A perfusion cannula constructed of a wire mesh or other structure having an expandable portion capable of expanding from a constricted state to an expanded state such that a vessel is stented open while permitting fluid flow through a cannula into the vessel. An insulating sheath layer is extruded about the core to encompass the shield element, and a multi-wire cable component having ribbonized ends and detached intermediate portions is connected to an end of the core. The zoom lens system includes a first optical unit located between the object and the first intermediate real image.