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 a trial isomerism. Objectives: We tested whether the diameter of the pulmonar y veins, which is reported as a useful indicator of pulmonary blood flow, p redicts operative results after the Fontan operation. Patients and Methods: We evaluated 30 consecutive patients undergoing either the bidirectional G lenn anastomosis (BDG) or the Fontan operation. Age at operation ranged fro m 3 to 81 months (mean 30). Diagnosis was right or left isomeric heart in 1 5 patients, double-outlet right ventricle in 4 and various other malformati ons 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 th e entrance into the atrium in the late phase of a pulmonary arteriogram. Th e pulmonary vein (PV) index (in mm(2)/m(2)) 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 hemodyn amically successful patients was 361 +/- 153 and 275 +/- 60 mm2/m2 (mean +/ - SD) for unsuccessful patients (p = 0.30). Of the patients who underwent t he Fontan operation, 13 had successful and 1 had unsuccessful results. The PV index for successful patients was >285 mm(2)/m(2) and 137 mm(2)/m(2) for the nonsuccessful patients. The new pulmonary vascular resistance (PVR) ca lculated by using the PV index (mean pressure difference between the pulmon ary artery and the atrium/PV index) for BDG patients with successful or uns uccessful results was 2.0 +/- 0.5 or 3.5 +/- 0.2 mmHg/mm(2) per m(2), respe ctively (p < 0.01). The new PVR for Fontan patients with successful results was <2.0 mmHg/mm(2) per m(2), while that for the patient with an unsuccess ful result was 4.4. The new PVR completely separated patients into successf ul and unsuccessful groups, while conventionally calculated PVR did not (p = 0.63). Conclusions: PV index appears to be a useful morphological indicat or of pulmonary blood flow and "new" PVR may improve the decision-making st rategy for patients presenting with univentricular heart, especially those associated with isomeric heart.