Late-onset Blalock-Taussig shunt occlusion due to a subclavian artery pseudoaneurysm.

A 3-month-old infant with tetralogy of Fallot presented with progressive severe cyanosis and intractable acidosis about 2 months after a successful modified right-sided Blalock-Taussig shunt. At cardiac catheterization, the suspected shunt malfunction was confirmed. It was due to a bulky, pear-like mass arising from the right subclavian artery and compressing the polytetrafluoroethylene conduit. Any attempt to recanalize the shunt by percutaneous techniques proved unsuccessful. At surgery, a huge dilation of the anterior wall of the right subclavian artery, that sharply bent the prosthetic conduit, was found. Pathologic examination revealed that the compressing mass was pseudo-aneurysmal in nature. Despite a second successful shunt operation with a dramatic clinical improvement, the patient died due to multiorgan failure 72 hours following surgery. Extrinsic compression by a false aneurysm is a rare cause of shunt occlusion that should always be suspected in patients presenting with a rapidly progressive shunt malfunction late after a successful shunt procedure.