Cardiac Pacemakers, Inc.

Marc H Cohen

Jesse W Hartley

Nicholas J Stessman

James P Nelson

Steven D Check

Scott A Reedstrom

A cardiac rhythm management (CRM) device detects transthoracic impedance, extracts ventilation or other information, and adjusts a delivery rate of the CRM therapy accordingly. A four-phase sequence of alternating direction current pulse stimuli is periodically delivered to a patient's thorax. A transthoracic impedance signal is extracted using a weighted demodulation. Signal processing extracts ventilation information and removes cardiac stroke information using an adaptive lowpass filter. The adaptive filter cutoff frequency is based on the patient's heart rate; a higher cutoff frequency is provided for higher heart rates. Peak/valley detection indicates tidal volume, which is integrated to extract minute ventilation (MV). Short and long term averages are formed and compared to establish a MV indicated rate. Rate adjustment ignores MV information when a noise-measurement exceeds a threshold. An interference avoidance circuit delays delivery of the stimuli when telemetry pulses or other interfering signals are detected.

Growing community of inventors

Baltimore, MD, United States of America

Marc H Cohen