patent (persistent) ductus arteriosus
This 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.
If it´s small, it often doesn´t cause problems and needs no treatment. Large ones do (medication, surgery).