Modern implantable cardiac stimulation devices include processing and data storage capabilities that may be exploited to track myocardial condition and autonomic tone. In addition, an annular groove recessed radially inward is formed on the outer peripheral surface of the shaft in a location opposing the region where the upper herringbone grooves and the lower herringbone grooves adjoin. The support tabs provide a clearance gap in which at least portions of the plurality of electrical contacts reside. A controller is configured to monitor the signal output by the sensor and, responsive to a deviation of a value of the signal from an acceptable value for the signal, to execute an error recovery instruction set at least once.