An MR compatible steerable sheath with a slidable valve adaptor is provided. The slidable valve adaptor is configured to maintain the steerable shaft in a proximal position such that there is slack in first and second longitudinal movement wires when the valve adaptor is in a first position, and is configured to remove slack from the first and second longitudinal movement wires when the valve adaptor is slidably moved to the second position. Slidable valve adaptor also optionally includes a safety cap that prevents insertion of a catheter into the control handle until the valve adaptor is in the distal position.
