This clinical trial is focused on studying the effects of the medication Theophylline in individuals with a specific type of heart condition known as univentricular congenital heart disease that has been treated with a Fontan-type surgical palliation. The medication being tested is called Theo-Dur 200mg depottablett, which is a prolonged-release tablet taken orally. The purpose of the study is to explore the feasibility and safety of a 12-week treatment plan, which includes adjusting the dosage remotely and monitoring heart rhythm during the treatment phase.
Participants in the study will be adolescents aged 16 to 25 years who have undergone the Fontan procedure. The study will estimate the effect of 12 weeks of oral treatment with Theophylline on exercise capacity. Throughout the study, participants will be monitored for any side effects and changes in their ability to exercise. The study will also assess differences in oxygen uptake, which is a measure of how well the body uses oxygen during physical activity, before and after the treatment.
In addition to exercise capacity, the study will evaluate other health aspects such as quality of life through questionnaires, heart function using echocardiography (a type of ultrasound for the heart), and breathing capacity. Participants will also undergo a home-based sleep study to check for changes in sleep patterns. The study aims to provide valuable insights into the potential benefits and safety of Theophylline for young people with this heart condition.



Norway