Interventional catheter assemblies, control systems and operating methods

An interventional catheter assembly has an operating head and catheter system that are inserted and navigated within a patient's body while an operator controls the system externally of the operating head. An operating head is positioned at or near a distal end of the catheter system and coupled to a drive shaft and drive system for rotation. A guidewire brake control system interrupt prevents the drive system from being actuated when the guidewire brake is in a released position, and a selectable guidewire brake interrupt override control permits an operator to translate and/or rotate the drive shaft and operating head while the guidewire is simultaneously moved. This allows withdrawal of the guide wire and the operating head from the target site while rotating the operating head.