Fontan Imaging Biomarkers (FIB) Study

The goal of the Fontan Imaging Biomarkers (FIB) study is to identify the associations of blood and urine biomarkers to imaging parameters of ventricular mechanics.

This study has the following research questions: 1. What is the reproducibility of ventricular systolic function measurements (including ventricular strain) in Fontan patients using echocardiography (Echo) and cardiac magnetic resonance imaging (CMR)? 2. What is the reproducibility of ventricular diastolic function measurements (including tissue Doppler and strain rate) in Fontan patients using Echo and CMR? 3. Is there a correlation between ventricular function measurements and circulating biomarkers (including galectin-3 levels, NT-proBNP, ST2, and MELD-XI score)?

Inclusion Criteria:

* All patients with Fontan circulation undergoing clinically indicated CMR at Boston Children's Hospital will be considered for the study

Exclusion Criteria:

* Inadequate imaging quality to perform proposed analysis
* Patients \<15 kg will be excluded to simplify compliance with BCH minimal risk research blood draw volume guidelines (minimal risk is defined as \< 5% total blood volume)