An infant with severe respiratory distress is found to have double aoic arch during investigation. Double aoic arch is due to persistence and continued patency of the segment of:
**Core Concept**
The **double aortic arch** is a rare congenital anomaly of the aortic arch that results from the persistence of a structure that normally regresses during embryonic development. This condition is characterized by the presence of two aortic arches, one arising from the ascending aorta and encircling the trachea and esophagus, which can lead to respiratory and swallowing difficulties. The embryological development of the aortic arches involves the formation and regression of several structures.
**Why the Correct Answer is Right**
The correct answer involves understanding the embryological development of the aortic arches. Normally, the distal portion of the right dorsal aortic root regresses, while the left dorsal aortic root persists. In the case of a double aortic arch, the **right dorsal aortic root** fails to regress, leading to the formation of two aortic arches. This persistence and continued patency of the segment that should have regressed result in the double aortic arch anomaly.
**Why Each Wrong Option is Incorrect**
**Option A:** This choice is incorrect because it does not accurately describe the embryological origin of the double aortic arch.
**Option B:** Similarly, this option is incorrect as it does not represent the correct segment involved in the formation of a double aortic arch.
**Option D:** This option is also incorrect as it refers to a different aspect of aortic arch development.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that double aortic arch is a cause of **stridor** and **dysphagia** in infants due to the encirclement and compression of the trachea and esophagus by the two aortic arches. Recognizing this condition is crucial for timely surgical intervention to relieve these symptoms.
**Correct Answer:** D. distal portion of the right dorsal aortic root