Increasing numbers of pulse generators have one or more features that assist in the diagnostic evaluation of the pacing system. Interrogation of programmed parameters, measured lead and battery data, telemetry of event markers, endocardial electrograms, diagnostic data concerning the frequency of pacing and the presence or absence of spontaneous arrhythmias all facilitate the ease with which the pacing system is evaluated and the patient managed. The utility of these features is illustrated from five separate cases demonstrating the value of the individual features and how they may complement one another in extremely complicated pacing system problems.