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Systolic performance of the single ventricle, exercise capacity, and endothelial function in pediatric Fontan
Flora Nuñez Gallegos1, Daniel Bernstein1, Rajesh Punn1
1Stanford University School of Medicine, Stanford, CA 291 Campus Drive, Stanford, CA.
Insights
Pediatric Fontan patients show diminished single ventricle (SV) systolic function. Improved SV function correlates with better exercise capacity and endothelial function, highlighting potential benefits of interventions.
Area of Science:
- Pediatric Cardiology
- Congenital Heart Disease
- Single Ventricle Physiology
Background:
- Individuals with Fontan circulation face high mortality and morbidity by age 40.
- Poor exercise capacity and endothelial dysfunction are key drivers of disease progression in Fontan patients.
- Early assessment of single ventricle (SV) function is crucial for managing these complex patients.
Purpose of the Study:
- To evaluate the systolic function of the single ventricle (SV) in pediatric Fontan patients.
- To determine the association between SV systolic function, exercise capacity, and endothelial function.
- To provide baseline data for the RE-ENERGIZE FONTAN exercise intervention trial.
Main Methods:
- A cohort of 114 pediatric Fontan patients (ages 8-19) from an ongoing randomized trial.
- Assessment included 2D/3D echocardiography for SV systolic performance (strain, ejection fraction).
- Cardiopulmonary exercise testing (peak VO2) and reactive hyperemia index (RHI) for endothelial function were performed.
Main Results:
- Pediatric Fontan patients exhibited diminished SV systolic function at baseline.
- 2D strain and 3D ejection fraction (3D-EF) showed significant correlations with percent predicted peak VO2.
- 3D-EF was also positively correlated with endothelial function (RHI).
Conclusions:
- Baseline single ventricle systolic function is reduced in pediatric Fontan patients.
- Measures of SV systolic function, including 2D strain and 3D-EF, are associated with exercise capacity.
- 3D-EF demonstrates a relationship with endothelial function, suggesting its utility as a clinical marker.
Background:
By age 40, roughly half of the individuals with Fontan circulation will have died or undergone heart transplantation. Poor exercise capacity and endothelial dysfunction accelerate disease progression.
Objective:
This study aims to assess the systolic function of the single ventricle (SV) in pediatric Fontan patients entering an exercise intervention (RE-ENERGIZE FONTAN) and how it is associated with exercise capacity and endothelial function.
Methods:
This cohort comes from an ongoing randomized trial in Fontan patients, using live video conferencing for supervised exercise. Participants (ages 8-19) cleared for exercise underwent 2D/3D echocardiograms, cardiopulmonary testing, and endothelial function (RHI). 2D longitudinal strain (LS, right ventricle), 2D global longitudinal strain (GLS, left ventricle), and circumferential strain were measured with TomTec, and 3D ejection fraction (3D-EF) and 3D-GLS were calculated.
Results:
We have enrolled 114 Fontan patients. Median age was 12.7 years (IQR 10.2, 15.6). The median time from Fontan operation was 8.8 years (IQR 6.2, 12.0). Fifty-seven patients (50%) had a single right ventricle. SV systolic performance measures were: 2D-LS/GLS -15.6% ± 4.19%, circumferential strain was -18.7% ± 6.83%, 3D-EF 49.9% ± 7.26%, and 3D-GLS -16.8% ± 4.37%. Peak VO2 was 1,290 ± 502 mL/min, and percent predicted peak VO2 was 67.8% ± 15.6%. RHI was 1.44 ± 0.576. 2D-LS/GLS and 3D EF correlated with percent predicted peak VO2 (R = -0.28, P = .007 and R = 0.24, P = .019). 3D-EF correlated positively with RHI (R = 0.29, P = .0071).
Conclusions:
In this cohort of pediatric Fontan patients, SV systolic function was diminished at baseline, and there was a direct correlation between 2D strain and 3D-EF with percent predicted peak VO2, and additionally, 3D-EF with endothelial function.
Clinical Trial Number:
NCT04195451.
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