Stage 3 Fontan Operation Liver Ultrasound Study

Study Overview
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Brief Summary
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The purpose of this study is to compare the liver stiffness, which can be caused by congestion and fibrosis in pediatric patients before and after a Fontan heart operation. A new form of ultrasound elastography (Acoustic Radiation Force Impulse, or ARFI) will measure liver stiffness.

Detailed Description
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The Fontan repair for single ventricle congenital heart lesions consists of three stages. This surgery has enable pediatric patients who have the repair to live into adulthood. Stage 3 of the surgery introduces immediate congestion of blood in the liver by increasing central venous pressure (CVP). CVP is the blood pressure within the vena cava, a major blood vessel in the body. Many patients later develop progressive liver fibrosis (stiffness) possibly as a result of increased blood pressure. Liver stiffness is increased both by congestion and fibrosis. Liver fibrosis has significant health risks and may complicate the patient's future healthcare. There are no established, noninvasive means of detecting the liver fibrosis until it becomes severe. Acoustic radiation force impulse (ARFI) elastography, an ultrasound technique, can measure the stiffness of the liver safely from outside the body. The investigators hypothesize that liver stiffness will be increased by stage 3 of the Fontan operation due to onset of liver congestion. Using ARFI, the investigators will measure liver stiffness before and immediately after stage 3 of the Fontan operation, when congestion of blood is likely the only contributor to any change in liver stiffness. The investigators will follow the trend of liver stiffness at six months by repeating the ARFI imaging.

Official Title
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Noninvasive Detection of Liver Injury Immediately Following the Fontan Operation: the Role of Ultrasound-Based Elastography

Conditions
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Fontan Operation

Intervention / Treatment
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* Device: ARFI Ultrasound


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Pediatric patients ages 0-17 Patients presenting to the University of Michigan for evaluation just before undergoing stage 3 of the Fontan operation Exclusion Criteria: Patients over the age of 17 Patients who have chronic liver disease (elevation of ALT, AST, or Bilirubin greater than two times the upper limits of normal >4 weeks) Patients who have evidence of liver enlargement or nodularity on prior ultrasound imaging Patients who have a history of portal vein or hepatic vein thrombosis Patients (parents) who are unwilling to read and sign the informed consent document

Ages Eligible for Study
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Maximum Age: 17 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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Design Details

Primary Purpose: Diagnostic
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: ARFI Ultrasound<br>This study uses ultrasound scanning with acoustic radiation force impulse shear wave velocity imaging to measure pediatric liver fibrosis. Patients will be children who have had the Fontan operation. This is a non-invasive scan that uses sound waves to create images. | Device: ARFI Ultrasound<br>* This research scan uses acoustic radiation force impulse (ARFI) shear wave velocity imaging (SVI). This is a new ultrasound technology in which unique sound waves create the images/pictures of the liver beng examined/scanned. This ultrasound scan will take approximately 10 minutes to complete.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Shear Wave Speed (Liver Stiffness) | ARFI shear wave speed measurements were done on the right lobe of the liver. Measurement units are m/s (meters per second). A total of 8 measurements were performed on each subject at each time point.The 8 values were performed on each subject and averaged. | 0-6 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| IVC Pressure | Blood pressure in the IVC, the interior vena cava, was measured from a central line placed for patient care. | Baseline and Follow Up Number 1 (approximately 24 -72 hours later) |