A catheter (12) includes a flexible tubing and a control handle (16) proximal of the flexible tubing. The control handle has a barrel housing (80) and a piston (54) in a telescopic configuration. The piston has a thumb control (56) for deflecting the tubing and a tension adjustment assembly (90) which allows the user to lock the piston, reposition the piston and control the amount of force required to move the piston. The tension adjustment assembly includes a set screw (96) and an adjustable knob (94).
