Assembly of stent grafts with diameter reducing ties
A temporary diameter reduction constraint arrangement for a stent graft is disclosed. The arrangement comprises: primary and secondary release wires extending along the graft; a plurality of loops of thread, each loop engaged with either the primary or secondary wire and engaged around a portion of the graft circumferentially spaced away from its release wire, and drawn tight to reduce the diameter of the graft; an end constraint arrangement comprising four of the plurality of loops of thread arranged into a first and second pairs engaged with respective primary and secondary wires; and an intermediate constraint arrangement comprising a fifth and sixth of the plurality of loops of thread arranged into a third pair, the third pair engaged with the primary release wire, the primary release wire deviating towards the secondary release wire so as to locate the intermediate constraint arrangement substantially in-line with the end constraint arrangement.
1. A temporary diameter reduction constraint arrangement for a stent graft in combination with a stent graft, the stent graft having a proximal end and a distal end and comprising a biocompatible graft material tube and a plurality of longitudinally spaced apart self-expanding stents fastened thereto, including at least an end stent and a plurality of intermediate stents, the constraint arrangement comprising:
a primary release wire extending longitudinally along the graft material tube;
a secondary release wire extending longitudinally along the graft material tube and deviating towards the primary release wire;
a plurality of loops of thread, each loop engaged with one or other of the primary and secondary release wires and engaged around a portion of the stent graft circumferentially spaced a selected distance away from its release wire, and drawn tight and tied to itself to reduce the stent graft;
an end constraint arrangement comprising four of the plurality of loops of thread arranged into a first pair and second pair, the first pair engaged with the primary release wire and the second pair engaged with the secondary release wire;
a plurality of intermediate constraint arrangements, one of the intermediate constraint arrangements comprising a fifth and sixth of the plurality of loops of thread arranged into a third pair, the third pair engaged with the primary release wire, the primary release wire deviating towards the secondary release wire; and
each constraint arrangement comprising pairs of loops of thread engaged with the primary release wire.
2. The temporary diameter reduction constraint arrangement as claimed in claim 1 wherein the primary release wire deviates towards the secondary release wire.
3. The temporary diameter reduction constraint arrangement as claimed in claim 2 wherein the deviation of the primary and secondary release wires toward each other is symmetrical.
4. The temporary diameter reduction constraint arrangement as claimed in claim 1 wherein the end constraint arrangement constrains a sealing stent at the proximal end of the stent graft.
5. The temporary diameter reduction constraint arrangement as claimed in claim 4 comprising a distal end constraint arrangement, the distal end constraint arrangement substantially in-line with the intermediate constraint arrangement.
6. The temporary diameter reduction constraint arrangement as claimed in claim 5 wherein the stents are zig-zag stents comprising struts and bends there-between and each loop of thread engages around a strut.
7. The temporary diameter reduction constraint arrangement as claimed in claim 6 wherein the end stent is non-super elastic.
8. The temporary diameter reduction constraint arrangement as claimed in claim 6 wherein the intermediate stents are super elastic.
9. An expandible stent graft having a proximal end and a distal end, the stent graft comprising a biocompatible graft material tube having a sealing zone at the proximal end and a plurality of longitudinally spaced apart self-expanding stents, including at least an end stent and a plurality of intermediate stents, the end stent attached to an internal wall of the graft material tube, the stent graft including a constraint arrangement comprising:
a primary release wire extending longitudinally along the graft material tube;
a secondary release wire extending longitudinally along the graft material tube;
a plurality of loops of thread, each loop engaged with one or other of the primary and secondary release wires and engaged around a portion of the stent graft circumferentially spaced a selected distance away from its release wire, and drawn tight and tied to itself to reduce the stent graft;
an end constraint arrangement comprising four of the plurality of loops of thread arranged into a first pair and second pair, the first pair engaged with the primary release wire and the second pair engaged with the secondary release wire; and
an intermediate constraint arrangement comprising a fifth and sixth of the plurality of loops of thread arranged into a third pair, the third pair engaged with the primary release wire, the primary release wire deviating towards the secondary release wire.
10. The stent graft as claimed in claim 9 comprising a plurality of intermediate constraint arrangements, each constraint arrangement comprising pairs of loops of thread engaged with the primary release wire.
11. The stent graft as claimed in claim 10 wherein the secondary release wire deviates towards the primary release wire.
12. The stent graft as claimed in claim 11 wherein the primary release wire deviates towards the secondary release wire.
13. The stent graft as claimed in claim 12 wherein the deviation of the primary and secondary release wires toward each other is symmetrical.
14. The stent graft as claimed in claim 13 comprising a distal end constraint arrangement, the distal end constraint arrangement substantially in-line with the intermediate constraint arrangement.
15. The stent graft as in claim 14 wherein the stents are zig-zag stents comprising struts and bends there-between and each loop of thread engages around a strut.