A catheter handle assembly comprising a handle body with a proximal end and a distal end with a passage extending therebetween. An adjustment unit disposed in the passage of the handle body and the adjustment unit comprising a gear mechanism that acts on the on a deflection stylet for adjusting deflection of the distal part of the deflection stylet. The gear mechanism comprises a first rack, a second rack and a pinion such that rotation of the pinion causes relative movement of the first rack and the second rack in opposing directions.
