Abstract: A steerable stylet and manipulative handle assembly especially adapted for guiding the introduction of an endocardial pacing or cardioversion/defibrillation lead or a catheter to a desired location in a patient's cardiovascular system. The steerable stylet or catheter designed to be introduced into the lumen of a lead comprises an outer, elongated tubular member of a length sufficient to extend through the length of the lead or catheter from its proximal opening to the distal end thereof, a traction element or pull wire extending generally through the length of the tubular member and within its lumen except for a predetermined distance in the distal portion thereof, and a manipulative handle coupled to the proximal ends of the tubular member and wire which may be employed with one hand to both rotate the tubular member and impart a continuously variable curve in the distal portion thereof.