Lymphatic abnormalities have been documented on magnetic resonance lymphangiography in patients with functionally univentricular circulation.

The aim of this study is to evaluate associations between findings on magnetic resonance lymphangiography, cardiac catheterisation and functional phenotype in patients with Fontan-Kreutzer circulation.

Between January 2017 and October 2019, seven patients with Fontan-Kreutzer circulation (16.57 ± 7.10 years) were enrolled following ethical committee approval and attainment of informed consent. Clinical data, consecutive magnetic resonance imaging and cardiac catheterisation findings were reviewed. Qualitative lymphatic abnormality types were defined as: 1 – Little or none; 2 – Localised to the supraclavicular region; 3 – Extending into the mediastinum; and 4 – Extending into the lung. Pulmonary hypertension was defined as a transpulmonary gradient > 6 mmHg. Quantitative data were assessed using Mann–Whitney U tests, and p < 0.05 was considered statistically significant.

Patients with lymphatic abnormalities categorised type 1 or 2 and transpulmonary gradient ≤ 6 mmHg had a normal functional phenotype, while those with type 3 or 4 and transpulmonary gradient > 6 mmHg had a failing functional phenotype.

Magnetic resonance lymphangiography in patients with Fontan-Kreutzer circulation and pulmonary hypertension revealed lymphatic abnormalities types 3–4, indicative of a failing functional phenotype compared to patients without pulmonary hypertension. If validated in larger studies, these results suggest the potential utility of this extracardiac biomarker for improving risk stratification. Integration of lymphangiography and transpulmonary gradient with functional class, atrioventricular valve function, and ejection fraction allowed for the categorisation of three distinct functional phenotypes, which may be valuable for future analyses.