An irrigated balloon catheter, includes a balloon carrying contact electrodes,wherein a user can vary the balloon's configuration by manipulating anelongatedexpander that extends along the catheter and through the balloon's interior,with its distalend coupled to a distal end of the balloon. The expander may pass through anirrigationlumen to save on space within the catheter, and the expander itself may behollow inproviding a lumen for cables or lead wires. The expander may include flexureslits forincreased flexibility. The distal end of the balloon includes a housing forcomponents,e.g., a position sensor. The distal end of the balloon and the manner by whichthe balloonmembrane is attached to the housing present a generally flat atraumaticsurface suitablefor direct head-on contact with tissue. Longitudinal spines extend along theouter surfaceof the balloon to provide support.
