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

BACKGROUND: Ventricular 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.

METHODS: We 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.

RESULTS: In the VSD-group the median surgical age was 1.9 (95% CI 1.1-2.8years) and the mean age at time of examination was 21.1±3.1years in the VSD-group vs. 21.2±2.5years in the control group. Mean minute ventilation at peak exercise was significantly lower in the VSD-group compared with the controls: 1.4±0.4L/kg/min vs. 1.8±0.4L/kg/min, p<0.01. Likewise, mean oxygen uptake was reduced: 38.0±8.2ml/kg/min in the VSD-cohort vs. 47.9±6.5ml/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.

CONCLUSIONS: Patients 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.