A catheter maps an electrical conduction pattern in an annular region of a heart. The catheter has a tubular shaft that has a pre-shaped curved distal section adjacent the distal end thereof, and at least one lumen extending between the distal end and the proximal end of the shaft, with a plurality of electrodes disposed on the distal section. A handle is attached to the proximal end of the shaft, with a steering mechanism provided at the handle for adjusting the curvature of the distal section, and a deflection mechanism provided at the handle for deflecting the distal section. The electrodes are positioned in a parallel plane separate from the shaft when the distal section is undeflected.