Abstract:
A catheter system includes a positioning catheter for receiving an injection needle into its lumen. Structurally, the injection needle incorporates a plurality of loops that are mounted directly onto its shaft. As the injection needle is moved in a distal direction to exit from the lumen of the catheter, the loops are individually biased to transition from a folded configuration, and into a deployed configuration. In their deployed configurations, the loops create a barrier that is oriented perpendicular to the needle. Thus, the barrier acts to limit the depth of insertion of the needle into target tissue of a patient, to a predetermined depth, and to prevent perforation of the target tissue by the catheter tip.

Description:
This application is a continuation-in-part of application Ser. No. 14/079,841, filed Nov. 14, 2013, which is now abandoned, and which is a divisional of application Ser. No. 12/977,737, filed Dec. 23, 2010, which is now abandoned. The contents of application Ser. Nos. 14/079,841 and 12/977,737 are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention pertains generally to injection catheters. More particularly, the present invention pertains to systems and methods for injecting fluid medicaments into myocardial tissue, and other internal tissue of a patient. The present invention is particularly, but not exclusively, useful as a system and method having a catheter-based injection needle that incorporates mechanical means to limit needle insertion into tissue to within a predetermined depth and to prevent perforation of the catheter tip through the wall of the tissue. 
     BACKGROUND OF THE INVENTION 
     Injecting fluid medicaments into internal tissues of the body (e.g. the myocardium) can be problematic. This is particularly so due to the fact there is no way for the surgeon to have a direct visualization of the injection site. Although indirect visualization techniques, such as fluoroscopy, can significantly aid in advancing an injection needle to the intended injection site, additional control at the site may be required in order to properly insert a needle into tissue for a precise injection. For instance, control over the depth to which an injection needle is inserted into the tissue may be a crucial consideration. Further, and specific to the heart, perforation of the catheter tip through the heart wall causes blood to leak into the pericardial sack, which can be fatal. 
     As a practical matter, a reliance on extracorporeal control over an injection needle, for the specific purpose of precisely attaining a desired depth of needle insertion into tissue, is complicated by several factors. Not the least of these involves the proper positioning of the injection needle at the target tissue site, before needle insertion. Typically, such a pre-positioning of an injection needle can be successfully accomplished using a positioning catheter that incorporates radiopaque markers (e.g. fluoroscopy). Nevertheless, this pre-positioning relies on only indirect visual indicators that may fail to provide sufficient control for inserting the needle into target tissue. 
     In light of the above, it is an object of the present invention to provide a system and method for performing an injection of fluid medicament into a target tissue of a patient that provides for tactile indications of a proper needle insertion. Another object of the present invention is to ensure that such a needle insertion is performed to within a precise depth into the target tissue and to prevent perforation of the tissue by the catheter tip. Still another object of the present invention is to provide a system and method for performing an injection of fluid medicament into a target tissue that is relatively simple to manufacture, is easy to use, and is comparatively cost effective. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, a catheter-based injection needle is provided that controls the depth to which the needle can be inserted in an internal target tissue of a patient (e.g. the myocardium). For the purpose of controlling the insertion depth of the needle, a web member (barrier) is mounted onto the shaft of the needle at a distance “d”, proximal to the distal end of the needle. During a procedure (i.e. an injection of a fluid medicament), this web member is caused (biased) to flare outwardly from the needle. With the web member in this flared configuration, an advancement (insertion) of the needle into the target tissue is limited. Specifically, insertion of the needle is limited to the distance “d”. More specifically, this happens when the barrier makes contact with a surface of the target tissue. As envisioned for the present invention, the distance “d” can be varied according to the particular procedure being employed and the desires of the user. 
     Structurally, a system in accordance with the present invention includes a hollow positioning catheter having a lumen that extends between a proximal end and a distal end of the catheter. Also included in the system is the injection needle mentioned above. For purposes of the present invention, the injection needle is dimensioned to be received into the lumen of the positioning catheter for back-and-forth (proximal-and-distal) movements in the lumen. Further, the web member is dimensioned to pass through the lumen of the catheter along with the injection needle. To do this, the web member is confined by the positioning catheter to assume a folded configuration inside the lumen of the positioning catheter. While the web member is held by the positioning catheter in its folded configuration, the web member is substantially cylindrical shaped and is oriented parallel to the co-axis of the needle and the catheter. With the web member in this folded configuration, and with the positioning catheter pre-positioned in the vasculature of a patient, the injection needle can be advanced through the positioning catheter to the site of the target tissue. Alternatively, if the positioning catheter is not pre-positioned in the vasculature of the patient, the injection catheter can be advanced into the vasculature together with the positioning catheter. In either case, once the system is adjacent the target tissue site, the injection needle and web member are deployed from the distal end of the positioning catheter. 
     When the injection needle is deployed from the distal end of the positioning catheter, the web member is no longer constrained by the catheter, and it is biased into its flared configuration. As envisioned for the present invention, a deployment of the injection needle (web member) can be accomplished either by withdrawing the catheter in a proximal direction relative to the injection needle, or by advancing the injection needle in a distal direction relative to the catheter. Regardless how it is deployed, when it is in its flared configuration, the web member establishes a disk-shaped barrier that is oriented substantially perpendicular to the co-axis of the catheter and the needle. As indicated above, this barrier is located at the selected distance “d” from the distal end of the injection needle. As also indicated above, the purpose here is to limit the insertion depth of the injection needle to the distance “d”. Also, when deployed, the barrier acts to prevent any distal movement of the catheter beyond the barrier, to thereby prevent the catheter tip from perforating the target tissue. Once an injection has been completed, the injection needle can be withdrawn into the lumen of the catheter. Inside the lumen, the web member will again assume its folded configuration. The system can then be removed from the patient. 
     Several different structural arrangements for the barrier that is established by the web member in its flared configuration are envisioned for the present invention. These include an arrangement wherein the web member comprises a plurality of elongated extensions, with each extension having a first end mounted on the injection needle. For this arrangement, each extension is biased to move the opposite (second) end radially outward from the axis with a deflection of the extension. Another possible arrangement for the web member includes a plurality of interconnected straight wires. In this arrangement, a first plurality of base wires will each have an end attached to the needle. A second plurality of wires will then have each of their ends attached to a respective base wire to thereby interconnect the base wires. Also, in another arrangement, the web member may comprise a plurality of elongated wire loops. Further, for each of the web member arrangements, the barrier will have a diameter “D” in its flared configuration and, typically, “D”/2 will be less than “d”. As mentioned above, however, for some procedures it may be desirable for “d” to be less than “D”/2. In other aspects of the invention, the barrier can be radiopaque and made of a material such as cobalt chromium, platinum, nitinol or stainless steel. Also, the injection needle will preferably be less than or equal to 18 gauge, and the variously selected distance “d” will generally be less than 15 mm. 
     In another embodiment of the present invention a catheter system for performing an injection of fluid medicament into a tissue of a patient is provided which creates a web member with a penetration depth barrier for an injection needle. Specifically, for this embodiment, the web member comprises a plurality of loops. Like other embodiments of the present invention, this embodiment includes a positioning catheter having a proximal end and a distal end which has a lumen extending between the ends. Also included is an injection needle that is positioned in the lumen of the catheter for reciprocating movement through the lumen. Structurally, the injection needle has a proximal end and a distal end, and it defines a longitudinal axis. 
     For this embodiment of the present invention, each loop in the barrier of the web member is essentially an elongated wire having a first end and a second end which are bent around a midpoint of the wire to define a loop plane. In combination with the injection needle, the two ends of each loop are affixed to the needle at respective points in a plane that is perpendicular to the axis of the needle. Further, each loop is affixed to the needle to avoid any overlap or interference with another loop during an operation of the catheter system. 
     An important function for this embodiment of the present invention is that each loop of the web member is biased to transition in the loop plane between a folded configuration and a deployed configuration. In detail, for its folded configuration each loop has a first portion that extends between the first end of the loop and the midpoint. It also has a second portion that extends between the second end of the loop and the midpoint. In the folded configuration, the first portion is aligned substantially parallel to the second portion. For the deployed configuration of the web member, however, the first portion and the second portion of each loop are bowed away from each other to form an oval-shaped loop. To perform a transition between these configurations, the injection needle is moved axially relative to the catheter. 
     In its folded configuration each loop of the web member is constrained inside the lumen of the catheter. When the web member has been advanced in a distal direction beyond the distal end of the catheter, however, the web member is no longer constrained by the catheter and each loop transitions into its deployed configuration. It is also to be noted that during the configuration transition of a loop, its loop plane is rotated through a deployment angle β about an axis perpendicular to the axis of the needle. The consequence here is that during their configuration transition the loops (i.e. web member) are deployed to create a barrier which is established with the midpoints of each loop located at a distance “d” proximal the distal end of the injection needle. With this deployment, the system of the present invention prevents an insertion of the needle any deeper than the distance “d” into the tissue of the patient. 
     As envisioned for the present invention, when the injection needle is withdrawn inside the lumen of the catheter, and each loop in the web member is constrained by the catheter into its folded configuration, β will equal 0°. On the other hand, when the web member has been advanced beyond the distal end of the catheter, each loop is biased through the configuration transition from its folded configuration and into its deployed configuration to create the barrier. In this deployed configuration, the deployment angle β will typically be in a range between 60° and 90°. 
     In addition to the above disclosure for a web member that is created by a plurality of loops, it is also envisioned that in a preferred embodiment, the loops of the web member will be radiopaque and made of a material such as cobalt chromium, platinum, nitinol or stainless steel. Further, the injection needle will preferably be less than or equal to 27 gauge, and the distance “d” established for the barrier of the web member will be less than about 15 mm. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The novel features of this invention, as well as the invention itself, both as to its structure and its operation, will be best understood from the accompanying drawings, taken in conjunction with the accompanying description, in which similar reference characters refer to similar parts, and in which: 
         FIG. 1  is a perspective view of a system of the present invention shown in an intended operational environment; 
         FIG. 2  is a perspective view of the system with the injection needle deployed from the distal end of a positioning catheter, and with the web member biased into its flared configuration; 
         FIG. 3  is a perspective view of the system with the injection needle withdrawn into the lumen of the positioning catheter, and with the web member constrained by the positioning catheter into its folded configuration; 
         FIG. 4  is a front elevation view of an alternate embodiment of the web member; 
         FIG. 5  is a front elevation view of another alternate embodiment of the web member; 
         FIG. 6A  is a perspective view of a preferred embodiment of the present invention, with a plurality of loops constrained inside a catheter in a respective folded configuration, with portions of the catheter broken away for clarity; 
         FIG. 6B  is a view of the present invention as shown in  FIG. 6A  with the plurality of loops advanced distally beyond the distal end of the catheter with the loops biased into their respective deployed configuration; and 
         FIG. 7  is a cross-section view of the catheter system as seen along the line  7 - 7  in  FIG. 6A . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring initially to  FIG. 1 , a system in accordance with the present invention is shown in its intended operational environment and is generally designated  10 . As shown, the system  10  includes a catheter  12  that can be advanced into the vasculature of a patient  14 . Also, the system  10  includes a source  16  of a fluid medicament that is to be injected into an internal tissue of the patient  14  (e.g. the myocardium). For the system  10 , the catheter  12  is preferably a positioning type catheter  12  having a distal end  18  and a proximal end  20 , with a lumen  22  that extends along the length of the catheter  12  between the ends  18 / 20 . As indicated in  FIG. 2 , the catheter  12  defines a longitudinal axis  24 . 
       FIG. 2  shows an injection assembly for the present invention that is generally designated  26 . More specifically, the injection assembly  26  includes an injection needle  28  that has a distal end  30 . Preferably, the injection needle  28  is less than or equal to 27 gauge. Additionally, the injection assembly  26  includes a web member  32  that is fixedly mounted on the injection needle  28  at a distance “d” proximal to the distal end  30  of the injection needle  28 . Typically, the distance “d” will be less than ten millimeters. In other embodiments, however, the distance “d” can be adjustable. Stated differently, the exact length for distance “d” can be varied as required for the particular procedure (e.g. 3-7 mm). 
     For the preferred embodiment of the web member  32  shown in  FIG. 2 , the web member  32  includes a plurality of elongated extensions  34 , of which the extension  34   a ,  34   b  and  34   c  are exemplary. In detail, an end of each extension  34  is affixed to the injection needle  28  at a location  36  (i.e. at the distance “d” from distal end  30 ). As intended for the system  10 , all of the extensions  34  of web member  32  are biased to assume the position shown in  FIG. 2 . Specifically, each of the extensions  34  is biased to become oriented substantially perpendicular to the axis  24  when it is unrestrained. Consequently, under these unrestrained conditions, the web member  32  assumes a flared configuration that is generally disk-shaped, as shown in  FIG. 2 . In addition to its flared configuration, however, the web member  32  can be mechanically restrained to assume a folded configuration (see  FIG. 3 ). 
     As shown in  FIG. 3 , when the injection assembly  26  is positioned inside the lumen  22  of catheter  12 , all of the extensions  34  are forced to become individually aligned, and oriented substantially parallel to the axis  24 . Under these conditions, the web member  32  becomes cylindrical shaped, to assume a folded configuration. For purposes of the present invention, it is important that the injection assembly  26  be moveable back-and-forth (i.e. proximal-and-distal) through the lumen  22  of the catheter  12 , when the web member  32  is in its folded configuration. 
     As envisioned for the present invention, the web member  32  can be selectively transitioned between its flared configuration ( FIG. 2 ) and its folded configuration ( FIG. 3 ). For the system  10 , this transition can be accomplished in either of two ways. For one, starting with the web member  32  in the folded configuration ( FIG. 3 ), the catheter  12  can be withdrawn in a proximal direction (arrow  38 ) relative to the injection assembly  26 . The consequence here is that when the distal end  30  of the injection needle  28  is more than the distance “d” from the distal end  18  of the catheter  12 , the web member  32  is biased into its flared configuration ( FIG. 2 ). For another, again starting with the web member  32  in its folded configuration, the injection assembly  26  can be advanced in a distal direction (arrow  40 ) relative to the catheter  12 . Likewise, when the distal end  30  of the injection needle  28  is more than the distance “d” from the distal end  18  of the catheter  12 , the consequence is that the web member  32  will assume its flared configuration. To return the web member  32  from its flared configuration to its folded configuration, these operations simply need to be reversed in order to retract the injection assembly  26  into the lumen  22  of the catheter  12 . 
     Two different alternate embodiments of the web member  32 , each of which is envisioned for use with the system  10 , are respectively shown in  FIG. 4  and  FIG. 5 . In  FIG. 4  an alternate embodiment of a web member  32 ′ is shown to include a plurality of base wires  42 , and a plurality of interconnect wires  44 . More specifically, for the web member  32 ′, each base wire  42  will have an end that is connected directly onto the injection needle  28 . The interconnect wire  44 , on the other hand, will have its opposite ends connected to adjacent base wires  42  (e.g. base wires  42   a  and  42   b ). In  FIG. 5 , the web member  32 ″ is shown to include a plurality of loops  46 . For this embodiment, each loop  46  is connected to the injection needle  28 . As shown in  FIG. 4  and  FIG. 5 , the respective web members  32 ′ and  32 ″ are shown in their respective flared configurations. In this configuration, all embodiments (i.e. web member  32 , web member  32 ′ and web member  32 ″) will establish a diameter “D” for its disk-shape. In most instances, “D”/2 will be less than “d”, but it may happen that it is desirable for “d” to be less than “D”/2. Preferably, the barrier that is created by the web member  32 ,  32 ′ or  32 ″ is radiopaque and is made of cobalt chromium, platinum, nitinol or stainless steel. 
     In an operation of the system  10 , the positioning catheter  12  can be pre-positioned in the vasculature of patient  14 , or the injection assembly  26  can be inserted into the lumen  22  of the catheter  12  and this combination can be advanced into the vasculature. In either case, once the distal end  18  of the positioning catheter  12  is positioned at an injection site, adjacent to the target tissue (not shown), the injection assembly  26  is deployed from the catheter  12  (i.e. there is a transition of the injection assembly  26  as shown in  FIG. 3  to how it is shown in  FIG. 2 ). With this deployment, the web member  32  becomes unrestrained and is biased into its flared configuration (see  FIG. 2 ). Thus, this flared configuration effectively establishes a barrier at the distance “d” from the distal end  30  of the injection needle  28 . 
     With the injection assembly  26  configured as shown in  FIG. 2 , the injection needle  28  is inserted into the target tissue. As indicated above, the target tissue is envisioned as being either internal tissue, such as the myocardium, or external tissue like skin. Importantly, however, in each instance, the depth of this insertion into the target tissue is limited to the distance “d” by the barrier that is created when the web member  32  is biased into its flared configuration. Fluid medicament from the source  16  can then be injected into the patient  14 . 
     Once the injection of fluid medicament has been completed, the injection needle  28  is withdrawn from the target tissue. The injection assembly  26  can then be retracted into the lumen  22  of catheter  12  until the barrier is collapsed when the web member  32  is returned to its folded configuration. The system  10  can then be removed from the patient  14 . 
     In  FIGS. 6A, 6B and 7 , another embodiment of the present invention is shown. As clearly shown in  FIGS. 6A and 6B , this embodiment includes a web member  33  (see  FIG. 6B ) which comprises a plurality of independent loops  48 . In  FIGS. 6A and 6B , the independent loops  48   a ,  48   b  and  48   c  are shown as examples of the plurality of such loops  48  that may be used. 
     A comparison of  FIG. 6A  with  6 B shows that the web member  33  can have two different configurations. For its folded configuration, as shown in  FIG. 6A , the independent loops  48   a ,  48   b  and  48   c  of the web member  33  are constrained by the guiding (positioning) catheter  12  inside the lumen  22  of the catheter  12 . On the other hand, for its deployed configuration, as shown in  FIG. 6B , the independent loops  48   a ,  48   b  and  48   c  of the web member  33  are not constrained by the guiding (positioning) catheter  12  inside the lumen  22  of the catheter  12 . Instead, for the deployed configuration, the web member  33  that is affixed to the injection needle  28  has been advanced beyond the distal end  18  of the catheter  12  to a point where the independent loops  48   a ,  48   b  and  48   c  are biased into the deployed configuration. 
     The structural details of each independent loop  48  will, perhaps, be best appreciated with specific reference to the independent loop  48   a  in  FIG. 6B . There it will be seen that the independent loop  48   a  is essentially an elongated wire having a first end  50  and a second end  52 . As shown, this wire is bent around a midpoint  54  and the ends  50  and  52  of the wire are affixed to the injection needle  28  by any suitable means well known in the art, such as by welding. The consequence of this combination of structure is that the ends  50  and  52 , together with the midpoint  54  of the independent loop  48  define a loop plane. Further, as indicated in  FIG. 6B , during a configuration transition between a folded configuration of the web member  33  ( FIG. 6A ) and a deployed configuration ( FIG. 6B ), the loop plane defined by each respective independent loop  48  will rotate through a deployment angle β. As also shown in  FIG. 6B , the independent loop  48   a , which is exemplary of all such loops  48 , defines a first portion  56  that extends between the first end  50  and the midpoint  54   a  of the loop  48   a . Likewise, a second portion  58  extends between the second end  52  and the midpoint  54   a  of the loop  48   a.    
     For a detailed disclosure of a configuration transition of the web member  33  between its folded and deployed configurations, reference is variously made to  FIG. 6A, 6B or 7 . In this cross reference it is to be appreciated that, although the disclosure here is primarily directed to a transition from the folded configuration ( FIG. 6A ) to the deployed configuration ( FIG. 6B ), the present invention also envisions transitions from the deployed configuration ( FIG. 6B ) to the folded configuration ( FIG. 6A ). 
     With the above in mind,  FIG. 6A  shows each of the independent loops  48   a, b  and  c  individually constrained within the lumen  22  of the guiding catheter  12 . In this configuration, each loop  48  is stressed with their respective first portion  56  substantially parallel with the second portion  58  (cross reference  FIG. 6A  with  FIG. 7 ). It should also be noted that when a loop  48  is constrained into its folded configuration, the deployment angle of its loop plane will be essentially zero (i.e. β=0°). On the other hand, when the web member  33  is deployed, its independent loops  48   a, b  and  c  are biased into an unstressed state (i.e. they are unconstrained by the catheter  12 ) and each loop  48  will assume an elliptically shaped configuration. Stated differently, in a deployed configuration (i.e. unconstrained) the first portion  56  and the second portion  58  are bowed away from each other. Furthermore, as indicated in  FIG. 6B , the respective loop plane of each independent loop  48  is rotated with respect to the axis  24  through the deployment angle β. Typically, for a deployed configuration of the web member  33 , the deployment angle β will be in a range between 60° and 90° (i.e. 60°&lt;β&lt;90°). 
     An important feature of the present invention is that, in combination, each loop  48  is affixed to the injection needle  28  to avoid overlap and interference with another loop  48  during a configuration transition. In the event, the consequence here is that with a deployment of the web member  33 , each independent loop  48   a - c  will extend to become located at an axial distance “d” from the distal end  30  of the injection needle  28 . The result here is to establish a barrier that will prevent the insertion of the injection needle  28  into tissue through a distance greater than “d”. 
     While the particular Injection Needle Insertion Barrier as herein shown and disclosed in detail is fully capable of obtaining the objects and providing the advantages herein before stated, it is to be understood that it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as described in the appended claims.