Fibrosis and the Fontan

Eligibility Criteria

• * Single Ventricle (SV) Patients
• * Subjects between 1 and ≤ 6 years of age of either gender.
• * Either single left or single right ventricle.
• * Subjects who are scheduled to undergo a Fontan operation at CHOP.
• * Parents signing informed consent.
• * Subjects who were enrolled in this study in Cohort 2 and are either non-compliant with the medication, no longer want to take the medication, or have an AE that requires them to stop the medication, and patient's family would like to continue participation
• * Patients were on study medication for 6 weeks or less.
• * The principal investigator deems it appropriate for the patient to switch to the observational arm.
• * Patients signing the observational informed consent form.
• * Subjects between 1 and ≤6 years of age of either gender.
• * Either single left or single right ventricle.
• * Subjects who are planned to undergo a Fontan operation at CHOP.
• * Patients in other interventional studies approved by principal investigator.
• * Patients signing the observational informed consent form.
• * Subjects between 1 and ≤ 6 years of age of either gender.
• * Either single left or single right ventricle.
• * Subjects who are scheduled to undergo a Fontan operation at CHOP.
• * Parents signing informed consent.
• * Subjects between 1 and ≤ 6 years of age of either gender
• * Subjects with normal ventricular function and normal livers who present to CMR for clinical indications and require anesthesia.
• * Receiving contrast for clinical purposes. No control patient will receive contrast for research purposes.
• * Parents signing informed consent.
• * Subjects with any condition judged by the patient's physician that would cause this trial to be detrimental to the patient.
• * Any contradiction to a sedated CMR (i.e. presence of a pacemaker).
• * Patient currently taking spironolactone or eplerenone
• * Subjects in any study that would preclude participation in the study by altering results
• * Subjects with any condition judged by the patient's physician that would cause this trial to be detrimental to the patient.
• * Any contradiction to a sedated CMR (i.e. presence of a pacemaker).
• * Subjects in any study that would preclude participation in the current study.
• * Subjects with any condition judged by the patient's physician that would cause this trial to be detrimental to the patient.
• * Any contradiction to a sedated CMR (i.e. presence of a pacemaker).
• * Patient currently taking spironolactone or eplerenone
• * Subjects in any study that would preclude participation in the current study or studies not approved by principal investigator.
• * Subjects with any condition judged by the patient's physician that would cause this trial to be detrimental to the patient.
• * Any contradiction to a sedated CMR (i.e. presence of a pacemaker).
• * Patient currently taking spironolactone or eplerenone
• * Subjects with hyperkalemia or Addison disease;
• * Subjects on enalapril or other angiotensin receptor blockers
• * Subjects with a history of hypersensitivity to spironolactone suspension or any component of the formulation
• * Subjects with a clinically documented diagnosis of severe renal insufficiency (implying estimated glomerular filtration rate (eGFR) \<30 mL/minute/1.73 m2).
• * Subjects in any study that would preclude participation in the study by altering results
• * Any condition judged by the patient's physician that would cause this trial to be detrimental to the patient.
• * Any contradiction to a sedated CMR (i.e. presence of a pacemaker).
• * Patient currently taking spironolactone, eplerenone or an angiotensin converting the enzyme inhibitor/angiotensin receptor blocker.