A steerable catheter comprises a mobile tube and an intermediate tube, coaxial with each other, which extend from a proximal end to a distal end of the catheter and are telescopically mounted into each other with possibility of mutual rotation and axial translation. The mobile tube comprises a central lumen extending from the proximal end to the distal end. The intermediate tube comprises, along its whole length, a longitudinal notch radially offset in a direction of offset with respect to the axis of the steerable catheter and extending axially from the proximal end to the distal end. The longitudinal notch contains a cable adapted to undergo a traction exerted from the proximal end, the traction generating a bending of the steerable catheter directed towards the offset direction. The steerable catheter further comprises around the intermediate tube a sealed external sheath surrounding the intermediate tube over its periphery and covering the longitudinal notch over its length.