What is the clinical evidence from this study?

Study design: Cross-Sectional. Population: Fontan circulation (n=44). Primary outcome: Peak oxygen uptake (V̇O₂peak).

March 28, 2026Open Access

What Limits Cardiorespiratory Fitness in Adolescents with Fontan Circulation: An Integrated Hemodynamic and Pulmonary Perspective

Key Result

In adolescents with Fontan circulation, lower resting ventricular end-diastolic pressure and greater height were independently associated with higher peak oxygen uptake (R2=0.61).

Key Points

The study aims to explore what affects cardiorespiratory fitness in adolescents with Fontan circulation, focusing on hemodynamic and pulmonary factors.
Conducted a cross-sectional study with 44 adolescents with Fontan circulation.
Performed cardiopulmonary exercise testing, heart catheterization, and pulmonary function assessments.
Used multiple linear regression to analyze peak oxygen uptake based on various predictors.
The model explained 61% of the variance in absolute peak oxygen uptake (V̇O₂peak).
Lower end-diastolic pressure and greater height were linked to higher V̇O₂peak.
Exercise oscillatory ventilation was found in 50% of participants but was not associated with peak oxygen uptake.

Study Design

Type

Cross-Sectional (n=44)

Multicenter

Structured PICO

Population

44 adolescents (median age 16.6 years) with Fontan circulation

Outcome

Peak oxygen uptake (V̇O₂peak)surrogate

In adolescents with Fontan circulation, lower resting ventricular end-diastolic pressure and greater somatic growth are independently associated with higher cardiorespiratory fitness, highlighting the importance of ventricular diastolic function.

Limitations

Modest sample size
Incomplete datasets necessitated restriction of regression analyses to complete-case models
Relatively preserved physiological profile may limit applicability to patients with more advanced failure
Cross-sectional design precludes causal inference
Catheterization data obtained at rest may not fully reflect exercise hemodynamics
Data on lean body mass was not available

Abstract

Cardiorespiratory fitness (CRF) is strongly associated with morbidity and mortality in patients with Fontan circulation. However, the factors influencing CRF during adolescence remain incompletely understood. The primary aim of this study was to investigate the associations between CRF and ventricular function represented by end-diastolic pressure (VEDP), the transpulmonary pressure gradient (TPG), somatic growth (height) and pulmonary diffusing capacity (DLCO/VA). The secondary aim was to assess the prevalence of exercise oscillatory ventilation (EOV) and its physiological associations. In this national, cross-sectional study, 44 adolescents (median age 16.6 years) with Fontan circulation underwent cardiopulmonary exercise testing, heart catheterization and pulmonary function assessment. Peak oxygen uptake (V̇O₂peak) was modelled as the dependent variable in a multiple linear regression with VEDP, TPG, height, and DLCO/VA as predictors. Logistic regression was used to identify physiological associations of EOV. The multiple regression model for absolute V̇O₂peak explained 61% of the overall variance. Lower VEDP and greater height were independently associated with higher V̇O₂peak. When V̇O₂peak was expressed relative to body mass, TPG also became associated with higher V̇O₂peak, while greater height and lower VEDP remained associated. This model explained 30% of the variance. DLCO/VA was not independently associated with V̇O₂peak. EOV was observed in 50% of patients but showed no association with V̇O₂peak, hemodynamic, or pulmonary variables. In adolescents with Fontan circulation, lower resting VEDP and somatic growth were associated with higher CRF, reflecting more efficient hemodynamics. Pulmonary diffusing impairment and EOV were common but not significantly associated with lower CRF.

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