Abstract:
Methods and apparatus for providing transapical access to a heart chamber for performing an intra cardiac procedure are described. The apparatus include a helical needle driver, a dilator, a straight access needle, and optionally a guidewire. After entering the heart chamber with the straight access needle, the helical needle driver is used to place a helical suture within the myocardium. After removing the needle driver, the dilator is advanced through the pre-placed helical suture, dilating both a passage and the circumscribing suture. After performing procedure, the pre-placed suture may be closed by proximally retracting an external end of the suture.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of prior provisional application No. 61/398,485, filed on Jun. 26, 2010, and of prior provisional application No. 61/402,042, filed on Aug. 23, 2010, the full disclosures of which are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates generally to medical apparatus and methods. More particularly, the present invention relates to methods and apparatus for providing transapical access to a heart chamber to facilitate performing various procedures within the heart chamber, such as heart valve replacement, valve repair, atrial septum repair, aneurysmectomy, and the like. 
         [0004]    Heart valve replacement and repair on beating hearts are typically performed via a transvascular or a transapical approach. Of particular interest to the present invention, transapical access is typically established via an intercostal incision and placement of a relatively large cannula to provide access to the apex of the heart. Conventional surgical tools are then used through the cannula to form an incision into the heart to allow passage of the interventional tools used for the heart valve replacement, repair, or other procedure. Frequently, a purse string suture is pre-placed at the site of the incision to facilitate closure after the procedure is complete. 
         [0005]    The need to use conventional surgical tools for making the incision through the apical region into the heart chamber requires that a relatively large access port be placed through the intercostal space, typically between the fourth and fifth ribs. The incision is typically 4 or 5 cm in length, and such incisions in the abdomen are very painful to the patient. 
         [0006]    For these reasons, it would be desirable to provide improved apparatus and methods for both accessing a heart for transapical penetration and for closing the penetration after the related procedure has been completed. Such apparatus and methods would preferably require a smaller intercostal incision than has often been necessary in the past, and in particular, it would be desirable if the incision were below 5 cm, preferably below 4 cm, and still more preferably below 3 cm, or less. Methods and apparatus should further provide for both simplified access and closure protocols, should present minimum risk to the patient, be economical, and be relatively uncomplicated for use by the physician. At least some of these objectives will be met by the inventions described below. 
         [0007]    2. Description of the Background Art 
         [0008]    U.S. Patent Publ. Nos. 2011/0015728; 2011/0004235; and 2009/0287183 describe devices for transapically accessing a heart chamber for performing valve replacement and other procedures. U.S. Patent Publ. No 2010/0268253 describes a self-closing structure that can be disposed about a transapical access site. U.S. Pat. No. 4,204,541, describes a helical needle for performing vertical suturing in tissues including cardiac and live tissue. U.S. Pat. Nos. 7,758,595; 7,637,918; 5,545,148; and 5,356,424; and U.S. Patent Publ. Nos. 2009/275960; 2008/275473; 2006/253127; and 2006/212048 describe other suturing devices with helical needles. 
       SUMMARY OF THE INVENTION 
       [0009]    In a first aspect of the present invention, a method for transapical access to a heart chamber comprises advancing a helical needle through the myocardium to position a suture through an apical region of the heart, withdrawing the helical needle leaving the suture in place in the myocardium in a helical pattern, and thereafter dilating a passage through the helical suture into the heart chamber. The pre-placed suture is then available for closing subsequent incisions into the heart by simply drawing proximately on the suture to close such incisions. The suture is typically self-anchoring, e.g. having anchoring barbs or a T-bar at or near its distal end, and placement can be accomplished using relatively small tools, typically through an intercostal incision below 3 cm, often below 2 cm, and in some cases below 1 cm. Methods are also suitable for performing on a beating heart, although they could be used in stopped heart procedures as well. In exemplary embodiments, tension is maintained on the pericardium to stabilize the heart while the helical needle is being advanced and/or a dilator is being advanced through the helical suture (described in more detail below). 
         [0010]    In an exemplary embodiment of the method of the present invention, the helical needle is first passed through the pericardium surrounding the heart, and the helical needle is then drawn proximately to tension the pericardium and stabilize the heart. The helical needle is then advanced into the myocardium while the tension is maintained on the pericardium. In addition or as an alternative to using the helical needle for applying traction on the pericardium, a shaft or other component of the access tool could also be provided with barbs, expanding elements, or the components suitable for engaging the pericardium and applying traction while the needle is being advanced. 
         [0011]    In most procedures, prior to introducing the helical needle, a straight needle will be advanced through the apical region of the heart to establish an initial tissue tract through the myocardium and to confirm the correct entry point and orientation. Optionally, the needle may be used to place a guide wire, but usually the needle itself will be used as a guide for the introduction of the helical needle deployment device, as described in more detail below. In such cases, the needle may have to have a proximal hub that can be removed prior to advancement of the helical needle assembly thereover. Alternatively, the needle shaft could be long enough to allow the helical needle assembly to be pre-loaded on the straight needle prior to accessing the heart chamber. 
         [0012]    In many cases, the present invention will use a single helical needle in order to place a single helical suture. In other embodiments, however, it may be desirable to deploy multiple helical needles, usually simultaneously using the same needle deployment shaft. In some instances, two or more helical needles may be coaxially nested with one helical needle having a smaller diameter and being disposed radially inwardly of an outer helical needle. In other instances, the two or more helical needles may be located in a common cylindrical envelope. In such cases, the needles may have penetrating tips which are rotationally offset and/or axially offset from each other. 
         [0013]    The suture will usually be placed within the myocardium and will not extend into the heart chamber (beyond the myocardium). In such cases, use of a suture having self-deploying barbs at its distal end will be particularly useful. The barbs project partially outside of the needle as the needle is rotationally advanced into the tissue. As soon as the rotational advancement of the helical needle is stopped and reversed, however, the barbs will anchor in the tissue and hold the distal end of the suture in place as a helical needle is counter-rotated and removed from the tissue. In other instances, however, it may be desirable to advance the suture all the way into the heart chamber. In such cases, some other self-deploying anchor, such as a T-bar will find use. 
         [0014]    Methods for establishing transapical access in accordance with the present invention will find use with a variety of intracardiac procedures that may be performed on beating hearts. In such procedures, one or more tools are introduced through the dilated passage which has been formed through the myocardium while the helical suture remains in place surrounding the tool as the tool is advanced. A cardiac procedure will be performed with the tool, and the tool(s) then removed from the dilated passage after the procedure has been completed. After the tools and any devices used for access have been removed, the dilated passage may be closed by drawing on the suture in a proximal direction, closing the helical suture loops which were pre-placed as described above. The methods herein are suitable for a wide variety of intracardiac procedures including valve replacement, valve repair, left atrial appendage closure, cardiac oblation, closure of an atrial septal defect, closure of a patent foramen ovale, and the like. 
         [0015]    In a second aspect of the present invention, a system for establishing transapical access through myocardial tissue is provided. The system comprises a helical needle driver having a cylindrical shaft having a distal end, a proximal end, and a central passage extending between said ends. A helical needle is coupled to the distal end of the shaft, and suture is releasably carried by the helical needle. The system further comprises a dilator having a width greater than that of the cylindrical shaft, where the dilator is adapted to exchanged for the helical needle driver to enlarge a passage through the helical suture which is left in place in the myocardium. Usually, the dilator will be advanced over the straight needle or optionally over a guidewire deployed by the straight needle. The system may optionally further include a sheath or a trocar for establishing access to the pericardium from an intercostal access site or optionally from a subxiphoid access site. 
         [0016]    In a simpler embodiment, the helical needle driver may include just the helical needle (or multiple needles as described below in connection with the methods of the present invention), fixedly attached to the distal end of the cylindrical shaft so that the needle is advanced through the tissue by rotating the entire cylindrical shaft. Preferably, however, the helical needle driver will further comprise a mechanism for rotating the helical needle relative to the cylindrical shaft to advance the helical needle through tissue and relative to the shaft itself. An exemplary driver mechanism will comprise a coaxial inner cylinder or tube which carries the helical needle(s) at its distal end. The needles may then be advanced relative to the outer cylindrical shaft by rotating and advancing the intertubular shaft relative to the outer shaft, for example using a threaded drive assembly in the handle of the shaft assembly. 
         [0017]    In most instances, the helical needle is hollow and the suture is received into the hollow passage of the needle at least over a portion of the needle length. In other instances, however, it may be possible to serve or wrap the suture over the exterior of the needle and/or within recesses formed in the needle surface (where the needle need not be hollow). For example, the suture may be wrapped around the exterior surface of the needle so that the suture is left in a loose pattern within the myocardium, with excess suture length available for expansion or elongation when the suture is radially expanded by the dilator. 
         [0018]    The system may optionally include other components, such as the straight needle used for initially accessing the heart chamber through the myocardium, a guidewire to optionally be placed using this straight needle, and the like. In another case, the cylindrical shaft of the needle deployment tool will be advanced over the needle and/or over the guidewire in order to establish the initial penetration through the myocardium. Another option is the use of a cahter or other guiding apparatus having a balloon or other anchor at its distal end where, after the insertion of its distal tip to the ventricle, the anchor will be deployed and the guiding apparatus retracted to provide a counter force for the dilator insertion. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]      FIG. 1  illustrates a system for establishing transapical access to a heart chamber constructed in accordance with the principles of the present invention and including a helical needle driver, a dilator, a straight needle, and optionally a guidewire. 
           [0020]      FIGS. 2A and 2B  illustrate the helical needle driver of  FIG. 1  in detail, with the helical needle retracted in  FIG. 2A  and the helical needle advanced in  FIG. 2B . 
           [0021]      FIGS. 3A and 3B  illustrate a barbed suture anchor and a T-bar suture anchor, respectively, emerging from distal end of a helical needle. 
           [0022]      FIGS. 4A and 4B  illustrate a dual needle embodiment having the sharpened needle tips axially offset. 
           [0023]      FIGS. 5A and 5B  illustrate a dual needle embodiment having the sharpened needle tips being 180° offset. 
           [0024]      FIGS. 6A and 6B  illustrate a dual needle embodiment having a larger diameter outer helical needle and a smaller diameter inner helical needle. 
           [0025]      FIGS. 7A-7E  illustrate exemplary dilator contractions in accordance with the principles of the present invention. 
           [0026]      FIGS. 8A-8J  illustrate an exemplary transapical access procedure and intervention performed in accordance with the principles of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0027]    Referring to  FIG. 1 , a system  10  constructed in accordance with the principles of the present invention includes a helical needle driver  12 , a dilator  14 , a straight needle  16 , and optionally a guidewire  18 . The components of the system will typically be packaged together in conventional packaging, such as plastic trays, sterilized bags, boxes, and the like. The relative dimensions of each of the components will be selected to be compatible with each other. For example, both the helical needle driver  12  and dilator  14  will be sized to be advanced over either the needle  16  (in embodiments where the needle will be used as the guide for introducing these tools through the myocardium), or over the guidewire  18  (in embodiments where the driver  12  and dilator  14  will be advanced over the guidewire). 
         [0028]    Referring now to  FIGS. 2A and 2B , the helical needle driver  12  comprises a shaft assembly  20  having a distal end  22  and a proximal end  24 . A drive handle  26  is attached to the proximal end  24  of the shaft assembly  20  and includes an inner threaded body  28  ( FIG. 2A ) and an outer rotatable member  30 . The outer rotatable member  30  can be rotated over the inner threaded body  28  so that a helical needle  36  can be selectively retracted and advanced as shown in  FIGS. 2A and 2B , respectively. 
         [0029]    The inner threaded body  28  of the drive handle  26  is fixedly attached to an outer cylindrical tube  32  of the shaft assembly  20  while the outer rotatable member  30  is attached to an inner tubular member  34  ( FIG. 2A ). In this way, rotation of the outer rotatable member  30  over the inner threaded body  28  both rotates and advances (or retracts) the helical needle  36  which is fixedly attached to a distal end of the inner tubular member  34 . Although shown as a simple helical needle, the needle in the helical needle driver can have any of the configurations shown in FIGS.  3 A/B through  6 A/B described below. 
         [0030]    The helical needle driver  12  also includes a central tube  38  which extends the entire length thereof and which provides a central passage way or lumen for advancement of the driver over the straight needle  16  and/or guidewire  18 , as described in more detail below. 
         [0031]    Referring to  FIGS. 3A and 3B , suture  40  will typically be stowed or held within a hollow passageway through at least a distal portion of the needle  36 . The suture will extend out of a small hole or port  42  disposed near the sharpened tip  44  of the needle. The suture will have an anchor formed at or over its exposed end. The anchor may be a barbed structure  48 , as show in  FIG. 3A , a T-Bar structure  50 , as shown in  FIG. 3B , or any one of a variety of other structures which allow the suture to be advanced into the tissue and which anchor within the tissue when the needle is counter-rotated and withdrawn from the tissue. The suture may be configured and/or deployed to accommodate expansion as the dilator is advanced through the helical “cage” formed after the suture is deployed. For example, the suture could be “stretchable” along its length so that the diameter of the helical cage can increase as the dilator is advanced. Alternatively, excess suture length can be stowed in and/or over the helical needle so that extra lengthing capacity is provided when the suture is left in the tissue. 
         [0032]    Referring now to FIGS.  4 A/B through  6 A/B, a variety of dual needle configurations will be described. An advantage of utilizing two, three, or even more helical needles is that a greater density of suture can be left in place in order to provide for tighter closure and constriction of the dilated passage formed through the myocardium. In FIGS.  4 A/B, a pair of helical needles  16 ,  62  are nested so that they lie within the same cylindrical envelope while having distal tips  64  and  66 , respectively, which terminate in an axially spaced-part pattern. Needles  70 ,  72 , as shown in  FIGS. 5A and 5B , are also nested so that they lie in the same cylindrical envelope, but the sharpened distal tips  74 ,  76 , respectively, terminate at locations 180° opposed to each other. As a third alternative, helical needles  80 ,  82 , as illustrated in FIGS.  6 A/B, may be arranged in a cylindrically nested configuration where an outer helical needle  80  has a larger diameter than an inner helical needle  82 . The sharpened distal tips may terminate 180° in opposition as illustrated, or could terminate in axially spaced-apart configurations (not illustrated). 
         [0033]    Referring now to  FIGS. 7A through 7C , a dilator  14  preferably comprises a body formed from an elastomeric or other compressible material over at least its distal portion. For example, the elastomeric material may be formed into an outer tubular component  90  formed over an inner rigid tubular support  92 , shown in  FIG. 7A . The tube has an inner lumen  93  suitable for receiving and advancement over the access needle and/or a guidewire present in the initial tissue tract being dilated. Cutting blades  94  may be attached to a distal end of the inner support tube  92 , and such blades may be recessed within protective grooves  96  as shown in  FIG. 7B  (as shown for a two-bladed configuration) and  FIG. 7C  (as shown for a four-bladed configuration). In this way, the cutting edges of the blades  94  will be protected from inadvertently cutting tissue but will be exposed when the dilator tip is engaged against particularly strong tissue or membranes which resist expansion and will require cutting, such as the pericardium. Optionally, the obturator may comprise an outer sleeve  93  and removable obturator  95  ( FIG. 7D ) or may have external threading  97  ( FIG. 7E ) to assist in advancement through the myocardium. 
         [0034]    The blades  94  need to have widths which span the entire diameter of the dilator  14 . For example, a typical dilator diameter will be 1 cm, and the blades will typically span only 2 mm to 6 mm. Alternatively or additionally, the dilator may have external threads which allow the dilator to be rotated about its axis to enhance advancement through the tissue tract. 
         [0035]    Referring now to  FIGS. 8A through 8J , an exemplary protocol for transapically accessing a heart chamber and performing an intra cardiac procedure according to the principles of the present invention will be described. The relevant patient anatomy is illustrated in  FIG. 8A  where a transapical region TA of a patient&#39;s heart H is protected behind the patient&#39;s ribs. Access will generally be performed through the intercostal space between rib R 4  and rib R 5 . 
         [0036]    Initially, the straight needle  16  will be penetrated intercostally between ribs R 4  and R 5  so that the sharpened tip of the needle can enter the heart at the transapical region TA, as shown in  FIG. 8B . Usually, the straight needle will be passed through a small intercostal incision, e.g., less than 3 cm, usually less than 2 cm, and often about 1 cm. To assist in guiding, the straight needle may incorporate ultrasonic or optical imaging. Alternatively, a thoracoscope or other endoscope could be deployed through a separate incision to allow visualization. 
         [0037]    After advancing the needle through the myocardium into the left ventricle of the heart, the needle hub  17  will be removed and the helical needle driver  12  will be advanced over the needle  16 , as shown in  FIG. 8C . The shaft assembly  20  of the needle driver  12  will be advanced until the distal tip of the shaft engages the pericardium surrounding the myocardium of the heart. 
         [0038]    Referring now to  FIG. 8D , the helical needle  36  will be advanced from the distal end of the shaft assembly  20  to initially penetrate the pericardium P. Once the needle has penetrated the pericardium, the helical needle driver  12  will be proximally retracted to apply tension to the pericardium which will help stabilize the heart and facilitate needle entry into the heart. 
         [0039]    As illustrated in  FIG. 8E , the helical needle  36  may be rotated and advanced into the myocardium M while the pericardium P remains under traction. Straight needle  16  also remains in place to help guide the helical needle  36 . 
         [0040]    Preferably, the needle  36  will not be advanced fully into the left ventricle and, instead, needle rotation will stop and be reversed in order to leave the helical suture in place with the barb anchor  48  within the myocardium as show in  FIG. 8F . At this point, the helical needle driver will be completely withdrawn, leaving the straight access (guiding) needle  60  and helical suture  40  in place. 
         [0041]    Next, as shown in  FIG. 8G , the dilator  14  will be advanced over the needle  16  until its distal tip reaches the pericardium P. As the dilator  14  is advanced through the pericardium, the recessed blades  94  will be exposed as the elastomeric material surrounding them is compressed by the pericardium. The blades  94  help the dilator  14  pass through the pericardium, and the dilator is then able to enter the myocardium M as shown in  FIG. 8H . As the myocardium M is not as fibrous and difficult to penetrate as the pericardium is, the elastomeric material will recover from compression and the blades  94  will again be recessed within the tip of the dilator  14  as the tip advances into the left ventricle of the heart. The blades  94  are optional, particularly if the pericardium is pre-cut prior to advancing the dilator therethrough. Blades are usually not needed to advance the dilator through the myocardium. 
         [0042]    As the dilator  14  passes through the helical suture  40 , the suture is radially expanded. Typically, extra lengths of suture will be left in place by the helical needle in order to facilitate radial expansion. For example, the suture  40  may be stowed within a central passage of the needle in a serpentine or compacted configuration where tension on the suture will extend its length. Further optionally, the needle, guidewire, or other guiding apparatus (not illustrated) may be provided with a balloon or other deployable anchor to allow a counter traction on the myocardium as the dilator is advanced. 
         [0043]    After the dilator  40  has been passed through the myocardium M, as shown in  FIG. 8H , the dilator will be removed and a working cannula WC having a hemostatic value HV is placed over the needle  16  and the needle removed as shown in  FIG. 8I . The working cannula provides access for working tools intended to perform any particular intra cardiac procedure desired. An exemplary tool T is illustrated, but it will be appreciated that specific tools will be associated with specific procedures. Optionally, the working cannula can be part of the dilator where a central member (obturator) of the dilator is removed to leave an outer sleeve in place as the cannula. 
         [0044]    Finally, after the intra cardiac procedure is complete and the working cannula WC and all tools T removed, the suture  40  may be proximately retracted to close the helical suture loops within the myocardium to close the incision I as shown in  FIG. 8J . The suture could be tied off, but more usually, a suture lock  100  will be advanced over the suture to hold the suture loops and prevent the incision I from reopening. 
         [0045]    While the above is a complete description of the preferred embodiments of the invention, various alternatives, modifications, and equivalents may be used. Therefore, the above description should not be taken as limiting the scope of the invention which is defined by the appended claims.