Abstract:
Aspects of the present disclosure are directed toward apparatuses, methods, and systems comprising an introducer apparatus for facilitating subcutaneous implantation of a medical device. The introducer apparatus may include a housing and an inserter configured to disengage from the second portion.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to Provisional Application No. 62/322,236, filed Apr. 13, 2016, which is herein incorporated by reference in its entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    The present disclosure relates to medical devices and methods for creating a pocket in a patient for an implantable medical device. More specifically, the disclosure relates to devices and methods for facilitating implantation of the implantable medical device under the patient&#39;s skin. 
       BACKGROUND 
       [0003]    Medical devices may be implanted subcutaneously under a patient&#39;s skin with relatively little intervention and without deeply positioning the device in the patient&#39;s body. Positioning of the medical device may be difficult due to high insertion forces necessary to manipulate the medical device and form a pocket for the device under the patient&#39;s skin. Improperly positioning functional aspects of the device may result in poor performance. This may include forming a pocket that is too large for the medical device, or forming a pocket having improper dimensions. In addition, improper pocket formation may result in difficult placement of the implantable medical device during the operation and/or the implantable medical device being ejected prior to sealing the pocket (e.g., stitching the incision). Further, improper pocket formation may result in an implanted device being ejected from a patient as a result of the patient&#39;s normal movement. Thus, there is a need for an introducer device that allows for improved pocket formation and positioning of an implantable medical device within the pocket. 
       SUMMARY 
       [0004]    In Example 1, an introducer apparatus for facilitating subcutaneous implantation of a medical device, the apparatus comprising: a housing having a proximal end and a distal end, the housing defining a distal opening at or adjacent to the distal end; and an inserter configured to form a subcutaneous pocket in tissue of a patient and to move the medical device through the distal opening of the housing, the inserter having a first portion configured to facilitate forming the subcutaneous pocket, and a second portion configured to facilitate moving the medical device through the distal opening of the housing, and, the first portion being configured to disengage from the second portion. 
         [0005]    In Example 2, the apparatus of Example 1, wherein the housing comprises a proximal opening and a first channel between the proximal opening and the distal opening along a length of the housing, and each of the first portion and the second portion are configured to move within the first channel along the length of the housing, and wherein the inserter configured to form the subcutaneous pocket without rotation of the housing or the inserter. 
         [0006]    In Example 3, the apparatus of any of Examples 1-2, wherein the first portion comprises a proximal end and a distal end, a first handle portion arranged at the proximal end of the first portion, and a first extension portion extending from the first handle portion. 
         [0007]    In Example 4, the apparatus of Example 3, wherein the second portion comprises a proximal end and a distal end, a second handle portion arranged at the proximal end of the second portion, a second extension portion extending from the second handle portion, and the second portion comprises a second channel along a length of the second extension portion. 
         [0008]    In Example 5, the apparatus of Example 4, wherein the first portion is configured to move within the second channel. 
         [0009]    In Example 6, the apparatus of Example 5, wherein the first handle portion comprises a first upper surface and a first lower surface, the second handle portion comprises a second upper surface and a second lower surface, and the first lower surface and the second upper surface are corresponding surfaces. 
         [0010]    In Example 7, the apparatus of Example 6, wherein the first handle portion is configured to nest within the second handle portion. 
         [0011]    In Example 8, the apparatus of Example 4, wherein the first extension portion has a first length, and the second extension portion has a second length, and the first length is greater than the second length. 
         [0012]    In Example 9, the apparatus of Example 8, wherein each of the first extension portion and the second extension portion are configured to extend through the distal opening of the housing in a fully-extended configuration of the first portion and the second portion. 
         [0013]    In Example 10, the apparatus of Example 9, wherein the second extension portion is configured to extend through the distal opening of the housing in a fully-extended configuration of the second portion after the first portion is disengaged from the second portion. 
         [0014]    In Example 11, the apparatus of any of Examples 1-10, wherein the second portion includes lateral extensions configured to prevent the second portion from disengaging from the housing. 
         [0015]    In Example 12, the apparatus of any of Examples 1-11, further including a removable lock structure configured to hold the first portion and the second portion relative to the housing in an initial configuration. 
         [0016]    In Example 13, the apparatus of Example 12, wherein the housing includes a proximal opening and a first channel between the proximal opening and the distal opening along a length of the housing, and each of the first portion and the second portion are configured to move within the first channel along the length of the housing after removal of the removable lock structure. 
         [0017]    In Example 14, the apparatus of any of Examples 2-13, wherein the housing comprises a compartment laterally adjacent to the first channel, wherein the compartment is configured to releasably hold and contain the medical device. 
         [0018]    In Example 15, the apparatus of any of Examples 1-14, wherein the inserter is configured to form the subcutaneous pocket without rotation of the housing or the inserter. 
         [0019]    In Example 16, a housing having a proximal end and a distal end, the housing defining a distal opening at or near the distal end; a tunneler configured to facilitate forming a subcutaneous pocket for the medical device and extend from the distal end of the housing; and an inserter configured to form the subcutaneous pocket in tissue of a patient and to move the medical device through the distal opening of the housing, the inserter having a first portion configured to facilitate forming the subcutaneous pocket, and a second portion configured to facilitate moving the medical device through the distal opening of the housing, and, the first portion being configured to disengage from the second portion. 
         [0020]    In Example 17, the apparatus of Example 16, wherein the inserter is configured to form the subcutaneous pocket without rotation of the housing or the inserter. 
         [0021]    In Example 18, the apparatus of Example 16, wherein the first portion of the inserter comprises a proximal end and a distal end, and a first handle portion arranged at the proximal end of the first portion. 
         [0022]    In Example 19, the apparatus of Example 17, wherein the second portion comprises a proximal end and a distal end, and a second handle portion arranged at the proximal end of the second portion. 
         [0023]    In Example 20, the apparatus of Example 18, wherein the first handle portion comprises a first upper surface and a first lower surface, the second handle portion comprises a second upper surface and a second lower surface, and the first lower surface and the second upper surface are corresponding surfaces. 
         [0024]    In Example 21, the apparatus of Example 19, wherein the first handle portion is configured to nest within the second handle portion. 
         [0025]    In Example 22, the apparatus of Example 16, wherein the housing comprises a proximal opening and a first channel between the proximal opening and the distal opening along a length of the housing, and each of the first portion and the second portion are configured to move within the first channel along the length of the housing. 
         [0026]    In Example 23, the apparatus of Example 22, wherein the second portion comprises a second channel along a length thereof, and wherein the first portion is configured to move within the second channel. 
         [0027]    In Example 24, the apparatus of Example 16, wherein the first portion of the inserter comprises a proximal end and a distal end, a first handle portion arranged at the proximal end of the first portion, and a first extension portion extending from the first handle portion. 
         [0028]    In Example 25, the apparatus of Example 24, wherein the second portion comprises a proximal end and a distal end, and a second handle portion arranged at the proximal end of the second portion, and a second extension portion extending from the second handle portion. 
         [0029]    In Example 26, the apparatus of Example 25, wherein the first extension portion has a first length, and the second extension portion has a second length, and the first length is greater than the second length. 
         [0030]    In Example 27, the apparatus of Example 26, wherein each of the first extension portion and the second extension portion are configured to extend through the distal opening of the housing in a fully-extended configuration of the first portion and the second portion. 
         [0031]    In Example 28, the apparatus of Example 27, wherein the second extension portion is configured to extend through the distal opening of the housing in a fully-extended configuration of the second portion after the first portion is disengaged from the second portion. 
         [0032]    In Example 29, a system comprising: a medical device; and an introducer apparatus for facilitating subcutaneous implantation of the medical device, the apparatus comprising: a housing having a proximal end and a distal end, the housing defining a distal opening at or adjacent to the distal end, a tunneler configured to facilitate forming a subcutaneous pocket for the medical device and extend from the distal end of the housing, and an inserter configured to form a subcutaneous pocket in tissue of a patient and to move the medical device through the distal opening of the housing, the inserter having a first portion configured to facilitate forming the subcutaneous pocket, and a second portion configured to facilitate moving the medical device through the distal opening of the housing, and, the first portion being configured to disengage from the second portion. 
         [0033]    In Example 30, the system of Example 29, wherein the inserter further comprises a first portion having a first handle portion and a second portion having a second handle portion, wherein the first handle portion is configured to nest within the second handle portion. 
         [0034]    In Example 31, the system of Example 29, wherein the second portion comprises lateral extensions configured to prevent the second portion from disengaging from the housing. 
         [0035]    In Example 32, a method of subcutaneous implanting a medical device using an introducer apparatus comprising a housing having a proximal end, a distal end, and a distal opening defined by the housing, and a tunneler extending from the housing, and an inserter having a first portion and a second portion, the method comprising: making an incision in a patient&#39;s skin; positioning the introducer apparatus within the incision using the tunneler; forming a subcutaneous pocket for the medical device using the first portion of the inserter; removing the first portion of the inserter from the second portion of the inserter; and ejecting the medical device into the subcutaneous pocket through the distal opening of the housing using the second portion of the inserter. 
         [0036]    In Example 33, the method of Example 32, wherein forming the subcutaneous pocket includes using the first portion of the inserter to force apart tissue under the patient&#39;s skin without rotation of the housing or the inserter. 
         [0037]    In Example 34, the method of Example 33, further comprising moving the second portion of the inserter distally relative to the housing prior to ejecting the medical device through the distal opening of the housing via the second portion. 
         [0038]    In Example 35, the method of Example 34, further comprising loading the medical device into a compartment in the housing prior to positioning the introducer apparatus within the incision using the tunneler. 
         [0039]    While multiple embodiments are disclosed, still other embodiments of the present disclosure will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the disclosure. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0040]      FIG. 1  is a perspective view of an illustrative introducer apparatus for a medical device, in accordance with embodiments of the disclosure. 
           [0041]      FIG. 2A  is a cross-sectional perspective view of an illustrative introducer apparatus for a medical device, in accordance with embodiments of the disclosure. 
           [0042]      FIG. 2B  is a cross-sectional perspective view of a proximal portion of a housing and an inserter of the illustrative introducer apparatus, as shown in  FIG. 2B , in accordance with embodiments of the disclosure. 
           [0043]      FIG. 2C  is a cross-sectional perspective end view of the illustrative introducer apparatus, as shown in  FIGS. 2A-B , in accordance with embodiments of the disclosure. 
           [0044]      FIG. 3A  is a perspective view of an illustrative introducer apparatus for a medical device including a removable lock structure, in accordance with embodiments of the disclosure. 
           [0045]      FIG. 3B  is a perspective view of the illustrative introducer apparatus, as shown in  FIG. 3A , with the removable lock structure removed from the introducer apparatus, in accordance with embodiments of the disclosure. 
           [0046]      FIG. 3C  is a perspective view of the illustrative introducer apparatus, as shown in  FIGS. 3A-B , using the inserter to create a subcutaneous pocket, in accordance with embodiments of the disclosure. 
           [0047]      FIG. 3D  is a perspective view of the illustrative introducer apparatus, as shown in  FIGS. 3A-C , having a first portion of the inserter disengaged from a second portion of the inserter, in accordance with embodiments of the disclosure. 
           [0048]      FIG. 3E  is a perspective view of the illustrative introducer apparatus, as shown in  FIGS. 3A-D , having the second portion of the inserter pulled back from the housing prior to moving the medical device into the pocket, in accordance with embodiments of the disclosure. 
           [0049]      FIG. 3F  is a perspective view of the illustrative introducer apparatus, as shown in  FIGS. 3A-E , using the second portion of the inserter to insert the medical device in the pocket, in accordance with embodiments of the disclosure. 
           [0050]      FIG. 3G  is a perspective view of the illustrative introducer apparatus, as shown in  FIGS. 3A-F , with the medical device implanted and the introducer apparatus removed from the pocket, in accordance with embodiments of the disclosure. 
           [0051]    While the disclosed subject matter is amenable to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and are described in detail below. The intention, however, is not to limit the disclosure to the particular embodiments described. On the contrary, the disclosure is intended to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure as defined by the appended claims. 
           [0052]    As the terms are used herein with respect to ranges of measurements (such as those disclosed immediately above), “about” and “approximately” may be used, interchangeably, to refer to a measurement, position, or arrangement, that includes the stated measurement, position, or arrangement and that also includes any measurement, positions, or arrangements that are reasonably close to the stated measurement, position, or arrangement, but that may differ by a reasonably small amount such as will be understood, and readily ascertained, by individuals having ordinary skill in the relevant arts to be attributable to measurement error, differences in measurement and/or manufacturing equipment calibration, human error in reading and/or setting measurements, positions, or arrangements, adjustments made to optimize performance and/or structural parameters in view of differences in measurements, positions, or arrangements associated with other components, particular implementation scenarios, imprecise adjustment and/or manipulation of objects by a person or machine, and/or the like. 
           [0053]    Although the term “block” may be used herein to connote different elements illustratively employed, the term should not be interpreted as implying any requirement of, or particular order among or between, various steps disclosed herein unless and except when explicitly referring to the order of individual steps. Additionally, a “set” or “group” of items (e.g., inputs, algorithms, data values, etc.) may include one or more items, and, similarly, a subset or subgroup of items may include one or more items. 
       
    
    
     DETAILED DESCRIPTION 
       [0054]      FIG. 1  is a perspective view of an illustrative introducer apparatus  100  for a medical device (not shown), in accordance with embodiments of the disclosure. The introducer apparatus  100  includes a housing  102 . The housing  102  may include a compartment or internal area (as discussed in further detail below, for example, with reference to  FIGS. 2A-2C ) that is configured to releasably hold the medical device. The housing  102 , the compartment or internal area, is configured to hold the medical device, and may be formed or manufactured to accommodate medical devices of various sizes. 
         [0055]    As also shown in  FIG. 1 , the introducer apparatus  100  also may also include an inserter  106 . The inserter  106  may be configured to extend through a distal opening defined by the housing (as discussed in further detail below, for example, with reference to  FIGS. 2A-2C  and  FIGS. 3A-F ). In addition, the inserter  106  may be configured to form a subcutaneous pocket in tissue of a patient and move the medical device through the distal opening (from within the housing  102 ). 
         [0056]    Further, the introducer apparatus  100  may also include a tunneler  104  is arranged and extends from the housing  102 . The tunneler  104  may be configured to facilitate formation of the subcutaneous pocket for the medical device. In addition and as shown in  FIG. 1 , a portion  108  of the tunneler  104  may have a greater width than an end portion  110  of the tunneler  104 . The portion  108 , in certain instances, may have a width equal to or approximately equal to a width of the medical device. In addition, the portion  108  may have a width that is 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50% (or any percentage in between) greater than a width of the end portion  110 . In addition, the end portion  110  may comprise a distal tip of the tunneler  104 , which may facilitate movement of the tunneler  104  through the tissue of a patient. The end portion  110  may include a taper such that a depth or thickness of the end portion  110  decreases from the portion  108  toward the end portion  110  of the tunneler  104 . 
         [0057]      FIG. 2A  is a perspective view of an illustrative introducer apparatus  200  for a medical device  202 , in accordance with embodiments of the disclosure. The introducer apparatus  200  includes a housing  211  having a proximal end  212  and a distal end  214 . The housing may also define a proximal opening  216  at or adjacent to the proximal end  212  and a distal opening  218  at or adjacent to the distal end  214 . 
         [0058]    In certain instances, the introducer apparatus  200  may include a tunneler  204  extending from the distal end  214  of the housing  211 . The tunneler  204  may be configured to facilitate forming a subcutaneous pocket for the medical device  202 . In using the introducer apparatus  200 , a user may first make an incision in a patient&#39;s skin. After the incision is made, the introducer apparatus  200  may be positioned within the incision. The medical device  202  may be positioned at a certain depth under the patient&#39;s skin. The tunneler  204  may facilitate pocket formation by tunneling the introducer apparatus  200  into the patient&#39;s tissue. More specifically, the tunneler  204  may include a distal tip  252  having a depth  254  that is less than a depth of remaining section of the tunneler  204 . The depth  254  of the distal tip  252  may facilitate movement of tissue around the tunneler  204  in reaching the depth under the patient&#39;s skin. 
         [0059]    The introducer apparatus  200  may also include an inserter  206 . The inserter may be configured to form the subcutaneous pocket in the tissue and pass the medical device  202  through the distal opening  218  of the housing  211 . As shown in  FIG. 2A , the inserter  206  includes a first portion  208  and a second portion  210  of the inserter  206  that may be cooperatively used to form the subcutaneous pocket. The first portion  208  of the inserter  206  is configured to disengage from the second portion  210  of the inserter  206  to position the medical device within the subcutaneous pocket. In addition, the housing also may include a first channel  220  extending between the proximal opening  216  and the distal opening  218  along a length of the housing  211 . Each of the first portion  208  of the inserter  206  and the second portion  210  of the inserter may be configured to move within the first channel  220  along the length of the housing. 
         [0060]    The introducer apparatus  200  may also include a second channel  222 . As noted above, the first portion  208  of the inserter  206  is configured to disengage from the second portion  210  of the inserter  206 . The first portion  208  of the inserter  206  is also configured to move within the second channel  222 . The second portion  210  of the inserter  206  surrounds the first portion  208  of the inserter  206  when the first portion  208  and the second portion  210  are engaged. In addition, the first portion  208  of the inserter  206  disengages from the second portion  210  of the inserter after the entirety of the first portion  208  of the inserter is moved, within the second channel  222 , proximally relative to the housing  211 . The second channel  222  may be an internal section of the second portion  210  of the inserter  206 . 
         [0061]    The housing  211  may also include a compartment  224  that is configured to releasably hold and contain the medical device  202 . The compartment  224  may be offset relative to or laterally adjacent from the first channel  220 . In addition, the compartment  224  may frictionally engage the medical device  202  to hold the medical device  202  within the compartment  224 . In addition, the compartment  224  may include a snap-feature  226  that facilitates holding the medical device  202  within the compartment  224 . The snap-feature  226  may be formed of a portion of the housing  211  that is moveable with respect to remaining portions of the housing  211 . As a result, the snap-feature  226  may be configured to bend or tilt outwardly away from the compartment  224  and the first channel  220  by a user. The user may bend or tilt the snap-feature  226  away from the compartment  224  and the first channel  220  in order to load the medical device  202  in the compartment  224 , and release the snap-feature  226  to secure the medical device  202  therein. 
         [0062]    The medical device  202  may be released from the compartment  224  in response to the first portion  208  being moved proximally relative to the housing  211 . Moving the first portion  208  of the inserter  206  proximally relative to the housing  211  may leave behind a space in the first channel  220 , previously occupied by the first portion  208 , and the medical device  202  may be released from the compartment  224  into the first channel  220 . Subsequent movement of the first portion  208  and/or the second portion  210  of the inserter  206  distally relative to the housing  211  along the first channel  220  will also move the medical device  202  along the first channel  220 . As a result, the medical device  202  may be deployed or ejected from the distal opening of  218  of the housing  211 . 
         [0063]      FIG. 2B  is a cross-sectional perspective view of a proximal portion of the housing  211  and the inserter  206  of the illustrative introducer apparatus  200  as shown in  FIG. 2B , in accordance with embodiments of the disclosure. As shown in  FIG. 2B , the first portion  208  of the inserter  206  may include a first handle portion  228 , and the second portion  210  of the inserter  206  may include a second handle portion  230 . The handle portions  228 ,  230  provide a gripping surface for a user to, respectively, facilitate moving the first portion  208  and the second portion  210  of the inserter  206 . 
         [0064]    In certain instances, the handle portion  228  of the first portion  208  of the inserter  206  is configured to nest within the handle portion  230  of the second portion  210  of the inserter  206 . More specifically and in certain instances, the first handle portion  228  may include a first lower surface  244  and a first upper surface  246 . In addition, the second handle portion  230  may include a second upper surface  248  and a second lower surface  250 . The first lower surface  244  and the second upper surface  248  are corresponding surfaces. The first lower surface  244  and the second upper surface  248  may take any shape so long as the first lower surface  244  and the second upper surface  248  mirror one another. For instance and as shown in  FIG. 2B , the first lower surface  244  is convex, and the corresponding second upper surface  248  is concave. 
         [0065]    Similar to the first portion  208  and the second portion  210  of the inserter  206 , the housing  211  may also include handle portions  232 ,  234  arranged at the proximal end  212 . The handle portions  232 ,  234  facilitate a user&#39;s ability to grip and move the housing  211  and the introducer apparatus  200 . 
         [0066]    As noted above, the first portion  208  of the inserter  206  is configured to disengage from the second portion  210  of the inserter  206 . In certain instances, the second portion  210  of the inserter  206  may be coupled to the housing  211 . Further, the second portion  210  of the inserter  206  may include lateral extensions  236 ,  238  that interface with the housing  211 . The lateral extensions  236 ,  238  may prevent the second portion  210  of the inserter  206  from being separated or disengaged from the housing  211 . More specifically, the lateral extensions  236 ,  238  have a greater width than a width of the proximal opening  216 . In addition, the width of the lateral extensions  236 ,  238  may be sized to move along the first channel  220 . 
         [0067]    In certain instances, the introducer apparatus  200  may include a lock structure  240  that is removable from the housing  211 . The lock structure  240  is configured to hold the first portion  208  and the second portion  210  of the inserter  206  relative to the housing  211  in an initial configuration. The lock structure  240  may also include a first protrusion  242  and/or a second protrusion  256  that interface with and frictionally engage a portion of the housing  211 . As a result, the lock structure  240  is held in place until a user applies force to remove the lock structure  240  from the housing  211 . In addition, each of the first portion  208  of the inserter  206  and the second portion  210  of the inserter  206  may be configured to move within the first channel  220  along the length of the housing after removal of the lock structure  240 . 
         [0068]      FIG. 2C  is a cross-sectional perspective end view of the illustrative introducer apparatus  200 , as shown in  FIGS. 2A-B , in accordance with embodiments of the disclosure. As shown in  FIG. 2C , the compartment  224  is laterally offset from the first channel  220 . The snap-feature  226  is shown as a separate portion of the housing  211 , which impinges the compartment  224  in an initial configuration (shown in  FIG. 2C ). As described above with reference to  FIG. 2A , the snap-feature  226  may be configured to bend or tilt outwardly away from the compartment  224 . The user may bend or tilt the snap-feature  226  away from the compartment  224  in order to load the medical device  202  (not shown in  FIG. 2C ) in the compartment  224 , and release the snap-feature  226  to secure the medical device  202  therein. Release of the snap-feature  226  may make an audible sound (such as a click) as the result of the snap-feature  226  contacting the medical device  202  and/or the housing  211 . 
         [0069]      FIG. 2C  also shows the first portion  208  and the second portion  210  of the inserter  206 . As shown therein. The second portion  210  surrounds the first portion  208 , and both the first portion  208  and the second portion  210  are contained within the first channel  220 . As a result, a width of the first portion  208  may be smaller than a width of the second portion  210 . The second channel  222  is occupied by the first portion  208  of the inserter in the configuration shown in  FIG. 2C . As shown in  FIG. 2C , the second portion  210  may include a “U” shape that is configured to form the second channel  222  and move/pass the first portion  208  of the inserter  206  therethrough. 
         [0070]    Each of  FIGS. 3A-G  may be illustrative of steps in a method of subcutaneous implanting a medical device using an introducer apparatus. The illustrative components shown in  FIGS. 3A-G  are not intended to suggest any limitation as to the scope of use or functionality of embodiments of the disclosed subject matter. Neither should the illustrative components be interpreted as having any dependency or requirement related to any single component or combination of components illustrated therein. As a result, the illustrative introducer apparatus shown in  FIGS. 3A-G , and the components associated therewith, may be, in embodiments, integrated with various other components depicted therein (and/or components not illustrated), all of which are considered to be within the ambit of the disclosed subject matter. For example, the illustrative introducer apparatuses depicted in  FIG. 1  and  FIG. 2A-C  may be used as the introducer apparatus in a method of subcutaneous implanting a medical device. 
         [0071]      FIG. 3A  is a perspective view of an illustrative introducer apparatus  300  for a medical device (shown in  FIGS. 3F-G ) including a removable lock structure  320 , in accordance with embodiments of the disclosure. The introducer apparatus  300  includes a housing  302 . The housing  302  may include a compartment  322  that is configured to releasably hold the medical device. The compartment  322  may include a snap-feature  324  that facilitates holding the medical device within the compartment  322 . The medical device may be loaded into the compartment  322  in this configuration. In certain instances, the medical device may also be loaded into the compartment  322  at any point prior to ejecting the device from the housing  302 . In addition, the housing  302  has a proximal end  306  and a distal end  308 . Further, the housing  302  may define a proximal opening  310  (shown in  FIG. 3B ) and a distal opening  312  (shown in  FIGS. 3E-F ). The housing  302 , the compartment  322 , and each of the proximal opening  310  and distal opening  312  may be formed or manufactured to accommodate medical devices of various sizes. 
         [0072]    The introducer apparatus  300  may also include a tunneler  304  arranged at and extending from the distal end  308  of the housing  302 . The tunneler  304  is configured to facilitate forming a subcutaneous pocket for the medical device. The introducer apparatus  300  may also include an inserter  314  configured to pass the medical device through the distal opening  312  of the housing  302 . The inserter  314  may include a first portion  316  and a second portion  318  that are cooperatively used to form the subcutaneous pocket. As discussed in further detail below, the first portion  316  is configured to disengage from the second portion  318 , and the second portion  318  to position the medical device within the subcutaneous pocket. 
         [0073]    In certain instances, the introducer apparatus  300  may include a removable lock structure  320  configured to hold the first portion  316  and the second portion  318  relative to the housing  302  in an initial configuration (as shown in  FIG. 3A ). A user will remove the removable lock structure  320  from the housing  302  in order to move the first portion  316  and the second portion  318 . 
         [0074]    As shown in  FIG. 3A , the introducer apparatus  300  is shown positioned within an incision  326 . The tunneler  304  is also positioned within the incision  326 . After the incision is made, the tunneler  304  may facilitate pocket formation by tunneling the introducer apparatus  300  into the patient&#39;s tissue through the incision. The medical device may be positioned at a certain depth under the patient&#39;s skin. As a result, the tunneler  304  facilitates movement of tissue around the tunneler  304  in reaching the depth under the patient&#39;s skin. In certain instances, the tunneler  304  is positioned within the incision  326  such that the distal opening  312  of the housing  302  abuts the incision  326 . 
         [0075]      FIG. 3B  is a perspective view of the illustrative introducer apparatus, as shown in  FIG. 3A , with the removable lock structure  320  removed from the introducer apparatus  300 , in accordance with embodiments of the disclosure. In order to move the removable lock structure  320 , a user may twist or rotate the removable lock structure  320  relative to the housing  302  to disengage the removable lock structure  320 . After the removable lock structure  320  is removed from the introducer apparatus  300 , the inserter  314  may move relative to the housing  302 . 
         [0076]      FIG. 3C  is a perspective view of the illustrative introducer apparatus  300 , as shown in  FIGS. 3A-B , using the inserter  314  to create a subcutaneous pocket, in accordance with embodiments of the disclosure. The inserter  314  is moved proximally relative to the housing  302  (from the configuration shown in  FIG. 3B ) to create the subcutaneous pocket. In certain instances, the first portion  316  is configured to create the subcutaneous pocket. The first portion  316  may include a proximal end  328  (shown in further detail in  FIG. 3D ) and a distal end  330 . The first portion  316  also may include a first extension portion  332 . As discussed in further detail below with reference to  FIGS. 3E-F , the second portion  318  includes a second extension portion  340  (shown in  FIG. 3E ). Each of the first extension portion  332  and the second extension portion  340  (shown in  FIG. 3E ) are configured to extend through the distal opening  312  (shown in  FIGS. 3E-F ) of the housing  302  in a fully-extended configuration of the first portion  316  and the second portion  318 . As shown in  FIG. 3C , a distal end  330  of the first extension portion  332  extends through the housing  302 , and a distal end  338  of the second extension portion (shown in  FIGS. 3E-F ) the distal opening  312 . 
         [0077]    In certain instances, extending the first portion  316  of the inserter  314  through the distal opening  312  of the housing  302  (and into the patient&#39;s skin) forms a subcutaneous pocket for the medical device. Forcing the first portion  316  of the inserter  314  through tissue beneath the incision  326  opens space thereby creating the pocket for implanting the medical device. In embodiments, the first portion  316  forces apart tissue under the patient&#39;s skin without rotation of the housing  302  or the inserter  314 . 
         [0078]      FIG. 3D  is a perspective view of the illustrative introducer apparatus  300 , as shown in  FIGS. 3A-C , having the first portion  316  of the inserter  314  disengaged from the second portion  318  of the inserter  314 , in accordance with embodiments of the disclosure. After the first portion  316  of the inserter  314  has created the pocket, the first portion  316  of the inserter  314  maybe withdrawn proximally relative to the housing  302 . As shown in  FIG. 3D , the first portion  316  of the inserter  314  is configured to disengage from the housing  302 . The second portion  318  of the inserter  314  may remain extended through the housing  302  during removal of the first portion  316 . The second portion  318  may hold the medical device  346  positioned within the subcutaneous pocket during removal of the first portion  316 . As a result, the medical device  346  will not eject from the subcutaneous pocket due to the removal of the first portion  316  because the second portion  318  holds the medical device  346  in place. Thus, the first portion  316  and the second portion  318  may be configured to form the subcutaneous pocket without rotation of the housing or the inserter. As shown in  FIG. 3D , the distal end  338  remains body within the incision  326 . 
         [0079]      FIG. 3E  is a perspective view of the illustrative introducer apparatus  300 , as shown in  FIGS. 3A-D , having the second portion  318  of the inserter pulled back from the housing  302  prior to moving the medical device into the pocket, in accordance with embodiments of the disclosure. After the first portion  316  of the inserter  314  has created the pocket and been disengaged from the second portion  318  of the inserter  314 , the second portion  318  may be moved proximally relative to the housing  302 . As described with reference to  FIGS. 2A-B , moving the second portion  318  in this step may position the medical device for implantation. The medical device may release from the compartment  322  into the pathway of the second portion  318  of the inserter  314 . The medical device is transitioned into a loading configuration by removing the first portion  316  of the inserter  314  and moving the second portion  318  proximally into a loading configuration (shown in  FIG. 3E ). 
         [0080]    Structural differences between the first portion  316  and the second portion  318  may be seen in comparing  FIG. 3D  and  FIG. 3E . For instance, the first portion  316  of the inserter  314  may include a proximal end  328  and the distal end  330 , a first handle portion  334  arranged at the proximal end  328  of the first portion  316 . The first extension portion  332  extends from the first handle portion  334 . In addition, the second portion  318  may include a proximal end  336  and the distal end  338 , and a second handle portion  342  arranged at the proximal end  336  of the second portion  318 . The second portion  318  may also include a second extension portion  340  extending from the second handle portion  342 . In addition, the second portion  318  may include a second channel  344  along a length of the second extension portion  340 . 
         [0081]    As shown in comparing  FIG. 3D  and  FIG. 3E , the first extension portion  332  has a first length and the second extension portion  340  has a second length, with the first length being greater than the second length. The differences in length between the first extension portion  332  and the second extension portion  340  is also shown in  FIG. 3C  with the distal end  330  of the first extension portion  332  extending further into the patient than the distal end  338  of the second extension portion  340 . 
         [0082]      FIG. 3F  is a perspective view of the illustrative introducer apparatus  300 , as shown in  FIGS. 3A-E , using the second portion  318  of the inserter  314  to insert the medical device  346  in the pocket, in accordance with embodiments of the disclosure. As shown in  FIG. 3F , the second portion  318  of the inserter  314  is moved distally relative to the housing  302  to eject the medical device  346  through the distal opening  312  of the housing  302  via the second portion  318 . The second portion  318  of the inserter  314  is shown in a fully-extended configuration with the first portion  316  being disengaged from the second portion  318 . In addition, the second extension portion  340  may be configured to extend through the distal opening  312  of the housing  302  in the fully-extended configuration. As is shown in  FIG. 3F , the distal end  338  of the second portion  318  extends through the housing  302  to eject the medical device  346  therefrom.  FIG. 3G  is a perspective view of the illustrative introducer apparatus  300 , as shown in  FIGS. 3A-F , with the medical device  346  implanted and the introducer apparatus  300  removed from the pocket, in accordance with embodiments of the disclosure. 
         [0083]    The illustrative components shown in  FIGS. 3A-G  are not intended to suggest any limitation as to the scope of use or functionality of embodiments of the disclosed subject matter. Neither should the illustrative components be interpreted as having any dependency or requirement related to any single component or combination of components illustrated therein. Additionally, any one or more of the components depicted in  FIGS. 3A-G  may be, in embodiments, integrated with various other components depicted therein (and/or components not illustrated), all of which are considered to be within the ambit of the disclosed subject matter. For example, first portion  316  may include a first channel extending between the proximal opening  310  and the distal opening  312  along a length of the housing  302  (e.g., as discussed above with reference to  FIGS. 2A-C ). 
         [0084]    In certain instances, any of the illustrative introducer apparatuses described herein and an implantable medical device may be provided as a system. In addition to the introducer apparatus and the implantable medical device, the system may also include a device for making an incision in a patient. This device for making the incision (not shown) may be any device having a sharp edge (such as scalpel). In addition, the incision may be made using a plunge cutter, or, for example, a vibratory plunge cutter as discussed in U.S. Provisional Patent No. 62/159,510, Titled “Vibratory Plunge Cutter,” and herein incorporated by reference. 
         [0085]    Various modifications and additions can be made to the illustrative embodiments discussed without departing from the scope of the present disclosure. For example, while the embodiments described above refer to particular features, the scope of this disclosure also includes embodiments having different combinations of features and embodiments that do not include all of the described features. Accordingly, the scope of the present disclosure is intended to embrace all such alternatives, modifications, and variations as fall within the scope of the claims, together with all equivalents thereof.