 Program looks at the human heart and circulatory system, with emphasis on 4 unusual cases and the medical treatments attempted to resolve them: A 6-year-old "blue baby"; a 16-year-old with a tangled growth of blood vessels around her spinal cord; a 41-year-old recipient of a coronary bypass; and a 61-year-old stroke victim suffering from a blockage of 2 arteries. The program begins with a look at the fetal development of the heart, including photography showing the beating heart of a weeks-old fetus.