hello dear, your brother is having a complex cyanotic congenital heart disease with probably single ventricular physiology and reduced pulmonary blood flow. This usually needs multiple surgeries and single ventricle repair in which the single functional ventricle is made systemic and the veinous flow is diverted directly to Pulmonary arteries. That s why he underwent BT shunt for optimising pulmonary blood flow. And then BDG as a first stage of Fontan s repair in which the SVC is connected to Pulmonary artery. Now usually this is followed by another surgery in which the IVC is also connected with the Pulmonary artery and this is generally done at the age of 10-12 years. But in your brother s case, this is not done. May be because the unbalancing of the ventricles was not that severe and one of the ventricles was able to handle at least half of the veinous flow. This is called as hemi-Fontan surgery. Please show your brother to a paediatric Cardiologist and get a detailed echo to see the functioning of BDG shunt and also the native ventricles and valves. Now because he underwent BDG, he needs to be on oral anticoagulation in the form of acitrom. Hope this would help you.