Abstract:
Device, system and method for drawing together patient tissue. A central hub has an axis. Several tines are coupled to the central hub. Each of the tines has a tip and is resiliently biased to form a coil. Each tip points radially outward from the axis, with an approximately common angle between adjacent ones of the tines.

Description:
FIELD 
     The present invention relates generally to devices, systems and methods of drawing patient tissue together, and in particular such devices, systems and methods of drawing patient tissue together using a medical clip. 
     BACKGROUND 
     In many circumstances and for many reasons, it is often beneficial to capture and draw together two or more pieces of tissue of a patient. The location of the tissue and the circumstances of the need to draw the pieces of tissue together have long resulted in a variety of different devices and methods for drawing the tissue together. Devices such as bandages, both self-adhesive and otherwise, clamps and stitches have been used to capture pieces of tissue and draw them together. Once tissue is drawn together, the natural healing abilities of the body may then allow the pieces of tissue to grow together, over time sealing a gap between the pieces of tissue such that the device is no longer needed. Alternatively, the pieces of tissue may be held together by the device indefinitely, or for a particular period of time. 
     But, dependent on the location of the tissue, certain devices and methods may be impractical to utilize. For instance, while stitches may lend themselves well to readily accessible patient tissue, such as skin and muscle tissue, relatively inaccessible tissue, such as that found in the organs of the patient, may be impractical to capture and draw together using stitches. As such, the use of stitches to treat a defect in a patient&#39;s heart may tend require a traumatic open heart procedure, and even then, because the interior of the heart still may not be readily accessible, the treatment of a defect inside the heart may still not be attainable with stitches. Thus, a common device and method for drawing together patient tissue may not be applicable for all situations, particularly those involving a defect in organs of the patient such as the heart. 
     One relatively common defect in the heart of newborn children, which may also be present in older children and in adults, is a patent foramen ovale (“PFO”). During the gestation of a fetus in the womb, blood is oxygenated not by the undeveloped lungs of the fetus, but rather by the placenta of the mother. However, the heart of the fetus nevertheless pumps the blood through the cardiovascular system and receives the blood from the cardiovascular system. As such, in order to avoid the undeveloped lungs of the fetus, various vessels and bypasses exist that operate only during gestation that divert the blood from the lungs. At birth these bypasses typically close and circulation occurs by way of the lungs as with a normally developed adult. 
     An opening between the right atrium and the left atrium called the foramen ovale is open during gestation to prevent transfer of blood from the right ventricle of the heart to the lungs during gestation. Upon birth, the child&#39;s inherent circulation creates pressure within the atrium which causes a flap of tissue to close over the foramen ovale. As the child matures, the flap of tissue develops into a permanent closure. However, in some children the flap of tissue does not close, either in whole or in part, over the entire foramen ovale, creating a patent foramen ovale. The continued existence of the foramen ovale results in continued diversion from the lungs of at least some of the child&#39;s blood, reducing the flow of oxygenated blood through the child&#39;s system, and potentially leading to serious complications to the health of the child. 
     It is recognized that although PFO may occur most prominently in children and, in particular, relatively newborn children, that the PFO may also occur or be present in older children and in adults. 
     Other cardiac defects are known to exist beyond patent foramen ovales. For instance, atrial-septal defects (“ASD”) and ventricular-septal defects (“VSD”) likewise sometimes occur and may be detrimental to the health of the person, e.g., a child. Historically, open heart surgery had been required to fix such defects. But open heart surgery carries with it serious and well-known and recognized risks to the well-being of the person, in addition to being expensive and a considerable burden on hospital resources. 
     Closure devices for treating heart defects, such as patent foramen ovales, have been developed. 
     U.S. Pat. No. 6,776,784, Ginn, Clip Apparatus For Closing Septal Defects and Methods of Use, (Core Medical, Inc.) discloses a device for closing a septal defect, such as a patent foramen ovale, includes a clip formed from a superelastic material that is inserted into a septum wall of a heart. The clip is advanced through a patient&#39;s vasculature, e.g., within a delivery apparatus, until the clip is disposed within a first chamber adjacent the septal defect. Tines of the clip are directed through a flap of tissue of the septal defect until the tines of the clip are disposed within a second opposing chamber. The clip then transforms into its relaxed state, wherein the tines of the clip engage with a surface of the second chamber, thereby substantially closing the septal opening. 
     U.S. Patent Application Publication No. US2007/0060858, Sogard et al, Defect Occlusion Apparatus, System and Method, discloses occluding a multiplicity of parallel membranes, such as found in a patent foramen ovale. The methods, apparatus, and systems include the use of a positioning device that can be seated on the limbus of the septum secundum. The positioning device includes a piercing member that can pierce the septum secundum and septum primum. The positioning device also includes a fastening member that can engage the septum secundum and septum primum to fasten the tissues and thereby occlude a patent foramen ovale. 
     U.S. Pat. No. 7,220,265, Chanduszko et al, Patent Foramen Ovale (PFO) Closure Method and Device, (NMT Medical, Inc.) discloses methods and devices for closing two overlapping layers of tissue in a mammalian heart, such as a patent foramen ovale. The closure devices may take a number of different forms and may be retrievable. In some embodiments, the closure devices may be delivered with a catheter capable of puncturing mammalian tissue. In some embodiments, a spring-like bioabsorbable polymer material are used, in one such embodiment as a “grappling hook”, to embed in and draw together the pieces of tissue. In another embodiment, a suture is delivered, and an anchor forms a pre-determined shape and engages the septum secundum, closing the patent foramen ovale. 
     SUMMARY 
     Closure devices for treating patent foramen ovales have been developed that allow for the treatment of patent foramen ovales and other cardiac defects without conducting open heart surgery. Instead, the closure devices may be utilized to cure or treat cardiac defects by way of transveneous implantation. With the device placed in a sheath attached to a catheter small enough to pass through the blood vessels of the child and into the heart, the device may be deployed in the heart to treat the cardiac defect. 
     The device itself may be made of a number of joined tines, each of which form a loop, perhaps sharpened at the end to allow for puncturing the cardiac tissue of the patient. Outside of the implantation sheath each tine may be biased so that each tine forms a loop or coil in a relaxed state. Inside of the sheath the tines are uncoiled to be relative linear, possibly giving the device an adequately small profile to allow passage of the device through a vein or other vascular component of the patient. When the device is deployed from the sheath the tines may curl into a biased (relaxed) coiled form. During a transition from a relatively linear configuration to a coiled configuration, as the device is deployed from the sheath, within the heart the sharpened end of the tines may pass through cardiac tissue. In the case of the treatment of a patent foramen ovale, if the device is positioned adjoining the two flaps of tissue which did not automatically close together, at least one approximately linear tine may pass through each flap of tissue as coils are formed. As the tines complete forming a coil, the two flaps of tissue may be drawn together, either closing the foramen ovale altogether, or bringing the flaps of tissue in closer proximity of each other such that vascular pressure may ultimately bring the flaps of tissue together. As the patient matures flaps of tissue may grow together and the foramen ovale close permanently. 
     In an embodiment, a medical clip is disclosed for drawing together patient tissue. The medical clip comprises a central hub having an axis and a plurality of tines coupled to the central hub. Each individual one of the plurality of tines has a tip and is resiliently biased to form a coil with the tip pointing radially outward from the axis with an approximately common angle between adjacent ones of the plurality of tines. 
     In an embodiment, each of the plurality of tines may be flexed to be approximately linear. 
     In an embodiment, each coil of each individual one of the plurality of tines comprises at least one full revolution. 
     In an embodiment, each coil of each individual one of the plurality of tines comprises at least one-and-a-quarter revolutions. 
     In an embodiment, the plurality of tines are configured to pass through the patient tissue. 
     In an embodiment, the plurality of tines are configured to draw a first piece of the patient tissue together with a second piece of the patient tissue. 
     In an embodiment, at least one of the plurality of tines passes through the first piece of the patient tissue and at least one other one of the plurality of tines passes through the second piece of the patient tissue during a transition from being approximately linear to being coiled. 
     In an embodiment, the first piece of the patient tissue is drawn together with the second piece of the patient tissue when the plurality of tines are coiled. 
     In an embodiment, the tips point approximately orthogonal to the axis. 
     In an embodiment, the plurality of tines are comprised of nitinol. 
     In an embodiment, a system for drawing together patient tissue is disclosed. The system comprises a medical clip, comprising a central hub having an axis and a plurality of tines coupled to the central hub. Each individual one of the plurality of tines has a tip and is resiliently biased to form a coil with the tip pointing radially outward from the axis with an approximately common angle between adjacent ones of the plurality of tines. The system further comprises a delivery catheter. The delivery catheter comprises a lumen containing the medical clip with each of the plurality of tines being flexed to be approximately linear by the delivery catheter and a deployment mechanism positioned within the lumen adapted to deploy the medical clip by pushing the medical clip out of an opening in the delivery catheter. Each of the plurality of tines form into the coil when the medical clip is deployed from the delivery catheter. 
     In an embodiment, a medical clip is disclosed for drawing together patient tissue. The medical clip comprises a central hub having an axis and four tines coupled to the central hub. Each individual one of the four tines has a tip and is resiliently biased to form a coil with the tip pointing radially outward from the axis with an approximately common angle between adjacent ones of the four tines. 
     In an embodiment, each of the four tines may be flexed to be approximately linear. 
     In an embodiment, each coil of each individual one of the four tines comprises at least one full revolution. 
     In an embodiment, each coil of each individual one of the four tines comprises at least one-and-a-quarter revolutions. 
     In an embodiment, the four tines are configured to pass through the patient tissue. 
     In an embodiment, the four tines are configured to draw a first piece of the patient tissue together with a second piece of the patient tissue. 
     In an embodiment, at least one of the four tines passes through the first piece of the patient tissue and at least one other one of the four tines passes through the second piece of the patient tissue during a transition from being approximately linear to being coiled. 
     In an embodiment, the first piece of the patient tissue is drawn together with the second piece of the patient tissue when the four tines are coiled. 
     In an embodiment, the tips point approximately orthogonal to the axis. 
     In an embodiment, the four tines are comprised of nitinol. 
     In an embodiment, a method is disclosed for drawing together tissue of a patient using a medical clip having a central hub coupled to a plurality of tines each resiliently biased to form a coil with a tip pointing radially outward from an axis of the central hub with an approximately common angle between adjacent ones of the plurality of tines. The method comprises the steps of placing a delivery catheter having a lumen containing the medical clip between a first piece of the tissue and a second piece of the tissue, wherein the plurality of tines are straightened while in the delivery catheter and deploying the medical clip from the delivery catheter. At least one of the plurality of tines passes through the first piece of tissue and at least one other of the plurality of tines passes through the second piece of tissue. The first piece of tissue and the second piece of tissue are drawn together when the plurality of tines coil. 
     In an embodiment, a method is disclosed for treating a patent foramen ovale using a medical clip having a central hub coupled to a plurality of tines each resiliently biased to form a coil with a tip pointing radially outward from an axis of the central hub with an approximately common angle between adjacent ones of the plurality of tines. The method comprises the steps of placing a delivery catheter having a lumen containing the medical clip between a first piece of tissue of the patent foramen ovale and a second piece of tissue of the patent foramen ovale, wherein the plurality of tines are straightened while in the delivery catheter and deploying the medical clip from the delivery catheter. At least one of the plurality of tines passes through the first piece of tissue of the patent foramen ovale and at least one other of the plurality of tines passes through the second piece of tissue of the patent foramen ovale. The patent foramen ovale is reduced in size when the first piece of tissue of the patent foramen ovale and the second piece of tissue of the patent foramen ovale are drawn together when each of the plurality of tines form the coil. 
     In an embodiment, the patent foramen ovale is substantially closed when each of the plurality of tines form the coil. 
    
    
     
       DRAWINGS 
         FIG. 1  shows a medical clip for drawing together patient tissue; 
         FIG. 2  shows the medical clip of  FIG. 1  positioned in a deployment catheter; 
         FIG. 3  shows the medical clip of  FIG. 1  deployed from, but still coupled to the deployment catheter; 
         FIGS. 4   a - 4   c  illustrate the positioning and deployment of the medical clip of  FIG. 1  for the treatment of a patent foramen ovale; 
         FIG. 5  is a flowchart for implanting a medical clip; and 
         FIG. 6  is a flowchart for making a system including a medical clip positioned in a deployment catheter. 
     
    
    
     DESCRIPTION 
     It is often advantageous to capture and draw together pieces of tissue of a patient. Doing so may close and help wounds heal, or close defects in patient organs. Various capture and closure devices exist, but while such devices may be effective in certain situations and under certain conditions, they may be ineffective or disadvantageous in other conditions. Particularly in situations where the tissue to be drawn together is not readily accessible to personal manipulation, commonly known devices are often of limited use. The treatment of cardiac defects may be one such relatively common situation. 
     In order to treat cardiac defects such as a patent foramen ovale, it is desirable close the gap between flaps of cardiac tissue without having to experience the trauma and expense of open heart surgery. Accordingly, a medical clip and delivery system has been developed that may be inserted into the heart intravenously. Upon positioning the delivery system within the gap of the patent foramen ovale, a deployment system deploys the medical clip. The physical nature of the medical clip captures and draws together the flaps of tissue of the patent foramen ovale, thereby reducing or closing the gap altogether. 
     An embodiment of a medical clip for treating cardiac defects is illustrated in  FIG. 1 . Clip  10  has central hub  12 . Four tines  14 ,  16 ,  18 ,  20  project from central hub  12 . In alternative embodiments more or fewer tines  14 ,  16 ,  18 ,  20  than four are utilized. Each tine  14 ,  16 ,  18 ,  20  is comprised of coil  22  and end  24 . In an embodiment, end  24  forms a sharpened tip. In the illustrated embodiment, tines  14 ,  16 ,  18 ,  20  are coupled to central hub  18 , with end  24  of each tine  14 ,  16 ,  18 ,  20  pointing radially outward from central hub  12 . 
     Tines  14 ,  16 ,  18 ,  20  may be made from a variety of different materials. Any material may be used such that tines  14 ,  16 ,  18 ,  20  may be resiliently biased to form coil  22  when clip  10  has been deployed, provided the material is biocompatible or may be treated to make it biocompatible. In an embodiment, tines  14 ,  16 ,  18 ,  20  are made from the shaped memory alloy Nitinol. In alternative embodiments, biocompatible elastic material such as stainless steel may be utilized. Biocompatible super-elastic materials may also be utilized. Super-elastic materials could encompass super-elastic plastics and super-elastic metals. A super-elastic plastic generally is any material that has shape memory ability after shaped setting, e.g., materials described in the Massachusetts Institute of Technology, News Office article entitled “Intelligent Plastics Change Shape With Light, dated Apr. 13, 2005, authored by Elizabeth A. Thomson, which is hereby incorporated by references in its entirety. Super-elastic metals are sometimes known as a shape memory alloy (also, smart metal, memory alloy or muscle wire) that remembers its shape and can be returned to that shape after being deformed, by applying heat to the alloy. When the shape memory effect is correctly harnessed, super-elastic metals becomes a lightweight, solid-state alternative to conventional actuators such as hydraulic, pneumatic and motor-based systems. In an embodiment, drawn filled tubes filled with a super-elastic material or materials. 
     In a further alternative embodiment, spring-like bioabsorbable material may be utilized, which may result in clip  10  ultimately dissolving. Alternatively, a non-bioabsorbable material may be utilized to form clip  10 , but the material may be coated with biological tissue, bioabsorbable polymer, a therapeutic substance or other substance which may be advantageously delivered to the treatment site concurrent with clip  10 . 
     In the illustrated embodiment of  FIG. 1 , coils  22  create a full circular loop, whereby a completed circle is formed because individual tines  14 ,  16 ,  18 ,  20  complete an approximately circular circuit. As illustrated, tines  14 ,  16 ,  18 ,  20  complete one-and-a-quarter revolutions, with the overlap providing potentially enhanced ability to hold tissue over a coil which completes only one full revolution. Alternatively, coils  22  may form only a partial circular loop. In an embodiment, coil  22  may be only three-quarters of a completed circle. In such an embodiment, the tissue captured in coil  22  may be sufficiently secured that the flaps of tissue may be drawn together even without coil  22  forming a completed circle. Alternative partial loops may also be utilized such that the tissue may still be captured and retained by coil  22 . In further alternative embodiments, non-circular loops may also be utilized. Oval or ellipsoid shapes may be utilized advantageously in certain circumstances. Alternatively, shapes with angles such as triangles or rectangles may be utilized. Further, irregular shapes may be utilized. 
       FIG. 2  illustrates an embodiment of clip  10  in an embodiment of a deployment catheter  48  having sheath  50 . To place clip  10  in sheath  50 , central hub  12  may be drawn into lumen  52  of sheath  50 . As central hub  12  is drawn in to sheath  50 , coil  22  of each tine  14 ,  16 ,  18 ,  20  is stressed by sheath  50 , causing coil  22  to unwind and each tine  14 ,  16 ,  18 , to become approximately straight when positioned in sheath  50 . End  24  of each tine  14 ,  16 ,  18 ,  20  remains in proximity of the distal end of sheath  50 . 
     Sheath  50  may be coupled to catheter  54  to form deployment catheter  48 . Catheter  54  may be utilized to guide sheath  50  into position to deploy clip  10 . Catheter  54  may also be utilized to deploy clip  10 . In an embodiment, catheter  54  has a deployment mechanism  56  in contact with central hub  12 . When deployment mechanism  56  pushes central hub  12 , clip  10  slides along sheath  50  until clip  10  has fully emerged from sheath  50 . 
       FIG. 3  illustrates an embodiment of clip  10  fully emerged from sheath  50  but still attached to deployment mechanism  56 . In the illustrated embodiment, tines  14 ,  16 ,  18 ,  20  have returned to their resiliently biased coiled state. In various embodiments of clip  10 , dependent on the material from which tines  14 ,  16 ,  18 ,  20  were made, tines  14 ,  16 ,  18 ,  20  may coil within moments of emerging from sheath  50 , or may require a lengthier amount of time to coil. In certain embodiments, tines  14 ,  16 ,  18 ,  20  may, for a time, remain essentially straight even after central hub  12  has emerged from sheath  50  due to the length of time required to coil. However, in such an embodiment, tines  14 ,  16 ,  18 ,  20  will eventually coil after clip  10  has deployed from sheath  50 . 
       FIGS. 4   a - 4   c  and the flowchart of  FIG. 5  illustrate a use of clip  10  and sheath  50  in the treatment of a patent foramen ovale. Sheath  50  is positioned ( FIG. 5 ,  200 ) in a gap  106  between a first flap of tissue  100  and a second flap of tissue  102  within heart  104  while clip  10  remains in sheath  50  with tines  14 ,  16 ,  18 ,  20  uncoiled ( FIG. 4   a ). As clip  10  is deployed ( FIG. 5 ,  202 ) from sheath  50 , tines  14 ,  16 ,  18 ,  20  begin to coil, with the coiling motion causing ( FIG. 5 ,  204 ) end  24  of at least one tine  14 ,  16 ,  18 ,  20  passing through tissue  100  and end  24  of at least one other tine  14 ,  16 ,  18 ,  20  passing through tissue  102  ( FIG. 4   b ). As tines  14 ,  16 ,  18 ,  20  complete coiling, tissue  100  and tissue  102  are drawn ( FIG. 5 ,  206 ) together by the decrease in the radius of coil  22  as each tine  14 ,  16 ,  18 ,  20  coils. The completion of coiling may draw tissue  100  and tissue  102  completely together and close gap  106  ( FIG. 4   c ). Alternatively, the completion of coiling may draw tissue  100  and tissue  102  nearly together though still leaving a reduced gap  106 . 
     The treatment of other cardiac defects, such as atrial-septal defects (“ASD”) and ventricular-septal defects (“VSD”), by the same steps illustrated above is also contemplated. In fact, any patient condition in which it is desirable to join or draw together two flaps of tissue may be effectively treated utilizing the steps illustrated in  FIGS. 4   a - 4   c . While the physical dimensions of clip  10  and delivery catheter  54  may need to change to reflect the different conditions, such as a wider gap  106  or tougher or thicker tissue  100 ,  102 , the method of using clip  10  may remain unchanged. 
     In various implementations of the deployment of clip  10 , tissue  100  and tissue  102  may be drawn together even if one or two of tines  14 ,  16 ,  18 ,  20  do not pass through tissue as intended. So long as at least one tine  14 ,  16 ,  18 ,  20  passes through each flap of tissue  100 ,  102 , tissue  100  may be drawn together with tissue  102 . Instances in which all four tines  14 ,  16 ,  18 ,  20  pass through tissue  100 ,  102  may, however, create the highest likelihood of maximizing the amount of tissue  100 ,  102  brought together. 
     The geometry of the components of clip  10  influence performance of clip  10 . Relatively longer tines  14 ,  16 ,  18 ,  20  and relatively greater diameter of coil  22  may allow for the treatment of a relatively larger gap  106 , or result in greater depth of penetration of tissue  100 ,  102 , perhaps increasing the likelihood of closing gap  106  altogether. And a relatively greater diameter of the material comprising tines  14 ,  16 ,  18 ,  20  may increase the ability of tines  14 ,  16 ,  18 ,  20  to hold tissue  100 ,  102  and decrease the likelihood of tissue  100 ,  102  slipping out of tines  14 ,  16 ,  18 ,  20  during or after coiling. In an embodiment, the dimensions of coil  22  is approximately 0.090 inches, and the diameter of tines  14 ,  16 ,  18 ,  20  is 0.014 inches. 
       FIG. 6  is a flowchart of a method for making an system in which an embodiment of medical clip  10  is positioned in deployment catheter  48 . Medical clip  10  is formed ( 300 ) by coupling tines  14 ,  16 ,  18 ,  20  to central hub  12 . Medical clip  10  is inserted ( 302 ) into lumen  52  of delivery catheter  48 . In an embodiment, central hub  12  is inserted into lumen  52  first, followed by tines  14 ,  16 ,  18 ,  20 . As the insertion occurs, tines  14 ,  16 ,  18 , uncoil until they are approximately linear within lumen  52 . Deployment mechanism  56  is inserted ( 304 ) into lumen  52 , such that when the deployment mechanism is used, medical clip  10  deploys out of lumen  52  and tines  14 ,  16 ,  18 ,  20  coil. In embodiments where deployment mechanism  56  is coupled to medical clip  10 , coupling deployment mechanism  56  to medical clip  10  may occur either before or after insertion of medical clip into delivery catheter  48 . When coupling occurs before insertion of medical clip  10 , deployment mechanism  56  may be utilized to insert medical clip  10  into deployment catheter  48  by pulling medical clip into lumen  52 . 
     Thus, embodiments of the devices, system and methods of drawing patient tissue together are disclosed. One skilled in the art will appreciate that the present invention can be practiced with embodiments other than those disclosed. The disclosed embodiments are presented for purposes of illustration and not limitation, and the present invention is limited only by the claims that follow.