Abstract:
A programmer for implantable stimulation devices and surface ECG system in wireless communication with each other. A self-powered ECG monitor with conventional surface electrodes transceives signals from and to a programmer provided with a radio frequency transceiver to eliminate hardwiring between the surface electrodes and the programmer. The system reduces the need for supply line frequency filtering and isolation circuitry to protect against high voltage defibrillation shocks.

Description:
FIELD OF THE INVENTION 
     The present invention relates to the field of cardiac monitoring devices and, in particular, to a combined programmer for implantable cardiac devices and a surface ECG system with a wireless communication capability with the programmer. 
     BACKGROUND OF THE INVENTION 
     The ongoing clinical care provided to patients with implantable cardiac device systems often includes the use of surface electrocardiograms (ECG). An ECG is a highly useful diagnostic aid for clinicians for the study of heart rate and rhythm. The ECG indicates the propagation of low amplitude electrical signals, commonly referred to as the cardiac impulse, across the myocardium giving information about depolarization and repolarization characteristics of the heart. 
     An ECG typically receives signals from a plurality of electrodes (3, 5, and 12 are common numbers) that are placed on the patient&#39;s skin surface. The ECG monitors voltage signals appearing between various pairs of the electrodes and performs a vector analysis of the resultant signal pairs to prepare various two-dimensional voltage-time graphs indicative of internal cardiac activity. Surface ECG refers to placement of electrodes on the surface, or skin, of the patient as opposed to directly to cardiac tissue which obviously requires an invasive procedure. 
     A programmer is a device that enables a clinician to telemetrically communicate with an implantable cardiac device such as pacemaker or defibrillator. Implantable devices often monitor and record a variety of internal physiological parameters of the patient and are often provided with a telemetry system to telemetrically transmit those measured and recorded parameters outside the patient&#39;s body. Implantable devices are also often capable of receiving telemetric signals to induce the device to set or change a variety of operational parameters of the device as well as to select among the physiological parameters that the device monitors and records. These parameters are often desirably changed during the implantation period to adjust the therapy provided and/or physiological parameters monitored in order to provide the attending clinician with different information or to adapt the therapy to a more efficacious regimen. It is highly desirable to set these parameters without the expense and health risks to the patient of an invasive procedure. The programmer enables the attending clinician to perform these tasks in a non-invasive, telegraphic manner. 
     A surface ECG is often used along with the programmer as the surface ECG provides additional information above that provided by the internal measurements obtained by the implantable device. The programmer is typically adapted to obtain a surface ECG through a special cable that generally interconnects the programmer to electrodes placed on the patient. As the programmer is thus electrically coupled to the patient, it is subject to exposure to electromagnetic interference (EMI) that may surround the interconnection. The programmer is also potentially subject to large common-mode 50/60 Hz (supply line frequency) signals that are picked up by the patient&#39;s body. Both EMI and common-mode signals degrade the accuracy of the ECG signal. 
     An additional concern in certain applications where defibrillation may be applied to the patient is the relatively large amplitude (hundred volt to kilovolt range) shocks that are typically applied to interrupt the fibrillation. These high voltage shocks can be conducted through other cabling interconnecting the patient and other equipment such as programmers. Accordingly, the front-end electronics (those directly in contact with the cabling) of the programmer generally require voltage protection adequate to prevent damage from up to 5000V that may be applied to the patient as defibrillation. The inclusion of such protection circuitry increases the cost and complexity of programmers. 
     The interconnection cable employed in prior art programmers with surface ECG systems presents some further difficulties in use for the clinician and for the patient. The cable is physically attached to the patient and impairs their movement in bed and can become entangled with bedding, I.V. tubes, etc. The cables also physically interconnect the programmer to the patient and thus present a physical obstacle that must be avoided by people moving in the room. The cables present a tripping hazard as well as a potential cause of upset and damage to the programmer or other devices that may be placed on tables or carts. 
     Another disadvantage of present programmer/ECG systems is that the clinician must physically connect the programmer to surface electrodes with the interconnection cable each time he visits a new patient. Often an individual programmer is not available for each patient due to cost considerations and the clinician must move a single programmer with him as he visits patients. It can be appreciated that disconnecting and reconnecting the cables each time a clinician visits a patient consumes the doctor&#39;s valuable time as well as presents a cause of wear and tear on the cables and connectors. 
     From the foregoing it can be appreciated that there is an ongoing need for a programmer/ECG system that reduces the need for obtrusive and hazardous cables. There is also a need for a system that facilitates movement of the clinician from patient to patient in different locations and maintains the functionality of programmers in communication with surface ECGs without the expense of providing a dedicated programmer at each patient location. 
     SUMMARY OF THE INVENTION 
     The aforementioned needs are satisfied by the invention which, in one aspect, is a system that communicates with and programs an implantable stimulation device and obtains a surface ECG signal, the system comprising a wireless ECG monitoring system including an electrode system adapted to adhere to a patient&#39;s skin in desired locations and provide a plurality of electrode signals, and an ECG monitor adapted to be worn by the patient and coupled to the electrode system so as to receive the plurality of electrode signals, the ECG monitor having circuitry to transmit a plurality of surface ECG signals and a programmer including a first telemetry circuit that transceives programming signals and data with the implantable stimulation device, a second telemetry circuit that receives the plurality of ECG signals from the wireless ECG monitoring system, and a display system that graphically displays the received surface ECG signals. 
     These aspects of the invention can also include the feature wherein the system includes a sensing system that senses each electrode signal and a signal processor that processes each electrode signal into at least one of a Lead I, Lead II, Lead III, aV R  Lead, an aV L  Lead, an aV F , or a V Lead or wherein the wireless ECG monitoring system further includes a sensing system that senses each electrode signal and a signal processor that processes each electrode signal into at least one of a Lead I, Lead II, or Lead III. In the later aspect, the signal processor can further process each electrode signal into one of an aV R  Lead, an aV L  Lead, an aV F , or a V Lead. 
     The invention also includes the aspect wherein the ECG monitoring system further includes a plurality of switches connected to the electrode signal to enable selection among the plurality of electrode signals. In this aspect, the plurality of switches can be electronic and selection among the plurality of electrode signals occurs in response to control signals from the programmer or the plurality of switches are manually operated to select among the plurality of electrode signals. 
     Another aspect of the invention is wherein the first and second telemetry links utilize a first and second channel respectively for independently processing the programming signals and the data signals with the implantable stimulation device from the plurality of surface ECG signals from the wireless ECG monitoring system. Under this aspect, the first and second channels can comprise first and second frequency channels, first and second time division channels, or first and second modulation channels. This aspect can further include wherein at least one of the first and second telemetry circuits operate in the 900 MHz band. 
     An additional aspect of the invention is a monitoring system for an implantable cardiac stimulation device, the monitoring system comprising a programmer that includes a telemetry receiver so as to be able to receive signals from an implantable cardiac stimulation device, wherein the programmer includes a display that displays information about the performance of the implantable device and a surface monitoring system that includes at least one electrode that is adapted to be positioned on the body of the patient so as to produce a surface signal indicative of the patient&#39;s heart function, wherein the surface monitoring system includes a wireless transmitter that transmits signals to the programmer indicative of the surface signal and wherein the programmer is further adapted to display the surface signal on the display to permit simultaneous evaluation of the information about the performance of the implanted device provided via the telemetry receiver and the surface signal. 
     A particular aspect therein is that the surface signal comprises an ECG and can further comprise at least one of a Lead I, Lead II, Lead III, aV R  Lead, an aV L  Lead, an aV F , or a V Lead. 
     Yet another aspect is that the programmer, the implantable device, and the surface monitoring system each include a telemetry transceiver such that the programmer, the implantable device, and surface monitoring system can each both send and receive wireless signals. This aspect can include wherein communication between the programmer and the implantable device occurs on a first RF channel and communication between the programmer and the surface monitoring system occurs on a second RF channel and further that at least one of the first and second RF channels operate in the 900 MHz band. 
     Further aspects of the invention include that the system comprises a plurality of electrodes. Additionally, the surface monitoring system can select from among the plurality of electrodes to send signals to the programmer indicative of the selected signals. Further, signals from the programmer induce the surface monitoring system to select signals from among the plurality of electrodes to send signals to the programmer indicative of the selected signals or the system further comprises a plurality of switches connected to the plurality of electrodes wherein the switches are manually operated to select among the plurality of electrodes. 
     Alternatively, the surface monitoring system sends signals corresponding to all of the plurality of electrodes to the programmer and the programmer selects from among the signals corresponding to the plurality of electrodes to determine the surface signal to display. 
     The invention is also a therapeutic stimulation and monitoring system for a patient&#39;s heart comprising an implantable cardiac stimulation and physiological parameter monitoring device, a programmer adapted to transceive wireless signals with the implantable device so as to induce the implantable device to alter the therapeutic stimulation and monitored physiological parameters provided and to transmit signals indicative of the monitored physiological parameters to the programmer, and means for monitoring surface signals of the patient indicative of cardiac activity including means for transceiving wireless signals with the programmer so as to provide the programmer with signals indicative of the surface signals of the patient and to receive signals inducing the monitoring means to alter the configuration of the surface signal provided to the programmer. 
     Particular aspects thereunder include wherein the programming means further comprises display means for displaying signals indicative of the surface signals of the patient. The surface signals can comprise a surface electrocardiogram that can comprise at least one of a Lead I, Lead II, Lead III, aV R  Lead, an aV L  Lead, an aV F , or a V Lead. 
     A further aspect of the invention is wherein the monitoring means provides the programmer with signals selected from among a plurality of the surface signals. Here the monitoring means can select among the plurality of surface signals in response to wireless signals from the programmer or the therapeutic stimulation and monitoring system can further comprise a plurality of switches that are manually actuated to select among the plurality of surface signals. 
     In addition, the implantable device and the programmer can communicate via first wireless communication means and the programmer and the monitoring means can communicate via second wireless communication means. This can occur such that at least one of the first and second wireless communications means operate in the 900 MHz band. These and other objects and advantages will be more apparent from the following description taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a high-level block diagram of an implantable stimulation device programmer and surface ECG system with wireless communication having a five electrode configuration; 
         FIG. 2  illustrates a surface ECG unit with wireless communication capability and with three electrodes adhered to a patient; 
         FIG. 3  is a perspective view of an implantable cardiac device programmer with wireless communication with a surface ECG unit; 
         FIG. 4  is a screen capture of one embodiment of the system of  FIG. 1 ; 
         FIG. 5  is a circuit diagram of one embodiment of the system of  FIG. 1 ; 
         FIG. 6  is a table of one embodiment of the control logic for achieving various lead configurations in the system of  FIG. 1 ; and 
         FIG. 7  is a functional block diagram of one embodiment of the programmer. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will now be made to the drawings wherein like numerals refer to like parts throughout.  FIG. 1  illustrates a programmer for implantable cardiac devices and surface electrocardiogram (ECG) monitor with wireless communication system  100  referred to hereafter as “system  100 ” for brevity. The system  100  enables a clinician to program and retrieve information from an implantable stimulation device (not shown) via a first telemetric link  105  and to receive and control surface ECG signals in a wireless fashion from the patient via a second telemetric link  106  in a manner that will be described in greater detail below. 
     The system  100  comprises an ECG monitor  102  that monitors surface ECG signals of a patient&#39;s body and selectively transmits those signals to a remote programmer  104  via the second telemetric link  106 . The second telemetric link  106  reduces the need for the hardwiring of the prior art between an ECG monitor and a programmer while enabling the surface ECG monitor  102  and the programmer  104  to remain in communication with each other. 
     The surface ECG monitor  102  comprises a plurality of electrodes  110 ,  111 . In one embodiment ( FIG. 1 ), the ECG monitor  102  comprises 5 electrodes  110   a – 110   e  and in another embodiment ( FIG. 2 ) the ECG monitor  102  comprises 3 electrodes  111   a – 111   c . However, other embodiments can comprise alternative numbers of electrodes  110 ,  111 . The electrodes  110 ,  111  monitor electrical activity on the skin surface of a patient indicative of internal cardiac activity in a known manner. The electrodes  110 ,  111  are placed and secured to a patient&#39;s body in a manner well understood in the art. 
     In one embodiment, the electrodes  110  are unitized pieces including a sensor section placed on the patient&#39;s body and a fixedly attached conductive line. In another embodiment, the electrodes  111  are separable assemblies including a sensor section removably attached to a conductive line as illustrated in  FIG. 2 . The electrodes  110 ,  111  are commercially available. 
     As shown in  FIG. 2 , the ECG monitor  102  also comprises a transceiver  112  providing the second telemetric link  106  with the programmer  104 . The transceiver  112  is a self-powered radio transceiver and, in this embodiment, operates in the 900 MHz band. However, other frequencies can be employed in alternative embodiments of the transceiver  112  without detracting from the scope of the invention. It will be understood by one of skill in the art that the frequencies utilized by the transceiver  112  should be chosen so as to minimize interference with other electronic devices in use in the vicinity of the system  100 . The transceiver  112  selectively transmits signals monitored by the electrodes  110 ,  111  to the programmer  104 . In one embodiment, the transceiver  112  also receives signals from the programmer  104  to vary the electrodes  110 ,  111  from whose measurements the transceiver  112  sends to the programmer  104 . 
     In one embodiment, the ECG monitor  102  includes a switch ( FIG. 2 )  114 . The switch  114  is interposed between the electrodes  111   a – 111   c  and the transceiver  112  so as to selectively connect or disconnect the individual electrodes  111   a – 111   c  from the transceiver  112  so as to enable selection of the electrodes  111   a – 111   c  whose signals are passed to the transceiver  112 . This aspect facilitates ready selection of a number of different lead configurations by the clinician. In one embodiment, the switch  114  is a manually operated switch, however, in other embodiments, the selection of the electrodes  110 ,  111  is performed electronically in response to telegraphic signals from the programmer  104  in a manner that will be described in greater detail below with reference to  FIG. 5 . 
       FIG. 3  illustrates one embodiment of the programmer  104 . The programmer  104  comprises a display screen  120 , at least one input device  122 , and a removable storage device  124 . The display screen  120  provides information relating to the operation of the ECG monitor  102  and the implantable cardiac device in a known manner. An example of one embodiment of the information provided by the display screen  120  is illustrated in  FIG. 4  and will be described in greater detail below. The input device  122  is adapted to enable a user to input commands to the programmer  104  in a known manner. The input device  122  in the embodiment illustrated in  FIG. 3  comprises a keyboard of a type well known in the art, however, the input device  122  can also comprise touch screens, touch mouse pads, speech recognition systems, or other input mechanisms in alternative embodiments of the invention. 
     The removable storage device  124  enables a user to store information relating to a patient&#39;s condition and treatment in a removable, non-volatile manner. In one embodiment, as illustrated in  FIG. 3 , the removable storage device  124  comprises a standard 3½″ disk drive and removable disks of types well known in the art. In other embodiments, the removable storage device  124  comprises a read/write CD-ROM drive and rewritable CDs and/or flash memory systems also of types well known in the art. Additional features and functions of the programmer  104  will be described in greater detail below with reference to  FIG. 4  and  FIG. 7 . 
       FIG. 4  illustrates a screen capture of one embodiment of the display screen  120  of the programmer  104 . The display screen  120  presents a visual representation of the underlying cardiac activity as sensed by the system  100  as an ECG waveform  116 . In this embodiment, the ECG waveform  116  can be displayed as a real-time, dynamic scrolling display or a time slice of the ECG waveform  116  can be frozen to enable a clinician to investigate in greater detail a representative sample of the ECG waveform  116 . As shown in  FIG. 4 , in this embodiment, the display  120  of the programmer also provides a plurality of user selectable controls for the programmer  104 . 
     As illustrated in  FIG. 4 , the programmer  104  is set to a basic parameters option. In this option, certain basic sensed parameters, such as the base rate, the AV delay, PV delay, and others, are displayed. The programmer  104  of this embodiment also provides the ability to alter/set operational parameters of the implantable device, such as ventricular autocapture, which, in the embodiment illustrated, is selected “Off”. It can be further seen that the programmer  104  provides additional extended parameter display, more detailed patient data, and sensor parameter information and control. This aspect is useful to a clinician in remotely setting parameters of the sensor portions of the implantable device, such as threshold levels in a non-invasive manner via, the first telemetric link  105 . The programmer  104  also includes the capability, in certain embodiments, to select the electrodes  100 ,  111  that pass their respective signals, via the transceiver  112 , to the programmer  104  in a manner that will be described in greater detail below. 
     It will be appreciated that the specific functionalities and information provided by the programmer  104  can vary among different applications. It is therefore preferred that the programmer  104  be programmable and user-customizable. For example, as illustrated in  FIG. 4 , the programmer  104  of this embodiment has provision for both temporary and permanent programming as well as automated tests and diagnostic functions. The programmable aspects of the programmer  104  can include provisions for interfacing with different versions of implantable medical devices, operating in different radio frequencies, and storing data specific to different patients. 
       FIG. 5  illustrates in greater detail a circuit block diagram of the surface ECG monitor  102 . The surface ECG monitor  102  monitors and selectively transmits a surface ECG signal as sensed by a plurality of electrodes  110 ,  111  in a plurality of lead configurations. In this embodiment, the surface ECG monitor  102  comprises the 5 electrodes  110   a – 110   e  with electrode  110   a  designating the C (center) electrode,  110   b  designating the LA (left arm) electrode,  110   c  designating the RA (right arm) electrode,  110   d  the LL (left leg) electrode, and  110   e  the RL (right leg) electrode. As previously described, the electrodes  110   a – 110   e  sense and conduct electrical signals from the patient&#39;s skin surface indicative of underlying cardiac activity. Proper placement and attachment of the electrodes  110   a – 110   e  on the patient for the C, LA, RA, LL, and RL positions is well understood by one of ordinary skill in the art. 
     The surface ECG monitor  102  also comprises, in this embodiment, 4 amplifiers  130   a – 130   d . Each of the electrodes  110   a – 10   d  is connected to the non-inverting input of each of the amplifiers  130   a – 130   d  respectively. The inverting input of each of the amplifiers  130   a – 130   d  is connected to the outputs of each of the amplifiers  130   a – 130   d  respectively. The output of each of the amplifiers  130   a – 130   d  is also connected to one pole of a switch  132   a – 132   d  respectively. The switches  132   a – 132   d  facilitate selection by a clinician of which of the electrodes  110   a – 110   d  pass their signal through the surface ECG monitor  102  and thus on to the programmer  104 . The opposite poles of the switches  132   a – 132   d  are commonly connected to the non-inverting input of an amplifier  134 . 
     The surface ECG monitor  102  also comprises switches  132   e – 132   g . One pole of each of the switches  132   e – 132   g  is connected to the output of the amplifiers  130   b – 130   d  respectively. The opposite poles of each of the switches  132   e – 132   g  are connected in parallel via, in this embodiment, a 30.1 kΩ resistor, in common to the inverting input of the amplifier  134 . 
     The output of the amplifier  134  is connected to a high pass filter  135 . The high pass filter  135  filters out DC offsets due to electrode-skin interfaces and the amplifier A 5   134 . In one embodiment, the high pass filter  135  comprises a capacitor, C 1  and resistor, R 6  as shown in  FIG. 5 . In one particular embodiment, a value of C 1  of 0.33 μF and a value of R 6  of 10 MΩ gives a corner frequency of f=½πRC=0.05 Hz. 
     In this embodiment, a switch, S 8   136  is also provided. The switch, S 8   136 , in this embodiment, can be momentarily closed by the programmer  104  to speed up the baseline coming to zero. The momentary closure of switch S 8   136  will quickly charge the capacitor C 1  of the high pass filter  135 , thus removing any DC offset. The output of the amplifier  134  is connected, via the high pass filter  135  and the switch  136 , to the input of a low pass filter (LPF)  138 . 
     The output of the LPF  138  is connected to the input of an analog-to-digital (A/D) converter  140 . The A/D  140  converts the analog multiplexed signals received from the electrodes  110   a – 110   e , as selected by the switches  132   a – 132   g  and digitizes these signals in a well understood manner. The digitized surface ECG signal is then sent from the output of the A/D  140  to a radio-frequency (RF) transmitter  142 . The RF transmitter  142  transmits the digitized surface ECG signals via an antenna  144  to the programmer  104  in a manner well understood by one of ordinary skill in the art. 
     In this embodiment, the surface ECG monitor  102  also comprises a radio frequency (RF) receiver  146  in communication with the antenna  144 . The RF receiver  146  receives radio-frequency transmissions from the programmer  104  via the antenna  144  and passes these signals to a decoder  150 . In this embodiment, the decoder  150  is an 8 bit digital-to-analog (D/A) converter. In this embodiment, the 8(a–h) digital outputs of the decoder  150  are connected to the switches  132   a – 132   g  and  136 , respectively, such that setting/clearing the various outputs of the decoder  150  can close/open each of the switches  132   a – 132   g  and  136  individually depending on the signal received by the RF receiver  146 . As previously mentioned, according to this aspect of the invention, each of the switches  132   a – 132   g  can be remotely, telegraphically controlled, such as by the programmer  104 , to vary which of the electrodes  110   a – 110   e  have their respective signals processed by the surface ECG monitor  102  and thus transmitted by the RF transmitter  142 . 
     Thus, according to this aspect, a clinician or other user can alter the lead configuration provided by the 5 electrodes  110   a – 110   e  directly with the programmer  104  without physical contact with the patient following initial attachment of the electrodes  110   a – 110   e  via the second telemetric link  106 . Thus, the clinician can readily select among the available lead configurations without physically detaching or disconnecting the electrodes  110   a – 110   e  attached to the patient. It will be appreciated that, in alternative embodiments, signals from all of the electrodes  110 ,  111  are transmitted by the surface ECG monitor  102  and the programmer  104  selects locally from among the electrode  110 ,  111  signals to generate the ECG waveform  116  for the display screen  120 . 
     The table of  FIG. 6  shows the lead configurations of one embodiment with the corresponding position of the switches  132   a – 132   g . For one example, the aVF lead configuration is selected when switches  132   d – 132   f  are closed (on) so as to conduct the signal from the electrode  110   d , i.e. the LL electrode, to the non-inverting input of the amplifier  134  as well as the combined signals from the electrodes  110   b  and  110   c , i.e. the LA and RA electrodes, to the inverting input of the amplifier  134 . The other switches  132   a ,  132   b ,  132   c , and  132   g  are open and their respective electrode  110  signals are opened from the inputs of the amplifier  134 . The other lead configurations I, II, III, aVR, aVL, V, and null provided by other switch  132   a – 132   g  positions, as presented in  FIG. 6 , as well as selection of appropriate lead configurations for a given clinical circumstance will be well understood by one of ordinary skill in the art following the above example. 
     Lead I is defined as the RA signal as the −input and the LA signal as the +input. Lead II is defined as the RA signal as the −input and the LL signal as the +input. Lead III is defined as the LA signal as the −input and the LL signal as the +input. The aVR lead is defined as the (LA+LL)/2 signal as the −input and the RA signal as the +input. The aVL lead is defined as the (RA+LL)/2 signal as the −input and the LA signal as the +input. The aVF lead is defined as the (RA+LA)/2 signal as the −input and the LL signal as the +input. The V lead is defined as the (RA+LA+LL)/3 signal as the −input and the C signal as the +input. 
       FIG. 7  is a functional block diagram of one embodiment of the programmer  104  in greater detail. As previously mentioned, the programmer  104  receives surface ECG signals from the ECG monitor  102  via the second telemetric link  106  and displays them as the ECG waveform  116  on the display  120 . The programmer  104  also receives user commands via the input device(s)  122  and induces the ECG monitor  102  and/or the implantable device to perform specified actions via the first telemetric link  105 . 
     In this embodiment, the programmer  104  comprises an internal bus  152  and a central processing unit (CPU)  154 . The CPU  154  interfaces with other components of the programmer  104  via the internal bus  152  and directs their operation in a manner well understood in the art. The programmer  104  also comprises read-only-memory (ROM)  156 , random-access-memory (RAM)  160 , and a hard drive  162 . The ROM  156 , RAM  160 , and hard drive  162  are in communication with the internal bus  152  and provide the programmer  104  short term memory and long term, non-volatile storage capability in a well known manner. As previously mentioned, the programmer  104  comprises a storage device which can comprise the floppy drive and diskette as illustrated in  FIG. 3  and the CD-ROM and drive as illustrated in  FIG. 7  as well as other non-volatile storage systems, such as flash memory. 
     The programmer  104  also optionally includes a speaker  164 , printer  166 , parallel port  170 , and/or serial port  172 . The speaker  164  is adapted to provide auditory alerts and indicators and the printer  166  is adapted to provide a written record of data, such as a portion of the ECG waveform  116 , or a summary of the information provided by the display  120 , such as patient data. The parallel port  170  and the serial port  172  are adapted to interface with other electronic devices in a parallel or serial manner, respectively. The exact manner and format of the parallel or serial communication performed by the parallel  170  and serial  172  ports, respectively, may vary in different applications. 
     As previously mentioned, the display  120  presents a user with visual information. The display  120  can also optionally comprise a touch-screen  120 ′ to enable the display  120  to operate at least partially as an input device  122 . The programmer  104  also preferably includes the user-customizable functionality of custom keys  121 . The custom keys  121  enable a user to program frequently used or personal preference functions of the programmer  104 . In certain embodiments, the custom keys  121  are embodied in the touch screen  120 ′ of the display  120 . In other embodiments, the custom keys  121  are user definable keys or key combinations of the input device  122 . 
     The programmer  104  in certain embodiments also transceives analog signals. In certain embodiments, the analog communication occurs via an analog output circuit  174  via hardwired analog outputs. In other embodiments, the first telemetric link  105  is adapted to transceive analog format signals in a well known manner. 
     The programmer  104  also comprises a telemetry CPU  176 . The telemetry CPU  176  is in communication with the CPU  154  via the internal bus  152 . The telemetry CPU  176  directs and monitors the operation of the telemetric links  105 ,  106 . 
     Although  FIG. 7  illustrates two separate telemetry circuits in the programmer  104  under control of the telemetry CPU  176  providing the first  105  and second  106  telemetric links with the implantable device and the surface ECG monitor  102 , the first and second telemetric links  105 ,  106  can also comprise different RF channels, different communication formats such as amplitude modulation (AM), frequency modulation (FM), frequency shift keying (FSK), quadrature phase shift keying (QPSK), time multiplexing or time slotted communications, such as time division multiple access (TDMA), or packet addressing in a variety of implementations well known in the art in alternative embodiments of the system  100 . 
     Although the preferred embodiments of the present invention have shown, described and pointed out the fundamental novel features of the invention as applied to those embodiments, it will be understood that various omissions, substitutions and changes in the form of the detail of the device illustrated may be made by those skilled in the art without departing from the spirit of the present invention. Consequently, the scope of the invention should not be limited to the foregoing description but is to be defined by the appended claims.