Method and apparatus for adjusting the sensing threshold of a cardiac rhythm management device
AssigneeCardiac Pacemakers, Inc.
InventorsGeng Zhang, Oingsheng Zhu, Laura Mepham, Jesse W. Hartley
Life of this patent
Estimating the term…
Abstract
A method and apparatus for automatically adjusting the sensing threshold of cardiac rhythm management devices. The invention is particularly suited for implementation in devices such as implantable cardiac pacemakers and implantable cardioverter/defibrillators. A method and apparatus are provided in which a noise level and signal level for a sensing channel are determined for each cardiac cycle with the sensing threshold of the channel being adjusted in accordance therewith.
Claims20
A method for automatically adjusting a sensing threshold in a cardiac rhythm management device, comprising:
- sensing a ventricular electrogram signal with a ventricular sensing channel and detecting a ventricular depolarization event when the sensed ventricular signal exceeds a ventricular sensing threshold;
- sensing an atrial electrogram signal with an atrial sensing channel and detecting an atrial depolarization event when the sensed atrial signal exceeds an atrial sensing threshold;
- adjusting the sensing threshold for a sensing channel for a current cardiac cycle during a refractory period beginning with either detection of an r-wave or delivery of a ventricular pacing pulse by the device, wherein the sensing threshold is based upon a measured amplitude of a depolarization event detected through the sensing channel and a noise level measured during a post-ventricular refractory period of the current cardiac cycle;
- and,
- wherein the adjustment of the sensing threshold for a sensing channel is performed in a manner that results in a decrease of the sensing threshold for that channel if no depolarization event was detected during the current cardiac cycle in that channel and a noise level for the channel is unchanged from the previous cardiac cycle.
A cardiac rhythm management device, comprising:
- atrial and ventricular sensing channels for sensing atrial and ventricular electrogram signals, each channel including an electrode and a sense amplifier;
- an atrial threshold detector for detecting p-waves when the sensed atrial electrogram signal exceeds an atrial sensing threshold;
- a ventricular threshold detector for detecting r-waves when the sensed ventricular electrogram signal exceeds a ventricular sensing threshold;
- a pulse generator and associated control circuitry for delivering pacing pulses to the atrium and/or ventricle in response to elapsed time intervals and detected r-waves and p-waves;
- circuitry for adjusting the sensing threshold for a sensing channel for a current cardiac cycle during a refractory period beginning with either detection of an r-wave or delivery of a ventricular pacing pulse by the device, wherein the sensing threshold is based upon a measured amplitude of a depolarization event detected through the sensing channel and a noise level measured during a post-ventricular refractory period of the current cardiac cycle;
- and,
- wherein the adjustment of the sensing threshold for a sensing channel is performed in a manner that results in a decrease of the sensing threshold for that channel if no depolarization event was detected during the current cardiac cycle in that channel and a noise level for the channel is unchanged from the previous cardiac cycle
Dependencies are inferred from the claim text.