Optimal conduit size for extracardiac Fontan operation

Background: Lack of conduit growth potential and thrombogenicity are the main drawbacks of the extracardiac Fontan operation (ECFO). Optimal size of the conduit according to the patients age and inferior vena cava diameter has not been established. Objectives: We set out to ascertain whether the optimal dimensions of the conduit could be determined before an ECFO. Methods: Actual and expected age-related inferior vena cava diameters were compared with the extracardiac conduit diameter in 20 patients after ECFO. In 50 other pediatric and adult patients, the distance between intrapericardial part of the inferior vena cava and the undersurface of the right pulmonary artery (IVC–RPA) was measured. Cases of conduit thrombosis were analyzed. Results: The actual diameter of the inferior vena cava was variable and has a weak correlation with anthropmetric data and expected diameter (R=0.07–0.23, P=0.32–0.76). The IVC–RPA distance correlated with height (R=0.87, P=0.0001), but was also variable. At the age of 2–4 years and body weight 12–15 kg IVC diameter and IVC–RPA distance are equal to 60–80% of adult values. Conduit thrombosis developed in two patients with unfavorable Fontan hemodynamics and oversized conduits. Conclusions: Considering the inferior vena cava size, ECFO may be performed at the age of 2–3 years and at a body weight 12–15 kg, when a hemodynamically optimal almost adult sized conduit can be implanted. Optimization of the conduit is necessary on the basis of the actual inferior vena cava diameter and IVC–RPA distance. Anticoagulation postoperatively should be considered to prevent conduit thrombosis in patients with suboptimal Fontan circulation