The aim of this study is to investigate whether venous compression garments increase exercise stroke volume in patients with Fontan circulation. To address this aim, we will test the following hypotheses: 1. Acute and chronic external venous compression will increase exercise stroke volume in patients with Fontan circulation. 2. Patients with significant venous varicosities will have a greater response to venous compression. Participants will: * Undergo submaximal exercise testing in MRI to measure venous return and exercise stroke volume with and without the wearing of compression garments * Undergo submaximal exercise testing on a seated upright exercise ergometer with concurrent measurement of stroke volume with and without the wearing of compression garments * A subset of participants will repeat both testing visits after wearing compression garments for 2-weeks during waking hours. Participants will: * Undergo submaximal exercise testing in MRI to measure venous return and exercise stroke volume with and without the wearing of compression garments * Undergo submaximal exercise testing on a seated upright exercise ergometer with concurrent measurement of stroke volume with and without the wearing of compression garments * A subset of participants will repeat both testing visits after wearing compression garments for 2-weeks during waking hours.
Study Day 1 - Consent, Screening and Garment Measurements: Following assessment of participant eligibility, all participants will undergo leg venous ultrasound assessment and abdominal-foot measurements for the custom making of compression garments. Study Day 2 - MRI: Study participants will undergo comprehensive cardiovascular MRI using a 3T MRI scanner with and without compression garments and exercise. Study Day 3 - Cardiovascular \& Exercise Testing Day: All participants will undergo comprehensive cardiovascular structure and function assessments at rest and during exercise with and without the wearing of compression garments. Baseline testing will include dual x-ray absorptiometry (DEXA), pulmonary function testing, comprensive vascular assessments and echocardiography. During exercise at two submaximal workloads, the study team will measure blood pressure, oxygen uptake and cardiac output.
Study Type
INTERVENTIONAL
Allocation
NON_RANDOMIZED
Purpose
OTHER
Masking
NONE
Enrollment
20
Acute and 2-week effects of compression garments
Acute effects without compression garments
Change in Stroke Volume with Exercise
The change in single ventricular stroke volume from rest to moderate intensity exercise with compression garments during baseline testing
Time frame: Rest (20 minutes), Exercise (10 minutes)
Change in Stroke Volume with Exercise
The change in single ventricular stroke volume from rest to moderate intensity exercise without compression garments during baseline testing
Time frame: Rest (20 minutes), Exercise (10 minutes)
Change in Stroke Volume with Exercise
The change in single ventricular stroke volume from rest to moderate intensity exercise following 2 weeks of wearing compression garments.
Time frame: Rest (20 minutes), Exercise (10 minutes) at 2-weeks follow-up testing
The Acute Effect of Compression Garments on Stroke Volume during Exercise
The difference in the change in single ventricular stroke volume during moderate intensity exercise between baseline testing with (outcome #1) and without (outcome #2) garments
Time frame: Rest (20 minutes) and Exercise (10 minutes) repeated during baseline testing
The Chronic Effect of Compression Garments on Stroke Volume during exercise
The difference in the change in single ventricular stroke volume during moderate intensity exercise between baseline testing without garments (outcome #2) and following 2 weeks of wearing compression garments (outcome #3) in patients with Fontan Circulation.
Time frame: Rest (20 minutes) and Exercise (10 minutes) completed during baseline and during follow-up testing
Change in Venous Return with Exercise
The change in inferior vena cava flow from rest to moderate intensity exercise with compression garments using MRI during baseline testing
Time frame: Rest (10 minutes) and Exercise (5 minutes)
Change in Venous Return with Exercise
The change in inferior vena cava flow from rest to moderate intensity exercise without compression garments using MRI during baseline testing
Time frame: Rest (10 minutes) and Exercise (5 minutes)
Change in Venous Return with Exercise
The change in inferior vena cava flow from rest to moderate intensity exercise following 2 weeks of wearing compression garments using MRI
Time frame: Rest (10 minutes) and Exercise (5 minutes)
The Acute Effect of Compression Garments on Changes in Venous Return with Exercise
The difference in the change in inferior vena cava flow during moderate intensity exercise between baseline testing with (outcome #6) and without (outcome #7) garments
Time frame: Rest (10 minutes) and Exercise (5 minutes) repeated during baseline testing
The Chronic Effect of Compression Garments on Changes in Venous Return with Exercise
The difference in the change in inferior vena cava flow during moderate intensity exercise between baseline testing without garments (outcome #7) and following 2 weeks of wearing compression garments (outcome #8) in patients with Fontan Circulation.
Time frame: Rest (10 minutes) and Exercise (5 minutes) completed during baseline and during follow-up testing
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