Abstract:
A device is provided for performing intra myocardial injections. The device comprises a needle, a catheter formed with a lumen, and an abutment member mounted within the lumen for axial movement. The abutment member is movable between a first configuration, wherein it is substantially tube-like and is positioned within the lumen of the catheter, and a second configuration, wherein it extends beyond the distal end of the catheter and is substantially radially flared. Before the needle is advanced to perform an injection, the abutment member is moved to its second configuration to prevent contact between the catheter and the myocardial tissue during the injection.

Description:
FIELD OF THE INVENTION 
   The present invention pertains generally to devices and methods for delivering medicaments to a patient. More specifically, the present invention pertains to devices and methods for performing intra myocardial injections. The present invention is particularly, but not exclusively, useful as a device and method for advancing a needle from a catheter to perform an intra myocardial injection while protecting the myocardial tissue from contact with the catheter. 
   BACKGROUND OF THE INVENTION 
   Intravascular catheters are used in a wide variety of medical procedures by inserting the catheter into the vascular system of the patient at an easily accessible location. Thereafter, the tip of the catheter is advanced through the vasculature to a desired target site. In this manner, virtually any target site in the patient&#39;s vascular system may be remotely accessed. Of particular interest here are those medical procedures that require the use of injection catheters to inject therapeutic or diagnostic agents into various target tissues within the human body. When so used, an advantage of injection catheters is that the target tissue may be accessed by minimally invasive surgical techniques. 
   In many applications the target tissue is within a wall of an organ, such as the heart. For instance, therapeutic or diagnostic agents such as genes, proteins, or drugs may be injected directly into the heart. When the target tissue is within the wall of an organ, however, it is often desirable to inject the therapeutic or diagnostic agent into the tissue proximate the center of the organ wall. In these applications, if the needle of the injection catheter inadvertently passes through the wall, the therapeutic or diagnostic agents that are dispensed from the distal end of the needle will not be effectively delivered to the target tissue. Further, because the injection procedure often requires the thrust of a needle in the distal direction, the required motion can cause the catheter itself to contact and perforate or otherwise injure the wall of the organ. 
   In light of the above, it is an object of the present invention to provide a device and method that protects the myocardial wall from injury and perforation during an intra myocardial injection. Another object of the invention is to provide a device and method for controlling the depth of an intra myocardial injection. Still another object of the invention is to provide a device and method for performing an intra myocardial injection from a catheter in which a removable barrier prevents contact between the catheter and the myocardial tissue and allows the physician to advance the needle with confidence and without fear of perforating the myocardial tissue with the catheter. Yet another object of the present invention is to provide a device and method for performing intra myocardial injections which is easy to implement, simple to perform, and cost effective. 
   SUMMARY OF THE INVENTION 
   In accordance with the present invention, an injector is provided to perform intra myocardial injections while preventing unnecessary trauma to the myocardial tissue. Structurally, the injector includes a catheter having a proximal end and a distal end. Further, the catheter is formed with a lumen that extends from the proximal end to the distal end and defines a longitudinal axis. The injector also includes a needle that is mounted within the lumen of the catheter for axial movement therein. 
   The injector of the present invention also includes an abutment member that has a proximal portion and a distal portion. This abutment member is mounted within the catheter for relative axial movement and is, preferably, made of wire loops formed from a nickel-titanium or other similar alloy. For purposes of the present invention, the distal portion of the abutment member is biased to flare radially outward when not contained inside the catheter. Also, the injector includes a rod having a proximal end and a distal end, with the rod mounted for axial movement within the lumen of the catheter. Importantly, the distal end of the rod is engaged with the proximal portion of the abutment member to move the abutment member within the catheter lumen. 
   For the operation of the present invention, the abutment member is movable by the rod between a first configuration and a second configuration. In its first configuration, the abutment member is substantially tube-like and is positioned within the lumen of the catheter. The rod moves the abutment member axially following the longitudinal axis of the lumen when moving the abutment member into its second configuration. In its second configuration, the distal portion of the abutment member extends axially beyond the distal end of the catheter and is substantially radially flared. 
   In order to perform an intra myocardial injection, the injector is placed at a desired position near or adjacent myocardial tissue. During this placement, the abutment member is in its first configuration. Thereafter, the rod is used to move the abutment member in the distal direction through the distal end of the catheter until the abutment member reaches its second configuration. In its second configuration, the distal portion of the abutment member flares radially and the abutment member is substantially fan shaped. Because the abutment member extends distally from the catheter, the abutment member provides a barrier between the catheter and the myocardial tissue. Therefore, when the needle is advanced and the needle tip penetrates the myocardial tissue to perform the injection, the abutment member prevents contact between the catheter and the myocardial tissue, preventing unwanted advancement of the catheter. As a result, the surgeon may confidently advance the needle without risk of damaging the myocardial tissue with the catheter. 

   
     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 the intra myocardial injector in accordance with the present invention; 
       FIG. 2  is a perspective view of the intra myocardial injector of  FIG. 1  shown with the abutment member in its second configuration in accordance with the present invention; 
       FIG. 3A  is a cross sectional view of the injector of  FIG. 2  shown with the abutment member in its first configuration in accordance with the present invention; 
       FIG. 3B  is a cross sectional view of the injector of  FIG. 2  shown with the abutment member in its second configuration in accordance with the present invention; and 
       FIG. 3C  is a cross sectional view of the injector of  FIG. 2  shown with the abutment member in its second configuration and with the needle advanced and penetrating myocardial tissue in accordance with the present invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring initially to  FIG. 1 , an intra myocardial injector in accordance with the present invention is shown, and is generally designated  10 . As shown in  FIG. 1 , the injector  10  includes a catheter  12  that extends along an axis  14  from a proximal end  15  to a distal end  16 . As is shown, the proximal end  15  of the catheter  12  is connected to tubing  13 . For purposes of the present invention, the tubing  13  is in fluid communication with a vessel  17  for holding medicament or other fluid for medical treatment. As is further shown, the tubing  13  also includes a port  19  that provides access for manipulation of internal components of the catheter  12 . 
   Referring now to  FIG. 2 , the injector  10  is shown to include a needle  18  that terminates at a needle tip  20 . As shown in  FIG. 2 , the needle  18  has been advanced so that the needle tip  20  extends beyond the distal end  16  of the catheter  12 . Further, the injector  10  is shown to include an abutment member  22 . As shown, the abutment member  22  is formed from a plurality of loops  24  of wire  26 . Specifically, the abutment member  22  is formed with overlapping loops  24  that are biased to radially extend from the axis  14 . Further, the abutment member  22  may include a webbing  25  that interconnects adjacent loops  24 . Such a webbing  25  can comprise a high-friction material. For the present invention, the abutment member  22  may include engagement elements  28  such as tines that extend from exemplary loops  24   a ,  24   b , or a high friction surface. 
   Turning now to  FIG. 3A , the internal features of the injector  10  may be understood. As shown in  FIG. 3A , the catheter  12  forms a lumen  30  that extends along the axis  14  to the distal end  16 . Unlike in  FIG. 2 , the abutment member  22 ′ is positioned completely within the lumen  30 , i.e., in its first configuration. As shown, when in its first configuration, the abutment member  22 ′ is substantially tube-like. Specifically, the abutment member  22 ′ includes a proximal portion  32  and a distal portion  34  that are substantially cylindrical. 
   In  FIG. 3A , it is further shown that the injector  10  includes a pusher rod  36  that includes a distal end  38 . As shown, the pusher rod  36  is received within the lumen  30  and is axially movable with respect to the catheter  12 . For purposes of the present invention, the distal end  38  of the pusher rod  36  engages the proximal portion  32  of the abutment member  22 ′ to cause movement of the abutment member  22 ′. In certain embodiments, the rod  36  and the abutment member  22  may be a single piece. 
   Still referring to  FIG. 3A , the needle  18  is shown positioned entirely within the lumen  30 , with the end  16  of the catheter  12  distal of the needle tip  20 . Structurally, the needle  18  may be mounted to a needle hub (not shown) for movement with respect to the lumen  30  of the catheter  12 . 
   Referring now to  FIG. 3B , the abutment member  22 ″ is shown in its second configuration. Specifically, as shown, the distal portion  34  of the abutment member  22 ″ is shown extended from the distal end  16  of the catheter  12 . Because it is radially biased, the distal portion  34  of the abutment member  22 ″ flares radially when extended beyond the distal end  16  of the catheter  12  and takes a fan shape. Stated differently, the distal portion of the abutment member  22  is flared radially outward to establish an annular-shaped barrier at the distal extreme of the abutment member  22 . As shown in  FIG. 3B , the needle  18  is still retracted within the catheter  12 . 
   Referring now to  FIG. 3C , it can be seen that the needle  18  has been advanced to extend the needle tip  20  beyond the distal end  16  of the catheter  12  and the abutment member  22 ″. Preferably, the needle tip  20  extends between 3 and 7 millimeters beyond the distal portion  34  of the abutment member  22 ″. 
   Referring now to  FIGS. 3A-3C  collectively, the operation of the present invention may be understood. Initially, the injector  10  is configured as in  FIG. 3A  with the abutment member  22 ′ in its first configuration. When an intra myocardial injection is desired, the injector  10  is placed adjacent myocardial tissue  42 . Next, as shown in  FIG. 3B , the pusher rod  36  is advanced and the distal end  38  of the rod  36  forces the abutment member  22  in the distal direction. The abutment member  22  is moved distally until it reaches its second configuration. In the second configuration, the distal portion  34  of the abutment member  22 ″ flares radially and provides a barrier between the distal end  16  of the catheter  12  and the myocardial tissue  42 . When the injector  10  is moved toward the myocardial tissue  42 , the abutment member  22  abuts the tissue  42  and prevents further movement of the catheter  12  in the distal direction. In further detail,  FIGS. 3A and 3B  show the proximal portion of the abutment member  32  inside the lumen  30  of the catheter  12  when the distal portion of the abutment member  34  is in its first configuration. As shown in  FIG. 3C , the proximal portion of the abutment member  32  remains inside the lumen  30  of the catheter  12  when the distal portion of the abutment member  34  is in its second configuration. Further, the engagement elements  28  (shown in  FIG. 2 ) on the abutment member  22  may pierce or contact and engage the myocardial tissue  42  to anchor the injector  10  in position. 
   With the abutment member  22 ″ in its second configuration, the needle  18  may be linearly advanced to extend the needle tip  20  as shown in  FIG. 3C . A linear advancement of the needle  18  may be accomplished by pushing the needle hub (not shown) relative to the catheter  12 , or otherwise pushing the needle  18  relative to the catheter  12  as known in the art. As a result of its advancement, the needle tip  20  extends beyond the distal end  16  of the catheter  12  and beyond the distal portion  34  of the abutment member  22 ″ to penetrate the myocardial tissue  42  to an approximate depth of between 3 and 7 millimeters. When the myocardial tissue  42  has been penetrated by the needle tip  20  at the appropriate depth, a medicament or other treatment fluid may be injected through the needle tip  20  as is well known in the art. 
   After the injection has been performed, the needle  18  is retracted within the lumen  30 , as illustrated in  FIG. 3B . Then the abutment member  22 ″ is withdrawn into the lumen  30  by the pusher rod  36 , as illustrated in  FIG. 3A . Thereafter, the injector  10  is removed from the patient&#39;s vasculature. 
   While the particular Myocardial Injector 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.