A modular handle assembly (20, 120) for supporting and controlling a steerable catheter (22) includes a handle portion which extends along an axis for being secured about a portion of the steerable catheter. The modular handle assembly includes at least one barrel (80) that is rotatably connected to the handle portion for rotation about said axis and at least one actuation screw shaft (112) that is disposed within said handle portion and which extends through the barrel for connection with the deflection wire of the steerable catheter. At least one pinion gear (122) is disposed radially between the actuation screw shaft and the barrel and is threadedly interconnected with the actuation screw shaft and the barrel for translating rotational movement of the barrel about the axis into axial movement of the actuation screw shaft to provide for movement of the deflection wire to curl the steerable catheter.
