The ornamental design for a heart-shaped sleeve for a massage apparatus, as shown and described.
FIG. 1 is a perspective view of the heart-shaped sleeve for a massage apparatus, showing my design with the massage apparatus shown in phantom-line forming no part of the design;
FIG. 2 is a front view of the heart-shaped sleeve for a massage apparatus;
FIG. 3 is an opposing rear side view of the heart-shaped sleeve for a massage apparatus;
FIG. 4 is a left side view of the heart-shaped sleeve for a massage apparatus;
FIG. 5 is an opposing right side view of the heart-shaped sleeve for a massage apparatus;
FIG. 6 is a top view of the heart-shaped sleeve for a massage apparatus; and,
FIG. 7 is an opposing bottom view of the heart-shaped sleeve for a massage apparatus.