Cardiac Pacemakers, Inc.

St. Jude Medical, Cardiology Division, Inc.

Boyce Moon

Jeffrey E Stahmann

Troy Terrance Tegg

John D Hatlestad

Jesse W Hartley

James O Gilkerson

Derek C Sutermeister

Yongxing Zhang

Eric Steven Olson

Yunlong Zhang

Israel A Byrd

John Tranter

Jake Daly

Kenneth Drew

A system to measure intracardiac impedance includes implantable electrodes and a medical device. The electrodes sense electrical signals of a heart of a subject. The medical device includes a cardiac signal sensing circuit coupled to the implantable electrodes, an impedance measurement circuit coupled to the same or different implantable electrodes, and a controller circuit coupled to the cardiac signal sensing circuit and the impedance measurement circuit. The cardiac signal sensing circuit provides a sensed cardiac signal. The impedance measurement circuit senses intracardiac impedance between the electrodes to obtain an intracardiac impedance signal. The controller circuit determines cardiac cycles of the subject using the sensed cardiac signal, and detects tachyarrhythmia using cardiac-cycle to cardiac-cycle changes in a plurality of intracardiac impedance parameters obtained from the intracardiac impedance signal.

Intracardiac impedance and its applications

This document discusses, among other things, a cardiac rhythm management device or other implantable medical device that uses thoracic impedance to determine how much fluid is present in the thorax, such as for detecting or predicting congestive heart failure, pulmonary edema, pleural effusion, hypotension, or the like. The thoracic fluid amount determined from the thoracic impedance is compensated for changes in blood resistivity, which may result from changes in hematocrit level or other factors. The blood-resistivity-compensated thoracic fluid amount can be stored in the device or transmitted to an external device for storage or display. The blood-resistivity-compensated thoracic fluid amount can also be used to adjust a cardiac pacing, cardiac resynchronization, or other cardiac rhythm management or other therapy to the patient. This document also discusses applications of the devices and methods for predicting or indicating anemia.

Thoracic impedance detection with blood resistivity compensation

A system includes an implantable medical device that includes a trans-thoracic impedance measurement circuit providing a trans-thoracic impedance signal of a subject. A controller is coupled to the trans-thoracic impedance circuit. The controller extracts a respiration signal from the trans-thoracic impedance signal, measures a breathing volume of the subject using the amplitude of the respiration signal and a breathing volume calibration factor, computes an adjusted breathing volume calibration factor using a reference baseline value of the trans-thoracic impedance and a measured baseline value of the trans-thoracic impedance, and computes a calibrated breathing volume using the adjusted breathing volume calibration factor.

Calibration of impedance monitoring of respiratory volumes using thoracic D.C. impedance

Growing community of inventors

Ham Lake, MN, United States of America

Boyce Moon