Recorder with patient alarm and service request systems suitable for use with automatic implantable defibrillator

• US 4,295,474 A
• Filed: 10/02/1979
• Issued: 10/20/1981
• Est. Priority Date: 10/02/1979
• Status: Expired due to Term

• Current Assignee: Ventritex Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Johns Hopkins University
• Inventors: Fischell, Robert E.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US06/081,167
• Time in Patent Office: 749 Days
• Field of Search: 128/695-697, 128/710-712, 128/419 D, 128/419 P, 128/419 PG, 128/419 PS, 128/419 PT, 346/33 ME
• US Class Current: 600/510
• CPC Class Codes: A61B 5/333 Recording apparatus specially adapted therefor
• CPC Class Codes: A61B 5/336 Magnetic recording apparatus
• CPC Class Codes: A61N 1/3702 Physiological parameters A61N1/365 takes precedence; evoked response A61N1/371
• CPC Class Codes: A61N 1/37223 Circuits for electromagnetic coupling
• CPC Class Codes: A61N 1/37258 Alerting the patient
• CPC Class Codes: A61N 1/3925 Monitoring; Protecting

Abstract

The invention relates to a system and apparatus, particularly adapted for use with an automatic implantable defibrillator, for monitoring electrocardiagram (ECG) data signals to provide a continuously updated recording of the ECG data. The proposed recorder responds to the operating condition of the automatic implanted defibrillator device and places into storage, for subsequent readout by the patient'"'"'s doctor, ECG data both immediately preceding the onset of a ventricular fibrillation episode and also during the subsequent defibrillation activity, when one or more high energy electrical impulses are applied to the patient'"'"'s heart. Selected other data regarding operation of the implanted defibrillator and pertinent to the doctor'"'"'s evaluation of the patient'"'"'s condition as well as the efficacy of the defibrillator unit, are also recorded by the proposed apparatus for subsequent readout. In addition, the proposed recording apparatus operates to automatically alert the patient that ventricular fibrillation has been detected and that defibrillation is to be attempted, so that appropriate precautions may be taken. Moreover, following defibrillation, the patient is alerted in a distinctive manner that defibrillation has occurred and that a physician should be contacted, as soon as possible.

Claims

1. A recorder system, adapted for use with an automatic defibrillator system responsive to a patient'"'"'s electrocardiagram (ECG) data and capable of detecting the occurrence of abnormal cardiac activity and render effective automatically in response thereto to generate and apply one or more defibrillation electrical impulses to the patient'"'"'s heart intended to return the heart to normal functioning, said recorder system being responsive to the patient'"'"'s ECG data and comprising, in combination,

means for sampling and converting said ECG data from analog to digital form,

first and second ECG data digital storage means,

means for registering the occurrence of said abnormal cardiac activity as detected by said automatic defibrillator system,

storage control means controlled by said occurrence registering means responsive to the occurrence of said abnormal cardiac activity for selectively rendering effective said first and second ECG data storage means to store ECG digital data occurring respectively for a first time period just prior to the occurrence of said abnormal cardiac activity or for a second time period encompassing the application of said defibrillation impulse(s) by said automatic defibrillator system,

time registration means controlled by said occurrence registering means responsive to the occurrence of said abnormal cardiac activity for registering as a digital code the time of occurrence of said abnormal cardiac activity,

first counting means responsive to the generation of each defibrillation impulse by said automatic defibrillation system for registering as a digital code a count of the number of said defibrillation electrical impulses generated by said automatic defibrillator system,

second counting means responsive to said occurrence registering means for registering as a digital code a count of the number of occurrences of said abnormal cardiac activity, and

readout control means operable upon command for reading out

(a) the ECG digital data stored in each of said first and second storage means,

(b) the digital code time registration of said time registration means, and

(c) the digital code counts of each of said first and second counting means.

2. The recorder system specified in claim 1 wherein:

said means for sampling and converting the patient'"'"'s analog electrocardiogram (ECG) signal generates a succession of corresponding digital data words, and

said first and second ECG digital data storage means includes memory means subdivided into a first portion updated continuously to store the digital code words corresponding to a preselected first ECG interval prior to the operation of said defibrillator, and a second portion to store the digital code words corresponding to a second preselected ECG interval encompassing the operation of said defibrillator and indicating the patient'"'"'s response to said defibrillation electrical impulse(s).

3. The recorder system specified in claim 1 further including means rendered effective upon the occurrence of said abnormal cardiac activity to provide a first alarm warning signal to the patient indicating said occurrence and rendered effective following operation of said automatic defibrillator to provide a second service request warning signal to the patient indicating that said automatic defibrillator has operated.

4. The recorder system specified in claim 3 wherein said first and second warning signals each have unique characteristics rendering them distinguishable from one another by the patient.

5. The recorder system specified in claim 4 including means for repeating said second warning signal at selected intervals for continuously reminding the patient to seek medical assistance.

6. The recorder system specified in claim 3 further including means controlled by the patient'"'"'s physician for selectively commanding said first alarm and second service request warning signals, as desired.

7. The recorder system specified in claim 1 further including means to reset each of said time registration means and said first and second counting means following readout.

8. The recorder system specified in claim 1 wherein said recording system is implanted and further including communications means comprising:

an external transmitter means for transmitting a readout command

an implanted means for receiving said readout command to initiate operation of said read out control means,

an implanted transmitter means for transmitting a digital signal including said read out ECG digital data, said digital code time registration and said digital code counts, and

an external receiver means for receiving said transmitted digital signal.

9. The recorder system specified in claim 8 wherein said recorder system further includes means for specially encoding the transmission to said external receiver means for each particular patient.

10. The recorder system specified in claim 8 wherein said recorder system further includes means rendered effective upon transmission of said readout command to apply a predetermined digital code to said internal transmitter means to initiate transmission by said implanted transmitter means of a predetermined transmission pattern preceding the transmission of said stored data for synchronizing said external receiver means to said data transmission.

11. The recorder system specified in claim 8 further including means for controlling said internal transmitter means to transmit said data at least twice each time a readout command is transmitted.

12. The recorder system specified in claim 11 including means to control said internal transmitter means to continuously transmit said data so long as a readout command is continuously transmitted.

13. The recorder system specified in claim 8 further including multiplexer means connected to said implanted transmitter means for multiplexing said ECG digital data, said digital code time registration and said digital code counts into a serial data output bit stream for transmission.

14. The recorder system specified in claim 13 further including:

clocking means for establishing the data bit rate for said data output bit stream,

means responsive to said clocking means for generating a predetermined bit pattern, and

means rendered effective upon transmission of a readout command to initiate transmission of said predetermined bit pattern prior to transmission of said serial data output bit stream for synchronizing said external receiver means to the data bit rate of said data output bit stream.

15. The recorder system specified in claim 14 further including implantable code generator means for producing a code signal distinctively identifying the particular patient in which the recorder system is implanted, and means for incorporating said patient identifying code signal into said serial data output bit stream.

16. The recorder system specified in claim 13 further including means for adding to said serial data output bit stream a digital code identifying the particular patient whose ECG signal is represented by said serial data output bit stream.

17. A recorder system responsive to a selected physiological signal of a patient for monitoring, storing and reading out, on command, data regarding a particular physiological functioning represented by said physiological signal for that patient, comprising:

means for sampling and converting said physiological signal from an analog form into a corresponding digital data signal format,

addressable memory means for storing the digital data signal, said memory means being divided into first and second storage portions,

means for repeatedly addressing the first storage portion of said memory prior to the occurrence of a preselected physiological event to continually update the digital data stored in said first storage portion,

means for registering the occurrence of said preselected physiological event,

means controlled by said registration means rendered effective upon the occurrence of said preselected physiological event to hold the most recent digital data then stored in said first storage portion corresponding to a first predetermined interval preceding said event,

means controlled by said registration means rendered effective upon the occurrence of said preselected physiological event for thereafter addressing the second storage portion of said memory to store the digital data corresponding to said physiological signal during a second predetermined interval following said event,

readout control means operable upon command for reading out the digital data stored by said first and second storage portion of said memory,

means for commanding said readout control means, and

patient identification generator means responsive to said readout control means for annexing a code to said digital data during readout uniquely identifying the particular patient.

18. The recording system specified in claim 17 wherein said converting means converts said physiological signal from an analog form to a succession of multiple bit digital data words and wherein said addressable memory means comprises a plurality of random access memory (RAM) stages.

19. The recording system specified in claim 17 wherein said commandable readout control means includes multiplexing means for arranging the stored digital data bits into a serial data output bit stream during readout.

20. The recording system specified in claim 19 wherein said sampling and converting means, said memory means and said multiplexing means of the recording system are implanted in the patient'"'"'s body and wherein said commandable readout control means comprises an internal receiver means and an external transmitter means for communicating an externally selected readout command signal to the implanted receiver means, and further including an external receiver means and an implanted transmitter means rendered effective following communication of said readout command for transmitting said serial data output bit stream to said external receiver means.

21. The recorder system specified in claim 17 further including means rendered effective upon the occurrence of said preselected physiological event for providing a distinctive warning signal to the patient indicative of said event occurrence.

22. The recorder system as specified in claim 17 further including timing means and means for resetting said timing means, said timing means being responsive to the occurrence of said preselected physiological event for providing a registration of selected time interval information of interest in analyzing the patient'"'"'s physiological functioning represented by said physiological signal.

23. The recorder system specified in claim 22 wherein said timing means comprises a source means for generating time clocking pulses and said resetting means comprises resettable pulse counter means connected to said source means, said timing means being responsive to said physiological signal for registering a running count of the number of time clocking pulses to demarcate said selected time interval information.

24. A recorder system specified in claim 23 wherein said time interval information includes the time interval between the patient'"'"'s last readout and said event occurrence.

25. The recorder system specified in claim 24 further including event counter means responsive to said physiological signal for registering a count of the number of said physiological events occurring between readouts.

26. The recorder system specified in claim 25 wherein said signal sampling and converting means, said memory means, said pulse counter means and said event counter means are implanted in the patient'"'"'s body and further including:

implanted multiplexing means for arranging the data stored in said memory means and the count registrations of said pulse and event counter means into a serial bit stream format,

external display apparatus, and

implanted transmitter means operably connected to said multiplexing means for transmitting said serial bit stream to said external apparatus for display.

27. The recorder system specified in claim 26 wherein said implanted mulitplexing means comprises:

an output data line connected at one end to said implanted transmitter means,

a plurality of multiplexer units, one of which is connected to receive as input the contents of an associated one of said data memory means and said pulse and even counter means,

the other end of said output data line being connected in parallel to the output of each of said plurality of multiplexer units, and

timing means for sequentially rendering effective said plurality of multiplexer units to apply the contents of the associated data memory means or pulse and event counter means to said other end of the output data line.

28. The recorder system specified in claim 26 further including

means for inserting said patient-identifying code into said serial bit stream.

31. The implanted patient warning system specified in claim 26 wherein said warning signal generating means generate first and second patient stimulus signals comprising electrical pulses grouped in first and second distinctive time patterns, and wherein said converting means comprises subcutaneous energizable electrode means connected to be energized by said electrical pulses to produce patient tickling sensations enabling said patient to distinguish between (a) the detection of said abnormal cardiac activity and (b) the completion of said corrective attempt by said implanted automatic defibrillation system.

29. A recorder system for use with an automatic defibrillation system implanted in a patient and operable, in response to the detection of abnormal cardiac activity, to apply automatically defibrillation electrical impulse to the patient'"'"'s heart in an attempt to correct said abnormal activity if such activity continues for longer than a predetermined time interval, said recorder system being responsive to the patient'"'"'s electrocardiagram (ECG) signal and comprising, in combination:

means for registering the detection of said abnormal cardiac activity,

means for registering completion of a corrective attempt by said implanted automatic defibrillation system,

storage means for storing said ECG signal for a time period of interest extending substantially from the time at which said abnormal cardiac activity is detected to a predetermined time following application of said defibrillation electrical impulse by said implanted automatic defibrillation system;

means for reading out the ECG signal stored by said storage means, and

patient warning means for providing the patient with distinctive warnings of the occurrence of said abnormal cardiac activity and the responsive operation of said implanted automatic defibrillator system, said patient warning means including

warning signal generating means implanted in the patent responsive to the detection of said abnormal cardiac activity and the responsive application of said electrical impulse by said implanted automatic defibrillation system for generating first and second patient stimulus signals respectively; and

means responsive to said first and second patient stimulus signals for converting said first and second patient stimulus signals each to a different distinctive from detectable by the patient to warn the patient of said abnormal cardiac activity and said responsive defibrillation respectively.

30. The implanted patient warning system specified in claim 29 wherein said means for generating said first and second patient stimulus signals comprises a source of electrical pulses and wherein said converting means comprises subcutaneous electrode means connected to be energized by said electrical pulse and producing a patient tickling sensation.

32. A recorder system responsive to a selected physiological signal of a patient for recording said physiological signal comprising, in combination,

means for periodically converting samples of said physiological signal into a succession of digital data code words,

means for registering the occurrence of a preselected event in said physiological signal,

memory means including a plurality of random access memory (RAM) stages capable of storing said digital data code words at selected addresses within said memory means,

memory address control means responsive to said registering means for selectively addressing the RAM stages of said memory to

(a) store digital data code words corresponding to a first predetermined time interval of said physiological signal immediately preceeding said preselected event in a first portion of said memory comprising memory addresses corresponding to said first predetermined time interval, and

(b) store digital data code words corresponding to a second predetermined time interval of said physiological signal following said preselected event in a second portion of said memory comprising selected other memory addresses,

said memory address control means including means for generating address selecting signals to sequentially address all memory addresses and logic circuit means connected to said generating means for

(a) forcing said generating means to generate address selecting signals which repeatedly address in sequence said selected memory addresses corresponding to said first memory portion until said preselected event occurs in said physiological signal, and

(b) thereafter enable generation of address selecting signals which address in sequence the other memory addresses corresponding to said second memory portion, and

means for reading out the digital data code words from said memory means.

33. The recorder system specified in claim 32 further including marker means responsive to said registering means for generating a marker code signal to demarcate the address in said first memory portion corresponding to the occurrence of said preselected event.

34. The recorder system specified in claim 32 wherein said readout means includes a data output line and further including means for registering selected housekeeping data and means responsive to said memory address control means for multiplexing said housekeeping data with said data code words onto said data output line during readout.