A system for treating a patient, comprising: a device (405, 410) for positioning within the lumen of a blood vessel, adjacent to the mouth of an aneurysm extending from the lumen of the blood vessel, for causing thrombosis of the aneurysm while maintaining substantially normal blood flow through the blood vessel, the device comprising: a single closed loop of elastic filament configurable between: (i) a first longitudinally-expanded, radially and laterally-contracted configuration for movement along a blood vessel, the first configuration providing two parallel lengths of the closed loop of elastic filament; and (ii) a second longitudinally-contracted, radially and laterally-expanded configuration for lodging within a blood vessel, the second configuration providing (a) a single flow-restricting face sized and configured so as to cover the mouth of the aneurysm and obstruct blood flow to the aneurysm while permitting substantially normal blood flow through the blood vessel when the flow-restricting face is positioned over the mouth of the aneurysm, with the degree of obstruction at the mouth of the aneurysm being such that the aneurysm thromboses when the flow-restricting face is positioned over the mouth of the aneurysm, the single, flow-restricting face comprising a plurality of lengths of the closed loop of elastic filament disposed in close proximity to one another in a switchback configuration, wherein the flow restricting face comprises a plurality of parallel lengths of elastic filament, with adjacent parallel lengths of elastic filament being connected by end returns, and (b) an open frame for spanning the blood vessel and bearing against opposing anatomy so as to support flow-restricting face adjacent the mouth of the aneurysm, the open frame comprising at least one leg wherein the at least one leg is configured so as to maintain substantially normal blood flow through the blood vessel. (i) a first longitudinally-expanded, radially and laterally-contracted configuration for movement along a blood vessel, the first configuration providing two parallel lengths of the closed loop of elastic filament; and (ii) a second longitudinally-contracted, radially and laterally-expanded configuration for lodging within a blood vessel, the second configuration providing (a) a single flow-restricting face sized and configured so as to cover the mouth of the aneurysm and obstruct blood flow to the aneurysm while permitting substantially normal blood flow through the blood vessel when the flow-restricting face is positioned over the mouth of the aneurysm, with the degree of obstruction at the mouth of the aneurysm being such that the aneurysm thromboses when the flow-restricting face is positioned over the mouth of the aneurysm, the single, flow-restricting face comprising a plurality of lengths of the closed loop of elastic filament disposed in close proximity to one another in a switchback configuration, wherein the flow restricting face comprises a plurality of parallel lengths of elastic filament, with adjacent parallel lengths of elastic filament being connected by end returns, and (b) an open frame for spanning the blood vessel and bearing against opposing anatomy so as to support flow-restricting face adjacent the mouth of the aneurysm, the open frame comprising at least one leg wherein the at least one leg is configured so as to maintain substantially normal blood flow through the blood vessel.