A catheter includes a handle, a catheter sheath and a stylet received within a lumen of the catheter sheath. A carrier arrangement projects from the distal end of the handle, the carrier arrangement mounting the catheter sheath and at least part of the deflection stylet. The catheter handle includes an adjustment unit having a gear mechanism that controls at least one of the deflection of the distal part of the stylet and the extent of deflection of the distal part of the stylet.