An MRI-compatible electronic medical therapy system is provided for temporarily preventing current flow through an implanted lead wire in the presence of an induced radio frequency, magnetic, or static field. One or more normally closed switches are disposed in series between the AIMD and the one or more distal electrodes. The switch may be incorporated in the AIMD, lead wire, or within or adjacent to the electrode. The switch remains closed during normal AIMD-related therapy, but temporarily opens in the presence of an induced radio frequency, magnetic, or static field so as to prevent current flow through the electrode and lead wire. The switches prevent current from circulating that could be induced by a medical therapeutic diagnostic device, which can cause overheating of lead wires, excessive currents or temperatures and tissue damage.