Blunted peripheral blood supply and underdeveloped skeletal muscle in Fontan patients: The impact on functional capacity

Abstract Background Changes in circulatory physiology are common in Fontan patients due to suboptimal cardiac output, which may reduce the peripheral blood flow and impair the skeletal muscle. The objective of this study was to investigate the forearm blood flow (FBF), cross-sectional area (CSA) of the thigh and functional capacity in asymptomatic clinically stable patients undergoing Fontan surgery. Methods Thirty Fontan patients and 27 healthy subjects underwent venous occlusion plethysmography, magnetic resonance imaging of the thigh musculature and maximal cardiopulmonary exercise testing. Muscle sympathetic nerve activity (MSNA), norepinephrine measures, cardiovascular magnetic resonance, handgrip strength and 6-minute walk test were also performed. Results Fontan patients have blunted FBF (1.59 ± 0.33 vs 2.17 ± 0.52 mL/min/100 mL p p 2 p 2 (29.3 ± 6 vs 41.5 ± 9 mL/kg/min p p p  = 0.006] were also higher in Fontan patients. Multivariate linear regression showed FVC (β = 0.653; CI = 0.102–1.205; p  = 0.022) and stroke volume (β = 0.018; CI = 0.007–0.029; p  = 0.002) to be independently associated with reduced CSA of the thigh adjusted for body mass index. The CSA of the thigh adjusted for body mass index (β = 5.283; CI = 2.254–8.312; p  = 0.001) was independently associated with reduced peak VO 2 . Conclusion Patients with Fontan operation have underdeveloped skeletal muscle with reduced strength that is associated with suboptimal peripheral blood supply and diminished exercise capacity.