“…The contrast echocardiography showed the bi-directional shunt flow between the atria. We interpreted that the hypoxic attack was due to functional right to left shunt [1][2][3] caused by the blood aspiration by the left ventricle, which got to negative by acute preload reduction during hemodialysis. We decided to perform the surgical correction of ASD, because hypoxia was known to indicate poor prognosis of unoperated patients with ASD [4].…”