Patent Publication Number: US-2006015163-A1

Title: Lead extender for implantable device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
      This application claims the benefit of prior U.S. Application No. 60/589,148, which was filed on Jul. 19, 2004. 
    
    
     BACKGROUND OF THE INVENTION  
      The present invention generally relates to implantable electro-stimulation devices for use in the human body. More specifically, the present invention relates to the leads that extend from the device to the organ being stimulated.  
      The human heart normally maintains its own intrinsic rhythm in order to consistently pump a proper supply of blood throughout the body&#39;s circulatory system. However, some people are afflicted with irregular cardiac rhythms, or cardiac arrhythmias, resulting in diminished blood circulation. Drug therapy is one mode of treatment for cardiac arrhythmias. Unfortunately, drug therapy is not effective for treating all cardiac arrhythmias. Hence, alternative modes of treatment including implantable electrotherapy devices, such as pacemakers and defibrillators, are utilized.  
      Patients with bradyarrythmias, or symptomatic or slow beating of the heart, are often treated with pacemakers. These devices deliver timed sequences of low energy electrical stimuli to the heart via leads having one or more electrodes placed about the heart. With proper timing of the electrical stimuli, heart contractions are regulated such that the heart contracts at a proper rate, greatly improving blood supply throughout the body&#39;s circulatory system.  
      Patients with malignant tachyarrhythmia, or potentially life threatening fast beating of the heart, are often treated with implantable cardioverter defibrillators. These devices deliver high-energy electrical stimuli called defibrillation countershock to the heart. The countershock interrupts the tachyarrhythmia allowing the heart to establish a perfusing rhythm, which allows the heart to completely fill with blood before pumping. Other implantable electrotherapy devices include pacer/defibrillators, which combine the functions of pacemakers and defibrillators, drug delivery devices, and other systems designed for diagnosing and treating arrhythmias.  
      In addition to the above heart conditions that are treated with electrical stimulation signals, various muscle and nerve conditions also benefit from electrical stimulation. For example, electrical signals may be used for pain management, where signals effect nerve system reaction. Further, electrical systems also include muscular stimulation devices, which provide appropriate signals to the body to aid in injury recovery. In another example, drug delivery is achieved using electrical signals to “drive” certain drugs into the body.  
      Conventional implantable electrode leads used together with implantable electrotherapy devices are commonly known. An implantable electrode lead is generally comprised of at least one electrode for supplying an electrical stimulation pulse or sensing an electrically evoked response of the heart, an electrical connector for connecting the electrode lead to an implantable electrotherapy device, and a lead body inserted between the electrode and the electrical connector for transmitting an electrical signal between the electrode and the implantable electrotherapy device.  
      Implantation surgery involves a first step of connecting distal ends of the leads to the organ to be treated. In the case of the heart, an organ that violently and continually beating, the attachment between the lead and the muscle must be able to endure both the physical movement of the heart and the changing density of the heart muscle as it flexes and relaxes.  
      The next step is to find a suitable location to implant the device. Defibrillators are usually placed in the chest wall under the collarbone. This location provides a protected place where the device won&#39;t interfere with heart and lung movement.  
      The proximal ends of the leads are then secured to the device and the entrance wound is closed. The lengths of the leads vary based on the size of the patient. It is undesirable to have leads that are somewhat taught because the chances of them becoming dislodged are increased. However, leads that are too long are also undesirable because due to lead losses inherent in all electrical leads. Furthermore, excessive length can result in migration of the leads to areas where they become affected by moving organs, etc. If the attending physician determines that the leads are too short after attaching the distal ends thereof to the organ, the physician must presently remove the leads and replace them with longer leads, thereby extending the procedure and significantly increasing the risks associated therewith.  
      Though the occurrence of a situation where it is determined that longer leads are required can be minimized through careful planning, reality dictates that such instances are never eliminated. Problems may arise despite careful planning that require the relocation of an implantable device, either upon initial placement of during a follow-up procedure. There is thus a need for a device that allows the lengthening of leads after the distal ends thereof have been attached to a recipient organ.  
     BRIEF SUMMARY OF THE INVENTION  
      The present invention is directed to fulfilling the identified need by providing a lead system whereby lead extension may be attached to a proximal end of the lead of an insertable device that has already been attached to a recipient organ. The present invention includes an attachment mechanism and lead extensions of various lengths such that an optimal lead length can be achieved even after leads have been attached to the target organ. The lead extensions are useful during initial implantation of the device and during subsequent device relocation procedures.  
      The present invention includes a lead extension which has connectors on its ends which are configured to mate with the existing lead and the implantable device. In this way, the attending physician can simply attach the extension to the lead, thus extending the overall distance between an installed electrode and the implantable device. As clearly anticipated, this is much more desirable than removing the attached electrode so that a longer lead can be used.  
      The connectors on the extension also include sufficient features to provide a secure attachment. This may include a snap fit structure, or may include set screws, to ensure that the connection is solidly made. Further, an insulating covering is provided which can cover the connecting elements and providing further protection. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a perspective view of an embodiment of the system of the present invention; and,  
       FIG. 2  is a perspective view of an embodiment of a lead extension of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      Referring now to the Figures, there is a shown a system  10  of the present invention. The system includes an implantable device  12 , a lead  14  for attachment to a recipient organ, and a lead extension  16  for placement between the device  12  and the lead  14 , thereby effectively increasing the length of the lead  14   
      The implantable device  12  may be any implantable device using leads. The most commonly recognized implantable devices include pacemakers and defibrillators. The device includes at least one male or female connector  18 , to which a lead  14  or extension  16  may be attached. For purposes of discussion, an implantable cardioverter defibrillator will be used as an example of an implantable device  12 .  
      The leads  14  include a distal end  20 , for attachment to the recipient organ, in this example the heart (not shown). Opposite the distal end  20  is a proximal end  22 . The proximal end  22  includes a female or male connector  24 , attachable to the male or female (respectively) connector  18  of the device  12 . The example shown in  FIG. 1  includes a device  12  having standard female connectors  18 , into which leads  14  having standard male connectors  24  at their proximal ends  22  may be plugged.  
      The lead extensions  16  of the present invention are constructed and arranged such that a lead  14  may be unplugged from a device  12  and a lead extension  16  may be placed between the device  12  and the lead  14 . Thus, the lead extension  16  includes a proximal end  26  and a distal end  28 . The proximal end  26  includes a connector  30  capable of being connected with a connector  18  of the device  12 . In the example of  FIG. 1 , and shown in greater detail in  FIG. 2 , the connector  30  at the proximal end  26  of the lead extension  16  is a male connector that is physically similar, if not identical, to the connector  24  of the lead  14 . The distal end  28  includes a connector  32  that is configured to mate with the connector  24  at the proximal end  22  of the lead  14 . Preferably, the connector  32  includes a securing device  34 , such as setscrews, a snap connector, or the like, to prevent unintentional disconnection from the lead  14 .  
      The lead extension  16  may be of any length but it is envisioned that extensions are provided in various incremental lengths such as 5 cm, 10 cm, 15 cm, etc. As another feature of the present invention extension  16  is covered in a sleeve  36  having rolled ends  38  that can be unrolled after installation to cover the connectors. The sleeve  36  may be constructed of the same material as that used to cover the leads  14 . This rolled end structure  38  provides the ability to insulate and protect the connection between leads  14  and extension  16  when implemented. This obviously provides protection to the connection and insures that undesired signals are not transmitted to other parts of the body.  
      In order to provide more convenience to the physician, the extensions may be provided as a kit. More specifically, the kit may include a number of extensions of varying length. Thus, during procedures, the physician would have the opportunity to simply select the extension that best fits the particular needs of the patent.  
      It is contemplated that features disclosed in this application can be mixed and matched to suit particular circumstances. Various other modifications and changes will be apparent to those of ordinary skill in the art without departing from the spirit and scope of the present invention. Accordingly, reference should be made to the claims to determine the scope of the present invention.