• congenital heart disease
• ventilation
• exercise testing
• gas exchange

• TGA, transposition of the great arteries
• V̇_A, alveolar ventilation
• V̇D, dead space ventilation
• V̇_E, total ventilation
• VSD, ventricular septal defect

Patients with congenital heart disease can usually perform low intensity exercise as well as healthy peers, but often have difficulty in reaching maximal exercise intensity. However, formal exercise testing has repeatedly shown impaired values for cardiorespiratory exercise performance.¹ A considerable number of patients may complain of exercise intolerance and dyspnoea at heavy intensities of exercise.

The aim of this study was to assess the efficiency of the ventilatory response to exercise by means of breath by breath analysis of gas exchange. Special attention was paid to total ventilation and alveolar ventilation as the difference between these values reflects the physiological dead space ventilation (V̇D), and is used as an index of ventilatory efficiency during exercise. More specifically, we assessed how the ventilatory response during exercise was affected by the clinical result of surgery and whether this correlated with the functional status after surgery for congenital heart disease.

To study whether an inefficient ventilatory response to exercise could be related to the effect of a sternotomy, the ventilatory response to exercise in the present group of patients was compared with a group of age matched patients who had also undergone sternotomy for surgical closure of a ventricular septal defect (VSD).