Pulmonary vascular structure in patients dying after a Fontan procedure. The lung as a risk factor.

Pulmonary vascular structure was analysed in the lungs of 12 patients who had had a Fontan repair, 11 of whom died. Of the eight patients with a low pulmonary blood flow preoperatively, pulmonary vascular structure was almost normal in seven, but in the remaining patient many intra-acinar arteries contained organised occlusive thrombi. Of the four patients with an increased pulmonary blood flow immediately before operation, there was a significant increase in pulmonary vascular smooth muscle despite three of the patients having had a pulmonary arterial band. The findings suggest that it is more difficult for patients with an increased pulmonary blood flow to fulfil the Fontan criteria for repair, and even when the pulmonary vascular resistance is less than 4 units/m2 there may be significant pulmonary vascular abnormalities likely to increase right atrial afterload and prejudice the outcome of a Fontan repair.