Abstract: A system and method is provided for reliably indicating that an implantable medical device is in need of replacement. An implantable medical device includes a battery and a replacement indicator timer. The battery provides power to the implantable medical device. The replacement indicator timer counts a replacement time period to a determined replacement date for the implantable medical device. The replacement indicator timer starts the counting when an operational characteristic of the battery reaches a selected value.

Abstract: In bi-ventricular pacing devices (including CRT devices) analysis of myocardial electrogram signals in one ventricle (e.g., a left ventricle, or “LV”) can be used to infer capture or loss-of-capture (LOC) of an earlier stimulus pulse in the same ventricle, on a continuous (every pacing cycle), triggered, aperiodic and/or periodic basis. Rather than using an evoked-response principle as has been the basis of capture detection in prior art and other systems, a principle employed via the present invention uses evidence of inter-ventricular conduction (i.e., from the opposite chamber) and/or atrio-ventricular conduction as evidence of LOC, since a non-capturing pacing stimulus provided to a first chamber will allow the myocardial tissue of the first chamber to remain non-refractory and thus inter-ventricular and atrio-ventricular wavefront propagation and conduction can commence and be detected thereby revealing whether LOC has occurred.