MRCP UK EXAMINATIONS

Detailed explanation-1: -Patent Ductus Arteriosus-The ductus arteriosus arises from the dorsal left sixth aortic arch and connects the pulmonary artery to the aorta. This connection is an important aspect of fetal circulation, allowing oxygenated blood to bypass the fluid-filled lungs that do not participate in gas exchange.

Detailed explanation-2: -Sixth aortic arch: Either of the sixth aortic arches divides into ventral and dorsal segments, and therefore, their derivatives also divide into these two segments. Right Sixth Arch: Ventral: Gives rise to the right pulmonary artery. Dorsal: It degenerates completely and loses its connection with the dorsal aorta.

Detailed explanation-3: -The left arch of the sixth pair contributes to the formation of the main and left pulmonary arteries and ductus arteriosus; this duct obliterates a few days after birth. The right sixth arch contributes to formation of the right pulmonary artery.