Interrupted aortic arch with retrograde subclavian perfusion.

Type B interrupted aortic arch results in the left subclavian artery being perfused by a patent ductus arteriosus and antegrade flow is usually seen in the left subclavian artery. We describe a case of retrograde perfusion of the left subclavian artery through the circle of Willis in the presence of interrupted aortic arch type B and a restrictive patent ductus arteriosus. This is similar to subclavian steal syndrome when the perfusion pressure from the cerebral circuit is greater than that from the left subclavian artery. Early recognition of this phenomenon may alter management by indicating restriction at ductal level. This case highlights the need for a comprehensive review of both ventricular systolic function and ductal haemodynamics when retrograde flow is seen in the subclavian artery.