Congenital heart defects arise from problems early in the heart's development — but there's often no clear cause. Genetics and environmental factors might play a role.

Before birth, a vascular connection (ductus arteriosus) between two major blood vessels leading from the heart — the aorta and pulmonary artery — is necessary for your baby's blood circulation. The ductus arteriosus diverts blood from your baby's lungs while they develop and the baby receives oxygen from the mother's circulation.

After birth, the ductus arteriosus normally closes within two or three days. In premature infants, the connection often takes longer to close. If the connection remains open, it's referred to as a patent ductus arteriosus.

The abnormal opening causes too much blood to circulate to the baby's lungs and heart. Untreated, the blood pressure in the baby's lungs might increase (pulmonary hypertension) and the baby's heart might enlarge and weaken.

Dec. 16, 2014

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