What is the definition of patent ductus arteriosus?

Patent ductus arteriosus (PDA) is defined as a condition where the ductus arteriosus, a blood vessel that is essential during fetal development, fails to close after birth. This vessel connects the aorta and the pulmonary artery, allowing blood to bypass the lungs while the fetus is developing since the fetus receives oxygenated blood from the mother.

After birth, the closure of this duct is crucial, as the newborn begins to breathe air and the lungs take over the job of oxygenating the blood. If the ductus arteriosus remains open, or "patent," it can result in abnormal blood flow between the aorta and the pulmonary artery, leading to various complications, such as increased pressure in the pulmonary arteries and potentially heart failure over time.

The other choices describe different cardiovascular issues. The narrowing of arteries is typically associated with conditions such as atherosclerosis, which is not related to PDA. A blockage of blood flow can occur due to various reasons but is not specific to PDA. Lastly, an abnormal valve closure pertains to issues with the heart's valves and is distinct from the ductus arteriosus. Thus, the definition directly correlates with the characteristics and consequences of patent ductus arteriosus.