Low power apparatus and method to measure complex electrical admittance or impedance

An apparatus for measuring complex electrical admittance and/or complex electrical impedance in animal or human patients comprising:

• two or more electrodes that are adapted to be disposed in the patient in communication with a heart of the patient, the two or more electrodes include a stimulating electrode and a sink electrode that are placed on opposite sides of a left ventricle to cause a sensing field to go across a blood pool in the left ventricle:
• and
• a housing adapted to be disposed in the patient, the housing having disposed in it a stimulator in electrical communication with the two or more electrodes to stimulate with either current or voltage, a sensor in electrical communication with the same stimulating electrode or with additional electrodes to sense a response based on the stimulation of the stimulating electrode, and a signal processor in electrical communication with both the stimulator and the sensor to determine the complex electrical admittance or impedance of the patient, a Discrete Fourier Transform (DFT) is used by the signal processor to extract complex electrical properties to determine heart volume of the heart.

An apparatus for measuring complex electrical admittance and/or complex electrical impedance in animal or human patients comprising:

• two or more electrodes that are adapted to be disposed in the patient in communication with a heart of the patient, the two or more electrodes include a stimulating electrode and a sink electrode that are placed on opposite sides of a left ventricle to cause a sensing field to go across a blood pool in the left ventricle;
• and
• a housing adapted to be disposed in the patient, the housing having disposed in it a stimulator in electrical communication with the two or more electrodes to stimulate with either current or voltage, a sensor in electrical communication with the same stimulating electrodes or with additional electrodes to sense a response based on the stimulation of the stimulating electrode, and a signal processor in electrical communication with both the stimulator and the sensor to determine the complex electrical admittance or impedance of the patient without calculating magnitude and phase in regard to the response to determine heart volume of the heart.