Abstract:
A telemetry wake-up circuit is electrically disposed between a telemetry transceiver associated with an AIMD, and an RF tag. The RF tag may be remotely interrogated to generate a signal to which the telemetry wake-up circuit is responsive to switch the telemetry transceiver from a sleep mode to an active telemetry mode. In the sleep mode, the telemetry transceiver draws less than 25,000 nanoamperes from the AIMD, and preferably less than 500 nanoamperes.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This a application in a continuation-in-part of application Ser. No. 12/566,223, filed on Sep. 24, 2009, now U.S. Pat. No. 8,253,555, which is a continuation-in-part of application Ser. No. 12/407,402, filed on Mar. 19, 2009, now U.S. Pat. No. 8,195,295. This application also claims priority from provisional application Ser. No. 61/150,061, filed on Feb. 5, 2009, provisional application Ser. No. 61/144,102, filed on Jan. 12, 2009, provisional application Ser. No. 61/116,094, filed on Nov. 19, 2009, and provisional application Ser. No. 61/038,382, filed on Mar. 20, 2008. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates generally to telemetry transceivers associated with active implantable medical devices (AIMDs) and related components. More particularly, the present invention relates to AIMD RF telemetry circuits having radio frequency identification (RFID) controllable wake-up features. 
       FIGS. 1 and 2  provide a background for better understanding of the present invention. FIG. I is a wire formed diagram of a generic human body showing a number of implanted medical devices.  100 A represents a family of hearing devices which can include the group of cochlear implants, piezoelectric sound bridge transducers and the like.  100 B represents a variety of neurostimulators and brain stimulators. Neurostimulators are used to stimulate the Vagus nerve, for example, to treat epilepsy, obesity and depression. Brain stimulators are pacemaker-like devices and include electrodes implanted deep into the brain for sensing the onset of the seizure and also providing electrical stimulation to brain tissue to prevent the seizure from actually occurring. The lead wires associated with a deep brain stimulator are often placed using real time MRI imaging.  100 C shows a cardiac pacemaker which is well-known in the art.  100 D includes the family of left ventricular assist devices (LVAD&#39;s) and artificial hearts.  100 E includes an entire family of drug pumps which can be used for dispensing of insulin, chemotherapy drugs, pain medications and the like. Insulin pumps are evolving from passive devices to ones that have sensors and closed loop systems. That is, real time monitoring of blood sugar levels will occur. These devices tend to be more sensitive to EMI than passive pumps that have no sense circuitry or externally implanted lead wires.  100 F includes a variety of bone growth stimulators for rapid healing of fractures.  100 G includes urinary incontinence devices.  100 H includes the family of pain relief spinal cord stimulators and anti-tremor stimulators.  100 H also includes an entire family of other types of neurostimulators used to block pain.  100 I includes a family of implantable cardioverter defibrillators (ICD) devices and also includes the family of congestive heart failure devices (CHF). This is also known in the art as cardio resynchronization therapy devices, otherwise known as CRT devices.  100 J illustrates an externally worn pack. This pack could be an external insulin pump, an external drug pump, an external neurostimulator or even a ventricular assist device. 
       FIG. 2  is a prior art cardiac pacemaker  100 C. A cardiac pacemaker typically has an electromagnetically shielded and hermetically sealed housing  102  which is generally constructed from titanium, stainless steel or the like. It also has a plastic or Techothane header block  104  which houses ISO standard IS-1 type connectors  106 ,  108 . In the past, AIMDs, in particular pacemakers, ICDs and neurostimulators, embodied close-coupled telemetry circuits. The purpose of telemetry is so that the AIMD could be interrogated or even reprogrammed after implantation. For example, it is common to monitor battery status, patient biologic conditions and the like, through telemetry. In addition, an external telemetry programmer can be used to re-program the AIMD, for example, and put it into different modes of operation. In the past, for pacemakers and ICDs the telemetry was inductive (low frequency magnetic) and close coupled. In this older art it was typical that the AIMD would have a multiple turn wire antenna within its titanium housing. There were even AIMDs that used an external loop antenna of this type. To interrogate or re-program the AIMD, the physician or other medical practitioners would bring a wand, with a similar antenna embedded in it, very close to the AIMD. For example, for a typical pacemaker application the telemetry wand would be placed directly over the implant. The wand is/was connected with wiring to the external programmer. The medical practitioner would move the wand around until the “sweet-spot” was located. Once the wand is located in the “sweet-spot,” a communication link is established between the multiple turn wire antenna implanted in the AIMD and a similar multiple turn wire antenna located inside the telemetry wand. The external programmer would then become active and electrograms and other important information would be displayed. Typically the telemetry wand would be placed either against or very close to the patient&#39;s skin surface or at most a few centimeters away. 
     In the last few years, distance RF telemetry has become increasingly common. For distance telemetry, for example for a cardiac pacemaker  100 C, there would be a high frequency antenna that would be located outside of the AIMD shielded titanium housing  102 . This could, for example, be placed in or adjacent to the AIMD plastic header block  104 . The external antenna would communicate with an external programmer that would have its own RF transceiver. A typical band for such communication is in the 402 to 405 MHz frequency range (known as the MICS band). There are other bands that may be used for RF telemetry including gigahertz frequencies. A problem with such prior art RF distance telemetry circuits is that energy consumption is high because the receiver circuitry must be on all the time. 
     The Zarlink chip has provided one solution to this problem. The Zarlink chip uses higher frequencies (in the gigahertz range) to wake-up the lower frequency RF telemetry circuit which is generally in the MICS band. The higher frequency GHz receiver of the Zarlink chip is very energy efficient, however the device or chip still consumes an amount of idling energy from the AIMD battery to always be alert for its wake-up call. In general, this current draw link is in the order of 250 picoamperes (250,000 nanoamperes). This is still a significant amount of idling current over the life of the pacemaker and generally shortens the pacemaker life by at least one month. 
     Accordingly, there is a need for an RF activated AIMD telemetry transceiver that includes means responsive to a signal from an RF transmitter to place an AIMD telemetry transceiver into its active telemetry mode. During a sleep mode for the AIMD telemetry transceiver, the system should draw a minimal amount of power from the AIMD, on the order of 25,000 nanoamperes or less, and preferably 500 nanoamperes or less. A circuit connection is provided which would be responsive to a signal from the RF tag to place the telemetry transceiver into its active telemetry mode. Preferably, the entire wake-up feature would be externally powered by, for example, the energy coupled from an external/remote RF reader. Once the AIMD telemetry transceiver is placed into its active mode, a feature is needed wherein the AIMD telemetry circuit can go back into its quiescent sleep mode. Accordingly, there is need for circuits and/or programmer commands to place the AIMD telemetry receiver back into a sleep mode after a set amount of time or after a receipt of a signal from the external programmer. The present invention fulfills these needs and provides other related advantages. 
     SUMMARY OF THE INVENTION 
     The present invention relates to an RF (radio frequency) activated AIMD (active implantable medical device) telemetry transceiver, generally comprising: (1) a telemetry transceiver associated with the AIMD, (2) a passive RF tag associated with the telemetry transceiver, and (3) a telemetry wake-up circuit electrically disposed between the telemetry transceiver and the RF tag. The telemetry transceiver has an active telemetry mode wherein the telemetry transceiver is powered by the AIMD, and a sleep mode. The telemetry wake-up circuit is responsive to a signal from the RF tag to place the telemetry transceiver into the active telemetry mode. 
     In a preferred embodiment, the RF tag comprises a passive RF or RFID chip and an antenna. The RF chip typically includes at least four terminals, and the antenna preferably comprises a biocompatible antenna. As shown, the RF chip is disposed within a hermetic package to prevent contact between the RF chip and body tissue or body fluids. The RF chip may be disposed within a housing for the AIMD which, thus, serves as the hermetic package. Alternatively, the RF tag may be disposed within its own hermetic package and disposed within the header block for the AIMD. The RF chip is activated by a remote source, such as an RF transmitter such as an RFID reader/interrogator, which may be a wireless unit, or integrated into or tethered to an AIMD programmer. The signal from the RF tag to place the telemetry transceiver into the active telemetry mode is generated in response to activation of the RF chip. 
     The telemetry wake-up circuit typically comprises a microelectronic switch. The microelectronic switch may comprise a bipolar junction transistor (BJT) switch, a field effect transistor (FET) switch, a MOSFET switch, a MEMS switch, a unijunction transistor switch, a silicon-controlled rectifier (SCR) switch, a PIN diode switch, a P-N junction transistor switch, a P-N-P transistor switch, or an N-P-N junction switch. 
     In its sleep mode, the telemetry transceiver draws less than 25,000 nanoamperes from the AIMD, and preferably less than 500 nanoamperes. In one embodiment, a timing circuit is provided for switching the telemetry transceiver from the active telemetry mode to the sleep mode. The timing circuit is re-set responsive to the signal from the RF tag to place the telemetry transceiver into the active telemetry mode. In another embodiment, the telemetry transceiver includes a sleep mode circuit responsive to a signal from the RF tag or a remote RF or inductive low frequency magnetic coupling source, for switching the telemetry transceiver from the active telemetry mode to the sleep mode. 
     In the active telemetry mode, the telemetry transceiver communicates with the remote RF or inductive low frequency magnetic coupling source. This remote source may comprise an AIMD programmer. 
     Other features and advantages of the present invention will become apparent from the following more detailed description, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings illustrate the invention. In such drawings: 
         FIG. 1  is a wire formed diagram of a generic human body showing a number of implanted medical devices. 
         FIG. 2  is a prior art cardiac pacemaker. 
         FIG. 3  is an enlarged cross-sectional view of the cardiac pacemaker taken generally along the line  3 - 3  from  FIG. 2 . 
         FIG. 4  is a perspective view of a typical cardiac pacemaker embodying the present invention, wherein the RF tag is disposed within the header block. 
         FIG. 5  is an enlarged perspective view of the RF tag taken generally about the line  5 - 5  from  FIG. 4 . 
         FIG. 6  is a diagrammatic view illustrating the component parts of the RF activated AIMD telemetry transceiver of the present invention. 
         FIG. 7  is an electrical schematic of the circuitry illustrated in  FIG. 6 . 
         FIG. 8  is a system diagram illustrating operation of the present invention. 
         FIG. 9  is a system illustration similar to  FIG. 8 , except that an older style of external program is shown including a wand which is placed over the patient&#39;s AIMD. 
         FIGS. 10 and 11  are similar to  FIGS. 8 and 9 , illustrating that the RFID reader/interrogator can be incorporated either within or connected to the AIMD external programmer. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention, in a broad sense, relates to an RF activated AIMD telemetry transceiver which includes (1) a telemetry transceiver associated with an AIMD, having an active telemetry mode wherein the telemetry transceiver is powered by the AIMD, and a sleep mode; (2) a passive RF tag associated with the telemetry transceiver; and (3) a telemetry wake-up circuit electrically disposed between the telemetry transceiver and the passive RF tag. The telemetry wake-up circuit is responsive to a signal from the RF tag to place the telemetry transceiver in the active telemetry mode. In a preferred embodiment, the AIMD transceiver has a timer wherein it returns to its sleep mode after a predetermined amount of time. As an alternative, a remote AIMD programmer may send a signal to the AIMD telemetry antenna and associated transceiver telling it to turn off and return to its sleep mode. 
     In a preferred embodiment, the remote AIMD programmer can incorporate a low frequency (LF) RF transmitter or RFID reader/interrogator operating in the 50 to 135 KHz frequency range which would transmit a signal sufficient to penetrate right through the titanium housing of an AIMD and activate an embedded passive RF chip. The circuitry of the RF chip would be connected to telemetry circuits contained within the AIMD. For example, in the case of a pacemaker, the remote pacemaker programmer would send the RF signal as a wake-up call to turn on the AIMD telemetry receiving circuits so that the pacemaker could communicate with the remote AIMD programmer. 
     In a preferred embodiment, the RF chip is a four terminal RFID chip. RFID is widely used for inventory and article tracking. RFID operational protocols and frequencies have evolved worldwide. There are EPC and ISO standards, and also ANSI standards that cover the frequency band, forms of modulation, etc. In particular, the ISO 18,000 standards are particularly applicable to the present invention. For example, low frequency RFID systems operating below 135 kHz are governed by ISO 18,000-2. There are also standards governed by the standard body known as EPC Global which defines various UHF and HF RFID protocols. For example, EPC HF Class 1 covers 13.56 MHz. 13.56 MHz is also known as the RFID HF band and is covered by ISO 18,000-3. The use of a passive four terminal RFID tag for the present invention is preferred because the frequency allocations and other protocols have been worked out over the last couple of decades and have resolved themselves into these international standards. 
     The passive RFID tag draws no current at all from the AIMD battery. A passive RFID tag is entirely powered from the external reader/interrogator. This is what makes it possible to achieve such very low levels of current drop when the telemetry circuit is in its sleep mode. The only part of the AIMD transceiver or receiver that would be active at all is the electronic switch that is coupled to the RFID chip. In the case where this is a field effect transistor (FET) switch, the current draw would be exceedingly low. It is only when the RFID tag itself receives energy from an external source such as an RFID reader/interrogator, that it sends a pulse to activate the transceiver electronic switch, thereby waking up the entire AIMD telemetry transceiver circuitry. 
     The prior art Zarlink chip shortens a pacemaker battery life by over one month. The present invention would, in contrast, shorten a pacemaker battery life by only a portion of a single day. 
     There is another significant advantage to using a passive RFID tag to wake up the AIMD telemetry circuit. The RFID tag can be multifunctional. That is, when it receives a wake-up encoded pulse from an external reader/interrogator, it can act as the described telemetry wake-up trigger. However, by sending it an interrogation pulse, it can also be used to identify the make, model number, and/or identify MRI compatible features of the AIMD. 
       FIG. 3  is a cross-sectional view taken generally along section  3 - 3  from  FIG. 2 . Shown is a circuit board or substrate  110  which contains many electronic components and microelectronic chips which enable the AIMD  100 C to function. Also shown is an RF or RFID tag  112  which includes an antenna  114  and a four terminal RF or RFID chip  116 . Two of the leadwires that are routed to the RFID chip  116  are connected to the antenna  114 . There are also leadwires  118 ,  120  that are connected from the RFID chip  116  to AIMD telemetry transceiver circuitry  122  as shown. In a typical application, energy is received from a remote RFID reader/interrogator  124  ( FIG. 6 ) and coupled to the RFID tag  112  antenna  114 . A resonant circuit is formed between this antenna  114  and the RFID chip  116 . Normally, a capacitor  126  ( FIG. 7 ) would be placed in parallel with the antenna  114  to store energy. Once the RFID chip  116  receives the proper encoded signal from the reader/interrogator  124  ( FIG. 7 ), it is activated and transmits a wake-up signal via leadwires  118 ,  120  to the AIMD telemetry transceiver  122 . This wake-up pulse puts the telemetry transceiver  122  into its active mode so that it may communicate with its external/remote programmer  128  ( FIG. 6 ). The remote programmer  128  may be the older style close-wanded telemetry low frequency magnetic coupling-type ( FIG. 9 ) or it may be the newer RF distance telemetry-type ( FIG. 8 ). 
     Referring once again to  FIG. 3 , the RFID tag  112  and its associated component antenna  114  and RFID chip  116  need not be biocompatible or hermetic. This is because they are disposed inside the overall electromagnetically shielded and hermetically sealed housing  102  of the AIMD  100 C. There are advantages and disadvantages to this placement. The obvious advantage is the RFID tag  112  and all its associated components are in an environmentally inert environment and are never exposed to body tissue or body fluids. A disadvantage is the fact that the antenna  114  is disposed inside of the electromagnetically shielded housing  102  of the AIMD. This means, the antenna  114  can only effectively pick up low frequency RFID signals. These signals would typically be in the 50 to 135 kHz frequency range. The antenna  114  would be completely ineffective in picking up signals from an external RFID reader/interrogator  124  at HF (13.56 MHz) or higher frequencies. This is because the housing  102  of the AIMD would effectively shield such signals. 
       FIG. 4  illustrates a cardiac pacemaker  100 C having an RFID tag  112  which is mounted in the AIMD plastic header block  104 . In this application, the RFID antenna  114  would be more efficient because it is outside of the generally electromagnetically shielded housing  102  of the AIMD. Since the antenna  114  that is associated with the RFID tag  112  is now displaced within the plastic header block  104 , it can more effectively pick up signals from the RFID reader/interrogator  124 . In this case, the RFID frequency could still be in the low frequency range (LF) generally from 50 to 135 kHz, but it could also be in the HF (13.56 MHz) frequency range or even the UHF frequency bands. When the RFID tag  112  and its associated chip  116  and antenna  114  are placed in the header block  104 , it is important that these components be resistant to body fluids. Over time, body fluids can penetrate through bulk permeability through the header block  104  plastic material. Accordingly, the antenna  114  of the RFID tag  112  must be made of biocompatible material, such as platinum, palladium, niobium and the like. In addition, the RFID chip  116  itself must be either biocompatible or placed within a hermetic package so it is also resistant to body fluids. See U.S. patent application Ser. No. 12/566,223, now U.S. application Pub. No. 2011/0071516, which is incorporated herein by reference. Leadwires  118  and  120  should also be biocompatible up to the point where they are connected to the hermetic seal  130 . It will be apparent to those skilled in the art. that the hermetic seal  130  for the RFID tag  112  could be incorporated within the overall hermetic seal  132  which is coupled to the IS-1 connectors  106 ,  108  and. internal electronic circuits. Leadwires  118  and  120  are routed to leadwires  118 ′ and  120 ′ within the AIMD housing  102  and are connected to the telemetry transceiver  122  which is disposed on a circuit board  110 . 
       FIG. 5  shows that the RFID tag  112  of  FIG. 4  consists of antenna structure  114  and a hermetically sealed package  132  in which the RFID chip  116  is disposed. Terminals  134  and  136  are connected to the RFID tag&#39;s antenna  114 . Leadwires  118  and  120  are routed to the telemetry transceiver  122  which is located inside of the electromagnetically shielded and hermetically sealed AIMD housing  102 . 
     Referring once again to  FIG. 4 , one can see that the antenna  114  of the RFID tag  112  is disposed outside of the hermetic and electromagnetically sealed housing  102  of the AIMD  100 C. In an alternative embodiment, the RFID chip  116  could be disposed inside of the housing  102  of the AIMD, for example, placed on the circuit board  110  adjacent to transceiver chip  122 . In this embodiment, the antenna  114  of the RFID tag  112  would still be disposed outside of the AIMD shielded housing  102  wherein its associated RFID chip and energy storage capacitor  126  are disposed inside the hermetically sealed housing  102 . 
       FIG. 6  is a diagrammatic view illustrating how the RFID activated AIMD telemetry transceiver of the present invention would operate. Shown is an RFID reader/interrogator  124 . It may be a standalone unit, such as a hand-held RFID reader ( FIGS. 8-10 ) or it could be incorporated within or adjacent to the AIMD remote programmer  128  ( FIG. 11 ). A signal or pulse  138  is produced when the RFID reader/interrogator  124  is activated which couples energy to tuned antenna  114  of the RFID tag  112 . This couples energy to terminals  134  and  136  of the RFID chip  116  which activates the RFID chip. The RFID chip  116  stores this energy in a capacitor (not shown) which then transmits a wake-up pulse via terminals  140  and  142  to the telemetry wake-up circuit  144 . The telemetry wake-up circuit  144  then turns power on to the AIMD telemetry transceiver  122 , placing it into an active telemetry mode. Also shown is an optional timer  146  which will turn off the telemetry transceiver  122  and put it back into its sleep mode after a predetermined amount of time. An alternative to the timer  146  is that a second activation of the RFID reader/interrogator  124  would cause the RFID chip  116  to once again be activated so that it sends a toggle pulse back to the telemetry wake-up circuit  144 . This would unlatch or turn off the telemetry transceiver  122  and put it back into its sleep mode. There is a third method of putting the telemetry transceiver  122  back into its sleep mode and that would be by sending a special pulse  148  from the remote programmer  128  which would instruct the telemetry transceiver  122  to go back into its sleep mode. 
       FIG. 7  is an electrical schematic diagram of the system of  FIG. 6 , illustrating the components of the telemetry wake-up circuit  144 . Shown, in this case, is a bipolar junction transistor (BJT) which is also known as a N-P-N transceiver switch  150 . The transistor  150  base  152  receives a signal from the RFID chip  116  from terminals  140  and  142  through leadwires  118  and  120 . This results in a very low voltage drop between the transistor  150  collector C and the emitter E. This effectively connects the telemetry transceiver  122  to voltage source V s  and to the ground reference voltage 0V. This activates the telemetry transceiver  122  which is shown connected to its antenna  158  so that it can receive and transmit information from the AIMD remote programmer  128  ( FIG. 6 ). The voltage source V s  is normally supplied from the AIMD internal battery  154  ( FIG. 3 ). The N-P-N transceiver switch  150  is illustrative of any type of microelectronic switch. These can include a bipolar junction transistor (BJT), a field effect transistor (FET), a metal oxide substrate field effect transistor (MOSFET), a microelectronic mechanical switch (MEMS), a unijunction transistor switch, a silicon-controlled rectifier (SCR) switch, a PIN diode, a P-N junction transistor switch, a P-N-P transistor switch, or any type of N-P-N transistor switch. In general, the RFID chip  116  of the present invention contains at least four terminals. Two of these terminals  134 ,  136  are reserved for connection to the antenna  114  and its associated resonating capacitor  126 . The other two or more terminals  140 ,  142  are for connection to AIMD telemetry transceiver circuits  118 ,  120  in order to provide both wake-up and go back to sleep pulses. 
       FIG. 8  illustrates the operation of the present invention. Shown is a human patient  156  who has an AIMD  100 . In its normal operating mode, the AIMD&#39;s telemetry transceiver circuits would be in a sleep or quiescent low battery drain mode. A signal  138  is transmitted by an RFID reader/interrogator  124 . This pulse  138  is coupled to the RFID tag  112  that is associated with the AIMD  100 . The RFID signal  138  then wakes up the AIMD&#39;s telemetry transceiver  122 . It is at this point that the remote programmer  128  can form a two-way communication link between the AIMD  100  and the programmer  128 . In the case shown in  FIG. 8 , the remote programmer  128  has an antenna  158 , which is an RF antenna. This forms a so-called distance telemetry link between the remote programmer  128  and the AIMD  100 . This typically operates at high frequency. One popular set of frequencies is the MICS band operating in the 402 to 405 MHz frequency range. As previously described, the telemetry transceiver of the AIMD  100  can be put back into its wake-up mode in a number of ways, including an internal timer circuit  146 , receipt of a second type of RFID pulse  138 ′ which will instruct the RFID chip  116  to unlatch the telemetry wake-up circuit thereby putting the telemetry transceiver back into its sleep mode, or even by transmission of a special pulse sequence  160  from the remote programmer  128  which instructs the transceiver  122  to go back into its sleep mode. 
       FIG. 9  is very similar to  FIG. 8 , except that an older style of remote programmer  128  is shown which includes a wand  162  which is placed over the patient&#39;s AIMD  100 . The wand  162  is generally connected through leads  164  to the remote programmer  128 . This type of wanded telemetry involves a close coupled low frequency magnetic link between an antenna in the wand  162  and an associated multi-turn loop antenna associated with the AIMD  100 . Generally, the wand  162  would be placed either very close to or directly on the patient&#39;s chest directly over the AIMD  100 . This is the case for a cardiac pacemaker  100 C. Of course, the AIMD  100  could be located anywhere within the human body in which case the wand  162  would have to be placed over it. The system of  FIG. 9  operates in all ways as previously described in connection with  FIG. 8 . 
       FIGS. 10 and 11  are similar to  FIGS. 8 and 9 , however in this case, the RFID reader  124 , which is illustrated in  FIG. 10 , can be incorporated either within or connected to the AIMD remote programmer  128 . This eliminates the need to have an external portable RFID reader  124 , which would be about the size of a garage door opener. The problem with a small reader around a hospital or operating theater is it is easily misplaced or lost. Accordingly, it is a feature of the present invention that the RFID reader  124  that activates the RFID tag  112  may be built inside of or connected via leads  166  to the AIMD remote programmer  128 . 
     From the foregoing, it will be appreciated that the present invention relates to an RF-activated AIMD telemetry transceiver which includes a telemetry transceiver associated with the AIMD, an RF tag associated with the telemetry transceiver, and a telemetry wake-up circuit electrically disposed between the telemetry transceiver and the RF tag. The RF tag comprises a passive RF chip and an antenna. Preferably, the antenna is biocompatible and the RF chip is disposed within a hermetic package. The telemetry transceiver has an active telemetry mode wherein a telemetry transceiver is powered by the AIMD, and a sleep mode. The telemetry wake-up circuit is responsive to a signal from the RF tag to place the telemetry transceiver into the active telemetry mode. 
     Although several embodiments of the invention have been described in some detail for purposes of illustration, various modifications may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited, except as by the appended claims.