Covered endoprosthesis with improved branch drainage function

The endoprosthesis may include an expandable frame including a body portion disposed between a first end and a second end and a bowl portion disposed along the body portion; and a polymeric cover disposed on at least a portion of the expandable frame. The bowl may include an inner surface and an outer surface spaced radially outward from the inner surface. The bowl may extend radially outward from the body portion. The inner surface of the bowl may be free of a polymeric covering. 内假体可包括可扩张框架，该可扩张框架包括设置在第一端和第二端之间的主体部以及沿着主体部设置的碗状部；以及设置在可扩张框架的至少一部分上的聚合物覆盖物。碗状部可包括内表面和与内表面径向向外间隔开的外表面。碗状部可以从主体部径向向外延伸。碗状部的内表面可以没有聚合物覆盖物。