A distal end of a flexible catheter can be selectively deflected in a desired direction by actuating one or more actuators that extend outwardly of an exterior surface of the catheter. Each actuator can be a balloon disposed within a non-extendible balloon or sheath. Inflation of one (or both) of the balloon and the non-extendible balloon with a pressurized fluid can deflect the distal tip of the catheter. Another actuator embodiment comprises a strip of a bimorph material that bends outwardly when actuated, e.g., by heat, applying a force against adjacent tissue to deflect the distal tip. Yet another embodiment includes a strip of material that shortens when heated and can be coupled to a balloon that is inflated outwardly to increase a radial moment arm of the force applied thereby, relative to a neutral axis of the catheter, to more readily deflect the distal tip.