EXTERNAL SUPPORT FOR ELONGATED BODILY VESSELS

1 . An external support implant for unbound covering of a blood vessel graft in a peripheral vascular bypass system, the external support implant comprises:

an elongate body having a longitudinal axis, and an interior collapsible upon an exterior of the blood vessel graft, said elongate body comprises a tubular fabric having intertwined coiled compression springs configured for elastically resisting longitudinal compression of said elongate body from a relaxed length, when said compression springs are stressed, and for elastically increasing diameter of said elongate body when said compression springs are subjected to said longitudinal compression.

2 . The external support implant of claim 1 , wherein said tubular fabric comprises a braid and said coiled compression springs are intertwined to form said braid.

3 . The external support implant of claim 1 , wherein said coiled compression springs are made of a cobalt-chromium alloy.

4 . The external support implant of claim 1 , wherein said relaxed length is at least about 20 cm.

5 . The external support implant of claim 1 , wherein said relaxed length corresponds to a distance extending along part or all of length between two ends of the blood vessel graft when anastomosed.

6 . The external support implant of claim 1 , wherein said compression springs are configured for confining ratio of per cent change in length per unit change in diameter of a radially compressed segment of said elongated body, to a range of between about 2%/mm and about 20%/mm, relative to said length and said diameter of said elongate body when having said relaxed length.

7 . The external support implant of claim 1 , wherein, when said elongate body has said relaxed length, said compression springs are configured for said elastically increasing of said elongate body diameter from a graft covering diameter having a range of between about 4 mm and about 7 mm, to a graft sleeving diameter.

8 . The external support implant of claim 7 , wherein said compression springs are configured for said elastically increasing of said elongate body diameter by an amount equal to or more than about 20%, when changing from said graft covering diameter to said graft sleeving diameter.

9 . The external support implant of claim 7 , wherein said compression springs are configured for said elastically increasing of said elongate body diameter by an amount equal to or less than about 10%, when length of said elongate body decreases by an amount equal to about 5% during the covering of the blood vessel graft.

10 . The external support implant of claim 7 , configured for covering a calf-harvested vein graft, wherein said graft covering diameter is, on average, about 4 mm, and said graft sleeving diameter has a range of between about 5 mm and about 6 mm.

11 . The external support implant of claim 7 , configured for covering a thigh-harvested vein graft, wherein said graft covering diameter is, on average, about 6 mm, and said graft sleeving diameter has a range of between about 8 mm and about 12 mm.

12 . The external support implant of claim 7 , wherein said compression springs are configured for elastically decreasing said relaxed length of said elongate body by at least about 50%, during said elastically increasing of said elongate body diameter from said graft covering diameter to said graft sleeving diameter.

13 . The external support implant of claim 12 , wherein said relaxed length is decreased by at least about 30% when said elongate body diameter elastically increases by about 20%.

14 . The external support implant of claim 1 , wherein said tubular fabric includes a plurality of intertwined wires in a range of between about 20 and about 60 of said intertwined wires.

15 . The external support implant of claim 1 , wherein said tubular fabric includes a plurality of said compression springs in a range of between about 40 and about 45 of said compression springs.

16 . The external support implant of claim 1 , wherein, when said elongate body has said relaxed length, said tubular fabric includes intertwined wires forming a braiding angle in a range of between about 80 degrees and about 110 degrees.

17 . The external support implant of claim 16 , wherein, when said elongate body has said relaxed length, said braiding angle is about 95 degrees.

18 . The external support implant of claim 1 , wherein said tubular fabric includes intertwined wires having a diameter in a range of between about 30 micrometers and about 65 micrometers.

19 . The external support implant of claim 1 , wherein said compression springs are comprised of intertwined wires each having a diameter of about 50 micrometers.