An actuating device for a catheter comprising at least one first part and one second part, which are able to more relative to each other, the actuating device comprising: (i) a slide which can be connected to one of said first part and said second part of the catheter; (ii) a slider, which can be actuated for moving said slide and moving said first part and said second part relative to each other; and (iii) a speed-change mechanism, which is set between said slider and said slide.