A clamp (10) having at least first and second elongate clamping portions (2, 4) adapted to be placed on opposite sides of the hollow anatomical structure (40). The first and second elongate clamping portions (2, 4) respectively include ends coupled together with respective resilient urging members (6, 8) configured to urge at least one of the first and second elongate clamping portions (2, 4) toward the other of the first and second elongate clamping portions (2, 4) from an open position into a clamping position to occlude the hollow anatomical structure (40). The clamp (10) is shaped annularly such that it may surround the hollow anatomical structure (40) in the open position and reorient into a flattened shape in the clamping position to occlude the hollow interior of the hollow anatomical structure (40). Apparatus of the invention further include clamp delivery and actuation devices (80, 200) adapted to deploy the clamp (10).