An implantable medical device (IMD) includes a housing that is configured to be positioned at least in part in a chamber of a heart, and in some cases, in a right ventricle (RV) proximate an RV facing side of the ventricular septum of the heart. When so provided, an RV electrode may be fixed relative to the housing to be proximate the RV facing side of the ventricular septum. An LV electrode may be spaced a distance from the RV electrode and the housing such that the LV electrode is positioned at least partially within the ventricular septum. An LV electrode position adjustment assembly may be used to adjust the depth at which the LV electrode is positioned within the ventricular septum.
