Advanced kink resistant stent graft
View Patent ↗Stent-grafts for treating thoracic aortic aneurysms and abdominal aortic aneurysms include graft portions having inflatable channels and graft extensions. The graft extensions include an undulating wire stent and porous, but substantially fluid impermeable, polytetrafluoroethylene (PTFE) graft materials.
1. An endovascular stent-graft comprising:
a tubular stent wall having opposed first and second ends;
an undulating wire having opposed first and second ends and being helically wound into a plurality of approximate circumferential windings to define said stent wall;
said undulating wire having a plurality undulations defined by peaks and valleys;
peaks of adjacently juxtaposed circumferential windings being separated by a distance (X) with said distance at said first end being different from said distance at said second end;
said first wire end secured to a first undulation at said first end;
said second wire end secured to a second undulation at said second end;
a graft liner comprising first plurality of layers of porous PTFE having no discernable node and fibril structure; and
a graft covering comprising a second plurality of layers of porous PTFE having no discernable node and fibril structure;
wherein said tubular stent wall is securably disposed between said graft covering and said graft lining;
wherein said endovascular stent-graft has a longitudinal axis and a radial axis perpendicular to said longitudinal axis; and wherein said undulating wire is helically wound at an acute winding angle of 3 degrees to 15 degrees with respect to said radial axis;
wherein said acute winding angle at a portion of said stent wall proximal to said first end of said stent wall is different from said acute winding angle at a portion of said stent wall proximal to said second end of said stent wall;
wherein said peaks and valleys of said undulating wire have a peak height (Y) from an apex of one peak to a base of an adjacently juxtaposed valley;
wherein a ratio of said distance between peaks of adjacently juxtaposed circumferential windings to the peak height (X/Y) is from −0.1 to 0.3 at said second end; and
wherein the graft liner and the graft covering has a combined thickness from 0.003 inches to 0.015 inches.
2. The endovascular stent-graft of claim 1 , wherein said peaks of one circumferential winding are substantially aligned with said peaks of an adjacently juxtaposed circumferential winding.
3. The endovascular stent-graft of claim 1 , wherein said peaks of one circumferential winding are substantially aligned with said valleys of an adjacently juxtaposed circumferential winding.
4. The endovascular stent-graft of claim 1 , wherein said acute winding angle at a portion of said stent wall proximal to said first end of said stent wall is different from said acute winding angle at a portion of said stent wall proximal to said second end of said stent wall.
5. The endovascular stent-graft of claim 1 , wherein a first winding at said first end is perpendicular to said longitudinal axis and wherein a terminal winding at said second end is perpendicular to said longitudinal axis.
6. The endovascular stent-graft of claim 1 , wherein, except for said first and said second wire ends being secured to said first and second undulations, respectively, adjacently juxtaposed circumferential windings are free of interconnecting struts and welds.
7. The endovascular stent-graft of claim 1 , wherein said graft liner and said graft covering is crimped between said peaks of adjacently juxtaposed circumferential windings to provide crimped graft portions.
8. The endovascular stent-graft of claim 7 , wherein said crimped graft portions are circumferential crimped portions.
9. The endovascular stent-graft of claim 1 , wherein said endovascular stent-graft wall has a diameter and wherein the peak height (Y) is from one fifth to one half of said diameter.