Hello, The most likely reason for the Coarctation of Aorta is congenital defect of the heart and output channels most likely during early embryologic development phase of the fetus. The extent of defect in your child needs evaluation with all the details of angiography, 2 D echo and relevant investigations. Kindly upload all the available documents as scanned copies in the follow up conversation for my analysis and then I can predict some sort of further guidance for you. So far as failure of angioplasty is concerned, there may be various reasons and it is quite acceptable in such congenital defect cases where adequate tissue strength is not available since beginning. Wish your toddler the best of health and recovery. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Bhagyesh V. Patel, General Surgeon