Abstract:
An implantable medical device that includes a header a cavity or connector bore that extends from an opening at a first end of the header towards a second end of the header. The cavity is configured to receive a first end of a stimulation lead. The header includes a lead insertion indicator positioned at the second end of the cavity for engaging with the stimulation upon complete insertion into the header. The lead insertion indicator is operable between a first operating state and a second operating state, such that when the stimulation lead is not engaged with the lead insertion indicator, the lead insertion indicator operates in the first operating state, and when the stimulation lead properly engages the lead insertion indicator, the lead insertion indicator operates in the second operating state. The lead insertion indicator generates a signal that indicates the corresponding operating state.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to medical devices having leads associated therewith, and more particularly, but not by way of limitation, to a device and method for providing verification of proper lead insertion into either the header or connector of an implantable medical device. 
       BACKGROUND 
       [0002]    Numerous medical devices have been developed and used from providing various types of therapy to patients. Some of the medical devices utilize electrical leads for delivering therapy and/or monitoring various physiological conditions of the patient. The electrical lead carries sensors or electrodes for deployment to the targeted therapy delivery or monitoring site. For example, implantable electrical leads are commonly used to form part of implantable neurostimulation systems in which a pulse generator and electrical leads are implanted in a patient to provide pain management through controlled electro-stimulation via electrodes disposed on the electrical leads, typically near the distal ends of the leads. 
         [0003]    The electrodes are coupled to conductors extending to the proximal end of the electrical lead where each conductor is coupled to a connector included in a lead connector assembly. The pulse generator is generally provided with a connector header having cavities adapted for receiving a corresponding lead connector assembly. The connector cavities have electrical contacts which mate with the connectors included on the lead connector assembly. When the lead connector assembly is properly inserted in the connector cavity, the electrodes carried by the electrical lead are electrically coupled to the circuitry contained in the pulse generator via feedthroughs which connect the connector header contacts to the circuitry contained in the pulse generator. Thus, proper insertion of the lead connector assembly into the connector cavity is essential for proper operation and therapy delivery of the of neurostimulation system. 
         [0004]    Some implantable device systems utilize a visual lead insertion indicator for the verification of proper electrical lead insertion. For example, some implantable device systems utilize a visibly modified surface on the electrical lead to facilitate visual verification of full insertion into the connector cavity of the header. A disadvantage of the visual indicator is that it provides no benefit once the device has been implanted into the patient. Because the visual indicators can no longer be seen after being implanted, if a lead pulls at least partially out of the connector cavity, an x-ray or explant would be needed to verify this. 
         [0005]    It would be advantageous to have a system and method for ensuring and verifying the proper and continuous insertion of a lead into the header of an implantable medical device that overcomes the disadvantages of the prior art. The present invention provides such a system and method. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         [0006]    In the following section, the invention will be described with reference to exemplary embodiments illustrated in the figures, in which: 
           [0007]      FIG. 1  illustrates one embodiment of an implantable stimulation system which may utilize certain aspects of the present invention; 
           [0008]      FIG. 2  is block diagram of a stimulation system which may utilize certain aspects of the present invention; 
           [0009]      FIG. 3  is a cross-sectional view of a header as similarly shown in  FIG. 1 ; 
           [0010]      FIG. 4  illustrates a portion of the cavity of a header and lead insert indicator of a header for receiving a lead which may utilize certain aspects of the present invention; 
           [0011]      FIG. 5  illustrates the portion of the cavity illustrated in  FIG. 4  with a lead inserted therein and engaging the lead insert indicator; 
           [0012]      FIG. 6  illustrates a dual lead insert indicator which may be utilized in certain configurations of headers for receiving two leads; 
           [0013]      FIG. 7  illustrates another embodiment of a portion of cavity of a header and lead insert indicator of the header for receiving a lead which may utilize certain aspects of the present invention; and 
           [0014]      FIG. 8  illustrates the a portion of a cavity as similarly illustrated in  FIG. 7  with a lead inserted and engaging the lead insert indicator. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    For the purposes of promoting an understanding of the principles of the present invention, reference will now be made to the embodiments, or examples, illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Any alterations and further modifications in the described embodiments, and any further applications of the principles of the inventions as described herein are contemplated as would normally occur to one skilled in the art to which the invention relates. 
         [0016]    When directions, such as upper, lower, top, bottom, clockwise, counter-clockwise, are discussed in this disclosure, such directions are meant to only supply reference directions for the illustrated figures and for orientations of components in the figures. The directions should not be read to imply actual directions used in any resulting invention or actual use. Under no circumstances, should such directions be read to limit or impart any meaning into the claims. 
         [0017]    Referring now to  FIG. 1 , there is illustrated an exemplary implantable stimulation system  100  which may employ certain aspects of the present invention. Stimulation system  100  includes a stimulation source, such as an implantable pulse generator  110  (“IPG”) which may be coupled to one or more stimulation leads  112  and  114 . As will be explained below, the IPG  110  typically includes a power source (such as a battery) and electronics (such as hardware, software, or embedded logic components) for generating electrical stimulation signals or pulses. 
         [0018]    In this example, the stimulation system  100  employs the two stimulation leads  112  and  114  inserted into and connected to the header  116  of IPG  110 , but any number of stimulation leads could be employed and are within the scope of the present invention. Each of the leads  112  and  114  may generally be configured to transmit one or more electrical signals from the IPG  110  to a spinal nerve, a peripheral nerve, or other tissue. As illustrated in  FIG. 1  by the break lines, the leads  112  and  114  are not meant to accurately represent the actual length of the leads relative to the pulse generator. Header  116  utilizes set-screws  117  to engage and mechanically secure leads  112  and  114  to substantially inhibit the removal of leads  112  and  114  from header  116  (see  FIGS. 4 and 5 ). 
         [0019]    Each of the leads  112  and  114  include a proximal end  106  and a distal end  108  and comprises a flexible lead body that extends from proximal end  106  to the distal end  108 . In certain embodiments, one or more lumens (not shown) may extend through leads  112  and  114  and may be used for housing one or more stiffeners (not shown). 
         [0020]    In certain embodiments, each of the leads  112  and  114  may be a structure having a round or substantially round cross-section. Alternatively, the cross-section of each of the leads  112  and  114  may be configured in any number of cross-sectional shapes appropriate for a specific application in which the lead will be used. Depending on the particular application, the diameter of the lead may be any size, though a smaller size is more desirable for lead applications such as neurological and myocardial mapping/ablation and neuromodulation and stimulation. 
         [0021]    The leads  112  and  114  may each be formed of an extrusion or insulating material typically selected based upon biocompatibility, biostability and durability for the particular application. The insulator material may be silicone, polyurethane, polyethylene, polyamide, polyvinylchloride, PTFT, EFTE, or other suitable materials known to those skilled in the art. Alloys or blends of these materials may also be formulated to help control the relative flexibility, torqueability, and pushability of the lead. In some applications, compliant material characteristic enables the each of the leads  112  and  114  to elongate significant amounts at relatively low stretching forces. 
         [0022]    Adjacent to the distal end  108  of each of the leads  112  and  114  is a stimulation electrode region  118  comprising, in this embodiment, a plurality of eight stimulation electrodes  120  on each of the leads  112  and  114 . Each of the leads  112  and  114 , at proximal end  106 , comprises a corresponding plurality of eight connector or terminal electrodes  121  sized to couple with the header  116  (See  FIG. 3 ). As will be appreciated by those skilled in the art, any number of corresponding conductors and electrodes may be utilized at the two ends of leads  112  and  114 . 
         [0023]    In certain embodiments, the electrodes may be formed of biocompatible, conductive materials such as stainless steel, platinum, gold, silver, platinum-iridium, stainless steel, MS35N, or other conductive materials, metals or alloys known to those skilled in the art. In some embodiments, the electrodes may be ring or cylindrical electrodes which encircle ends  106  and  108  of leads  112  and  114 . Other types, configurations and shapes of electrodes as known to those skilled in the art may be used with embodiments. 
         [0024]    One or more conductors (not shown) extend along a substantial portion of each of the leads  112  and  114  to electrically connect the corresponding electrodes between ends  106  and  108 . The one or more conductors of lead  112  and  114  may be maintained in electrical isolation by insulative material of each of the leads  112  and  114 . 
         [0025]    In certain embodiments, the conductors may be formed of a conductive material having desirable characteristics such as biocompatibility, corrosion resistance, flexibility, strength, low resistance, etc. The conductors may take the form of solid wires, drawn-filled-tube (DFT), drawn-brazed-strand (DBS), stranded wires or cables, ribbon conductors, or other forms known or recognized to those skilled in the art. The composition of the conductors may include aluminum, stainless steel, MP35N, platinum, gold, silver, copper, vanadium, alloys, or other conductive materials or metals known to those of ordinary skill in the art. In some embodiments, the number, size, and composition of the conductors will depend on the particular application for the lead, as well as the number of electrodes. 
         [0026]    The IPG  110  includes a housing  122  to enclose elements (described herein below) for generating the electrical pulses for application to neural tissue of the patient. The elements enclosed in the IPG housing  122  may include control circuitry having one or more microprocessors and recharging circuitry, pulse generating circuitry, communication circuitry, and a power source for the device. 
         [0027]    The IPG  110  is usually implanted within a subcutaneous pocket created under the skin by a physician. The leads  112  and  114  are typically mechanically and electrically coupled to the IPG  110  and thus may be used to conduct the electrical pulses from the implant site of the IPG  110  to the targeted nerve tissue via a plurality of stimulation electrodes  120 . For example, the stimulation electrode region  118  of leads  112  and  114  may be positioned within the epidural space of the patient to deliver electrical stimulation to spinal nerves to treat chronic pain of the patient. 
         [0028]    Referring now to  FIG. 2 , there is illustrated a block diagram of a stimulation system  200  having an implantable pulse generator (IPG)  210  and leads  212 , and an external communication/charger  224 . The IPG  210  includes power circuitry  214 , header  216 , pulse generator  218 , controller  220  and communication circuitry  222 . The external communication/charger  224  communicates with the communications circuitry  222  of IPG  210  via a wireless communication link and provides functionality and control mechanism to program the operating parameters of the IPG  210 . The external communication/charger  224  also transmits a charging signal that is received by IPG  210  via a wireless link and is utilized to recharge rechargeable power source  214  within IPG  210 . Header  216  electrically and mechanically connects leads  212  to IPG  210 . Controller  220  includes one or more microprocessors and recharging circuitry. Controller  220 , power circuitry  214  and pulse generator  218  function to program, control and generate electrical stimulation signals delivered to leads  212 . 
         [0029]    Referring now to  FIG. 3 , there is illustrated a sectional view of header  116  as similarly shown in  FIG. 1 . Header  116  includes a generally elongated body  117  and is preferably adapted to receive ends of lead leads  112  and  114 , and to provide electrical interfacing between the leads and IPG  110 . Accordingly, header  116  of the illustrated embodiment includes cavities  310  and  312 , disposed in substantial alignment with electrodes  121  of a corresponding leads  112  and  114  when fully inserted, into which electrical contact assemblies  320  may be disposed. For example, spring biased contact assemblies  320  may be disposed in each of cavities  310  and  312  to provide electrical contact with corresponding electrodes  121  of leads  112  and  114  when inserted into header  116 . The contact assemblies  320  are coupled to the circuitry housed within housing  122  of IPG  112  via feedthroughs (not shown). The foregoing electrical contact assemblies preferably allow insertion of a lead end through the cavities of header during installation while providing a reliable electrical contact when the leads are fully inserted into the header. It is contemplated that header  116  could include a locking mechanism to securely hold the leads therein when fully inserted. An example of a locking mechanism that can be utilized in header  116  is a set-screw assembly (see  FIGS. 4 and 5 ). This provides a mechanical holding force to inhibit an undesired removal of the leads from the header  116 . 
         [0030]    As illustrated in  FIG. 3 , header  116  includes lead insertion indicators  330  and  332 , each being positioned at the end of connector bores or cavities  310  and  322 , respectively. Lead insertion indicators  330  and  332  are configured to be operable between at least two operating states, such that when a lead properly engages a respective lead insertion indicator, a detectable change in state of the lead insertion indicator occurs when the lead insertion indicator changes between the first state and the second state, indicating proper insertion and continued insertion of the lead into the cavity. As can be appreciated, the lead insertion indicators  330  and  332  could be mounted within header  116  using various mounting techniques. 
         [0031]    Referring now to  FIGS. 4 and 5 , there is illustrated an embodiment of a lead insertion indicator  400  utilized in the present invention. In this particular embodiment, lead insertion indicator  400  includes a pressure or micro-force sensor  410  mounted a printed circuit board (“PCB”)  411 , both of which are mounted to or secured to a set-screw block  412 . For illustration clarity, set-screw block  412  is shown rotated so that the set-screw does not block the illustration of the other elements. The sensor  410  and PCB  411  can be mounted to set-screw block  412  utilizing a variety mounting techniques, such as, but not limited to, the use of mechanical fasteners or chemical fasteners, such as adhesives. Set-screw block  412  with PCB  411  and sensor  410  are inserted into the end of cavity of the header, whereby a connection wire (not shown), from sensor  410  is electrically connected to a feedthrough wire (not shown) for electrical connection between sensor  410  and the circuitry in the IPG. 
         [0032]    In operation, as illustrated in  FIG. 4 , prior to the insertion of lead, such as by way of example lead  114  of  FIGS. 1 and 3 , into set-screw block  412 , sensor  410  is in a first position or state. Upon the proper full insertion of lead  114  into the header and into set-screw-block  412 , the end of lead  114  engages sensor  410 , causing sensor to change from the first operating state to a second operating state. By way of example, if sensor  410  were a piezoresistor force sensor, in the first operating state when the lead is not in contact with sensor  410 , force sensor would have a first resistive value and have a corresponding output indicative of the first operating state. When the end of lead  114  comes into contact with sensor  410  changing the sensor, the resistance of the force sensor changes when flexed under the applied force of the lead, thereby having a second resistive value and a corresponding output indicative of the second operating state. Similarly, when lead  114  is removed far enough from set-screw block  412  so as to disengage sensor  410 , the force sensors changes from the second operating state back to the first operating state. 
         [0033]    The output of sensor  410  indicating either of the operating states of sensor  410  is communicated to the IPG. The IPG can communicate information corresponding to the operating state of sensor  410  to the external communication/charger  224  such that a user can check, based upon the indication of the operating state of sensor  410 , whether the lead is properly inserted into the header and engaging sensor  410 . This enables a user to check the status of the proper insertion of the lead into the header prior to the implantation of the IPG into the patient, and if needed, to be able to check the continued proper insertion of the lead into the header subsequent to implantation of the IPG into the patient without any surgical procedures, such as the removal the IPG from the patient to check the status of the lead. 
         [0034]    Referring now to  FIG. 6 , there is illustrated an alternative embodiment of the use of the micro-force sensor  410  as similarly shown in  FIGS. 4 and 5 . As illustrated, two micro-force sensors  410   a  and  410   b  are mounted to a single PCB  411   a , which would be mounted to or secured to set-screw blocks with each of the micro-force sensors  410   a  and  410   b  in a separate set-screw block. The sensors  410   a  and  410   b  and PCB  411   a  can be mounted to set-screw blocks utilizing a variety mounting techniques, such as, but not limited to, the use of mechanical fasteners or chemical fasteners, such as adhesives. PCB  411   a  and sensors  410   a  and  410   b , subsequent to their attachment to set-screw blocks would be inserted into the end of cavity of a header with each of the sensors  410   a  and  410   b  setup in alignment with two adjacent cavities for receiving leads, whereby a connection wire (not shown), from the sensors  410   a  and  410   b  would be electrically connected to feedthrough wires (not shown) for electrical connection between sensors  410   a  and  410   b  and the circuitry in the IPG. 
         [0035]    In operation, as similarly described with reference to the embodiments of  FIGS. 4 and 5 , prior to the insertion of leads into a header, each of the sensors  410   a  and  410   b  would be in a first position or state. Upon the proper full insertion of leads into the header and into corresponding set-screw blocks, the ends of the leads would engage the sensors  410   a  and  410   b , causing corresponding sensors to change from the first operating state to a second operating state. By way of example, if sensors  410   a  and  410   b  were piezoresistor force sensors in the first operating state when the leads were not in contact with sensors  410   a  and  410   b , each sensor would have a first resistive value and have a corresponding output indicative of the first operating state of that sensor. When the end of leads come into contact with each of sensors  410   a  and  410   b , the resistance of the sensors change when flexed under the applied forces of the leads, thereby having second resistive values and corresponding outputs indicative of the second operating state of each of the sensors. 
         [0036]    The output of sensors  410   a  and  410   b  indicating either of the operating states of the sensors are communicated to the IPG. The IPG can communicate information corresponding to these operating states to the external communication/charger  224  such that a user can check, based upon the indication of the operating state of sensor  410 , whether the lead is properly inserted into the header and engaging sensor  410 . This enables a user to check the status of the proper insertion of the lead into the header prior to the implantation of the IPG into the patient, and if needed, to be able to check the continued proper insertion of the lead into the header subsequent to implantation of the IPG into the patient without any surgical procedures, such as the removal the IPG from the patient to check the status of the lead. 
         [0037]    Referring now to  FIGS. 7 and 8 , there is illustrated another embodiment of a lead insertion indicator utilized in the present invention. In this particular embodiment, lead insertion indicator includes a lever switch  710  mounted to a printed circuit board (“PCB”)  411 , both of which are mounted to mount or block  712 . The switch  710  and PCB  411  can be mounted to block  712  utilizing a variety mounting techniques, such as, but not limited to, the use of mechanical fasteners or chemical fasteners, such as adhesives. Block  712  with PCB  411  and switch  710  are inserted into the end of cavity of the header, whereby a connection wire (not shown), from switch  710  is electrically connected to a feedthrough wire (not shown) for electrical connection between switch  710  and the circuitry in the IPG. 
         [0038]    In operation, as illustrated in  FIG. 7 , prior to the insertion of lead, such as by way of example lead  114  of  FIGS. 1 and 3 , block  712 , switch  710  is in an open or first position or state. Upon the proper full insertion of lead  114  into the header and into block  712 , the end of lead  114  engages switch  710 , causing switch  710  to change from an open state to a closed state, or from a first operating state to a second operating state. 
         [0039]    The IPG, being electrically connected to switch  710 , can communicate information corresponding to the operating state of switch  710  to the external communication/charger  224  such that a user can check, based upon the indication of the operating state of switch  710 , whether the lead is properly inserted into the header and engaging switch  710 . This enables a user to check the status of the proper insertion of the lead into the header prior to the implantation of the IPG into the patient, and if needed, to be able to check the continued proper insertion of the lead into the header subsequent to implantation of the IPG into the patient without any surgical procedures, such as the removal the IPG from the patient to check the status of the lead. 
         [0040]    Although the present invention is described herein to being disposed in the header of an IPG, it is contemplated to be within the scope of the invention that the present invention could also be incorporated into other implantable devices, such as but not limited to, the connector portions of lead extenders and the like. 
         [0041]    As will be recognized by those skilled in the art, the innovative concepts described in the present application can be modified and varied over a wide range of applications. Accordingly, the scope of patented subject matter should not be limited to any of the specific exemplary teachings discussed above, but is instead defined by the following claims.