Abstract:
A catheter introducer and a method of introducing a catheter into a heart. The catheter introducer includes a front puncturing end and a main body portion which defines an upwardly-opening trough therein. A catheter is placed in piggy-back fashion within the trough, and the puncturing end of the tool is inserted into the heart, so that the catheter is delivered into the heart essentially simultaneously with the piercing of the heart wall. The catheter introducer results in a faster introduction of the catheter, and minimizes blood loss and trauma to the heart.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention relates to a catheter introducer and a method of implanting a catheter within an area of the heart, such as the left ventricle.  
       BACKGROUND OF THE INVENTION  
       [0002]     Mammals, including humans, have a double-circuit heart that functions similar to two separate, side-by-side pumps, each with two chambers. On the right side of the heart, blood travels from the right atrium to the right ventricle, and the right ventricle pumps the blood through the pulmonary artery to the lungs for oxygenation. When the oxygenated blood returns to the heart, the blood enters the left atrium before traveling to the left ventricle where the blood is pumped out again with greater force. The left ventricle forces the blood through the ascending aorta and out to the body. The left ventricle of the heart, whether a human heart or an animal heart, thus can be used as a measuring site for monitoring various heart functions, such as left ventricular pressure. This monitoring can be carried out through the use of a catheter which is implanted within the left ventricle, and then appropriately connected to a sensor which senses the pressure in the catheter and transmits pressure readings. A catheter implanted within the left ventricle can also be used for purposes other than monitoring heart function. For example, the implanted catheter can be used to administer drugs directly into the left ventricle, can be used as a vascular access port, can be used for blood collection, or can be used as a port for introduction of a device into the heart, such as, for example, a fiber-optic camera or pressure sensitive crystal. In some cases, the catheter is left in the patient so that heart function can be monitored on a regular basis, or for drug dosing at regular intervals.  
         [0003]     The conventional method for introducing a catheter directly through the muscle wall of the heart of an animal, such as a canine, is achieved through the use of suitable scissors, such as iris scissors, or a scalpel blade which incises through the heart wall at the thinnest portion of the heart wall in the left ventricle, known as the “dimple”. Forceps, such as mosquito hemostatic forceps, are then used to hold the stab incision in the left ventricular wall open to allow introduction of the catheter into the heart. This method thus necessarily involves several steps, which complicates and lengthens the time required for the procedure. Further, because a large hole or slit is initially created in the heart muscle, this conventional method can result in significant blood loss and trauma to the heart.  
         [0004]     The present invention is directed to a catheter introducer and a method of introducing a catheter directly into the heart, which overcomes the disadvantages of the conventional method described above. More specifically, the catheter introducer according to the invention is an elongated tool having a puncturing or piercing end and a trough-shaped main body portion. The main body portion defines a sidewardly-opening elongated channel or trough therein. A conventional catheter is placed in piggy-back fashion within the trough, and the puncturing end of the tool is inserted into the heart until the tool has penetrated the heart sufficiently to deliver the tip of the catheter into a targeted area of the heart, such as the left ventricle. While the catheter is held in place, the introducer or tool is then withdrawn from the heart, leaving the catheter in place. Sutures are utilized to secure the catheter in position.  
         [0005]     The catheter introducer pursuant to the invention allows the catheter to be implanted within the heart wall substantially simultaneously while the opening in the heart wall is being made by the puncturing end of the tool, thereby reducing the amount of time for the procedure. Further, the introducer tool and the catheter carried thereon together define a solid, rod-like configuration which effectively plugs the opening made by the puncturing end of the introducer during the procedure so as to minimize blood loss and cause far less trauma to the heart. Trauma is minimized because the concentric rings of muscle fibers are stretched as they are displaced by the smooth sides of the tool rather than cut or torn.  
         [0006]     Other objects and purposes of the invention will be apparent to persons familiar with apparatus of this type upon reading the following description and inspecting the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]      FIG. 1  is an elevational and fragmentary side view of the catheter introducer according to the invention.  
         [0008]      FIG. 2  is a plan view of the catheter introducer.  
         [0009]      FIG. 3  is a longitudinal cross-sectional view of the catheter introducer taken generally along line  3 - 3  in  FIG. 2 .  
         [0010]      FIG. 3A  is an enlarged, transverse cross-sectional view of the catheter introducer taken generally along line  3 A- 3 A of  FIG. 3 .  
         [0011]      FIG. 4  is a perspective view of a canine heart primarily showing the left ventricle.  
         [0012]      FIG. 5  is an enlarged, fragmentary view of the apex of the left ventricle shown in  FIG. 4 .  
         [0013]      FIG. 6  is an enlarged, fragmentary cross-sectional view of the apex of the left ventricle of  FIG. 4 , with the catheter introducer inserted into the muscle wall of the left ventricle.  
         [0014]      FIG. 7  is an enlarged, fragmentary view similar to  FIG. 5 , with the catheter in place in the left ventricle. 
     
    
       [0015]     Certain terminology will be used in the following description for convenience in reference only, and will not be limiting. For example, the words “upwardly”, “downwardly”, “rightwardly” and “leftwardly” will refer to directions in the drawings to which reference is made. The words “inwardly” and “outwardly” will refer to directions towards and away from, respectively, the geometric center of the device and designated parts thereof. This terminology will include the words specifically mentioned, derivatives thereof, and words of similar import.  
       DETAILED DESCRIPTION  
       [0016]     Referring to  FIGS. 1-3A , there is illustrated a catheter introducer or tool  10  according to the invention. The catheter introducer generally includes a front puncturing end  11 , a rear manipulating end  12 , and a main or central body portion  13  disposed between and connected to front and rear ends  11  and  12 .  
         [0017]     Puncturing end  11  of introducer  10  is defined by a solid and generally bullet-shaped nose  15  which defines a pointed tip  16  at a front end thereof. The outer surface of nose  15  is smooth along its circumference and tapers gradually outwardly as same projects rearwardly from tip  16  towards end  12 .  
         [0018]     The main body portion  13  projects rearwardly from puncturing end  11  and is defined by a generally arcuate wall  20  ( FIG. 3A ). Wall  20  includes a pair of side walls  21  which respectively terminate in upper flat edges  23  which extend along a substantial extent of the longitudinal length of introducer  10 , and a lower wall  24  which smoothly adjoins the respective side walls  21 . A generally upright rear wall  25  which forms part of rear end  12  extends transversely between and is joined to rear edges of the respective side walls  21  and a rear edge of lower wall  24 . Rear wall  25  defines an upper surface  26  which adjoins to and is flush with surfaces  21 . Arcuate wall  20  defines upper and lower oppositely facing surfaces  30  and  31 .  
         [0019]     The central body portion  13 , through the shape of its arcuate wall  20 , defines an upwardly-opening, elongate and arcuate trough or channel  32 . In the illustrated embodiment, trough  32  extends along a substantial portion of the longitudinal length of the introducer  10 , starting at a point which is located rearwardly from tip  16  and terminating at rear wall  25 . Trough  32  has a terminal front end  36  which in the illustrated embodiment has the shape of a partial ellipse when viewed from above.  
         [0020]     Trough  32  has a bottom surface  40  which is defined by upper surface  30  of arcuate wall  20 . As bottom surface  40  of trough  32  projects forwardly toward puncturing end  11 , bottom surface  40  (when viewed in cross-section as in  FIG. 3 ) curves smoothly upwardly to a point which is at the same height as a rear upper surface  41  of nose  15 . This configuration of bottom surface  40  provides front end  36  of trough  32  with a surface  42  which curves forwardly as same projects upwardly.  
         [0021]     The rear end  12  of introducer  10  mounts thereon a pair of sidewardly projecting and generally horizontally-oriented wings  50  or handles which assist in manual manipulation of introducer  10 . In the illustrated embodiment, wings  50  are oriented at the same vertical height as one another on rear end  12 , and have a generally semicircular outer edge as shown in  FIG. 2 . It will be appreciated that other configurations of wings  50  are within the scope of the invention, and that the curved shape shown herein is presented only as an example of one possible configuration of wings  50 .  
         [0022]     As shown in  FIG. 1 , the trough  32  is configured to receive a conventional catheter  51 . In this regard, trough  32  preferably has a depth which allows approximately three-quarters of the diameter of the catheter  51  to be submerged in trough  32  when positioned on bottom surface  40 .  
         [0023]      FIG. 4  depicts a heart  53  of an animal, and in the illustrated embodiment, heart  53  is a canine heart. The heart  53  in  FIG. 4  is positioned so as to primarily show the left ventricle  54 . The left ventricle  54  defines an apex  55  at a lower portion thereof, and a dimple  56  which represents an area of the apex  55  where concentric muscles (schematically represented by concentric lines in  FIGS. 4 and 5 ) of the heart  53  join to one another.  
         [0024]     The catheter  51  is introduced or implanted within the heart  53  utilizing introducer or tool  10  according to the invention as follows. Entry into the canine is made by one of two conventional approaches, either a thoracic approach or an abdominal approach in order to expose the apex of the heart  53 . The pericardium is incised to free up the apex  55  of the heart  53 . A circular purse string-style suture  60  is placed around the dimple  56 , which dimple  56  defines the targeted penetration area of the left ventricle  54 . Stay sutures  61  are placed on opposite sides of the dimple  56  to assist in holding the heart  53  in the proper position within the chest cavity of the canine.  
         [0025]     Next, the tool  10  is positioned so that trough  32  opens generally upwardly, and the catheter  51  is positioned inside the trough  32  so that a frontmost end  52  thereof is located slightly rearwardly from the curved surface  42 , with the catheter  51  resting on the bottom surface  40  of trough  32 . The front puncturing end  11  of introducer  10  is positioned at the dimple  56 , and, using the stay sutures  61  to hold the heart in position, the introducer  10  is pushed into the wall  65  of the left ventricle  54  to pierce same and make an opening. The introducer  10  is pushed into the left ventricle wall  65  until the catheter  51  has penetrated the heart wall  65  and projects into the left ventricle  54  as shown in  FIG. 6 . The catheter  51  is then held in place with the fingers or with forceps, and the introducer  10  is withdrawn from the heart wall  65 , leaving the catheter  51  in place in the heart  53 .  
         [0026]     It will be appreciated that the curved surface  42  of trough  32  acts as a ramp, whereby as the introducer  10  is retracted and moved rearwardly away from the catheter  51  and the heart  53 , the frontmost end  52  of catheter  51  slides upwardly along surface  42  to assist in removal of introducer  10  from the heart  53 . After withdrawal of the introducer  10  from the heart  53 , the purse string-style suture  60  is tightened or cinched around the perimeter of the catheter  51  and tied tightly therearound, and is then tied to the catheter  51  itself, as shown in  FIG. 7 . The stay sutures  61  are removed, and the chest cavity is closed. It may be desirable or necessary to place an additional stay suture (not shown) in the heart wall  65  to the side of the dimple  56 , and this stay suture may also be tied around the perimeter of the catheter  51  to provide additional securement of the catheter  51  to the heart wall  65 .  
         [0027]     The introducer  10  according to the invention effectively punctures the heart wall  65  at the dimple  56 , and creates a small, pin prick-type hole in the heart wall  65  which is much smaller than the opening through which the catheter  51  will ultimately extend into the left ventricle  54 , and the concentric muscles of the heart wall  65  are stretched open by the introducer  10  and catheter  51 . The stretched heart wall  65  adjacent the dimple  56  will then snap into a closed configuration around the catheter  51  when the introducer  10  is removed, and even during the procedure will constrict around the introducer  10  and catheter  51 , which minimizes blood loss and trauma to the heart.  
         [0028]     The introducer  10  also permits introduction of the catheter  51  into the heart  53  essentially while the opening in the heart  53  is being made, which results in a fastener introduction. Further, the introducer  10  and the catheter  51  carried therein together define a solid and essentially rod-shaped mass which fills or plugs the opening made by the introducer  10 , which also minimizes blood loss during the procedure. The smoothly-curved outer surface of nose  15  of introducer  10  also assists in penetrating the heart wall  56 .  
         [0029]     The catheter  51  once implanted within the heart  53  may be left in place only temporarily, and then removed after desired testing or drug dosing is carried out. Alternatively, the catheter  51  may be left in place permanently or for a set period of time, for example when it is desirable or necessary to carry out drug dosing at regular intervals or when it is desirable to monitor functioning of the heart  53  on a regular basis. If the catheter  51  is intended for permanent placement in the heart  53 , the outer end of the catheter  51  can be connected to an appropriate sensor or transmitter, such as a piezo-electric sensor (not shown) which may be provided subcutaneously and from which various readings can be obtained which relate to heart function. Alternatively, the outer end of the catheter  51  may exit the body of the animal and can be suitably closed off by a cap which seals the end of the catheter to the environment but is penetrable to allow drug dosing.  
         [0030]     It will be appreciated that the introducer  10  according to the invention may be utilized with animals other than canines, for example, guinea pigs, rabbits, etc., and can accordingly be scaled up or down so as to accommodate the particular animal and the size of catheter being introduced. It is contemplated that the introducer  10  pursuant to the invention may also be utilized in humans.  
         [0031]     It will be understood that the introducer  10  may be utilized to implant a catheter or other device within areas of the heart other than the left ventricle, and the illustrations and description herein relating to the left ventricle are presented as only an example of one usage of the introducer.  
         [0032]     Referring back to  FIGS. 1-3A , it is to be understood that the trough  32  need not extend along the entire longitudinal extent of the introducer  10 , and instead may terminate forwardly of rear wall  25 .  
         [0033]     The introducer  10  according to the invention may be constructed of rigid metal, such as stainless steel.  
         [0034]     Although a particular preferred embodiment of the invention is disclosed in detail for illustrative purposes, it will be recognized that variations or modifications of the disclosed apparatus, including the rearrangement of parts, lie within the scope of the present invention.