A modular endograft system, comprising: a first endograft device having a first superior portion (108, 208), the first superior portion having a convexly curved first outer wall (112, 212) and a first septal wall (114, 214) that define a substantially D-shaped cross-section, a first inferior portion having a smaller cross-sectional dimension than the first superior portion (108, 208), a first lumen through the first superior and first inferior portions; and a second endograft device having a second superior portion (108, 208), the second superior portion having a convexly curved second outer wall (112, 212) and a second septal wall (114, 214) that define a substantially D-shaped cross-section, a second inferior portion having a smaller cross-sectional dimension than the second superior portion (108, 208), a second lumen through the second superior and second inferior portions; and wherein the first and second endograft devices (102a, 102b) are configured to self-expand into an expanded configuration via inherent hoop force of the first and second endograft devices such that the first and second septal walls (114, 214) press against each other and form a septum (120, 220) between the first and second lumens; and characterized in that the first endograft device has a first braided frame and a first cover attached to the first braided frame, the first cover having a first inferior terminus and a first superior terminus, and the first braided frame having a first end extending distally beyond the first superior terminus of the first cover and second end extending proximally beyond the first inferior terminus of the first cover; and the second endograft device has a second braided frame and a second cover attached to the second braided frame, the second cover having a second inferior terminus and a second superior terminus, and the second braided frame having a first end extending distally beyond the second superior terminus of the second cover and a second end extending proximally beyond the second inferior terminus of the second cover. a first endograft device having a first superior portion (108, 208), the first superior portion having a convexly curved first outer wall (112, 212) and a first septal wall (114, 214) that define a substantially D-shaped cross-section, a first inferior portion having a smaller cross-sectional dimension than the first superior portion (108, 208), a first lumen through the first superior and first inferior portions; and a first superior portion (108, 208), the first superior portion having a convexly curved first outer wall (112, 212) and a first septal wall (114, 214) that define a substantially D-shaped cross-section, a first inferior portion having a smaller cross-sectional dimension than the first superior portion (108, 208), a first lumen through the first superior and first inferior portions; and a second endograft device having a second superior portion (108, 208), the second superior portion having a convexly curved second outer wall (112, 212) and a second septal wall (114, 214) that define a substantially D-shaped cross-section, a second inferior portion having a smaller cross-sectional dimension than the second superior portion (108, 208), a second lumen through the second superior and second inferior portions; and a second superior portion (108, 208), the second superior portion having a convexly curved second outer wall (112, 212) and a second septal wall (114, 214) that define a substantially D-shaped cross-section, a second inferior portion having a smaller cross-sectional dimension than the second superior portion (108, 208), a second lumen through the second superior and second inferior portions; and wherein the first and second endograft devices (102a, 102b) are configured to self-expand into an expanded configuration via inherent hoop force of the first and second endograft devices such that the first and second septal walls (114, 214) press against each other and form a septum (120, 220) between the first and second lumens; and characterized in that the first endograft device has a first braided frame and a first cover attached to the first braided frame, the first cover having a first inferior terminus and a first superior terminus, and the first braided frame having a first end extending distally beyond the first superior terminus of the first cover and second end extending proximally beyond the first inferior terminus of the first cover; and the second endograft device has a second braided frame and a second cover attached to the second braided frame, the second cover having a second inferior terminus and a second superior terminus, and the second braided frame having a first end extending distally beyond the second superior terminus of the second cover and a second end extending proximally beyond the second inferior terminus of the second cover.