Interventional catheter assemblies and components providing improved operational control of interventional catheters and/or operating heads of interventional catheters are provided. In general, controllers incorporate at least two operator selectable control features for controlling operation of the interventional catheter and/or an operating head, and are housed independently of the interventional catheter operating systems and other control systems, which may be provided in a housing located or locatable at a proximal region of the interventional catheter. The controller may be both dockable in and removable from the housing, and is operable in both a docked condition and a removed condition, providing flexibility and mobility in operational control during an interventional procedure.