Question

Which of the following statements about PDA is not true?

• A. PDA is located proximal to the left subclavian artery
• B. PDA connects the Pulmonary Artery to the descending aorta
• C. Small PDA’s are often asymptomatic
• D. Continuous murmur is a typical auscultatory finding.

Hint:

Anatomical hallmark: PDA connects the pulmonary artery to the descending aorta just distal to the left subclavian artery. Continuous Gibson murmur is best heard in the left infraclavicular region.

Answer 1

The Correct Option is A

Concept:
Patent ductus arteriosus (PDA) is a persistent vascular structure derived embryologically from the distal portion of the left sixth aortic arch.
In normal fetal circulation, the ductus arteriosus shunts deoxygenated blood away from high-resistance fetal pulmonary vasculature into the descending aorta.
Explanation:
• Anatomically, the ductus arteriosus originates from the bifurcation of the main pulmonary trunk (or origin of the left pulmonary artery) and inserts into the aortic isthmus distal to the origin of the left subclavian artery.

• Stating that the PDA is located proximal to the left subclavian artery is anatomically incorrect; preductal coarctation occurs proximal to it, but the PDA itself inserts distally.

• The PDA provides a direct connection between the pulmonary arterial tree and the descending thoracic aorta.

• Small ("restrictive") PDAs generate minimal left-to-right shunting, preserve normal pulmonary pressures, and are typically asymptomatic, often discovered incidentally during routine auscultation.

• The classic auscultatory finding of a hemodynamically significant PDA is a continuous "machinery" (Gibson) murmur, heard loudest in the left upper sternal border/infraclavicular area, spilling past the second heart sound ($S_2$) into diastole.
Final Answer:
The false statement is that the PDA is located proximal to the left subclavian artery; it anatomically inserts distal to the left subclavian artery.