Cardiac stimulation devices and methods for measuring impedances associated with the left side of the heart

An implantable cardiac impedance measuring device comprising:

• means for providing an electrical current between a first pair of electrodes that are configured for placement internally in a patient and in operable association with the patient's heart;
• means for measuring a voltage, responsive to the electrical current, between a second pair of electrodes that are configured for placement internally of a patient and in operable association with the patient's heart;
• means for calculating, from the electrical current and a corresponding measured voltage, an impedance;
• and
• switch means for programmably selecting at least one electrode of the first and second pair of electrodes so that the at least one electrode comprises a left side heart electrode, the switch means enabling an impedance to be calculated that is associated with the patient's left side heart.

A cardiac stimulation device comprising:

• one or more computer-readable media;
• one or more processors;
• and
• instructions embodied on the one or more computer-readable media which, when executed by the one or more processors, cause the one or more processors to calculate an impedance using at least one left side heart electrode.

A cardiac stimulation device comprising:

• one or more computer-readable media;
• one or more processors;
• and
• instructions embodied on the one or more computer-readable media which, when executed by the one or more processors, cause the one or more processors to calculate an impedance using a multi-polar electrode configuration with at least one left side heart electrode.

A method of measuring an impedance using a cardiac stimulation device comprising:

• establishing a current path between a first pair of electrodes configured for use internally of a patient;
• measuring a voltage between a second pair of electrodes configured for use internally in a patient, at least one electrode of the second pair comprising a left side heart electrode;
• and
• calculating an impedance based upon the established current and the measured voltage.

A method of assessing a patient's cardiac condition comprising:

• establishing a current path between a first pair of electrodes configured for use internally in a patient;
• measuring a voltage between a second pair of electrodes configured for use internally of a patient, at least one electrode of the second pair comprising a left side heart electrode;
• calculating an impedance based upon the established current and the measured voltage;
• and
• based on the calculated impedance, determining one or more physiological parameters for assessing a patient's cardiac condition.