An apparatus includes a sensing unit and controlcircuitry. The sensing unit is connected to a channelthat delivers Electro-Physiological (EP) signals from acardiac catheter to an EP recording system and pacingsignals from the EP recording system to the catheter. Thesensing unit is configured to automatically identify timeintervals during which the pacing signals are delivered.The control circuitry is configured to route the EPsignals on the channel from the catheter to the EPrecording system via an intervening system that isdetrimental to the pacing signals, to switch the channelto an alternate path that bypasses the intervening systemduring the identified time intervals, and to route thepacing signals from the EP recording system to thecardiac catheter over the alternate path.
