Abstract:
A system for pericardial lead implantation is disclosed herein. The system includes an implantation tool and a stimulation lead. The implantation tool includes a tubular body, a first lumen, a second lumen, a stylet or guidewire, a first port, and a second port. The first and second lumens longitudinally extend through tubular body. The first port is in communication with the first lumen, and the second port is in communication with the second lumen. The stylet or guidewire is longitudinally displaceable in the first lumen and across the first port. A tissue adhesive is selectively administrable through the second port via the second lumen. The stimulation lead includes a distal end and an engagement feature. Placing the engagement feature in the first port and causing the stylet or guidewire to displace in a first direction across the first port causes the lead to attach to the implantation tool. Displacing the stylet or guidewire in a second direction opposite the first direction allows the lead to detach from the implantation tool.

Description:
FIELD OF THE INVENTION 
     The present invention relates to medical devices and methods. More specifically, the present invention relates to devices and methods of implanting pacing and defibrillation leads. 
     BACKGROUND OF THE INVENTION 
     Factors (e.g., coronary sinus obstructions, absence of a suitable cardiac vein, high thresholds, or pheric nerve stimulation) warrant the need for an alternative to a transvenous approach to the implantation of left ventricle (“LV”) leads in congestive heart failure (“CHF”) patients in need of cardiac rhythm treatment (“CRT”). Historically, the alternative to a transvenous approach has entailed placement of an epicardial lead, which required invasive surgery and an associated hospital stay. 
     A minimally invasive pericardial approach to implanting a stimulating lead (e.g., a LV lead) has shown great promise as an alternative to the aforementioned transvenous and invasive surgery methods. In the pericardial approach, an introducer sheath is used to deliver a lead via a subxiphoid access to an implant location within the pericardial space. Visualization techniques, such as traditional fluoroscopy, MRI or endoscopy, are used to guide the introducer sheath to the implantation location within the pericardial space and to guide the final positioning of the lead. The pericardial approach is advantageous for a number of reasons. First, it does not require access to the vascular system. Second, it is minimally invasive and does not require surgical intervention and the associated general anesthesia. Third, it allows for a pathway to the entire exterior of the heart (e.g., any chamber, blood vessel or other anatomical feature of the heart) via a single entry point in the patient and in the pericardial sac. As a result, the minimally invasive pericardial approach offers greater simplicity and safety as compared to the transvenous and surgical approaches to stimulation lead implantation. 
     Despite the great promise shown by the minimally invasive pericardial approach, a current challenge continues to be an inability to reliably achieve a mechanically and electrically stable fixation of a stimulation lead at a preferred implantation site within the pericardial space. Consequently, there is a need in the art for a device and method that addresses the fixation challenge. 
     BRIEF SUMMARY 
     A system for pericardial lead implantation is disclosed herein. In one embodiment the system includes an implantation tool and a stimulation lead. The implantation tool includes a tubular body, a first lumen, a second lumen, a stylet or guidewire, a first port, and a second port. The first and second lumens longitudinally extend through tubular body. The first port is in communication with the first lumen, and the second port is in communication with the second lumen. The stylet or guidewire is longitudinally displaceable in the first lumen and across the first port. A tissue adhesive is selectively administrable through the second port via the second lumen. The stimulation lead includes a distal end and an engagement feature. Placing the engagement feature in the first port and causing the stylet or guidewire to displace in a first direction across the first port causes the lead to attach to the implantation tool. Displacing the stylet or guidewire in a second direction opposite the first direction allows the lead to detach from the implantation tool. 
     A method of pericardial lead implantation is disclosed herein. In one embodiment, the method includes placing an engagement feature of a stimulation lead in a first port of an implantation tool, extending a stylet or guidewire into the first port to attach the engagement feature to the implantation tool, and placing the attached implantation tool and stimulation lead in a pericardial space via a sub-xiphoid access. 
     A method of pericardial lead implantation is disclosed herein. In one embodiment, the method includes attaching a stimulation lead to an implantation tool, inserting the attached lead and tool into a pericardial space via a sub-xiphoid access, and applying a tissue adhesive from the tool to 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. 1  is a diagrammatic depiction of a distal end of the implant tool located within the pericardial space and coupled to a distal end of the lead. 
         FIG. 2  is a flow chart outlining the method of implanting the lead via the tool. 
     
    
    
     DETAILED DESCRIPTION 
     An implant tool  10  and method for implanting a stimulation lead  15  (e.g., pacing and/or defibrillation lead) are disclosed herein. The implant tool  10  and method are advantageous in that they allow a lead  15  to be slid into position within the pericardial space  20  and then dropped to achieve a mechanically and electrically stable atraumatic fixation to the implant location. 
     For a discussion of the device  10 , reference is made to  FIG. 1 , which is a diagrammatic depiction of a distal end  25  of the implant tool  10  located within the pericardial space  20  and coupled to a distal end  30  of the lead  15 . As shown in  FIG. 1 , the tool  10  includes a tubular body  35 , a first lumen  40 , a second lumen  45 , a first port  50  and a second port  55 . The tubular body  35  includes distal and proximal ends  25 ,  60 . The first lumen  40  extends the length of the tubular body  35  and daylights or opens at the distal and proximal ends  25 ,  60 . The first port  50  connects to the first lumen  40  and opens through the wall of the tubular body  35  near the distal end  25 . The second lumen  45  daylights or opens at the proximal end  60  and extends nearly the length of the tubular body  35  to connect to the second port  55 , which opens through the wall of the tubular body  35  near the distal end  25 . 
     As depicted in  FIG. 1 , the first lumen  40  slideably displaceably receives a stylet or guidewire  65 , which is used to direct the tool  10  to the implant site  70  within the pericardial space  20 . When the stylet or guidewire  65  is fully distally extended through the first lumen  40 , the stylet or guidewire  65  extends through the first port  50  and, as discussed later in this Detailed Description, is used to releasably couple the lead distal end  30  to the tool body  35 . 
     In one embodiment, the stylet or guidewire  65  is composed of a shape memory alloy (e.g., Nitinol®, etc.), a super polymer (e.g., polyether block amides (“PEBAX”), polyetheretherketone (“PEEK”), high density polyethylene (“HDPE”) etc.), or a metal or alloy (e.g., stainless steel, MP35N, Ti, or etc.). Regardless of the material from which the stylet or guidewire  65  is built, the stylet or guidewire  65  is deflectable to assist in its negotiating a path to the implantation site  70 . 
     As can be understood from  FIG. 1 , in one embodiment, the second lumen  45  slideably displaceably receives an extendable/retractable sheath  75 , which, as discussed later in this Detailed Description, is used to dispense a tissue adhesive through the second port  55 . In another embodiment, the tissue adhesive is administered through the second lumen  45  without the use of the sheath  75 . 
     As illustrated in  FIG. 1 , the pacing and/or defibrillation lead  15  includes a longitudinally extending body  80 , a proximal end  85  and a distal end  30 . In one embodiment, the lead body  80  is composed of silicone, polyurethane or a combination thereof. 
     The lead distal end  30  includes a member  90 , electrodes  95  mounted on the member  90 , and a connection feature  100  extending from the member  90 . In one embodiment, the member  90  is a planar disc  90  that has a circular, elliptical, rectangular, or etc. shape. The disc  90  has a superior side  105  and an inferior side  110 . When the lead  15  is implanted in the pericardial space  20 , the superior side  105  abuts against the interior surface of the pericardial sac  115 , and the inferior side  110  abuts against the exterior or myocardial surface of the heart wall  120 . In one embodiment, the disc  90  is a non-resorbable polymer mesh, weave, fabric, etc. (e.g., Dacron® mesh). In one embodiment, the disc  90  includes holes  125  that extend through the disc  90  to form receptacles for receiving the adhesive and bonding the disc  90  to the pericardial sac  115  and the heart wall  120 . 
     As indicated in  FIG. 1 , the connection feature  100  extends from the superior side  105  of the disc  90 , and the electrodes  95  extend from the inferior side  110  of the disc  90 . In one embodiment, the connection feature  100  is a hook or loop  100 , which, as discussed later in this Detailed Description, receives the stylet or guidewire  65  when the stylet or guidewire  65  is fully distally displaced within the first lumen  40 . In one embodiment, the connection feature  100  is formed of a metal or alloy (e.g., stainless steel, MP35N, Ti, or etc.). In one embodiment, the connection feature  100  is formed of a polymer (e.g., PEBAX, PEEK, HDPE, or etc.). 
     In one embodiment, the electrodes  95  are independently circuited. In one embodiment, the electrodes  95  are ganged together off of common circuit. In one embodiment, the electrodes  95  are in wireless communication with the implanted pacing and/or defibrillation device. 
     In one embodiment, the electrodes are formed of an electrically conductive metal or alloy (e.g., platinum-iridium alloy, titanium, or etc.). In one embodiment, the electrodes are formed of an electrically conductive polymer (e.g., silicone rubber impregnated with gold or platinum particles, or etc.). In one embodiment, at least one shock electrode  95  is located along the length of the lead body. In one embodiment, at least one shock electrode  95  is located on the disc  30  with the rest of the electrodes  95 , which, in one embodiment, are pacing and/or sensing electrodes  95 . 
     In one embodiment, a suitable amount of steroid (e.g., dexamethasone sodium phosphate, etc.) is accommodated proximal to the electrodes for low capture threshold levels. 
     For a discussion of a method of utilizing the tool  10  to implant the lead  15 , reference is made to  FIGS. 1 and 2 .  FIG. 2  is a flow chart outlining the method of implanting the lead  15  via the tool  10 . As can be understood from  FIGS. 1 and 2 , in one embodiment, an introducer sheath and the stylet/guidewire  65  extending there through are routed through a sub-xiphiod access  135  in a patient and into the pericardial space  20  via a pericardial access  140 . The stylet/guidewire  65 , a Touhy needle or other device known in the art and routed to the pericardial sac  115  via the introducer sheath is used to form the pericardial access  140 . 
     In one embodiment, the distal end of the introducer sheath and guidewire/stylet  65  are then positioned at the implant site  70  within the pericardial space  20  to guide the implant tool  10  and attached lead  15  to the implant site  70 . In another embodiment, the introducer lead is withdrawn and the guidewire/stylet  65  alone is used to guide the implant tool  10  and attached lead to the implant site  70 . 
     The lead loop  100  is positioned in the tool first port  50 , and the distal opening of the tool first lumen  40  receives the proximal end of the guidewire/stylet  65 , which still extends distally into implant site  70  within the patient [block  200 ]. As the tool tubular body  35  advances distally over the guidewire/stylet  65  via the tool first lumen  40 , the proximal end of the stylet/guidewire  65  proximally passes through the tool first lumen  40  and the lead loop  100  to attach the lead distal end  30  to the implant tool  10  [block  205 ]. 
     As the implant tool  10  and the attached lead  15  are distally advanced over the guidewire/stylet  65  to the implant site  70 , the tool  10  and attached lead  15  pass through the sub-xiphoid access  135  and the pericardial access  140  [block  210 ]. As previously mentioned, in one embodiment, as the tool  10  and attached lead  15  travel over the guidewire/stylet  65  to the implant site  70 , the tool  10  and attached lead  15  pass through the introducer sheath. In another embodiment, the tool  10  and attached lead  15  travel over the guidewire/stylet  65  to the implant site  70  without use of an introducer sheath. 
     Once the tool  10  and attached lead  15  are positioned as depicted in  FIG. 1  such that the tool distal end  25  and lead distal end  30  are located in the pericardial space  20  with the lead disc  90  flat between the tool  10  and the exterior surface of the heart wall  120 , the tool  10  is maneuvered to slide the attached lead distal end  30  into position at the preferred implant site  70  [block  215 ]. Once the inferior side  110  of the lead disc  90  is slid into place against the exterior surface of the heart wall  120  such that the lead electrodes  95  abut the exterior surface of the heart wall  120  at the implant site  70 , tissue adhesive is applied via the tool second lumen  45  to the superior surface  105  of the lead disc  110  [block  220 ]. The tissue adhesive passes into the disc openings  125  and forms a bond between the lead disc  105  and the exterior surface of the heart wall  120  [block  225 ]. 
     In one embodiment, the tissue adhesive is applied via the extendable/retractable sheath  75  located in the tool second lumen  45 . When the sheath  75  is proximally displaced within the tool second lumen  45 , the distal end of the sheath  75  opens into the second tool port  55 , which allows tissue adhesive to exit the sheath  75  onto the lead disc  90 . When the sheath  75  is returned to its fully distal position, tissue adhesive is prevented from exiting the second tool port  55 . 
     In one embodiment, the tissue adhesive is applied via the extendable/retractable sheath  75  located in the tool second lumen  45 . When the sheath  75  is proximally displaced within the tool second lumen  45 , a port  150  in the sidewall of the sheath  75  aligns with and opens into the second tool port  55 , which allows tissue adhesive to exit the sheath  75  onto the lead disc  90 . When the sheath  75  is returned to its fully distal position, the sheath port  150  and the second port  55  no longer align, and tissue adhesive is prevented from exiting the second tool port  55 . 
     In one embodiment, the tissue adhesive is applied via a sheath  75  that is rotatable within the tool second lumen  45  and includes a port  150  in the sidewall of the sheath  75 . When the sheath  75  is rotated such that its port  150  aligns with and opens into the second port  55 , tissue adhesive can exit the sheath  75  onto the lead disc  90 . When the sheath  75  is rotate back such that the sheath port  150  no longer aligns with the second port  55 , tissue adhesive is prevented from exiting the second tool port  55 . 
     In one embodiment, the tissue adhesive is applied via the tool second lumen  45  without the use of the extendable/retractable sheath  75 . In such an embodiment, the tissue adhesive is simply injected through the tool second lumen  45  when it is desired to apply the tissue adhesive to the lead disc  90 . When the application of tissue adhesive is no longer desired, the tissue adhesive injection is terminated. 
     In one embodiment, the adhesive is cyanoacrylate. In one embodiment, the adhesive is an extracellular matrix (“ECM”) (e.g., fibronectin, collagen, vitronectin, combinations thereof, etc.). 
     In one embodiment, the tool tubular body  35  further includes a third lumen. In such an embodiment, a fibrin glue (e.g., Tisseel®, Baxter®, etc.) is applied via the second lumen  45  (e.g., as already mentioned, by using the extendable/retractable sheath  75  in the second lumen  45  or simply using the second lumen  45  by itself), and an activator is applied via the third lumen in manner similar that used with the second lumen  45 . 
     Once the inferior side  110  of the lead disc  90  is bonded to the outer surface of the heart wall  120 , the stylet/guidewire  65  is proximally displaced within the first lumen  40  of the lead tubular body  35  a sufficient distance to cause the distal end of the stylet/guidewire  65  to clear the lead loop  100  and thereby free/drop the lead  15  from the tool  10  [block  230 ]. The implant tool  10  is then proximally displaced to withdraw the tool  10  from the pericardial space  20  and patient via the pericardial and sub-xiphoid accesses  140 ,  135  [block  235 ]. Once the tool distal end  25  vacates the pericardial space  20 , the elasticity of the pericardial sac  115  brings the inner surface of the pericardial sac  115  into abutting contact with the superior surface  105  of the lead disc  90 . The tissue adhesive bonds the inner surface of the pericardial sac  115  to the superior surface  105  of the lead disc  90 . As a result, lead disc  90  is sandwiched between, and bonded to, the pericardial sac  115  and the exterior surface of the heart wall  120 . 
     In one embodiment, the adhesive bonds provide an electrically and mechanically stable atraumatic fixation of the lead electrodes  95  to the implant site  70  that is sufficiently permanent for the operational life associated with the lead  15 . In one embodiment, the lead disc  90  is made of a non-resorbable mesh or weave material (e.g., Dacron®). As a result, tissue in-growth from the pericardial sac  115  and/or the outer surface of the heart wall  120  soon permanently attaches the lead disc  90  to the implantation site  70  to create an electrically and mechanically stable atraumatic fixation of the lead electrodes  95  to the implantation site  70 . 
     As can be understood from the preceding discussion, the lead implantation system disclosed herein is advantageous because it allows a lead  15  to be slid into place and dropped at the implantation site  70 , thereby facilitating quick and accurate placement of the lead electrodes  95 . The lead implantation system and method disclosed herein provides an easy and time efficient way of creating an electrically and mechanically stable atraumatic fixation of the lead electrodes  95  to the implantation site  70 . 
     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.