According to the hospital: "The actual defect in baby Vanellope's chest wall was quite small. The main concern with repositioning her heart was that the arteries and veins which bring blood to and from the heart were extremely elongated, and might become kinked and blocked when the heart was placed inside the chest wall. To ensure this didn't happen, the plan was to use a special splint to support the edges of the larger hole that had been created in the front of her chest, attached to its own plastic tube. This meant it was possible to hang her heart outside of her chest to help create more space within, and allow a plastic sheet to be stitched around it to seal the heart away from the outside air."