Chronically implantable systems and methods for affecting cardiac contractility and/or relaxation

A method of selecting a combination of electrodes for use in neurostimulation, the method comprising:

• testing combinations of electrodes in an electrode array to identify an atrial capture, wherein the atrial capture is indicated by at least one effect on an atrium;
• excluding electrodes with the atrial capture to result in remaining electrodes of the electrode array;
• testing combinations of the remaining electrodes of the electrode array for effect on cardiac contractility and/or relaxation and monitoring for undesired side effects during the testing of combinations of the remaining electrodes;
• for each combination of the remaining electrodes, during the testing used to establish the effect on cardiac contractility and/or relaxation, measuring impedance across the respective electrode combination using a low-amplitude diagnostic pulse injected concurrently with the testing, and using the measured impedance as a basis for selecting the combination of electrodes;
• selecting a combination of electrodes from the remaining electrodes, wherein the selected combination has both a desired effect on cardiac contractility and/or relaxation and does not have an undesired side effect;
• and
• applying neurostimulation using the selected combination of electrodes to modulate autonomic nerve fibers surrounding a pulmonary artery to provide adjuvant cardiac therapy to a patient with a cardiovascular medical condition.