US 5,010,887 A · Noise discrimination in implantable pacemakers

Abstract

A noise discrimination circuit determines if sensed electrocardiographic (ECG) pulsed signals sensed within a pulse generator are valid ECG signals, i.e., valid P-waves or R-waves, or noise. The ECG signal may then be processed. The processed ECG signal is monitored to determine both the amplitude and duration of any signal pulses appearing thereon. If the amplitude of a given ECG signal pulse exceeds a prescribed threshold level for a prescribed time period, the pulse is considered to be a valid ECG signal. The noise discrimination circuit includes: a threshold detector for determining if the amplitude of the ECG signal exceeds the prescribed threshold level; a timer circuit for generating a timed window signal, triggered by the threshold detector whenever the ECG signal amplitude exceeds the prescribed threshold level; and logic circuitry for determining if the amplitude of the ECG signal remains above the threshold level for the duration of the timed window signal. One embodiment allows the prescribed threshold level and duration of the timed window signal to be programmably selected.

Claims21

Dependent claims

A noise discrimination circuit used in an implantable medical device, said implantable medical device including sensing means for sensing electrical signals originating within heart tissue with which said medical device is in electrical contact, said sensing means comprising a single wire lead in contact with said heart tissue, said noise discrimination circuit comprising:

first and second threshold detectors coupled to the sensing means, the first threshold detector generating a first signal when the electrical signal sensed exceeds a first threshold value, the second threshold detector generating a second signal when the electrical signal sensed falls below a second threshold value;
timer means for generating a window signal having a prescribed time period, the window signal being triggered whenever the electrical signal sensed exceeds the first threshold value;
latch means for generating a latch signal upon the occurrence of the first signal and for terminating the latch signal upon the occurrence of the second signal;
and
means for designating the electrical signal sensed as being valid during an interval defined by the absence of the window signal and the presence of the latch signal.

2 more elements

Dependencies are inferred from the claim text.

Noise discrimination in implantable pacemakers

Life of this patent

Noise discrimination in implantable pacemakers

Life of this patent

Abstract

Claims21