Pulmonary Artery Size and Function After Fontan Operation at a Young Age

Purpose: To assess pulmonary artery (PA) size, flow variables, and wall shear stress (WSS) in patients after Fontan operation at a young age. Materials and Methods: Flow in the branch PA was obtained with phase contrast velocity-encoded cardiovascular magnetic resonance imaging in 14 patients before and after low-dose dobutamine stress (7.5 mu g/kg/min) and in 17 healthy controls at rest. Results: At rest, stroke index, total flow, average, and peak flow rate were all statistically significantly lower in patients than in controls [P < 0.001). With stress-testing, all variables increased in patients (P < 0.001), apart from stroke index, which did not change. At rest, branch PA area did not differ between patients and controls. Distensibility was lower in patients than in controls (P < 0.001). With stress-testing. area and distensibility did not change. At rest, WSS was lower in patients than in controls (P < 0.001). WSS increased with stress-testing (P < 0.001), but not to the same levels as during resting conditions of the control group. Conclusion: PA size is normal long-term after Fontan operation at a young age. Flow variables, distensibility, and WSS are significantly lower compared to healthy controls, and do not show adequate reactions with stress-testing, which is suggestive of pulmonary artery endothelial and/or vascular dysfunction.