A steerable introducer for a catheter device, the steerable introducer comprising: a body portion having a longitudinal axis extending from a proximal end of the introducer toward a distal end of the introducer, wherein the body portion comprises a flexible distal portion extending to the distal end; a hollow within a part of the body portion for holding the catheter device during a procedure to introduce the catheter device into the body; at least one steering control wire (18, 18') extending axially along the body portion and along at least a part of an axial length of the flexible distal portion; a pair of twisting control wires extending axially along the body portion and along at least a part of an axial length of the flexible distal portion; and a controller for controlling the tension in the steering control wires (18, 18') and in the twisting control wires; wherein the at least one steering control wire (18, 18') has a distal end that is fixed to the flexible distal portion at a first point in a first axial and circumferential position on the flexible distal portion, with the introducer being arranged to allow for tension on the at least one steering control wire (18, 18') to cause a curvature of the flexible distal portion; wherein the pair of twisting control wires each have a distal end, with the twisting control wire distal ends being fixed to the flexible distal portion at second and third points at respective second and third axial and circumferential positions on the flexible distal portion, with the circumferential position of the twisting control wire distal ends being different from each other as well as different from the circumferential position of the steering control wire (18, 18'), and with the introducer being arranged to allow for variations in relative tension between the pair of twisting control wires to cause twisting of the flexible distal portion; wherein the distal end of the introducer can be moved via the twisting movement simultaneously with the steering movement, so that the distal end may shift out-of-plane from the plane of the curvature that would be the result of tension on the at least one steering control wire (18, 18') alone; wherein the controller is arranged to control relative tension between the two twisting control wires; wherein the controller includes a twisting control mechanism comprising: a tensioner for applying tension to both of the pair of twisting control wires, and a tension balancer for varying the relative tension of the two twisting control wires; characterized in that the tension balancer is arranged to vary the relative tension in the two twisting control wires by adjusting a lateral force on each of the two twisting control wires. a body portion having a longitudinal axis extending from a proximal end of the introducer toward a distal end of the introducer, wherein the body portion comprises a flexible distal portion extending to the distal end; a hollow within a part of the body portion for holding the catheter device during a procedure to introduce the catheter device into the body; at least one steering control wire (18, 18') extending axially along the body portion and along at least a part of an axial length of the flexible distal portion; a pair of twisting control wires extending axially along the body portion and along at least a part of an axial length of the flexible distal portion; and a controller for controlling the tension in the steering control wires (18, 18') and in the twisting control wires; wherein the at least one steering control wire (18, 18') has a distal end that is fixed to the flexible distal portion at a first point in a first axial and circumferential position on the flexible distal portion, with the introducer being arranged to allow for tension on the at least one steering control wire (18, 18') to cause a curvature of the flexible distal portion; wherein the pair of twisting control wires each have a distal end, with the twisting control wire distal ends being fixed to the flexible distal portion at second and third points at respective second and third axial and circumferential positions on the flexible distal portion, with the circumferential position of the twisting control wire distal ends being different from each other as well as different from the circumferential position of the steering control wire (18, 18'), and with the introducer being arranged to allow for variations in relative tension between the pair of twisting control wires to cause twisting of the flexible distal portion; wherein the distal end of the introducer can be moved via the twisting movement simultaneously with the steering movement, so that the distal end may shift out-of-plane from the plane of the curvature that would be the result of tension on the at least one steering control wire (18, 18') alone; wherein the controller is arranged to control relative tension between the two twisting control wires; wherein the controller includes a twisting control mechanism comprising: a tensioner for applying tension to both of the pair of twisting control wires, and a tension balancer for varying the relative tension of the two twisting control wires; characterized in that the tension balancer is arranged to vary the relative tension in the two twisting control wires by adjusting a lateral force on each of the two twisting control wires.