Truncus arteriosus is an extremely rare and dangerous form of congenital heart disease that requires surgical repair, usually within the first three months of a baby’s life. It occurs during the early stages of pregnancy when the common truncus (which forms the arteries of the heart) fails to separate into the aorta and pulmonary artery. A baby with this condition will appear blue shortly after being born, and may have a detectable heart murmur. Because of the mixing of oxygenated and non-oxygenated blood that occurs with this condition, the heart has to work extra hard, and rapidly goes into heart failure (which means an inability to pump as much blood as is needed, not heart stoppage). This occurs over just a few weeks’ time and causes rapid breathing, poor feeding and an inability of the infant to gain weight.