Improved systems for diagnosing and/or treating arrhythmia of a heart makes use of an array of articulation balloons to control movement of a distal portion of a catheter inside the heart, and may be used to align a diagnostic or treatment tool with a target tissue surface region along or adjacent an inner surface of one of the chambers of the heart. The articulation balloons can generate articulation forces at the site of articulation, and the movement may provide greater dexterity than movements induced by transmitting articulation forces proximally along a catheter body that winds through a tortuous vascular pathway. One or more fluid channels may transmit pressure signals that can be used to determine engagement forces between an electrode or other surface near the distal and of an elongate flexible structure and a tissue or other surface, and those same channels may also be used to control inflation of a balloon articulation array, with the pressure signals optionally providing both force and engagement orientation information.
