The Bilateral Bidirectional Glenn Operation As A Risk Factor Prior To Fontan Completion In Complex Congenital Heart Disease Patients

Introduction: The Glenn procedure is generally performed as a second-stage palliative procedure toward the completion of Fontan circulation in patients with a functionally univentricular heart. Safe Fontan completion requires normal ventricular function, competent atrioventricular valves, normal pulmonary arteries anatomy, and low pulmonary vascular resistances (PVRs), which is merely an estimation that considers both lungs as a single unit. Clinical observations revealed that patients who previously underwent bilateral bidirectional cavopulmonary anastomosis (b-BCPA) had a stormier postoperative course in respect to other patients with previous unilateral BCPA (u-BCPA) postoperatively after Fontan completion. This retrospective study was designed to compare and analyze the outcomes of patients following Fontan completion with previous u-BCPA versus b-BCPA. Patients and Methods: A total of 98 patients were divided into two groups based on the presence or absence of bilateral superior vena cava (SVC). Group 1 included 80 patients with unilateral SVC, and group 2 included 18 patients with bilateral SVC. Univariate and multivariate (SPSS) analyses were performed with regard to mortality and failure. P value of <.05 was considered as significant. Results: Prior to the total cavopulmonary anastomosis operation, the G1 and G2 had similar demographic and physiological findings, ages and weights were 4.3 1.72 years and 15.0 +/- 3.71 kg in G1 and 4.8 +/- 3.21 years and 17.5 +/- 9.76 kg in G2. Mean end-diastolic ventricular pressures (in mm Hg) were 10.50 +/- 2.86 in G1 and 10.28 +/- 3.07 in G2 and the mean PVRs (in Woods units) were 1.66 +/- 1.29 in G1 and 1.49 +/- 0.82 in G2. The Stormy postoperative course, Fontan failure, and early mortality were all significantly higher in G2 in respect to G1 (P value <.05). G1 mortality rate was 3.7%, 3 patients of 80, while in G2, the mortality rate was 22%, 4 patients of 18. Late Fontan failure rates were 6% for G1 patients where two patients developed pulmonary hypertension, two patients developed heart failure, and one patient had protein losing enteropathy (PLE), and 22% for the G2 patients of which two patients developed heart failure, one patient had PLE, and one patient had persistent low systemic venous saturation. Conclusions: Our results have demonstrated that patients after b-BCPA might have a tendency for worse outcomes upon Fontan completion. The b-BCPA is associated with pulmonary artery bifurcation stenosis and presents multiple sources of pulmonary blood flow where conventional PVR calculation might be imprecise and misleading since it considers the lungs as a single unit. Therefore, b-BCPA engenders correction of the conventional PVR calculation to consider each lung separately. Furthermore, the surgical approach for patients with persistent left SVC and univentricular heart should be modified.