Circuit for monitoring a heart and for effecting cardioversion of a needy heart
First Claim
1. A circuit for detecting the state of a heart by monitoring the continuous time average of the ratio of high slope to low slope ECG segments and for effecting cardioversion if a malfunction is indicated by such time average ratio exceeding a predetermined threshold, the circuit comprising:
- ECG monitor means for sensing ECG signals from a heart;
signal shaping means for generating the slope of the sensed ECG signals by providing an approximation of the derivative of the input ECG;
means for discriminating between high slope and low slope segments;
averaging means for continuously time averaging the ratio of high slope to low slope segments;
threshold means for determining whether such time average ratio of high slope to low slope segments is within predetermined threshold limits indicative of normalcy; and
means for effecting cardioversion if said ratio is outside said threshold.
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Accused Products
Abstract
Disclosed are two embodiments of a circuit for analyzing the ECG signals of a heart and for delivering a cardioverting pulse of energy to the heart if the heart is in an arrhythmic state in need of cardioversion. In the first embodiment, the ECG is filtered by a high pass filter to provide the derivative of the ECG, is reviewed by a window detector to determine the average time that the input ECG spends at high slope, and then the average occurrence of high slope segments is compared with a predetermined reference to determine whether the ECG is normal. Cardioversion is effected if the ECG is abnormal. In the second embodiment, an absolute value circuit and a level comparator is used in place of the window detector. The input ECG is normalized by an automatic gain control where the AGC voltage is derived from the ECG signals after high pass filtration.
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Citations
16 Claims
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1. A circuit for detecting the state of a heart by monitoring the continuous time average of the ratio of high slope to low slope ECG segments and for effecting cardioversion if a malfunction is indicated by such time average ratio exceeding a predetermined threshold, the circuit comprising:
- ECG monitor means for sensing ECG signals from a heart;
signal shaping means for generating the slope of the sensed ECG signals by providing an approximation of the derivative of the input ECG;
means for discriminating between high slope and low slope segments;
averaging means for continuously time averaging the ratio of high slope to low slope segments;
threshold means for determining whether such time average ratio of high slope to low slope segments is within predetermined threshold limits indicative of normalcy; and
means for effecting cardioversion if said ratio is outside said threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 13, 14, 15, 16)
- ECG monitor means for sensing ECG signals from a heart;
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9. A circuit for detecting the state of a heart by monitoring the continuous time average of the ratio of high slope to low slope ECG segments and for effecting cardioversion if a malfunction is indicated by such time average ratio exceeding a predetermined threshold, the circuit comprising:
- ECG monitor means for sensing ECG signals from a heart;
signal shaping means for generating the slope of the sensed ECG signals by providing an approximation of the derivative of the input ECG;
automatic gain control means for normalizing the height of the derivative peaks, said automatic gain control means having a pick-off point at a location after the input ECG signals are shaped;
means for discriminating between high slope and low slope segments;
averaging means for continuously time averaging the ratio of high slope to low slope segments;
threshold means for determining whether such time average ratio of high slope to low slope segments is within predetermined threshold limits indicative of normalcy; and
means for effecting cardioversion if said ratio is outside said threshold. - View Dependent Claims (10, 11, 12)
- ECG monitor means for sensing ECG signals from a heart;
Specification