Addison Pervine, 19 months old, right, shows signs of fatigue at a nursery Bible class being taught by Kay Boyd, top, Wednesday night at Sutton Lane Church of Christ. Addi has a heart defect that causes her oxygenated blood to mix with un-oxygenated blood in her heart, making her tire more easily than other children. "Her oxygen (saturation) level stays at about 80 to 85%, which is too low for normal people to function, but her body is just used to working that way," said Addi's mother, Amy.