Abstract: In one embodiment, a medical system includes a catheter configured to be inserted into a chamber of a heart of a living subject, and including a distal end including catheter electrodes configured to contact tissue at respective locations within the chamber of the heart, at least one position sensor configured to provide at least one position signal indicative of a position of the distal end, a display, and processing circuitry configured to compute the position of the distal end of the catheter responsively to the at least one position signal, render to the display a 3D anatomical map of the chamber of the heart and a 3D representation of the distal end of the catheter, and render to the display over at least part of the map, at least one intracardiac electrogram trace representing electrical activity in the tissue that is sensed by at least one of the catheter electrodes.