Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Patent Ductus Arteriosus ?
    ### Response:
    Patent ductus arteriosus (PDA) is a heart problem that occurs soon after birth in some babies. In PDA, abnormal blood flow occurs between two of the major arteries connected to the heart.
                
Before birth, the two major arteriesthe aorta and the pulmonary (PULL-mun-ary) arteryare connected by a blood vessel called the ductus arteriosus.
    