Impaired Exercise Capacity following Atrial Septal Defect Closure: An Invasive Study of the Right Heart and Pulmonary Circulation

Abstract

Patients with early repair of an isolated atrial septal defect (ASD) are expected to have unremarkable right ventricular (RV) and pulmonary circulation physiology. Some studies, however, suggest persistent functional impairment. We aimed to examine the role of abnormal RV and pulmonary vascular response to exercise in patients who had undergone ASD closure. Using a previously published data set, we reviewed invasive exercise cardiopulmonary testing with right-sided hemodynamic data for 12 asymptomatic patients who had undergone ASD closure. The 5 (42%) patients with impaired maximal oxygen uptake (V : o 2max ) were older and exhibited a lower peak cardiac index (5.6 AE 0.8 vs. 9.0 AE 1.2 L/min/m 2 ; P ¼ .005) because of abnormal stroke volume augmentation (þ3.2 AE 3.9 vs. þ17.4 AE 10.2 mL/m 2 ; P ¼ .02). While all resting hemodynamic variables were similar, patients with low V :o 2max tended to have abnormal total pulmonary vascular resistance change during exercise (þ11% AE 41% vs. −28% AE 26%; P ¼ .06) and had a steeper relation between mean pulmonary arterial pressure and cardiac index (5.8 AE 0.6 vs. 2.2 AE 0.1 L/min/m 2 ; P ¼ .02). The increase in peak mean RV power during exercise was also significantly lower in the impaired-V: o 2max patients (4.7 AE 1.6 vs. 7.6 AE 2.1 J/s; P ¼ .04). As described in the original study, despite normal resting hemodynamics, a subset of asymptomatic patients with repaired ASD had diminished exercise capacity. Our analysis allows us to conclude that this is due to a combination of abnormal pulmonary vascular response to exercise and impaired RV function.

Clinical Evaluation and Management of Pulmonary Hypertension in the Adult With Congenital Heart Disease

“…Even in patients with excellent long-term prognosis, subtle pulmonary vascular remodeling of both large and small vessels may persist after the repair of a shunt lesion 25,26 ; this is associated with lower exercise capacity, but the prognostic significance is unknown.…”

“…66 A subset of patients may also have subclinical residual right heart and pulmonary vascular dysfunction that limits RV stroke volume augmentation during exercise after ASD closure. 26,[68][69][70] Clinical decision making is more difficult for patients with evidence for mild or moderate pulmonary vascular disease (eg, intermediately elevated PVR), because a subset will develop PAH after closure, and it is preferable not to perform closure in that group. One study reported that most patients who developed PAH late after ASD or ventricular septal defect closure had baseline PVR>5 Wood units (n=18/22), PVR:SVR>0.33 (n=21/22), or Q p :Q s <1.5 (n=11/22).…”

Changes in blood volume shunting in patients with atrial septal defects: assessment of heart function with cardiovascular magnetic resonance during dobutamine stress

“…Exercise capacity is often used as a marker of the impact of the ASD because it is quantitative and less prone to bias compared with reported symptoms. Several studies have found improved exercise capacity after surgical or transcatheter closure of the ASD, 11 – 16 even though impaired results have also been described in a subset of patients. 16 The relationship between exercise capacity and the size of the defect or the degree of shunting (QP/QS) is not straightforward.…”

Biventricular contractility during exercise in adults with small, unrepaired atrial septal defects

“…A small ASD should like a ventricular septal defect with similar AV‐shunting potentially induce the same changes by triggering endothelial re‐modulation in the pulmonary vascular wall which results in vessel hypertrophy, stiffness, and ultimately increasing vascular resistance. This could explain why patients with repaired ASD demonstrated abnormal pulmonary vascular and right ventricular response to exercise, with these abnormalities being associated with reduced functional capacity …”