Evaluation of neo-innominate connection in bilateral bidirectional Glenn patients using computational flow modeling

Patients with single ventricles undergoing bilateral bidirectional Glenn procedures present unique hemodynamic challenges due to distinct flow collisions compared with patients undergoing the unilateral Fontan. Flow-related changes in such patients may result in greater variation in power loss and hepatic flow differential (%) to branch pulmonary arteries that may result in pulmonary arteriovenous malformations and other Fontan-associated complications. This study aimed to analyze power loss and hepatic flow differential (%), along with its associated hemodynamics in patients undergoing the bilateral bidirectional Glenn under different physiological states and to evaluate the impact of a virtual neo-innominate vein connection on blood flow dynamics.

Thirty patients who underwent the bilateral bidirectional Glenn were retrospectively analyzed, and patient-specific 3-dimensional models created using magnetic resonance imaging data were created. Computational fluid dynamic simulations were performed at rest and exercise states. In patients with significantly unbalanced hepatic flow differential (hepatic flow differential to the left pulmonary artery outside a 35% to 65% range), a virtual (neo-innominate) connection was introduced to assess its impact on overall hemodynamics.

Nineteen patients exhibited significantly unbalanced hepatic flow differential with median hepatic flow differential to the left pulmonary artery 24%, which improved to 32% after virtual neo-innominate connection, indicating considerable improvement in several patients, although the overall change was not statistically significant (P = .059). Notably, 37% of these showed substantial improvement after neo-innominate creation, highlighting patient specificity. This was accompanied by nonstatistically significant changes in power loss (P = .14), which remained higher than values typically reported for unilateral Fontan configurations.

Our study showed that hemodynamics in patients undergoing the bilateral bidirectional Glenn are highly sensitive to anatomy and flow. A neo-innominate surgical modification can restore balanced hepatic flow differential (%) in select patients without a statistically significant increase in power loss but should be implemented selectively based on patient-specific anatomy and flow.