Evaluation of Exercise Capacity with Cardiopulmonary Exercise Testing and Type B Natriuretic Peptide Concentrations in Adult Patients with Patent Atrial Septal Defect

Abstract

Adults with patent atrial septal defect (ASD) usually find their exercise capacity satisfactory, and therefore hesitate to accept proposed surgical treatment of the heart disease. The aim of our study was to evaluate both the exercise capacity, using the cardio-pulmonary stress test, and brain natriuretic peptide (BNP) levels in asymptomatic adults with ASD. Thirty-six patients with patent secundum type ASD (aged mean 44.7 ± 8.2 years) were studied. The control group consisted of 25 healthy subjects at the mean age of 45.6 ± 6.1 years. Echocardiography and CPST were performed and BNP levels measured in all subjects. Oxygen uptake (VO_{2 max}) was lower in ASD patients than in controls (22.1 ± 5.6 vs. 30.0 ± 6.8 ml/kg/min, p = 0.00001); the VE/VO₂ slope was elevated in ASD patients compared with healthy subjects (31.3 ± 6.6 vs. 26.9 ± 3.3, p = 0.001), and exceeded 34 in 5 patients. VO_{2 max} showed a negative correlation with the pulmonary to systemic flow ratio Qp:Qs (r = –0.46, p = 0.004), and a positive correlation was found between the VE/VO₂ slope and Qp:Qs (r = 0.32, p = 0.05). BNP levels were higher in the ASD group than in the controls (60.6 ± 49.9 vs. 32.6 ± 24.5 pg/ml, p = 0.02). BNP correlated positively with RV diameter and Qp:Qs (r = 0.38 and 0.39 respectively, p = 0.03) and negatively with maximum VO₂ (r = –0.5, p = 0.004) and VO₂% (r = –0.32, p = 0.07). Conclusions: Although most adult patients with ASD perceive their exercise capacity as satisfactory, objective assessment reveals that in fact it is significantly decreased. BNP levels are increased comparing to healthy individuals. Decreased exercise capacity and increased BNP levels seem to result from right ventricular volume overload.

The role for cardiopulmonary exercise testing in patients with atrial septal defects: A review

“…However the degree of these resting abnormalities does not always correspond to the degree of interference with exercise capacity as shown by objective measurements such as peak oxygen uptake [34][35][36][37]. The same is found with the pulmonary to systemic flow ratio, Qp:Qs, which correlates to peak VO 2 pre-closure in three studies [30,31,36] but not in three others [38,29,32].…”

“…Hence, even patients who describe themselves as asymptomatic turn out to have an objective exercise capacity more than 25% below normal [30,31] with peak VO 2 lowest in patients with symptoms compared to those without [32]. Other CPET parameters involving gas exchange efficiency and the anaerobic threshold are also impaired in patients with ASD [29,30].…”

“…Hence, even patients who describe themselves as asymptomatic turn out to have an objective exercise capacity more than 25% below normal [30,31] with peak VO 2 lowest in patients with symptoms compared to those without [32]. Other CPET parameters involving gas exchange efficiency and the anaerobic threshold are also impaired in patients with ASD [29,30]. There have been no systematic studies utilising serial CPET on patients with ASD managed conservatively, however it was established in an early cross-sectional study that symptoms usually develop during adulthood and older patients were more frequently disabled by symptoms suggesting the natural time course is far from benign [33].…”

Exercise performance and quality of life is more impaired in Eisenmenger syndrome than in complex cyanotic congenital heart disease with pulmonary stenosis

“…[2,3,7,14,15] Diller et al showed that peak VȮ 2 is a powerful predictor of mortality in patients with congenital heart disease [2]. A peak VȮ 2 of 15.5 ml/kg/min was a predictor for mortality in that group combining several congenital defects.…”

“…At exercise, when systemic vascular resistance drops, pulmonary blood flow decreases resulting in severe cyanosis. Exercise capacity displayed in a reduced peak oxygen uptake (peak V O 2 ) and ventilatory inefficiency estimated from the steepness of the VĖ/VĊ O 2 slope is the worst seen in the cohort of patients with congenital heart disease [2][3][4].…”