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 1.1-2.8 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.

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.