A medical device, comprising: a stent-graft defining a first free end, a second free end, and an intermediate portion between the first and second free ends, the stent-graft having an undeployed state with an undeployed diameter and an undeployed longitudinal length between the first free end and the second free end and a deployed state with a deployed diameter and a deployed longitudinal length between the first free end and the second free end, the stent-graft including a stent portion and a graft portion; and a catheter assembly onto which the stent-graft is assembled in the undeployed state, the catheter assembly including, a balloon having a first balloon end and a second balloon end, and a cover concentrically surrounding the balloon, said cover having a first cover end, a second cover end and reinforcing portions, wherein the reinforcing portions of the cover are configured to resist inflation of corresponding first and second shoulder portions (290, 292) of the balloon so as to reduce longitudinal compression of the stent-graft as the balloon expands the stent-graft from its undeployed state to its deployed state, wherein the reinforcing portions of the cover include a segment that surrounds at least a portion of the first shoulder portion and a segment that surrounds at least a portion of the second shoulder portion, wherein the segments (284, 286) have an increased thickness relative to a thickness of a remainder of the cover, wherein the first cover end and the second cover end extend beyond the first balloon end and the second balloon end, and wherein the intermediate portion of the stent-graft imparts a resistance to expansion of the balloon at the intermediate portion of the stent-graft and wherein the cover also imparts a resistance to expansion of the balloon to reduce a difference in an expansion rate of the balloon at the free ends of the stent-graft relative to an expansion rate of the balloon at the intermediate portion of the stent-graft so as to reduce longitudinal compression of the stent-graft as the balloon expands the stent-graft from its undeployed state to its deployed state. a stent-graft defining a first free end, a second free end, and an intermediate portion between the first and second free ends, the stent-graft having an undeployed state with an undeployed diameter and an undeployed longitudinal length between the first free end and the second free end and a deployed state with a deployed diameter and a deployed longitudinal length between the first free end and the second free end, the stent-graft including a stent portion and a graft portion; and a catheter assembly onto which the stent-graft is assembled in the undeployed state, the catheter assembly including, a balloon having a first balloon end and a second balloon end, and a cover concentrically surrounding the balloon, said cover having a first cover end, a second cover end and reinforcing portions, wherein the reinforcing portions of the cover are configured to resist inflation of corresponding first and second shoulder portions (290, 292) of the balloon so as to reduce longitudinal compression of the stent-graft as the balloon expands the stent-graft from its undeployed state to its deployed state, wherein the reinforcing portions of the cover include a segment that surrounds at least a portion of the first shoulder portion and a segment that surrounds at least a portion of the second shoulder portion, wherein the segments (284, 286) have an increased thickness relative to a thickness of a remainder of the cover, wherein the first cover end and the second cover end extend beyond the first balloon end and the second balloon end, and wherein the intermediate portion of the stent-graft imparts a resistance to expansion of the balloon at the intermediate portion of the stent-graft and wherein the cover also imparts a resistance to expansion of the balloon to reduce a difference in an expansion rate of the balloon at the free ends of the stent-graft relative to an expansion rate of the balloon at the intermediate portion of the stent-graft so as to reduce longitudinal compression of the stent-graft as the balloon expands the stent-graft from its undeployed state to its deployed state.