Abnormal ventilatory response to exercise in young adults operated for ventricular septal defect in early childhood: A long-term follow-up

BackgroundVentricular septal defects (VSDs) are normally closed in early childhood, and postsurgical physical capacity is generally considered normal. Despite an increasing understanding of late cardiac morbidity among these patients, long-term pulmonary function remains to be investigated. Therefore, the aim of this prospective follow-up study was to describe ventilatory function during exercise in VSD-repaired adults operated in early life.MethodsWe tested cardiopulmonary exercise capacity in 27 patients and 30 healthy control subjects on an ergometer cycle. Each test was preceded by a standard spirometry, and the exercise test was performed as a maximal incremental test. Pulmonary ventilation and gas exchange were simultaneously measured breath-by-breath with minute ventilation at peak exercise as our main endpoint.ResultsIn the VSD-group the median surgical age was 1.9 (95% CI 1.1-2.8 years) and the mean age at time of examination was 21.1 ± 3.1 years in the VSD-group vs. 21.2 ± 2.5 years in the control group. Mean minute ventilation at peak exercise was significantly lower in the VSD-group compared with the controls: 1.4 ± 0.4 L/kg/min vs. 1.8 ± 0.4 L/kg/min, p < 0.01. Likewise, mean oxygen uptake was reduced: 38.0 ± 8.2 ml/kg/min in the VSD-cohort vs. 47.9 ± 6.5 ml/kg/min among controls, p < 0.01. In terms of breath rate and ventilatory equivalents (O2 and CO2) there were no differences between the groups.ConclusionsPatients with a surgically closed VSD have a markedly abnormal ventilatory response to exercise with significantly reduced minute ventilation despite a similar breath rate. With a follow-up of almost two decades our finding most certainly reflects an unknown but persisting abnormality.