EUROECHO edition:14 location:Copenhagen date:8-11 Dec 2010
Background: The development of shunt-induced pulmonary vascular lesions may affect exercise capacity in patients with atrial septal defect (ASD) type secundum. We hypothesized that pulmonary vascular resistance (PVR) as measured by bicycle stress echocardiography is an important determinant of exercise capacity in patients with ASD.
Methods: Eighteen patients with open (mean age 39.2±18.5 years) and 28 patients with closed ASD (mean age 41.1±16.6 years) underwent standard and symptom-limited bicycle stress echocardiography. Peak oxygen consumption (peak vO2) was measured using cardiopulmonary exercise testing. Change from rest to peak exercise in cardiac output (CO) and pulmonary artery pressures (PAP) were measured. PVR was calculated as the ratio of change PAP to change in CO. Uni- and multivariate linear regression analysis were performed.
Results: Peak vO2 in patients with open (79±19; %predicted; P<0.0001) and closed ASD (88±18; %predicted; P<0.0001)was lower than average. Change in CO was not statistically different (6.6±3.7 versus 6.2±2.7; L/min; P=0.697), whereas change in PAP (37.0±16.5 versus 20.9±7.4; mmHg; P<0.0001) and PVR (5.6±2.4 versus 3.8±1.9; mmHg/L/min; P=0.017) were higher in patients with open ASD when compared to patients with closed ASD. According to multivariate analysis, body mass index (P=0.001) and PVR (P=0.01) were independent determinants of peak vO2 in patients with open ASD, whereas gender (P=0.025), left ventricular ejection fraction (P=0.025) and PVR (P=0.049) were independent determinants of peak vO2 in patients with closed ASD.
Conclusions: Both in patients with open and closed ASD, PVR is an important and possibly limiting determinant of exercise capacity. Whether lowering PVR improves exercise capacity requires further investigation.