Configurations are described for assisting execution of a percutaneous procedure while protecting the vascular pathway to the operational theater. One embodiment is directed to a system for deploying a device to a distal location across a diseased vessel, comprising a sheath comprising an expandable distal portion comprising a porous wall defining a lumen therethrough, the distal portion having a collapsed configuration, wherein the sheath has a first cross sectional outer diameter and a first lumen inner diameter, and an expanded configuration, wherein the sheath has a second cross sectional outer diameter and a second lumen inner diameter； wherein in the collapsed configuration, the sheath is configured to be advanced across at least a portion of the diseased vessel to a position adjacent the distal location without substantial size interference between the first cross sectional outer diameter of the sheath and an inner diameter profile of a lumen of the vessel.
