Cardiovascular simulation study of infants with transposition of the great arteries after surgical correction

After the Mustard operation in infants for transposition of the great arteries (TGA), unusually contoured pressure waveforms are observed. We studied this phenomenon by devising a pressure-flow model of the infant circulation into which was incorporated a model of the Mustard operation. This latter model dealt in particular with pressure coupling across the initially flexible baffle material used to repartition the atria and also with the changes in coupling which occur as the baffle material stiffens. The models were implemented on a hybrid computer system. A reasonable approximation to the unusual waveforms observed clinically was found during simulation experiments. The model has given us new insight into the physiological consequences of the Mustard operation and has yielded a reasonable hypothesis for explaining the clinical observations.