Disclosed herein are medical devices comprising a single-lobed, thin-walled, expandable body ("ballstent" or "blockstent") and a flexible, elongated delivery device ("delivery catheter") and systems and methods of use for treating saccular vascular aneurysms and methods of use for occluding segments of blood vessels and other biological conduits. Expandable bodies comprising gold, platinum, or silver that can be compressed, positioned in the lumen of an aneurysm or blood vessel, and expanded to conform to the shape of the aneurysm or segment of blood vessel or biological conduit are disclosed. The external surface of the expandable bodies can be configured to promote local thrombosis and to promote the growth of tissue into and around the wall in order to reduce migration of the expandable body and to occlude and seal the aneurysm or biological conduit. The wall of the expandable bodies can also be configured to release drugs or pharmacologically active molecules, such as those that promote thrombosis, cell proliferation, extracellular matrix deposition, or tissue ingrowth.
