The Impact of an Atrial Septal Defect on Hemodynamics in Patients With Heart Failure

In patients with left ventricular (LV) dysfunction, a large atrial septal defect (ASD) provides an alternate pathway for left atrial emptying and prevents abnormal elevation of left atrial and LV filling pressures. In such patients, closure of the ASD can cause an increase in LV diastolic pressure with pulmonary venous hypertension and congestion. The protective effect of an ASD is attenuated or abolished in the presence of right ventricular (RV) dysfunction. Thus, an elevated LV diastolic pressure in the presence of an ASD indicates dysfunction or failure of both ventricles. In this situation, pharmacologic or mechanical unloading of the left ventricle may result in right to left shunting with arterial hypoxemia. In the absence of RV failure, creation of an ASD can reduce LV filling pressures. Management of patients with heart failure and an ASD requires accurate assessment of atrial pressures and shunt flows as well as consideration of the functional state of both ventricles.