Pacemaker monitoring recorder and malfunction analyzer

A system for playing back and analyzing magnetic tapes on which ECG signals and pacemaker spike signals have been recorded simultaneously for the purpose of monitoring the performance of a pacemaker, in which system the tape is played back at a speed higher than that at which it was recorded until the system recognizes from the played-back signals a manifestation of pacemaker malfunction to generate a command signal in response to which the system reduces the playback speed to facilitate interpretation of the signals by an operator and to facilitate production of a graphic record of the signals, said system comprising in combination:

• an ECG signal channel;
• a separate identical pacemaker signal channel;
• playback means for producing electrical reproduction of the signals stored on the magnetic tape at a playback speed greatly in excess of the speed at which the signals were recorded, for presenting the reproduced signals in said ECG signal channel and in said pacemaker signal channel, and for producing signals at a reduced playback speed in response to said command signal;
• a conditional logic circuit for generating an abnormal bradycardia signal after the occurrence of a QRS complex in the ECG channel unless said conditional logic circuit detects the occurrence of another QRS complex in the ECG signal channel prior to the end of an event window of duration T5 alterable according to playback speed said conditional logic circuit for establishing said window and for altering said duration T5 according to playback speed;
• and
• control means connected to said conditional logic circuit to receive the abnormal bradycardia signal and in response to the abnormal bradycardia signal to generate a command signal and to apply the command signal to said playback means to reduce the playback speed.

A monitoring system for a cardiac patient utilizing a device of the type which generates a prompting signal for initiating a heartbeat comprising:

• ambulatory recording means for sensing and recording both ECG and prompting signals, and
• wherein said recording means includes:
• synthesizing means responsive to sensed prompting signals for producing in response thereto a synthesized signal having a frequency spectrum within the frequency spectrum of ECG signals, and
• means for recording said synthesized signal
• stationary playback means for measuring the time displacement between prompting signals which occur prior to an ECG complex initiated by the prompting signal, and for measuring the time relationship between the occurrence of ECG complexes and subsequent prompting signals as recorded by said means.

An apparatus for use with a magnetic tape recorder having at least one channel capable of recording ECG waveshapes and having at least a pair of ECG electrodes connected to the patient for receiving pacemaker spike signals and for receiving an ECG signal, said apparatus comprising:

• first means for sensing the occurrence of said pacemaker spike signals, said pacemaker spike signal having a frequency spectrum higher than the highest frequency within the spectrum of said ECG signal;
• second means for producing in response to said pacemaker pike signal a synthesized signal whose frequency spectrum lies within the frequency spectrum of said ECG signal;
• and
• third means for coupling said synthesized signal to at least one channel of said magnetic tape recorder,
• whereby said recorder will record the waveshape of said ECG as well as the time displacement of the pacemaker signal.

An apparatus for use with a magnetic tape recorder having at least two identical channels none of which is capable of recording pacemaker spike signals and having at least a pair of ECG electrodes connected to the patient for receiving pacemaker spike signals and for receiving an ECG signal, said apparatus comprising:

• first means for sensing the occurrence of said pacemaker spike signals, said pacemaker spike signals having a frequency spectrum higher than the highest frequency within the spectrum of said ECG signal;
• second means for producing in response to said pacemaker pike signals a synthesized signal whose frequency spectrum lies within the frequency spectrum of said ECG signal;
• and
• third means for coupling said synthesized signal to at least one of said channels of said magnetic tape recorder;
• whereby said recorder will record the waveshape of said ECG as well as the time displacement of the pacemaker signal.

An apparatus for use with a magnetic tape recorder having two identical channels capable only of recording signals in the frequency spectrum of ECG waveshapes and having at least a pair of ECG electrodes connected to the patient for receiving pacemaker spike signals and for receiving an ECG signal, said apparatus comprising:

• first means for sensing the occurrence of said pacemaker spike signals, said pacemaker spike signal having a frequency spectrum higher than the highest frequency within the spectrum of said ECG signal;
• second means for producing in response to said pacemaker pike signal a synthesized signal whose frequency spectrum lies within the frequency spectrum of said ECG signal;
• and
• third means for coupling said synthesized signal to at least one channel of said magnetic tape recorder;
• whereby said recorder will record the waveshape of said ECG as well as the time displacement of the pacemaker signal.

An apparatus for use with a magnetic tape recorder having two identical channels capable only of recording signals in the frequency spectrum of ECG waveshapes and having at least a pair of ECG electrodes connected to the patient for receiving pacemaker spike signals, said pacemaker spike signals being outside said frequency spectrum of said ECG waveshapes, and said electrodes for receiving an ECG signal, said apparatus comprising:

• first means for sensing the occurrence of said pacemaker spike signals, said pacemaker spike signal having a frequency spectrum higher than the highest frequency within the spectrum of said ECG signal;
• second means for producing in response to said pacemaker pike signal a synthesized signal whose frequency spectrum lies within the frequency spectrum of said ECG signal;
• third means for coupling said synthesized signal to at least one channel of said magnetic tape recorder;
• and
• fourth means for coupling said ECG signal to said other one of said at least two channels of said magnetic tape recorder,
• whereby said recorder will record the waveshape of said ECG as well as the time displacement of the pacemaker signal.

In a magnetic tape recording system including separate tracks for ambulatory monitoring of the operation of a pacemaker and of the response of a patient to the pacemaker as revealed by the timing relationship between a pacemaker spike signal generated by the pacemaker and an ECG signal generated by the patient equipped with the pacemaker, an apparatus comprising:

• first means for recording on a magnetic tape in an ambulatory mode the occurrence of a pacemaker spike signal and ECG signal, said pacemaker spike signal having a higher frequency spectrum than the highest frequency spectrum than the highest frequency lying within the frequency of said ECG signal;
• second means for sensing the occurrence of a pacemaker spike signal and ECG signal;
• third means for producing in response thereto a pacer tag signal whose frequency spectrum lies within a predetermined frequency bandwidth, said predetermined bandwidth including the frequency spectrum of said ECG signal;
• fourth means including separate recording channels, said fourth means for recording the pacer tag signal and ECG signal on said separate recording channels and separate tracks on said magnetic tape, said fourth means characterized by said predetermined bandwidth, only signals having a frequency within said predetermined bandwidth being recorded on said separate tracks;
• fifth means for stationary operation for playing back the recorded magnetic tape at a selected one of a plurality of speeds higher than the recording speed at which it was originally recorded;
• sixth means for determining during the high speed playback a timing relationship between the ECG signal and the pacer tag signal;
• seventh means for selecting on the basis of the timing relationship of the ECG signal to the pacer tag signal one of several different output signals indicative of the operation of the pacemaker and of the response of the patient to the pacemaker
• wherein said fifth means further comprises:
• a pacemaker channel;
• an ECG signal channel;
• an analysis module receiving occasional pacemaker spikes in said pacemaker signal channel and receiving occasional QRS complexes in said ECG signal channel, the signals on the two channels being correlated in time, by said analysis module, said analysis module producing signals indicative of the operation of the pacemaker, said analysis module including a conditional logic circuit for generating an abnormal bradycardia signal after the occurrence of a QRS complex in the ECG signal channel contingent on the failure of receipt of a signal in said ECG channel within variable time interval T5 after receipt of a signal in said pacemaker channel, said variable time interval T5 being dependent on playback speed of said fifth means, said signal being indicative of a subsequent QRS complex in the ECG signal channel,
• whereby proper operation of said pacemaker in response to heart activity is monitored and verified.

An apparatus for use with a magnetic tape recorder having two identical channels for recording signals indicative of the operation of a pacemaker and the response of a patient to a pacemaker, at least a pair of ECG electrodes connected to the patient for receiving pacemaker spike signals and for receiving an ECG signal, said apparatus comprising:

• first means for sensing the occurrence of said pacemaker spike signal, said pacemaker spike signal having a frequency spectrum higher than the highest frequency within the spectrum of said ECG signal;
• second means for producing in response to said pacemaker spike signal a synthesized signal whose frequency spectrum lies within the frequency spectrum of said ECG signal;
• third means for coupling said synthesized signal to one channel of said magnetic tape recorder;
• and
• fourth means for coupling said ECG signal to said other identical one of said channels of said magnetic tape recorder.