VariSoft allows for independent torque to just the distal spring segment and control of the tip shape, support, and push using the proximal DASH steering handle supplied with VariSoft.
By retracting a restraining core wire, which is attached to the smooth ball welded tip of VariSoft and extending down the central axis of VariSoft to the proximal DASH handle, the physician, with one hand operation of the DASH handle, may control the VariSoft tip characteristics in vivo. Retracting the core is likened to pulling on a guy wire attached to the distal end of VariSoft, thus tensioning the distal spring segment to achieve greater column strength. The greater column strength gives more radial and axial support and thus straightens and adds more push and more support to the entire 35 cm spring tip. This allows VariSoft to exhibit greater strength properties than would normally be available in comparable small diameter guide wires.
When the core is relaxed to allow the tip to resume the user-formed curve, VariSoft is softer and more flexible than standard wires because the entire spring segment is free floating over a smaller diameter core. The core and outer spring taper to a smaller diameter .010" tip resulting in a very supple and very safe guide wire and yet has greater torque than a standard wire because of two means of torque by using the DASH dual collets.
So, by using the central core, VariSoft provides a means for mechanical advantage over fixed wires in being softer when relaxed and firmer when tensioned than standard wires. VariSoft also capitalizes on the mechanical advantage of concentrating the forces of a .014" wire into the smaller .010" tip to enhance crossing tight lesions because of not only a lower profile, but enhanced push and control of the body of a .014" directed to the smaller area of a .010" tip, for a concentration of the force.
Utilizing the DASH handle to control the VariSoft tapered tip is similar to threading a needle by forming a pointed tip in the thread for a lower profile and holding the thread close to the opening to provide greater force/rigidity near where the thread will be advanced through the narrow opening of the needle. The tip of VariSoft is already tapered to .010" and becomes straight to aim toward the opening and more rigid when tensioned by the DASH handle.