QUANTIFYING SYSTOLIC AND DIASTOLIC CARDIAC PERFORMANCE FROM DYNAMIC IMPEDANCE WAVEFORMS
First Claim
1. A method of controlling a cardiac resynchronization therapy (CRT) device comprising:
- measuring a dynamic intrathoracic impedance from three or more electrode sites, wherein at least one electrode site is a non-intracardiac electrode site;
determining a control parameter associated with the dynamic intracardiac impedance data of a patient;
measuring a pulmonary impedance using the non-intracardiac electrode site and another of said three or more electrode sites;
reducing the control parameter based upon the thoracic impedance; and
setting an operational parameter of said CRT device based on a difference between said control parameter and a reference value.
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Accused Products
Abstract
The present invention is related to implantable cardiac devices such as pacemakers and defibrillators that deliver cardiac resynchronization therapy (CRT), and to a method of optimizing acquisition of multi-vector impedance signals from electrodes present on implanted lead systems. Acquired impedance signals associated with dynamic intracardiac impedance are related to specific time frames of the cardiac cycle as to derive indices representative of systolic and diastolic cardiac performance. The impedance signals are further adjusted by non-dynamic or static impedance signals associated with pulmonary impedance as to derive composite indices representative of cardiac performance and pulmonary vascular congestion. The pulmonary impedance signals are preferably obtained during relative periods of apnea in a patient.
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Citations
20 Claims
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1. A method of controlling a cardiac resynchronization therapy (CRT) device comprising:
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measuring a dynamic intrathoracic impedance from three or more electrode sites, wherein at least one electrode site is a non-intracardiac electrode site;
determining a control parameter associated with the dynamic intracardiac impedance data of a patient;
measuring a pulmonary impedance using the non-intracardiac electrode site and another of said three or more electrode sites;
reducing the control parameter based upon the thoracic impedance; and
setting an operational parameter of said CRT device based on a difference between said control parameter and a reference value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A cardiac resynchronization therapy (CRT) system comprising:
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a cardiac resynchronization therapy (CRT) device configured to;
a) apply therapy to a patient based on a plurality of operational parameters;
b) detect a dynamic intrathoracic impedance of the patient, wherein the dynamic intrathoracic impedance comprises a dynamic intracardiac impedance component and a pulmonary impedance component; and
c) calculate a control parameter from the dynamic intracardiac impedance component and a pulmonary impedance component;
d) evaluate if said control parameter is acceptable; and
e) set said operational parameters based on said control parameter, if said control parameter is found acceptable. - View Dependent Claims (19, 20)
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Specification