An implantable medical device (IMD) is provided comprising inputs configured to be coupled to leads having electrodes thereon, wherein combinations of the electrodes are associated with respective active sensing vector. The IMD further comprises an impedance measurement module to collect multiple measured impedances between corresponding combinations of the electrodes. The IMD further includes an impedance derivation module to calculate a derived impedance for at least one pseudo sensing vector based on the measured impedances, wherein the pseudo sensing vector extends to or from at least one pseudo sensing site.
