A catheter includes a longitudinally extending body having proximal and distal ends and defining at least one lumen that extends longitudinally from the proximal end through the body to the distal end and looping back to the proximal end. A liquid metal, e.g. an alloy of gallium and indium, such as galistan, is disposed in the lumen. In another aspect, a catheter includes a longitudinally extending body defining first and second lumens. An electrically driven device is coupled to a distal end of the body and is in electrical communication with the first and second lumens. A power source is in electrical communication with the first and second lumens and a liquid metal is disposed in the first and second lumens to provide an electrical conduit between the power source and electrically driven device. Each lumen may loop from a proximal end of the body to the distal end back to the proximal end.