SYSTEM AND METHOD FOR ANALYZING ABSOLUTE DERIVATIVE SIGNAL FROM HEARTBEAT

• US 3,821,948 A
• Filed: 11/03/1971
• Issued: 07/02/1974
• Est. Priority Date: 11/03/1971
• Status: Expired due to Term

• Current Assignee: Kontron (S&T AG)
• Original Assignee: Eugene King
• Inventors: King, Eugene
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US05/195,396
• Time in Patent Office: 972 Days
• Field of Search: 128/2.6A,2.6F,2.6R,2.5P,2.5R,2.5T 307/235
• US Class Current: 600/508
• CPC Class Codes: A61B 5/349 Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• CPC Class Codes: A61B 5/7242 using integration
• CPC Class Codes: Y10S 128/901 Suppression of noise in electric signal

Abstract

An arrhythmia detection system for analyzing electrocardiographic signals comprising transforming a filtered, absolute, derivative of the electrocardiographic signals into a first integral signal defining an adaptive threshold level and depending from prior heart beat signals, transforming the electrocardiographic signals into a second integral signal representative of a heart beat virtually independent from prior heart beat signals, and comparing the levels of the first and second integral signals for generating a QRS trigger pulse. Further aspects include providing a third integral signal accentuating noise and comparing its level with the first integral signal level for inhibiting QRS trigger signals during noise occurrence.

Claims

1. An arrhythmia detection system for analyzing an absolute derivative signal derived from a patient'"'"''"'"'s heartbeat comprising:

first integrator means for generating a first signal representative of the average magnitude of an incoming absolute derivative signal over a plurality of heartbeats;

second integrator means for generating a second signal representative of the magnitude of an incoming absolute derivative signal over a single heartbeat; and

comparison means for comparing the magnitude of said first and second signals and generating an output representative of cardiac activity when the second signal magnitude attains a predetermined relationship with respect to the first signal magnitude.

2. The system of claim 1 including narrow filter means for filtering the absolute derivative signal.

3. The system of claim 2 wherein said narrow filter means is adapted to pass an absolute derivative signal in the range from approximately 10 to 15 cycles.

4. The system of claim 1 including:

third integrator means for selectively providing a third signal accentuating noise associated with said absolute derivative signal; and

, second comparison means for comparing the signal magnitude of said first and third signals and generating an output signal indicative of noise when the third signal magnitude attains a predetermined relationship with respect to the first signal magnitude.

5. The system of claim 4 including:

inhibiting means for inhibiting the output signal of the first comparison means indicative of cardiac activity, at least during the presence of said noise output signal.

6. The system of claim 4 including:

discharge means responsive to said noise output signal for rapidly attenuating the first signal at said first integrator means.

7. The system of claim 1 wherein:

said first integrator means is provided with a relatively long attack and release times so as to depend from the signal level of a prior heartbeat signal enabling said first signal to immediately adapt to a patient'"'"''"'"'s changing morphology; and

said second integrator means is provided with a relatively fast attack and release times so as not to be influenced by and thereby be virtually independent of the signal level of a prior heartbeat signal.

8. The system of claim 1 wherein said second processing means is providing a decay rate to virtually attenuate to ground said second integral signal within 350 milliseconds or less.

9. The system of claim 8 wherein said first integrator means is provided a decay rate to virtually attenuate to ground the first integral signal within approximately anywhere from 3-4 seconds.

10. A metHod of analyzing an absolute derivative signal derived from a patient'"'"''"'"'s heartbeat comprising the steps of:

transforming the absolute derivative signal into a first integral signal representative of the average magnitude of an absolute derivative signal over a plurality of heartbeats;

transforming the absolute derivative signal into a second integral signal representative of the magnitude of an absolute derivative signal over a single heartbeat;

comparing the signal magnitude of said first and second integral signals to generate an output cardiac signal when the second integral signal magnitude attains a predetermined relationship with respect to the first integral signal magnitude.