Impact of bilateral bidirectional Glenn anastomosis on staged Fontan strategy and Fontan circulation

Objectives: The aim of this study was to identify the impact of bilateral bidirectional Glenn (BBDG) anastomosis on staged Fontan strategy and late Fontan circulation.

Methods: Of 267 patients who underwent bidirectional Glenn prior to Fontan completion between 1989 and 2013, 62 patients (23%) who underwent BBDG were enrolled in this study. Age at operation was 0.84 years (25th-75th percentile: 0.58-1.39). Thirty-three patients had heterotaxy syndrome (53%). The mean follow-up period was 12.7 ± 8.1 (max. 30.6) years.

Results: The overall survival rate at 15 years was 73%. Although 49 patients (79.0%) went on to Fontan completion, 12 patients (19.4%) died without achieving it. Thrombus formation and poor development in a central pulmonary artery were not observed, but obstruction of the superior vena cava (SVC) occurred in 8 patients (13%), mainly those with right atrial isomerism (P = 0.037). SVC obstruction was not, however, a risk factor for mortality (P = 0.097) or Fontan completion (P = 0.41). The shape of BBDG anastomosis, symmetricity of pulmonary blood flow, impingement of caval blood flow returning from the superior and inferior vena cavae or coexisting interrupted inferior vena cava with azygos or hemi-azygos continuation did not affect late Fontan outcomes, such as overall survival, freedom from protein-losing enteropathy or pulmonary arterio-venous malformation rates.

Conclusions: SVC obstruction after BBDG frequently occurred, mainly in patients with right atrial isomerism; however, its direct impact on prognosis or achieving Fontan completion was not identified. Once Fontan circulation was established, the arrangement of the Fontan pathway did not affect late Fontan outcomes.