Catheter assembly, catheter and multi-port introducer for use therewith

An apparatus for mapping a wall of a chamber of a heart having blood therein comprising a first flexible elongate member extending along a longitudinal axis and having proximal and distal extremities, the first flexible elongate member having at least one lumen extending from the proximal extremity to the distal extremity, a plurality of at least three second flexible elongate members having proximal and distal extremities, the proximal extremities of the second flexible elongate members being slidably disposed in the at least one lumen in the first flexible elongate member so that the distal extremities of the second flexible elongate members extend along the longitudinal axis from the distal extremity of the first flexible elongate member, means for joining together the distal extremities of the second flexible elongate members, the second flexible elongate members having portions proximal of the joined together distal extremities which are bowable outwardly relative to the longitudinal axis to an expanded position to engage a portion of the wall of the heart, each of the portions of the second flexible elongate members having a plurality of longitudinally spaced-apart electrodes mounted thereon, the second flexible elongate members being asymmetrically disposed about the longitudinal axis when in the expanded position for forming a mapping assembly to perform fine resolution mapping of the wall of the heart.