Aortopulmonary Window (AP Window)

• Aortopulmonary Fenestration.
• Aortopulomary Fistula.
• Aortic Septal Defect.
• Large communication between descending aorta and MPA.
• There must be two distinct and separate semilunar valves.
• Opening is wide and lies close to RPA.
• Usually L-R shunt. 

Embryology of AP Window

• Failure of aortopulmonary septation.
• 50% have no associated defects: PDA, Coarctation of AO, VSD, Interupted AO Arch, TOF.

   

Types of AP Windows

• Type I: small defect midway between the semilunar valves and the pulmonary artery bifurcation (most common).
• Type II: distal defect whose border is formed by the pulmonary artery bifurcation; associated with aortic origin of right pulmonary artery.
• Type III: large defect, includes both type I and II (rare). 

Hemodynamics of AP Windows

• Small shunts: asymptomatic (infrequent).
• Moderate to large shunt: CHF, Failure to Thrive, Tachypnea, Recurrent Respiratory Infection and PHTN.
• AP windows will eventually result in increased pulmonary blood flow, right sided volume overload and PHTN.

   

   

AP Windows by Echo

• 2D: Best view is PSAX.
• Will see T sign in area of defect to help eliminate calling it "drop out".
• Increased flow in pulmonary circulation will lead to dilation of LA, LV, and PVeins.
• Doppler:Continuous flow across the defect.
• Turbulent flow across defect.
• Retrograde flow in the descending abdominal aorta (like PDA).

Intervention and Treatment of AP Windows

• Intervention should happen as soon as possible.
• Surgical repair: closing the defect with a synthetic patch or small piece of pericardium.