A medical device delivery system includes a self-expanding medical device mounted on a balloon portion of a catheter. A sheath is provided around the medical device to hold the device in place with the device staying in a compressed state. The balloon portion is inflated to cause the sheath to rupture and release the self-expanding medical device. A number of radio-opaque markers in a pattern that will aid in determining whether or not the sheath has properly ruptured upon inflation of the balloon portion are provided on the sheath. The radio-opaque markers are positioned with respect to an expected sheath rupture propagation path along which the sheath is expected to rupture. The pattern of the markers changes as the sheath ruptures and this change is detected by an operator of the system.