A lead body adapted for in-vivo implantation in a living subject includes a proximal end configured for electrical and mechanical connection to a therapy or a monitoring device, and a distal end. A collar is disposed at the distal end of the lead body, and a casing is disposed within the collar and is translatable along a central longitudinal axis of the collar. At least one electrical conductor extends substantially the length of the lead body, and an electronic component is disposed within the casing and conductively coupled to the electrical conductor. An electrode is mechanically connected to the casing and conductively coupled to the electronic component. A seal is disposed between the casing assembly and the collar to prevent passage of ionic fluid into the lead body through its distal end.
