Abstract:
The ICD/VAD defibrillator electromagnet is used with patients who possess either an ICD or a VAD. The electromagnet has a slim, low-profile design and an adhesive pad that allows for proper positioning to patient&#39;s chest, a decrease risk for pressure related wounds, and also permits the positioning of the patient in any of multiple planes while in surgery/X-ray without worry about displacement or shifting of the electromagnet. The electromagnet provides protection and safety for patients undergoing surgery involving electrocaurtery as well as, helping patients in X-ray/CT/MRI procedures that produce high magnetic fields that interfere with ICD/VAD proper function.

Description:
RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional Application Ser. No. 62/026,488 entitled “ICD/VAD Defibrillator Electromagnet” that was filed on Jul. 18, 2014 which is incorporated herein by this reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. External Medical Device 
         [0003]    The present invention relates to medically implanted devices (MID) such as Implanted Cardiovertor Defibrillators (ICDs) and/or Ventricular Assist Devices (VADs) and methods for protecting the MID from either Conductive or Radiated Electromagnetic Interference (EMI). More specifically, the present invention relates to the ability to place the ICD/VAD in a triggered or asynchronous mode. ICD/VADs now can have the arrhythmia detection suspended intermittently at a medical provider&#39;s discretion or in concert with external generator activation by a surgeon before, during, and after EMI producing activities are suspected to accrue. The present invention also relates to methods that protect the MID from electromagnetic interference (EMI) that may alter the performance of implanted cardiac devices and provides strategies to minimize negative effects on patient hemodynamic status. 
         [0004]    2. The Relevant Technology 
         [0005]    Patients with MIDs may be subjected to medical procedures in which EMI producing equipment (e.g., electrosurgery, cautery or RF ablation) is used. Some types of interference may not be filtered out by MID sensing and may be erroneously interpreted as a rapid heart rate. If persistent, this interference could cause the tachyarrhythmia detection criterion to be met and a tacharrhythmia therapy to be inappropriately delivered. Accordingly, there are instances when it is desirable to temporarily suspend the tachyarrhythmia detection capabilities of an MID. 
         [0006]    Most pacemakers and ICDs have built-in magnetic reed switches that are designed to switch “ON” or “OFF” the tachyarrhythmia detection circuitry in response to magnets. Some newer devices are equipped with alternative technologies like giant magnetosensitive resistors (GMRs), Hall-effect sensors, or telemetry coils that also respond to magnets. 
         [0007]    Clinical magnets, made of ferrous alloy, are known in the industry and come in various shapes (ring or doughnut, horseshoe, and rectangle or bar) and are design to overlay the ICD/VAD implantation site. Such clinical magnets are permanent magnets that cannot be turned off and on. By properly placing such clinical magnets proximate the MID, the operation of the MID can be temporarily suspended until the clinical magnet is removed from its proper placement. Unfortunately, such clinical magnets move inadvertently during medical procedures prematurely allowing the MID to operate and/or the clinical magnets can cause wounds to the patient by tight adherence or undesired pressure at the clinical magnet site. 
         [0008]    Several clinical magnets are known in the art. These clinical magnets require proper placement as per manufacturer (white papers) recommendations. Ring/doughnut magnets and bar magnets, the St. Jude Telemetry Wand magnet with a removable magnet, and the Medtronic Smart Magnet™ are known and have been used to turn off implantable cardioverter defibrillators. 
         [0009]    One type of clinical magnet is produced by Medtronic (Minneapolis, Minn., USA) and is known as the Smart Magnet™. The Medtronic Smart Magnet™ has a light indicator to guide appropriate placement and is a permanent magnet produced with an external, rigid injection-molded enclosure to withstand robust handling. Because the Smart Magnet™ is a permanent magnet, its magnetic field cannot be turned off and on or varied in strength. Rather, its magnetic field has a given strength and is always on. To remove its effect on an MID, it must be removed from positioning proximate the MID. Also, the Smart Magnet™ is sold without means provided to adhere it to a patient. Hence, external means of adherence such as adhesive, tape, or elastic wrap must be used to secure the magnet in the vicinity needed to properly suspend operation of the MID. Likewise, the external means of adherence such as adhesive, tape, or elastic wrap must be removed to allow the magnet to be removed from the vicinity of the MID to allow operation of the MID to recommence. If the Smart Magnet™ needs to be reintroduced during the medical procedure, it must be repositioned properly and re-adhered to make certain that it has the desired effect on the MID. When placed properly, the Smart Magnet™ results in the expected response from MIDs; however, the indicator illuminates only when used with Medtronic MIDs. 
         [0010]    Another type of clinical magnet is the St. Jude Telemetry Wand magnet which is also available for use with ICD/VADs. Again, the St. Jude Telemetry Wand magnet is a permanent magnet that cannot be turned off and on, although the magnet may be removed from the wand. 
         [0011]    The magnetic field effect of each of these clinical magnets is directly proportional to the strength of the magnet and inversely proportional to the distance of the magnet from the ICD/VAD. These available clinical magnets usually have a strength of &gt;90 Gauss. With each of these clinical magnets, temporary adhesion of the magnet to the skin is a challenge due to difficult patient positioning (lateral/prone), body size, or the length of procedure. 
         [0012]    It will also be appreciated that when using presently available clinical magnets, the current magnet systems are difficult to position correctly on a prone or lateral patient and on morbidly obese patients. The current magnets also increase the chance of pressure wounds (skin breakdown) due either to increased duration of procedure or external pressure forces from positioning devices. Consequently, patients frequently experience discomfort due to the improper positioning of the magnets or due to positioning failure and/or dislodging during a procedure. Patients also experience pressure wounds caused by the size and rigidity of the clinical magnets. 
         [0013]    It would be an advancement in the art for a magnet to alleviate such problems while providing dependable suspension of the MID&#39;s operation. 
       BRIEF SUMMARY OF THE INVENTION 
       [0014]    The present disclosure has been developed in response to the current clinical magnets available on the market, and in particular, in response to the problems of improper positioning of clinical magnets, movement of the clinical magnet on patients once positioned, draped, anesthetized, or placed in X ray/CT/MRI; as well as, the pressure wound potential from clinical magnets and external forces from positioning a patient prone/lateral or for prolonged surgical duration. These are needs in the clinical magnets that have not yet been fully resolved by magnets currently available in the marketplace. 
         [0015]    The exemplary electromagnet of the present disclosure is made to be placed directly over the patients&#39; ICD/VAD, enabling proper temporary adhesion of the electromagnet to the skin due to difficult patient positioning (lateral/prone), body size, or length of procedure and provides protection from use of either a conductive or radiated EMI source. The exemplary electromagnet comprises a thin wafer wrapped in conductive wire (such as copper or other conductive metallic wire). The thin wafer may have any of numerous shapes so long as it maintains a low profile when wound with the conductive wire. Additionally, the thin wafer may be made of any material that becomes electromagnetic when electrical current is introduced to the conductive wire. 
         [0016]    Positive and negative poles are established so that the wire carries an electrical current to produce the electromagnet. The electromagnet is disposed inside an insulated gel adhesive pad with an electrical cord attached to a controller which is attached to a suitable power source such as an external battery pack or an AC outlet. Of course, electromagnets of various strengths may have differing numbers of wrappings (or windings) around the thin wafer. Also, a standard electromagnet may have a predetermined number of wrappings of conductive wire about the thin wafer, and still have adjustable magnetic strength by adjusting the amount of electrical current sent through the wrappings of conductive wire. 
         [0017]    The controller may have an LED light indicator that lights when the electromagnet is activated. The power source may be any suitable power source such as, for example, the external battery pack mentioned, an AC power source and inverter, or an external electrocautery generator source (e.g., Bovie generator, APC/Erby Generator). 
         [0018]    If the external electrocautery generator is the source, a time relay resistor with a short delay (5-10 seconds, for example) may be provided so that the electromagnet is activated shortly before the electrocautery device and remains active until shortly after the electrocautery device is deactivated. This resistor, once activated by the external electrocautery generator, triggers the ICD/VAD, placing it in an asynchronous mode before the EMI source is activated and used, and maintains that asynchronous mode until after the EMI source is deactivated. Again, the controller may have an LED light indicator that illuminates when the electromagnet is active. This allows the external electrocautery generator to power the electromagnet and to serve as a grounding source as well. 
         [0019]    The defibrillator electromagnet structure of the exemplary embodiments of the present disclosure may have the same or similar ferrous alloy design, but has a substantially slimmer profile design, weight less, and has an adhesive pad to help with better positioning and adhesion of electromagnet compared to magnets currently on the market for use with MIDs. The ability to trigger the asynchronous mode through an external battery pack, external generator, or other power source allows for more effective management of patients hemodynamic status and allows the ICD/VAD to function at optimal settings to benefit the patient. 
         [0020]    The exemplary defibrillator electromagnets of the present disclosure are activating/deactivating non-invasive ICD/VAD electromagnets having a low profile and may be disposed in a non-conductive adhesive gel pad to aide with correct positioning over the ICD/VAD. The slim profile also decreases the risk of pressure wounds due to prone/lateral positioning or prolonged procedures. The exemplary electromagnets have the ability to suspend arrhythmia detection intermittently at an operator&#39;s (i.e., medical provider) discretion or in concert with external generator activation by an operator surgeon before, during, and after EMI producing activities, allowing the ICD/VAD to function at optimal settings. This ability to suspend arrhythmia detection intermittently is unlike It differs from currently available magnets that once positioned over the ICD/VAD, triggering the asynchronous mode, the ICD/VAD cannot react to an arrhythmia detection unless the currently available magnet (all are permanent magnets) is physically removed from patient&#39;s chest. 
         [0021]    These differences and other features of the present disclosure will become more fully apparent from the following description, or may be learned by the practice of the invention as set forth hereinafter. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0022]    In order that the manner in which the above-recited and other features and advantages are obtained by the exemplary embodiments of this disclosure will be readily understood, a more particular description of the exemplary embodiments briefly described above will be rendered by reference to specific exemplary embodiments which are illustrated in the appended drawings. Understanding that these drawings depict only typical exemplary embodiments and therefore are not to be considered limiting in scope, the exemplary embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
           [0023]      FIG. 1  is a side elevation view of a patient lying supine showing an exemplary embodiment of an electromagnetic system with an exemplary electromagnet pad in relation to an MID, wherein a controller and power components are shown schematically; 
           [0024]      FIG. 2  is a schematic view of an exemplary electromagnetic system showing the interior of an exemplary electromagnetic pad with a portion cut away to reveal the low-profile electromagnet and the cushioning gel; 
           [0025]      FIG. 3  is a side elevation view of a patient lying supine showing another exemplary electromagnetic system with an exemplary electromagnet pad in relation to an MID, wherein a controller and power components of an electrocautery system are shown schematically; 
           [0026]      FIG. 4  is a schematic view of an alternative, exemplary embodiment of the electromagnetic system showing the connection to an electrocautery system and the interior of an electromagnetic pad with a portion cut away to reveal an exemplary low-profile electromagnet; and 
           [0027]      FIG. 5  is a schematic view of another alternative, exemplary embodiment of an electromagnetic system showing an alternative connection to a controller and an electrocautery system while showing the interior of an exemplary electromagnetic pad with a portion cut away to reveal an exemplary low-profile electromagnet. 
       
    
    
     REFERENCE NUMBERS 
       [0028]      
         [0000]    
       
         
               
               
             
           
               
                   
               
             
             
               
                 ICD/VAD defibrillator 
                 electromagnet pad 12 
               
               
                 electromagnet system 10 
               
               
                 controller 14 
                 power source 16 
               
               
                 patient 18 
                 medically implanted device (MID) 20 
               
               
                 wire 22 
                 wire 24 
               
               
                 electromagnet 26 
                 thin wafer 28 
               
               
                 conductive wire 30 
                 obverse panel 32 
               
               
                 reverse panel 34 
                 gel 36 
               
               
                 LED light indicator 38 
                 ON/OFF switch 40 
               
               
                 external battery pack 42 
                 external electrocautery generator 44 
               
               
                 grounding pad 46 
                 foot pedal 48 
               
               
                 electrocautery wand or pen 50 
                 signal wire 52 
               
               
                 delay circuitry 53 
                 electrocautery devices 54 
               
               
                 OFF/ON button 55 
                 dial 58 
               
               
                   
               
             
          
         
       
     
       DETAILED DESCRIPTION OF THE INVENTION 
       [0029]    The exemplary embodiments of the present disclosure will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. It will be readily understood that the components of the exemplary embodiments, as generally described and illustrated in the figures herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the exemplary embodiments, as represented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of exemplary embodiments of the invention. 
         [0030]    The word “exemplary” is used exclusively herein to mean “serving as an example, instance, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments. While the various aspects of the embodiments are presented in drawings, the drawings are not necessarily drawn to scale unless specifically indicated. 
         [0031]    The ICD/VAD defibrillator electromagnet system  10  has been developed in response to the deficiencies of clinical magnets currently available on the market, and in particular, in response to the problems of improper positioning of clinical magnets, movement of the clinical magnet on a patient&#39;s chest once positioned, draped, anesthetized, or placed in X ray/CT/MRI; as well as, the pressure wound potential from large and heavy clinical magnets and external forces from positioning a patient prone/lateral or for prolonged surgical duration. 
         [0032]    The ICD/VAD defibrillator electromagnet system  10 , as shown in  FIG. 1 , comprises an electromagnet pad  12 , a controller  14  and a power source  16 . As depicted, the electromagnet pad  12  is positioned on the skin surface of the chest of a patient  18  directly above a subsurface implanted MID  20 , such as an ICD or a VAD. The electromagnet pad  12  is connected to the controller  14  via wire  22 , and the controller  14  is connected to the power source  16  via wire  24 . Wires  22 ,  24  carry electrical current from the power source  16 , through the controller  14 , to the electromagnet pad  12 . 
         [0033]    As indicated above, it is important that the exemplary electromagnet pad  12  is positioned and adhered to the chest of the patient  18  directly above the MID  20  in a manner designated by the manufacturer of the MID  20 . The exemplary electromagnet (see  FIG. 2 ) within the electromagnet pad  12  is made to be placed directly over a patient&#39;s ICD/VAD. The electromagnet pad  12  has an adhesive backing (not shown) that enables proper, temporary adhesion of the electromagnet to the skin despite difficult patient positioning (lateral/prone), body size, or length of procedure and provides protection from use of either a conductive or radiated EMI source. Such adhered positioning assures that the electromagnet within the electromagnet pad  12  can suspend arrhythmia detection of the MID  20  intermittently. 
         [0034]    Turning now to  FIG. 2 , the exemplary electromagnet  26  comprises a thin wafer  28  (comprised of iron or a ferrous alloy or any other suitable metal that will become magnetic) that is wrapped in conductive wire  30  (such as copper or other conductive metallic wire) windings. Positive and negative poles are established so that conductive wire  30  carries an electrical current to activate the electromagnet  26 . The number of times that the conductive wire  30  is wrapped (wound) around the thin wafer  28  will determine the strength of the electromagnet  26  for a given electrical current. As a result, electromagnets  26  may be made having various different strengths to match with the requirements for various MIDs  20 . Of course, an adjustable electromagnet  26  may have a predetermined number of wrappings of the conductive wire  30  (as a standard) and the strength of the electromagnet  26  may be adjustable by adjusting the electrical current applied to the conductive wire  30 . For purposes of this disclosure, the number of wrappings of the conductive wire  30  depicted in  FIGS. 2 ,  4 , and  5  have been limited so not to obscure the underlying thin wafer  28 . Therefore, the wrappings depicted should not be construed to designate the number of wrappings that are required for the embodiments to operate as intended. 
         [0035]    The electromagnet  26  is disposed inside the electromagnetic pad  12  which comprises an obverse panel  32  and reverse panel  34  that presents the electromagnet  26  in a low-profile configuration to significantly reduce the likelihood of pressure wounds and the dislodging of the electromagnet  26  from its intended position. 
         [0036]    In an exemplary embodiment, the reverse panel  34  has an adhesive backing (not shown) to secure temporarily the electromagnetic pad  12  to the patient  18 . Either or both of the obverse panel  32  and reverse panel  34  may have a non-conductive gel  36  within the panel  32 ,  34  to insulate the patient  18  from electrical shock while not affecting the magnetic field created by the electromagnet  26 . 
         [0037]    As shown in  FIG. 2 , the controller  14  may have an LED light indicator  38  that lights when the electromagnet  26  is activated. In some embodiments, the controller  14  may also have an ON/OFF feature such as an ON/OFF switch  40  that the medical provider may operate to turn the electromagnet  26  on or off at discretion. The controller  14 , in some embodiments, may operate additional devices other than the electromagnet  26 , as will be described below. It should be understood that a skilled artisan will know how to configure the circuitry within the controller  14  to turn the electromagnet  26  on and off, illuminate the LED light indicator  38  or other indicators (such as other lights or audible alerts), and operate other devices such as, for example, an electrocautery pen or wand. 
         [0038]    The power source  16  depicted in  FIG. 1  may be any suitable power source  16  such as, for example, an external battery pack  42  ( FIG. 2 ), an AC power source and inverter (not shown, but contemplated), or an external electrocautery generator source (see  FIGS. 3-5 ). As the strength of an electromagnet  26 , having a given number of windings of the conductive wire  30 , can be increased or decreased by increasing or decreasing the power to the electromagnet  26 , it is contemplated that the power source  16  may have the capability to supply power adjustability to adjust the strength of the electromagnet  16  in some embodiments where the ability to adjust the strength of the electromagnet  26  would be advantageous. 
         [0039]    When the electromagnet  26  is active, thereby creating a magnetic field, it causes the suspension of arrhythmia detection by the MID  20  so that the presence of EMI will not be misinterpreted as an arrhythmia event. The medical provider can turn the power to the electromagnet  26  off and on in any of a number of ways that are described herein so that the operation of the MID  20  is suspended during the likely presence of EMI. 
         [0040]      FIGS. 3-5  illustrate two alternative, exemplary embodiments of the ICDS/VAD defibrillator electromagnet system  10 . In  FIGS. 3 and 4 , the ICDS/VAD defibrillator electromagnet system  10  comprises an electromagnet pad  12 , a controller  14  and a power source  16 . As depicted, the electromagnet pad  12  is positioned on the skin surface of the chest of a patient  18  directly above a subsurface implanted MID  20 , such as an ICD or a VAD. It should be understood that the electromagnet pad  12  is described as working to suspend the operation of MIDs such as ICDs and VADs, but the electromagnet pad  12  could be used to activate/deactivate any implanted or subcutaneous device that responds to the presence of a magnetic field by initiating/suspending operation until the magnetic field is removed. The electromagnet pad  12  is connected to the controller  14  via wire  22 , and the controller  14  is connected to the power source  16  via wire  24 . Wires  22 ,  24  carry electrical current from the power source  16 , through the controller  14 , to the electromagnet pad  12 . 
         [0041]    Again, it is important that the electromagnet pad  12  is positioned and adhered to the chest of the patient  18  directly above the MID  20  in a manner designated by the manufacturer of the MID  20 . The electromagnet  26  within the electromagnet pad  12  is made to be placed directly over a patient&#39;s ICD/VAD. The electromagnet pad  12  has an adhesive backing (not shown) that enables proper, temporary adhesion of the electromagnet  26  proximate to the skin despite difficult patient positioning (lateral/prone), body size, or length of procedure and provides protection from use of either a conductive or radiated EMI source. Such positioning assures that the electromagnet  26  within the electromagnet pad  12  can suspend arrhythmia detection of the MID  20  intermittently. 
         [0042]    As described above, the exemplary electromagnet  26  comprises a thin wafer  28  that is wrapped in conductive wire  30 . The thin wafer  28  may have any suitable shape such as disc, a ring or doughnut, a horseshoe, a rectangle or bar, or any other suitable shape that may deliver the desired magnetic field. Positive and negative poles are established so that conductive wire  30  carries an electrical current to activate the electromagnet  26 . The electromagnet  26  is disposed inside the electromagnetic pad  12  which comprises an obverse panel  32  and reverse panel  34  that presents the electromagnet  26  in a low-profile configuration to significantly reduce the likelihood of pressure wounds and the dislodging of the electromagnet  26  from its intended position. In an exemplary embodiment, the reverse panel  34  has an adhesive backing (not shown) to secure temporarily the electromagnetic pad  12  to the patient  18 . Either or both of the obverse panel  32  and reverse panel  34  may have a non-conductive gel  36  (not shown in  FIG. 4  or  5 ) within the panel  32 ,  34  to insulate the patient  18  from electrical shock while not affecting the magnetic field created by the electromagnet  26 . 
         [0043]    The controller  14  may have LED light indicators  38  that light when the electromagnet  26  is activated and/or to signal various conditions existing in the system. Additional LED light indicators  38  also may be used to serve as visual alerts of the existence of various conditions such as an intensity threshold, the operation of an additional device, or any other desired alert. In the exemplary embodiments shown in  FIGS. 3 and 4 , the controller  14  may not have an ON/OFF switch  40  that the medical provider operates to turn the electromagnet  26  on or off at discretion. Rather, the operation of the electromagnet  26  is coincident with the power being provided by an external electrocautery generator  44  (e.g., a Bovie generator or an APC/Erby generator). The power source  16  may be any suitable power source  16  such as, for example, an external battery pack  42  ( FIG. 2 ), an AC power source and inverter (not shown, but contemplated), or an external electrocautery generator  44  (see  FIGS. 3-5 ). 
         [0044]      FIGS. 3 and 4  show exemplary embodiments where the external electrocautery generator  44  controls the delivery of electrical current to the electromagnet  26  and determines when arrhythmia detection of the MID  20  is suspended. Controller  14  is connected to the external electrocautery generator  44  via wire  24 . Of course, wire  24  may have an adaptor (not shown) that plugs into the external electrocautery generator  44  in a similar fashion as do other attachments. Those skilled in the art will understand what types of adaptors will serve to provide power from the external electrocautery generator  44  to the controller  14  for delivery to the electromagnet  26 . 
         [0045]    As shown, the external electrocautery generator  44  serves as the power source  16  and may control and/or provide power to several attachments. One attachment may be a grounding pad  46  that is secured to the patient  18  to provide an electrical ground for the system. Another attachment, for example, may be a foot pedal  48  that signals the power source  16  to supply power to an electrocautery wand or pen  50  which is another attachment. When the foot pedal  48  is depressed by the medical provider, a signal is sent through signal wire  52  to the power source  16 . The power source  16  understands such signal as an instruction to provide power to the electrocautery wand or pen  50 . In some embodiments, the power source  16  also understands such signal as an instruction to provide power to the controller  14  and the electromagnet  26 . Hence, power is provided simultaneously to the electrocautery wand or pen  50 , the controller  14 , and the electromagnet  26 . In this manner, the medical provider can turn the electromagnet  26  on and off at discretion by depressing and releasing the foot pedal  48 . 
         [0046]    In other exemplary embodiments, delay circuitry  53  is provided that delays the supply of power to the electrocautery wand or pen  50  until a short while after power is supplied to the electromagnet  26  so that arrhythmia detection of the MID  20  is suspended shortly before the electrocautery wand or pen  50  becomes active. The delay may be only a few seconds (for example, 5-10 seconds) or may be longer or shorter as desired. In fact, the delay may be adjustable within a range by moving a dial (see  FIGS. 4 and 5  for example) supplied for that purpose. Additionally, the delay circuitry  53  may also cause a reverse delay that turns off the electrocautery wand or pen  50  shortly before the electromagnet  26  is turned off. As shown in  FIGS. 3 and 4 , the delay circuitry  53  (shown in schematic phantom lines) is internal to the external electrocautery generator  44 . 
         [0047]    The delay circuitry  53  may comprise a time relay resistor with a short delay (5-10 seconds, for example) that is provided so that the electromagnet  26  is activated shortly before the electrocautery device  54  and remains active until shortly after the electrocautery device  50  is deactivated. This resistor, once activated by external electrocautery generator  44 , triggers the MID (ICD/VAD)  20 , placing it in an asynchronous mode before the EMI source is activated and used, and maintains that asynchronous mode until after the EMI source is deactivated. 
         [0048]    Some electrocautery devices  54  (such as the electrocautery pens  50  shown in  FIGS. 4 and 5 ) have an OFF/ON button (or switch)  55  that turns the electrocautery device  54  off and on. Similar to the use of the foot pedal  48 , when the OFF/ON button  55  is depressed or switch  55  is moved by the medical provider, a signal is sent through signal wire  52  to the external electrocautery generator  44 . The external electrocautery generator  44  understands such signal as an instruction to provide power to the electrocautery wand or pen  50 . In some embodiments, the external electrocautery generator  44  also understands such signal as an instruction to provide power to the controller  14  and the electromagnet  26 . Hence, power is provided simultaneously to the electrocautery wand or pen  50 , the controller  14 , and the electromagnet  26 . In this manner, the medical provider can turn the electromagnet  26  on and off at discretion by depressing and releasing the OFF/ON button  55  or by moving the switch  55 . 
         [0049]    Similarly, in some exemplary embodiments, delay circuitry  53  is provided that delays the supply of power to the electrocautery wand or pen  50  until a short while after power is supplied to the electromagnet  26  so that arrhythmia detection of the MID  20  is suspended shortly before the electrocautery wand or pen  50  becomes active. The delay may be only a few seconds (for example, 5-10 seconds) or may be longer or shorter as desired. In fact, the delay may be adjustable within a range by moving a dial  58  supplied for that purpose. Additionally, the delay circuitry may also cause a reverse delay that turns off the electrocautery wand or pen  50  shortly before the electromagnet  26  is turned off. As shown in  FIG. 4 , the delay circuitry  53  is internal to the external electrocautery generator  44 . In this case, the dial  58  may be located on the controller  14 . In other embodiments, the delay circuitry  53  may be located in the external electrocautery generator  44  and the dial  58  may be on the external electrocautery generator  44  (not shown) or on a separate box (not shown) that could be located for easy access by the operator. 
         [0050]    Turning now to  FIG. 5 , the exemplary embodiment of the ICD/VAD defibrillator electromagnet system  10  shown utilizes controller  14  to cause the delay described above. Instead of having the delay circuitry  53  in the external electrocautery generator  44 , such delay circuitry  53  is provided in the controller  14 . In this manner, the external electrocautery generator  44  need not be modified to have such circuitry. Rather, the controller  14  with delay circuitry  53  may be connected to the external electrocautery generator  44  to retrofit the delay capability to the system without affecting the operation of the external electrocautery generator  44 . 
         [0051]      FIG. 5  shows an exemplary embodiment of the ICD/VAD defibrillator electromagnet system  10  where the controller  14  controls the delivery of electrical current to the electromagnet  26  and determines when arrhythmia detection of the MID  20  is suspended. Controller  14  is connected to the external electrocautery generator  44  via wire  24 . Of course, wire  24  may have an adaptor (not shown, but known to those skilled in the art) that plugs into the external electrocautery generator  44  in a similar fashion as do other attachments. Such adaptors may have one or more male prongs that engage corresponding female receptacles to provide a coupling required for the operation of the system as desired. The controller  14  may also have a receptacle (not shown) similar to what is provided on the external electrocautery generator  44  for receiving an adaptor (such as a male jack) on signal wire  52  connected to the electrocautery wand or pen  50 . Those skilled in the art will understand what types of adaptors will serve to provide power from the external electrocautery generator  44  to the controller  14  for delivery to the electromagnet  26  and to the electrocautery wand or pen  50 . 
         [0052]    As shown, the external electrocautery generator  44  may have a grounding pad  46  attachment that is to be secured to the patient  18  to provide an electrical ground for the system, and optionally a foot pedal  48  that signals the power source  16  to supply power to the controller  14  which in turn supplies power to the electromagnet  26  and the electrocautery wand or pen  50 . When the foot pedal  48  is depressed by the medical provider, a signal is sent through signal wire  52  to the external electrocautery generator  44 . The external electrocautery generator  44  understands such signal as an instruction to provide power to the electrocautery wand or pen  50  via the controller  14 . Hence, power is provided to the controller  14  which activates the electromagnet  26 . In this manner, the medical provider can turn the electromagnet  26  on and off at discretion by depressing and releasing the foot pedal  48 . 
         [0053]    In the exemplary embodiment shown, delay circuitry  53  is provided in the controller that delays the supply of power to the electrocautery wand or pen  50  until a short while after power is supplied to the electromagnet  26  so that arrhythmia detection of the MID  20  is suspended shortly before the electrocautery wand or pen  50  becomes active. The delay may be only a few seconds (for example, 5-10 seconds) or may be longer or shorter as desired. In fact, the delay may be adjustable within a range by moving a dial  58  supplied for that purpose. The dial  58  may be located on the controller  14  or on a separate box (not shown) that could be located for easy access by the operator. 
         [0054]    Additionally, the delay circuitry  53  may also cause a reverse delay that turns off the electrocautery wand or pen  50  shortly before the electromagnet  26  is turned off. As shown in  FIG. 5 , the delay circuitry  53  is internal to the controller  14  and provides a retrofit delay capability to the overall system. 
         [0055]    The delay circuitry  53  may comprise a time relay resistor with a short delay (5-10 seconds, for example) that is provided so that the electromagnet  26  is activated shortly before the electrocautery device  54  and remains active until shortly after the electrocautery device  54  is deactivated. This resistor, once activated by controller  14 , triggers the ICD/VAD, placing it in an asynchronous mode before the EMI source is activated and used, and maintains that asynchronous mode until after the EMI source is deactivated. 
         [0056]    Again, the controller may have an LED light indicator  38  that illuminates when the electromagnet  26  is active. This embodiment also allows the external electrocautery generator  44  to power the electromagnet  26  through the controller  14  and to serve as a grounding source as well. 
         [0057]    The defibrillator electromagnet structure of the exemplary embodiments of the present invention may have the same or similar ferrous alloy design, but has a substantially slimmer profile design, less weight and has an adhesive pad to help with better positioning and adhesion of electromagnet compared to current market magnets. The ability to trigger the asynchronous mode through an external battery pack, external generator, or other power source allows for more effective management of patient&#39;s hemodynamic status and allows the ICD/VAD to function at optimal settings to benefit the patient. 
         [0058]    The defibrillator electromagnet is a non-invasive ICD/VAD electromagnet that has a low profile and is disposed in a non-conductive adhesive gel pad to aide with correct positing over the ICD/VAD. Its slim profile also decreases the risk of pressure wounds due to prone/supine/lateral positioning or prolonged procedures. The electromagnet&#39;s ability to have arrhythmia detection suspended intermittently at medical provider discretion or in concert with an external generator activation by the medical provider before, during, and after EMI producing activities, allows the ICD/VAD to function at optimal settings. It differs from current magnets available that once positioned over the ICD/VAD, triggering the asynchronous mode, the ICD/VAD cannot react to an arrhythmia detection unless the permanent magnet is removed from patient&#39;s chest. 
         [0059]    The present invention may be embodied in other specific forms without departing from its structures, methods, or other essential characteristics as broadly described herein and claimed hereinafter. The described embodiments are to be considered in all respects only as illustrative, and not restrictive. The scope of the invention is, therefore, indicated by the appended claims, rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.