• Paediatric Cardiology
• exercise testing
• lung physiology

Exercise capacity is reduced across the spectrum of patients with congenital heart disease (CHD), both in natural history and after surgical and interventional treatment.1

In over three decades of investigation into the mechanisms of reduced exercise tolerance in CHD, interest initially focused on the role of cardiac factors, abnormal lung physiology and cardiopulmonary interactions.2 3

However, based on the recognition that adults with CHD can have a heart failure (HF) syndrome, which completely overlaps with that of adults with acquired heart disease,4 ‘peripheral factors’ like neuro-humoural activation, stimulation from peripheral receptors, vascular function and skeletal muscle function and haemodynamics have recently attracted growing interest.4 5

In their paper published in this issue of Heart, Greutmann and colleagues from Toronto shift the focus onto respiratory muscle function (see page 1164).6 They observed that adults with several forms of CHD have reduced respiratory muscle and skeletal muscle strength and that reduced respiratory muscle strength (RMS) is associated with reduced exercise capacity. They also observed that reduced RMS might cause an overestimation of the degree of lung impairment in adults with CHD, because measurement of forced expired volume and vital capacity depends on RMS, which is reduced.

The findings of this study are in line with those of studies in …