Abstract: The disclosure provides for a variable stiffness catheter. The catheter may include an inner layer forming an inner lumen, a middle layer surrounding the inner layer, and an outer layer surrounding the middle layer. The middle layer may include an annular lumen and a plurality of strings within the annular lumen, and the plurality of strings may be connected to the inner layer. Applying a vacuum and evacuating the annular lumen of the middle layer alters a frictional force between the inner layer and the outer layer and thereby changes the catheter's flexural rigidity.