Covered endoprosthesis with improved branch access

1 . An endoprosthesis, comprising:

an expandable framework including an anchoring portion and a body portion extending axially from the anchoring portion, wherein the body portion includes a plurality of body filaments interwoven around a central longitudinal axis of the expandable framework to define a plurality of body cells; and

a polymeric cover disposed on at least a portion of the expandable framework;

wherein the anchoring portion includes a first transverse flange disposed at a proximal end of the expandable framework and a second transverse flange disposed proximate the first transverse flange, the second transverse flange located distal of the first transverse flange, the first and the second transverse flanges being configured to secure the anchoring portion within an orifice of a body lumen;

wherein the body portion extends distally from the second transverse flange toward a distal end of the expandable framework, the body portion including a window through a side of the body portion distal of the second transverse flange, the window occupying space equivalent to at least two of the plurality of body cells;

wherein the window is formed by removing at least a portion of the plurality of body filaments leaving ends of the plurality of body filaments at a perimeter of the window;

wherein the perimeter of the window is at least partially defined by a plurality of welds joining the ends of the plurality of body filaments together along the perimeter;

wherein the window is devoid of the polymeric cover and any other structure within the perimeter of the window.

2 . The endoprosthesis of claim 1 , wherein the window is positioned adjacent the anchoring portion.

3 . The endoprosthesis of claim 1 , wherein the body portion is configured to dilate the body lumen.

4 . The endoprosthesis of claim 3 , wherein a first body portion opposite the window relative to the central longitudinal axis of the expandable framework is configured to exert less radially outward force on the body lumen than a second body portion opposite the anchoring portion relative to the window.

5 . The endoprosthesis of claim 1 , wherein the anchoring portion includes a saddle portion extending axially from the first transverse flange to the second transverse flange.

6 . The endoprosthesis of claim 5 , wherein the first transverse flange is configured to be positioned downstream of the orifice of the body lumen, the second transverse flange is configured to be positioned upstream of the orifice of the body lumen, and the saddle portion is configured to extend through the orifice of the body lumen.

7 . The endoprosthesis of claim 1 , wherein the anchoring portion includes a plurality of anchoring filaments interwoven around the central longitudinal axis of the expandable framework to define a plurality of anchoring cells.

8 . The endoprosthesis of claim 7 , wherein the plurality of anchoring cells is smaller than the plurality of body cells.

9 . The endoprosthesis of claim 7 , wherein the plurality of anchoring filaments is arranged in a first density and the plurality of body filaments is arranged in a second density, the first density being greater than the second density.

10 . The endoprosthesis of claim 1 , wherein the anchoring portion and the body portion are integrally formed as a monolithic structure.

11 . The endoprosthesis of claim 1 , wherein the window has a circumferential opening dimension of about 40% to about 60% of an overall circumference of the body portion.

12 . An endoprosthesis comprising:

an expandable framework formed of a plurality of interwoven filaments, the expandable framework including an anchoring portion at a first end of the expandable framework, and a body portion extending axially from the anchoring portion to a second end of the expandable framework, the body portion defining a first outer diameter and having a plurality of body cells; and

a polymeric cover disposed on at least a portion of the expandable framework;

wherein the anchoring portion includes a first transverse flange and a second transverse flange proximate the first transverse flange, the first and the second transverse flanges each have a second outer diameter larger than the first diameter and being configured to secure the anchoring portion within a body lumen;

wherein the body portion includes a window through a side of the body portion, the window occupying space equivalent to at least two of the plurality of body cells; and

wherein the window is devoid of the polymeric cover and any other structure within a perimeter of the window.

13 . The endoprosthesis of claim 12 , wherein a perimeter of the window is at least partially defined by a plurality of welds joining the plurality of filaments together along the perimeter of the window.

14 . The endoprosthesis of claim 12 , wherein the anchoring portion includes a saddle portion extending axially from the first transverse flange to the second transverse flange.

15 . The endoprosthesis of claim 12 , wherein the window has a circumferential opening dimension of about 40% to about 60% of an overall circumference of the body portion.

16 . The endoprosthesis of claim 12 , wherein the body portion has a uniform diameter from the anchoring portion to the second end.

17 . An endoprosthesis comprising:

an expandable framework including an anchoring portion, a body portion having a plurality of body cells, and a linking portion extending axially from the anchoring portion to the body portion; and

a polymeric cover disposed on at least a portion of the expandable framework;

wherein the linking portion includes a plurality of longitudinally-oriented struts spacing the body portion from the anchoring portion, the linking portion being devoid of the polymeric cover; and

wherein the expandable framework further includes a tapered flange extending axially between the anchoring portion and the body portion and extending radially outward from the linking portion.

18 . The endoprosthesis of claim 17 , wherein the anchoring portion includes a first transverse flange and a second transverse flange proximate the first transverse flange, the first and the second transverse flanges being configured to secure the anchoring portion at an orifice of a body lumen.

19 . The endoprosthesis of claim 17 , wherein the polymeric cover surrounds the body portion and the anchoring portion.