"Auto Mode Switch" (AMS) is a feature found in certain dual-chamber pacemakers. It is designed to detect when a person's natural heart rate exceeds the programmed pacemaker rate and automatically switches off ventricular pacing to prevent pacemaker-mediated tachycardia (PMT). By allowing the heart's natural electrical signals to control the heartbeat in such situations, AMS helps improve pacemaker performance and reduce the risk of complications associated with pacing therapy.