New Indicator for the Fontan Operation: Diameters of the Pulmonary Veins in Patients with Univentricular Heart

Background:Operative survival after the Fontan procedure is good; however, there are some patients with disappointing results, especially those with atrial isomerism. Objectives: We tested whether the diameter of the pulmonary veins, which is reported as a useful indicator of pulmonary blood flow, predicts operative results after the Fontan operation. Patients and Methods: We evaluated 30 consecutive patients undergoing either the bidirectional Glenn anastomosis (BDG) or the Fontan operation. Age at operation ranged from 3 to 81 months (mean 30). Diagnosis was right or left isomeric heart in 15 patients, double-outlet right ventricle in 4 and various other malformations in 11. BDG was performed in 16 patients and the Fontan operation in 14 patients. The diameters of the pulmonary veins were measured proximal to the entrance into the atrium in the late phase of a pulmonary arteriogram. The pulmonary vein (PV) index (in mm2/m2) was calculated from the sum of the cross-sectional areas of these veins divided by the body surface area. Results: Of the patients undergoing BDG (± ancillary procedures), 12 had successful results and 4 had unsuccessful results. The PV index for hemodynamically successful patients was 361 ± 153 and 275 ± 60 mm2/m2 (mean 5 SD) for unsuccessful patients (p = 0.30). Of the patients who underwent the Fontan operation, 13 had successful and 1 had unsuccessful results. The PV index for successful patients was >285 mm2/m2 and 137 mm2/m2 for the nonsuccessful patients. The new pulmonary vascular resistance (PVR) calculated by using the PV index (mean pressure difference between the pulmonary artery and the atrium/PV index) for BDG patients with successful or unsuccessful results was 2.0 ± 0.5 or 3.5 ± 0.2 mmHg/mm2 per m2, respectively (p < 0.01). The new PVR for Fontan patients with successful results was <2.0 mmHg/mm2 per m2, while that for the patient with an unsuccessful result was 4.4. The new PVR completely separated patients into successful and unsuccessful groups, while conventionally calculated PVR did not (p = 0.63). Conclusions: PV index appears to be a useful morphological indicator of pulmonary blood flow and “new” PVR may improve the decision-making strategy for patients presenting with univentricular heart, especially those associated with isomeric heart.