The aim of the study was to evaluate cardiopulmonary exercise capacity (WTS) in adult patients with atrial septal defect (ASD). After excluding 10 patients with additional cardiac, pulmonary or muscle diseases, 53 patients with ASD (Gr-ASD; mean age 37.8 +/- 14.9 years; 35 women, 19 men) were enrolled in our study. In addition, we evaluated 22 healthy age and gender matched control subjects (Gr-K; mean age 36.6 +/- 14.9 years; 13 women, 9 men). First, all subjects underwent resting spirometry and forced vital capacity--(FVC; % of predicted value), one-second forced expiratory volume--(FEV1; % of predicted value) and FEV1/FVC (%) were determined. Then each subject performed a symptom-limited, incremental exercise test (modo Bruce). We evaluated the following parameters of resting metabolism: respiratory rate--(RR; L/min), minute ventilation--(VE; L/min), tidal volume--(Vt; L), oxygen uptake--(VO2; ml/kg/min), end-tidal carbon dioxide pressure--(PET CO2; mmHg), end tidal oxygen pressure--(PET O2; mmHg), ventilatory equivalent for carbon dioxide--(VE/VCO2) and ventilatory equivalent for oxygen--(VE/VO2). The following exercise parameters were analysed: peak oxygen uptake--(VO2 peak; ml/kg/min), VO2 peak expressed as % of predicted value--(VO2 %N), anaerobic threshold--(AT; % VO2 max), ventilatory equivalent for carbon dioxide--(VE/VCO2), end-tidal carbon dioxide pressure--(PET CO2; mmHg), O2 pulse, time of exercise--(T; min) and time to AT--(TAT; min). In addition, we performed a subgroup analysis for ASD patients below and > or = 40 years of age. All values were expressed as mean +/- SD.
Results: Although there was no significant difference in FVC, FEV1, FEV1/FVC, VO2, VE, Vt, RR between ASD patients and controls, the ASD patients aged 40 or older showed significantly lower FEV1/FVC and significantly higher RR. Expiratory gas exchange analysis showed significant differences between the ASD patients and controls (higher VE/VCO2, VE/VO2, PET CO2, and lower PET O2 respectively). Moreover, VO2 peak, VO2%N, AT, PET CO2 and O2 pulse were significantly lower while VE/VCO2 was significantly higher in ASD patients than in normal subjects. On average, VO2%N in ASD patients was only 61% of the predicted value for age and sex. Total time of exercise and time to AT were significantly shorter in ASD patients as well.
Conclusions: WTS allows appropriate evaluation of cardiopulmonary capacity in ASD patients, though the mechanisms underlying ventilatory and hemodynamic abnormalities are still not fully understood. Adult patients with ASD reveal ventilatory abnormalities with an age-related trend towards deterioration. Cardiopulmonary exercise capacity in adults with ASD is markedly reduced in comparison with healthy population and deteriorates with age. WTS complements echocardiographic and hemodynamic evaluation of patients with ASD, and is helpful in indicating patients for ASD closure and their follow up.