applied to the frame to enhance visibility under conventional medical imaging techniques such as x ray fluoroscopy although some frame compositions may have sufficient radiopacity such that radiopaque markers are not necessary or helpful other compositions such as nitinol are only weakly radiopaque with such compositions the presence of one or more markers will assist visualization the use of radiopaque markers is well known in the medical arts and those skilled in the art can readily select and position an appropriate marker or markers for a particular use radiopaque markers formed from metals such as tungsten platinum or gold are particularly preferred for use with frame member 12 such metals can be conveniently supplied in the form of bands and can be applied to the apparatus in other well known manners alternatively instead of applying radiopaque bands to the frame member radiopaque materials can be incorporated into the matrix of the frame member further details of the inventive apparatus are provided in the following discussion of its use in the closure of a patent foramen ovale initially apparatus 10 is elongated or otherwise manipulated in a generally planar fashion as shown in fig2 apparatus 10 is then further elongated or collapsed e g by pulling respective tabs 24 in opposing directions until apparatus 10 has achieved an outer diameter such that it is receivable within the lumen 32 of a conventional delivery catheter such as delivery catheter 30 shown in fig7 delivery.