A medical device for temporarily provide sealing off a communication between a high flow main lumen of a body into an opening in a wall of said main lumen at a site inside said body, said medical device comprises a delivery system, wherein said medical device is and remains proximally affixed to said delivery system and is collapsible and expandable for transluminal delivery to and from said site , and comprises an aggregate of: a) a first inflatable balloon having a longitudinal dimension that extends substantially between a proximal end and a distal end thereof, a radially inner wall and a radially outer wall at a radial distance therebetween when said first balloon is in an inflated state in which said balloon at said inner wall has a natural inner inflated diameter and surrounds an inner hollow for providing a longitudinal fluid flow passage through said inner hollow along said main lumen and past said opening , and when in said inflated state said outer wall of said first balloon is in at least partly apposition to said wall of said main lumen at said site ; and b) at least one collapsible and expandable support structure having an expanded diameter, longitudinally arranged from said proximal end and to within said distal end of said first balloon , and radially arranged at said inner wall , whereby said support structure, when in an expanded state, supports a patency of said inner hollow of said first balloon at least in said inflated state thereof; characterized in that said expanded diameter is larger than said inner inflated diameter, and said radial distance is substantially smaller than said inner inflated diameter; in such a manner that said device substantially keeps a passage of said fluid through said main lumen open and to sealingly shuts off communication through said opening when said device is deployed at said site and said medical device not comprising an agent delivery port for delivery of an agent into said opening ; and comprising a second balloon , wherein said support structure is balloon expandable by said second balloon that expands said tubular support to said expanded diameter and at least partly arranged inside said inner of said first balloon, wherein said second balloon is longitudinally at least extending between said proximal end and distal end of said support structure . a) a first inflatable balloon having a longitudinal dimension that extends substantially between a proximal end and a distal end thereof, a radially inner wall and a radially outer wall at a radial distance therebetween when said first balloon is in an inflated state in which said balloon at said inner wall has a natural inner inflated diameter and surrounds an inner hollow for providing a longitudinal fluid flow passage through said inner hollow along said main lumen and past said opening , and when in said inflated state said outer wall of said first balloon is in at least partly apposition to said wall of said main lumen at said site ; and b) at least one collapsible and expandable support structure having an expanded diameter, longitudinally arranged from said proximal end and to within said distal end of said first balloon , and radially arranged at said inner wall , whereby said support structure, when in an expanded state, supports a patency of said inner hollow of said first balloon at least in said inflated state thereof; <EOS>