Diffuse Myocardial Fibrosis in Fontan Patients

Study Overview
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Brief Summary
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The purpose of this protocol is to measure the relaxation of the heart in subjects with single ventricles who have undergone the surgical Fontan procedure. We will do this by measuring relaxation with MRI, echocardiography, and cardiac catheterization and compare to blood levels that measure heart scarring. We will also measure relaxation before and after boluses of intravenous (IV) fluids to see if the relaxation changes when there is more fluid in the heart. Measurements of heart relaxation will be obtained from the MRI, echocardiogram, and cardiac catheterization for each patient and compared to blood markers of heart scarring. We aim to compare all of these measurements to see if we can accurately identify heart scarring and, if present, how much it correlates with impaired heart relaxation.

Official Title
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Heart Failure and Fibrosis in Adult Congenital Heart Patients With a Single Ventricle and Prior Fontan Operation.

Conditions
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Congenital Heart Disease, Single Ventricle, Myocardial Fibrosis

Participation Criteria
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Eligibility Criteria
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Inclusion criteria: adult patients (age ≥18) with a previous Fontan procedure (including all variants) referred for catheterization. This includes individuals with tricuspid atresia, double inlet left ventricle, unbalanced atrioventricular septal defect, and pulmonary atresia with intact septum. Control subjects will be selected from individuals referred to the lab for evaluation/closure of a patent foramen ovale (PFO). All subjects must be willing to participate in all portions of the study and provide written informed consent. Exclusion criteria: contraindications to MRI such as ferromagnetic objects in the chest, claustrophobia, or contraindication to gadolinium contrast (estimated creatinine clearance < 30 ml/min/1.73m2). Fontan patients with a morphologic right ventricle (namely hypoplastic left heart after a Norwood palliation) will be excluded, because of the disproportionate risk of systolic dysfunction in the morphologic right ventricle.33 Control patients with hypertension, diabetes, coronary disease, or reduced systolic function will be excluded.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 90 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Controls<br>Patients undergoing catheterization for other reasons who have a normal biventricular heart. | |
| Single ventricle Fontan<br>Patients with a single functional ventricle (excluding hypoplastic left heart syndrome) palliated with a Fontan type operation involving passive blood flow to the lungs. | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Myocardial fibrosis measured by the extracellular volume fraction | All patients will have measurements of pressure and volume before and after IV fluid administration, as well as computation of their extracellular volume fraction. | 1 day of single observation | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Myocardial fibrosis, Congenital heart disease, Diastolic dysfunction