two occlusion shells  302 ,  304 , may also have multiple loops  122 ,  122 ′,  122 ″ present at one flexural point  51  on the central body portion  400  forming a coil  123 . In another embodiment, each loop  122  forming a coil  123  at one flexural point  51  may be of the same or different diameter, as discussed below in relation to  FIGS. 12A  and B.  
         [0051]     Referring again to  FIG. 2 , in another embodiment, a single strand or multi-strand bundle includes a helical coil  401 . The helical coil  401  is formed by rotating the strand or bundle in a constantly changing plane around a central axis and includes multiple loops  122 , with each loop  122  being at a different point along the central body portion  400 . For example, in one embodiment, the helical coil  401  has two, three, four, five, six, seven, eight, nine, ten or more loops  122 . In one embodiment, according to the invention, the helical coil  401  can be used to connect two occlusion shells  302 ,  304  as shown in  FIG. 2 . Additionally, all or a portion of the length of the central body portion  400  includes the helical coil  401 . The helical coil  401 , for example, is a compression coil or alternatively, a tension coil.  
         [0052]     According to yet another embodiment of the invention, as shown in  FIG. 2 , one or more arms  300  include a helical coil  401  for at least a portion of the length of the arm  300 . The helical coil  401  is formed by rotating the strand or bundle in a constantly changing plane around a central axis and includes multiple loops  122 , with each loop  122  being at a different point along the arm  300 . For example, in one embodiment, each loop  122  of the helical coil  401  creates a flexural point  51  along the length of the arm  300 . In one embodiment the helical coil  401  along the length of the arm  401  is a compression coil, or alternatively, a tension coil.  
         [0053]      FIG. 11A  depicts a side view of a portion of an arm  300  of a septal occluder  320  made from a multi-strand bundle  41  including loops  122  of varying diameters along the length of the bundle  41  forming the arm  300 , while  FIG. 11B  depicts a top plan view of the portion of the arm shown in  FIG. 11A , according to an illustrative embodiment of the invention. In one embodiment, when the arm  300  includes multiple loops  122 , for example, loops  122 ,  122 ′,  122 ″, the diameter of the loops  122  can vary.  
         [0054]     Alternatively, referring again to  FIG. 2 , the central body portion  400  may also include loops  122  of varying diameter along the length of the central body portion  400 . For example,  FIG. 2  depicts an embodiment wherein the central body portion  400  includes loops  122  of varying diameter, i.e, loops  122  of a smaller diameter in region  306  are positioned between loops  122  of a larger diameter in region  308 . Loops  122  varying in diameter may be present on an individual strand  40 , on a multi-strand bundle  41 , or on a cable  49  of the central body portion  400 , and/or on one or more arms  300  of an occlusion shell, for example, the proximal occlusion shell  302 . Also, loops  122  varying in diameter may be present at the same flexural point  51  on the arm  300  or the central body portion  400 . The variation in diameter of the loops  122  enhances the flexibility of the intracardiac occluder, including the arms  300  and the central body portion  400 .  
         [0055]     In addition, when a loop or loops  122  are present on an arm  300  or on the central body portion  400 , a safety wire (not shown) can be attached to the arm  300  or the central body portion  400  to prevent overextension of the loop or loops  122 . In one embodiment, the safety wire runs through the inner lumen of a coil  123  and is attached to the first loop and last loop  122  of a coil  123  positioned on an arm  300  or central body portion  400 . Alternatively, the safety wire is attached to the first loop and last loop  122  of a coil  123 , and runs along the outer surface  124  of the coil  123 . The safety wire may be made from a suitable metal, such as stainless steel, nitinol, or MP35N, or it may be made from a polymer or a bioresorbable material.  
         [0056]      FIG. 12A  depicts a side view of a portion of an arm  300  of a septal occluder  320  made from a multi-strand bundle  41  comprising a plurality of loops  122  of varying diameters forming a coil  123  along the length of the bundle  41 , while  FIG. 12B  depicts a top plan view of the arm  300  having loops  122  forming a coil  123  as illustrated in  FIG. 12A . According to this illustrative embodiment of the invention, the loops  122  are parallel to each other while being perpendicular or substantially perpendicular to the length of the arm  300  or central body portion  400  on which the loops  122  are disposed. The loops  122 ,  122 ′,  122 ″, and  122 ′″ in this embodiment all vary in diameter compared to one another. In yet another embodiment, at least two loops  122  of differing diameters are parallel to each other, but are perpendicular or substantially perpendicular to the length of the arm  300  or central body portion  400  on which the loops  122  are disposed. In yet another embodiment, at least two loops  122  of differing diameters are parallel to each other, and are parallel or substantially parallel to the length of the arm  300  or the central body portion  400  on which the loops  122  are disposed.  
         [0057]     According to a further embodiment of the invention, each loop  122  need not be of a different diameter than another loop  122 . For example, an arm  300  or central body portion  400  may have two or more loops  122  of one diameter, as well as a loop or loops  122  of a second differing diameter. According to one embodiment of the invention, at least two loops  122  of the same diameter are parallel to each other, but are perpendicular or substantially perpendicular to the length of the arm  300  or central body portion  400  on which the loops  122  are disposed. In a further embodiment, a safety wire runs through the inner lumen of the loops  122  of a coil  123  and is attached to the first and last loop  122  of the coil  123  positioned on an arm  300  or central body portion  400 . Alternatively, the safety wire is attached to the first and last loop  122  of a coil  123 , and runs along the outer surface  124  of the coil  123 . The safety wire may be made from a suitable metal, such as stainless steel, nitinol, or MP35N, or it may be made from a polymer or a bioresorbable material.  
         [0058]     According to the invention, varied flexibility and conformability of a septal occluder can also be achieved by varying the shape of the strands in a multi-strand bundle.  FIG. 13  depicts a portion of an arm  300  of a septal occluder made from a multi-strand bundle  41  according to an illustrative embodiment of the invention, while  FIGS. 14-17  depict various cross-sectional views of the strands  40  that make up the arm  300  depicted in  FIG. 13 , according to illustrative embodiments of the invention. The strands  40  forming the multi-strand bundles  41  of the arms  300  may include a non-circular cross-section. For example, as illustrated in  FIGS. 15 and 17 , the cross-section of the strands  40  is triangular. A triangular strand cross-section produces a higher point pressure along the edge of the strand formed by the apices of the triangle. Conversely, the flat side of a triangular strand may aid in minimizing trauma to the cardiac tissues by eliminating pressure points. In another embodiment, the strands  40  may have a rectangular or ribbon-like cross-section as shown in  FIG. 14 , while in yet another embodiment, shown in  FIG. 16 , the cross-section of the strands  40  is hexagonal. Additionally, the cross section of a strand  40  may be circular, or alternatively, any non-circular geometric shape. For example, an elliptical, rectangular, rhomboidal, trapezoidal, or any other polygonal or non-circular geometric shaped cross-section may be used.  
         [0059]     Furthermore, in one embodiment, at least one strand  40  of the multi-strand bundle  41  forming an arm  300  of an septal occluder  320  comprises a circular cross-section. For instance, in one embodiment, the cross-section of one or more strands  40  is circular. In another embodiment (not shown), the cross-section of one strand  40  is circular while the cross-section of one or more strands  40  is triangular. Alternatively, the invention also features mixing two or more non-circular strands  40  to form multi-strand bundles  41  (not shown). For example, in one embodiment (not shown), the cross-section of one or more strands  40  is circular, while the cross-section of one or more strands  40  is triangular, and the cross-section of one or more strands  40  is octagonal. Optionally, in another embodiment, the cross-section of one or more strands  40  is square, while the cross-section of one or more strands  40  is triangular, and the cross-section of one or more strands  40  is pentagonal.  
         [0060]     With continued references to  FIGS. 13-17 , the invention contemplates that the support structure  310  of an intracardiac occluder  320 , such as an arm or arms  300  and/or the central body portion  400  is comprised of any of the embodiments of multi-strand bundles of non-circular or circular cross-section as described above. For example, in one embodiment, an occlusion shell  312 ,  314  has at least one arm  300  comprising a strand with a non-circular cross-section. An occlusion shell  312 ,  314  may have two or more arms  300  comprising a strand of non-circular cross-section.  
         [0061]     According to the invention, varied flexibility and conformability of a septal occluder can also be achieved by varying the diameter or thickness of the strands  40  in a multi-strand bundle  41 . For example, in one embodiment (not shown), the diameter of at least one strand  40  is larger than the diameter of another strand  40 , or in other words, at least one strand  40  is thicker than another strand  40 . There may be as many diameters or thicknesses of strands  40  as there are strands  40  in a bundle  41 . Multi-strand bundles  41  made from strands  40  of varying thicknesses or diameters may be used to create an arm or arms  300  and/or the central body portion  400  of an intracardiac occluder  320 .  
         [0062]     According to the invention, varied flexibility and conformability of a septal occluder can also be achieved by varying the length of strands  40  in a multi-strand bundle  41 . For example, in one embodiment (not shown), at least one strand  40  has a greater length than another strand  40  in a bundle  41 . However, there may be one, two, three, four, five, six or more lengths represented in a multi-strand bundle  41  of strands  40 . It is possible to have as many representative lengths of strands  40  as there are strands  40  in that multi-strand bundle  41 . For example, in one embodiment, a strand has a first length, another strand has a second length, and yet another strand has a third length. In yet another embodiment, each strand  40  differs in length from every other strand in the multi-strand bundle  41 . While the length of strands  40  in a bundle  41  may differ, the bundle  41  may also include strands  40  of the same length. For example, in one embodiment, at least one strand  40  differs in length from at least one other strand  40 , and at least one strand  40  is equal in length to at least one other strand  40 . Multi-strand bundles  41  of strands  40  may be used to create an arm or arms  300  and/or the central body portion of an intracardiac occluder  320 .  
         [0063]     Varied flexibility and conformability of a septal occluder can also be achieved by varying the pitch of the strands in a multi-strand bundle.  FIGS. 18-20  each depict a portion of an arm  300  of a septal occluder  320  made of a multi-strand bundle  41 , wherein the pitch of the component strands  40  in each multi-strand bundle  41  differs from the pitch of the strands  40  in the other exemplary multi-strand bundles  41  shown, according to illustrative embodiments of the invention. According to the illustrative embodiments, the pitch of the strands  40  in a multi-strand bundle  41 , or the pitch of the multi-strand bundle  41  in a cable  49  may be altered to increase or decrease its flexibility. As the angle θ  601  defining the pitch of the strands  40  in a multi-strand bundle  41 , or the pitch of the multi-strand bundle in a cable  49  increases toward 90°, the bending stiffness of the bundle  41  or cable  49  decreases and the flexibility increases. As the angle θ  601  defining the pitch of the strands  40  in a multi-strand bundle  41 , or the pitch of the multi-strand bundle in a cable  49  decreases toward 0°, the bending stiffness of the bundle  41  or cable  49  increases and the flexibility decreases.  
         [0064]     Multi-strand bundles  41  or portions of multi-strand bundles  41  annealed at various temperatures may also be used in the arm or arms  300  and/or the central body portion  400  of the intracardiac occluder  320  according to the invention in order to affect the flexibility and conformability of the septal occluder. For example, in a multi-strand bundle  41 , at least one strand  40  is annealed at a different temperature than at least one other strand  40  in the multi-strand bundle  41 . In a further embodiment, one or more strands  40  in a multi-strand bundle  41  is annealed at a different temperature than at least one other strand  40  in the bundle  41 . In a further embodiment, a bundle  41  may have one or more strands  40  subjected to a first annealing temperature, one or more strands  40  subjected to a second annealing temperature, and one or more strands  40  subjected to a third annealing temperature. In a further embodiment, each strand  40  has a different annealing temperature than every other strand  40  in the bundle  41 . For example, there may be as many representative annealing temperatures as there are strands  40  in a given multi-strand bundle  41 .  
         [0065]     The advantage of varying the annealing temperatures of the various strands  40  is that different temperatures impart different mechanical properties to the multi-strand bundle  41 . For example, in one embodiment stiffer strands  40  are positioned in the core of a multi-strand bundle and more pliable strands  40  are positioned on the outer segments of a multi-strand bundle. In another embodiment, it is beneficial to interweave softer strands  40  together, while in another embodiment, weaving stiffer strands  40  together is advantageous. For example, in one embodiment, the strands  40  of the multi-strand bundle  41  are made of nitinol, with at least one strand  40  being heat treated to impart enhanced flexibility to the strand  40 , while at least one other strand  40  is heat treated to impart greater stiffness to that strand  40 .  
         [0066]     In another embodiment according to the invention, strands that form arms  300  of the septal occluder  320  may be subjected to one or more annealing temperatures along their lengths.  
         [0067]     For example, a strand  40  is annealed at a higher temperature at the center, but annealed at a lower temperature towards the ends of the strand. Multi-strand bundles  41  made from strands annealed at different temperatures at different points along the strands&#39; lengths produces multi-strand bundles  41  that have more pliable regions along the lengthwise axis of the multi-strand bundle  41  intermixed with stiffer regions along the length of the multi-strand bundle  41 . This aids in reducing trauma by permitting flexion of the multi-strand bundles  41  at the more pliable regions along the length of the bundles  41 . In one embodiment of the invention, an occlusion shell  302  of an intracardiac occluder  320  comprises an arm  300  comprising a multi-strand bundle  41  where at least one strand  40  in the arm  300  is annealed at a different temperature than at least one other strand  40  in the same arm  300 . In a further embodiment, an occlusion shell  302  of an intracardiac occluder  320  comprises one or more arms  300  comprising a multi-strand wire bundle  41  and in each arm  300 , at least one strand  40  in the arm  300  was annealed at a different temperature than at least one other strand  40  in the same arm  300 . In yet another embodiment, an occlusion shell  302  comprises one or more arms  300  comprising a multi-strand bundle  41  wherein at least one strand  40  in the multi-strand bundle has been subjected to two or more annealing temperatures along its length. In another embodiment of the invention, the central body portion  400  can comprise a multi-strand bundle  41  where at least one strand  40  in the central body portion  400  was annealed at a different temperature than at least one other strand  40  in the central body portion  400 . In yet another embodiment, an arm or arms  300  and/or the central body portion  400  of an intracardiac occluder  320  may comprise any of the multi-strand bundles with strands  40  annealed at temperatures as described above.  
         [0068]     While many of the modifications discussed above have been discussed in the context of the arms  300  of an occlusion shell support structure  314 , these variations are equally applicable to any individual strand  40 , multi-strand bundle  41 , or cable  49  comprising the central body portion  400  of the intracardiac occluder  320  according to the invention. Furthermore, multi-strand bundles  41  of the invention may comprise multiple modifications within the same bundle. For example, a multi-strand bundle  41  forming an arm or arms  300  and/or the central body portion  400  of a flexible intracardiac occluder  320  may include any one or more of the following modifications including, but not limited to varying the number of strands  40  in a multi-strand bundle  41 , varying the number of multi-strand bundles  41  in a cable  49 , and varying the cross-sectional geometry of the individual strands  40 , varying the diameter or thickness of individual strands  40 , varying the length of individual strands  40 , varying the annealing temperature of individual strands  40 , varying the pitch of the strands  40  in a multi-strand bundle  41 , varying the diameter of loops  122 , and adding gaps  46  or loops  122 , including coils  123  or helical coils  401  to a multi-strand bundle.  
         [0000]     Deployment of a Intracardiac Occluder  
         [0069]      FIGS. 21A-21E  depict multiple steps used to insert a septal occluder in a defect in a patient&#39;s heart according to an illustrative embodiment of the invention. The intracardiac occluder  320  according to the invention described above is delivered percutaneously and transvascularly via a catheter  20  and guided to a predetermined location, for example, to a PFO  14 .  
         [0070]     As shown in  FIG. 21A , in one embodiment of the invention, a collapsed septal occluder  320  is inserted into a catheter  20  with the distal occlusion shell  304  collapsed and positioned distally to the proximal occlusion shell  302 . The catheter  20 , with the collapsed intracardiac occluder  320  contained in a distal portion thereof is inserted into a blood vessel of a patient and is navigated through the patient&#39;s blood vessels into the heart and, for example, crosses the intracardiac defect  14 .  
         [0071]     As shown in  FIG. 21B , according to one embodiment of the invention, the intracardiac occluder  320  is deployed beyond the distal end of the catheter  20  to cause the distal occlusion shell  304  to exit the distal end of the catheter  20 . Such deployment can be accomplished either by advancing the intracardiac occluder  320  within the catheter by means of, for example, advancing a positioning wire  28  joined to the intracardiac occluder  320  distally while holding the catheter  20  in place, or by retracting the catheter  20  while proximally holding the intracardiac occluder  320  in place with the positioning wire  28 . Once the distal occlusion shell  304  has been advanced beyond the distal end of the catheter  20 , the occlusion shell  304  will automatically and resiliently open to its expanded configuration.  
         [0072]     As shown in  FIG. 21C , the catheter  20  and intracardiac occluder  320 , in one embodiment, are then retracted to seat the distal occlusion shell  304  against the distal wall  25  of the defect  14  to occlude the defect  14 . As shown in  FIG. 21D , in one embodiment, the catheter sheath  20  is further withdrawn proximally to allow the proximal occlusion shell  302  to be deployed from the distal end of the catheter  20 . Once deployed, the proximal occlusion shell  302  opens automatically and resiliently in same manner as the distal occlusion shell  304 .  
         [0073]     As shown in  FIG. 21E , upon deployment, the proximal occlusion shell  302  lies against the proximal wall  26  of the intracardiac defect  14  thereby occlusion the defect  14  on the proximal side. The catheter  20  and position wire  28  are then withdrawn from the patient leaving the deployed intracardiac occluder  320  with the occlusion shells  302 ,  304  positioned on each side of the intracardiac defect  14 . Because the occlusion shells  302 ,  304  are free to move relative to each other, being able to rotate about the axis of the central body portion  400 , the intracardiac occluder  320  can be used in applications in which it is desirable that the occluder elements are not directly opposed to one another. For example, such an intracardiac occluder  320  can be used to correct flap-like or tunnel-like defects in the atrial septum, other intracardiac defects.  
         [0074]     Variations, modifications, and other implementations of what is described herein will occur to those of ordinary skill in the art without departing from the spirit and the scope of the invention as claimed. Accordingly, the invention is to be defined not by the preceding illustrative description, but instead by the spirit and scope of the following claims.