Depending on recipe and cooking method it may be either a flaky potato pie, or a heavy potato pudding.
Ductus arteriosus: A short vessel through which blood headed from the heart via the pulmonary artery to the lungs is shunted before birth. This blood is shunted away from the lungs and returned to the aorta. When the shunt is open, it is said to be patent.
But when the ductus fails to close, a condition called patent (meaning open) ductus arteriosus (PDA) results, in which oxygen-rich blood from the aorta is allowed to mix with oxygen-poor blood in the pulmonary artery.