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Dictionary: Patent Ductus Arteriosus (PDA)

Patent ductus arteriosus (PDA): The ductus arteriosus is a blood vessel in the heart that connects the aorta to the pulmonary artery in an unborn baby. It usually closes soon after birth. If it doesn't close, it's called a patent (open) ductus arteriosus. A PDA can cause too much blood to flow to a baby's lungs.

Illustration: Patent Ductus Arteriosus