US 5,117,824 A · Apparatus for monitoring electrical physiologic signals

Abstract

An implantable cardiac pacemaker and/or cardioverter/defibrillator employing an R-wave detector which atuomatically adjusts its sensing threshold in response to R-wave amplitude. The R-wave detector produces an output which is used to indicate the occurrence of ventricular contractions, and is used to reset the timing of the pacemaker and to indicate the occurrence of ventricular contractions for purposes of activating the associated cardioverter/defibrillator. Adjustment of the threshold is disable for a predetermined period following the delivery of each pacing pulse such that in the presence of continuous pacing for a predetermined period of time, the sensing threshold is returned to a desired, lower threshold level, allowing for detection of lower level R-waves, which may be indicative of tachyarrhythmia or fibrillation. The R-wave detector disclosed also eliminates the necessity for blanking of the input of the sense amplifier following sensing of naturally occurring R-waves, without increasing susceptibility to sensing of spontaneous T-waves which occur thereafter.

Claims13

Dependent claims

In an implantable cardioverter comprising means for detecting a tachyarrhythmia and means for treating said tachyarrhythmia, said cardioverter also comprising pulse generator means for generating cardiac pacing pulses, the improvement comprising:

variable threshold R-wave detector means for detecting the occurrence of R-waves and for providing output signals indicative of the detection of said R-waves, said signals provided to said tachyarrhythmia detection means, said variable threshold R-wave detector means comprising means for defining an R-wave detection threshold and means for adjusting said R-wave detection threshold to a value based upon the amplitude of a detected R-wave and further includes means for gradually reducing said R-wave detection threshold following said detected R-wave;
cardiac pacemaker timing means for defining a V--V interval and for triggering said pulse generator means at the expiration of said V--V interval, said timing means reset by the output of said R-wave detector means;
and
disable means for disabling said threshold adjusting means from adjusting said R-wave detection threshold in response to an R-wave following a cardiac pacing pulse from said pulse generator means.

1 more element

Dependencies are inferred from the claim text.

Apparatus for monitoring electrical physiologic signals

Life of this patent

Apparatus for monitoring electrical physiologic signals

Life of this patent

Abstract

Claims13