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Heart 99:1530-1534 doi:10.1136/heartjnl-2013-304249
  • Congenital heart disease
  • Original article

Skeletal muscle abnormalities and exercise capacity in adults with a Fontan circulation

  1. David S Celermajer1,2
  1. 1Department of Cardiology, Royal Prince Alfred Hospital, Sydney, New South Wales, Australia
  2. 2Department of Medicine, Sydney Medical School, Sydney, New South Wales, Australia
  3. 3School of Medicine, Deakin University, Geelong, Victoria, Australia
  4. 4Department of Medicine, NorthWest Academic Centre, The University of Melbourne, St Albans, Victoria, Australia
  5. 5Neuroscience Research Australia, Sydney, New South Wales, Australia
  6. 6Departments of Musculoskeletal Biology and Magnetic Resonance and Image Analysis Research Centre, University of Liverpool, Liverpool, UK
  1. Correspondence to Dr Rachael L Cordina, GUCH Department, The Heart Hospital, 16-18 Westmoreland St, London W1G 8PH, UK; Rachael.Cordina{at}uclh.nhs.uk
  • Received 7 May 2013
  • Revised 7 June 2013
  • Accepted 18 June 2013
  • Published Online First 11 July 2013

Abstract

Objectives The peripheral muscle pump is key in promoting cardiac filling during exercise, especially in subjects who lack a subpulmonary ventricle (the Fontan circulation). A muscle-wasting syndrome exists in acquired heart failure but has not been assessed in Fontan subjects. We sought to investigate whether adults with the Fontan circulation exhibit reduced skeletal muscle mass and/or metabolic abnormalities.

Design and patients Sixteen New York Heart Association Class I/II Fontan adults (30±2 years) underwent cardiopulmonary exercise testing and lean mass quantification with dual x-ray absorptiometry (DXA); eight had calf muscle 31P magnetic resonance spectroscopy as did eight healthy age-matched and sex-matched controls. DXA results were compared with Australian reference data.

Setting Single tertiary referral centre.

Results Peak VO2 was 1.9±0.1 L/min (66±3% of predicted values). Skeletal muscle mass assessed by relative appendicular lean mass index was significantly reduced compared with age-matched and sex-matched reference values (Z-score −1.46±0.22, p<0.0001). Low skeletal muscle mass correlated with poorer VO2 max (r=0.67, p=0.004). Overall, skeletal muscle mass T-score (derived from comparison with young normal reference mean) was −1.47±0.21; 4/16 Fontan subjects had sarcopenic range muscle wasting (T-score <−2.0) and 9/16 had less marked, but clinically significant wasting (T-score <−1.0 but ≥−2.0). Muscle aerobic capacity, measured by the rate constant (k) of postexercise phosphocreatine resynthesis, was significantly impaired in Fontan adults versus controls (1.48±0.13 vs 2.40±0.33 min−1, p=0.02).

Conclusions Fontan adults have reduced skeletal muscle mass and intrinsic muscle metabolic abnormalities.

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