The present invention relates to a medical system using an interventional elongated medical device having an optical fiber configured for optical shape sensing of the medical device. The system comprises a detection unit configured to detect a confined manipulation section along the medical device for manipulation by a user without an interaction interface arranged on the medical device and an analysis unit configured to analyze a user manipulation applied to the manipulation section based on optical shape sensing of the medical device in the manipulation section and to trigger an event in the medical system, if the analysis unit identifies the user manipulation in the manipulation section as a specific manipulation associated with the event to be triggered.