The Full form of PDA is Patent Ductus Arteriosus. In PDA, the word “patent” means open, it is a condition in which the ductus arteriosus does not close. Patent Ductus Arteriosus 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 and usually closes shortly after birth. If it remains open, however, it’s called a Patent Ductus Arteriosus. A small PDA often doesn’t cause problems and might never need treatment. However, a large PDA left untreated can allow poorly oxygenated blood flow in the wrong direction, weakening the heart muscle and causing heart failure and other complications. A large PDA found during infancy or childhood might cause poor eating, which leads to poor growth, sweating with eating or crying, persistent fast breathing or breathlessness, rapid heart rate or easy tiring. A person should immediately contact the doctor if his baby or older child isn’t gaining weight, tires easily when eating or playing, becomes breathless when crying or eating, always breathes rapidly or is short of breath.