Abstract 10960: The Thoracic Duct is Well-Visualized on 3D-BSSFP Imaging in Patients With Fontan Circulation and Its Size and Tortuosity Are Associated With Worse Outcomes

Abstract

Introduction: Lymphatic complications are common in patients with Fontan circulation. 3D balanced steady-state free precession (3D-bSSFP) angiography by cardiovascular magnetic resonance (CMR) is widely adopted for cardiovascular anatomical assessment. We sought to determine the frequency of thoracic duct visualization using 3D bSSFP images and assess whether thoracic duct characteristics are markers of poor clinical outcomes. Methods: This was a retrospective, single-center study of patients with Fontan circulation who underwent CMR. Patients with repaired tetralogy of Fallot (rTOF) were included as a comparison. Thoracic duct characteristics included maximum diameter and a qualitative assessment of tortuosity (Figure). Clinical outcomes included protein-losing enteropathy (PLE), plastic bronchitis, listing for heart transplant, or death. A composite outcome was defined as presence of any of the above. Results: The study group was comprised of 189 Fontan patients and 36 rTOF patients (median age at CMR 16 years, IQR: 11-23 years). The thoracic duct diameter was larger (median 2.50 vs 1.95 mm, p<0.01) and more often well-visualized (65% vs 22%, p<0.01) in Fontan patients vs the rTOF group. The thoracic duct diameter was larger in Fontan patients with PLE (median 4.0 vs 2.5 mm, p=0.02) vs Fontan patients without PLE, and was more tortuous in Fontan patients with congestive heart failure (CHF) vs Fontan patients without CHF (moderate or greater tortuosity in 75% vs 28.5%, p=0.02). Larger thoracic duct diameter was associated with a lower ejection fraction (R= -0.24, p<0.01). The composite outcome was present in 6% of Fontan patients and was not associated with thoracic duct diameter (p=0.72) or tortuosity (p=0.09). Conclusions: The thoracic duct can be well visualized in 2/3 of patients with Fontan circulation on 3D-bSSFP images. Larger thoracic duct dimension and increased tortuosity are associated with co-morbidities experienced by Fontan patients.