The thoracic duct and the Fontan patient

Area of Science:

• Pediatric Cardiology
• Lymphatic Imaging
• Thoracic Duct Ultrasound

Background:

• Elevated central venous pressure (CVP) and lymphatic drainage abnormalities are linked to severe Fontan complications like protein-losing enteropathy (PLE) and plastic bronchitis (PB).
• Systematic studies on thoracic duct (TD) and lymphatic circulation in children are limited, with no established cervical TD normative values.

Purpose of the Study:

• To systematically study ultrasonographic thoracic duct (TD) imaging in children.
• To establish normative values for cervical TD in pediatric populations.
• To compare TD dimensions in children with Fontan palliation versus healthy controls.

Main Methods:

• Prospective ultrasonographic imaging of the TD was performed during routine echocardiograms in children aged 5-21 years.
• TD insertion to the central venous system (lympho-venous junction) was assessed using an S12-4 MHz transducer.
• TD ostia and proximal arch measurements were taken, with adjustments for shape variability.

Main Results:

• Seventy-nine subjects (58 controls, 21 Fontan patients) were studied.
• Fontan patients demonstrated significantly larger TD ostial diameters when normalized by body surface area compared to controls (2.6 mm/m² vs. 2 mm/m², P=.04).

Conclusions:

• This is the first systematic study of ultrasonographic TD imaging in children.
• Fontan patients exhibit larger TD diameters, suggesting impaired lymphatic circulation.
• Sonographic TD features may correlate with functional status in Fontan patients, warranting further investigation.