Configurations are described for assisting in the execution of a percutaneous procedure while protecting the vascular pathway to the operational theater, which may comprise diseased tissue. A railed sheath may be controllably expandable and collapsible, and may comprise two or more elongate rail structures configured to assist in the distribution of loads to associated diseased tissue structures, while also contributing to the deployment of percutaneous tools by maintaining alignment of such tools with the railed catheter and associated anatomy.
