Rate adaptive cardiac rhythm management device using transthoracic impedance

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....

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Bibliographic Details
Main Authors COHEN; MARC H, REEDSTROM; SCOTT A, STESSMAN; NICHOLAS J, HARTLEY; JESSE W, NELSON; JAMES P, CHECK; STEVEN D
Format Patent
LanguageEnglish
Published 12.12.2000
Edition7
Subjects
ELECTROTHERAPY
HUMAN NECESSITIES
HYGIENE
MAGNETOTHERAPY
MEDICAL OR VETERINARY SCIENCE
RADIATION THERAPY
ULTRASOUND THERAPY
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Summary: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.
Bibliography:Application Number: US19990316690