Abstract:
A catheter handpiece apparatus and method for delivering a desired dose with minimal potential for contamination of the injected substance and rapid, accurate delivery of the desired dose. In one embodiment, a carriage assembly affixed to an inner lumen is slidably located within a handpiece housing equipped with an outer lumen. The carriage assembly receives a dose carpule. An actuator knob cocks the carriage assembly and a spring-powered actuator mechanism. After the catheter is maneuvered to a desired injection site and a desired dose is set, depressing a first trigger causes the inner lumen tip to extend beyond the outer lumen into the injection site. Depressing a second trigger causes the actuator mechanism to push the desired dose from the dose carpule through the inner lumen into the injection site. A second embodiment provides a catheter handpiece with a carriage assembly cocking lever and an operator-powered dose delivery mechanism.

Description:
RELATED APPLICATIONS 
   The present invention is a continuation of U.S. patent application Ser. No. 10/171,539, filed Jun. 17, 2002, now U.S. Pat. No. 6,802,824, entitled CATHETER DEVICE AND METHOD FOR DELIVERING A DOSE INTERNALLY DURING MINIMALLY-INVASIVE SURGERY assigned to the same assignee as the present application, the entire disclosure of which is hereby incorporated by reference. 

   TECHNICAL FIELD 
   The present invention regards a catheter device and method for the delivery of medication to a desired location within a patient&#39;s body. More specifically, the present invention regards a device and method for reliable, simple and efficient delivery of a desired dose of medication to tissues within the body during minimally-invasive surgery procedures whereby a catheter handpiece is configured for deployment of a needle by the pressing of a single trigger and delivery of a desired dose of medication by pressing of another trigger. 
   BACKGROUND 
   The deployment in the body of medication and other substances, such as materials useful in tracking biological processes through non-invasive imaging techniques, is an often repeated and advantageous procedure performed during the practice of modern medicine. Such substances may be deployed in either case through non-invasive procedures such as endoscopy and through more invasive procedures that require larger incisions into the body of a patient. The non-invasive and less-invasive procedures are generally used when the target area is accessible through a lumen of the body, while the more invasive procedures may be employed when the target area is located deep within the body or otherwise not readily accessible through a lumen of the body. 
   Previously, injection of medication in minimally-invasive procedures required, among other complications, careful, time-consuming manual monitoring of the placement of the catheter tip within the body and the amount of medication or other substance being delivered during the injection procedure, potential exposure of the medication and other substances to the atmosphere during the handling of containers in preparation for dose injection, and, in the case of injection of multiple medications or other substances, time-consuming work to either remove and replace the catheter dose injection equipment or to prepare the equipment for re-use. 
   SUMMARY OF THE INVENTION 
   The present invention is directed to catheter injection systems. In one embodiment of the present invention, there is provided a drug delivery device for delivering a desired dose to an injection site within a patient&#39;s body. The device includes a catheter handpiece, wherein the catheter handpiece has an outer handpiece body and an inner carriage assembly, and the inner carriage assembly can slide between a lumen end and an opposing actuator end of the handpiece body. The carriage assembly is biased toward the lumen end of the handpiece body by a spring. The handpiece body has an aperture through which a dose carpule is inserted to rest in the carriage assembly. An outer lumen is affixed to the lumen end of the handpiece body, and an inner lumen is affixed to the lumen end of the carriage assembly, such that when the carriage assembly slides toward the lumen end of the handpiece body, the inner lumen slides within the outer lumen a sufficient distance for the distal end of the inner lumen to extend beyond the distal end of the outer lumen, exposing an injection needle tip. 
   At the lumen end of the carriage assembly there is a dose carpule receiving flange. The proximal end of the inner lumen is affixed to the lumen end of the dose carpule receiving flange, which is configured to receive the dose carpule and guide the desired dose from the dose carpule into the inner lumen when a dose delivery actuator at the actuator end of the carriage assembly causes a dose delivery actuator to push on a piston within the dose carpule. Adjacent to the lumen end of the dose actuator is a dose carpule pressing block which presses the dose carpule toward the dose carpule receiving flange when an aperture door covering the handpiece body aperture is closed. 
   The catheter handpiece is prepared for use by actuation of an actuator cocking member located at the actuator end of the handpiece body. In this embodiment, the actuator cocking member is a knob which rotates about an axis parallel to the longitudinal axis of the carriage assembly. When the actuator cocking member is rotated by an operator, the carriage assembly is pulled toward the actuator end of the handpiece body until captured by the carriage release trigger, and a dose delivery actuator tube is rotated until captured by the dose release trigger. During the movement of the carriage assembly and the dose delivery actuator tube, the dose delivery actuator rod is prevented from being retracted by a ratchet mechanism. Once the catheter is located at the desired injection site within the patient&#39;s body, the carriage release trigger may be actuated, whereupon the carriage assembly is released from its cocked position and slides toward the lumen end of the body, thereby extending the distal end of the inner lumen beyond the distal end of the outer lumen and causing the attached injection needle to penetrate the tissue at the desired injection site. Following deployment of the inner lumen, the dose release trigger may be actuated, whereupon the dose delivery actuator is released from its cocked position and a spring causes the dose actuator tube to rotate, which advances the actuator rod by means of a threaded dose delivery actuator nut through which the actuator rod passes toward the actuator end of the dose carpule. The actuator rod thus applies a force to the carpule piston to cause the desired dose to be delivered from the dose carpule through the dose carpule receiving flange and the inner lumen to the desired injection site. The amount of dose delivered is controlled by a dose metering member, which limits the motion of the dose delivery actuator tube, nut and rod, and thereby limits amount of medication discharged from the dose carpule. Following injection of the desired dose, the catheter handpiece may be cocked, withdrawing the inner lumen and injection needle back within the outer lumen. The catheter then may be repositioned to another desired injection location within the patient&#39;s body for delivery of an additional dose from the installed dose carpule in the manner described above. The dose delivery process may be repeated until the desired number of doses have been delivered from the carpule, or the carpule is spent, whichever occurs first. When no further doses are to be delivered from the dose carpule, the catheter handpiece may be cocked to withdraw the inner lumen tip into the outer lumen prior to removal of the catheter from the patient&#39;s body. 
   In a second embodiment of the present invention, the actuator is not powered by a spring, but instead the actuator rod moves toward the catheter end of the carriage assembly, thereby contacting and advancing the dose carpule piston, by manual turning of the actuator advancing knob at the actuator end of the handpiece body. Cocking of the needle release mechanism is accomplished by manual squeezing and pivoting of a cocking lever. 
   The present invention further includes a method for delivering the desired dose to a desired injection location. The method includes: (a) inserting a dose carpule through an aperture in the catheter handpiece affixed to the catheter into the carriage assembly and closing the aperture door in order to urge the dose carpule toward a receiving flange on the carriage assembly; (b) priming the inner lumen to remove air therein by setting a desired dose setting on a dose metering member in the handpiece body, rotating the actuator cocking knob on the end of the catheter handpiece opposite the catheter until the carriage assembly and the dose delivery actuator are in their respective cocked positions, depressing the carriage release trigger to cause the carriage assembly to slide toward the lumen end of the catheter handpiece, and depressing the dose release trigger to cause the dose actuator rod to apply a force to the dose carpule to cause the substance to be injected therein to pass from the dose carpule through the dose receiving flange and though the inner lumen and reach the end of the injection needle tip (this sequence is repeated until the medication reaches the injection needle tip); (c) rotating the actuator cocking knob on the end of the catheter handpiece opposite the catheter until the carriage assembly and the dose delivery actuator are in their respective cocked positions; (d) inserting the catheter including an outer lumen and an inner lumen into a patient&#39;s body and maneuvering the catheter to a desired dose injection site; (e) depressing the carriage release trigger to cause the carriage assembly to slide toward the lumen end of the catheter handpiece and thereby cause the inner lumen affixed to the carriage assembly to extend beyond the distal end of the outer lumen into the desired injection site; and (f) depressing the dose release trigger to cause the dose actuator rod to apply a force to the dose carpule to cause the desired dose to pass from the dose carpule through the dose receiving flange, though the inner lumen and its injection needle tip and be deposited at the desired injection site. Alternatively, instead of depressing a dose release trigger, when using a non-spring powered embodiment of the present invention, the operator may advance the dose actuator rod toward the dose carpule by manually rotating the actuator advancing knob. Following dose delivery, the catheter handpiece may be cocked, withdrawing the inner lumen and injection needle back within the outer lumen. The catheter then may be repositioned to another desired injection location within the patient&#39;s body for delivery of an additional dose by resetting the desired dose, depressing the needle release trigger, and depressing the dose release trigger or, in the second embodiment, turning the actuator advancing knob in the manner described above. The dose delivery process may be repeated until the desired number of doses have been delivered from the carpule or the carpule is spent, whichever occurs first, at which point the catheter handpiece may be cocked to withdraw the inner lumen tip into the outer lumen prior to removal of the catheter from the patient&#39;s body. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side view of a catheter handpiece in accordance with a first embodiment of the present invention. 
       FIG. 2  is a view of the internal arrangement of a lower portion of the catheter handpiece housing and the carriage assembly in accordance with a first embodiment of the present invention. 
       FIG. 3  is a view of an upper portion of the catheter handpiece housing and the dose carpule insertion aperture door in accordance with a first embodiment of the present invention. 
       FIG. 4  is a view of the carriage assembly in accordance with a first embodiment of the present invention. 
       FIG. 5  is an exploded view of the carriage assembly showing components which cooperate with the dose delivery actuator to permit its operation in accordance with a first embodiment of the present invention. 
       FIG. 6  is an oblique view of a catheter handpiece in accordance with a second embodiment of the present invention. 
       FIG. 7  is an oblique phantom view of a catheter handpiece and its carriage assembly in accordance with an second embodiment of the present invention. 
       FIG. 8  is an exploded view of the carriage assembly in accordance with a second embodiment of the present invention. 
   

   DETAILED DESCRIPTION 
   FIRST EMBODIMENT 
     FIG. 1  is a side view of a catheter handpiece  1  of a first embodiment of the present invention. The handpiece housing  2  in this embodiment may be made from any biocompatible and sufficiently rigid material including plastic and hard rubber. As shown in  FIG. 1 , catheter handpiece  1  has at its actuator end  3  an actuator knob  4  for cocking the catheter handpiece. Toward catheter handpiece lumen end  5 , there is a dose carpule insertion aperture  6  with an aperture door  7 . In this embodiment, there is also provided near dose carpule insertion aperture  6  a rubber grip surface  8  to enhance operator control of the handpiece. Toward actuator end  3  of the catheter handpiece there is a dose metering member  9  which is used to set the amount of dose desired to be injected into the patient when the catheter handpiece is activated. Next to dose metering member  9  is a replaceable dose metering label  10  to provide the operator with an indication of the amount of dose that will be injected at various settings of dose metering member  9 . Dose metering label  10  may be replaced as necessary to ensure the dose selected with dose metering member  9  corresponds to the dose delivered by the particular dose carpule being used. 
     FIG. 1  further shows a catheter affixed at its proximal end to the lumen end  5  of the handpiece, comprising an outer lumen  11  and a strain relief member  12 . An inner lumen resides within outer lumen  11 , and is affixed at its proximal end to a carriage assembly slidably located within handpiece housing  2  (inner lumen  13  and carriage assembly  14  are shown in  FIG. 2  and discussed further, below). The catheter is inserted into a patient&#39;s body and maneuvered to the desired injection site using techniques well known to practitioners. Once properly positioned, a carriage assembly release trigger  15  releases carriage assembly  14 , which slides toward lumen end  5  of catheter handpiece  1  and thereby extends the distal end of inner lumen  13  and an injection needle tip at the end thereof (not shown) beyond the distal end of outer lumen  11  and into tissue at the desired dose injection site. Catheter handpiece  1  also contains a dose delivery actuator trigger  16 , which releases a dose delivery actuator within the carriage assembly to permit a dose delivery actuator rod to apply a force to a dose carpule  17  (specifically, to carpule piston  17 B), thereby causing the desired dose to pass from the dose carpule through inner lumen  13  to the desired injection site (dose delivery actuator  18  and dose carpule  17  are shown in  FIG. 2 ). 
     FIG. 2  is a view of the internal arrangement of a portion of the catheter handpiece housing  1  and carriage assembly  14  in accordance with a first embodiment of the present invention. As shown in  FIG. 2 , carriage assembly  14  is slidably located within handpiece housing member  19  such that carriage assembly  14  can slide between lumen end  5  and actuator end  3  of the catheter handpiece housing. A spring  20  is connected at one end to carriage assembly  14  and at its other end to handpiece housing member  19 , and biases carriage assembly  14  toward lumen end  5  of the catheter handpiece housing. At the carriage assembly&#39;s lumen end  21  there is a dose carpule receiving flange  22 , to which the proximal end of inner lumen  13  is affixed. As in  FIG. 1 , outer lumen  11  is shown affixed via strain relief member  12  to lumen end  5  of handpiece housing member  19 . 
   The face of dose carpule receiving flange  22  opposite inner lumen  13  is tapered to receive a mating tapered protrusion (not shown) at the front of dose carpule  17  when the carpule is inserted into carriage assembly  14 . Once in the carriage assembly, dose carpule  17  is urged into mating contact with dose carpule receiving flange  22  by dose carpule pressing block  23 . Referring now to  FIGS. 2 and 3 , dose carpule pressing block  23  has grooves  24  which engage corresponding engagement pins  25  on handpiece housing aperture door  7 , which is slidably located within a second handpiece housing member  26  such that aperture door  7  may slide beneath aperture  6  between open and closed positions by applying pressure on door operating tab  27 . As aperture door  7  is moved from the open position to the closed position, door pins  25  engaged in dose carpule pressing block grooves  24  cause dose carpule pressing block  23  to pivot on carriage assembly  14  about pivot pins  28 . Pressing block  23  thus rotates toward, and begins pressing against, the end of dose carpule  17 . This motion in turn urges dose carpule  17  into mating contact with dose carpule receiving flange  22  with a locking cam action. As aperture door  7  continues toward the closed position, door pins  25  disengage from dose carpule pressing block grooves  24 . In  FIG. 2 , dose carpule pressing block  23  is shown in its disengaged position. In  FIG. 4 , dose carpule pressing block  23  is shown in its fully engaged position, pressing dose carpule  17  into mating contact with dose carpule receiving flange  22 . 
   Referring again to  FIG. 2 , located between dose carpule  17  and actuator end  29  of the carriage assembly is dose delivery actuator rod  18 , the operating mechanism for which will be described further, below. Dose delivery actuator rod  18  is positioned on carriage assembly  14  such that when actuated, the actuator moves toward dose carpule  17 , through dose carpule pressing block  23 , and applies a force to dose carpule piston  17 B that causes the medication in dose carpule  17  to pass from the carpule through dose carpule receiving flange  22  and inner lumen  13 , into the desired injection site within the patient&#39;s body. 
   Also shown in  FIG. 2  is actuator knob  4  at actuator end  3  of handpiece housing member  19 . Actuator knob  4  is located by a flange adjacent to the end of housing member  19 , such that the knob may be rotated about an axis parallel to a longitudinal axis of carriage assembly  14 . Actuator knob  4  has around its outer periphery a spring  30  attached at one end to actuator knob  4  and at its other end to handpiece housing member  19 , such that spring  30  returns actuator knob  4  to a rest position following the knob&#39;s use to cock the catheter handpiece prior to dose delivery. The inner diameter of actuator knob  4  is sufficiently large to surround the actuator end  29  of carriage assembly  14 . 
   Additional features shown in  FIG. 2  include dose metering member  9 , which in this embodiment is captured between the two catheter handpiece housing members  19  and  26  during assembly of the housing. Dose metering member  9  is configured such that its inner surface cooperates with the carriage assembly&#39;s actuator mechanism to limit the travel of the dose delivery actuator, and thus dose delivery actuator rod  18 , thereby limiting the dose delivered from dose carpule  17  to the injection site dose. Specifically, the inner surface of dose metering member  9  has a graduated stepped surface which, in combination with a dose stop tab on the dose delivery actuator mechanism, limits dose delivery to specific, discrete quantities. 
   Also shown in  FIG. 2  are carriage release trigger  15  and carriage assembly cocking tab  31 . Upon cocking catheter handpiece  1 , carriage assembly  14  slides toward the actuator end of handpiece housing  19  until a carriage assembly cocking tab  31  is caught and releasably held by carriage release trigger  15 . 
     FIG. 5  shows an exploded view of carriage assembly actuator mechanism. Carriage assembly  14  has a lower member  32  and upper member  33  between which the components of the dose delivery actuator mechanism reside. On the outside of carriage assembly members  32  and  33 , adjacent to actuator end  29 , is a stepped helical ridge  34 . Helical ridge  34  cooperates with a corresponding tab within the inner diameter of actuator knob  4  (not shown) such that as actuator knob  4  is rotated, the tab within the knob slides along ridge  34 , pulling carriage assembly  14  toward the actuator end  3  of catheter handpiece  1  until dose carriage cocking tab  31  is captured by carriage assembly release trigger  15 . 
   The following describes the arrangement and operation of the dose delivery actuator in the first embodiment of the present invention. Dose delivery actuator rod  18  in this embodiment has external threads along its length which engage corresponding internal threads in a hole in the center of dose delivery actuator nut  35 . Actuator nut  35  also has a circumferential groove  36  that rests against indexing surfaces  37  in the interior of carriage assembly members  32  and  33  (indexing surface within member  33  not shown) and the face  38  of actuator tube  39 , such that actuator nut  35  is constrained from moving toward the lumen end  21  or actuator end  29  of the carriage assembly. As a result of this arrangement, actuator nut  35  may only rotate about the longitudinal axis of dose delivery actuator rod  18 . Due to the interaction between the threads on dose delivery actuator rod  18  and the threads in actuator nut  35 , when actuator nut  35  rotates about dose delivery actuator rod  18 , the actuator rod moves toward lumen end  21 . 
   Actuator nut  35  further has ratchet teeth  40  formed on both sides of its outer circumference adjacent to circumferential groove  36 . Actuator nut ratchet teeth  40  are releasably engaged, on one side of circumferential groove  36  by the engagement of a ratchet pawl  45  on carriage assembly member  33 , and on the other side of the nut by corresponding ratchet hooks  41  within the face of lumen end of actuator tube  39 . The actuator nut ratchet teeth  40  on both sides of circumferential groove  36  are arranged in same direction, such that when ratchet pawl  45  is engaged with one row of teeth  40 , actuator nut  35  cannot rotate in a clockwise direction viewed from the lumen end of the carriage assembly. 
   Dose delivery actuator rod  18  has at its actuator end a square-head  42  which engages a corresponding recess within substantially the entire length of dose delivery actuator drive nut  43 . Actuator drive nut  43  in turn rests concentrically within dose delivery actuator spring  44  and dose delivery actuator tube  39 . One end of actuator spring  44  engages holes in tabs  46  on the end of actuator drive nut  43 , while the other end of the spring engages a hole on an interior surface within actuator tube  39 , such that when actuator tube  39  is turned relative to actuator drive nut  43 , energy is stored in actuator spring  44 . Engagement tabs  46  at the end of actuator drive nut  43  also serve to engage actuator drive nut slot  47  in carriage assembly lower member  32 , such that dose drive nut  43  cannot rotate relative to carriage assembly  14 . 
   The dose delivery actuator is cocked by turning actuator knob  4 , which is internally configured to simultaneously cooperate with the end of actuator tube  39  and carriage assembly  14 . As actuator knob  4  is turned counter-clockwise viewed from the lumen end of carriage assembly  14 , the carriage assembly is drawn toward the actuator end of catheter handpiece housing  1  and releasably held by carriage assembly release trigger  15  in the manner previously described. Simultaneously, the counter-clockwise rotation of actuator knob  4  rotates actuator tube  39 , causing ratchet teeth  41  on the face of actuator tube  39  to ratchet over ratchet teeth  40  on actuator nut  35 , storing energy in spring  44 , while also permitting dose delivery actuator trigger  16  to capture actuator tube  39  in its cocked position. Actuator nut  35  is prevented from rotating with actuator tube  39  by the engagement of ratchet pawl  45  on carriage assembly member  33  with the distal teeth of actuator nut  35 . The pitch of the internal and external threads of actuator nut  35  and dose delivery actuator rod  18  are selected to achieve the desired range of axial motion of dose delivery actuator rod  18  within a relatively short arc of actuator tube  39  rotation when the stored energy in spring  44  is released by activating dose release trigger  16 . 
   Upon reaching the fully cocked position, release of actuator knob  4  by the operator will result in actuator knob biasing spring  30  rotating the knob clockwise back to its rest position. After the cocking of the catheter handpiece and before triggering dose delivery, the desired dose setting may be set by sliding dose metering member  9  to the appropriate dose setting as indicated on dose label  10 . 
   The following describes the operation of the dose delivery actuator to deliver the desired dose after the actuator mechanism is cocked in the manner described above. Following release of carriage assembly  14  from its cocked position by depression of carriage release trigger  15 , an operator may depress dose delivery trigger  16  to cause the desired dose to be delivered. Depression of dose delivery trigger  16  causes its hook end to pivot clear of actuator tube  39 . Due to the energy stored in actuator spring  44 , actuator tube  39  and actuator nut  35  (which are engaged by ratchet teeth  40  and  41 ) begin to rotate clockwise. The clockwise rotation of actuator nut  35  drives dose delivery actuator rod  18  toward, and into contact with, carpule piston  17 B, forcing at least a portion of the contents of the carpule into dose carpule receiving flange  22  and thence through inner lumen  13  to the desired injection site. The clockwise rotation of actuator nut  35  and axial motion of dose delivery actuator rod  18  continue until dose metering stop tab  50  reaches the step on inner surface of dose metering member  9  corresponding to the desired dose. When dose metering stop tab  50  reaches the selected dose stop step, the clockwise rotation of actuator tube  39  and actuator nut  35  and the axial motion of dose delivery actuator rod  18  toward the lumen end of carriage assembly  14  are halted, completing the delivery of the desired dose. 
   Associated with the foregoing embodiment of the present invention is a method for delivery of a desired dose using a catheter handpiece of significantly simplified operation. In preparation for delivery of a desired dose of medication or other substance, such as an imaging agent, to a desired injection site within a patient&#39;s body, the catheter handpiece of the first embodiment may be prepared for use by placing a dose carpule containing the substance to be injected into the patient through carpule insertion aperture  6  and into carriage assembly  14 , and then closing aperture door  7  to cause the dose carpule to be urged into mating contact with dose carpule receiving flange  22 . At this time, adhesive dose metering label  10  may be affixed to the catheter handpiece body adjacent to dose metering member  9  to guide the setting of the desired dose to be injected, and dose metering member  9  may be set to the desired dose. 
   Next, the catheter handpiece operator cocks the catheter handpiece by gripping the handpiece in one hand and using the other hand to rotating actuator knob  4  clockwise viewed from the actuator knob end of the handpiece until the dose actuator mechanism in carriage assembly  14  reaches the end of its travel and actuator knob  4  stops. Upon release of actuator knob  4  by the operator, the knob rotates counter-clockwise back to its starting position. 
   Next, the operator depresses carriage assembly release trigger  15  and dose delivery trigger  16  to prime the inner lumen with the substance to be injected. The cocking and firing sequence may be repeated until the substance to be injected has reached the distal end of inner lumen  13 . Once primed, the catheter handpiece may be re-cocked in the manner previously described and the physician may insert the catheter, comprising outer lumen  11  and inner lumen  13 , into the patient&#39;s body and maneuver the catheter to the desired injection site in the conventional manner. 
   Once the catheter is located at the desired injection site, the catheter operator may depress carriage assembly release trigger  15  to cause carriage assembly  14  to slide forward and thus cause the distal end of inner lumen  13  to extend beyond outer lumen  11  into the desired injection site. Once inner lumen  13  has been deployed at the desired injection site, the catheter operator may depress dose delivery trigger  16 , thereby permitting dose delivery actuator rod  18  to press on the dose carpule piston  17 B and thereby cause the desired dose to pass from the dose carpule through dose carpule receiving flange  22  and into inner lumen  13 , and thence into the desired injection site. Following delivery of the desired dose, the catheter handpiece may be cocked, withdrawing the inner lumen and injection needle back within the outer lumen. The catheter then may be repositioned to another desired injection location within the patient&#39;s body for delivery of an additional dose in the manner described above. The dose delivery process may be repeated until the desired number of doses have been delivered from the carpule or the carpule is spent, whichever occurs first, at which point the catheter may be removed from the patient&#39;s body. 
   SECOND EMBODIMENT 
   The second embodiment of the present invention shares the majority of the principal features of the first embodiment, with differences in detail principally due to the second embodiment&#39;s dose delivery actuator being deployed manually by the operator, rather than, as in the first embodiment, by utilizing stored spring energy to deploy the dose delivery actuator. 
     FIG. 6  is an oblique view of a catheter handpiece in accordance with a second embodiment of the present invention, showing catheter handpiece  101 , with a lumen end  102  and an actuator end  103 . As in the first embodiment, handpiece housing  104  may be made from any bio-compatible and sufficiently rigid material including plastic and hard rubber. At its actuator end  103 , catheter handpiece  101  has an actuator knob  105  for operating the dose delivery actuator mechanism within the catheter handpiece and thereby delivering the desired dose. Toward lumen end  102 , there is a dose carpule insertion aperture  106  with an aperture door  107 , and a dose metering member  108  which is used to set the amount of dose desired to be injected into the patient when the catheter handpiece is activated. Next to dose metering member  108  are dose metering markings  109  to provide the operator with an indication of the amount of dose that will be injected at various settings of dose metering member  108 . 
     FIG. 6  further shows a catheter affixed at its proximal end to the lumen end  102  of the handpiece, comprising an outer lumen  110  and a strain relief member  111 . An inner lumen resides within outer lumen  110 , and is affixed at its proximal end to a carriage assembly slidably located within handpiece housing  104  (inner lumen  112  and carriage assembly  113  are shown in  FIG. 7  and discussed further, below). Once the catheter is properly positioned in the patient&#39;s body, carriage assembly release trigger  114  releases carriage assembly  113 , which slides toward lumen end  102  of catheter handpiece  101  and thereby extends the distal end of inner lumen  112  and an injection needle tip at the end thereof (not shown) beyond the distal end of outer lumen  110  and into tissue at the desired dose injection site. Catheter handpiece  101  also contains a handpiece cocking lever  115 , which moves carriage assembly  113  into its cocked position. Dose carpule  116  (shown in  FIG. 7 ) is inserted into catheter handpiece  101  through aperture  106  and placed in carriage assembly  113  with carriage assembly  113  in the uncocked position. 
   Reference will now be made to  FIG. 7  and  FIG. 8  to highlight the principal differences in arrangement and operation of the second embodiment from the first embodiment (arrangements or operations which are similar between the two embodiments are not again described herein).  FIG. 7  is an oblique phantom view of a catheter handpiece and its carriage assembly in accordance with the second embodiment of the present invention, while  FIG. 8  is an exploded view of the carriage assembly of the second embodiment. 
   As shown in  FIG. 7 , carriage assembly  113  is slidably located within handpiece housing  104  such that carriage assembly  113  can slide between lumen end  102  and actuator end  103  of the catheter handpiece housing. A spring  117  is connected at one end to carriage assembly  113  and at its other end to handpiece housing  104 , and biases carriage assembly  113  toward lumen end  102  of the catheter handpiece housing. At the carriage assembly&#39;s lumen end  118  there is a dose carpule receiving flange  119 , to which the proximal end of inner lumen  112  is affixed. Outer lumen  110  is shown affixed via strain relief member  111  to lumen end  102  of handpiece housing  104 . 
   As in the first embodiment, a dose delivery actuator rod  120  is located between dose carpule  116  and actuator end  121  of the carriage assembly. Dose delivery actuator rod  120  is positioned on carriage assembly  113  such that when actuated, the actuator moves toward dose carpule  116  and applies a force to carpule piston  116 B that causes the medication therein to pass from dose carpule  116  through dose carpule receiving flange  119  and inner lumen  112  to reach the desired injection site within the patient&#39;s body. 
   Additional features shown in  FIG. 7  include actuator knob  105  at actuator end  103  of handpiece housing  104 . As shown in  FIG. 8 , actuator knob  105  has an internal projection  122  extending from its center toward carriage assembly  113 , which contains an axial hexagonal hole. Actuator knob  105  is coupled to the catheter handpiece through the fitting of an axial hexagonal hole in projection  122  over a corresponding hexagonal end projection  123  of dose delivery actuator tube  124 , and by trapping of a groove  154  in projection  122  between the halves of the handpiece body. Actuator knob  105  is returned to its rest position after use by a spiral spring  153  concentrically located over internal projection  122 . One end of spring  153  engages a hole in the underside of actuator knob  105 , while the other end of spring  153  engages a hole in handpiece housing  104  (shown in  FIG. 7 ). 
   Returning to  FIG. 7 , also shown are a number of components whose operation will be described further, below, including handpiece cocking lever  115 , which is pivotally mounted to handpiece housing  104 , pushing arm  125  configured to pivot with handpiece cocking lever  115  and pushes carriage assembly  113  into its cocked position, actuator tube holdback ratchet lever  126 , carriage release trigger  114 , and carriage assembly tab  127 , which is releasably captured by carriage release trigger  114  as the catheter handpiece is cocked. Within the inner surface of handpiece housing  104  toward, its actuator end  103  is dose delivery blocking ridge  128 , which cooperates with dose tube safety tab  129  when carriage assembly  113  is in its cocked position to prevent delivery of a dose from dose carpule  116  if inner lumen  112  has not been deployed. Finally,  FIG. 7  shows dose tube stop tab  130  projecting outward through slot  131  in carriage assembly  113  from outside of actuator tube  124 . Dose stop tube tab  130  interacts with dose metering steps on an inner surface of dose metering member  108  (not shown) to halt dose delivery when the desired amount of medication or other substance has been delivered to the desired injection location within the patient. 
     FIG. 8  shows an exploded view of carriage assembly actuator mechanism of the second embodiment. Carriage assembly  113  has a lower member  132  and upper member  133  between which the components of the dose delivery actuator mechanism reside. On the underside of carriage assembly member  132  is a carriage cocking bar  134 . When handpiece cocking lever  115  is depressed, pushing arm  125  pivots, pushing carriage cocking bar  134  and carriage assembly  113  toward actuator end  103  of the catheter handpiece until carriage cocking tab  127  on carriage assembly member  133  is releasably captured by carriage release trigger  114  (shown in  FIG. 7 ). At the beginning of the stroke of handpiece cocking lever  115 , the initial motion of the lever results in contact with actuator tube holdback ratchet lever  126  (shown in  FIG. 7 ), which is pivotally mounted on carriage assembly  113  such that its holdback pawl passes through slot  135  in carriage assembly  113  and engages actuator tube ratchet teeth  136 , thereby preventing clockwise rotation of actuator tube  124 . When handpiece cocking lever  115  contacts actuator tube holdback ratchet lever  126 , the lever pivots and disengages actuator tube ratchet teeth  136 , permitting the actuator tube to rotate clockwise to ensure it is in its starting position in the dose delivery process. 
   The following describes the arrangement of the dose delivery actuator in the second embodiment of the present invention. As in the first embodiment, dose delivery actuator rod  120  has external threads along its length which engage corresponding internal threads in a hole in the center of actuator nut  137 . Actuator nut  137  rests against indexing surfaces  138  in the interior of carriage assembly members  132  and  133  (indexing surface within member  133  not shown) and the face  139  of actuator tube  124 , such that actuator nut  137  is constrained from moving toward the lumen end  118  or actuator end  121  of the carriage assembly. As with the first embodiment, actuator nut  137  may only rotate about the longitudinal axis of dose delivery actuator  120 , and actuator nut  137  and dose delivery actuator rod  120  cooperate to permit extension of actuator rod  120 . 
   Actuator nut  137  further has ratchet teeth  140  formed on both sides of its outer circumference adjacent to circumferential groove  141 . Actuator nut ratchet teeth  140  are releasably engaged, to one side of circumferential groove  141  by a hook  150  on carriage assembly member  133 , and to the other side of the nut by corresponding ratchet hooks  142  within the face of lumen end of actuator tube  124 . The actuator nut ratchet teeth  140  on both sides of circumferential band  141  are arranged in the same direction, such that when the ratchet hooks are engaged, actuator nut  137  cannot rotate in a clockwise direction viewed from the lumen end of the carriage assembly. 
   Dose delivery actuator rod  120  has at its actuator end a square-shaped head  143  which engages a corresponding recess within substantially the entire length of dose delivery actuator drive nut  144 . Actuator drive nut  144  in turn rests concentrically within actuator tube  124 . Along the exterior circumference of actuator drive nut  144  are drive nut holding tabs  145 , which pass through slots  146  in actuator tube  124  and engage corresponding recesses in the interior surface of carriage assembly member  133  (not shown) to prevent rotation of drive nut  144  during operation of catheter handpiece  101 . 
   Also shown in  FIG. 8  is dose metering stop tab  130  extending radially from the outside circumference of actuator tube  124  through dose stop slot  131  in carriage assembly member  133 . Dose metering stop tab  130  is positioned along actuator tube  124  such that when the dose delivery operation is performed, the dose stop tab contacts dose metering member  108  and stops further dose injection when the desired dose is reached. 
   Operation of the catheter handpiece of the second embodiment begins with the operator depressing handpiece cocking lever  113 , which simultaneously causes carriage assembly  113  to slide toward the actuator end  103  of catheter handpiece  101  until carriage assembly tab  127  is captured and releasably held by carriage assembly release trigger  114 , and causes actuator tube holdback lever  126  to pivot, thereby releasing actuator tube  124  to rotate clockwise by force of actuator knob spring  153  to return to its rest position and to permit dose tube safety tab  129  to engage dose delivery blocking ridge  128 , thereby preventing dose delivery while the handpiece is cocked. 
   Following a physician&#39;s insertion of the catheter into the patient&#39;s body and maneuvering of the catheter to the desired injection site, the operator depresses carriage assembly release trigger  114 , freeing carriage assembly  113  to slide toward lumen end  102  of catheter handpiece  101 , thereby extending the injection needle tip on the distal end of inner lumen  112  into the desired injection site. The movement of carriage assembly  113  toward lumen end  102  also allows dose tube safety tab  129 , which extends from actuator tube  124 , to pass dose delivery blocking ridge  128  and thereby permit actuator tube  124  to subsequently rotate counter-clockwise when operated. In order to deliver the desired dose, actuator knob  105  is manually rotated counter-clockwise by the operator, which in turn rotates actuator tube  124  (to which actuator knob  105  is coupled by engagement of knob projection  122  with actuator tube  123 ) counter-clockwise until dose metering stop tab  130  projecting from the outer surface of actuator tube  124  reaches the inner surface of dose metering member  108 . As in the first embodiment, the range of travel of the actuator tube  124  is relatively short (approximately 45 degrees), however, any length of arc less than a complete circle could be used as long as the length of dose stop slot  152  is not so great as to compromise the structural integrity of the carriage assembly. 
   The counter-clockwise rotation of actuator tube  124  causes actuator nut  137  (whose ratchet teeth  140  are engaged by ratchet hooks  142  on face  139  of actuator tube  124 ) to also rotate counter-clockwise with actuator tube  124 . Due to the interaction of the internal threads of actuator nut  137  with the external threads on dose delivery actuator rod  120 , actuator nut  137  drives dose delivery actuator rod  120  toward, and into contact with, dose carpule piston  116 B. Dose delivery actuator rod  120  then presses on dose carpule piston  116 B to begin forcing the contents of the carpule into dose carpule receiving flange  119  and thence through inner lumen  112  and the injection needle tip into the desired injection site. The counter-clockwise rotation of actuator nut  137  and axial motion of dose delivery actuator rod  120  continues until dose metering stop tab  130  reaches the step on inner surface of dose metering member  108  corresponding to the desired dose. When dose metering stop tab  130  reaches the selected dose stop step, the counter-clockwise rotation of actuator tube  124  and actuator nut  137  and the axial motion of dose delivery actuator rod  120  toward the lumen end of carriage assembly  113  are halted, completing the delivery of the desired dose. 
   Associated with the foregoing embodiment of the present invention is a method for delivery of a desired dose using the catheter handpiece of this embodiment. In order to deliver a desired dose of medication or other substance to a desired injection site within a patient&#39;s body, the catheter handpiece of the second embodiment is be prepared for use by placing a dose carpule containing the substance to be injected into the patient through carpule insertion aperture  106  and onto carriage assembly  113 , and then closing aperture door  107 . Next, in order to prime the inner lumen with the substance to be injected, a sequence of operating cocking lever  115 , pressing carriage assembly release trigger  114  and rotating actuator advance knob  105  is performed as many times as necessary to cause the substance to be injected to reach the distal end of inner lumen  112 . 
   Once the substance has reached the end of the inner lumen, the catheter handpiece may be re-cocked in the manner previously described and dose metering member  108  set to the desired dose, whereupon the physician may then insert the catheter, comprising outer lumen  110  and inner lumen  112 , into the patient&#39;s body and maneuver the catheter to the desired injection site in the conventional manner. Once the catheter is located at the desired injection site, the catheter operator may depress carriage assembly release trigger  114  to cause carriage assembly  113  to slide forward and thus cause the distal end of inner lumen  112  to extend beyond outer lumen  110  into the desired injection site. Once inner lumen  112  has been deployed, the catheter operator may rotate actuator knob  105  counter-clockwise viewed from lumen end  102  until dose stop tab  130  on actuator tube  124  reaches the dose stop step on dose metering member  108  corresponding to the desired dose. Rotation of actuator knob  105  causes actuator tube  124  to rotate actuator nut  137  counter-clockwise, in turn causing dose delivery actuator rod  120  to extend forward to press on dose carpule piston  116 B, and thereby cause the desired dose to pass from the dose carpule through dose carpule receiving flange  119  and inner lumen  112 , and thence to the desired injection site within the patient&#39;s body. Following delivery of the desired dose, the physician may cock the catheter handpiece to withdraw the inner lumen tip into the outer lumen, and then may remove the catheter from the patient&#39;s body, or alternatively, if the contents of the dose carpule have not all been injected, and another dose may be delivered to a desired injection site. 
   While the present invention has been described with reference to what are presently considered to be preferred embodiments thereof, it is to be understood that the present invention is not limited to the disclosed embodiments or constructions. On the contrary, the present invention is intended to cover various modifications and equivalent arrangements. In addition, while the various elements of the disclosed invention are described and/or shown in various combinations and configurations, which are exemplary, other combinations and configurations, including more, less or only a single embodiment, are also within the spirit and scope of the present invention.