Abstract:
An implantable cardiac electrotherapy lead is disclosed herein. In one embodiment, the lead includes a tubular body having a distal end with a first soft resilient member. The member extends or is extendable from the distal end radially outward relative to a longitudinal axis of the tubular body.

Description:
FIELD OF THE INVENTION 
   The present invention relates to medical apparatus and methods. More specifically, the present invention relates to implantable cardiac electrotherapy leads and methods of using such leads. 
   BACKGROUND OF THE INVENTION 
   Cardiac electrotherapy leads are implanted within various locations of a heart to provide pacing and/or defibrillation electrotherapy. Cardiac perforation of the right ventricle (“RV”) wall is a risk associated with all transvenous lead implantations to the RV apical site, especially active fixation leads, leads with smaller diameters, and defibrillation leads. The likelihood of perforation is a function of the lead and/or stylet configuration and the dexterity of the implanting surgeon. 
   In rare cases, the distal end of a lead acts as a spear that pierces the RV wall, either during implantation of the lead or in the succeeding months. If a lead perforates the myocardium, acute patient symptoms can include pericardial effusion, cardiac tamponade, pericarditis, or even death. Additionally, a lead that has perforated the myocardium may be non-functioning and may cause chest pain or pneumothorax. 
   The RV apical wall can be as thin as one millimeter thick, and the right atrium (“RA”) appendage can be less than one millimeter thick. In contrast, a helix extending from the distal tip of a lead can be two millimeters long when fully extended. As a result, it is possible for the helix to cross the entire thickness of a RV apical wall or a RA appendage wall. 
   There is a need in the art for an implantable cardiac electrotherapy lead configured to reduce the likelihood of cardiac perforation. There is also a need in the art for a method of making and deploying such a lead. 
   BRIEF SUMMARY 
   An implantable cardiac electrotherapy lead is disclosed herein. In one embodiment, the lead includes a tubular body having a distal end with a first soft resilient member. The member extends or is extendable from the distal end radially outward relative to a longitudinal axis of the tubular body. 
   An implantable cardiac electrotherapy lead is disclosed herein. In one embodiment, the lead includes a tubular body having a distal end with first and second members. The members are extendable from the distal end radially outward relative to a longitudinal axis of the tubular body. 
   A method of implanting an implantable cardiac electrotherapy lead is disclosed herein. In one embodiment, the method includes distally passing a distal end of the lead through an introducer sheath when the distal end has a reduced diameter, and expanding the diameter of the distal end upon exiting a distal end of the introducer sheath with the distal end of the lead. 
   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. As will be realized, the invention is capable of modifications in various aspects, all without departing from the spirit and scope of the present invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1A  is an isometric view of one embodiment of the distal end of a lead tubular body having members radially outwardly extending from the distal end. 
       FIG. 1B  is an isometric view of one embodiment of the distal end of a lead tubular body having members radially outwardly extending from the distal end. 
       FIG. 2A  is an isometric view of one embodiment of the distal end of a lead tubular body having members radially outwardly extending from the distal end. 
       FIG. 2B  is an isometric view of one embodiment of the distal end of a lead tubular body having members radially outwardly extending from the distal end. 
       FIG. 2C  is an isometric view of one embodiment of the distal end of a lead tubular body having members radially outwardly extending from the distal end. 
       FIG. 2D  is an isometric view of one embodiment of the distal end of a lead tubular body having members radially outwardly extending from the distal end. 
       FIG. 2E  is an isometric view of one embodiment of the distal end of a lead tubular body having members radially outwardly extending from the distal end. 
       FIG. 3A  is an isometric view of one embodiment of the distal end of a lead tubular body having a member radially outwardly extending from the distal end. 
       FIG. 3B  is an isometric view of one embodiment of the distal end of a lead tubular body having a member radially outwardly extending from the distal end. 
       FIG. 4A  is an isometric view of one embodiment of the distal end of a lead tubular body having a radially outwardly expandable sleeve in a non-expanded state. 
       FIG. 4B  is an isometric view of one embodiment of the distal end of a lead tubular body having a radially outwardly expandable sleeve in an expanded state. 
       FIG. 5A  is a sectional view of one embodiment of the distal end of a lead tubular body having a radially outwardly expandable sleeve in a non-expanded state. 
       FIG. 5B  is a sectional view of one embodiment of the distal end of a lead tubular body having a radially outwardly expandable sleeve in an expanded state. 
       FIG. 6A  is a sectional view of one embodiment of the distal end of a lead tubular body having a radially outwardly expandable sleeve in a non-expanded state. 
       FIG. 6B  is a sectional view of one embodiment of the distal end of a lead tubular body having a radially outwardly expandable sleeve in an expanded state. 
       FIG. 7A  is an isometric view of one embodiment of the distal end of a lead tubular body having radially outwardly expandable members in a closed non-expanded configuration. 
       FIG. 7B  is an isometric view of one embodiment of the distal end of a lead tubular body having radially outwardly expandable members in an open expanded configuration. 
       FIG. 8A  is an isometric view of one embodiment of the distal end of a lead tubular body having a radially outwardly expandable balloon in an expanded configuration. 
       FIG. 8B  is a side view of one embodiment of the distal end of a lead tubular body having a radially outwardly expandable balloon in an expanded configuration. 
       FIG. 9A  is a sectional view of one embodiment of the distal end of a lead tubular body having members radially inwardly and outwardly extending from the distal end. 
       FIG. 9B  is an isometric view of one embodiment of the distal end of a lead tubular body having members radially inwardly and outwardly extending from the distal end. 
       FIG. 9C  is a sectional of view one embodiment of the distal end of a lead tubular body having members radially inwardly and outwardly extending from the distal end. 
       FIG. 10A  is an isometric view of one embodiment of the distal end of a lead tubular body having members radially inwardly and outwardly extending from the distal end. 
       FIG. 10B  is a sectional of view one embodiment of the distal end of a lead tubular body having members radially inwardly and outwardly extending from the distal end. 
       FIG. 11A  is an isometric view of one embodiment of the distal end of a lead tubular body having members radially inwardly and outwardly extending from the distal end. 
       FIG. 11B  is an isometric view of one embodiment of the distal end of a lead tubular body having members radially inwardly and outwardly extending from the distal end. 
       FIG. 12A  is an isometric view of one embodiment of the distal end of a lead tubular body having members radially inwardly and outwardly extending from the distal end. 
       FIG. 12B  is a sectional view of one embodiment of the distal end of a lead tubular body having members radially inwardly and outwardly extending from the distal end. 
       FIGS. 13A-13D  are a series of side views of the lead distal end deploying from a non-expanded state ( FIG. 13A ), wherein the lead tubular body is capable of being routed through an introducer sheath, to an expanded state ( FIG. 13D ). 
       FIG. 13E  is an enlarged side view of the lead distal end depicted in  FIG. 13D . 
       FIG. 13F  is a diagrammatic isometric view of a wire frame on a tubular body distal end, wherein the wire frame is a cage in a non-deployed state. 
       FIG. 13G  is a side view of the tubular body distal end and frame depicted in  FIG. 15F , wherein the frame is in a non-deployed state. 
       FIG. 13H  is the same view as  FIG. 15G , except the frame is deployed. 
       FIG. 14A  is a diagrammatic isometric view of a wire frame on a tubular body distal end, wherein the wire frame employs wire rings or wings and the wire frame is in a non-deployed state. 
       FIG. 14B  is the same view as  FIG. 14A , except the frame is deployed. 
   

   DETAILED DESCRIPTION 
   The present application describes tubular body  10  of an implantable cardiac electrotherapy lead (e.g., a bradycardia lead, tachycardia lead, or etc.). The lead tubular body  10  has a distal end  15  configured to reduce the likelihood of myocardial perforation when the lead distal end  15  contacts a myocardial surface during the implantation of the lead within the heart of a patient. In some embodiments, the lead tubular body  10  includes a distal end  15  that has a modifiable diameter that can be increased as the distal end  15  approaches a myocardial surface. In some embodiments, the lead tubular body  10  includes a distal end  15  that provides a soft material interface for contacting the myocardial surface. In some embodiments, the lead tubular body  10  includes a distal end  15  having resistance features that provide resistance to the distal end  15  penetrating the myocardial surface. In some embodiments, the lead tubular body  10  includes a distal end  15  employing any two or more of the aforementioned techniques for reducing the likelihood of the distal end  15  perforating a myocardial surface. 
   For a discussion regarding various embodiments of the lead tubular body  10  employing a cushioning distal end  15  with a modifiable diameter, reference is made to  FIGS. 1A-3B .  FIGS. 1A-3B  are isometric views of various embodiments of the distal end  15  of a lead tubular body  10  having members  20  radially outwardly extending from the distal end  15 . As shown in  FIGS. 1A-3B , the distal end  15  of the lead tubular body  10  includes one or more radially outwardly extending members  20 , a distal end face  25 , a recess  30  or pocket  32 , a helix  35 , a helix lumen  40 , a bevel  45  or lip  47 , and an outer circumferential surface  50 . 
   As can be understood from  FIGS. 1A-3B , the outer circumferential surface  50  extends proximally from the distal end  15  generally uniformly to define the surface of the lead tubular body  10 . The helix  35  serves as a mechanism for fixing the lead distal end  15  to a myocardial surface. The helix  35  is distally/proximally displaceable within the helix lumen  40  to extend or retract the helix  35  within the lumen  40 . The distal end face  25  extends about the lumen  40  and forms the most distal surface of the lead tubular body  10 . 
   As illustrated in  FIGS. 1A-3B , the members  20  extend radially outwardly from the distal end  15  and include a distal face  55 , a proximal face  60  and an outer edge or rim  65 . As indicated in  FIGS. 1A ,  1 B,  2 A,  2 D, and  3 B, each member  20  is positioned on the distal end  15  such that the member distal face  55  radially outwardly extends from the distal end face  25  of the lead tubular body  10  as a continuous uninterrupted surface to the member outer rim  65 . Alternatively, as depicted in  FIGS. 2B ,  2 C,  2 E and  3 A, each member  20  is positioned on the distal end  15  such that the member distal face  55  radially outwardly extends from the distal end  15  at a point proximally offset a small distance from the distal end face  25 , thereby defining a rim or lip  70  extending circumferentially about, and generally perpendicularly to, the distal end face  25 . 
   As can be understood from  FIGS. 1A ,  1 B,  3 A and  3 B, in various embodiments, the tubular body outer circumferential surface  50  extends generally uniformly distally from the tubular body proximal end until reaching the bevel  45  where the diameter of the lead tubular body  10  transitions to a smaller diameter to form the recess  30 . The recess  30  is defined between the proximal face(s)  60  of the member(s)  20  and the bevel  45 . The recess  30  and bevel  45  extend about the circumference of the lead tubular body  10 . 
   In various alternative embodiments, as can be understood from  FIGS. 2A-2E , the tubular body outer circumferential surface  50  extends generally uniformly distally from the tubular body proximal end until nearing the vicinity of the members  20  where lips  47  define pockets  32  in the tubular body outer circumferential surface  50 . In one embodiment, each pocket  32  aligns with and matches the shape and size of its corresponding member  20 . 
   As can be understood from  FIGS. 1A-3B , the members  20  are resiliently flexible and formed from a polymer material such as silicone rubber, polyurethane, silicone-polyurethane-copolymer (“SPC”), or etc. Thus, when the lead tubular body  10  is distally extended through an introducer sheath, the members  20  deflect proximally to reside within the recess  30  or seat within the corresponding pocket  32 , as the case may be, to allow the diameter of the lead distal end  15  to reduce to generally match the diameter of the rest of the lead tubular body  10 . As a result, the lead tubular body  10  can pass through an introducer sheath sized for the passage of a typical lead. Once the lead distal end  15  emerges from the distal end of the introducer sheath, the members are free to radially outwardly extend from the recess  30  or their respective pockets  32 . Thus, the lead tubular body  10  is advantageous because it can be deployed via a typically sized introducer sheath while providing a distal end  15  with a substantially enlarged diameter to reduce the likelihood of myocardial perforation by the lead tubular body  10  when being implanted. 
   As shown in  FIGS. 1A and 1B , in various embodiments, the members  20  are generally rectangular and separated by V-shaped gaps  75 . The members  20  taper as they extend towards their outer rim  65 . As indicated in  FIG. 1A , in one embodiment, the members  20  are concave in orientation such that the members  20  curve slightly distally. As illustrated in  FIG. 1B , in one embodiment, the members  20  are convex in orientation such that the members  20  curve slightly proximally. 
   As illustrated in  FIGS. 2A-2E , in various embodiments, the members  20  are generally elongated, radiate outwardly from the outer circumferential surface  50  of the tubular body  10 , terminate with arcuate shaped outer rims  65 , and are generally uniform in thickness along their entire lengths. The corresponding pockets  32  are similarly shaped and arranged to accept the members  20 . 
   As indicated in  FIGS. 3A-3B , in various embodiments, the member  20  will be a generally continuous circular disk  20  radially outwardly extending from the distal end  15 . In one embodiment, as shown in  FIG. 3B , the circular disk member  20  is concentric with the tubular body  10  in that the member  20  is centered about the lumen  40 . In another embodiment, circular disk member  20  is eccentric with the tubular body  10  in that the center of the circular disk member  20  is offset from the lumen  40 . 
   As can be understood from  FIGS. 1A-3B , depending on the embodiment, the distal end  15  can have any number of members  20  radially extending from the distal end  15 . Ultimately, in each of the embodiments depicted in  FIGS. 1A-3B , the members  20  radially outwardly extend from the distal end  15  to create an enlarged deflectable footprint that reduces the likelihood of myocardial perforation by the distal end  15 . Additionally, the members  20  fold proximally, thereby allowing the lead tubular body  10  to be deployed through a typically sized introducer sheath. 
   For a discussion regarding various other embodiments of the lead tubular body  10  employing a cushioning distal end  15  with a modifiable diameter, reference is made to  FIGS. 4A-6B .  FIGS. 4A-6B  are isometric and sectional views of various embodiments of the distal end  15  of a lead tubular body  10  having a member or sleeve  20  that is radially outwardly expandable from the distal end  15 . As shown in  FIGS. 4A-6B , the distal end  15  of the lead tubular body  10  includes a radially outwardly expandable sleeve  20 , a distal end face  25 , a helix  35 , a helix lumen  40 , and an outer circumferential surface  50 . 
   As can be understood from  FIGS. 4A-6B , the outer circumferential surface  50  extends proximally from the distal end  15  generally uniformly to define the surface of the lead tubular body  10 . The helix  35  serves as a mechanism for fixing the lead distal end  15  to a myocardial surface. The helix  35  is distally/proximally displaceable within the helix lumen  40  to extend or retract the helix  35  within the lumen  40 . The distal end face  25  extends about the lumen  40  and forms the most distal surface of the lead tubular body  10 . 
   As shown in  FIGS. 4A ,  5 A and  6 A, when the member or sleeve  20  is in its non-deployed or non-expanded state, the outer circumferential surface  80  of the sleeve  20  is generally continuously uniform or flat with the outer circumferential surface  50  of the lead tubular body  10 . In other words, when in its non-expanded state, the diameter of the member or sleeve  20  is generally the same as the diameter of the rest of the lead tubular body  10 . 
   As indicated in  FIGS. 4B ,  5 B and  6 B, when the member or sleeve  20  is in its deployed or expanded state, the outer circumferential surface  80  of the sleeve  20  expands outwardly from its non-expanded state, thereby increasing the diameter of the distal end  15  across the expanded member  20 . In its expanded state, the sleeve  20  has a distal face  55  and a proximal face  60 . In one embodiment, the sleeve  20  is positioned on the distal end  15  such that the sleeve distal face  55  radially outwardly extends from the distal end  15  at a point proximally offset a small distance from the distal end face  25 , thereby defining a rim or lip  70  extending circumferentially about, and generally perpendicularly to, the distal end face  25 . 
   As can be understood from  FIGS. 4A and 4B , in one embodiment, a ring of swellable material is located below the surface of the member or sleeve  20 , which is made of a resilient polymer such as silicone rubber, polyurethane, SPC, or etc. The swellable material is activated or caused to swell by exposure to a biological fluid. In one embodiment, the swellable material is a silicone, poly-vinyl alcohol (“PVA”) hydrogel, or other swellable material molded into a ring with the inner diameter of the member  20 . 
   The lead tubular body  10  is distally passed through an introducer sheath in its non-expanded state so the lead tubular body  10  can pass through a typically sized introducer sheath without resistance. Once the lead distal end  15  exits the distal end of the introducer sheath and is exposed to biological fluid, the swellable material swells and the member or sleeve  20  expands from its non-expanded state ( FIG. 4A ) to its expanded state ( FIG. 4B ). As a result, the footprint of the distal end  15  of the lead tubular body  10  increases, and the likelihood of myocardial perforation by the distal end  15  is reduced. 
   In one embodiment, the molded ring can swell to a larger outer diameter due to an impregnated swelling agent such as a steroid. Dexamethasone (“DexA”) and dexamethasone sodium phosphate (“DSP”) can swell approximately 10% and 35% by diameter, respectively. The use of a steroid as the swelling agent may also provide therapy to reduce inflammation of the surrounding tissue. 
   As can be understood from  FIGS. 5A and 5B , in one embodiment, the member  20  is a sleeve made of a preformed polymer material such as silicone rubber, polyurethane, SPC, or etc. As shown in  FIG. 5A , the preformed member or sleeve  20  is maintained in the non-deployed or non-expanded state via a dissolvable cylinder  85  that is used to keep the preformed sleeve  20  stretched out flat to be of a generally uniform diameter with the rest of the outer circumferential surface  50  of the lead tubular body  10 . The lead tubular body  10  distally passes through an introducer sheath in its non-expanded state ( FIG. 5A ). Once the lead distal end  15  exits the distal end of the introducer sheath and is exposed to biological fluid (e.g., blood), the dissolvable cylinder  85  begins to dissolve. Once the dissolvable cylinder  85  is sufficiently dissolved, the preformed sleeve  20  is free to assume its preformed expanded configuration ( FIG. 5B ), thereby increasing the footprint of the lead distal end  15  and reducing the likelihood of myocardial perforation by the lead distal end  15 . 
   In one embodiment, the dissolvable cylinder  85  is formed of Mannitol, a slightly sweet alcohol, C 6 H 8 (OH) 6 , which dissolves in approximately three to five minutes. In other embodiments, the cylinder  85  is formed of other dissolvable materials. 
   In one embodiment, which is depicted in  FIGS. 6A and 6B  and is similar to that discussed with respect to  FIGS. 5A and 5B , the dissolvable cylinder  85  is a helical spacer  85  helically positioned between a helical header component  90 . The helical header component  90  is a flat wire  90  that is maintained in a stretch/extended state by the coils  85  of the dissolvable helical spacer  85 , which are positioned between the coils  90  of the helical flat wire  90 . When the helical flat wire  90  is maintained in the extended state by the dissolvable spacer  85 , the preformed sleeve  20  is maintained in its non-deployed or non-expanded state such that is diameter generally conforms to the diameter of the rest of the lead tubular body  10 . Once the dissolvable spacer  85  is exposed to biological fluid, the spacer eventually dissolves and no longer maintains the helical flat wire  90  in an extended state. In other words, the helical flat wire  90  is free to return to its natural length. As a result, the preformed sleeve  20  is free to expand to the deployed state, thereby increasing the footprint of the lead distal end  15  and reducing the likelihood of myocardial perforation by the lead distal end  15 . 
   For a discussion regarding another embodiment of the lead tubular body  10  employing a cushioning distal end  15  with a modifiable diameter, reference is made to  FIGS. 7A-7B .  FIGS. 7A-7B  are isometric views of various embodiments of the distal end  15  of a lead tubular body  10  having members or helix covers  20  that are radially outwardly expandable from the distal end  15 . As shown in  FIGS. 7A-7B , the distal end  15  of the lead tubular body  10  includes covers  20  that can be opened into a radially outwardly expanded configuration, a distal end face  25 , a helix  35 , a helix lumen  40 , and an outer circumferential surface  50 . 
   As can be understood from  FIGS. 7A-7B , the outer circumferential surface  50  extends proximally from the distal end  15  generally uniformly to define the surface of the lead tubular body  10 . The helix  35  serves as a mechanism for fixing the lead distal end  15  to a myocardial surface. The helix  35  is distally/proximally displaceable within the helix lumen  40  to extend or retract the helix  35  within the lumen  40 . 
   As can be understood from  FIGS. 7A and 7B , the members or helix covers  20  pivot from a closed longitudinally extending configuration to an opened radially outwardly extended configuration. As shown in  FIG. 7A , when in the non-deployed or non-expanded configuration, the covers  20  reside in a longitudinally extending position where the covers  20  are closed against each other in an opposed fashion along a seam  95 . The extreme distal ends  100  of the covers  20  are arcuate and form the extreme distal end of the lead tubular body  10  when the covers  20  are in the non-deployed configuration. In one embodiment, the covers  20  are shell-like and, when in the non-deployed configuration, enclose the helix  35  and form a circumferential surface with a diameter that generally matches the diameter of the outer circumferential surface  50  of the lead tubular body  10 . 
   In one embodiment, although the covers  20  are shell-like and can enclose the helix  35 , the helix  35  remains retracted within the tubular body  10  proximal of the distal end face  25  until the covers  20  are opened in anticipation of helix deployment. Upon opening the covers  20 , the helix  35  is distally displaced to extend distally past the distal end face  25 . The helix  35  is then anchored in the heart tissue for implantation of the lead tubular body  10 . 
   The members or covers  20  are hinged to the rest of the tubular body  10  and are biased to open into the deployed or expanded configuration illustrated in  FIG. 7B . The implanting physician closes the covers  20  together into the non-deployed configuration and inserts the lead distal end  15  into the proximal end of an introducer sheath. The lead tubular body  10  is distally passed through the introducer sheath in the non-deployed configuration. When the distal end  15  of the lead tubular body  10  exits the distal end of the introducer sheath, the covers  20  bias into the deployed configuration depicted in  FIG. 7B . 
   As illustrated in  FIG. 7B , in one embodiment, when the members or covers  20  bias into the open, deployed configuration, the covers  20  are approximately 180 degrees apart. Each cover  20  includes seam faces  100  that generally align with the distal face  25  of the lead tubular body  10  when in the deployed configuration. Thus, the seam faces  100  and the distal end face  25 , which extends about the lumen  40 , combine to form the most distal surface of the lead tubular body  10 . 
   As can be understood from  FIG. 7A , when the members or covers  20  close together in the non-deployed configuration, the seam faces  100  abut to form the seam  95 . While in the non-deployed configuration, the arcuate distal ends  100  of the covers  20  form the most distal end of the lead tubular body  10 . 
   In one embodiment, the shell-like members or covers  20  are formed from a polymer material such as silicone rubber, polyurethane, SPC, or etc. In other embodiments, the covers  20  are formed in generally the same manner as the rest of the lead tubular body  10 . 
   As can be understood from  FIGS. 7A and 7B , when the members or covers  20  are in the closed, non-deployed configuration, the lead tubular body  10  can pass through a typically sized introducer sheath. When the covers  20  are in the open, deployed configuration, the footprint of the lead distal end  15  is increased, thereby reducing the likelihood of myocardial perforation by the lead distal end  15 . 
   For a discussion regarding another embodiment of the lead tubular body  10  employing a cushioning distal end  15  with a modifiable diameter, reference is made to  FIGS. 8A-8B .  FIGS. 8A-8B  are, respectively, an isometric view and a side view of various embodiments of the distal end  15  of a lead tubular body  10  having a member or balloon  20  that is radially outwardly expandable from the distal end  15 . As shown in  FIGS. 8A-8B , the distal end  15  of the lead tubular body  10  includes a member or balloon  20  that can be inflated into a radially outwardly expanded configuration, a helix  35 , a helix lumen  40 , and an outer circumferential surface  50 . 
   As can be understood from  FIGS. 8A and 8B , the lead tubular body  10  distally travels through an introducer sheath when the balloon  20  is in an un-inflated or non-expanded state. When in the un-inflated state, the balloon  20  does not substantially exceed the diameter of the rest of the lead tubular body  10  and, as a result, the lead tubular body  10  is able to pass unimpeded through a typically sized introducer sheath. 
   Once the lead distal end  15  exits the introducer distal end, the balloon  20  can be inflated via a fluid (e.g., compressed air, carbon dioxide, saline, etc.) to assume the expanded or deployed state, as depicted in  FIGS. 8A and 8B . The balloon  20  is inflated via a fluid supply (e.g., a pump) in fluid communication with the balloon  20  via one or more fluid conveying lumens extending the length of the lead tubular body  10 . In the inflated or expanded state, the balloon  20  increases the footprint of the lead distal end  15  and creates a cushion, thereby reducing the likelihood of the lead distal end  15  perforating the myocardial surface. 
   In one embodiment, the balloon  20  is formed of polymer materials such as polyethylene terephthalate (“PET”), latex rubber, silicone rubber, or other expandable polymers. 
   As indicated in  FIGS. 8A and 8B , in various embodiments, the balloon  20  is pear or spherically shaped. As shown in  FIG. 8A , in one embodiment, the distal surface  105  of the balloon  20  is located at or slightly proximal to the distal end surface  25  of the lead tubular body  10 . In one embodiment, the distal surface  105  of the balloon  20  is located slightly distal of the distal end surface  25  of the lead tubular body  10 . A lumen  110  defined in the balloon  20  coaxially aligns with, and extends down to, the helix lumen  40  to provide a path for the extension of the helix  35  into the myocardial surface. 
   For a discussion regarding various embodiments of the lead tubular body  10  employing a cushioning distal end  15  with a modifiable diameter, reference is made to  FIGS. 9A-12B .  FIGS. 9A-12B  are isometric and sectional views of various embodiments of the distal end  15  of a lead tubular body  10  having members  20 ,  115  radially outwardly and inwardly extending from the distal end  15 . As shown in  FIGS. 9A-12B , the distal end  15  of the lead tubular body  10  includes one or more radially outwardly extending members  20 , a radially inwardly extending member or flange  115 , a distal end face  25 , a helix  35 , a helix lumen  40 , a bevel  45  or lip  47 , and an outer circumferential surface  50 . In some embodiments, as depicted in  FIGS. 10A and 10B , the distal end  15  also includes a recess  30 . 
   As can be understood from  FIGS. 9A-12B , the outer circumferential surface  50  extends proximally from the distal end  15  generally uniformly to define the surface of the lead tubular body  10 . The helix  35  serves as a mechanism for fixing the lead distal end  15  to a myocardial surface. The helix  35  is distally/proximally displaceable within the helix lumen  40  to extend or retract the helix  35  within the lumen  40 . The distal end face  25  extends about the lumen  40  and forms the most distal surface of the lead tubular body  10 . 
   As illustrated in  FIGS. 9A-12B , the members  20  extend radially outwardly from the distal end  15  and include a distal face  55  and a proximal face  60 . As shown in  FIGS. 9A-10B , the members  20  also include an outer rim  65 . As shown in  FIGS. 12A and 12B , the members  20  also include an outer surface  80 . As shown  FIGS. 11A and 11B , the members  20  also include an outer peak  120 . 
   As indicated in  FIGS. 9A-11B , each member  20  is positioned on the distal end  15  such that the member distal face  55  radially outwardly extends from the distal end face  25  of the lead tubular body  10  as a continuous uninterrupted surface to the member outer rim  65  or member outer peak  120 , as the case may be. Alternatively, as depicted in  FIGS. 12A-12B , each member  20  is positioned on the distal end  15  such that the member distal face  55  radially outwardly extends from the distal end  15  at a point proximally offset a small distance from the distal end face  25 , thereby defining a rim or lip  70  extending circumferentially about, and generally perpendicularly to, the distal end face  25 . 
   As can be understood from  FIGS. 9A-9C , and  12 A- 12 B, in various embodiments the tubular body outer circumferential surface  50  extends generally uniformly distally from the tubular body proximal end until reaching the proximal faces of the members  20 . As can be understood from  FIGS. 10A-11B , in various embodiments, the tubular body outer circumferential surface  50  extends generally uniformly distally from the tubular body proximal end until reaching a bevel  45  or lip  47  where the diameter of the lead tubular body  10  transitions to a smaller diameter to form the recess  30 . The recess  30  is defined between the proximal face(s)  60  of the member(s)  20  and the bevel  45  or lip  47 . The recess  30 , bevel  45 , and lip  47  extend about the circumference of the lead tubular body  10 . 
   As can be understood from  FIGS. 9A-12B , the members  20  are resiliently flexible and formed from a polymer material such as silicone rubber, polyurethane, SPC, or etc. As can be understood from  FIGS. 9A-9C  and  11 A- 12 B, in embodiments where the members  20  do not radially extend outward from the tubular body  10  a great distance, the members  20  simply defect proximally or squish radially inward to allow the lead distal end  15  to pass through a typically sized introducer sheath. As can be understood from  FIGS. 10A-10B , in embodiments where the members  20  do radially extend outward a substantial distance, the members  20  fold proximally into the recess  30  to allow the lead distal end  15  to pass through a typically sized introducer sheath. 
   As can be understood from  FIGS. 9C and 10B , in one embodiment, the members  20  are located a distance d of approximately 0.02 inch distal the more rigid portion of the tubular body  10 . Such an arrangement allows the members  20  to freely collapse inward when the tubular body  10  is pushed through an introducer. Due to their ability to collapse inwardly, the members  20  can be made larger than they would otherwise be capable of being made. 
   As can be understood from  FIGS. 9A-12B , once the lead distal end  15  exits the introducer distal end, the members are free to resiliently return to their radially outwardly expanded conditions. Thus, the lead tubular body  10  is advantageous because it can be deployed via a typically sized introducer sheath while providing a distal end  15  with a substantially enlarged diameter to reduce the likelihood of myocardial perforation by the lead tubular body  10  when being implanted. 
     FIGS. 9A-10B  depict various embodiments employing generally thin members  20 , which are flexibly resilient, but have solid cross-sections. As shown in  FIGS. 10A and 10B , in various embodiments, the members  20  are generally rectangular and separated by V-shaped gaps  75 . Each member  20  is generally of constant thickness in each dimension as it extends to its outer rim  65 . As indicated in  FIGS. 10A-10B , in one embodiment, the members  20  are convex in orientation such that the members  20  curve slightly proximally. As indicated in  FIGS. 9A-9C , in various embodiments, the member  20  is a generally continuous radially outward extending ring or flange  20  that convexly curves from the distal end face  25  to the outer rim  65 . 
     FIGS. 11A-12B  depict various embodiments employing generally bump-like members  20  that are flexibly resilient, but may or may not have hollow cross-sections. As illustrated in  FIGS. 11A and 11B , each member  20  is a nub or bump  20  with distal and proximal faces  55 ,  60  that curve generally equal distances to meet at a peak  120 . 
   As depicted in  FIGS. 12A and 12B , the nub or bump is hollow, but in other embodiments will have a solid cross-section. The member&#39;s distal face  55  is generally perpendicular to the outer circumferential surface  50 . The member&#39;s proximal face  60  has a gradual slope leading up to the outer surface  80 . 
   As indicated in  FIGS. 9A-12B , in various embodiments, the distal face  25  extends radially inward to define a radially inwardly extending flange  115 . While the flange  115  extends into the helix lumen  40 , the helix  35  can displace distally/proximally as needed within the lumen  40  because the helix  35  simply deflects the flange  115 , which is made of a flexible resilient polymer material such as silicone rubber, polyurethane, SPC, or etc. The surface area of the radially inwardly extending flange  115  and the surface area of the radially outwardly extending member  20  combine to substantially increase the footprint of the lead distal end  15 . As a result, the likelihood of the lead distal end  15  perforating the myocardial surface is reduced. The likelihood of perforation is further reduced by the cushioning of the soft and resilient material used to form the various members  20 , flanges  115  and header portion of the lead distal end  15 . Also, the shape and protrusion of the various members  20  increases the resistance to penetration presented by a tubular body  10 . 
   As shown in  FIGS. 9B-9C  and  12 A- 12 B, in various other embodiments, the soft distal end  15  is made more identifiable via fluoroscopy by blending natural or dyed TiO 2  or barium sulfate into the silicone rubber forming the soft distal end  15 . In one embodiment, the soft distal end  15  extends between approximately 0.015 inches to approximately 0.02 inches distally from the header of the lead tubular body  10 . 
   For a discussion of another embodiment of the lead distal end  15 , reference is made to  FIGS. 13A-13D .  FIGS. 13A-13D  are a series of side views of the lead distal end  15  deploying from a non-expanded state ( FIG. 13A ), wherein the lead tubular body  10  is capable of being routed through an introducer sheath, to an expanded state ( FIG. 13D ).  FIG. 13E  is an enlarged view side view of the lead distal end  15  depicted in  FIG. 13D . 
   As shown in  FIG. 13D , in one embodiment, the lead distal end  15  includes a wire frame  200  that is biased to expand after exiting an introducer sheath. In one embodiment, the wire frame  200  is made with a shape-memory metal such as Nitinol. In one embodiment, the wire frame  200  provides a resilient spring-like function between the lead distal end  15  and the myocardial surface, thereby reducing the likelihood of myocardial surface perforation by the lead distal end  15 . In one embodiment, the wire frame  200  provides a substantially increased diameter that reduces the likelihood of myocardial penetration by the lead distal end  15 . 
   The number of wires  205  and joints  210  can have multiple configurations to optimize the spring constant, reduce the risk of wire fracture, increase footprint in contact with the myocardium, and minimize the risk of myocardial perforation. In order to limit thrombosis or unacceptable interactions with the myocardium, a cover  215  made of polytetrafluoroethylene (“PTFE”) or another biocompatible material may be used to encapsulate the wire frame  200 . 
   In one embodiment, the wire frame  200  has an expanded diameter or width dimension of between approximately five millimeters and 15 millimeters. In another embodiment, the wire frame  200  has an expanded diameter or width dimension of between approximately 15 millimeters and 32 millimeters. Such wire frames  200  when collapsed, as shown in  FIG. 13A , are capable of passing through a  10 F introducer sheath. The gradual deployment of the wire frame  200  from the non-expanded state ( FIG. 13A ) to the fully expanded state ( FIG. 13D ) can be seen in the series depicted in  FIGS. 13A-13D . 
   As shown in  FIG. 13E , the lead distal end  15  extends through the frame  200  from the rest of the lead tubular body  50 . The helix  35  is extendable from the distal end of the frame  200 . 
   For a discussion regarding a wire frame configuration for use with the embodiment depicted in  FIGS. 13A-13E , reference is made to  FIGS. 13F-13H .  FIG. 13F  is a diagrammatic isometric view of a wire frame  200  on a tubular body distal end  15 , wherein the wire frame  200  is a cage in a non-deployed state.  FIG. 13G  is a side view of the tubular body distal end  15  and frame  200  depicted in  FIG. 13F , wherein the frame  200  is in a non-deployed state.  FIG. 13H  is the same view as  FIG. 13G , except the frame  200  is deployed. 
   As shown in  FIGS. 13F and 13G , when in a non-deployed state, the frame  200  is elongated, extending distally from the tubular body distal end  15  and having a diameter generally the same as the tubular body distal end  15 . The elongated configuration of the non-deployed frame  200  allows the frame  200  to pass through the lumen of an introducer used to deliver the lead tubular body  10 . 
   In one embodiment, the walls of the introducer lumen maintain the frame  200  in the non-deployed state as the lead distal end  15  passes through the introducer. Upon exiting the introducer lumen, the frame  200  is free to assume its deployed state, as reflected in  FIG. 13H . 
   In its deployed state, the length of the frame  200  is substantially reduced, allowing the helix  35  to access the heart tissue for anchoring purposes once the helix  35  is distally extended from the tubular body distal end  15 . In its deployed state, the width or diameter of the frame  200  is substantially increased as compared to the frame&#39;s non-deployed state. More specifically, the width or diameter of the frame  200  in the deployed state is substantially greater than the diameter of the lead distal end  15 . As a result, the contact area of the lead distal end  15  is substantially increased, reducing the likelihood of cardiac perforation. 
   In one embodiment, the frame  200  is an assembly of wire members  205  made from an elastic or shape memory material, such as Nitinol. The wires  205  intersect with each other at joints  210  to form a frame  200  with a hexagon-shaped distal end and cross-section. The frame  200  is biased to transform from the non-deployed state ( FIGS. 13F and 13G ) to the deployed state ( FIG. 13H ). 
   In one embodiment, as shown in  FIGS. 13A-13E , a cover  215  extends over and is stitched or otherwise attached to the frame  200 . In one embodiment, the cover  215  is formed of PTFE or ePTFE. 
   For a discussion of another embodiment employing an expandable wire frame concept, reference is made to  FIGS. 14A-14B .  FIG. 14A  is a diagrammatic isometric view of a wire frame  500  on a tubular body distal end  15 , wherein the wire frame  500  employs wire rings or wings  505  and the wire frame  500  is in a non-deployed state.  FIG. 14B  is the same view as  FIG. 14A , except the frame  500  is deployed. 
   As shown in  FIGS. 14A and 14B , in one embodiment, the wire frame  500  includes multiple wire rings or wings  505 . As shown in  FIG. 14A , when in a non-deployed state, the wings  505  fold back against the outer circumferential surface  50  of the lead tubular body  10 . As indicated by the arrows in  FIG. 14B , when expanding into the deployed state, the wings  505  unfold distally to project generally radially outward from the tubular body distal end  15 . As a result, the contact area of the lead distal end  15  is substantially increased, reducing the likelihood of cardiac perforation. 
   In one embodiment, as the lead tubular body  10  is being delivered to the lead implantation site, the lumen walls of the introducer maintain the wings  505  in the non-deployed state depicted in  FIG. 14A . Distally extending the distal end  15  from the introducer lumen allows the wings  505  to expand into the deployed state depicted in  FIG. 14B . Once the wings  505  are fully deployed, the helix  35  can be distally extended, as shown in  FIG. 14B . 
   In one embodiment, the wings  505  are made from a shape memory material, such as Nitinol. In one embodiment, the frame  500  is formed of one, two, three or more wings  505 . 
   Although the present invention has been described with reference to preferred embodiments, persons skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.