{"id":"https://openalex.org/G3544729136","display_name":"Functional muscle characteristics and cardio-respiratory interaction in patients with Fontan palliation","description":"Background: Congenital heart disease (CHD) is the most common congenital defect, affecting about 1% of newborns. Advances in cardiology care, particularly the advent of open heart surgery has substantially improved survival over the last few decades. Survival to adulthood is now expected even for patients with lesions of moderate and great complexity. Among adults with complex CHD, the cohort of survivors after the Fontan-palliation for univentricular physiology is the most rapidly growing. Given their unique physiology without a pumping chamber supporting the pulmonary circulation, their exercise capacity as adults is often severely reduced. In advanced stages of failure, heart transplantation is the only viable treatment option for many of these patients. However, donor organs are scarce and all efforts must be made to improve outcomes and delay the need for transplantation or circulatory support. The underlying mechanisms of impaired exercise capacity in Fontan-patients are, however, not fully understood. Studies have suggested that exercise limitations are secondary to cardiac defects, factors related to cardiac surgery, chronotropic incompetence and underlying lung disease but these variables alone do not fully explain the exercise limitations found in this young population. In a substantial part of these patients, weakness of respiratory and skeletal muscles was demonstrated and data suggest that weak respiratory muscles are more related to impaired peak oxygen consumption (VO2peak) than weak skeletal muscles. However, muscle dysfunction was not yet assessed objectively, i.e. by ,measurement of muscle contractility in response to nerve stimulation and assessing proneness of muscles to fatigue. Exercise training is often suggested but due to the lack of detailled knowledge, advice for specific training regimes is difficult. Specific respiratory muscle training (RMT) proved beneficial in patients with acquired heart failure, even as an adjunct to exercise training, but safety was not assessed in CHD patients. This is of particular importance in Fontan-patients as their physiology is unique and passive pulmonary blood flow may be affected by different RMT-protocols. Aim: The aim of the present investigation in adults after the Fontan-palliation is therefore threefold: i) to objectively assess respiratory and leg muscle contractility, i.e. strength, and proneness of these muscles to fatigue under maximal and submaximal conditions; ii) to assess the hemodynamic response to respiratory challenges similar to those used for RMT;  iii) to assess the safety of RMT challenges. We hypothesise a) that both respiratory and leg muscles are weak in some but not all patients, b) that respiratory and leg muscles are more prone to fatigue than those of controls, even in subjects without weak leg muscles, c) that RMT-like respiratory work does compromise haemodynamics more when the inspiratory load is sustained for = 50% of the breathing cycle and if expiration is unloaded and that this effect is larger in patients than in matched controls. Methods: 20 patients with Fontan palliation and 20 matched controls will undergo a maximal incremental cycling (VO2peak) test and an endurance exercise test while both inspiratory muscle and quadriceps muscle contractility and fatigue will be assessed concomittantly with respiratory and hemodynamic responses. On another day, both groups will perform respiratory loaded breathing with different in- and expiratory loads, similar to those used for RMT, while hemodynamics will be assessed. Expected impact: Results of this study will render, for the first time, objective data on respiratory and leg muscle weakness and fatigability in CHD patients after Fontan-palliation. In addition, it will provide hemodynamic data with RMT-like loaded breathing and thus the urgently needed information on safety of respiratory muscle training in these patients. This combined information will provide the necessary and urgently awaited basic information for specifically tailored and most efficient training programs for this emerging group of complex adult patients.","funder_award_id":"146481","funder":{"id":"https://openalex.org/F4320320924","display_name":"Schweizerischer Nationalfonds zur F\u00f6rderung der Wissenschaftlichen Forschung","doi":"10.13039/501100001711"},"funded_outputs":["https://openalex.org/W4304690774","https://openalex.org/W7204532009"],"funded_outputs_count":2,"parent_awards":[],"sub_awards":[],"sub_awards_count":0,"amount":162780.0,"currency":"CHF","amount_usd":178581.96,"amount_usd_basis":"daily_rate","recipients":[{"id":"https://openalex.org/I35440088","display_name":"ETH Zurich","ror":"https://ror.org/05a28rw58","country_code":"CH","roles":["lead"],"share":null,"basis":"affiliation_matcher","asserted_by":"funder"}],"recipient_countries":[{"country_code":"CH","share":1.0,"amount_usd":178581.96,"basis":"organisation_location"}],"recipient_regions":[],"research_scope":{"is_research":true,"basis":"funder_default","tier":1},"funding_type":"research","funder_scheme":"Project funding","start_date":"2013-11-01","end_date":"2016-10-31","start_year":2013,"end_year":2016,"landing_page_url":"https://data.snf.ch/grants/grant/146481","doi":null,"provenance":"snsf","lead_investigator":{"given_name":"Spengler,","family_name":"Christina","orcid":null,"role_start":null,"affiliation":{"name":"ETH Zurich \u2013 ETHZ","country":"Switzerland","ids":null}},"co_lead_investigator":null,"investigators":null,"works_api_url":"https://api.openalex.org/works?filter=awards.id:G3544729136","primary_topic":{"id":"https://openalex.org/T10300","display_name":"Congenital Heart Disease Studies","score":0.9767,"subfield":{"id":"https://openalex.org/subfields/2705","display_name":"Cardiology and Cardiovascular Medicine"},"field":{"id":"https://openalex.org/fields/27","display_name":"Medicine"},"domain":{"id":"https://openalex.org/domains/4","display_name":"Health Sciences"}},"topics":[{"id":"https://openalex.org/T10300","display_name":"Congenital Heart Disease Studies","score":0.9767,"subfield":{"id":"https://openalex.org/subfields/2705","display_name":"Cardiology and Cardiovascular Medicine"},"field":{"id":"https://openalex.org/fields/27","display_name":"Medicine"},"domain":{"id":"https://openalex.org/domains/4","display_name":"Health Sciences"}}],"institution_awarded":[{"id":"https://openalex.org/I35440088","display_name":"ETH Zurich","ror":"https://ror.org/05a28rw58","country_code":"CH","type":"education","lineage":["https://openalex.org/I2799323385","https://openalex.org/I35440088"]}],"updated_date":"2026-11-09T03:09:34.000Z","created_date":"2026-07-13T04:27:35.000Z"}