A sheath introducer (10) for use with a catheter, has a hub (14) and a flexible tube (12) through which the catheter extends, and a lock assembly (30) which has a rotational knob that actuates a plurality of prongs (60) arranged in a radial pattern around a hole (15) in the hub that receives the catheter, wherein the prongs synchronously rotate in one direction to grip the catheter or in the other direction to release the catheter.
