Fontan CirculationMuscle in TCPCNCT07420660
Muscle Function in Patients With Single-chamber Heart
An observational study of Fontan Circulation, run by Karolinska Institutet at 1 site in Sweden.
Trial summary
Groundbreaking cardiac surgery has significantly improved survival rates for patients with single-chamber hearts. However, despite these life-saving interventions, the long-term prognosis remains concerning, with an increased risk of heart failure, sudden cardiac death, and reduced quality of life. Read more about this study
- Who is it for?
- Ages 16 to 50 years
- Conditions the study is for
- Fontan Circulation
- How many people
- 34 participants
- Where
- 1 siteSweden
- Study dates
- 18 Feb 2026to 8 Jun 2026
- Phase
- Observational
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 16 to 50 years
- All sexes
- No healthy volunteers
- Child, Adult
Study population: Patients linked to the Region Stockholm outpatient clinic
Who may be able to join
- Diagnosis of a Fontan circulation: individuals who have undergone the Fontan procedure with only one functioning systemic ventricle, confirmed by medical records or attending physician.
- Stable clinical status: patients should be clinically stable without significant cardiovascular or renal dysfunction as determined by clinical examinations.
- Age range: 16-50 years.
- Ability to exercise: Participants must be physically able to participate in the exercise protocol according to a preliminary medical examination.
- Controls: Age and sex-matched. Healthy (no chronic diseases, assessed by health questionnaire and interview).
Who cannot join
- Recent surgery or hospitalization: individuals who have undergone cardiovascular surgery or hospitalization within six months prior to inclusion.
- Severe functional limitations: Patients with clear functional limitations unrelated to Fontan physiology, such as musculoskeletal disorders.
- Significant comorbidities: Serious non-cardiac comorbidities that may independently affect work capacity, such as advanced pulmonary disease.
- Contraindications for exercise testing: Conditions that contraindicate physical testing, such as uncontrolled cardiac arrhythmias or severe heart failure (New York Heart Association III-IV).
Trial locations and contacts
1 site in 1 country.
About this study
Official title: Importance of Muscle Function for Patients With Single-chamber Heart
Groundbreaking cardiac surgery has significantly improved survival rates for patients with single-chamber hearts. However, despite these life-saving interventions, the long-term prognosis remains concerning, with an increased risk of heart failure, sudden cardiac death, and reduced quality of life. The absence of a chamber that pumps blood to the lungs means individuals must rely on their leg muscles to passively return blood and oxygenate the lungs. Unfortunately, studies indicate reduced muscle mass and function in these patients.
The aim is to clarify the complex interplay between single-chamber circulation and muscle function, paving the way for targeted interventions such as muscle strengthening training for this unique patient group. Our hypothesis is that muscle mass and function correlate with circulatory limitations, and that muscle strengthening training could, over time, improve both muscle and circulatory function simultaneously.
Read more
The first part of the project includes tests for maximal oxygen uptake, heart and circulatory function, muscle strength, muscle mass/body composition, and quality of life in adult patients (aged 16 and over) with single-chamber hearts.
The study may ultimately lead to improved interventions and exercise recommendations that promote an active lifestyle and enhance health, circulation, and physical function in patients with single-chamber hearts.
- Conditions
- Fontan Circulation
- Keywords
- Skeletal muscle, Fontan patients, Congenital heart disease, muscle function
- Medical subject headings
- Heart Defects, Congenital
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
| Study group | Role | What they receive |
|---|---|---|
| Patients | Not described | |
| Controls | Not described |
What is being measured
The primary outcome is the main question the study is designed to answer.
Relationship between anterior thigh muscle volume and peak maximal oxygen uptake in patients vs. controls
Muscle volume is measured in litres using magnetic resonance imaging. VO2peak is measured in L/min and ml/kg/min using cardiopulmonary exercise testing with breath-by-breath gas analyzers.
Measured: Baseline visit (single time-point)
Relationship between knee extension muscle strength and peak maximal oxygen uptake in patients vs. controls
Muscle strength (isometric peak torque) is measured in Nm using Biodex. VO2peak is measured in L/min and ml/kg/min using cardiopulmonary exercise testing with breath-by-breath gas analyzers.
Measured: Baseline visit (single time-point)
Secondary outcomes (5)
Anterior thigh muscle fat infiltration in patients vs. controls
Measured in % using magnetic resonance imaging.
Measured: Baseline visit (single time-point).
Whole body muscle composition in patients vs. controls
Measured in L and/or per kg body mass using magnetic resonance imaging
Measured: Baseline visit (single time-point)
Quality of life in patients vs. controls and its relationship to muscle function
Quality of life aspects are measured using surveys (SF-36).
Measured: Baseline visit (single time-point visit)
Cardiac function in patients vs. controls
Ventricular end-diastolic volume, Ventricular end-systolic volume, and Stroke volume measured in ml/m²
Measured: Baseline visit (single time-point)
Whole body fat composition in patients vs. controls
Measured in L and/or per kg body mass using magnetic resonance imaging
Measured: Baseline visit (single time-point)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted19 Feb 2026
- Study start18 Feb 2026
- Primary completion8 Jun 2026
- Study completion8 Jun 2026
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Fontan CirculationStudies of the same condition, open and under way.
- More trials run by Karolinska InstitutetThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Cross-sectional
- Enrolment
- 34 participants (actual)
Sponsor and investigators
- Lead sponsor
- Karolinska Institutet
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Tommy Lundberg, Karolinska Institutet
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07420660
- Sponsor's protocol ID
- 2024-07444-01
- Acronym
- Muscle in TCPC
- Status last verified
- Aug 2026
- First submitted
- 28 Jan 2026
- Last updated
- 7 Aug 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: The select population in the Stockholm area is too small for this. There is a clear risk that individual patients are identified.
Study at a glance
From the registry record, last updated by the sponsor on 7 Aug 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Importance of Muscle Function for Patients With Single-chamber Heart
- ClinicalTrials.gov ID
- NCT07420660
- Acronym / sponsor ID
- Muscle in TCPC / 2024-07444-01
- Conditions
- Fontan Circulation
- Keywords
- Skeletal muscle, Fontan patients, Congenital heart disease, muscle function
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 34 participants (actual)
- Lead sponsor
- Karolinska InstitutetUniversity, hospital or other
- Study start
- 18 Feb 2026 (actual)
- Primary completion
- 8 Jun 2026 (actual)
- Study completion
- 8 Jun 2026 (actual)
- First posted
- 19 Feb 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Groundbreaking cardiac surgery has significantly improved survival rates for patients with single-chamber hearts. However, despite these life-saving interventions, the long-term prognosis remains concerning, with an increased risk of heart failure, sudden cardiac death, and reduced quality of life. The absence of a chamber that pumps blood to the lungs means individuals must rely on their leg muscles to passively return blood and oxygenate the lungs. Unfortunately, studies indicate reduced muscle mass and function in these patients.
The aim is to clarify the complex interplay between single-chamber circulation and muscle function, paving the way for targeted interventions such as muscle strengthening training for this unique patient group. Our hypothesis is that muscle mass and function correlate with circulatory limitations, and that muscle strengthening training could, over time, improve both muscle and circulatory function simultaneously.
The first part of the project includes tests for maximal oxygen uptake, heart and circulatory function, muscle strength, muscle mass/body composition, and quality of life in adult patients (aged 16 and over) with single-chamber hearts.
The study may ultimately lead to improved interventions and exercise recommendations that promote an active lifestyle and enhance health, circulation, and physical function in patients with single-chamber hearts.
Study design
- Observational model
- Cohort
- Time perspective
- Cross-sectional
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Patients | – | – |
| Controls | – | – |
Who may qualify
- Ages
- 16 to 50 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child, Adult
- Study population
- Patients linked to the Region Stockholm outpatient clinic
Key inclusion criteria (5 listed)
- Diagnosis of a Fontan circulation: individuals who have undergone the Fontan procedure with only one functioning systemic ventricle, confirmed by medical records or attending physician.
- Stable clinical status: patients should be clinically stable without significant cardiovascular or renal dysfunction as determined by clinical examinations.
- Age range: 16-50 years.
- Ability to exercise: Participants must be physically able to participate in the exercise protocol according to a preliminary medical examination.
- Controls: Age and sex-matched. Healthy (no chronic diseases, assessed by health questionnaire and interview).
Key exclusion criteria (4 listed)
- Recent surgery or hospitalization: individuals who have undergone cardiovascular surgery or hospitalization within six months prior to inclusion.
- Severe functional limitations: Patients with clear functional limitations unrelated to Fontan physiology, such as musculoskeletal disorders.
- Significant comorbidities: Serious non-cardiac comorbidities that may independently affect work capacity, such as advanced pulmonary disease.
- Contraindications for exercise testing: Conditions that contraindicate physical testing, such as uncontrolled cardiac arrhythmias or severe heart failure (New York Heart Association III-IV).
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Primary outcome
Relationship between anterior thigh muscle volume and peak maximal oxygen uptake in patients vs. controls
Time frame: Baseline visit (single time-point)
Muscle volume is measured in litres using magnetic resonance imaging. VO2peak is measured in L/min and ml/kg/min using cardiopulmonary exercise testing with breath-by-breath gas analyzers.
Relationship between knee extension muscle strength and peak maximal oxygen uptake in patients vs. controls
Time frame: Baseline visit (single time-point)
Muscle strength (isometric peak torque) is measured in Nm using Biodex. VO2peak is measured in L/min and ml/kg/min using cardiopulmonary exercise testing with breath-by-breath gas analyzers.
5 secondary outcomes
Anterior thigh muscle fat infiltration in patients vs. controls
Time frame: Baseline visit (single time-point).
Whole body muscle composition in patients vs. controls
Time frame: Baseline visit (single time-point)
Quality of life in patients vs. controls and its relationship to muscle function
Time frame: Baseline visit (single time-point visit)
Cardiac function in patients vs. controls
Time frame: Baseline visit (single time-point)
Whole body fat composition in patients vs. controls
Time frame: Baseline visit (single time-point)
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 7 Aug 2026.
- Individual participant dataSharing planned: No. The select population in the Stockholm area is too small for this. There is a clear risk that individual patients are identified.
Related trials for Fontan Circulation
Not yet recruitingObservational study
A Simple Method for Monitoring the End-organ Function in Patients With Fontan Circulation.
Fontan Procedure, Fontan Circulation
Enrolling by invitation
Feasibility of Non-invasive Hemodynamic Assessment by 5D Flow in Congenital Heart Disease
Pulmonary Hypertension, Right Ventricular Outflow Tract Dysfunction
Recruiting
Venous Compression in Fontan
Single-ventricle, Fontan Circulation
RecruitingPhase 2
CAMEO-FONTAN -Dapagliflozin in the Failing Fontan Circulation
Fontan Circulation, Single Ventricle Heart Disease
Not yet recruitingObservational study
Occlutech AFR Fontan Study
Failure of Fontan Type Circulation, Fenestration
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Fontan Circulation, run by Karolinska Institutet at 1 site in Sweden.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 4 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 7 Aug 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Sweden. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Relationship between anterior thigh muscle volume and peak maximal oxygen uptake in patients vs. controls (time frame: Baseline visit (single time-point)). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 7 Aug 2026; AzTrials last refreshed its copy on 27 Oct 2026.