Identification of high-risk Fontan candidates by intraoperative pulmonary flow study

Background: Pre-Fontan risk stratification is still less than optimal. We aimed to evaluate the effectiveness of intraoperative pulmonary flow study (IOFS), in combination with conventional preoperative evaluation, in the identification of high-risk candidates for the Fontan operation.

Method: Data from 37 patients (age: 38.1 ± 4.9 months) who underwent the Fontan operation with IOFS were retrospectively reviewed. After anastomosing the Gore-Tex vascular graft to the confluent pulmonary artery, IOFS was performed through the graft at various cardiac indices (CI) (1-4 L/min/m²) generated from a roller pump. Mean pulmonary artery pressure (mPAP) and left atrial pressure (LAP) were recorded. The patients were divided into two groups: those who required Fontan circuit fenestration (group Ff) and those who did not (group Fn).

Results: Eleven patients (29.7%) required fenestration, intraoperatively (n = 4) and postoperatively (n = 7), due to hemodynamic instability. Heterotaxy syndrome (P = 0.005) and atrioventricular valvar regurgitation (P = 0.04) were more frequent, and ventricle posterior wall thickness (VPWT) was higher (P = 0.024) in group Ff. On IOFS, the increase in mPAP by CI was sharper in group Ff than in group Fn (P < 0.001) owing to an increase in LAP. On multivariable analysis, mPAP at a CI of 3.0 L/min/m² from IOFS was the only predictor of fenestration and correlated with preoperative VPWT (R = 0.543, P = 0.001).

Conclusions: IOFS may be helpful to identify high-risk Fontan candidates, and high mPAP at CI of 3.0 L/min/m² on IOFS is a significant predictor of the requirement for fenestration. VPWT is an important preoperative risk factor which correlates with the IOFS results.