Case report Portal-systemic encephalopathy after Fontan-type operation in patient with polysplenia syndrome

An 18-year-old patient, who had polysplenia and single ventricle, presented with altered mental status 9 years after a Fontan-type operation and pacemaker implantation. Heunderwentreplacement of commonatrioventricular valveand aorticvalve plasty1 year previouslyand has been placed on multiple medications includingbeta-blocker for his poor ventricular function. Blood chemistry revealed hyperammonemia of 2420 mg/l as a cause ofthis alteredmentalstatusdisturbance.Superiormesentericarteriographyrevealedlarge portal-systemic shunts invenous phaseas a cause of hyperammonemia. To control blood ammonia level, we placed him on low protein diet, oral polymixin B, and lactulose instead of closing shunt with device. This case illustrates that portal-systemic shunt may result in hyperammonemia leading to altered mental status long after a Fontan-type operation. # 2009 European Association for Cardio-Thoracic Surgery. Published by Elsevier B.V. All rights reserved.