Abstract No. 546 Thoracic duct variants: what are they, and which ones pose the greatest challenge for cannulation?

Abstract

Thoracic duct embolization (TDE) is a minimally invasive treatment for chylous pleural effusions and, in many cases, is used as a first-line intervention. Arguably the most difficult part of a TDE is percutaneously accessing the thoracic duct, a task made even more difficult in the presence of anatomic variants. We describe several thoracic duct anatomic variants and which variants posed the greatest challenge in cannulation. 75 patients undergoing TDE between 2010 and 2018 were identified. Imaging was reviewed to determine thoracic duct anatomy. Procedural and clinical notes were reviewed to determine patient outcomes. Of the 75 patients, 50 patients (66.7%) had standard thoracic duct anatomy, 13 (17.3%) had an absence of cisterna chyli (CC), 5 (6.7%) had a persistent right thoracic duct, 3 (4%) had a proximal duplication of the thoracic duct, 2 (2.7%) had plexiform ducts, 2 (2.7%) had persistent left thoracic duct. Of the patients with standard thoracic ducts, 40 cannulation attempts were made and 30 were successful (75%). The most common variant encountered, absence of the CC posed the greatest challenge when performing percutaneous access. In the 13 patients with an absence of a CC, 9 cannulation attempts were made with only 4 succeeding (44%). Cannulation was not attempted in 4 patients because of a lack of an adequate percutaneous target. In the two patients with plexiform ducts, cannulation was attempted in both but only 1 was successful. In the patients with persistent right-sided course, persistent left-sided course, and a proximal thoracic duct duplication, all cannulation attempts were successful. Knowledge of commonly encountered thoracic duct variants can help predict the likelihood of a challenging cannulation. The absence of CC and plexiform duct may be predictive of technical failure of the procedure. Novel techniques or procedural adjustments are necessary to address thoracic duct variants encountered during TDE.