Cerebral ventriculomegaly after the bidirectional Glenn (BDG) shunt: a single-institution retrospective analysis

Purpose: The bidirectional Glenn (BDG) procedure involves the anastomosis of the superior vena cava (SVC) to the pulmonary artery, increasing central venous pressure (CVP). We hypothesize that this increase in CVP triggers an acute neurologic insult, leading to ventriculomegaly. Methods: In this retrospective analysis in a tertiary care children’s hospital, we identified 167 patients who underwent the BDG procedure between August 2006 and July 2013. Within this initial cohort, 24 patients had head imaging (CT, MRI, or ultrasound) performed both before and after the BDG. Results: From head imaging available from these 24 patients, we measured the frontal-occipital horn ratio (FOR), a well-validated measure of lateral ventricle size. Using central venous catheter data, we assessed postoperative CVP at 12, 24, and 48 h. Paired t tests and linear regression were used to evaluate our cohort. Median age at surgery was 4.9 months. Paired analysis revealed that median FOR significantly increased between preoperative (median 0.38, IQR 0.37–0.41) and postoperative (median 0.42, IQR 0.40–0.45) head images (p = 0.005). Increasing change in FOR was associated with increased 12-h (R² = 0.369, p = 0.003) but not 24- or 48-h postoperative CVP. Conclusions: To our knowledge, our study is the first to demonstrate ventriculomegaly developing after the BDG. Physiologically, increasing CVP after the BDG was associated with greater change in lateral ventricle size. This supports the contention that increasing CVP produced during the BDG may damage the developing brain. This study has informed a prospective evaluation of a link between the BDG procedure and neurologic outcomes.