Abstract:
In a transseptal crossing needle device for inserting an outer sheath through a septum, an inner dilator sheath is received within the outer sheath and a needle having a curved end portion adjacent a tip of a tip portion of the needle is provided, the needle being received in the inner dilator sheath. The needle tip portion comprises an angled transverse end surface terminating at said tip and slanting away from an inner concave curved wall of said inner sheath curved by the needle curved end portion, the needle tip being spaced not only away from said inner concave curved wall of said inner sheath but also away from an inner convex curved wall of said inner sheath opposite said concave wall to reduce or eliminate skiving of material from the concave and convex inner walls of the inner sheath.

Description:
BACKGROUND 
       [0001]    Transseptal crossing, puncture, or catheterization is a means of gaining access to the left atrium  11  from the right atrium  12  of the heart  10 . These chambers of the heart are shown in prior art  FIG. 1  but since the patient is being viewed from the front, the left atrium  11  is shown on the right side and the right atrium  12  is shown on the left side in the drawing figure. This transseptal crossing, puncture, or catheterization was first described independently by Ross and Cope in  1959  in the article “Transseptal Catheterization in 2010: Crossing into a New Decade”, EP Lab Digest, February 2010. In  FIG. 1  one may observe a transseptal crossing needle device  13  having an outer sheath  14 , an inner dilator sheath  15 , and a hollow needle  16  positioned within the inner sheath  15 . The needle  16  has a curved portion  24  progressing towards a tip portion  16 A. The inner sheath  15 , as most clearly shown in expanded prior art view  FIG. 2 , has a partial conical tip tapering portion  15 A and also is curved near it&#39;s end by the forces exerted by the needle curved portion  24 . The hollow needle  16  has a transverse cut tip portion  16 A terminating in a tip  16 AB at the end of upwardly sloping transverse end surface  16 AA. Note that this surface  16 AA slopes towards an upper concave curved inner wall  15 B of the end portion of the inner sheath  15  and away from a lower convex curved inner wall  15 A. Over the past 10 years or so, the number of transseptal crossings being performed has increased dramatically, driven mostly by the increase in atrial fibrillation (AF) ablation procedures within electrophysiology. This remains the predominant use of transseptal crossing devices. However, new minimally invasive percutaneous procedures related to structural heart are also being developed that use these devices. These procedures include the closure of atrial septal defects, left atrial appendage closure device implementation, and left ventricular assist device implantation. 
         [0002]    Transseptal crossing across what is known as the septum  17  (fossa ovalis) as shown in  FIG. 1  to gain access to the left atrium  11  is acknowledged as a critical and very dangerous part of all of the above procedures. Clinical guidelines support the use of multiple visualization checks when conducting this procedure with many physicians using a combination of fluoroscopy, echocardiography, pacing, and contrast injection, along with their own judgment and experience. For a number of different procedures, access to the left atrium  11  via the septum  14  (fossa ovalis) as described above is required. These procedures include mitral valve repair, mitral valvoplasty, atrial fibrillation ablation, and closure of left atrial appendage repair or closure. 
         [0003]    Referring to  FIG. 1 , according to the prior art procedure the tapered conical end portion  15 A of the inner dilator sheath  15 , and more particularly the leading end  15 AA, is moved down the septum  17  as shown by the arrow  18  until it reaches the relatively thinnest part of the septum  17 . Thereafter the hollow needle  16  is pushed beyond the inner sheath end  15 AA and penetrates through the septum  17 . Thereafter the inner sheath  15  functioning as a dilator dilates with its conical end portion  15 A the opening provided by the needle and pushes through, thus dilated the needle opening. Thereafter the outer sheath  14  is pushed along the inner sheath  15  through the dilated opening  17 A. As shown in  FIG. 4 , the needle  16  and inner dilator sheath  15  are then withdrawn, leaving only the outer sheath  14  in the opening  17 A, which is then available for use with medical instrumentation to be inserted into the left atrium  11  as described above. 
         [0004]    The tip portion  16 A of the needle  16  penetrates the septum  14  using ultrasound visualization. 
         [0005]    Prior art  FIG. 3  illustrates how the physician manipulates the inner and outer sheaths  15  and  14 , and needle  16 , for the above-described procedure. Initially before introduction into the human body, the needle  16  is pushed through the inner dilator sheath  15  until the tip portion  16 A with tip  16 AB is positioned near the tapered end portion  15 A as shown in  FIG. 2 . A needle handle  19  firmly attached to an end of the hollow needle  16  is provided for manipulating the needle through the inner sheath  15 . The needle handle  19  has a plurality of finger grip knurls  20 . A leading end of the handle  19  has a pointing arrow  21  to indicate a rotational position of the needle  16 , and particularly of the needle curved portion  24  leading to the tip portion  16 A at the end of the hollow needle  16 . The steel needle is pre-stressed into a curve at the curved portion  24  which causes a bending of the flexible inner sheath  15  and outer sheath  14  where the needle curved portion  24  is present. 
         [0006]    Rearwardly of the finger knurls  20  is located a stop cock  22  for allowing in flow a liquid such as a dye introduced through a flexible hose  23  for delivery through the needle. 
         [0007]    As illustrated in  FIG. 3 , the needle  16  passes through an inner dilator sheath handle  26  firmly attached to the inner dilator sheath  15 . A knurled finger grip  26 A is integrally formed at the needle entry end of the inner sheath handle  26  for finger gripping. 
         [0008]    The opposite end of the inner sheath handle  26  butts against an outer sheath handle  27  having a knurled finger grip portion  27 A. The outer sheath handle  27  is rigidly attached to the end of the outer sheath  14  for manipulation thereof. A hose  27 B allows introduction of a fluid such as saline solution into the outer sheath  14  which surrounds the inner sheath  15 . 
         [0009]    The outer sheath  14  with the inner sheath  15  and needle  16  enter an outer wall of the human body  28  as shown at  28 A and then are fed up to the heart through an artery, for example, and then to the septum  17  within the heart as explained in connection with  FIG. 1  so as to create the desired diluted aperture  17 A in the septum  17  as described above. 
         [0010]    After the conical portion  16 A of the inner dilator sheath  16  has been located as described above at the septum  17  in  FIG. 1 , then the physician pushes on the needle handle  19  to close the gap G between the leading end at arrow  21  of the handle  19  and the back surface of the inner sheath dilator handle  26 . This causes the tip  16 A of the needle to push out through the end  15 AA of the inner sheath  15 A to penetrate through the septum  17  such that thereafter a small portion of the needle at it&#39;s tip portion now lies on the opposite side of the septum within the left ventricle  11 . 
         [0011]    During introduction and movement of the tip portion  16 A having the transverse upwardly slanting angled end surface  16 AA as shown in  FIG. 2  to form the tip  16 AB, shavings  29  can be scraped off by skiving at the upper convex curved inner wall  15 B of the inner sheath  15  by the tip  16 AB running along this convex curved inner wall  15 B. This is undesirable and a disadvantage of this prior art device. 
         [0012]    Another disadvantage of the prior art system is that presently the skill of the operator and “feel” are critical determining factors in the successful placement of the needle  16  and crossing of the fossa  14 . Significant training is required in order for a physician to complete this procedure correctly. 
       SUMMARY 
       [0013]    It is an objective to eliminate the creation of shavings by the above-described skimming and also to provide improved safety and ease of delivery of the needle of the transseptal crossing needle device for penetration of the septum as described above. 
         [0014]    In a transseptal crossing needle device for inserting an outer sheath through a septum, an inner dilator sheath is received within the outer sheath and a needle having a curved end portion adjacent a tip of a tip portion of the needle is provided, the needle being received in the inner dilator sheath. The needle tip portion comprises an angled transverse end surface terminating at said tip and slanting away from an inner concave curved wall of said inner sheath curved by the needle curved end portion, the needle tip being spaced not only away from said inner concave curved wall of said inner sheath but also away from an inner convex curved wall of said inner sheath concave wall to reduce or eliminate skiving of material from the concave and convex inner walls of the inner sheath. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  is a cross-sectional side view of a heart with a prior art transseptal crossing needle device having a needle for puncturing through the septum of the heart; 
           [0016]      FIG. 2  is a cross-section enlargement of the prior art device of  FIG. 1  at an end of an inner sheath touching against the septum and with a needle having a needle tip positioned slightly rearwardly of the end of the inner sheath; 
           [0017]      FIG. 3  is a side view of the prior art transseptal crossing needle device, a portion of which is shown in  FIG. 1 ; 
           [0018]      FIG. 4  is a cross-sectional side view of the septum with the prior art outer sheath of the transseptal device crossing through the septum; 
           [0019]      FIG. 5  is a side cross-sectional view of an exemplary embodiment according to the invention of an improved needle tip portion; 
           [0020]      FIG. 6  is a side view of the improved needle tip after it has passed through the septum and also showing first and second echogenic markers for ultrasound visualization at and near the improved tip; 
           [0021]      FIG. 7  is a side view of the improved transseptal crossing needle device having not only the improved tip and markers shown in  FIGS. 5 and 6 , but also having a first embodiment of a spacing device between the needle handle and the inner sheath handle in a gap G also shown in prior art  FIG. 3 ; 
           [0022]      FIG. 8  shows an end view of the prior art spacer device of  FIG. 7 ; 
           [0023]      FIG. 9  shows a second embodiment of a spacer device between the needle handle and the inner sheath handle located in a bigger gap G′ than the gap G shown in prior art  FIG. 3 ; 
           [0024]      FIG. 10  is an end view of the second embodiment of the spacer device shown in  FIG. 9  looking toward the needle handle; 
           [0025]      FIG. 11  is a third embodiment having first and second visible markers located in the gap G shown in prior art  FIG. 3 ; and 
           [0026]      FIG. 12  shows the first and second echogenic markers previously described in connection with  FIG. 6  but in an enlarged view. 
       
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0027]    For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the preferred exemplary embodiments/best mode illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, and such alterations and further modifications in the illustrated embodiments and such further applications of the principles of the invention as illustrated as would normally occur to one skilled in the art to which the invention relates are included herein. 
         [0028]    An exemplary embodiment is shown in  FIG. 5  of an improved needle tip portion  29  for the improved transseptal crossing devices  32  show in  FIG. 7, 33  shown in  FIGS. 9, and 34  shown in  FIG. 11 . Hereinafter, when describing the improvements in  FIGS. 5-12  of the improved transseptal needle device embodiments, components which are unchanged relative to the prior art transseptal needle device shown in  FIG. 3  have retained the same reference numerals as in  FIG. 3 . 
         [0029]    As shown in  FIG. 5 , the improved tip portion  29  has its transverse end surface  29 A downwardly sloping towards the convex curved inner wall  15 C of sheath  15  as it proceeds to the tip  29 AB. This slope is opposite to the slope of the prior art tip portion  16 A which slopes upwardly towards the concave inner wall  15 B of the sheath. This eliminates the shavings  29  caused by skiving since the leading tip  29 AB does not contact the bottom convex curved inner wall  15 C nor the upper concave curved inner wall  15 B of the inner sheath  15 . Thus skiving is prevented at the curved portion  24  of the needle and inner and outer sheaths. 
         [0030]    As shown in  FIG. 6 , the needle  16  has penetrated through the septum  17  with the improved needle tip portion  29  but the inner dilator sheath  15  has its leading end  15 A still abutting against the septum  17  prior to dilating at the opening by being pushed therethrough. In this figure one can see first and second echogenic markers  30  and  31  which allow the physician to visualize by ultrasound a location of the tip  29 AB at improved tip portion  29  and also the amount of the needle  16  which has been pushed and penetrated through the septum  17  by use of the marker  31  just beginning to emerge from the hole  17 A in the septum  17 . The first echogenic marker  30  is also shown in  FIG. 5 . These echogenic markers  30  and  31  are also shown in enlarged view in  FIG. 12  along with the improved tip portion  29 . 
         [0031]    In this improvement using the echogenic markers  30  and  31 , visualization of the needle is aided using echo ultrasound. In the prior art the needle and needle tip are very difficult to see under trans-esophageal echo (TEE) or trans thoracic echo (TTE) with only the very tip of the needle being sometimes visible. With the improvement of the present exemplary embodiment with the markers  30  and  31 , visualization is improved since the marker  30  at the tip of the needle can be seen after it crosses through the septum  14 . This prevents advancement of the needle too far which could possibly damage a back wall of the left atrium  11  and inadvertently puncture that wall opposite the septum. Also the markers  30  and  31  provide visualization of how much of the needle has penetrated through the septum. 
         [0032]    The first echogenic marker  30  at the improved tip portion  29  can have a length of approximately 1-2 mm. The second echogenic marker  31  can extend for 1-5 mm, for example, and can be located between 5-30 mm from the needle tip  29 AB as shown in  FIGS. 6 and 12 . As explained above, the second marker  31  can be used for additional visualization during delivery of the needle. Also it is noted these markers  30  and  31  are useful for the user since the echo ultrasound is a 2D medium whereas the device is used in 3D space. This can translate and be used into characterizing the angulation of the improved needle tip portion  29 . 
         [0033]    The visualization for the echogenic markers  30  and  31  is achieved by a surface texturing which can be accomplished in a number of ways including sand or grit blasting, laser ablation of the metal surface, grinding or mechanically modifying the outer surface of the needle. 
         [0034]    With respect to the previously described improved tip portion  29  the transverse end surface  29 A is achieved by cutting or grinding a metal hypo tube of which the needle is constructed (for example stainless steel, cobalt, chrome alloy, nitinol). This angled tip portion is created by grinding, for example, at the distal end. As previously described, the angled tip portion minimizes skiving (cutting off of thin layers of the material from the convex  15 C or concave  15 B curved inside walls of the dilator inner sheath  15  during insertion of the needle). This plastic material, if dislodged, could enter the vascular system and cause a blockage. 
         [0035]    A further improvement will now be described with respect to the improved transseptal needle device  32  shown in  FIG. 7  according to a first embodiment. Here a first embodiment spacer device is shown at  35  and in an end view in  FIG. 8 . This spacer device  35  comprises a springly metal or plastic clip having a split tubular section  36  split at  36 A with clip ears  37 A and  37 B which are pressed together by the user&#39;s fingers to open the springy clip for placement around the hollow needle  16  in the gap G previously described in prior art  FIG. 3 . This insures that the needle tip  29 AB as shown in  FIG. 5  remains just inside the end  15 AA of the inner sheath  15  prior to insertion through the septum. Thereafter when the physician is ready to push the needle tip  29 AB through the septum  17 , the user removes the spacer  35  and the user then closes the gap G by pushing on the needle handle  19  until the arrow portion  21  butts up against the knurled portion  26 A of handle  26  of the inner dilator sheath  15 , at which time a further protrusion of the needle tip through the septum as illustrated in  FIG. 6  is prevented. This improvement can be explained as follows. Traditionally the physician must use X-ray to try and visualize the needle inside the dilator sheath or estimate a distance from a tip of the needle to a tip or end of the conical portion of the inner dilator sheath by looking at the gap G between the needle handle  19  and the inner dilator sheath handle  26  as illustrated in prior art  FIG. 3 . A second embodiment spacer device  38  in an improved transseptal needle device  33 , is shown in  FIGS. 9 and 10 . This spacer device  38  has a handle portion  38 A and a split collar section  38 B received by friction fit in a circular slot  39  in an improvement to the prior art handle  19 . In this embodiment a gap G′ greater than the gap G is provided wherein the physician or user sets the insertion distance of the split collar section  38 B to same gap G described above in connection with prior art  FIG. 3 . Then when the user pushes on the handle  19  the gap G is closed off so that a new gap G′-G results due to the longitudinal extent of the handle portion  38 A. This also achieves safe positioning of the needle tip as previously described. 
         [0036]      FIG. 10  shows an end view looking towards the pointer  21  of the handle  19  and illustrates the collar sloped circular slot  39  for receiving the two split collar sections  38 BA and  38 BB of the split collar  38 B. 
         [0037]      FIG. 11  shows a further improved transseptal crossing device  34  according to a third embodiment for spacing and which is used instead of the spacer devices  35  shown in  FIGS. 7 and 38  in  FIG. 9 . Here first and second visual markers  40  and  41  are provided located in gap G in prior art  FIG. 3 . These visual markers  40  and  41  on the needle  16  are, for example, printed on the needle  16  shaft as shown in  FIG. 11 . The first marker  40  is used relative to the end surface  26 AA of the knurled portion  26 A of the dilator inner sheath handle  26 . This first marker  40  identifies when the tip  29 AB of the needle is approximately 2-3 cm from the opening at the end  15 AA of the inner dilator sheath  15 . The second visual marker  41  indicates when the tip  29 AB is about to exit the distal end of the dilator inner sheath  15  such as shown in  FIG. 5 . These first and second visual markers  40  and  41  external to the body surface  28  allow physicians to accurately position the needle tip  29 AB for delivery without the risk of it being exposed during delivery. 
         [0038]    The first and second markers  40  and  41  can be printed using luminous ink to make them highly visible in dimly lit catheterization labs. These visual markers  40  and  41  are particularly effective for inexperienced users as they become familiar with the procedure and the equipment. 
         [0039]    Although preferred exemplary embodiments are shown and described in detail in the drawings and in the preceding specification, they should be viewed as purely exemplary and not as limiting the invention. It is noted that only preferred exemplary embodiments are shown and described, and all variations and modifications that presently or in the future lie within the protective scope of the invention should be protected.