What is the embryological origin of a patent ductus arteriosus (PDA) in newborns?

A patent ductus arteriosus (PDA) originates from the sixth aortic arch during embryological development. The ductus arteriosus is a critical structure in fetal circulation that connects the pulmonary artery to the descending aorta, allowing blood to bypass the non-functioning lungs. In normal fetal development, the sixth aortic arch contributes to the formation of various pulmonary vessels, including the ductus arteriosus.

After birth, the ductus arteriosus typically closes within the first few days of life; if it remains patent, it can lead to excessive blood flow to the lungs and heart failure. Understanding its embryological origin helps clarify the development of cardiovascular anomalies in newborns.

In contrast, the first, second, and fourth aortic arches are involved in the formation of different structures in the developing embryo, such as parts of the aortic arch and branchial arteries, but are not directly related to the formation of the ductus arteriosus. Thus, recognizing the correct embryological source of a PDA underscores the importance of the sixth aortic arch in cardiovascular development.