Single-Ventricle Lesions

Children with complex congenital heart disease and hypoplasia of either ventricle frequently receive a bidirectional superior cavopulmonary shunt as a palliative procedure in anticipation of further surgical operations to reinstate all systemic venous return directly to the pulmonary artery. Thus, pulmonary blood flow occurs passively through the lungs in the absence of a subpulmonary ventricle. The pulmonary vascular resistance may influence both pulmonary blood flow and adequate systemic ventricular preload. Following such a superior cavopulmonary shunt intense cyanosis may occur 

In one patient respiratory syncytial virus pneumonia complicated his postoperative management. In contrast, this patient responded to inhaled nitric oxide with an increase in saturation from 48% to 87%, and the transpulmonary gradient decreased from 12 to 4 mm Hg without a change in left atrial pressure. He was subsequently managed for 93 hr on low-dose nitric oxide at doses of 3-10 ppm. Following resolution of his pneumonia, he made a good recovery. 

It is of interest that in all patients there was a rise in plasma cGMP levels in the superior vena cava and systemic arterial blood from 10 2 to 53 14 pmol/ml (P 0.05) following inhaled nitric oxide. This suggests that the nitric oxide was effectively delivered to the pulmonary vascular bed and that there was no impediment in the pulmonary guanylate cyclase pathway that impaired response. 

The lack of response in the other patients suggests that pulmonary vasoconstriction is not the cause of the desaturation and that perhaps other factors, such as cerebral blood flow requirements, have a significant effect on pulmonary blood flow (superior vena cava flow) in these patients. We have delivered nitric oxide to two patients following the total cavopulmonary anastomosis (Fontan), with an elevated transpulmonary gradient in the presence of left atrial hypertension due to a restrictive atrial septal defect in one patient and pulmonary venous obstruction by the Fontan baffle in another. Inhaled nitric oxide produced a reliable decrease in transpulmonary gradient in both, with an increase in saturation in one (with a fenestrated 

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