Actually, to do heart/lung transplants, you do not do a transplant fellowship. A transplant fellowship involves liver/kidney/pancreas or some combination thereof. A very few centers also do small bowel transplants. To do heart/lung transplants, you do a CT fellowship at a program with a high volume of heart/lung transplants. I have heard of surgeons doing 2 fellowships, but it's often not necessary. One of our pediatric transplant surgeons did a pediatric surgery fellowship, followed by a transplant fellowship. He's an amazing surgeon, and does pediatric liver/kidneys. He told me that both fellowships are not required to call yourself a pediatric transplant surgeon, however.