“Truncus arteriosus is a rare heart defect that’s present at birth (congenital).   It means that one large blood vessel leads out of the heart. Normally, there are two separate vessels coming out of the heart.  Patent ductus arteriosus (PDA) is a persistent opening between the two major blood vessels leading from the heart. The opening, called the ductus arteriosus, is a normal part of a baby’s circulatory system before birth that usually closes shortly after birth. If it remains open, however, it’s called a patent ductus arteriosus.  Patent ductus arteriosus (PDA) is a persistent opening between the two major blood vessels leading from the heart. The opening, called the ductus arteriosus, is a normal part of a baby’s circulatory system before birth that usually closes shortly after birth. If it remains open, however, it’s called a patent ductus arteriosus.”

MAYO CLINIC