A heart support system featuring a sleeve sized to fit about at least a portion of an adult human heart in a living body, the sleeve having an inner surface arranged to contact the heart in use and a sheath extending about and constraining the sleeve. At least one of the sheath and sleeve carry a discrete mark detectable from outside the body with the sheath and sleeve implanted within the body. The position of the support system about the heart can be determined with reference to the mark.
