Method and apparatus for accurate counting of paced heartbeats

• US 5,771,898 A
• Filed: 12/19/1996
• Issued: 06/30/1998
• Est. Priority Date: 12/19/1996
• Status: Expired due to Term

• Current Assignee: Draeger Medical Systems Incorporated (FPS Vermögensverwaltung GmbH)
• Original Assignee: Siemens Medical Systems, Inc. (Siemens AG)
• Inventors: Marinello, Stephen A.
• Primary Examiner(s): Jastrzab, Jeffrey R.
• Application Number:
  US08/770,034
• Time in Patent Office: 558 Days
• Field of Search: 128/696, 128/697, 128/702, 128/706, 128/707, 128/901
• US Class Current: 600/510
• CPC Class Codes: A61B 5/0245 by using sensing means generating electric signals, i.e. ECG signals
• CPC Class Codes: A61N 1/3702 Physiological parameters A61N1/365 takes precedence; evoked response A61N1/371
• CPC Class Codes: Y10S 128/901 Suppression of noise in electric signal

Abstract

A heartrate monitor of the invention includes a signal receiver adapted for being coupled to at least one sensor coupled to a medical patient, for providing an ECG signal and a pacemaker detection signal. A pacemaker activity checker, responsive to the pacemaker detection signal and the ECG signal provides first and second output signals, the first output signal indicating the occurrence of a QRS complex in the vicinity of the pacemaker detection signal, and the second output signal indicating the occurrence of an overshoot in the vicinity of the pacemaker detection signal. An overshoot validator, responsive to the ECG signals and the second output signal indicates the validity of the indicated overshoot. A QRS detector, responsive to the ECG signal, indicates the occurrence of a QRS complex in the ECG signal. A logic combining means, responsive to at least the first output signal, the output of the overshoot validator and the output of the QRS detector, determines a combined QRS detection signal, that accurately indicates the occurrence of QRS'"'"'s. A heartrate determining means responsive to the combined QRS detection signal provides an accurate indication of the heartrate for the medical patient.

Claims

1. A heartrate monitor including a QRS detector for detecting QRS complexes in the presence of pacemaker pulses, comprising:

a signal receiver adapted for being coupled to at least one sensor coupled to a medical patient, for providing an ECG signal and a pacemaker detection signal;

a pacemaker activity checker, responsive to said pacemaker detection signal and said ECG signal for providing first and second output signals, said first output signal indicating the occurrence of a QRS complex in the vicinity of the pacemaker detection signal, and the second output signal indicating the occurrence of an overshoot in the vicinity of the pacemaker detection signal;

an overshoot validator, responsive to said ECG signals and said second output signal for indicating the validity of the indicated overshoot;

a QRS detector, responsive to said ECG signal, for indicating the occurrence of a QRS complex in said ECG signal;

a logic combining means, responsive to at least said first output signal, the output of said overshoot validator and the output of said QRS detector, for determining a combined QRS detection signal; and

heartrate determining means responsive to said combined QRS detection signal for indicating a heartrate for the medical patient.

2. Apparatus in accordance with claim 1, wherein a differentiating filter is provided for filtering said ECG signals before they are applied to said pacer activity checker, and slope detection techniques are used to detect said QRS complexes and pacemaker pulses.

3. Apparatus in accordance with claim 1, wherein said logic combining means operates in accordance with the following table:

space="preserve" listing-type="tabular">______________________________________ Second First signal signal Action on QRS'"'"'s from QRS Detector ______________________________________ True False Inhibit QRS True False Count QRS as paced QRS if dual-chamber False False Count QRS as paced QRS if dual-chamber True True Count QRS as paced QRS False True Count QRS as non-paced QRS False False Count QRS as non-paced QRS ______________________________________

4. Apparatus in accordance with claim 1, wherein said pacemaker activity checker provides as said first output signals an indication of the occurrence of a QRS complex that follows the pacemaker detection signal, and a third output signal indicating the occurrence of a QRS complex that preceeds the pacemaker detection signal.

5. Apparatus in accordance with claim 4, wherein said logic combining means operates in accordance with the following table:

space="preserve" listing-type="tabular">______________________________________ Second Third First signal signal signal Action on QRS'"'"'s from QRS Detector ______________________________________ True False False Inhibit QRS True True False Count QRS as paced QRS if dual-chamber False True False Count QRS as paced QRS if dual-chamber True False True Count QRS as paced QRS False False True Count QRS as non-paced QRS False False False Count QRS as non-paced QRS ______________________________________

6. A method for operating a QRS detector for detecting QRS complexes in the presence of pacemaker pulses, comprising the following steps:

processing an ECG signal so as to develop a pacemaker pulse detection signal;

processing said ECG signal so as to develop first and second output signals indicating signal activity in the vicinity of detected pacemaker pulses, said first output signal indicating the occurrence of a QRS complex in the vicinity of the pacemaker detection signal, and the second output signal indicating the occurrence of an overshoot in the vicinity of the pacemaker detection signal;

validating said second output signal for indicating the validity of the indicated overshoot;

indicating the occurrence of a QRS complex in said ECG signal;

processing said first and second output signals and the indication of a QRS complex, for determining a combined QRS detection signal; and

determining a heartrate in responsive to said combined QRS detection signal.