Prosthesis with branched portion

1. A prosthesis, comprising:

a tubular graft body including a sidewall extending between an inflow end and an outflow end and defining a main lumen between the outflow and inflow ends;

a stent structure coupled along the graft body;

a trough extending from the sidewall and comprising:

a first trough wall composed from a portion of the sidewall of the tubular graft body,

a first trough wall boundary bounding the first trough wall, the first trough wall including a first end, a second end longitudinally spaced from the first end, and first and second edges between the first and second ends, and

first and second opposed outer trough walls attached to the first trough wall along the first and second edges of the first trough wall boundary and extending outwardly from the first trough wall, and

a trough boundary;

and

a tubular branch defining a branch lumen and extending from the trough towards one of the inflow or outflow ends of the graft body, wherein the trough, the branch lumen, and the main lumen are in fluid communication, and wherein the first trough wall presents a continuous surface to the branch lumen.

2. The prosthesis of claim 1 , wherein the trough extends between adjacent struts of a stent of the stent structure.

3. The prosthesis of claim 2 , wherein the first and second opposed outer trough walls taper inwardly.

4. The prosthesis of claim 1 , wherein the stent structure comprises a series of stents each including a plurality of interconnected struts in an undulating pattern and at least a portion of the trough is disposed between a pair of interconnected struts.

5. The prosthesis of claim 1 , wherein the side branch and the first and second opposed outer trough walls are integrally formed from a single graft material piece.

6. The prosthesis of claim 1 , wherein the trough boundary includes a trough frame about at least a portion of a perimeter of the trough boundary.

7. The prosthesis of claim 6 , wherein the first and second opposed outer trough walls includes the trough frame.

8. The prosthesis of claim 1 , wherein the first trough wall comprises a tab cut into the sidewall having at least one edge that is unattached to the sidewall such that an opening is formed in the sidewall.

9. The prosthesis of claim 8 , wherein the first and second opposed outer trough walls are attached to the at least one edge.

10. The prosthesis of claim 9 , wherein the opening in the sidewall forms an open end of the branch lumen.

11. The prosthesis of claim 10 , wherein the opening is perpendicular to a longitudinal axis of the tubular graft body.

12. The prosthesis of claim 11 , wherein the opening opens to one of the inflow or outflow ends.

13. The prosthesis of claim 1 , wherein the first trough wall is oriented obliquely relative to a longitudinal axis of the tubular graft body.

14. A prosthesis, comprising:

a tubular graft body defining a main lumen extending between an inflow end and an outflow end of the graft body;

a stent structure coupled along the graft body;

a trough defined by a boundary formed at a sidewall of the graft body and extending away from the side wall, wherein a portion of the boundary provides an unobstructed transition surface between the trough and the sidewall; and

an internal branch defining a branch lumen and extending away from the trough towards one of the inflow or outflow ends of the graft body within the main lumen, wherein the trough, the branch lumen, and the main lumen are in fluid communication, and wherein the trough includes a branch lumen facing surface that is a continuous surface with an outer surface of the sidewall of the graft body and an inner surface of the branch lumen.

15. The prosthesis of claim 14 , wherein the stent structure comprises a plurality of stents, a first proximal stent of the plurality of stents being disposed approximate the inflow end of the graft body along an inner surface of the graft body, a second proximal stent being disposed distal to the first proximal stent by a spacing, wherein the second proximal stent includes a pair of interconnected struts, and at least a portion of the boundary is disposed between the pair of interconnected struts.