A helical element for insertion into tissue comprises a helical element
having an insertion end, a protruding end and an open central area within
the wire, rods, filaments, cables or the like that form the helix. The
helical element has at least its insertion end covered by a cap of a
water-soluble or water-dispersible composition. The cap is provided with a
surface shape in a cross-section in which surface variations are present
in the cross-section which create a surface orientation where a line from
the center of the cross-section can intersect the surface, and a line
perpendicular to said radius at a point of intersection with said surface
forms four quadrants, three of said quadrants containing water-soluble or
water-dispersible cap material. There is either a hollow area within the
composition within the open central area or the material is more porous
than the remaining material. The helical element preferably comprises an
electrical lead, such as a positive endocardial lead, with an electrode at
the protruding or distal end of the lead.
The helical element may comprise any biocompatable material with sufficient
structural integrity to provide a secure attachment to tissue in a
patient. Where the helical element is also to provide an active
(electrically active) function, the composition of the helical element
should also be electrically conductive.