Systems and methods for assessing the sphericity and dimensional extent of heart chambers for use with an implantable medical device

A method for use with an implantable medical device for implant within a patient, the method comprising:

• taking a first measurement of the impedance between an electrode of a first lead and a first of a plurality of electrodes of a second lead and taking a first measurement of the impedance between the electrode of the first lead and a second of a plurality of electrodes of the second lead, with a portion of the first lead being implanted within the right ventricle of the heart of the patient and a proximal end of the first lead being connected to the implantable medical device, and a portion of the second lead being implanted at least proximate the left ventricle of the heart of the patient, and a proximal end of the second lead being connected to the implantable medical device;
• taking, at a time subsequent to the step of taking the first measurement, a second measurement of the impedance between the electrode of the first lead and the first of a plurality of electrodes of the second lead, and taking, at a time subsequent to the step of taking the first measurement, a second measurement of the impedance between the electrode of the first lead and the second of a plurality of electrodes of the second lead;
• determining, if any, change in impedance from the first measured impedance and the second measure impedance that was taken between the electrode of the first lead and the first of a plurality of electrodes of the second lead, and if a change is determined, tracking the change of impedance between the electrode of the first lead and the first of a plurality of electrodes of the second lead;
• determining, if any, change in impedance from the first measured impedance and the second measure impedance that was taken between the electrode of the first lead and the second of a plurality of electrodes of the second lead, and if a change is determined, tracking the change of the impedance between the electrode of the first lead and the second of a plurality of electrodes of the second lead;
• repeating at least one time both of the steps of taking impedance measurements and the steps of determining change in impedance;
• and
• if changes are tracked, tracking the progression of the shape of the left ventricular chamber of the patient between an ellipsoid shape and a spherical shape based upon the tracked change of impedance measurements, and controlling at least one of a plurality of functions of the implantable medical device within the patient based upon the tracked progression of the shape of the left ventricular chamber.