A system for maintaining patency of a body lumen may include a first endoprosthesis configured to shift from a straightened configuration to a helical configuration defining a plurality of loops, and a second endoprosthesis configured to shift from a radially collapsed configuration toward a radially expanded configuration. The plurality of loops defines a passage having an inner diameter. At least a portion of the second endoprosthesis is disposed within the passage in the radially expanded configuration. A method of maintaining patency of a body lumen may include advancing a first endoprosthesis into a first body lumen in a straightened configuration, deploying the first endoprosthesis within the first body lumen in a helical configuration defining a plurality of loops, advancing a second endoprosthesis into the first body lumen in a radially collapsed configuration, and shifting the second endoprosthesis to a radially expanded configuration within the plurality of loops.