Fontan Circulation

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.

The purpose of this research is to determine whether treatment with the study drug dapagliflozin for 3 months affects peripheral venous pressure at rest and during exercise in adults with failing Fontan circulation.

This is a single center, open-label, prospective, investigation to quantify the effects liver congestion and fibrosis has on hepatic drug metabolism and transport in children, adolescents, and young adults with Fontan circulation.

In the Swedish registry for congenital heart defects, SWEDCON, over 230 patients with single-ventricle circulation are registered in the adult section. Congenital heart defects affect career choices, family planning, and leisure activities. Questions regarding heredity and pregnancy are common. The impact of Fontan circulation on reproductive health and fertility needs to be illuminated, and additional studies are required from both medical and psychosocial perspectives.Cognitive impairment is common among patients with congenital heart defects but is likely an overlooked cause of long-term illness. Objective To study a large national population (n=200) of adults with Fontan circulation and their potential partners regarding. * the prevalence and explanatory factors for sexual dysfunction and infertility in women and men with Fontan circulation (Study A). * the outcomes of pregnancy, choice of delivery mode, and complications in patients with Fontan circulation (Study B). * the experiences and perceptions of becoming parents among women (n=20) and men (n=20), as well as elucidate reasoning and family planning among women and men (n=20) who have not become parents (Study C). * Investigate the prevalence and explanatory factors for (Sub-study D): * Fatigue * In-depth cognitive screening to describe specific cognitive functions such as auditory memory, visuospatial memory, attention, cognitive speed, and executive functions. The aim of this research is to gain more knowledge in an area that has been relatively underexplored, thus improving care for women and men with congenital heart defects.