Hyperfunction of Blalock anastomosis associated with Marfan's syndrome.

Hyperfunction of the subclavian-pulmonary artery anastomosis causing pulmonary vascular disease is uncommon. The mechanism for the late development of an overgenerous shunt is usually obscure. We report the case of a 31-year-old patient with Fallot's tetralogy and Marfan's syndrome who had undergone a right Blalock manoeuvre at the age of 5. At necropsy the Blalock anastomosis was widely patent and the changes of plexogenic pulmonary arteriopathy were noted. The association of Marfan's syndrome offers an explanation for the continued growth of the subclavian-pulmonary artery connection and subsequent pulmonary vascular changes.