Method and apparatus for distinguishing pacing pulses in an EKG using conduction velocity calculations

• US 5,913,828 A
• Filed: 10/29/1996
• Issued: 06/22/1999
• Est. Priority Date: 10/29/1996
• Status: Expired due to Fees

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Russell, James K.
• Primary Examiner(s): Kamm, William E.
• Assistant Examiner(s): LAYNO, CARL HERNANDZ
• Application Number:
  US08/739,336
• Time in Patent Office: 966 Days
• Field of Search: 128/696, 128/697, 600/508, 600/509, 600/510
• US Class Current: 600/509
• CPC Class Codes: A61B 5/349 Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61B 5/72 Signal processing specially adapted for physiological signals or for diagnostic purposes character recognition, recognising digital ink, document-oriented image-based pattern recognition G06V30/00; recognition or understanding of postal images G06V30/424
• CPC Class Codes: A61N 1/3702 Physiological parameters A61N1/365 takes precedence; evoked response A61N1/371

Abstract

A method and device for distinguishing man-made electrical signals within a body from physiological electrochemical activity. The method and device work by detecting electrical signals within the body, and distinguishing the man-made electrical signals from the physiological electrochemical activity by calculating conduction velocities for the detected electrical signals. In distinguishing the signals, at least one pair of points where the electrical signals are being detected is designated as being of interest. At each point within this pair, the occurrence of the arrival times of each electrical signal is observed. On the basis of these observed arrival times, the signal is then determined to be either man-made or electrophysiological in origin.

Claims

1. A method for distinguishing non-physiological electrical signals within a body from physiological electrochemical activity, said method comprising the steps of:

connecting a plurality of electrodes to the external surface of the body such that electrical signals within said body can be detected;

detecting, at a plurality of points, electrical signals within the body; and

distinguishing non-physiological electrical signals from physiological electrochemical activity by calculating conduction velocities of said detected electrical signals between selected pairs of said plurality of points.

2. The method of claim 1, wherein said step of distinguishing further comprises the steps of:

designating at least one of said selected pairs of points;

determining arrival times of one of said electrical signals at each individual point of said at least one designated pair of points;

comparing said arrival times of said one of said electrical signals at each of said individual points; and

in response to said comparison, determining whether said one of said electrical signals is either man-made or the result of said physiological electrochemical activity.

3. The method of claim 1, said body including a heart having both an apex and a base, wherein said step of connecting a plurality of electrodes to said external surface of the body further comprises the step of connecting said plurality of electrodes such that an electrocardiographic signal can be obtained and such that at least one of said plurality of electrodes is proximate to the apex of the heart and such that at least one of said plurality of electrodes is proximate to the base of the heart.

4. The method of claim 1, wherein said step of distinguishing man-made electrical signals from physiological electrochemical activity by calculating conduction velocities of said detected electrical signals between selected pairs of said plurality of points wherein said selected pairs can be selected by the method comprised of the following steps:

connecting a plurality of electrodes to said external surface of said body such that redundant pairs are formed and such that for each of said redundant pairs a first electrode of said redundant pair is proximate to the apex of the heart and a second electrode of said redundant pair is proximate to the base of the heart;

selecting, on the basis of signal quality, a first subset of electrodes from a set formed by said first electrodes of said redundant pairs;

selecting, on the basis of signal quality, a second subset of electrodes from a set formed by said second electrodes of said redundant pairs; and

creating said selected pairs of said plurality of points such that the first electrode in said designated pair is a member of said first subset and that the second electrode in said designated pair is a member of said second subset.

5. The method of claim 2 wherein said steps of determining and comparing the arrival times of said one of said electrical signals at each of said single points further comprises the step of:

establishing, for each of said at least one designated pair of points, a window of time during which said one of said electrical signals at each individual point of said at least one designated pair of points will be observed;

determining, during said window of time, the time at which the minimum and maximum of said one of said electrical signals occurs at each said individual point of said at least one designated pair of points;

calculating the difference between said time of occurrence of the minimum of said one of said electrical signals at each individual point of said at least one designated pair of points; and

calculating the difference between said time of occurrence of each maximum of said one of said electrical signals at each individual point of said at least one designated pair of points.

6. The method of claim 5, wherein said step of determining whether said one of said electrical signals is either man-made or the result of said physiological electrochemical activity further comprises the steps of:

counting, for each of said at least one designated pair of points, the number of said calculated differences which said comparison indicated is smaller than a predetermined time difference threshold; and

comparing said counted number of said time differences with a predetermined number, and designating said one of said electrical signals observed during said window of time as man-made if said counted number of time differences is greater than said predetermined number.

7. A device for distinguishing non-physiological electrical signals within a patient'"'"'s body, from physiological electrochemical activity, said device comprising:

means for detecting, at a plurality of points, electrical signals within the body; and

means for distinguishing non-physiological electrical signals from physiological electrochemical activity by calculating conduction velocities of said detected electrical signals between selected pairs of said plurality of points.

8. The device of claim 7, wherein said means of distinguishing further comprises:

means for designating at least one of said selected pairs of points;

means for determining arrival times of one of said electrical signals at each individual point of said at least one designated pair of points;

means for comparing said arrival times of said one of said electrical signals at each of said single points; and

means for, in response to said comparison, determining whether said one of said electrical signals is either man-made or the result of said physiological electrochemical activity.

9. The device of claim 7, wherein said means for detecting comprises a means for connecting a plurality of electrodes to the external surface of the body such that electrical signals within said body can be detected.

10. The device of claim 9, said body including a heart having both an apex and a base, wherein said means for connecting a plurality of electrodes to the external surface of the body comprises the connecting of said plurality of electrodes such that an electrocardiographic signal can be obtained and such that at least one of said plurality of electrodes is proximate to the apex of the heart and such that at least one of said plurality of electrodes is proximate to the base of the heart.

11. The device of claim 7, wherein said means for distinguishing man-made electrical signals from physiological electrochemical activity by calculating conduction velocities of said detected electrical signals between selected pairs of said plurality of points wherein said selected pairs can be selected by a device comprising:

means for connecting a plurality of electrodes to said external surface of said body such that redundant pairs are formed and such that for each of said redundant pairs a first electrode of said redundant pair is proximate to the apex of the heart and a second electrode of said redundant pair is proximate to the base of the heart;

means for selecting, on the basis of signal quality, a first subset of electrodes from a set formed by said first electrodes of said redundant pairs;

means for selecting, on the basis of signal quality, a second subset of electrodes from a set formed by said second electrodes of said redundant pairs; and

means for creating said selected pairs of said plurality of points such that the first electrode in said designated pair is a member of said first subset and that the second electrode in said designated pair is a member of said second subset.

12. The device of claim 8, wherein said means determining and comparing the arrival times of said one of said electrical signals at each of said single points is a device further comprising:

means for establishing, for each of said at least one designated pair of points, a window of time during which said one of said electrical signals at each individual point of said at least one designated pair of points will be observed;

means for determining, during said window of time, the time at which the minimum and maximum of said one of said electrical signals occurs at each said individual point of said at least one designated pair of points;

means for calculating the difference between said time of occurrence of the minimum of said one of said electrical signals at each individual point of said at least one designated pair of points; and

means for calculating the difference between said time of occurrence of each maximum of said one of said electrical signals at each individual point of said at least one designated pair of points.

13. The device of claim 12, wherein said means for determining whether said one of said electrical signals is either man-made or the result of said physiological electrochemical activity further comprises the steps of:

means for counting, for each of said at least one designated pair of points, the number of said calculated differences which said comparison indicated are smaller than a predetermined time difference threshold; and

means for comparing said counted number of said time differences with a predetermined number, and designating said one of said electrical signals observed during said window of time as man-made if said counted number of time differences is greater than said predetermined number.