Abstract:
The invention generally relates to devices and methods for treating cardiac tissue, including percutaneous closure of cardiac openings such as a patent foramen ovale (PFO) and obliteration of the cardiac cul-de-sacs. The invention includes a device having at least one elongated member. The elongated member has a first material and a second material interwoven with at least a portion of the first material. The second material is capable of transferring energy to tissue in need of treatment.

Description:
RELATED APPLICATIONS  
       [0001]     This application claims benefit of and priority to U.S. provisional application 60/714,374, filed Sep. 6, 2005 and U.S. provisional application 60/734,558, filed Nov. 8, 2005, the disclosures of each are incorporated by reference herein. 
     
    
     TECHNICAL FIELD  
       [0002]     The invention generally relates to devices and related methods for treating cardiac tissue. More particularly, the invention features devices and methods of using devices comprising at least two different interwoven materials wherein at least one of the materials is an energy transferring material.  
       BACKGROUND  
       [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 interatrial septum, while the ventricles are separated by the interventricular 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 inappropriately flow there through. 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 septal deformities result from the incomplete formation of the septum, or muscular wall, between the chambers of the heart and can cause significant morbidity.  
         [0005]     One such septal deformity or defect, a patent foramen ovale (PFO), is a persistent, one-way, usually tunnel shaped, 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 problematic for patients who are prone to forming venous thrombi, such as those with deep vein thrombosis or clotting abnormalities. Patients with a PFO may be prone to a cerebrovascular accident known as a stroke.  
         [0006]     Moreover, certain patients are prone to atrial arrhythmias (i.e., abnormal heart rhythms which can cause the heart to pump less effectively). In a common such abnormality, atrial fibrillation, the two upper chambers of the heart (i.e., the left atria and the right atria), quiver instead of beating in coordination with other cardiac chambers. Because the atria do not beat and empty cleanly during atrial fibrillation, blood can stagnate on the walls and form clots that can then pass through the heart and into the brain, causing a stroke or a transient ischemic attack. These clots typically form in a cul-de-sac in the heart called the left atrial appendage due to its tendency to have low or stagnant flow.  
         [0007]     Nonsurgical (i.e., percutaneous) tissue treatment and closure of a patent foramen ovale and similar cardiac openings, such as an atrial septal defect or a ventricular septal defect, as well as obliteration of a left atrial appendage, can be achieved using a variety of mechanical devices that are introduced via an artery into a large peripheral vessel, e.g., the femoral vein. These devices typically consist of a structural framework with a scaffold material attached thereto. Currently available devices, however, are often complex to manufacture, are inconsistent in performance, require a technically complex implantation procedure, lack anatomic conformability, and lead to complications (e.g., thrombus formation, chronic inflammation, residual leaks, perforations, device fractures, and conduction system disturbances).  
         [0008]     Improved devices, systems, and related methods for treating cardiac tissue and/or closing cardiac openings, such as, for example, a patent foramen ovale, and for obliterating cardiac cul-de-sacs, such as, for example, a left atrial appendage, are therefore needed.  
       SUMMARY OF THE INVENTION  
       [0009]     The present invention provides devices and related methods for treating cardiac tissue. In one aspect, the invention features a device for treating cardiac tissue. The device comprises a first sheath comprising a distal end, a proximal end and a lumen extending between the distal end and proximal end of the sheath. At least one elongated member is slidably disposed within the lumen of the sheath, and the elongated member is comprised of a first material and a second material. The first material is substantially non-conductive, while the second material is an energy transferring material. At least a portion of the second material is interwoven with at least a portion of the first material.  
         [0010]     In one embodiment, the second material comprises copper, gold, metal, platinum, silver, iron, lithium, cobalt, nickel, chromium or a combination thereof, while in another embodiment the second material comprises an energy transferring ceramic or glass material. In another embodiment according to this aspect of the invention, the energy to be transferred includes electromagnetic energy, such as, for example, microwave, infrared, visible light waves, ultraviolet light waves, x-ray, gamma ray, or cosmic ray. In a further embodiment, the electromagnetic energy comprises radio frequency energy.  
         [0011]     According to one embodiment, at least a portion of the elongated member comprises a straight wire or bristles, while in another embodiment, the second material is disposed on a filament. In another embodiment, at least a portion of the elongated member comprises a sleeve, and in an additional embodiment, at least a portion of the elongated member comprises a braid, coil, knot, spiral or zigzag. Alternatively, in yet another embodiment, at least a portion of the elongated member comprises a tube or a cone. In further embodiments, the elongated member comprises a lumen, and a negative force such as a negative pressure or vacuum is applied to the lumen of the elongated member. In other embodiments of the invention, a negative force is applied to the lumen of the sheath, while in a further embodiment the sheath is joined to a vacuum source.  
         [0012]     In one embodiment, the device comprises a second sheath comprising a lumen for slidably receiving the first sheath. In additional embodiments, a negative pressure such as a vacuum is applied to the second sheath. In another embodiment, the second sheath is joined to a vacuum source. In a further embodiment, the second sheath is axially disposed within the lumen of the first sheath. In an even further embodiment, the elongated member is slidably receivable within the second sheath, while in another embodiment, the second sheath is axially disposed within a lumen of the elongated member.  
         [0013]     In another embodiment of the invention, the elongated member is operatively joined to an actuator. In one embodiment, movement of the actuator causes movement of the elongated member in an axial direction in relation to the sheath. In other embodiments, the sheath is operatively joined to an actuator.  
         [0014]     In another embodiment, the elongated member comprises a distal end and a proximal end. In a further embodiment, the elongated member comprises a wire. The wire comprises an open ended loop, the loop comprising a hairpin turn, for example, at the distal end of the elongated member and two free ends at the proximal end of the elongated member. According to one embodiment, at least one free end of the wire is affixed to an actuator. In another embodiment, movement of the actuator in a distal direction unfurls a portion of the elongated member from the lumen of the sheath moving the distal end of the elongated member even further in the distal direction. In a further embodiment, movement of the elongated member in the distal direction places at least a portion of the second material in contact with the cardiac tissue in need of treatment. In yet a further embodiment, movement of the actuator in a proximal direction retracts a portion of the elongated member inside the lumen of the sheath and moves the distal end of the elongated member in the proximal direction.  
         [0015]     In another embodiment of the invention, the elongated member comprises a sleeve comprising an exterior surface and an interior surface. In one embodiment, the exterior surface of the sleeve is affixed to an actuator. In a particular embodiment, the sleeve comprises a first position in which a portion of the elongated member comprising the second material interwoven with the first material is located on the interior surface of the sleeve. In a further embodiment, movement of the actuator in a proximal direction transitions the sleeve into a second position wherein at least a portion the interwoven second material is located on the exterior surface of the sleeve.  
         [0016]     Another embodiment of the invention features the interior surface of the sleeve affixed to an actuator. According to one embodiment, the sleeve comprises a first position in which the portion of the elongated member comprising the second material interwoven with the first material is located on the exterior surface of the sleeve. In another embodiment, movement of the actuator in a proximal direction transitions the sleeve into a second position wherein at least a portion the interwoven second material is located on the interior surface of the sleeve.  
         [0017]     A further aspect of the invention includes a device for treating cardiac tissue. The device comprises at least one elongated member including a first material and a second material. The first material is a substantially non-conductive material, while the second material is an energy transferring material and at least a portion of the second material is interwoven with at least a portion of the first material. In one embodiment, the second material comprises copper, gold, metal, platinum, silver, iron, lithium, cobalt, nickel, chromium, or a combination thereof. In another embodiment, the second material comprises a glass or ceramic material.  
         [0018]     Another aspect of the invention features a method for treating cardiac tissue. The method comprises the step of advancing a device to a position adjacent to cardiac tissue that is in need of treatment. The device includes a first sheath and at least one elongated member slidably disposed within a lumen of the sheath, the elongated member comprising a first material and a second material. The first material is substantially a non-conductive material. At least a portion of the second material is interwoven with at least a portion of the first material. The second material is capable of transferring energy from an energy source. The method further comprises the steps of advancing the elongated member through the lumen of the sheath wherein at least a portion of the second material comes into contact with the cardiac tissue in need of treatment, and applying the energy source to the second material to transfer energy to the cardiac tissue.  
         [0019]     In one embodiment of this method of the invention, the elongated member comprises a wire, having an open ended loop. The loop comprises a hairpin turn at a distal end of the elongated member and two free ends at a proximal end of the elongated member. In another embodiment, at least one free end of the wire open-ended loop is operatively joined to an actuator. In a particular embodiment, movement of the actuator in the distal direction unfurls a portion of the elongated member from the lumen of the sheath, thereby moving the distal end of the elongated member in the distal direction. In an additional embodiment, the method further comprises the step of moving the actuator in the distal direction to place at least a portion of the second material in contact with the cardiac tissue in need of treatment. In a further embodiment, movement of the actuator in the proximal direction retracts a portion of the elongated member within the lumen of the sheath and moves the distal end of the elongated member in the proximal direction.  
         [0020]     According to one embodiment, energy comprises microwave, infrared, visible light waves, ultraviolet light waves, x-ray, gamma ray, or cosmic ray. In another embodiment, the energy comprises radio frequency energy.  
         [0021]     A further embodiment according to this aspect of the method of the invention comprises the step of attaching a vacuum source in communication with the lumen of the first sheath or the second sheath. The method of the invention can further comprise the step of applying a negative pressure to the lumen of the first sheath or the second sheath. In a further embodiment, the negative pressure is provided by a vacuum generating source, e.g., a pump.  
         [0022]     In an additional embodiment, the device of the invention comprises a second sheath having a lumen wherein the first sheath is axially disposed within the second sheath. In one embodiment, the method comprises the step of applying a negative force, e.g., negative pressure to the lumen of the second sheath. In a further embodiment, the device comprises a second sheath having a lumen and the second sheath is axially disposed within the lumen of the first sheath. In a further embodiment, the elongated member is slidably receivable in the second sheath. Alternatively, the elongated member is fixed and the sheath is slideably moveable over the elongated member.  
         [0023]     A further aspect of the invention features a method for treating cardiac tissue and comprises the step of advancing a device to a position adjacent to cardiac tissue in need of treatment. The device includes at least one elongated member comprising a first material and a second material. The first material is a substantially non-conductive material. The second material is an energy transferring material. At least a portion of the second material is interwoven with at least a portion of the first material, and the second material is capable of transferring energy from an energy source. This aspect also includes the steps of contacting at least a portion of the second material with the cardiac tissue in need of treatment, and transferring energy to the cardiac tissue in need of treatment. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0024]     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.  
         [0025]      FIG. 1A  is a schematic side view of a device for treating cardiac tissue, according to an illustrative embodiment of the invention.  
         [0026]      FIG. 1B  is a schematic side view of a device for treating cardiac tissue including a vacuum source and vacuum cone according to another embodiment of the invention.  
         [0027]      FIG. 1C  is a schematic view of a cross section in  FIG. 1A  taken at  1 B- 1 B.  
         [0028]      FIG. 2A  is a partial cross-sectional view of a distal end of a device for treating cardiac tissue, the device comprising an elongated member retracted within a lumen of the sheath of the device, according to an illustrative embodiment of the invention.  
         [0029]      FIG. 2B  is a partial cross-sectional view of the distal end of a device for treating cardiac tissue as illustrated in  FIG. 2A , with the elongated member unfurled beyond the distal end of the sheath, according to an illustrative embodiment of the invention.  
         [0030]      FIG. 2C  is a partial cross-sectional view of the distal end of the device for treating cardiac tissue as illustrated in  FIG. 2A , with the elongated member extended distally beyond the lumen of the sheath and in proximity to tissue in need of treatment, according to an illustrative embodiment of the invention.  
         [0031]      FIG. 2D  is a schematic view of a cross section in  FIG. 2C  taken at  2 D- 2 D.  
         [0032]      FIG. 3A  is a partial cross-sectional view of a distal end and proximal end of a device for treating cardiac tissue, the device comprising an elongated member in the form of a sleeve and a cable for manipulating the elongated member, according to an illustrative embodiment of the invention.  
         [0033]      FIG. 3B  is a schematic view of a cross section in  FIG. 3A  taken at  3 B- 3 B.  
         [0034]      FIG. 3C  is a partial cross-sectional view of the device illustrated in  FIG. 3A  after the elongated member is manipulated in the direction indicated by direction arrow  112  in  FIG. 3A , according to an illustrative embodiment of the invention.  
         [0035]      FIG. 3D  is a schematic view of a cross section in  FIG. 3C  taken at  3 D- 3 D.  
         [0036]      FIG. 4  is a schematic side view of a distal end of a device for treating cardiac tissue, the device comprising a first sheath, an elongated member and a second sheath surrounding the first sheath, according to an illustrative embodiment of the invention.  
         [0037]      FIG. 5  is a schematic side view of a distal end of a device for treating cardiac tissue, the device comprising a first sheath, an elongated member and a second sheath within the lumen of the first sheath, according to an illustrative embodiment of the invention.  
         [0038]      FIG. 6  is a schematic side view of a distal end of a device for treating cardiac tissue, the device comprising an elongated member having a first material and a second material interwoven with a portion of the first material, according to an illustrative embodiment of the invention. 
     
    
     DESCRIPTION OF THE INVENTION  
       [0039]     The present invention features devices and related methods for treating cardiac tissue. The cardiac tissue in need of treatment includes, for example, cardiac septa and tissue of the left and right atria. The invention is also useful in closing various cardiac openings, for example, a patent foramen ovale (PFO), an atrial septal defect, or a ventricular septal defect.  
         [0040]     The present invention features systems and related methods for closing cardiac openings, such as, for example, a PFO, described below. Throughout the description, the terms proximal and distal refer to the position of elements relative to the operator of the exemplary apparatus. Proximal is that portion of the device closer to the operator and distal is that portion of the device further away from the operator.  
         [0041]      FIG. 1A  is a schematic side view of an exemplary device  2  for treating cardiac tissue  18 , the device  2  comprising a sheath  4  having a distal end  6 , a proximal end  8 , and a lumen  10  that extends between the distal end  6  and proximal end  8  of the sheath  4 , a handle  30 , and an actuator  32  on the handle  30 . The exemplary sheath  4  extends from a proximal end  8  at the handle  30  to a distal end  6 . In one embodiment, shown in  FIG. 1A , the device  2  further features at least one elongated member  12  slidably disposed within the lumen  10  of the sheath  4 .  
         [0042]      FIG. 1B  illustrates yet another embodiment of the device  2  including a vacuum source  102 . This embodiment may feature a cone  106  disposed at the distal end  6  of the sheath  4 .  
         [0043]     The vacuum source  102  is used to apply negative pressure through the vacuum cone  106  to stabilize the sheath  4  while delivering the elongated member  12  into, for example, a PFO tunnel. The vacuum applied to stabilize the sheath  4  may also have the advantage of collapsing the tunnel of the PFO. The lumen  128  of the vacuum cone  106  may be in communication with the lumen  10  of the sheath  4 .  
         [0044]     A cone, as used herein, means any tubular shape or any tubular shape with a flared end. In a preferred embodiment, the cone  106  includes a tube having a flared end, i.e., the diameter of the distal end  96  of the cone  106  is greater than the diameter of the proximal end  132  of the cone  106 . The flare may begin at the proximal end  132  of the cone  106  and extend gradually to the distal end of the cone  106  as illustrated in  FIG. 1B , or, alternatively, the flare may begin anywhere along the long axis of the cone  106  and extend to the distal end of the cone  106  (not shown). The distal end of the cone  106  may be circular, oval, U-shaped or any other shape suitable for interfacing with intracardiac tissue. According to the invention, the cone  106  and vacuum source  102  may or may not be present and the invention is not limited to an apparatus including a vacuum or other source of negative pressure. Furthermore, the cone  106  may be applied to the distal end of any sheath in the device and is not limited to the sheath illustrated.  
         [0045]     With continued reference to  FIG. 1B , in one embodiment, the cone  106  includes a single lumen  128  extending from the proximal end  132  of the cone  106  to the distal end of the cone  106 . The lumen  128  of the cone  106  houses the elongated member  12  and may be in communication with the lumen  10  of the sheath  4 . In one embodiment, the lumen  128  is in fluid communication with the lumen  10  of the sheath  4 . Alternatively, the cone  106  has a plurality of lumens  128  (not shown). One of the plurality of lumens  128  houses the elongated member  12 . At least one other of the plurality of lumens  128  is in fluid communication with the lumen  10  of the sheath  4 .  
         [0046]     Referring still to  FIG. 1B , in a preferred embodiment, a vacuum source  102  is operatively joined to the lumen  10  of the sheath  4  to the lumen  128  of the cone  106 .  
         [0047]     With further reference to  FIG. 1B , the elongated member  12  extends through the lumen  10  of sheath  4 . In one embodiment, the distal end  33  of the elongated member  12  transitions from a first position, where the distal end  33  of the elongated member  12  is housed within the lumen  10  to a second position, where the distal end  33  of the elongated member  12  is positioned beyond the distal end of the sheath  4  or the distal end of the cone  106  in embodiments including a cone  106 .  
         [0048]     According to one embodiment of the invention, the elongated member  12  includes a first material  14  and a second material  16 . In one embodiment, at least a portion of the second material  16  is interwoven with at least a portion of the first material  14 . In a particular embodiment, at least the second material  16  interwoven with first material  14  is an energy transferring material that can transfer energy from an energy source  34  to, for example, adjacent cardiac tissue. The second material  16  may be in the form of a thread, filament cord, rope, ribbon, plate or sheet, for example. In yet another embodiment, the elongated member  12  is transitioned from within the sheath  4  to extend beyond the distal end  6  of the sheath  4  to place the distal end of the elongated member  12  including the second material  16  in direct contact or, alternatively in indirect contact, for example, through water or saline, with cardiac tissue  18  in need of treatment.  
         [0049]     The elongated member  12  can be any shape depending on the intended use of the device  2  and/or the user&#39;s preference. In certain embodiments, the elongated member  12  comprises a straight wire or, alternatively, one or more bristles (not shown) at the distal end  33  of the elongated member  12 . In another embodiment, the elongated member  12  comprises a sleeve. In other embodiments, the elongated member  12  comprises a braid, coil, knot, spiral or zigzag shape. Alternatively, the elongated member  12  can be in the shape of a tube or a cone. In certain embodiments, the elongated member  12  includes a lumen. In other embodiments, the device of the invention comprises two or more elongated members  12 . Each elongated member  12  can be manipulated independently or in unison with the other(s) in the manner described below.  
         [0050]     In a particular embodiment, the second material  16  may be positioned on one or more bristles or braided, coiled, knotted, spiral or zig zag or bonded with the first material  14  on the elongated member  12 . For example, the first material  14  may be an insulator of the second material  16 . Uninsulated portions of the second material  16  are contacted with the tissue in need of treatment. Alternatively, the elongated member  12  may include only the second material  16 .  
         [0051]     With respect to the material of the elongated member  12 , by “interwoven” it is meant that at least a portion of the first material  14  and a portion of the second material  16  are connected closely by being in direct contact with each other, e.g., threaded, woven through or overlapping the other or indirect contact. By “direct contact” it is meant that at least a portion of the first material  14  and a portion of the second material  16  are physically touching each other. By “indirect contact” it is meant that at least a portion of the first material  14  and a portion of the second material  16  are in physical contact with a common object or common third material. By “threaded” it is meant that one material in the form of a thread or wire is physically passed into or through the other.  
         [0052]     In one embodiment according to the invention, the first material  14  and the second material  16  of the elongated member are different compositions. According to one embodiment, the first material  14  comprises, for example, a polymer, such as a plastic, for example, nylon or polyester. The second material  16  comprises any material capable of transferring energy, for example, electromagnetic energy, from an energy source to a target tissue, for example, cardiac tissue. In one embodiment, the second material is, for example, copper, gold, metal, platinum, silver, iron, lithium, cobalt, nickel, chromium, glass, ceramic or a combination thereof. The electromagnetic energy transferred may be, for example, one of microwave, infrared, visible light waves, ultraviolet light waves, x-ray, gamma ray, laser energy, or cosmic ray. In a particular embodiment, the electromagnetic energy is radio frequency energy.  
         [0053]     According to one embodiment of the invention, at least a portion of the second material  16  is interwoven with at least portion of the first material  14 . For example, the materials  14 ,  16  can cross each other one or more times, be braided together, threaded through one another, twisted together, coiled together, woven through each other, and/or knotted together. Alternatively, the materials  14 ,  16 , when placed adjacent to each other, can be collectively formed into the shape of a braid, coil, knot, spiral, zigzag, straight wire, or bristles. The material  14 ,  16  may be laminated or crimped together. The second material  16  extends from the energy source  34  to at least the distal end of the elongated member  12 .  
         [0054]     Referring now to  FIG. 1A , another embodiment of the invention features the sheath  4  operatively joined to an actuator  32 , positioned on, for example, a handle  30 , wherein movement of the actuator  32  causes axial movement of the sheath  4  relative to the stationary elongated member  12 . In another embodiment, the elongated member  12  is operatively joined to the actuator  32  wherein movement of the actuator causes axial movement of the elongated member  12  relative to the stationary sheath  4 . In one embodiment, the actuator is a knob or a button.  
         [0055]      FIG. 1C  is a schematic view of a cross section in  FIG. 1A  taken at  1 C- 1 C. As shown in  FIG. 1C , one embodiment of the invention features the elongated member  12  located within the lumen  10  of the sheath  4 .  
         [0056]      FIG. 2A  is a partial cross-sectional view of a distal end of a device  2  for treating cardiac tissue, the device  2  comprising an elongated member  12  retracted within a lumen  10  of the device  2  according to an illustrative embodiment of the invention. As shown in  FIG. 2A , one embodiment features an elongated member  12  comprising a distal end  33  and a proximal end  50 . According to the illustrative embodiment, the elongated member  12  is, for example, a single wire such as for example, a single braided wire comprising a hairpin turn  36  at the distal end  33  of the elongated member  12  to form an open loop configuration with the two free ends  52  of the wire located at the proximal end  50  of the elongated member  12 . In one embodiment, the elongated member  12  is in the form of a wire that forms a closed loop configuration at the distal end  33  of the elongated member  12 , with both of the ends  52  of the wire joined to each other or joined to a common object, for example, directly or indirectly to an actuator, at the proximal end  50  of the elongated member  12 .  
         [0057]     In one embodiment, the second material  16  follows the path of the first material  14  forming a bipolar device. Alternatively, the second material  16  partially follows the path of the first material  14 , forming a unipolar device.  
         [0058]     With continued reference to the embodiment shown in  FIG. 2A , at least one end  52  of the wire is operatively joined to an object, for example, a carrying cable  20 . According to one embodiment, the carrying cable  20  is connected to an actuator (not shown) such that actuation of the actuator effectuates movement of the cable  20  and the elongated member  12 . In a particular embodiment, movement of the actuator causes the elongated member  12  to move axially in relation to the sheath  4 , i.e., in a motion-parallel to the sheath  4  (as indicated by direction arrows  100  and  102 ). In another embodiment, movement of the actuator causes the elongated member  12  to move in a circumferential motion, i.e., rotational movement of the circumference of the loop in one or more directions as indicated by arrows  108  and  110 .  
         [0059]     In a further embodiment, the one end  52  of the wire that is not joined to the cable  20  is fixed within the device  2 . In another embodiment, as shown in  FIG. 2B , axial movement of the cable  20  in the distal direction allows the elongated member  12  to unfurl from the lumen  10  of the sheath  4 . By unfurl it is meant that the distal end portion  46  of the elongated member  12  moves in the distal direction to extend the length of the elongated member  12  from the proximal end  50  to the distal end  33  of the elongated member  12  while the end  52  remains stationary (similar to that of a bicycle chain, for example, with one end fixed) as indicated by direction arrows  104  and  106  in  FIG. 2A , relative to the sheath  4 . The distal end  33  of the unfurled elongated member  12  can be extended beyond the distal end  6  of the sheath  4 . Alternatively, axial movement of the cable  20  in the proximal direction can allow the distal end  33  of the elongated member  12  to move in the proximal direction and retract the distal end  33  of the elongated member further inside the lumen  10  of the sheath  4 .  
         [0060]      FIG. 2C  is a partial cross-sectional view of the distal end  6  of the device  2  for treating cardiac tissue  18  as illustrated in  FIG. 2A , with the elongated member  12  extended distally beyond the lumen  10  of the sheath  4  and in proximity to tissue in need of treatment according to an illustrative embodiment of the invention. As illustrated in  FIG. 2C , manipulation of the elongated member  12  according to each of the embodiments described above allows the portion  22  of the elongated member  12  comprising the first interwoven materials  14  and the second interwoven material  16  to be placed in a desired location within a patient&#39;s body. Energy is transferred from an energy source  34  to the second material  16  in contact with the target tissue  18  and from the second material  16  to the target tissue  18 .  
         [0061]     In a preferred embodiment, manipulation of the elongated member  12  carries the second material  16  into the PFO tunnel. Upon further manipulation of the elongated member  12 , the distal end of the elongated member retracts proximally, and leaves the PFO tunnel, and the second material transfer energy to the septum tissue along the track, and therefore causes the target tissue to fuse together.  
         [0062]      FIG. 2D  is a schematic view of a cross section in  FIG. 2C  taken at  2 D- 2 D. As shown in  FIG. 2D , according to the exemplary embodiment of  FIG. 2C , the elongated member  12 , for example, is a wire having a hairpin turn. One end of the wire is attached to the cable  20 . The elongated member  12  is axially positioned within the lumen  10  of the sheath  4 .  
         [0063]      FIG. 3A  is a partial cross-sectional view of a distal end portion  38  of a device  2  for treating cardiac tissue, the device  2  comprising an elongated member  12  in the form of a sleeve and a cable  20  for manipulating the elongated member  12  according to an illustrative embodiment of the invention. According to one embodiment, the sleeve  12  comprises an interior surface  42  and an exterior surface  44 . In the embodiment shown in  FIG. 3A , the portion of the elongated member  12  comprising the second material  16  interwoven with the first material  14  is located at least on the interior surface  42  of the sleeve  12 .  
         [0064]      FIG. 3B  is a schematic view of a cross section in  FIG. 3A  taken at  3 B- 3 B. In one embodiment, shown in  FIG. 3B , the sleeve  12 , located within the lumen  10  of the sheath  4 , comprises an interior surface  42  and an exterior surface  44 , wherein the portion of the sleeve  12  comprising the interwoven second material  16  is located on the interior surface  42  of the sleeve  12 .  
         [0065]     Referring now to the embodiment shown in  FIG. 3A , the portion of the elongated member  12  comprising the second material  16  interwoven with the first material  14  is initially located on the interior surface  42  of the sleeve  12 . According to one embodiment, the cable  20  is operatively joined to the exterior surface  44  of the sleeve  12 . Referring now to  FIG. 3C , axial movement of the cable  20  proximally in the direction indicated by direction arrow  112  lengthens the exterior surface  44  and shortens the interior surface  42  of the sleeve. At least a portion of the inner surface of the sleeve  12  becomes everted and at least a portion of the sleeve  12  comprising the interwoven second material  16  is relocated from the interior surface  42  to the exterior surface  44  of the sleeve  12 . In one embodiment for treating cardiac tissue, the portion of the everted sleeve  12  comprising the interwoven second material  16  contacts the tissue in need of treatment when the second material  16  on the distal end of the sleeve  12  is extended beyond the distal end of the sheath  4 , and electromagnetic energy from the energy source is transferred from the second material  16  to the tissue.  
         [0066]     Alternatively, in another embodiment (not shown), the cable  20  is operatively joined to the interior surface  42  of the sleeve  12 . Axial movement of the cable  20  in a distal direction lengthens the exterior surface  44  and shortens the interior surface  42  of the sleeve such that at least a portion of the interior surface  42  of the sleeve  12  becomes everted and at least a portion of the sleeve  12  comprising the interwoven second material  16  is relocated to the distal end of the sleeve  12  and the exterior surface  44  of the inverted sleeve  12 . In one embodiment for treating cardiac tissues, the portion of the everted sleeve  12  comprising the interwoven second material  16  contacts the tissue in need of treatment and electromagnetic energy from the energy source is transferred from the second material  16  to the tissue.  
         [0067]      FIG. 3D  is a schematic view of a cross section in  FIG. 3C  taken at  3 D- 3 D. In the exemplary embodiment, shown in  FIG. 3D , the sleeve  12  is located within the lumen  10  of the sheath  4  and the portion of the sleeve  12  comprising the interwoven second material  16  is located on both the interior surface  42  and the exterior surface  44  of the inverted sleeve  12 .  
         [0068]     Referring now to  FIGS. 3C and 3D , according to one embodiment of the invention, the sheath  4  of the device  2  moves relative to the sleeve  12  such that movement of the sheath  4  in the proximal direction exposes the sleeve  12  beyond the distal end of the sheath  4 . In another embodiment, the sleeve  12  moves relative to the sheath  4 , such that movement of the sleeve  12  in the distal direction exposes the sleeve  12  beyond the distal end of the sheath  4 .  
         [0069]     In further embodiments of the invention of the device  2 , the proximal end  8  of the sheath  4  is coupled to a vacuum source to allow functional communication with the lumen  10  of the sheath  4 . This configuration allows the user to apply negative pressure, i.e., suction, to the targeted cardiac tissue  18  as the distal end of the sheath  4  is applied to the tissue  18 . The negative pressure vacuum can be used to draw the cardiac tissue toward the second material  16 . With the tissue in contact with the second material  16 , energy transfers from the second material  16  directly to the tissue. In one embodiment, the negative pressure from the vacuum source is maintained while the energy is applied to the tissue.  
         [0070]      FIG. 4  is a schematic side view of a distal end  38  of a device  2  for treating cardiac tissue, the device  2  comprising a first sheath  4 , an elongated member  12  and a second sheath  24  surrounding the first sheath  4  according to an illustrative embodiment of the invention. The elongated member  12  may be any one of the elongated members illustrated in  FIGS. 1A-1C ,  2 A- 2 D, or  3 A- 3 D and described in the corresponding text. In one embodiment, as illustrated in  FIG. 4 , the lumen  26  of second sheath  24  surrounds the first sheath  4  and the first sheath  4  is located within the lumen  26  of the second sheath  24 . In another embodiment, the second sheath  24  is functionally joined to a vacuum source, for example, at the proximal end  28  of the second sheath  24 .  
         [0071]      FIG. 5  is a schematic side view of a distal end  38  of a device  2  for treating cardiac tissue, the device comprising a first sheath  4 , an elongated member  12  and a second sheath  24  within the lumen  10  of the first sheath  4 , according to an illustrative embodiment of the invention. In one embodiment, as shown in  FIG. 5 , the second sheath  24  is axially positioned within the lumen  10  of the first sheath  4  and surrounds the elongated member  12  such that the elongated member  12  is located within the lumen  26  of the second sheath  24 . In another embodiment (not shown), the second sheath  24  is within the lumen  10  of the first sheath  4  and adjacent to the elongated member  12 . In one embodiment, the second sheath  24  is functionally joined to a vacuum source, at, for example, a proximal end  28  of the second sheath  24 . In an even further embodiment (not shown), the elongated member  12  comprises a lumen, and the second sheath  24  functionally joined to the vacuum source is axially positioned within the lumen of the elongated member  12 . The elongated member  12  may be any one of the elongated members illustrated in  FIGS. 1A-1C ,  2 A- 2 D, or  3 A- 3 D and described in the corresponding text.  
         [0072]     The first sheath  4  and the second sheath  24  can be any shape suited to its function. For example, the sheath  4  or sheath  24  can be tubular or funnel shape. The sheath  4  or sheath  24  can have a lumen of uniform or variable diameter. For example, the sheath  4  or sheath  24  in a particular embodiment includes a flared distal end. In another embodiment, the sheath  4  or sheath  24  comprises an invertible sleeve.  
         [0073]      FIG. 6  is a schematic side view of a distal end  38  of a device  2  for treating cardiac tissue, the device  2  comprising an elongated member  12  having a first material  14  and a second material  16  interwoven with a portion of the first material  14 , according to an illustrative embodiment of the invention. In one embodiment, the second material  16  of the elongated member  12  is an energy transferring material. The elongated member  12  includes, for example, a flared distal end  30 . The portion of the elongated member  12  having at least a portion of the interwoven second material  16  is located on the flared distal end  30 . In a further embodiment, the elongated member  12  comprises a uniform fixed diameter. In other embodiments, the elongated member  12  comprises a lumen that is functionally joined to a vacuum source for the application of negative pressure to cardiac tissue.  
         [0074]     Another aspect of the invention features a method for treating cardiac tissue. The method comprises the steps of advancing a device  2  according to the invention to a position adjacent to cardiac tissue  18  in need of treatment, the device  2  includes a sheath  4  and at least one elongated member  12  slidably disposed with a lumen  10  of the sheath  4 . In one embodiment, the elongated member  12  includes a first material  14  and a second material  16 . At least a portion of the second material  16  is interwoven with a portion of the first material  14 . As described above with respect to other embodiments, the second material  16  is capable of transferring energy, for example, electromagnetic energy, from an energy source. According to this embodiment, the method comprises the step of advancing the elongated member  12  through the lumen  10  of the sheath. At least a portion of the second material  16  is placed into contact with cardiac tissue in need of treatment  18 . The method further includes the step of applying energy from the energy source to the second material  16  to transfer energy to the cardiac tissue  18  in need of treatment.  
         [0075]     In one embodiment according to this aspect of the invention, the energy applied to the cardiac tissue includes one of microwave, infrared, visible and ultraviolet light waves, x-ray, gamma ray, or cosmic ray. In another embodiment, the energy is radio frequency energy.  
         [0076]     According to a further embodiment of the method of the invention, an operator provides an elongated member  12  including a wire having a hairpin turn  36  at a distal end  33  of the elongated member  12  to form an open ended loop having two ends  52  of the wire at a proximal end of the elongated member  12 . At least one end  52  of the wire is operatively joined to an actuator  32 . Actuating the actuator  32  in the distal direction unfurls a portion of the elongated member  12  from the lumen  10  of the sheath  4  and moves the distal end  36  of the elongated member  12  in the distal direction. In an additional embodiment, the method further comprises the step of actuating the actuator  32  to move the elongated member  12  distally to place at least a portion of the second material  16  in contact with the cardiac tissue  18  in need of treatment. In a further embodiment, actuating the actuator  32  to move the elongated member  12  in the proximal direction retracts a portion of the elongated member  12  within the lumen  10  of the sheath  4  and moves the distal end  36  of the elongated member  12  in the proximal direction.  
         [0077]     A further embodiment of the invention includes an additional step of attaching a vacuum source to the lumen  10  of the sheath  4 . According to this embodiment, a vacuum or negative pressure, i.e., suction, is applied to the cardiac tissue  18  to draw the cardiac tissue  18  toward the device  2 . In another embodiment, the device  2  comprises a second sheath  24  having a lumen  26 , and the method comprises an additional step of attaching a vacuum source to the lumen  26  of the second sheath  24 . According to this embodiment, a vacuum can be applied to cardiac tissue to draw the tissue toward the device  2 . In both of these embodiments, the cardiac tissue drawn toward the device  2  is contacted with the second material  16  and energy is transferred from the second material  16  to the tissue  18 . The vacuum or negative pressure can also be maintained on the tissue while the energy is being applied to the tissue.  
         [0078]     A further aspect of the invention includes a method for treating cardiac tissue comprising the step of advancing a device  2  to a position adjacent to cardiac tissue in need of treatment, the device  2  having at least one elongated member  12  comprising a first material  14  and a second material  16 . At least a portion of the second material  16  is interwoven with at least a portion of the first material  14 . The second material  16  is capable of transferring energy from an energy source to a target tissue, for example, cardiac tissue. The method further comprises the steps of advancing the elongated member  12  through the body of a patient until at least a portion of the second material  16  comes into contact with the cardiac tissue in need of treatment, and applying the energy source to the second material  16  to transfer energy to the cardiac tissue in need of treatment.  
         [0079]     In yet another aspect, the invention provides methods for percutaneously closing a PFO using a device  2  such as the device according to the invention depicted in  FIGS. 1-6 . In one exemplary embodiment, an operator, e.g., a physician, advances the device  2  into the patient&#39;s heart with the elongated member  12  retracted within the lumen  10  of the sheath  4 . The operator then positions the distal end  6  of the sheath  4  in the right atrium proximate the PFO. With the device  2  positioned as such, the elongated member  12  is deployed into the tunnel of the PFO. As described above, the elongated member  12  is manipulated such that the portion of the elongated member comprising the interwoven second material  16  is exposed to the patient&#39;s tissue surface located within the tunnel of the PFO. The second material  16  is connected to an energy source, and energy is transferred from the second material  16  to the tissue surface to close the PFO. The physician then retracts the elongated member  12  from the PFO and removes the device  2  from within the patient.  
         [0080]     In a similar embodiment, the device  2  comprising the elongated member  12  is advanced within a patient as described above and is placed adjacent to the right atrial wall of the heart. The elongated member  12  comprises a vacuum which is placed in contact with the right atrial wall, and the portion of the elongated member  12  comprising the interwoven second material  16  is placed in contact with the tissue of the right atrial wall. The vacuum is then activated, attaching the elongated member  12  to the right side of the fossa ovalis. Energy is then delivered to the second material  16  from an energy source, and the energy is transferred from the second material  16  to the fossa ovalis. The energy is absorbed by the surrounding cardiac tissue to close the PFO.  
         [0081]     In yet another embodiment of the method according to the invention, the elongated member of the device described herein may be used to delivery energy to the tissues within the tunnel of a PFO as described in co-owned application titled, “In tunnel electrode for sealing intra-cardiac defects”, co-filed on the same date as the instant application and incorporated by reference in its entirety herein.  
         [0082]     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. The invention is not to be defined only by the preceding illustrative description.