Patent Publication Number: US-9420962-B2

Title: Remote lead implant testing

Description:
TECHNICAL FIELD 
     The present disclosure generally relates to implantable medical devices. More specifically and without limitation, the present disclosure relates to leads for implantable medical devices. 
     CROSS REFERENCE TO RELATED APPLICATION 
     Reference is made to commonly-assigned and co-pending application U.S. Ser. No. 12/112,111, filed Apr. 30, 2008, entitled “Lead Implant System;” U.S. Ser. No. 12/112,095, filed Apr. 30, 2008, entitled “Lead-Implant Coupling Device;” and U.S. Ser. No. 12/112,090, filed Apr. 30, 2008, entitled “Medical Device Packaging Systems Including Electrical Interfaces,” all of which are herein incorporated by reference in their entirety. 
     BACKGROUND 
     In general, implantable medical devices are commonly used with medical electrical leads. Medical leads deliver electrical energy for stimulation of tissue, receive sensed electrical impulses from tissue, or transfer other sensory data indicative of a physical parameter. For example, implantable cardiac pacemakers, cardioverters, or defibrillators commonly have one or more leads connecting the device to cardiac tissue. The leads are typically inserted through a vein and guided into the target location of the cardiac tissue. Once so located, the distal end of the lead is typically affixed to the tissue to secure the lead in the desired location. 
     Maintaining a sterile field around the incision site is especially important during the implantation procedure. The sterile field prevents contamination that may otherwise occur due to unsanitary conditions. Contamination of the surgical incision site during the implant procedure can lead to pocket infection (infection of the incision site) which may propagate to the cardiac tissue. Therefore, numerous steps are taken during the implant procedure to minimize or prevent the risk of contamination of the surgical incision site. In addition to providing a sterile field around the incision site, all the instruments, tools and equipment that come in contact with the sterile field during the implant procedure are sterilized prior to use and re-sterilized if any contamination is suspected. 
     Generally, the lead implant procedure may be thought of as a two-phase process. The first involves the placement of the lead in the target tissue while the second phase involves verification of the implanted lead&#39;s functionality and determining whether the placement location is appropriate or if there is a need to reposition the lead. This verification is typically performed though testing performed via a programmer. The programmer used can be a fully functional programmer, such as MEDTRONIC MODEL 9790 ®, or a task specific programmer, such as a pacing system analyzer. In the first phase, a lead is passed through a vein into the desired tissue location and secured to the tissue. Following the placement of the distal end of the lead in the target tissue, a programmer is attached to the proximal end of the lead and various parameters are checked to verify the functionality and whether the lead implant location is appropriate. Thereafter the implantable medical device is connected to the lead and the incision site is closed thereby sealing the implantable medical device and lead within the patient&#39;s body. 
     As the foregoing discussion of the implant procedure demonstrates, the need to re-position the distal end of the lead is typically discovered during the second phase and after much time has been expended placing the lead in the first phase. Moreover, the programmer is located outside the sterile field and is connected to the leads using a set of cables. 
     The programmer cables therefore have to be sterilized and care taken to ensure that they remain within the sterile field during the implant procedure to prevent contamination of the incision site. Furthermore, the process of re-positioning the lead to an optimal location requires that the programmer cable be disconnected from the lead to allow for the lead to be navigated to the new location in the tissue. As such, many implant procedures may be cumbersome and time consuming. 
     BRIEF SUMMARY OF DISCLOSURE 
     The illustrative implementations of the present disclosure include lead coupling devices having electrical connectivity to a lead so as to facilitate improved implant procedure speed and reduce the risk of infection. 
     In one embodiment a pulse generator, a power source, and electrical contacts are integrated into a housing assembly to provide a lead coupling device. The device includes a channel which is adapted to receive a lead. Further, the electrical contacts are disposed on the exterior surface of the channel of the device to provide electrical connectivity between the lead and the device. 
     In another embodiment the lead coupling device further includes a wireless communication module that provides wireless communication between the device and an external device. The device eliminates the need for a physical wired connection between the lead and the external device while enabling real time measurements to be performed through the lead during the implant procedure. 
     In yet another embodiment, a display is coupled to the lead coupling device to provide an indication of a parameter sensed through the lead. The sensed parameter in one embodiment is the impedance of tissue adjacent to the lead. 
     In another embodiment, a lead coupling device includes means for engaging a proximal end of a lead, means for electrically coupling the lead, and means for receiving a signal sensed by the lead. 
     In another embodiment, a method of implanting a lead comprises connecting a lead to a lead coupling device such that the lead may be maneuvered during implantation, providing electrical energy to the lead and receiving a sensed signal from the lead. 
     The foregoing summary is intended to briefly introduce the reader to the basic concepts of the present disclosure and should not be construed as limiting. The details of one or more embodiments are set forth in the accompanying drawings and the description below. In the drawings, like numerals are used to denote identical elements. Other features, objects, and advantages of these embodiments will be apparent from the description and drawings, and from the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic overview of a system with a coupling device coupled to an electrical lead for an implant procedure. 
         FIG. 2  is a side sectional view of the coupling device coupled to an electrical lead. 
         FIG. 3  is a side sectional view of the coupling device including electrical contacts. 
         FIG. 4  is a functional block diagram illustrating various constituent electrical components of a coupling device. 
         FIG. 5  depicts a side sectional view of an alternative coupling device. 
         FIGS. 6A and 6B  are functional flowcharts of the operation of the coupling devices of  FIGS. 2 and 5 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a schematic overview of exemplary system  1  which depicts a sterile field  2  and a non-sterile field  3  during an implant procedure of medical electrical lead  12  into a patient  10 . Ordinarily, an electrical connector assembly disposed on lead  12  is coupled to a programmer  30  through a programmer cable (not shown) that extends from the non-sterile field  3  to the sterile field  2 . Consequentially, encroachment of the sterile field  2  occurs every time the cables are clipped on and off the lead  12  during the implant procedure. 
     In order to reduce contamination of the sterile field  2 , a lead coupling device  100  that couples directly to the lead  12  is provided. In one embodiment, the coupling device  100  incorporates a wireless communication protocol that enables communication with external devices such as the programmer  30 . With the wireless communication capability, the coupling device  100  may remain connected to the lead  12  during the entire implant procedure while permitting any desired communication with programmer  30  located outside the sterile field  2 . 
       FIG. 2  is a side sectional view of a coupling device  100  coupled to lead  12 . The lead  12  includes a connector pin  14  at a proximal end  13  of lead  12  and an opening (not shown) that extends to lumen  15 . It may be noted that the lead  12  is merely exemplary, and many other lead configurations may be employed with the present disclosure. The coupling device  100  includes a housing  106  with electronic components ( FIG. 4 ) disposed within the housing  106 . The housing  106  can be fabricated from any suitable material, including plastic or metal, that can be properly sterilized for use in a surgical field. In an exemplary embodiment, housing  106  is formed from a molding fabrication process. The molding process includes mounting the electronic components on an inner layer  101  of a plastic material and subsequently coating the electronics through an overmold process. Alternatively, the housing  106  may be formed with an electronics component chamber  102 , having a cover  103  that provides access to the electronic components. 
     The outer surface of housing  106  may include a gripping or textured surface (e.g., ridges) to facilitate handling of the coupling device  100 . In alternate embodiments, a sleeve  800  may be provided for placement over the housing  106  to facilitate gripping. 
     A lead channel  108  is disposed within the housing  106  to receive the proximal portion  13  of lead  12 . The lead channel  108  extends from a distal opening  107  to a proximal opening  105  and guides the lead  12  toward the proximal end of the coupling device  100 . In one embodiment, the size of the proximal opening  105  and distal opening  107  is selected to be larger than the diameter of lead  12 . 
     In some embodiments, a guide tool  18 , such as a stylet or a guidewire, designed to facilitate maneuvering of the lead  12  is inserted through the lumen  15 . The tool  18  provides additional rigidity to lead  12  and facilitates navigation. However, due to the small diameter of certain of the lead  12  configurations, the lumen is similarly small. To facilitate the insertion of the tool  18  into the lumen  15 , the distal opening  107  is provided with a tapered portion  16 . The tapered portion  16  provides an enlarged opening that facilitates the insertion of tool  18  into the lumen  15 . 
     An optional lead engagement mechanism  112  may be provided to facilitate gripping of the lead  12 . Functionally, the engagement mechanism acts to grip the body of lead  12  so that torque can be applied to the lead  12  by rotating the coupling device  100 . Alternatively, the lead channel  108  alone, or in combination with the engagement mechanism  112  can be configured to grip the lead  12  through a frictional fit. As used herein, gripping includes but is not limited to clamping, squeezing, locking, sliding, compressing, screwing, twisting, snapping, interlocking, or otherwise causing appropriate engagement between the lead  12  and the coupling device  100 . 
     In the embodiment illustrated in  FIG. 2 , engagement mechanism  112  is a resilient member having a C-shaped clamp  114  affixed to a base  116  and medially disposed within the lead channel  108 . The clamp  114  is resilient or spring biased so that insertion of the lead  12  causes the clamp  114  to expand and generate an interference fit. Alternatively, other shapes, prong or clamp configurations could be employed. The C-shaped clamp  114  or equivalent interference fit arrangements do not require additional actions to be taken by the implanting physician beyond insertion of the lead  12  into the coupling device  100 . Alternative active clamping mechanisms may be used that provide additional gripping force, but do require additional steps in their use along with additional components. The particular configuration selected will depend upon the leads being implanted and the active fixation requirements of those leads. 
     In general, the force required to insert the lead  12  into the lead channel  108  will depend upon the mechanism employed to grip the lead  12 . For example, the resilient clamp  114  will require sufficient force to overcome the spring tension or resiliency of the clamp  114 . A lead channel  108  providing a frictional lock will require sufficient force to overcome the frictional forces. With an active external clamping mechanism, seating the lead  12  would require little applied force, as the gripping force is selectively applied after insertion. Nonetheless, it is desirable for the lead  12  to be insertable into the lead channel  108  with as minimal force as possible. By way of example, but not limitation, the mechanism employed may be configured such that only a minimal force ranging from 1.5 lbs to 2.5 lbs would be required to insert the lead  12  into the lead channel  108 . 
     As illustrated in  FIG. 3 , electrical contacts  122 ,  124  are positioned in the lead channel  108  such that a portion of their conducting surface is exposed. The exposed portions of electrical contacts  122 ,  124  are configured to engage the electrical connector assembly (not shown) of the lead  108 . In one embodiment, the two-contact electrical arrangement electrically and mechanically couples the coupling device  100  to lead  12  having an IS-1 standard connector assembly. In alternate embodiments of the present disclosure, additional electrical contacts may be provided on coupling device  100  so as to correspond to any other connector assembly standard that is used for lead  12 . For instance, coupling device  100  is provided with an electrical contact arrangement that corresponds to a DF-1 connector standard, or a four contact arrangement to couple lead  12  with a connector assembly conforming to an IS-4 connector standard. 
     The contacts  122 ,  124  are coupled to the electrical circuitry ( FIG. 4 ) disposed within the housing  106 . In the illustrated embodiment, the contacts  122 ,  124  are formed as spring contacts. However, the electrical contacts  122 ,  124  could take other forms such as a set screw rotated from the outer surface  104  to engage the lead connector assembly (not shown). To facilitate electrical conduction between the lead  12  and the coupling device  100 , the electrical contacts  122 ,  124  are formed from a noble material such as platinum or gold. 
       FIG. 4  is a functional block diagram illustrating various electrical components of the coupling device  100  that includes a microprocessor-based architecture. The electrical contacts  122 ,  124  are functionally coupled to a pulse generator  196  via node  140 . Pulse generator  196  is coupled to microcomputer circuit  162  which is used to control and/or monitor generation of electrical energy by the pulse generator  196  using software-implemented algorithms stored therein. Microcomputer circuit  162  comprises on-board circuit  164  and off-board circuit  166 . On-board circuit  164  includes microprocessor  165 , system clock circuit  168  and on-board RAM  170  and ROM  172 . Off-board circuit  166  comprises a RAM/ROM unit. A multiplexer unit  184  is optionally coupled to microcomputer  162  to allow selectivity of anode and cathode arrangements of the electrical connector on lead  12 . 
     Electrical energy generated by the pulse generator  196  is transmitted through node  140  and this energy is provided to the lead  12  through electrical contacts  122 ,  124 . In one embodiment, microcomputer circuit  162  controls the amplitude and duration of the electrical energy generated by the pulse generator  196 . 
     Continuing to refer to  FIG. 4 , sensing circuitry  186  is coupled to the microcomputer circuit  162  to receive one or more signals that is sensed via a sensor (not shown) or electrode (not shown) on lead  12 . The sensed signals are transmitted through the lead  12  and provided to the coupling device  100  through electrical contacts  122 ,  124 . The sensed signal received at electrical contacts  122 ,  124  is transmitted through node  140  and provided to the sensing circuitry  186 . The microcomputer circuit  162  includes software-implemented algorithms to control the sensing operation of the coupling device  100 . The sensed signals received by the sensing circuitry  186  include, for example, physiological signal such as impedance, voltage, current, temperature, heart rate, blood pressure, electromyography, electro-encephalography, and electro-oculography. 
     In additional embodiments, coupling device  100  is configured for wireless communication with an external programming unit  30  ( FIG. 1 ). Therefore, a wireless communication module  180  is coupled to the microcomputer circuit  162  to provide the wireless communication. Any of a number of suitable programming and wireless communication protocols known in the art may be employed so long as the desired information is transmitted to and from the coupling device  100 . In alternative embodiments of the present disclosure, other communication protocols such as Bluetooth® communication, IEEE 802.11, Home RF or other short- and long-range wireless protocols may be employed as the wireless communication technique. 
     The external programming unit  30  ( FIG. 1 ) may be used in conjunction with or as a substitute to the software implemented algorithms in microcomputer circuit  162  to control the operation of coupling device  100 . In other words, the pulse generator  196  provides electrical energy to lead  12  based on a command received from the microcomputer  162  or a command sent from external programming unit  30 . Similarly, the sensing operation by sensing circuitry  186  may be initiated by the microcomputer  162  or the external programming unit  30 . Further, the wireless communication module  180  provides wireless transfer of sensed data received by the coupling device  100  to the external programming unit  30 . It is generally preferred that the particular programming and communication protocol selected permit the entry and storage of multiple physiological parameters. However, in some embodiments of the present disclosure, the protocol chosen could be a “repeating” protocol where the sensed parameters are merely relayed to the programming unit  30  ( FIG. 1 ) without the need for storage. 
     In some embodiments, security features are incorporated into the wireless communication protocol utilized to prevent cross-talk between various devices. Exemplary embodiments of the security features of the present disclosure could include algorithms within the programmer  30  or the coupling device  100  that initiate a communication session. The algorithms incorporate unique device identification of the coupling device  100 . Thus prior to initiating the communication session between the programmer  30  and the coupling device  100 , the identity of the coupling device  100  is authenticated by the programmer  30 . Other security features known in the art may be utilized for the security function. 
     The electrical components shown in  FIG. 4  are powered by a battery power source  178  in accordance with common practice in the art. Such a power source could either be rechargeable or non-rechargeable. 
     As discussed above, implantable lead  12  varies in construction, size, and design depending on the model of the lead  12 . In addition to the variations noted, some of the available leads  12  include a helical coil (not shown) at the distal tip of the lead  12 . This helical coil is typically rotated into the target tissue to affix the lead  12  into the tissue. The helical coil is coupled to a conductor that extends from the distal end (not shown) to the proximal end  13  of the lead  12  and terminates at a pin  14 . Subsequent to implantation of the lead  12 , pin  14  is coupled to an electrical connector of a medical device (not shown) to be implanted in the patient  10 . The implantation procedure of lead  12  having a helical coil therefore requires the rotation of the pin  14  which causes rotation of the helical coil in order to secure the helical coil into the target tissue. 
     Turning now to  FIG. 5 , an alternative embodiment of the coupling device of  FIG. 2  is depicted. The coupling device  100  includes a proximal portion  202  and a distal portion  204  that form a housing  106 . The proximal portion  202  and the distal portion  204  may be formed as an integral housing to provide a rigid coupling device  100 . In other embodiments, the proximal portion  202  and distal portions  204  are formed separately and interconnected to form the housing  106 . The proximal portion  202  and distal portion  204  are formed to permit relative rotation about one another. Housing  106  may be formed of a plastic, metal or any other material that can be properly sterilized for use in a surgical field. Any of the fabrication processes described above with respect to  FIG. 2  may be used in the fabrication of the housing  106  illustrated in the embodiment of  FIG. 5 . 
     In the exemplary illustration of  FIG. 5 , an engagement mechanism  112  (described with respect to  FIG. 2 ) is located within the distal portion  204  of lead channel  108  to permit gripping of a lead. This view also shows a gripping mechanism  214  designed to grip the connector pin  14 . Any gripping mechanism know in the art could be used to grip the pin  14 . The exemplary mechanism  214  is a hand actuated spring-clip  210  that employs the use of an actuating member  212  on the exterior surface of the proximal portion  202 . Functionally, the actuating member  212  is compressed to expand a gripping surface of the gripping mechanism  214  so as to position the pin  14  there-between or release the pin  14 . Conversely, releasing the compressing force exerted on the actuating member  212  causes the gripping surface to contract thereby engaging the pin  14 . 
     The coupling devices  100  of  FIGS. 2 and 5  optionally include a display  82  located on an outer surface of the device  100 . Displaying an indication of the sensed parameter either on the coupling device  100  or on the programmer  30  is beneficial to the implanting procedure. Real time display of the sensed parameters, as the lead  12  is navigated through the patient  10  will, for example, facilitate the optimization of the implant location within the target tissue. As previously described, any of the aforementioned parameters may be sensed. In one embodiment the sensed signal is displayed as a “raw” number; in other words, the plain sensed parameter is displayed without further action. In other embodiments, the sensed parameter is processed by microcomputer  162  to derive an indication that serves as a direct feedback to the implanting physician. 
     One example of a parameter that may be sensed and displayed, with or without, processing is impedance. The electrodes on lead  12  could be utilized to perform impedance measurements of the surrounding tissue or fluid as the lead  12  is progressively inserted into patient  10 . The typical impedance value of blood is usually about 600 ohms while body tissue will range from about 800 ohms to over 1400 ohms. The variation of the body tissue impedance will depend on the amount of fluid in the tissue. Tissue with a normal amount of fluid is generally about 1000 ohms. Accordingly as the lead  12  is navigated through the vein (blood) into the target tissue, the impedance value will increase from about 600 ohms to 1000 ohms. This abrupt change in impedance measurement serves as an indicator to the implanting physician that lead  12  is currently in contact with tissue. The raw impedance values may be displayed and the physician may correlate the measure value with the surrounding matter e.g., plain blood, tissue with minimal fluid. Alternatively, the impedance values may be processed according to various criteria within the microprocessor  162 , and an indication of the particular matter within which the lead  12  is in contact displayed. 
     Additionally, the aforementioned helical coil located on lead  12  is typically rotated to secure the lead tip in the tissue. One issue that may arise with rotation of the helical coil is over-rotation that may result in damage to the tissue. It may be noted that the impedance of tissue will vary depending on the amount of fluid in the tissue. Hence, aided with display  82  and impedance processing on microcomputer  162  on certain embodiments of coupling device  100 , impedance measurements may be performed to facilitate the determination of when the helical coil is sufficiently rotated. As the rotation of the helical coil is performed, fluid is squeezed out of the tissue and the impedance measurement consequentially increases serving as an indication that the lead tip is successfully lodged in the tissue such that further rotation is not necessary. Moreover, because over-rotation may cause tissue damage, further rotation of the helical coil will allow blood to re-enter the fixation site and consequentially the impedance value drops. The impedance measurements performed during the rotation are displayed in real-time as the rotation occurs. Changes in impedance measurements serve as an indicator of the amount of fluid displaced from the tissue and these measurements are indicative of the portion of the helical coil that is embedded into the tissue. Thus measuring the impedance value of the tissue as the helical coil is rotated facilitates the prevention of over-rotation of the lead and thus minimizes or reduces tissue damage. 
     Furthermore, the coupling device  100  may determine whether the implant location is optimal by sensing or receiving an indication of an unintended consequence. One example is phrenic nerve stimulation which may occur with a left ventricular (LV) lead since the LV lead is often implanted proximate this nerve. Either due to position or due to elevated levels for stimulation therapy, the phrenic nerve might be stimulated by the LV lead. Thus by delivering electrical energy stimulation concurrently during the implant procedure, the implanting physician may be able to identify an appropriate placement position based on the stimulation levels required for the intended therapy. 
     As mentioned the alternative embodiments of coupling device  100  illustrated in  FIGS. 2 and 5  can be fabricated from any suitable material, including plastic or metal that can be properly sterilized for use in a surgical field. Some examples of sterilizing techniques are the use of flash steam (thus the material would need to be able to withstand high temperature) or sterilizing chemicals such as Ethylene Oxide (hence the material would need to be compatible with the chemical) or nitrogen gas (similarly the material would need to be compatible with the gas). In yet other alternative embodiments, the coupling device  100  includes a polymer layer that is disposed over the housing for ease of cleaning and sterilization such as epoxy or polyester. 
       FIG. 6A  is a functional flowchart illustrating the over-all stand-alone operation of the coupling devices of  FIGS. 2 and 5  in conjunction with a lead. At  600 , the lead  12  is connected to the coupling device  100  by inserting the proximal end  13  of the lead  12  through the distal opening  107  of the coupling device  100  and advancing the lead  12  through the lead receiving channel  108  toward the proximal opening  105  of the coupling device  100 . The electrical connector assembly of the lead is aligned with the electrical contacts  122 ,  124  of the coupling device  100  so as to be in contact. 
     Next, the implanting physician makes a determination of whether it is desired to use the coupling device  100  to navigate  610  the lead  12 . If desired, the body of the lead  12  is securely coupled to the coupling device  100  using any implementations of the engagement mechanisms  112  described above. Additionally, in alternative implementations having a pin gripping mechanism  214 , the physician decides whether to use the coupling device  100  for rotation of the pin. If desired, the lead pin  14  may be securely coupled to the coupling device  100 . Further, the implanting physician determines whether to use a guiding tool  18  to navigate the lead  12  and selects the desired tool  18 . The tool  18  is inserted into the lumen  15  of the lead  12 . 
     At  610 , the implanting physician then proceeds to navigate the lead  12  through the patient  10  to the desired tissue location. Once the lead  12  is advanced into the general area where it is desired to affix the lead  12 , the physician positions  620  the distal end of the lead  12  against the tissue. The coupling device  100  is activated to provide electrical energy  630  to the tissue through the lead  12 . In alternate embodiments, providing electrical energy from the coupling device  100  is also performed during the process of navigation of the lead  12 . 
     Additionally, the physician may activate the coupling device  100  at  635  to sense one or more parameters described above through the lead  12 . In one embodiment, the sensed parameters are displayed  640  on the display  82  included on the coupling device  100 . The sensed parameters are used at  650  to derive an indication of whether the implant location is appropriate or to verify if capture has occurred. 
     If the displayed parameters do not indicate that a desired response is achieved, the lead functionality is evaluated  655 . In one embodiment, the evaluation  660  of lead functionality is performed through providing electrical energy to the lead  12  and determining if the energy is conducted to the distal end by observing tissue response. Alternatively, the coupling device  100  initiates sensing of various parameters via the lead  12 , and the sensed parameters received by the device are evaluated  660  to determine lead functionality. If it is determined that the functionality of the lead is inappropriate, the lead  12  is replaced at  665 . Otherwise, the physician re-positions the lead  12  at  620  and repeats the above steps until an appropriate response is achieved. Upon achieving a desirable response, the coupling device  100  is disconnected and the implant procedure is completed  670  by connecting the implantable medical device and closing the incision site. 
       FIG. 6B  is a functional flowchart illustrating an alternative over-all operation of the coupling devices  100  of  FIGS. 2 and 5  in conjunction with a lead  12  whereby the coupling devices  100  have wireless communication capability. In the alternate embodiment, the coupling device  100  is in communication with an external device  30 , such as a programmer. Thus the operation to provide electrical energy  630  is alternatively initiated from an external device  30  that is in communication with the coupling device  100 . Similarly, the operation to sense one or more parameters  635  is alternatively initiated from the external device  30 . It will be noted that the sensed parameters may alternatively, or additionally, be displayed at an external display  30  such as that available on the external device  30 . Thus at  645 , the sensed parameters may be transmitted to the external device  30  and subsequently displayed, if desired. 
     Although the present disclosure has been described according to specific embodiments, it is recognized that with the benefit of this disclosure, one of ordinary skill in the art may conceive variations of these embodiments that generally gain the benefits provided by a remote lead coupling device. The above described embodiments should therefore not be considered limiting in regard to the following claims.