Abstract:
Various aspects of the present disclosure are directed toward methods, apparatuses, and systems that include an implantable medical device comprising an implantable lead, a suture sleeve having an interior surface defining a lumen of the suture sleeve that receives the implantable lead, and an engagement feature configured to non-removeably secure the suture sleeve to the implantable lead.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to Provisional Application No. 62/164,023, filed May 20, 2015, which is herein incorporated by reference in its entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    The present disclosure relates generally to implantable medical leads. More specifically, the disclosure relates to a suture sleeve for an implantable medical lead assembly. 
       BACKGROUND 
       [0003]    When functioning properly, the human heart maintains its own intrinsic rhythm and is capable of pumping adequate blood throughout the body&#39;s circulatory system. However, some individuals have irregular cardiac rhythms, referred to as cardiac arrhythmias, which can result in diminished blood circulation and cardiac output. One manner of treating cardiac arrhythmias includes the use of an implantable pulse generator (IPG) such as a pacemaker, an implantable cardioverter defibrillator (ICD), a cardiac resynchronization (CRT) device, or a subcutaneous implantable cardioverter defibrillator. Such devices typically rely on an implantable lead to convey electrical signals between the IPG and the heart. An implantable lead can additionally or alternatively be used to stimulate other nervous and/or musculature systems of the body. Whether for a cardiac lead or for a lead used elsewhere in the body, a suture sleeve can be provided along the lead to anchor the lead. 
       SUMMARY 
       [0004]    In Example 1, an implantable medical device comprising an implantable lead having a distal region, a proximal region, and an intermediate region therebetween; a suture sleeve having an interior surface defining a lumen of the suture sleeve, the lumen receiving the implantable lead, the suture sleeve comprising an exterior surface that defines at least one suture receiving track; and an engagement feature arranged on the implantable lead and configured to non-removeablely secure the suture sleeve to the implantable lead. 
         [0005]    In Example 2, the medical device of Example 1, wherein the suture sleeve comprises silicone and the implantable lead comprises polycarbonate. 
         [0006]    In Example 3, the medical device of Examples 1 or 2, wherein the engagement feature comprises an adhesive layer. 
         [0007]    In Example 4, the medical device of Example 3, wherein the adhesive layer comprises first durometer and the suture sleeve comprises a second durometer. 
         [0008]    In Example 5, the medical device of Example 4, wherein the first durometer is lower than the second durometer. 
         [0009]    In Example 6, the medical device of Example 1, wherein the suture sleeve further comprises at least one indentation along the interior surface of the suture sleeve, and the engagement feature comprises at least one radial projection comprising an upper surface, a lower surface, and sidewalls, the upper surface and the sidewalls being configured to provide a mechanical stop for the suture sleeve and engage the at least one indentation to secure the suture sleeve to the implantable lead. 
         [0010]    In Example 7, the medical device of Example 6, wherein the at least one radial projection comprises opposing sidewalls configured to engage the at least one indentation to secure the suture sleeve to the implantable lead. 
         [0011]    In Example 8, the medical device of Example 1, wherein the suture sleeve further comprises at least one cavity along the interior surface of the suture sleeve, and the engagement feature comprises at least one radial projection having rivets configured to engage a top surface of the suture sleeve on either side of the at least one cavity to secure the suture sleeve to the implantable lead. 
         [0012]    In Example 9, the medical device of any of the Examples 1-8, further comprising at least one electrode secured in the distal region of the implantable lead. 
         [0013]    In Example 10, a method for securing a suture sleeve to an implantable lead having a distal region, a proximal region, and an intermediate region therebetween, the method comprising: forming a suture sleeve having an interior surface defining a lumen of the suture sleeve, the lumen receiving the implantable lead, the suture sleeve comprising an exterior surface that defines at least one suture receiving track; forming an engagement feature on an exterior surface of the implantable lead; and securing the suture sleeve to the implantable lead by engaging the suture sleeve with the engagement feature 
         [0014]    In Example 11, the method of Example 10, wherein forming the engagement feature comprises providing an adhesive between the suture sleeve and the exterior surface of the medical lead. 
         [0015]    In Example 12, the method of Example 10, wherein forming the engagement feature comprises attaching at least one radial projection to the implantable lead, the at least one radial projection, and securing the suture sleeve to the implantable lead comprising engaging the suture sleeve with the at least one radial projection. 
         [0016]    In Example 13, the method of Example 10, wherein the at least one radial projection comprises a first radial projection and a second radial projection, and wherein securing the suture sleeve to the implantable lead comprises securing the suture sleeve between the first radial projection and the second radial projection. 
         [0017]    In Example 14, the method of Examples 10, 11, or 12, wherein securing the suture sleeve to the implantable lead comprises at least one of over-molding, pre-molding, or heat bonding the suture sleeve to the implantable lead. 
         [0018]    In Example 15, the method of Example 10, further comprising plasma treating the implantable lead prior to forming the engagement feature on the exterior surface of the implantable lead. 
         [0019]    In Example 16, an implantable medical device comprising: an implantable lead having a distal region, a proximal region, and an intermediate region therebetween; a suture sleeve having an interior surface defining a lumen of the suture sleeve, the lumen receiving the implantable lead, the suture sleeve comprising an exterior surface that defines at least one suture receiving track; and an engagement feature arranged on the implantable lead and configured to non-removeablely secure the suture sleeve to the implantable lead. 
         [0020]    In Example 17, the medical device of Example 16, wherein the suture sleeve comprises silicone and the implantable lead comprises polycarbonate. 
         [0021]    In Example 18, the medical device of Example 16, wherein the engagement feature comprises an adhesive layer. 
         [0022]    In Example 19, the medical device of Example 18, wherein the adhesive layer comprises a first durometer and the suture sleeve comprises a second durometer. 
         [0023]    In Example 20, the medical device of Example 18, wherein the first durometer is lower than the second durometer. 
         [0024]    In Example 21, the medical device of Example 16, wherein the suture sleeve further comprises at least one indentation along the interior surface of the suture sleeve, and the engagement feature comprises at least one radial projection having an upper surface, a lower surface, and sidewalls, the upper surface and the sidewalls being configured to provide a mechanical stop for the suture sleeve and engage the at least one indentation to secure the suture sleeve to the implantable lead. 
         [0025]    In Example 22, the medical device of Example 21, wherein the at least one radial projection comprises opposing sidewalls configured to engage the at least one indentation to secure the suture sleeve to the implantable lead. 
         [0026]    In Example 23, the medical device of Example 16, wherein the suture sleeve further comprises at least one cavity along the interior surface of the suture sleeve, and the engagement feature comprises at least one radial projection comprising rivets configured to engage a top surface of the suture sleeve on either side of the at least one cavity to secure the suture sleeve to the implantable lead. 
         [0027]    In Example 24, an implantable medical device comprising: an implantable lead having a distal region, a proximal region, and an intermediate region therebetween; an electrode arranged at the distal region of the implantable lead and configured to provide a stimulation pulse to a patient&#39;s heart; a suture sleeve having an interior surface defining a lumen of the suture sleeve, the lumen receiving the implantable lead, the suture sleeve comprising an exterior surface that defines at least one suture receiving track and at least one indentation along the interior surface of the suture sleeve; a sense electrode between the electrode and the suture sleeve; and at least one radial projection configured engage the at least one indentation to secure the suture sleeve to the implantable lead. 
         [0028]    In Example 25, the medical device of Example 24, wherein a gap between the suture sleeve and the sense electrode is between 2 mm and 15 mm. 
         [0029]    In Example 26, the medical device of Example 24, further comprising a second sense electrode at a distal tip of the implantable lead. 
         [0030]    In Example 27, the medical device of Example 24, wherein the electrode is configured to provide an electrical stimulation to a patient&#39;s heart. 
         [0031]    In Example 28, the medical device of Example 24, wherein the exterior surface of the suture sleeve comprises a surface roughness of between 45 and 75 Ra. 
         [0032]    In Example 29, the medical device of Example 24, wherein the suture sleeve comprises silicone and the at least one radial projection comprises at least one of polycin vorite (PCV), polyurethane, and polycarbonate. 
         [0033]    In Example 30, a method for securing a suture sleeve to an implantable lead having a distal region, a proximal region, and an intermediate region therebetween, the method comprising: forming a suture sleeve having a lumen defining an interior surface of the suture sleeve and sized to receive an implantable lead, the suture sleeve being arranged at the distal region of the implantable lead and comprising at least one suture receiving track on an exterior surface of the suture sleeve; forming an engagement feature on an exterior surface of the implantable lead; and securing the suture sleeve to the implantable lead by engaging the suture sleeve with the engagement feature 
         [0034]    In Example 31, the method of Example 30, wherein forming the engagement feature comprises providing an adhesive between the suture sleeve and the exterior surface of the medical lead. 
         [0035]    In Example 32, the method of Example 30, wherein forming the engagement feature comprises attaching at least one radial projection to the implantable lead, the at least one radial projection, and securing the suture sleeve to the implantable lead comprises engaging the suture sleeve with the at least one radial projection. 
         [0036]    In Example 33, the medical device of Example 32, wherein the at least one radial projection comprises a first radial projection and a second radial projection, and wherein securing the suture sleeve to the implantable lead comprising the securing the suture sleeve between the first radial projection and the second radial projection. 
         [0037]    In Example 34, the method of Example 30, wherein securing the suture sleeve to the implantable lead comprises at least one of over-molding, pre-molding, or heat bonding the suture sleeve to the implantable lead. 
         [0038]    In Example 35, the method of Example 30, further comprising plasma treating the implantable lead implantable lead prior to forming the engagement feature on the exterior surface of the implantable lead. 
         [0039]    While multiple embodiments are disclosed, still other embodiments of the present invention will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0040]      FIG. 1A  shows an implantable medical system including a suture sleeve as implanted in a patient. 
           [0041]      FIG. 1B  shows an enlarged schematic illustration the suture sleeve of  FIG. 1A . 
           [0042]      FIG. 2A  shows a cross sectional view, taken from  FIG. 1B , of a suture sleeve secured to an implantable by radial projections. 
           [0043]      FIG. 2B  shows an enlarged cross sectional view, taken from  FIG. 1B  as an alternative embodiment to that of  FIG. 2A , of an attachment mechanism having rivets for securing the suture sleeve to a lead. 
           [0044]      FIG. 2C  shows a cross sectional view, taken from  FIG. 1B  as an alternative embodiment to those of  FIGS. 2A-B , of a suture sleeve secure to a lead by a snap-fit mechanism. 
           [0045]      FIG. 2D  shows a schematic illustration of a suture sleeve secured to a lead by a securement ring. 
           [0046]      FIG. 2E  shows a schematic illustration of a suture sleeve secure to a lead by radial projection having end portions. 
           [0047]      FIG. 2F  shows a cross sectional view, taken from  FIG. 1B  as an alternative embodiment to those of  FIGS. 2A-C , of a suture sleeve secured to a lead by a plurality of radial projections for securing the suture sleeve to an implantable lead. 
           [0048]      FIG. 2G  shows a schematic illustration of a radial projection having a ring configuration. 
           [0049]      FIG. 2H  shows a schematic illustration of a radial projection having a spiral configuration. 
           [0050]      FIG. 2I  shows a cross sectional view, taken from  FIG. 1B  as an alternative embodiment to those of  FIGS. 2A-C  and  FIG. 2F , of a suture sleeve secured to a lead by an adhesive layer. 
           [0051]      FIG. 3  shows a schematic illustration of an implantable medical lead having a suture sleeve mounted thereon. 
       
    
    
       [0052]    While the full scope of this disclosure 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 invention to the particular embodiments described. On the contrary, the invention is intended to cover all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the appended claims. 
       DETAILED DESCRIPTION 
       [0053]      FIG. 1A  shows an implantable medical system  100 . The implanted medical system  100  includes a pulse generator  104  implanted within a patient. As shown, the pulse generator  104  can be connected to an implantable lead  108 .  FIG. 1A  shows the implantable medical system  100  arranged for delivering electrical stimulation to the heart  106 . The particular implantable medical system  100  shown is implanted subcutaneously along the patient&#39;s chest or abdomen, however other implant locations are possible. As shown in  FIG. 1A , the pulse generator  104  and the implantable lead  108  are implanted at an implant location that is outside of the ribcage. In various embodiments, the pulse generator  104  is a pacemaker, an implantable cardioverter/defibrillator (ICD), a cardiac resynchronization (CRT) device, a subcutaneous implantable cardioverter defibrillator, a neurostimulator, or any other implantable medical device for delivering a therapy, and may be configured to deliver one or more of pacing, CRT, defibrillation, and neurostimulation therapies, amongst other options. The pulse generator  104  may additionally or alternatively be configured for sensing within the body, such as sensing bioelectrical signals and/or other physiological parameters. 
         [0054]    The entirety of the implantable lead  108  is implanted subcutaneously, but outside of the ribcage. As such, in various embodiments, no part of the implantable lead  108  comes into contact with the heart. In some other embodiments, at least part of the implantable lead  108  may extend into the ribcage, such as to make contact with the heart. 
         [0055]    One or more portions of the implantable lead  108  may be secured in place with a suture sleeve  102 . The suture sleeve  102  can be secured to the implantable lead  108  prior to beginning surgery, such as in manufacturing of the implantable lead  108  without involvement of a surgeon or other medical professional. Securing the suture sleeve  102  to the implantable lead  108  during manufacturing may allow for a more efficient implantation procedure as a surgeon or trained medical professional would not have to position the suture sleeve  102  on the implantable lead  108  while operating. Further, securing the suture sleeve  102  to the implantable lead  108  in this manner may also provide for an accurate and defined arrangement of the suture sleeve  102  on the implantable lead  108 . 
         [0056]    The implantable lead  108  can include an electrode  110 . The electrode  110  shown in  FIG. 1A  is a defibrillation electrode having a large surface area. Additionally or alternatively, smaller pace and/or sense electrodes, such as ring electrodes, can be deposed on the implantable lead  108 . While a single electrode  110  is shown, it will be understood that a greater number of electrodes and/or different types of electrodes can be provided on the implantable lead  108 . The flexible lead body can be formed from a polymeric tube. 
         [0057]    In various embodiments, the implantable lead  108  is inserted into the patient through a first incision (entry site) formed in the side of the patient. A stiff tube (e.g., an introducer, not shown) can be inserted into and through the first incision and the implantable lead  108  can be moved through the tube toward the sternum of the patient. A second incision can be made near an upper portion of the sternum of the patient. The second incision can allow for an access point for a physician to position the distal end of the implantable lead  108 . In addition, a third incision can be made near a lower portion of the sternum. The third incision allows for access to the suture sleeve  102 , which is provided to secure the implantable lead  108  in place. Other suitable access sites may be utilized in various other embodiments, and the incisions may be made in any order. Once the suture sleeve  102  is appropriately positioned, the physician may secure the implantable lead  108  in place by tying sutures  112 ,  113 ,  114 ,  115  to the suture sleeve  102 , and threading the sutures  112 ,  113 ,  114 ,  115  within the body. 
         [0058]      FIG. 1B  shows an enlarged schematic illustration of the suture sleeve  102  of  FIG. 1A . The suture sleeve  102  includes a lumen (and other internal components) that defines an interior surface of the suture sleeve. The lumen and the implantable lead  108  are sized relative to one another such that the implantable lead  108  can be received within the lumen of the suture sleeve  102 . An exterior surface of the suture sleeve  102  can include one or more receiving tracks  118 ,  122 ,  126 ,  130 . Each track  118 ,  122 ,  126 ,  130  can be defined by opposing sidewalls  120 ,  124 ,  128 ,  132 . The sidewalls  120 ,  124 ,  128 ,  132  can hold a suture within the suture receiving track  118 ,  122 ,  126 ,  130  to minimize movement between the suture and the suture sleeve  102 . While four tracks  118 ,  122 ,  126 ,  130  are shown in the embodiment of  FIG. 1B , it will be understood that no tracks, a single track, two tracks, three tracks, or any number of tracks can alternatively be provided. One or more sutures can be placed within each track  118 ,  122 ,  126 ,  130  during an implantation procedure to secure the implantable lead  108  in place within the body. Each suture (as shown above with reference to  FIG. 1A ) can also penetrate and/or loop around tissue to secure the suture sleeve  102  to the tissue. A knot can be tied in each suture after the suture is wrapped around the suture sleeve  102 . The suture sleeve  102  can prevent the sutures from contacting the lead  108  to prevent damaging the implantable lead  108  while also securing the lead  108  at an implant site. Further, in certain embodiments, the suture sleeve  102  can have a surface roughness of between 45 and 75 Ra to enhance securement of the suture with the suture sleeve  102 . 
         [0059]    The suture sleeve  102  can be formed from polymeric material, such as silicone. The material of the suture sleeve  102  may not include properties that allow for heat welding or chemical bonding of the suture sleeve  102  to the implantable lead  108 . Silicone, for example, may not readily adhere to other materials. However, it is advantageous to form the suture sleeve  102  of silicone, or like materials, due to the biocompatible and robust properties of silicone and similar materials. The suture sleeve  102  may be non-removeably secured to the implantable lead  108  via one or more features as further discussed herein. 
         [0060]      FIG. 2A  shows an enlarged cross sectional view of a suture sleeve  202  secured to an implantable lead  214  by radial projections  204 ,  206 . The cross sectional view can represent, for example, a cross-sectional view taken from the line A-A shown in  FIG. 1B . The cross-sectional view in  FIG. 2A  shows the cross-sectional aspects of the suture sleeve  202  and a lumen  212  of the implantable lead  214 , however, the other internal components (e.g., electrical components) of the implantable lead  214  are omitted. The suture sleeve  202  is mounted on an implantable lead  214 . The suture sleeve  202  is secured to the implantable lead  214  by one or more radial projections  204 ,  206 . The radial projections  204 ,  206  may be a continuous ring around the implantable lead  214  (as is shown in  FIG. 1B ), or, the radial projections  204 ,  206  may be only on portions of the implantable lead  214 . The radial projection  204 ,  206  can have sidewalls  208 ,  210  that bound an upper surface  207 ,  209  of the radial projections  204 ,  206 . 
         [0061]    The suture sleeve  202  can also include one or more indentations  211 ,  213 . The one or more indentations  211 ,  213  may be the opposite (e.g., mirror) of the structure of the radial projections  204 ,  206  and interface therewith. The sidewalls  210  can be curved such that differentiation between the upper surface  207 ,  209  of the radial projections  204 ,  206  are gradually formed. Further, the sidewalls  208 ,  210  can be formed at a steeper angle (e.g., 90 degrees) with respect to the upper surface  207 ,  209 . In either instance, the indentations  211 ,  213  can be provided along the interior surface the suture sleeve  202 , and can be complementary to the radial projections  204 ,  206 . The raised profile of the radial projections  204 ,  206  shown in  FIG. 2A  provides a mechanical stop for the suture sleeve  202 , and the radial projections  204 ,  206  engage the one or more indentations  211 ,  213  to secure the suture sleeve  202  to an implantable lead  214 . 
         [0062]    As noted above with reference to  FIG. 1B , the radial projections  204 ,  206  are provided on an implantable lead  214 . The suture sleeve  202  can be secured thereto by sliding the suture sleeve  202  along the implantable lead  214  until the encountering the radial projections  204 ,  206 . The suture sleeve  202  is forced over the radial projections  204 ,  206 , and slid further along the implantable lead  214  until the radial projections  204 ,  206  engages the indentations  211 ,  213 . If more than one radial projections  204 ,  206  is provided, the suture sleeve  202  is forced further along the implantable lead  214  until each of the radial projections  204 ,  206  is provided within the counterpart indentations  211 ,  213 . As noted above, the radial projections  204 ,  206  can be formed around the entire circumference of the implantable lead  214 . In this manner, during manufacturing, the suture sleeve  202  may be slid along the body of the implantable lead  214 , and the radial projections  204 ,  206  will engage the indentations  211 ,  213  regardless of the rotational positioning of the suture sleeve  202 . The indentations  211 ,  213  may be formed within the suture sleeve  202  prior to placing the suture sleeve  102  on the suture sleeve, or the indentations may be formed as a result of placing the suture sleeve  102  over the respective radial projections  204 ,  206 . The indentations  211 ,  213  may be formed as a ring-like indentation along the entire interior circumference of the suture sleeve  202 . 
         [0063]      FIG. 2B  shows an enlarged cross sectional view of a fixation feature for securing a suture sleeve  222  to an implantable lead  221 . The cross sectional view can represent, for example, a cross-sectional view taken from the line A-A shown in  FIG. 1B . The cross-sectional view in  FIG. 2B  shows the cross-sectional aspects of the suture sleeve  222  and a lumen  220  of the implantable lead  221 , however, the other internal components (e.g., electrical components) of the implantable lead  221  are omitted. The suture sleeve  222  can be secured to the implantable lead  221  by one or more radial projections  216 ,  217 ,  218 ,  219 . Each radial projection  216 ,  217 ,  218 ,  219  can include a rivet  223 ,  224 ,  225 ,  226 . An upper surface of the rivets  223 ,  224 ,  225 ,  226  can be substantially parallel with a top surface of the suture sleeve  222 . In other instances, an upper surface of the rivets  223 ,  224 ,  225 ,  226  may be provided such that portions thereof on top of a top surface of the suture sleeve  222 . The rivet  223 ,  224 ,  225 ,  226  can project axially outward from the radial projections  216 ,  217 ,  218 ,  219  such that a top surface of the rivets  223 ,  224 ,  225 ,  226  are parallel (or substantially parallel and/or angled) relative to an upper surface of the suture sleeve  222 . The suture sleeve  222  can wedge between the rivets  223 ,  224 ,  225 ,  226  and a main body portion of the radial projections  216 ,  217 ,  218 ,  219 . In addition, the suture sleeve  222  can include indentations  231 ,  232 ,  233 ,  233  (or cavity) that are formed in portions of or as a ring-like indentation/cavity along the entire interior circumference of the suture sleeve  222 . In instances where the suture sleeve  222  includes one or more cavities, the suture sleeve  222  may first be placed on the implantable lead  221 . Once the suture sleeve  222  is in the desired location along the implantable lead  221 , the radial projections  216 ,  217 ,  218 ,  219  can be formed on the implantable lead  221 . In this manner, the rivets  223 ,  224 ,  225 ,  226  can be provided along the outside surface of the suture sleeve  222  and hold the suture sleeve  222  against the implantable lead  221 . In instances where the suture sleeve  222  includes a plurality of indentations  231 ,  232 ,  233 ,  233 , an equal number of the radial projections  216 ,  217 ,  218 ,  219  will also be provided to secure the suture sleeve  222  to the implantable lead  221 . In addition, the suture sleeve  222  may include suture one or more receiving tracks  227 ,  228 ,  229 ,  230  that may hold a suture to secure the implantable lead  221  in place within the body 
         [0064]      FIG. 2C  shows a cross sectional view of a snap-fit mechanism for securing a suture sleeve  234  to an implantable lead  236 . The cross sectional view can represent, for example, a cross-sectional view taken from the line A-A shown in  FIG. 1B . The cross-sectional view in  FIG. 2C  shows the cross-sectional aspects of the suture sleeve  234  and a lumen  235  of the implantable lead  236 , however, the other internal components (e.g., electrical components) of the implantable lead  236  are omitted. The implantable lead  236  can include one or more radial projections  237 ,  238  that can be bonded to the implantable lead  236 . As shown, the radial projections  237 ,  238  are formed as a continuous ring around the circumference of the implantable lead  236 . Indentations  239 ,  240  in the suture sleeve  234  can be formed complementary to the radial projections  237 ,  238  to receive the radial projections  237 ,  238 . Similar to the radial projections  237 ,  238 , the indentations  239 ,  240  are formed as a continuous ring. The radial projections  237 ,  238  can be snap-fit with the indentations  239 ,  240  in the inner surface of the implantable lead  236  as a mechanism to secure the suture sleeve  234  to the implantable lead  236 . 
         [0065]    The radial projections  237 ,  238  and the indentations  239 ,  240  may be formed from the same material (e.g., polyurethane or polycarbonate). The suture sleeve  234  may be formed as an upper and lower portion, and guided onto the rivets  226 . Thus, in securing the suture sleeve  234  to the implantable lead  236 , as is shown in  FIG. 2C , the suture sleeve  234  is snapped onto the radial projections  237 ,  238  such that the indentations  239 ,  240  and the radial projections  237 ,  238  are matched. In addition, the suture sleeve  234  may include one or more receiving tracks  241 ,  242 ,  243 ,  244  that may hold a suture to secure the implantable lead  236  in place within the body. The tracks  241 ,  242 ,  243 ,  244  may be formed as a continuous ring around the exterior surface of the suture sleeve  234 . 
         [0066]      FIG. 2D  shows a schematic illustration of a suture sleeve  246  and radial projection  247  having a securement ring  248 . The radial projection  247  shown in  FIG. 2D  is a single structure arranged that includes the securement ring  248 . As shown in  FIG. 2D , the suture sleeve  246  includes two portions  254 ,  255  on either side of the securement ring  248 . Similar to the example shown in  FIG. 2B , the securement ring  248  can include an adhesive to secure the suture sleeve  246  to an implantable lead  249 . The securement ring  248  can contact both portions  254 ,  255  of the suture sleeve  246  via the securement ring  248 , and secure the suture sleeve  246  to the implantable lead  249 . The radial projection  247  and the securement ring  248  may be bonded together. The radial projection  247  may be secured to the implantable lead  249 , and secured to the securement ring  248 . The securement ring  248  secures the suture sleeve  246  to the radial projection  247 . The radial projection  247  may be secured to the implantable lead  249  by first plasma treating the implantable lead  2479 , and subsequently bonding the radial projection  247  thereto. In addition, the suture sleeve  246  may include suture one or more receiving tracks  250 ,  251 ,  252 ,  253  that may hold a suture to secure the implantable lead  249  in place within the body. The tracks  250 ,  251 ,  252 ,  253  may be formed as a continuous ring around the exterior surface of the suture sleeve  246 . 
         [0067]      FIG. 2E  shows a schematic illustration of a suture sleeve  256  and radial projection having end portions  259 . The end portions  259  can be provided on either side of the suture sleeve  256  to secure the suture sleeve  256  to an implantable lead  258 . End edges  260 ,  261  of the end portions  259  can overlap portions of the suture sleeve  256 , or can be provided such that the end edges  260 ,  261  of the end portions  259  contact the edges of the suture sleeve  256 . During manufacturing of, the suture sleeve  256  may be positioned on the implantable lead  258 . Prior to or after position the suture sleeve  256  on the implantable lead  258 , the end portions  259  may be secured on the implantable lead  258  and the edges  260 ,  261  will engage portions of the suture sleeve  256  to secure the suture sleeve  256  to the implantable lead  258 . In addition, the suture sleeve  256  may include suture one or more receiving tracks  262 ,  263 ,  264 ,  265  that may hold a suture to secure the implantable lead  258  in place within the body. The tracks  262 ,  263 ,  264 ,  265  may be formed as a continuous ring around the exterior surface of the suture sleeve  256 . 
         [0068]      FIG. 2F  shows a cross sectional view, taken from  FIG. 1B , of a suture sleeve  266  and a plurality of radial projections  268  for securing the suture sleeve  266  to an implantable lead  270 . The cross sectional view can represent, for example, a cross-sectional view taken from the line A-A shown in  FIG. 1B . The cross-sectional view in  FIG. 2F  shows the cross-sectional aspects of the suture sleeve  266  and a lumen  271  of the implantable lead  270 , however, the other internal components (e.g., electrical components) of the implantable lead  270  are omitted. The plurality of radial projections  268  can be formed as part of a single material that is notched for flexibility. The plurality of radial projections  268  are bonded to the implantable lead  270 , and the suture sleeve  266  can be provided over the plurality of radial projections  268 . The radial projections  268  can be secured directly to the implantable lead  270 . In addition, the radial projections  268  may be heat bonded to the implantable lead  270 , or secured by other methods of discussed herein. In addition, the suture sleeve  266  may include suture one or more receiving tracks  272 ,  273 ,  274 ,  275  that may hold a suture to secure the implantable lead  270  in place within the body. The tracks  272 ,  273 ,  274 ,  275  may be formed as a continuous ring around the exterior surface of the suture sleeve  266 . 
         [0069]      FIG. 2G  shows a schematic illustration of a radial projection  276  having a circular configuration. The radial projection  276  shown in  FIG. 2G  can also be formed of a single piece of material. A suture sleeve (not shown) can be secured to an implantable lead  278  by bonding or otherwise securing the suture sleeve over the radial projection  276 . Due to the circular configuration of the radial projection  276 , the suture sleeve can be provided with suture receiving tracks, such as those shown and discussed above with reference to  FIG. 1B , via the securement of a suture sleeve over the radial projection  276 . The radial projection  276  can have a notched configuration that can be used in relation to embodiments of the present invention. In certain embodiments, the circular shape can be provided with a taper. The taper can occur from both ends of the radial projection  276  such that the centermost portion is raised apart from the implantable lead  278  as compared to the end portions of the radial projection  247 .  FIG. 2H  shows a schematic illustration of radial projection  280  having a spiral configuration. The radial projection  280  shown in  FIG. 2H  may be formed of a single piece of material. A suture sleeve (not shown) can be secured to an implantable lead  282  by bonding or otherwise securing the suture sleeve over the radial projection  280 . Similar to the configuration discussed with reference to  FIG. 2G , the suture sleeve can be provided with suture receiving tracks, such as those shown and discussed above with reference to  FIG. 1B , by way of the securement of a suture sleeve over the radial projection  280 . The radial projection  280  can have a notched spiral configuration that can be used in relation to embodiments of the present invention. In certain embodiments, the spiral shape can be provided with a taper. The taper can occur from both ends of the radial projection  280  such that the centermost portion is raised apart from the implantable lead  282  as compared to the end portions of the radial projection  276 . 
         [0070]      FIG. 2I  shows a cross sectional view, taken from  FIG. 1B  as an alternative embodiment to those of  FIGS. 2A-F , of a suture sleeve  284  secured to a lead  288  by an adhesive layer  286 . The cross sectional view can represent, for example, a cross-sectional view taken from the line A-A shown in  FIG. 1B . The cross-sectional view in  FIG. 2I  shows the cross-sectional aspects of the suture sleeve  284  and a lumen  287  of the implantable lead  288 , however, the other internal components (e.g., electrical components) of the implantable lead  288  are omitted. As shown, the suture sleeve  284  may be directly attached to the implantable lead  288  via the adhesive layer  286 . The suture sleeve  284  may be positioned along the implantable lead  288 , and the adhesive layer  286  may be provided between the suture sleeve  284  and the implantable lead  288 . The adhesive layer  286  may be provided along a portion of the suture sleeve  284 , as shown in  FIG. 2I , or the adhesive layer  286  may be provided along the circumference of the suture sleeve  284 . The adhesive layer  286  may be a medical adhesive. The outer surface of the implantable lead  288  may be treated, prior to securing the suture sleeve  284  thereto, to increase the ability of the surface to non-removeably secure the suture sleeve  284 . The suture sleeve  284  may then be bonded to the implantable lead  288  via the adhesive layer  286 . More specifically, the outer surface of the implantable lead  288  may be plasma treated (or otherwise cleaned), and the suture sleeve  284  may be bonded thereto via the adhesive layer  286 . In certain instances, the adhesive layer  286  is as flexible or more flexible than the suture sleeve  284 . In addition, the adhesive layer  286  may have a first durometer, and the suture sleeve  284  may have a second durometer. The first durometer may be lower than the second durometer. In addition, the suture sleeve  284  may include suture one or more receiving tracks  289 ,  290 ,  291 ,  292  that may hold a suture to secure the implantable lead  288  in place within the body. The tracks  289 ,  290 ,  291 ,  292  may be formed as a continuous ring around the exterior surface of the suture sleeve  284 . 
         [0071]    In each of the arrangements shown in  FIGS. 2A-2I , the radial projections may be attached to the implantable lead by over molding or pre-molding the radial projection, and subsequently bonding (e.g., heat bonding, polycin vorite bonding) the radial projection to the implantable lead. In certain other embodiments, the suture sleeve may be molded and subsequently bonded to the implantable lead using a medical adhesive after priming the implantable lead with a bonding agent, and plasma treating the implantable lead. In these such embodiments, the radial projection can be the medical adhesive. Thus, the radial projection can be provided with a low profile, and not include raised portions described herein. 
         [0072]    In addition, the suture sleeve and the radial projections can be formed of various different materials. In certain embodiments, the suture sleeve and the radial projections are formed of different materials. For instance, the suture sleeve can be formed of silicone, and the radial projections can be formed of polycin vorite (PCV), polyurethane, or polycarbonate. Other suitable materials are also contemplated. 
         [0073]      FIG. 3  shows a schematic illustration of an implantable medical lead  300  including a suture sleeve  302 . The implantable medical lead  300  has a distal region  304 , a proximal region  306 , and an intermediate region therebetween. The intermediate region is not shown in  FIG. 3  (as is represented by the fragmented depiction of the lead  300 ). The proximal region  306  includes a connector  308  for the implantable medical lead  300  to connect to a pulse generator (as described, for example, with reference to  FIG. 1A ). The suture sleeve  302  is arranged at the distal region  304  of the implantable medical lead  300 , along with an electrode  309 , and a first sense electrode  310 , and a second sense electrode  312 . The electrode  309  is configured to provide a stimulation pulse to a patient&#39;s heart. The electrode  309  can provide the stimulation in response to the first sense electrodes  310  and the second sense electrode  312  determining that the patient&#39;s heart has an irregular rhythm. 
         [0074]    The second sense electrode  312  is provided nearer a distal end tip of the implantable medical lead  300  than the first sense electrodes  310 , which is provided between the suture sleeve  302  and the electrode  309 . The gap between the suture sleeve  302  and the first sense electrode  310  is between 2 mm and 15 mm. In the embodiment shown in  FIG. 3 , the gap between the suture sleeve  302  and the first sense electrode  310  is 7.5 mm. The suture sleeve  302  is secured on the implantable medical lead  300  such that the suture sleeve  302  will not cover the first sense electrode  310  and thereby interfere with the function of the first sense electrode  310 . The suture sleeve  302  is secured to the implantable medical lead  300  using radial projections, as shown and discussed above with reference to  FIGS. 2A-2I . 
         [0075]    The suture sleeve  302  is secured to the implantable medical lead  300 , for example, by sliding the suture sleeve  302  along the implantable medical lead  300  from the proximal region  306  to the distal region  304 . The suture sleeve  302  has lumen that an interior surface of the suture sleeve  302 , and that is sized to receive the implantable medical lead  300 . The radial projection, used to secure the suture sleeve  302  to the implantable medical lead  300 , is bonded to the implantable medical lead  300  at a position nearer the proximal region  306  than the first sense electrode  310 . The suture sleeve  302  is slid along the length of the implantable medical lead  300  until reaching the radial projection. The suture sleeve  302  can be engaged with the radial projection by forcing the suture sleeve  302  over the structure. 
         [0076]    The suture sleeve  302  can also be snap-fit to the secured to the implantable medical lead  300  by snap-fitting the suture sleeve  302  over the radial projection (as shown in  FIG. 2C ), or the suture sleeve  302  can be directly molded to the implantable medical lead  300 . In addition, the rivet features, as described above with reference to  FIG. 2B , or radial protrusions may be formed using a high durometer epoxy resin. The rivets or radial projections may be formed by filling the voids in a suture sleeve with epoxy, and then allowing it to cure and harden to form the rivets or radial projections. 
         [0077]    The suture sleeves described above and otherwise wherein can be modified in view of any other embodiment presented herein, as the present application provides examples of various features that are selectively useable together and are not presented in a restrictive sense. Various modifications and additions can be made to the embodiments discussed without departing from the scope of the present invention. For example, while the embodiments described above refer to particular features, the scope of this invention 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 invention is intended to embrace all such alternatives, modifications, and variations as falling within the scope of the claims, together with all equivalents thereof.