An improved catheter is provided that is particularly useful for mapping the pulmonary vein and other tubular regions of or near the heart. The catheter comprises an elongated catheter body having a proximal end, a distal end and at least one lumen extending longitudinally therethrough. A mapping assembly is mounted at the distal end of the catheter body and comprises a stem and at least two spines. The spines are moveable between a collapsed position, where each spine has a distal end attached to the stem, and a free proximal end positioned generally against the stem, and an expanded position, where the free proximal end of each spine extends outwardly from the stem. Each spine carries at least one electrode.