Fiducial point location

• US 4,170,992 A
• Filed: 01/05/1978
• Issued: 10/16/1979
• Est. Priority Date: 01/05/1978
• Status: Expired due to Term

• Current Assignee: Hewlett-Packard Company (HP Inc.)
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Dillman, Richard F.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US05/867,265
• Time in Patent Office: 649 Days
• Field of Search: 128/206 A, 128/206 R, 364/417
• US Class Current: 600/515
• CPC Class Codes: A61B 5/352 Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval

Abstract

Ventricular ectopic heartbeats are detected by comparing the ECG wave for a current heartbeat with the ECG wave of a heartbeat considered to be normal for that patient. The waves are aligned with their fiducial points in time coincidence, and the fiducial points are located at the centroids of the ECG waves.

Claims

1. In a patient monitoring system having an input to which signals derived from an ECG machine that represent the heartbeat cycle of a patient may be applied, the combination of

means coupled to said input for giving information as to the location of a fiducial point in the signal representing each heartbeat cycle, said fiducial point being located at the centroid,

memory means for storing one of said signals and information as to the location of its fiducial point,

means for matching unknown signals representing heartbeat cycles with the one said heartbeat cycle that has been stored in such manner that their respective fiducial points are in time coincidence so as to provide at its output information as to the degree of correlation between each received signal and the said signal stored in said memory means, and

means coupled to the output of said matching means for producing one indication when the unknown signal is ectopic and another indication when it is not ectopic.

2. The combination of

an input to which ECG waves representing the heartbeat cycle of a patient may be applied,

a QRS detector coupled to said input for giving information at its output as to the occurrence of a preliminary fiducial point of the ECG wave for each heartbeat cycle,

fiducial point location means coupled to said input and to the output of said QRS detector for providing information as to the time of occurrence within each heartbeat cycle of a corrected fiducial point with respect to the time of occurrence of the preliminary fiducial point in accordance with the expression ##EQU8## memory means coupled to said input and to said fiducial point location means for storing an ECG waveform and information as to the time within that waveform at which its corrected fiducial point occurs,

matching means coupled to said input and to said memory means for producing at its output signals indicative of the difference in form of the ECG waveform at said input with the waveform stored in said memory means in such manner that their corrected fiducial points are effectively in time coincidence, and

means responsive to the signals including those produced by said matching means for indicating whether the ECG waveform derived from said input is ectopic.

3. The combination of

an input to which ECG signals representing heartbeat cycles of a patient may be applied,

fiducial point determining means coupled to said input for giving information as to the time of occurrence of the centroid of each heartbeat cycle,

storage means coupled to the output of said fiducial point determining means for retaining information as to the time of occurrence of the centroid of the ECG wave representing one heartbeat cycle at least until information as to the time of occurrence of the centroid of the ECG wave representing the next heartbeat cycle is available, and

means coupled to said storage means and said fiducial point determining means for providing a signal corresponding to the difference in time between the occurrence of the centroid of the ECG wave representing the said one heartbeat cycle and the time at which the centroid for a successive heartbeat cycle occurs.

4. The combination of

an input to which ECG waves representing the heartbeat cycle of a patient may be applied,

a QRS detector coupled to said input for giving information at its output as to the occurrence of a preliminary fiducial point of the ECG wave for each heartbeat cycle,

fiducial point location means coupled to said input and to the output of said QRS detector for providing information as to the time of occurrence within each heartbeat cycle of a corrected fiducial point with respect to the time of occurrence of the preliminary fiducial point in accordance with the expression ##EQU9## storage means coupled to the output of said fiducial point determining means for retaining information as to the time of occurrence of the centroid of the ECG wave representing one heartbeat cycle at least until information as to the time of occurrence of the centroid of the ECG wave representing the next heartbeat cycle is available, and

means coupled to said storage means and said fiducial point determining means for providing a signal corresponding to the difference in time between the occurrence of the centroid of the ECG wave representing the said one heartbeat cycle and the time at which the centroid for a successive heartbeat cycle occurs.

5. Apparatus for determining the difference in time between the time of a fiducial point of an ECG wave and a reference time comprising in combination,

an input to which a signal representing an ECG wave may be applied,

means for providing an indication representing a reference time,

means for deriving a first signal representing the variation of one of a group of derivatives including the zero order derivative, with respect to time of an ECG wave applied to said input,

means for providing a second signal representing the first signal raised to a power,

means for providing a third signal representing the time elapsed from the reference time,

means for deriving a fourth signal representing the product of the values represented by said second and third signals respectively,

means for producing a fifth signal representing the effective integration of the values represented by said fourth signal between times which define a period including at least a portion of the ECG waveform,

means for producing a sixth signal representing the effective integration of the values represented by said second signal over said period, and

means for deriving a seventh signal representing the division of the value represented by said fifth signal by the value represented by said sixth signal, the seventh signal representing the difference in time between the reference time and the fiducial point for the ECG wave.