Abstract:
Apparatus is provided that can be delivered through a catheter to a remote location in a patient&#39;s body. The apparatus may include a first structure that can be positioned in all dimensions in a controlled manner and stabilized in that desired position, a second structure that can then position a lumen axis at a desired angle relative to the first structure, and a third member that can pass through the lumen and approach and engage with force (e.g., penetrate) a desired location on the anatomy without compromising maintaining the desired position. The apparatus effectively separates the forces needed for positioning and the forces needed for tissue engagement (e.g., penetration).

Description:
This invention claims the benefit of U.S. provisional patent application No. 60/658,291, filed Mar. 2, 2005, which is hereby incorporated by reference herein in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to medical procedures and apparatus, and more particularly to medical procedures and apparatus that employ catheters to reach remote locations in a patient&#39;s body. 
     Certain catheter-based medical procedures may benefit from first establishing reference point apparatus at a remote location in the patient&#39;s body. Then an actual procedure can be performed in relation to the reference point apparatus. Examples of what is being referred to are procedures that involve crossing the atrial septum by piercing the septum from the right atrium to the left atrium such as in an ablation procedure, closing a patent foramen ovale (“PFO”), and any other left atrial procedure. If this could be done starting from stable and secure reference apparatus already in place at a desired location in the right atrium, the penetration of the septum could be made more precise, safer, and easier. It is therefore an object of this invention to provide such reference apparatus that can be delivered and deployed via a catheter, and which then provides a stable and secure “platform” from which one or more further procedures can be carried out. 
     SUMMARY OF THE INVENTION 
     Catheter delivered apparatus in accordance with the invention includes a first structure that can be positioned in all three dimensions in a controlled manner at a remote location inside a patient&#39;s body and stabilized in that desired position. The apparatus may further include a second structure that can then position a lumen axis at a desired angle relative to the first structure. A third structure may then pass through the second structure and approach and engage with force the desired location without compromising maintaining that location. The apparatus may thus effectively separate the forces needed for positioning from the forces needed for tissue engagement (e.g., penetration), thereby providing a safer and more controlled engagement (e.g., penetration) of the tissue. 
     In another aspect of the invention, catheter delivered apparatus in accordance with the invention includes a first expandable structure that can be positioned on one side of a tissue structure edge and a second expandable structure that can be positioned on the other side of the tissue structure edge, the first and second expandable structures being resiliently biased to diverge from one another so as to receive and engage the tissue structure edge between the first and second structures. At least the first structure includes at least two dimensions when expanded. The divergence of the second structure from the first structure involves use of a third dimension relative to the two previously mentioned dimensions. The first and second structures are preferably resiliently biased to expand, and are resiliently collapsible to approximately one dimension for delivery and removal via a catheter. 
     An illustrative use of the apparatus is in relation to a patient&#39;s PFO. One of the first and second structures can be deployed on one side of the limbus of the septum secundum (the upper portion of the septum between the left atrium and the right atrium of the heart). The other of the first and second structures can be deployed on the other side of the limbus. The structure on the PFO tunnel side of the limbus may enter and be self-centering in that tunnel. By engaging the limbus in this way, the engaging apparatus is prevented from being pushed farther into the heart. It is also located at a particular site in the heart and it is very stable at that location. For example, by straddling the limbus, by entering the PFO tunnel, and by including at least one structure that includes two dimensions substantially parallel to an adjacent tissue surface, the distal end of the apparatus is substantially prevented from rotating. This stable apparatus can be used as a “platform” for guiding other apparatus to a particular location and along a particular axis in the heart. 
     Further features of the invention, its nature and various advantages, will be more apparent from the accompanying drawings and the following detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a simplified sectional view of a portion of a patient&#39;s anatomy. 
         FIG. 2  is a view taken along the line  2 - 2  in  FIG. 1 . 
         FIG. 3  is a view similar to  FIG. 1  showing a portion of an illustrative embodiment of apparatus in accordance with the invention. 
         FIG. 4  is a view taken along the line  4 - 4  in  FIG. 3 . 
         FIG. 5  is another view similar to  FIG. 1  showing a portion of an illustrative embodiment of other apparatus in accordance with the invention. 
         FIG. 6  is a view taken along the line  6 - 6  in  FIG. 5 . 
         FIG. 7  is a simplified elevational view of an illustrative embodiment of a portion of illustrative apparatus in accordance with the invention. 
         FIG. 8  is a simplified sectional view taken along the line  8 - 8  in  FIG. 7 . 
         FIG. 9  is similar to  FIG. 7  showing the apparatus in another operating conduction. 
         FIG. 10  is a simplified isometric view of another illustrative embodiment of apparatus in accordance with the invention. 
     
    
    
     DETAILED DESCRIPTION 
     Although the invention has other uses and can be modified in various respects for at least some of those other uses, the invention will first be described in the context of its application to transeptal punctures in patients with and without a patent foramen ovale (“PFO”). Later in this specification examples of other uses and possible modifications will be discussed. 
     The structure (anatomy) of a typical PFO is shown in  FIGS. 1 and 2 . The features shown in these FIGS. are as follows: right atrium  10 , left atrium  20 , septum secundum  30 , septum primum  40 , PFO  50  (a passageway through the septum between the left and right atria that is somewhat like a pocket with no bottom), limbus  60  of the septum secundum, wall  70  of the inferior vena cava, and edges  90  of the PFO tunnel where the primum and secumdum join (although in a PFO the primum and secundum do not join at the upper end of that tunnel). Also shown in  FIGS. 1 and 2  is an axis and location  80  that are often regarded as particularly desirable for a transeptal puncture. The present invention provides instrumentation for facilitating such a transeptal puncture (although it will also be explained how the invention can alternatively facilitate puncture elsewhere). 
       FIGS. 3 and 4  show an illustrative embodiment of a portion of apparatus in accordance with the invention, which apparatus has been positioned in relation to the PFO also in accordance with the invention. It is emphasized that  FIGS. 3 and 4  show only a portion of the apparatus. In actual practice the components shown in  FIGS. 3 and 4  would not be separated from other components and would not be in the patient unconnected to other components. But for clarity of initial depiction and explanation, it is helpful to first show these apparatus components in isolation. 
     The apparatus components shown in  FIGS. 3 and 4  can be metal, wire-like components (e.g., of a highly elastic material such as nitinol). These apparatus components may be described as including three V-shaped parts  110 ,  120 , and  130 . V-shaped part  110  is partly positioned in the PFO tunnel  50 . The apex of V  110  extends the greatest distance into the PFO tunnel. The spaced ends of V  110  may be just outside the PFO tunnel (i.e., still in right atrium  10 ). 
     Both of Vs  120  and  130  are in the right atrium. The spaced ends of V  120  are connected to or near the spaced ends of V  110 . V  120  is resiliently biased to have the plane in which it lies diverge from the plane in which V  110  lies. This divergence causes V  120  to lie on the opposite side of septum secundum  30  from the side of that tissue structure on which V  110  lies. In other words, whereas V  110  is mostly in PFO tunnel  50  on one side of secundum  30 , V  120  is in right atrium  10  on the other side of secundum. The planes in which Vs  110  and  120  lie form a V-shaped trough ( FIG. 3 ) in which the limbus  60  of septum secumdum  30  lies. 
     The spaced ends of V  130  are connected to or near the spaced ends of Vs  110  and  120 . Whereas the apexes of Vs  110  and  120  point generally upward in the heart, the apex of V  130  points generally down (toward the inferior vena cava, represented in part by wall  70 ). 
     Vs  110 ,  120 , and  130  may be referred to collectively as structure  100 . 
     Note that V  110  generally centers structure  100  in PFO tunnel  50  (i.e., between the edges  90  of the PFO tunnel). Vs  110  and  120  cooperate to stop upward movement of structure  100  when the trough between the planes of those two Vs reaches limbus  60 . The relatively wide spacing between the free ends of all of Vs  110 ,  120 , and  130 , and the engagement of various portions of the Vs with adjacent tissue surfaces, tends to prevent structure  100  from rotating about an axis such as one that passes through the apexes of Vs  110  and  130 . In other words, V  110  (for example) tends to remain relatively flat against the surface of septum primum  40 . 
     Structure  100  is resiliently laterally collapsible. By this it is meant that the spaced apart ends of each of Vs  110 ,  120 , and  130  can be collapsed together (thereby substantially closing each of the Vs from two dimensions to one dimension). In addition, Vs  110  and  120  are resiliently collapsible toward one another (i.e., so that they are nearly in the same plane or, if Vs  110  and  120  are each also collapsed, then they are both nearly on the same line). V  130  is also resiliently deflectable into alignment with the other fully collapsed and aligned Vs, although the components of V  130  continue to extend away from the components of the other Vs. 
     In the collapsed and aligned condition described in the preceding paragraph, structure  100  can be delivered percutaneously into the patient&#39;s heart via a catheter. For example,  FIGS. 5 and 6  show catheter apparatus  300  that may be used to deliver structure  100  (and related components) to the site shown in  FIGS. 3 and 4 . Catheter  300  reaches the patient&#39;s heart via the patient&#39;s circulatory system, leading ultimately to the inferior vena cava. The distal portion of catheter  300  is resiliently shaped (as generally shown in  FIGS. 5 and 6 ) to contact vena cava wall  70  and from that point to aim toward PFO  50 . If desired, a guidewire  200  may be extended from the distal end of catheter  300  into and through PFO  50 . Guidewire  200  can help to make sure that the distal end of catheter  300  remains properly positioned relative to the entrance to the PFO, and it can also serve as a rail alone which additional components can be pushed from the end of catheter  300  into the PFO. Although this is something of a simplification (to be more fully explained below), structure  100  can be pushed from the distal end of catheter  300 , and when thus freed from constraint by the catheter, structure  100  resiliently expands to the condition shown in  FIGS. 3 and 4 . When structure  100  is no longer needed in the patient, it can be collapsed back into the catheter and withdrawn from the patient with or via the catheter. 
       FIG. 7  shows the components on which structure  100  is mounted in catheter  300  (although  FIG. 7  shows the condition of the apparatus after these components and structure  100  have been pushed out of the distal end of the catheter). The components shown in  FIG. 7  include distal tubular member  410 , tubular member  420 , linking member  430 , guide structure  440 , and proximal link member  450 . These elements are all rigidly secured to one another, and they may sometimes be referred to collectively as assembly  400 . Associated with these elements (but movable relative to them) is delivery tube  500 . 
     Tube  410  may be made of a relatively soft and flexible plastic material in order to make the distal end of assembly relatively atraumatic. Guide wire  200  ( FIGS. 5 and 6 ) may pass through tube  410  (or tube  410  may itself perform a function like a guide wire by being an early entrant into PFO tunnel  50  in the manner shown for guide wire  200  in  FIGS. 5 and 6 ). The remaining components  420 ,  430 ,  440 , and  450  of assembly  400  are preferably made of metal. 
     The shape of guide structure  440  warrants the following further discussion. The distal-most portion  442  of structure  440  may be a tube. The proximal-most portion  444  of structure  440  may be U-shaped, open at the top as viewed in  FIG. 7 . The portion of structure  440  between elements  442  and  444  may comprise four strips  446   a - d  (see  FIG. 8 ) that form an annular array around delivery tube  500 . 
     The distal (apex) end of V  110  is attached to the side wall of tube  420 . The arms of V  110  may not actually come together at the apex, but rather tube  420  may effectively provide the apex of that V. Thus the distal end of each arm of V  110  may be connected to a respective opposite side of the wall of tube  420 , with that tube providing the apical connection between the arms. 
     The proximal (apex) end of V  130  may be similarly connected to the wall of delivery tube  500  (see again  FIG. 8 ). Each arm of V  130  extends out of a respective opposite side of guide structure  440  between a respective pair of the strips  446  of that structure. For example, as viewed in  FIG. 8 , the left-hand arm of V  130  extends out between strips  446   a  and  446   b , and the right-hand arm of V  130  extends out between strips  446   c  and  446   d . As in the case of V  110 , the arms of V  130  may not actually come together at the apex of that V, but instead the distal end of tube  500  may effectively form the apex of V  130 . 
     V  120  straddles assembly  400 . The apex of V  120  is toward the top as viewed in  FIG. 7 . 
     Assembly  400  is movable axially (longitudinally) relative to catheter  300 . This allows assembly  400  to be extended from the distal end of catheter  300  or retracted into the catheter. Tube  500  is movable axially (longitudinally) relative to assembly  400  and catheter  300 . For example, proximal retraction of tube  500  relative to assembly  400  from the position shown in  FIG. 7  tends to straighten and collapse Vs  110  and  130 . Collapsing Vs  110  and  130  also collapses V  120 . Then further proximal retraction of tube  500  together with assembly  400  draws everything into the distal end of catheter  300 . This folds already-collapsed V  120  down onto assembly  400  for entry into the distal end of the catheter. Reversing the above-described relative motions allows the structure to deploy (resiliently in the case of Vs  110 ,  120 , and  130 ) to the condition shown in  FIG. 7 . 
     The condition of the apparatus shown in  FIG. 7  corresponds to the condition of structure  100  in  FIGS. 3 and 4 , assuming that everything else in  FIG. 7  has been positioned in the patient as shown in  FIGS. 5 and 6 . Thus, as described above in connection with  FIGS. 3 and 4 , deployed V  110  in  FIG. 7  centers structure  100  in PFO tunnel  50 ; deployed V  120  in  FIG. 8  cooperates with deployed V  110  to engage the limbus  60  of secundum  30  and thereby prevent further distal motion of both structure  100  and assembly  400  relative to limbus  60 ; and deployed Vs  110  and  120  cooperate with the adjacent tissue to prevent structure  100  and assembly  400  from rotating about a longitudinal axis of those components (i.e., a left-right axis in  FIG. 7 ). Thus the features that have been described up to this point substantially fix components  100  and  400  in a very secure and stable way at a particular location relative to PFO  50 . 
     It is now meaningful to describe a possible further feature of the invention as follows. After the apparatus is in place in the patient as described above in connection with  FIG. 7 , tube  500  can be pushed farther in the distal direction relative to assembly  400 . At first the distal portion of tube  500  remains straight. Eventually, however, the distal end of tube  500  contacts tube  442 , which it cannot pass through. Further distally-directed pushing on tube  500  causes the distal portion of that tube to buckle as shown in  FIG. 9 . The extreme distal end of tube  500  cannot get away from assembly  400  because it is trapped by the arms of V  130  passing between strips  446   a  and  b  on one side and strips  446   c  and  d  on the other side. Also, just as the distal end of tube  500  is too large to pass through cylinder  442 , it is also too large to pass between strips  446   a  and  446   d . The distal portion of tube  500  can, however, buckle upwardly as viewed in  FIG. 9  out of the top of structure  400 . This is possible because component  444  has a U shape that is open at the top, and because the space between strips  446   b  and  446   c  is great enough to permit tube  500  to deflect upwardly out of structure  400 . Thus it will be seen that structure  400  causes the distal portion of tube  500  to buckle, but only permits buckling in one direction, i.e., upwardly as viewed in  FIG. 9 . 
     It will be noted that V  130  changes shape somewhat during the above-described further distal motion and buckling of tube  500 , but this does not significantly alter the disposition of Vs  110  and  120 . Thus Vs  110  and  120  continue to hold the distal portion of the apparatus at the previously described location in the patient and with the previously described orientation relative to the patient&#39;s tissue structure. 
     The result of the above-described constrained buckling of tube  500 , together with the other constraints described above (i.e., Vs  110  and  120  substantially fixing the location and orientation of structure  400  relative to the patient&#39;s tissue structure), is that the distal end of tube  500  in  FIG. 9  is substantially perpendicular to septum primum  40  like axis  80  in  FIGS. 1 and 2 . The distal end of tube  500  is also at the location shown for axis  80  in  FIGS. 1 and 2 . Tube  500  can therefore be advantageously used to guide tissue piercing apparatus to and through primum  50  at the location and in the direction of axis  80  in  FIGS. 1 and 2 . The continued presence of V  110  in PFO tunnel  50  helps to provide the apparatus with the reaction force that may be needed to get the tissue piercing structure through the primum. Such reaction force may also be provided by continued contact of catheter  300  with inferior vena cava wall  70 . The piercing can be done in an extremely controlled way to ensure that the piercing instrument does not suddenly break through the primum and go too far across left atrium  20  to a point where it may cause undesirable damage to other tissue. (For completeness, a piercing structure  600  is shown in dotted lines in  FIG. 9  extending distally from the distal end of structure  500 .) 
     If it is desired to change the location relative to limbus  60  of the distal end of buckled tube  500 , that can be done by shifting the proximal end of tube  442  to the left relative to the location shown in  FIGS. 7 and 9 . This is a design change, not an operational change, in embodiments of the type illustrated herein. 
     If the patient does not have a PFO, limbus  60  may still be an accessible feature of the patient&#39;s anatomy. To make use of that feature in much the same way as described above for PFOs, components  410 ,  420 ,  430 , and  110  may be variously shortened or eliminated. The apparatus may then still be able to engage limbus  60  in somewhat like the fashion described above, with many of the attendant advantages described above. Thus use in connection with a PFO is only illustrative, and the invention may be alternatively used in connection with any other suitable tissue structures, with possible modifications of the apparatus that are appropriate for such other tissue structures. 
       FIG. 10  shows an alternative embodiment with many of the attributes that are described above but that may be usable with anatomies that are similar to or different from those shown as described above. Reference numbers that have been used above are used again in  FIG. 10  for the same or generally similar components. 
     In  FIG. 10 , structure  400  is selectively extendable from catheter  300 . Structure  400  carries resiliently expandable structure  100 . When structures  100  and  400  are inside catheter  300 , structure  100  is collapsed by the catheter. When structures  100  and  400  are extended from catheter  300  (as shown in  FIG. 10 ), structure  100  resiliently expands to the relatively large two-dimensional shape shown in  FIG. 10 . This two-dimensional shape of structure  100  may be held relatively flat against an adjacent tissue surface (e.g., primum  40 ) by having the distal-most portion of structure  100  engaged under limbus  60  (even if the patient does not have a PFO) and/or by contact of catheter  300  with inferior vena cava wall  70 . (A back side of deployed structure  500  bearing against an opposite tissue surface may later also help to hold structure  100  in the desired position against the adjacent tissue surface.) Pushing structure  100  against the underside of limbus  60  (even in the absence of a PFO) may also help to position the distal end of the apparatus both axially and laterally (i.e., side-to-side in the plane defined by deployed structure  100 ). 
     After structure  100  has been deployed as described above, structure  500  may be pushed distally relative to the other components. Structure  400  includes a component  440  that prevents the distal end of structure  500  from going beyond a desired point within deployed structure  100 . Distal pushing of structure  400  therefore causes its distal portion to buckle as shown in  FIG. 10 . This aims the distal end of structure  400  toward a desired tissue location and with a desired angle relative to the surface of that tissue. Tissue engaging (e.g., penetrating) structure  600  can then be extended distally from structure  500  as shown in  FIG. 10  to engage (e.g., penetrate) the tissue at the desired location and with the desired angle. 
     Deployment of the  FIG. 10  apparatus is reversible. Structure  600  can be pulled back into structure  500 . Structure  500  can be pulled back to straighten it. All of structures  100 ,  400 , and  500  can be pulled back into catheter  300 . 
     It will be noted that the apparatus of this invention can attain and maintain a desired position in a patient&#39;s anatomy without the necessity for tissue penetration. (Of course, tissue penetration may come later by other components such as  600 .) Moreover, this can be done in a relatively open part of the anatomy such as the right atrium without filling that anatomy with any large structure and without interfering with continued normal functioning of the anatomy while the apparatus is present in the anatomy. 
     It will be understood that the foregoing is only illustrative of the principles of the invention, and that various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention. For example, the materials that are mentioned above for certain components are only illustrative, and other suitable materials can be used instead if desired.