Implantable cardiac stimulation system providing autocapture and lead impedance assessment and method

Abstract

An implantable cardiac stimulation system provides autocapture assessment and lead impedance surveillance. The system includes a pulse generator that provides pacing stimulation pulses and a lead system including a plurality of electrodes that provide a plurality of different electrode configurations. The system further includes a switch that selectively couples the pulse generator to any one of the plurality of pacing electrode configurations and an autocapture circuit that performs autocapture tests with the pulse generator. The autocapture circuit includes a capture detector that detects evoked responses with an evoked response electrode configuration. When there is a failure to detect an evoked response, an impedance measuring circuit measures the lead impedance of the evoked response electrode configuration. If the measured lead impedance is outside of a given range, the switch couples the pulse generator to an electrode configuration other than the evoked response electrode configuration. Thereafter, the autocapture circuit performs a further autocapture and impedance measuring test or sets the pacing output to a level which assures capture.