You pre-compose the heart and animate it, then apply Motion Tile to the pre-comp layer in the parent comp. Basics.
If you apply Motion Tile to your animated layer then you should have no problems. If you apply Motion Tile to an adjustment layer then then everything below the heart will move. If you want to tile the heart on a blue background then, as Mylenium said, you need to pre-compose your heart and blue background layer, then apply Motion Tile to the nested comp.
I'd figure out how to make the heart pulse, render it, and reimport the movie of the pulsing heart. Then I'd build the rest of the project using the movie. If you later change your mind about the nature of the animated heart, redo it and replace the layer with the new movie.
Back in the olden days, AE could only render one effect to one layer at a time (or so it seemed). We learned how to do complex effects with precomps and multiple passes using prerenders. And that's how I approach every project still.
Thank you so much guys, it actually worked The onlything that doesn't seem to be working is the fast blur effect. It seems to effect the hearts and the solid background even when i put it in the precompose layer