Introduction: The Bi-Directional Glenn (BDG) procedure, used in the surgical management of Hypoplastic Left Heart Syndrome (HLHS), involves the anastomosis of the superior vena cava (SVC) to the pulmonary artery, resulting in an abruptly increased central venous pressure (CVP). We hypothesize that this increase in CVP triggers an acute neurologic insult, promoting the development of hydrocephalus in the developing infant.
Methods: We identified 176 patients who underwent the BDG procedure between August 2006 and July 2013. Within our initial cohort, 25 patients had head imaging (CT, MRI, or ultrasound) performed both before and after the BDG. From these images, we retrospectively measured the Frontal-Occipital Horn Ratio (FOR)of the lateral ventricles, a well-validated indicator used to assess cerebral ventricular volume. Using central venous access catheter data we were able to assess pre-operative and post-operative pressure transducer data at discrete time-points. Paired t-tests and linear regression were used to evaluate our cohort. As this was a pilot study, statistical significance was set at p=0.10.
Results: The median age of our cohort was 3.5 months. Mean FOR was 0.393 before and 0.429 after the procedure. A paired two-tailed t-test demonstrated that BDG procedures are associated with an increased post-operative FOR (p<0.0001). Furthermore, a simple linear regression demonstrated a statistically significant association between increasing change in FOR following the BDG and CVP at 12 hours post Glenn procedure (p=0.003).
Conclusions: With the development of surgical palliation for single-ventricle congenital cardiac lesions, more children are surviving into adulthood. Our study is the first to demonstrate ventriculomegaly (FOR>0.42) developing in a cohort after the BDG. Further, we present a potential physiologic correlate with CVP after the Glenn procedure increasing with increased cerebral ventricle volume. This study has informed a prospective study currently in development, to evaluate the link between the BDG procedure and neurological outcomes.
Patient Care: This dramatic increase in lateral ventricle volume in children undergoing the Bi-Directional Glenn Procedure suggests that an acute neurologic insult could partially explain the well-established poor neurocognitive development of children requiring this procedure. While this is the first study identifiable in literature documenting this effect, this could be an opportunity for pre-operative neurosurgical evaluation or intervention to protect the developing brain from the dramatic increase in central venous pressure required for successful SVC to PA anastamosis in the BDG.
Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe the importance of validated measures of lateral ventricle volume in pediatric head imaging 2) Discuss, in small groups, the role of potential neurosurgical intervention in managing acute neurologic insults with increased ICP following the BDG 3) Identify an effective treatment for staged surgical palliative correction of HLHS, which dramatically alter CVP, thus likely altering CBF and CSF flow.