"PACEMAKER" MONITORING TECHNIQUE AND SYSTEM

• US 3,782,367 A
• Filed: 02/25/1972
• Issued: 01/01/1974
• Est. Priority Date: 02/25/1972
• Status: Expired due to Term

• Current Assignee: Kontron (S&T AG)
• Original Assignee: Eugene King, Howard Martin Hochberg
• Inventors: King, Eugene, Hochberg, Howard Martin
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US05/229,495
• Time in Patent Office: 676 Days
• Field of Search: 128/2.5R,2.6A,2.6R,419P,421,422
• US Class Current: 600/510
• CPC Class Codes: A61B 5/24 Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
• CPC Class Codes: A61B 5/7217 of noise originating from a therapeutic or surgical apparatus, e.g. from a pacemaker
• CPC Class Codes: A61N 1/368 comprising more than one electrode co-operating with different heart regions A61N1/3622, A61N1/3627 take precedence
• CPC Class Codes: A61N 1/371 Capture, i.e. successful stimulation
• CPC Class Codes: A61N 1/3714 Atrial capture

Abstract

A monitoring system operates to indicate the effectiveness of cardiac pacer operation in a cardiac pacer carrying patient. A predetermined time interval from the onset of a pacer spike defines minimum and maximum specific times as criteria for establishing digital techniques to ascertain a capture event or whether the patient'"'"''"'"'s QRS is driven by the pacer spike. Additional digital circuitry indicates when a non-capture event has occurred as the cardiac pacer output has failed. By selective switching which includes proper routing of the atrial and ventricular spikes, the system is adapted to monitor atrial, ventricular and atrial-ventricular sequential pacing, whether in the fixed or demand modes. With atrial-ventricular sequential pacing the predetermined interval from onset of the atrial spike defines minimum and maximum times to ascertain if atrialventricular capture has occurred.

Claims

1. A monitoring system for indicating the effectiveness of cardiac pacer operation in a cardiac pacer carrying patient with relation to the patient derived QRS comprising:

means for deriving EKG and pacer spike data from a patient and generating a QRS pulse from said EKG data;

circuit means including means for establishment of a predetermined time interval from the onset of a pacer spike, for producing an output pulse upon occurrence of the QRS pulse within said predetermined time interval; and

indicator means responsive to said output pulse for denoting occurrence of a capture event.

2. A system according to claim 1 wherein said circuit means further includes means for signaling absence of the QRS from within the predetermined time interval;

and second indicator means responsive to said signaling absence means for denoting occurrence of a non-capture event.

3. A system according to claim 2 including:

alarm detection means adapted to respond to said non-capture events and generate an alarm signal upon detection of at least two of said non-capture events within a specified time period; and

alarm indicator means responsive to said alarm signal.

4. A system according to claim 3 wherein said alarm detection means includes counter means adapted to energize said alarm indicator in response to a count of a preselected number of non-capture events.

5. A system according to claim 2 whereby said circuit means further includes:

delay means for producing in response to said pacer spike a delayed pulse at the end of said predetermined time interval; and

said signaling means including gating means adapted to be enabled by said delayed pulse in the absense of a capture event.

6. A system according to claim 1 including:

QRS indicator means responsive to said QRS pulse; and

gate means connected from said circuit means for inhibiting response of said QRS indicator means to said QRS pulse in the presence of a capture event.

7. A system according to claim 1 wherein said circuit means further includes:

first circuit means having a first predetermined time interval from the onset of a ventricular pacer spike, for producing a first output pulse upon occurrence of the QRS within said first predetermined time interval representing occurrence of a ventricular-capture event;

second circuit means having a second predetermined time interval from the onset of an atrial pacer spike for producing a second output pulse upon occurrence of a ventricular pacer spike within said second predetermined time interval representing occurrence of an atrial-ventricular capture event; and

third circuit means having a third predetermined time interval from the onset of an atrial pacer spike, for producing a third output pulse upon occurrence of the QRS within said third predetermined time interval representing occurrence of an atrial-capture event.

8. A system according to claim 7 including:

switch means for routing in a cardiac cycle, a first derived pacer spike to said second and third circuit means and a second derived pacer spike to said first and second circuit means.

9. A system according to claim 1 wherein said circuit means includes:

first pulse forming means responsive to the pacer spike for generating a first pulse to continue to the end of said predetermined time interval;

second pulse forming means responsive to said QRS, for generating a second pulse defining a capture window approximately equal to the width of the predetermined time interval; and

gating means responsive to simultaneous occurrence of said first and second pulses to denote a capture event.

10. A system according to claim 1 wherein said ciRcuit means includes:

first pulse forming means responsive to a first pacer spike in a cardiac cycle, for generating a first pulse to continue to the end of said predetermined time interval;

second pulse forming means responsive to a successive pacer spike in the cardiac cycle, for generating a third pulse defining a capture window approximately equal to the width of the predetermined time interval; and

gating means responsive to simultaneous occurrence of said first and second pulses to denote a capture event.

11. A system according to claim 1 adapted for monitoring a cardiac pacer of the ventricular type wherein said predetermined time interval extends in approximate range of, at least 0 to 300 ms from onset of the ventricular cardiac pacer spike.

12. A system according to claim 1 adapted for monitoring a cardiac pacer of the atrial-ventricular type wherein said predetermined time interval extends an approximate range of, at least 120 to 250 ms from onset of the atrial cardiac pacer spike.

13. A system according to claim 1 adapted for monitoring a cardiac pacer of the atrial type wherein said predetermined time interval extends an approximate range of 120 to 275 ms from onset of the atrial spike.

14. A system according to claim 1 wherein a cardiac pacer of the fixed type is to be maintained including:

second indicator means for denoting the absence of a non-capture event; and

gating means responsive to a QRS pulse in the absence of a capture event for energizing said second indicator means.

15. A method of automatically evaluating the effectiveness of a cardiac pacer in a cardiac pacer carrying patient comprising:

deriving from a patient EKG data and pacer spike data and generating a QRS trigger from the EKG data during successive cardiac cycles;

developing a time range from the onset of the pacer spike for defining pacer driving of the QRS;

relating in a cardiac cycle, the occurrence of the QRS with respect to the pacer spike to ascertain if the former falls within said time range; and

indicating a capture event when the pacer is found to drive the QRS.

16. A method according to claim 15 including:

signaling the absence of the QRS within said time range to denote a non-capture event.

17. A method according to claim 16 including:

counting a number of non-capture events within a predetermined continuously updated time interval; and

indicating an alarm condition upon counting a preselected number of such non-capture events within one of said time intervals.

18. A method according to claim 15 including:

indicating occurrence of each QRS; and

inhibiting the QRS indicating step during the occurrence of a capture event.

19. A system for the automatic evaluation of the effectiveness of a cardiac pacer in a cardiac pacer carrying patient comprising:

means for deriving EKG data and pacer spike data;

means for detecting a QRS trigger signal from said EKG data;

circuit means for establishing a minimum and maximum time range from onset of the pacer spike including first means responsive to the pacer spike for producing a delayed pulse of relatively short duration at said maximum time range and a second means responsive to said QRS trigger signal for producing a window pulse having an interval of approximately the difference between the minimum and maximum time range;

first gating means adapted to produce an output pulse in response to simultaneous occurrence of said first and second pulses; and

indicator means responsive to said output pulse for denoting occurrence of a capture event.

20. A system according to claim 19 including:

second indicator means for denoting occurrence of a non-capture event;

pulse forming means responsive to said pacer spike for producing a second delayed pulse; and

second gating means responsive to said second delayed pulse and the absence of an output pulse at said first gating means, for energizing said second indicator means.

21. A system according to claim 20 including:

alarm logic detection means including counting means adapted to respond to said non-capture events and generate an alarm signal upon detection of at least two of said non-capture events within a specified time period; and

alarm indicator means responsive to said alarm signal.

22. A system according to claim 19 wherein said circuit means further includes:

first circuit means with a first set of time ranges and having a first window pulse, for producing a first output pulse upon occurrence of the delayed pulse within said window pulse interval representing occurrence of a ventricular-capture event;

second circuit means with a second set of time ranges and having a second window pulse, for producing a second output pulse upon occurrence of a ventricular pacing spike within said second window interval representing occurrence of an atrial-ventricular capture event; and

third circuit means with a third set of time ranges and having a third window pulse, for producing a third output pulse upon occurrence of said delayed pulse within said third window interval representing occurrence of an atrial-capture event.

23. A system according to claim 22 including:

switch means for routing, in a cardiac cycle, a first derived pacer spike to said second and third circuit means and a second derived pacer spike to said first and second circuit means.