Acute cyanosis following balloon angioplasty of residual arch obstruction after the Norwood I operation

: A 7-month-old child with residual aortic arch obstruction following a modified Norwood I operation developed profound cyanosis with subsequent bradycardia and hypotension immediately after successful balloon angioplasty. This complication of aortic angioplasty is specific to patients with this physiology. The pathophysiology of the event is discussed.