A vascular plug comprises a superstructure expandable from a collapsed percutaneous insertion configuration to an expanded deployment or use configuration. The superstructure incorporates a channel or passageway and a catheter extends through the channel or passageway from a proximal side at least to a distal side of the superstructure. The central channel allows for over-the wire plug delivery and a working aperture for secondary vascular interventions under flow arrest prior to final plug release. The plug includes spring-loaded mechanical elements or clotting-enhancement structure for closing the channel or passageway upon a withdrawal or removal of the catheter from the superstructure.
