Implantable cardiac stimulator with automatic gain control and bandpass filtering in feedback loop
First Claim
1. Apparatus for detecting cardiac arrhythmias by analyzing ECG signals produced by the heart, comprising:
- filter means forming dual signal paths having different bandpass characteristics for receiving said ECG signals, one of said signal paths constituting means for determining a sensing level for the ECG signals, and the other of the signal paths constituting feedback loop means for determining ECG signal gain and a sensing margin which is a function of the frequency content of the ECG signal.
1 Assignment
0 Petitions
Accused Products
Abstract
An implantable cardiac stimulator for detecting and treating cardiac arrhythmias includes a sense amplifier responsive to sensed cardiac signals for detecting and distinguishing normal and abnormal cardiac activity within the sensed signals. The sense amplifier includes an automatic gain control amplifier, a filter and quad comparator having a pair of signal channels for processing the sensed signals according to different frequency bandpass characteristics to establish sensing thresholds, margins and signal gain. The sense amplifier has a feedback loop containing a microprocessor which implements preselected algorithms in conjunction with the outputs of the quad comparator to variably adjust the amplifier gain and to programmably control the sensing margin.
191 Citations
34 Claims
-
1. Apparatus for detecting cardiac arrhythmias by analyzing ECG signals produced by the heart, comprising:
filter means forming dual signal paths having different bandpass characteristics for receiving said ECG signals, one of said signal paths constituting means for determining a sensing level for the ECG signals, and the other of the signal paths constituting feedback loop means for determining ECG signal gain and a sensing margin which is a function of the frequency content of the ECG signal. - View Dependent Claims (2, 3, 4, 5, 6)
-
7. Implantable apparatus for detecting cardiac arrhythmias, comprising:
-
electrode means for sensing electrical activity of a patient'"'"'s heart, and processing means responsive to the sensed electrical activity for determining whether sensed events are indicative of arrhythmias, said processing means including target means establishing at least one reference level against which the amplitudes of predetermined sensed events are compared, gain control means controllably varying sensitivity of the processing means according to the amplitude of each sensed event relative to said at least one reference level, and comparison means responsive to said gain control means being adjusted in sensitivity in one direction immediately following an adjustment in the other direction for counting the number of times the sensed event crosses the reference level as an indication of the nature of the arrhythmia. - View Dependent Claims (8)
-
-
9. An implantable stimulator for detecting and treating cardiac arrhythmias, comprising:
-
sensing means responsive to electrical activity of a heart and adapted to produce electrical signals representative of electrical activity of the heart, and signal processing means forming dual signal paths with different bandpass characteristics and responsive to the electrical signals for programmably controlling the sensing margin of the stimulator to components of said signals indicative of arrhythmia. - View Dependent Claims (10, 11, 12)
-
-
13. Method of detecting cardiac arrhythmias, comprising the steps of:
-
providing means for detecting electrical activity of a heart including both sinus rhythm and arrhythmias and producing electrical signals representative of that activity; and processing the electrical signals along dual signal paths having different bandpass characteristics while variably controlling sensitivity in response to selected components of said signals whereby detection of arrhythmias of interest is enhanced. - View Dependent Claims (18, 19)
-
-
14. An implantable defibrillator for automatically treating cardiac abnormalities, comprising:
-
means for detecting electrical activity representing cardiac abnormalities of a heart; and means defining dual signal paths having different bandpass characteristics and responsive to the detected electrical activity for enhancing the frequency characteristics thereof and the amplitude of preselected frequency content indicative of designated cardiac abnormalities relative to predetermined threshold levels, to distinguish various abnormalities from one another including fibrillation, bradycardia, and tachycardia, to treat said abnormality.
-
-
15. An implantable cardiac stimulator for detecting cardiac arrhythmias, comprising:
-
means for sensing cardiac signals; amplifier means responsive to sensed cardiac signals for detecting and distinguishing normal and abnormal cardiac activity therefrom, said amplifier means including; means defining dual signal paths for processing portions of the sensed signals representative of cardiac activity in two frequency bands each having different bandpass characteristics, and means in one of said signal paths for automatically adjusting the gain of the amplifier means according to the amplitude of the signals in one said frequency band to detect abnormal cardiac activity therefrom. - View Dependent Claims (16, 17, 20, 21, 22, 23)
-
-
24. An implantable cardiac stimulator for detecting cardiac arrhythmias by analyzing electrical signals produced by the heart, comprising:
-
means for detecting electrical signals produced by the heart; and amplifier means responsive to the detected signals and having dual signal paths for said detected signals, each said signal path having different bandpass characteristics, means defining a feedback loop in one of said paths for automatically adjusting the gain of the amplifier means whereby gain and threshold relationships between said dual signal paths are controlled to produce variable sensing margins for different input waveforms. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31)
-
-
32. An implantable defibrillator for automatically treating cardiac abnormalities, comprising:
-
means for detecting electrical signals of a heart and distinguishing electrical signals representing cardiac abnormalities; and dual signal path means receiving said detected signals, each said path means having a different bandpass characteristic one said signal path means determining a sensing level for said signals and the other signal path having feedback loop means controlling gain thereby producing different sensing margins for different input electrical signal waveforms. - View Dependent Claims (33, 34)
-
Specification