Abstract:
An apparatus for guiding the placement of a subcutaneous device that includes a strap having an indentation configured for a fold of skin and fat layer to be positioned within the indentation as the subcutaneous device is advanced to a desired implantation site.

Description:
RELATED APPLICATION  
       [0001]    This application claims the benefit of and priority to U.S. Provisional Application Ser. No. 61/190,052, filed Jul. 31, 2008, entitled, “Apparatus for Guiding The Placement of a Subcutaneous Device” and to U.S. Provisional Application Ser. No. 61/116,492, filed Nov. 20, 2008, entitled, “Apparatus for Guiding The Placement of a Subcutaneous Device” the contents of which are incorporated by reference herein in its entirety. 
       CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0002]    Cross-reference is hereby made to the commonly assigned related U.S. Applications, Attorney Docket Number P0033646.00, entitled “MEDICAL DEVICE SYSTEM AND APPARATUS FOR GUIDING THE PLACEMENT OF A SUBCUTANEOUS DEVICE”, to Havel et al.; and Attorney Docket Number P0035525.00, entitled “MEDICAL DEVICE SYSTEM AND APPARATUS FOR GUIDING THE PLACEMENT OF A SUBCUTANEOUS DEVICE”, to Havel et al.; and Attorney Docket Number P0035526.00, “MEDICAL DEVICE SYSTEM AND APPARATUS FOR GUIDING THE PLACEMENT OF A SUBCUTANEOUS DEVICE”, to Havel et al., filed concurrently herewith and incorporated herein by reference in their entireties. 
     
    
     BACKGROUND OF THE INVENTION  
       [0003]    A subcutaneous device, such as a coil electrode for an implantable cardioverter-defibrillator (ICD), is typically implanted in a patient while the patient is lying supine on his or her back. The subcutaneous device is implanted using a tunneling tool that provides enough stiffness and pushability to create a space between the subcutaneous and muscular plane. With the patient on his or her back, it is difficult for a physician to maneuver a tunneling tool around the curvature of the posterior axilla to continue tunneling from the axilla to the spine. 
         [0004]    There are two major potential problems that a physician may encounter while implanting a subcutaneous device using a tunneling tool. The first problem includes the tunneling tool turning inward between the ribs and into muscle and potentially creating a pneumothorax. The second problem includes the tunneling tool turning outward and potentially puncturing the skin. Some physicians will have a non-sterile scrub nurse put a hand under the patient&#39;s back to help guide the tunneling tool and to give the skin support so the tunneling tool does not penetrate the skin. Other physicians will use x-ray or other suitable imaging systems to help guide the tunneling tool. 
         [0005]    For these and other reasons, there is a need for the present invention. 
       SUMMARY OF THE INVENTION  
       [0006]    One embodiment provides an apparatus for guiding the placement of a subcutaneous device. The apparatus includes a strap comprising an indentation configured for a fold of skin and fat layer to be positioned within the indentation. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0007]      FIG. 1A  illustrates a cross-sectional view of one embodiment of an apparatus for guiding the placement of a subcutaneous device. 
           [0008]      FIG. 1B  illustrates a perspective view of one embodiment of an apparatus for guiding the placement of a subcutaneous device. 
           [0009]      FIG. 2  illustrates a cross-sectional view of another embodiment of an apparatus for guiding the placement of a subcutaneous device. 
           [0010]      FIG. 3  illustrates a perspective view of another embodiment of an apparatus for guiding the placement of a subcutaneous device. 
           [0011]      FIG. 4  is a diagram illustrating one embodiment of an apparatus attached to a patient for guiding the placement of a subcutaneous device. 
           [0012]      FIG. 5  is a diagram illustrating one embodiment of a tunneling tool. 
           [0013]      FIG. 6A  is a diagram illustrating one embodiment of using the tunneling tool and the apparatus for guiding the placement of a subcutaneous device in a patient. 
           [0014]      FIG. 6B  is a diagram illustrating another embodiment of using the tunneling tool and an apparatus for guiding the placement of a subcutaneous device in a patient. 
           [0015]      FIG. 6C  is a diagram illustrating another embodiment of using the tunneling tool and an apparatus for guiding the placement of a subcutaneous device in a patient. 
           [0016]      FIG. 7  illustrates a cross-sectional view of one embodiment of using the tunneling tool and the apparatus for guiding the placement of a subcutaneous device in a patient. 
           [0017]      FIG. 8  illustrates a cross-sectional view of another embodiment of using the tunneling tool and an apparatus including a vacuum system for guiding the placement of a subcutaneous device in a patient. 
           [0018]      FIG. 9  illustrates a cross-sectional view of another embodiment of an apparatus for guiding the placement of a subcutaneous device. 
           [0019]      FIG. 10  illustrates a cross-sectional view of another embodiment of an apparatus for guiding the placement of a subcutaneous device. 
           [0020]      FIG. 11  illustrates a cross-sectional view of another embodiment of using the tunneling tool and the apparatus for guiding the placement of a subcutaneous device in a patient. 
           [0021]      FIG. 12  illustrates a cross-sectional view of another embodiment of using the tunneling tool and the apparatus for guiding the placement of a subcutaneous device in a patient. 
           [0022]      FIG. 13  illustrates a cross-sectional view of another embodiment of using the tunneling tool and the apparatus for guiding the placement of a subcutaneous device in a patient. 
           [0023]      FIG. 14  illustrates a bottom view of another embodiment of an apparatus for guiding the placement of a subcutaneous device. 
           [0024]      FIG. 15  illustrates a cross-sectional view of another embodiment of using the tunneling tool and the apparatus for guiding the placement of a subcutaneous device in a patient. 
           [0025]      FIG. 16  illustrates a cross-sectional view of another embodiment of using the tunneling tool and the apparatus for guiding the placement of a subcutaneous device in a patient. 
           [0026]      FIG. 17  illustrates a cross-sectional view of another embodiment of using the tunneling tool and the apparatus for guiding the placement of a subcutaneous device in a patient. 
           [0027]      FIG. 18  illustrates a cross-sectional view of another embodiment of an apparatus for guiding the placement of a subcutaneous device. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0028]      FIGS. 1A  illustrates a cross-sectional view of one embodiment of an apparatus  100  for guiding the placement of a subcutaneous device.  FIG. 1B  illustrates a perspective view of apparatus  100 . Apparatus  100  includes a strap  102  including an indentation  104  formed along the length of strap  102 . Indentation  104  includes a base portion  106 , a first sidewall portion  108 , and a second sidewall portion  110 . Second sidewall portion  110  is opposite first sidewall portion  108 . 
         [0029]    Apparatus  100  is positioned over the appropriate intercostal space from the mid-axilliary line to the spine of a patient. Apparatus  100  is then attached to the patient. Indentation  104  allows a fold of skin and fat layer of the patient to compress into indentation  104  or to be positioned within indentation  104  when the patient lies down on an operating table. Indentation  104  provides a mechanical guide for a tunneling tool during the placement of a subcutaneous device, such as a coil electrode or lead. Indentation  104  also provides for more precise placement of the subcutaneous device compared to typical methods. In addition, apparatus  100  holds the skin taut so that the skin does not fold or snag during tunneling. Apparatus  100  replaces the need to have a hand over the top of the patient&#39;s skin or the need to use x-ray or other imaging systems to assist the physician in guiding the tunneling tool. 
         [0030]    Strap  102  is made of a semi-stiff material such that strap  102  conforms to a patient&#39;s body yet is sufficiently rigid to enable a fold of skin and fat layer of the patient to be compressed into indentation  104  with strap  102  attached to the patient. In one embodiment, strap  102  is made of plastic that has sufficient flex to conform to a patient&#39;s body. In another embodiment, strap  102  is made of rubber. In other embodiments, strap  102  is made of other suitable materials or combinations of materials. In one embodiment, strap  102  is approximately 12 to 18 inches long. In one embodiment, strap  102  can be sterilized. 
         [0031]      FIG. 2  illustrates a cross-sectional view of another embodiment of an apparatus  110  for guiding the placement of a subcutaneous device. Apparatus  110  is similar to apparatus  100  previously described and illustrated with reference to  FIGS. 1A and 1B , except that apparatus  110  includes adhesive  112 . Adhesive  112  is attached to the bottom  114  of strap  102  adjacent to indentation  104 . Adhesive  112  is used to attach strap  102  to a patient. In one embodiment, adhesive  112  includes a double sided tape. In other embodiments, adhesive  112  is applied to strap  102 , which is then attached to a patient. 
         [0032]      FIG. 3  illustrates a perspective view of another embodiment of an apparatus  120  for guiding the placement of a subcutaneous device. Apparatus  120  is similar to apparatus  100  previously described and illustrated with reference to  FIGS. 1A and 1B , except that apparatus  120  includes bands  122 . Bands  122  are attached to strap  102  adjacent to indentation  104 . Bands  122  are used to attach strap  102  to a patient by wrapping bands  122  around the patient. In one embodiment, bands  122  are elasticized bands or other suitable bands suitable for attaching strap  102  to a patient. 
         [0033]      FIG. 4  is a diagram illustrating one embodiment of an apparatus  132  attached to a patient  130  for guiding the placement of a subcutaneous device. Apparatus  132  includes a strap  134  including an indentation similar to apparatus  100  previously described and illustrated with reference to  FIGS. 1A and 1B , apparatus  110  previously described and illustrated with reference to  FIG. 2 , or apparatus  120  previously described and illustrated with reference to  FIG. 3 . 
         [0034]    In one embodiment, strap  134  is attached to patient  130  such that end  136  of strap  134  is at the desired location for the placement of a subcutaneous device. In one embodiment, strap  134  includes a mark or marks  138  for indicating how far a tunneling tool should be inserted to reach the desired location for the placement of a subcutaneous device at end  136  of strap  134 . The distance between end  136  of strap  134  and mark or marks  138  is indicated at  140 . 
         [0035]      FIG. 5  is a diagram illustrating one embodiment of a tunneling tool  150 . Tunneling tool  150  includes a handle  152  at a proximal end and a tip  156  at a distal end. In one embodiment, tunneling tool  150  includes a mark or marks  154  at the proximal end near handle  152 . Mark or marks  154  correspond to mark or marks  138  on strap  134  previously described and illustrated with reference to  FIG. 4 . The distance between mark or marks  154  and tip  156  of tunneling tool  150  indicated at  158  equals the distance between mark or marks  138  and end  136  of strap  134  indicated at  140 . Therefore, by aligning mark or marks  154  on tunneling tool  150  with mark or marks  138  on strap  134 , tip  156  of tunneling tool  150  is positioned at end  136  of strap  134  for placing a subcutaneous device at the desired location. 
         [0036]      FIG. 6A  is a diagram illustrating one embodiment of using tunneling tool  150  and apparatus  132  for guiding the placement of a subcutaneous device in a patient  130 . Apparatus  132  is attached to patient  130  and the patient lies down on an operating table. A physician makes a subcutaneous pocket incision at  160  and inserts tunneling tool  150  into incision  160 . As the physician advances tunneling tool  150  using apparatus  132  as a mechanical guide for the tunneling tool, the tunneling tool creates a space between the subcutaneous and muscular plane in patient  130 . The physician continues to advance tunneling tool  150  until mark or marks  154  on tunneling tool  150  are aligned with mark or marks  138  on strap  134  indicating that tip  156  of tunneling tool  150  is at the desired location for placing the subcutaneous device. 
         [0037]      FIG. 6B  is a diagram illustrating another embodiment of using tunneling tool  150  and an apparatus  142  for guiding the placement of a subcutaneous device in a patient  130 . In this embodiment, apparatus  142  includes a handle  144 , which is attached to the proximal end of the strap via an open frame connection  143 . The open frame connection  143  between handle  144  and the strap provides a window through which a physician can access incision  160  and insert tunneling tool  150 . As the physician inserts tunneling tool  150  by applying a force on handle  152  as indicated by arrow  145 , a counterforce as indicated by arrow  146  is applied to handle  144  such that apparatus  142  keeps the skin of patient  130  taut to make advancement of tunneling tool  150  easier. 
         [0038]      FIG. 6C  is a diagram illustrating another embodiment of using tunneling tool  150  and an apparatus  147  for guiding the placement of a subcutaneous device in a patient  130 . In this embodiment, apparatus  147  includes a handle  148 , which is directly attached to the proximal end of the strap. In one embodiment, handle  148  is attached to the strap at a 90 degree angle or another suitable angle such that handle  148  does not interfere with handle  152  of tunneling tool  150 . As the physician inserts tunneling tool  150  by applying a force on handle  152  as indicated by arrow  145 , a counterforce as indicated by arrow  146  is applied to handle  148  such that apparatus  147  keeps the skin of patient  130  taut to make advancement of tunneling tool  150  easier. 
         [0039]      FIG. 7  illustrates a cross-sectional view of one embodiment of using tunneling tool  150  and apparatus  132  for guiding the placement of a subcutaneous device in a patient  130 . A skin and fat layer or cutaneous tissue  172  of patient  130  is compressed into indentation  104  of strap  134 . By using strap  134  as a mechanical guide, tunneling tool  150  creates a space between the skin and fat layer  172  and muscle  174 . 
         [0040]      FIG. 8  illustrates a cross-sectional view of another embodiment of using tunneling tool  150  and an apparatus  180  including a vacuum system  184  for guiding the placement of a subcutaneous device in a patient  130 . A vacuum system  184  is attached to apparatus  180  through a vacuum line  186 . Vacuum line  186  passes through strap  182  to indentation  104 . The vacuum pulls the skin upward to be positioned within indentation  104  and holds skin and fat layer  172  in indentation  104 . In one embodiment, the vacuum is provided within indentation  104  along the entire length of strap  182  using a network of vacuum lines within strap  182 . In one embodiment, the ends of strap  182  are sealed to prevent air outside of strap  182  from entering vacuum system  184 . 
         [0041]      FIG. 9  illustrates a cross-sectional view of another embodiment of an apparatus  200  for guiding the placement of a subcutaneous device. Apparatus  200  is similar to apparatus  100  previously described and illustrated with reference to  FIGS. 1A and 1B , except that apparatus  200  includes additional material  202 . In one embodiment, the top and sidewalls of strap  102  are coated with a polymer  202  or other suitable material. Material  202  is selected such that apparatus  200  is smooth to the touch and is slippery to allow a patient to move on an operating table without binding or sticking to the table surface. 
         [0042]    In one embodiment, a hollow channel or channels  204  are provided along the length of strap  102  through material  202 . In another embodiment, channels  204  are provided through strap  102 . After apparatus  200  is attached to a patient, a tunneling tool can be inserted into a channel  204  to shape the tunneling tool to conform to the patient&#39;s body prior to inserting the tunneling tool into the patient&#39;s body. 
         [0043]      FIG. 10  illustrates a cross-sectional view of another embodiment of an apparatus  210  for guiding the placement of a subcutaneous device. Apparatus  210  is similar to apparatus  100  previously described and illustrated with reference to  FIGS. 1A and 1B , except that apparatus  210  includes a conductive surface  212  along the base portion  106  of indentation  104 . Conductive surface  212  provides an indifferent conductor or electrode for an impedance measurement between electrode  212  and the tip of a lead or the tip of a tunneling tool, which provides the active probe for the impedance measurement. In one embodiment, the impedance measurement provides an electrical guide for guiding the tunneling tool during placement of a subcutaneous device. The impedance measurement provides an indication of the depth of the tunneling tool beneath the skin. As the tunneling tool moves toward a patient&#39;s skin, the impedance decreases. As the tunneling move toward a patient&#39;s muscle, the impedance increases. 
         [0044]      FIG. 11  illustrates a cross-sectional view of another embodiment of using a tunneling tool  220  and apparatus  210  for guiding the placement of a subcutaneous device in a patient  130 . Apparatus  210  including electrode  212  is attached to a patient  130 . In one embodiment, a conductive gel or other suitable material is applied to electrode  212  before attaching apparatus  210  to the patient. Electrode  212  is electrically coupled to one side of an ammeter  226  through signal path  224 . The other side of ammeter  226  is electrically coupled to one side of a voltage source  230  through signal path  228 . The other side of voltage source  230  is electrically coupled to a tunneling tool electrode  222  through signal path  232 . In one embodiment, tunneling tool electrode  222  is the tip of a lead. In another embodiment, tunneling tool electrode  222  is the tip of tunneling tool  220 . Signal path  232  passes through the inside of tunneling tool  220  to the tunneling tool electrode  222 . Except for the tunneling tool electrode  222 , tunneling tool  220  is electrically insulated. 
         [0045]    Voltage source  230  provides a voltage between electrode  212  and tunneling tool electrode  222 . Ammeter  226  measures the current between electrode  212  and tunneling tool electrode  222 . As the impedance between electrode  212  and tunneling tool electrode  222  increases, the current indicated by ammeter  226  between electrode  212  and tunneling tool electrode  222  decreases. As the impedance between electrode  212  and tunneling tool electrode  222  decreases, the current indicated by ammeter  226  between electrode  212  and tunneling tool electrode  222  increases. Therefore, by monitoring the current indicated by ammeter  226 , the depth of tunneling tool  220  beneath the patient&#39;s skin can be determined. In this embodiment, tunneling tool  220  is in the desired space between cutaneous tissue  172  and muscle  174 . As such, the needle of ammeter  226  is centered indicating that tunneling tool  220  is in the desired space. In other embodiments, ammeter  226  is replaced with a digital meter or other suitable monitor for indicating the impedance between electrode  212  and tunneling tool electrode  222 . 
         [0046]      FIG. 12  illustrates a cross-sectional view of another embodiment of using tunneling tool  220  and apparatus  210  for guiding the placement of a subcutaneous device in a patient  130 . In this embodiment, tunneling tool  220  includes a bend at  240  that is pushing tunneling tool electrode  222  into cutaneous tissue  172  toward the patient&#39;s skin. As such, the needle of ammeter  226  is to the right indicating a lower impedance since tunneling tool  220  is approaching the patient&#39;s skin. The indication of impedance provided by ammeter  226  can be used to correct the position of tunneling tool  220  before tunneling tool  220  punctures the patient&#39;s skin. 
         [0047]      FIG. 13  illustrates a cross-sectional view of another embodiment of using tunneling tool  220  and apparatus  210  for guiding the placement of a subcutaneous device in a patient  130 . In this embodiment, tunneling tool  220  includes a bend at  242  that is pushing tunneling tool electrode  222  into muscle  174 . As such, the needle of ammeter  226  is to the left indicating a higher impedance since tunneling tool  220  is in the patient&#39;s muscle  174 . The indication of impedance provided by ammeter  226  can be used to correct the position of tunneling tool  220  before tunneling tool  220  creates a pneumothorax. 
         [0048]      FIG. 14  illustrates a bottom view of another embodiment of an apparatus  250  for guiding the placement of a subcutaneous device. Apparatus  250  includes a strap  252  including a reference electrode  256  and a bipole electrode  254 . Reference electrode  256  is similar to electrode  212  previously described and illustrated with reference to  FIG. 10 , except that reference electrode  256  does not extend the entire length of strap  252 . Reference electrode  256  is used similarly to electrode  212 . Bipole electrode  254  is used as a target for positioning the tip of a tunneling tool for the placement of a subcutaneous device. 
         [0049]      FIG. 15  illustrates a cross-sectional view of another embodiment of using tunneling tool  220  and apparatus  250  for guiding the placement of a subcutaneous device in a patient  130 . Apparatus  250  including reference electrode  256  and bipole electrode  254  is attached to a patient  130 . Apparatus  250  is attached to patient  130  such that bipole electrode  254  is positioned above the desired location for the placement of a subcutaneous device. Reference electrode  256  is electrically coupled to the negative terminal of voltage source  230  through signal path  262 . The positive terminal of voltage source  230  is electrically coupled to tunneling tool electrode  222  through signal path  264 . Bipole electrode  254  is electrically coupled to a voltmeter  260 . 
         [0050]    Voltage source  230  provide a voltage between reference electrode  256  and tunneling tool electrode  222 . Bipole electrode  254  provides a target location for a subcutaneous device. Voltmeter  260  indicates the position of tunneling tool electrode  222  based on the polarity indicated by the needle of voltmeter  260 . In this embodiment, tunneling tool  220  has not yet reached the target location. As such, the needle of voltmeter  260  is to the right indicating a positive polarity. Therefore, the physician should continue to advance tunneling tool  220  toward the target location. 
         [0051]      FIG. 16  illustrates a cross-sectional view of another embodiment of using tunneling tool  220  and apparatus  250  for guiding the placement of a subcutaneous device in a patient  130 . In this embodiment, tunneling tool  220  has reached the target location. As such, the needle of voltmeter  260  is zeroed. Therefore, the physician should stop advancing tunneling tool  220  and place the subcutaneous device at the target location. 
         [0052]      FIG. 17  illustrates a cross-sectional view of another embodiment of using tunneling tool  220  and apparatus  250  for guiding the placement of a subcutaneous device in a patient  130 . In this embodiment, tunneling tool  220  has past the target location. As such, the needle of voltmeter  260  is to the left indicating a negative polarity. Therefore, the physician should stop advancing tunneling tool  220  and begin retreating tunneling tool  220  toward the target location. 
         [0053]      FIG. 18  illustrates a cross-sectional view of another embodiment of an apparatus  270  for guiding the placement of a subcutaneous device. Apparatus  270  is similar to apparatus  210  previously described and illustrated with reference to  FIG. 10 , except that apparatus  270  includes a first conductive surface  272  along first sidewall portion  108  of indentation  104  and a second conductive surface  274  along second sidewall portion  110  of indentation  104 . Conductive surface  272  provides a first indifferent conductor or first electrode for a first impedance measurement between first electrode  272  and the tip of a lead or the tip of a tunneling tool, which provides the active probe for the impedance measurement. Conductive surface  274  provides a second indifferent conductor or second electrode for a second impedance measurement between second electrode  274  and the tip of a lead or the tip of a tunneling tool. 
         [0054]    In one embodiment, the first and second impedance measurements provide an electrical guide for assisting a physician in guiding the tunneling tool during placement of a subcutaneous device. The first and second impedance measurements provide an indication of the lateral position of the tunneling tool between first electrode  272  and second electrode  274 . As the tunneling tool moves toward first electrode  272 , the impedance between first electrode  272  and the tunneling tool decreases and the impedance between second electrode  274  and the tunneling tool increases. As the tunneling tool moves toward second electrode  274 , the impedance between second electrode  274  and the tunneling tool decreases and the impedance between first electrode  272  and the tunneling tool increases. 
         [0055]    Embodiments provide an apparatus for assisting a physician in the placement of a subcutaneous device, such as a coil electrode for an implantable cardioverter-defibrillator (ICD) or other suitable subcutaneous device. The apparatus comprises a strap including an indentation for providing a mechanical guide for a tunneling tool. In addition, embodiments provide an electrical guide for assisting a physician in the placement of a subcutaneous device. The electrical guide is based on an impedance measurement or measurements between an electrode on a tunneling tool and an electrode or electrodes on the patient&#39;s skin. Embodiments also provide combinations of the mechanical guide and the electrical guide. 
         [0056]    Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes can be made in form and detail without departing from the spirit and scope of the present invention.