User interface and lock features for positioning multiple components within a body

Disclosed embodiments include apparatuses, systems, and methods for positioning electrodes within a body. In an illustrative embodiment, an apparatus for slidably moving multiple features relative to a sheath inserted into a body and positioned relative to a reference point includes a primary actuator configured to move a primary electrode, a secondary actuator configured to move a secondary electrode, and a control mechanism. The control mechanism is configured to selectively prevent movement of at least one of the primary actuator based on a position of the secondary actuator and of the secondary actuator based on a position of the primary actuator and lock positions of the primary actuator and the secondary actuator.