Interventional device for RF ablation for use in a RF electrical and/or magnetic field, comprising: - an ablation catheter or probe with an ablation electrode for delivering RF ablation power, and - a transmission path connected with the ablation catheter or probe, comprising at least two line segments (104', 104") which are electrically coupled by means of at least one coupling element comprising a high pass filter characteristic so that - common mode currents induced in the transmission path by the RF field of a first frequency to which the transmission path is exposed, are at least substantially blocked and - the RF ablation power having a predetermined second RF frequency (f A), which is higher than the first frequency, is at least substantially, or to an extent which is necessary for a desired ablating of a tissue, transmitted over the transmission path and - an MR/RF microcoil configured to receive MR signals and/or to transmit RF signals, for active and /or passive tracking, guiding and or visualisation of the catheter or probe in a MR image generated by an MR imaging system and - an MR / RF receiver/transmitter which is connected with the transmission path and configured to receive MR signals detected by the MR/RF microcoil and / or to generate RF signals to be transmitted by the MR/RF microcoil and - an RF amplifier configured to generate the RF ablation power at the second RF frequency (f A), which RF amplifier is connected with the transmission path for conveying the RF ablation power in the form of common mode currents to the ablation electrode and - a connection unit configured to connect the MR/RF receiver/transmitter and the RF amplifier with the transmission path and further configured to perform: - a one way common mode connection for the RF ablation power to the ablation electrode, - a differential mode connection for the MR/RF signals to/from the MR receiver/transmitter simultaneously with the one way common mode connection and - an isolation of the MR/RF receiver/transmitter 108 from the RF ablation power generated by the RF amplifier. - an ablation catheter or probe with an ablation electrode for delivering RF ablation power, and - a transmission path connected with the ablation catheter or probe, comprising at least two line segments (104', 104") which are electrically coupled by means of at least one coupling element comprising a high pass filter characteristic so that - common mode currents induced in the transmission path by the RF field of a first frequency to which the transmission path is exposed, are at least substantially blocked and - the RF ablation power having a predetermined second RF frequency (f A), which is higher than the first frequency, is at least substantially, or to an extent which is necessary for a desired ablating of a tissue, transmitted over the transmission path and - an MR/RF microcoil configured to receive MR signals and/or to transmit RF signals, for active and /or passive tracking, guiding and or visualisation of the catheter or probe in a MR image generated by an MR imaging system and - an MR / RF receiver/transmitter which is connected with the transmission path and configured to receive MR signals detected by the MR/RF microcoil and / or to generate RF signals to be transmitted by the MR/RF microcoil and - an RF amplifier configured to generate the RF ablation power at the second RF frequency (f A), which RF amplifier is connected with the transmission path for conveying the RF ablation power in the form of common mode currents to the ablation electrode and - a connection unit configured to connect the MR/RF receiver/transmitter and the RF amplifier with the transmission path and further configured to perform: - a one way common mode connection for the RF ablation power to the ablation electrode, - a differential mode connection for the MR/RF signals to/from the MR receiver/transmitter simultaneously with the one way common mode connection and - an isolation of the MR/RF receiver/transmitter 108 from the RF ablation power generated by the RF amplifier. - a one way common mode connection for the RF ablation power to the ablation electrode, - a differential mode connection for the MR/RF signals to/from the MR receiver/transmitter simultaneously with the one way common mode connection and - an isolation of the MR/RF receiver/transmitter 108 from the RF ablation power generated by the RF amplifier.