Implantable device

An implantable medical device including a test apparatus for an implantable electrode line comprising at least one electrical conductor, the test apparatus comprising:

• a test signal generator for generating an electrical test signal;
• a directional coupler or a circulator connected with the test signal generator for coupling the electrical test signal into the at least one electrical conductor of the electrode line and for decoupling a reflected test signal from the electrical conductor of the electrode line;
• and,
• an evaluation unit connected at least indirectly to the directional coupler or the circulator to detect a fault of the electrode line, wherein the fault comprises an inhomogeneity of the electrode conductor, wherein the evaluation unit compares the reflected signal to a reference signal,
• wherein the directional coupler or the circulator is connected to the electrical conductor of the electrode line via a single-pole, double-throw switch suitable for high frequencies, such that the directional coupler or the circulator, the test signal generator and the evaluation unit are disconnected from the electrical conductor during normal operation of a device connected to the electrical conductor.