Patent ID: 8170667

Claim:
A system, comprising: an implantable cardiac rhythm management (CRM) device including: a device body encapsulating a CRM circuit upgradeable from a monitoring circuit to a pacing circuit after the implantation of the implantable CRM device and including a sensing circuit adapted to sense an electrogram, the CRM circuit configured to operate as the monitoring circuit and the pacing circuit at different times, the pacing circuit configured to be inactive when the CRM circuit is configured to be the monitoring circuit and capable of producing pacing pulses when the CRM circuit is configured to be the pacing circuit, the sensing circuit having a set of cutoff frequencies for filtering the sensed electrogram, the set of cutoff frequencies programmed to be a first set of values and a second set of values at the different times, the first set of values suitable for far-field electrogram sensing, the second set of values suitable for intracardiac electrogram sensing and different from the first set of values; and a header attached to the device body, the header including at least one connector providing for electrical connection to the CRM circuit; and an implantable adaptor adapted to be connected to the header, the implantable adaptor including a first electrode adapted to sense a far-field electrogram.