Do asymptomatic school children have normal haemodynamics 6-13 years after Mustard's operation?

Twenty asymptomatic school children who had undergone Mustard's operation for simple complete transposition (concordant atrioventricular and discordant ventriculo-arterial connexions) were catheterised electively 6-13 years later. The studies were carried out under general anaesthesia in air and in 100% O2. Oxygen consumption was measured and end-tidal gases were monitored using respiratory mass spectrometry. There was significant left ventricular outflow tract obstruction in 2 patients. Cardiac output in air was normal in 15 and decreased in 5 patients. The pulmonary vascular resistance was normal in 18 of 19 cases, but grossly elevated in one patient. Baffle dysfunction was present in 11 patients: 10 with important gradients between the venous pathways and the systemic venous atrium, and 5 with a leak identified either by a left-to-right shunt or by the course of the catheter. Balloon dilatation was attempted in the inferior caval venous channel in 6 and in the superior caval venous channel in 2. Mean gradient before the dilatation fell after the procedure. No pulmonary venous obstruction was identified. Even in this group of children selected as asymptomatic, approximately half had a detectable haemodynamic abnormality.