A guide device establishes a guide passage through a guide tube, through which an operative tool can be deployed into an interior body region for use. A steering assembly, in use, deflects or bends the distal end region of the guide tube, so that the operative tool can be placed in a desired orientation with respect to tissue. The steering assembly is desirable configured for single handed operation by the clinician. The steering assembly is also desirably configured to provide a mechanical advantage sufficient to translate relatively small increments of clinician control into relatively larger increments of guide tube deflection. In one arrangement, the steering assembly includes a rack and pinion linkage system. In another arrangement, the steering assembly includes a pivoting lever system.
