A 69-year-old woman with atypical chest pain and palpitation was referred to our echocardiography laboratory for further evaluation. The patient had a history of hypertension, hyperlipidemia, and one episode of atrial fibrillation with unremarkable physical examinations and electrocardiography. Transthoracic echocardiography revealed a normal left ventricular size and systolic function (ejection fraction ≈55%) and right ventricular enlargement with normal systolic function. It also revealed an aneurysmal interatrial septum (IAS) with two left-to-right shunts through it in the color Doppler study, especially in the parasternal right ventricular inflow view, suggestive of 2 atrial septal defects (ASDs) with a QP/QS of 1.5/1 [Figure 1 and Video 1]. Transesophageal echocardiography demonstrated a secundum type ASD (diameter = 10 mm) with a left-to-right shunt and mid-right atrial obstruction (mean gradient = 2.5 mmHg) because the aneurysmal IAS narrowed the inferior vena cava inflow and resulted in a turbulent flow, simulating an additional ASD [Figure 2 and Video 2].
An aneurysmal IAS could lead to the right atrial inflow obstruction of the inferior vena cava or the obstruction of the right pulmonary vein inflow, the right ventricular inflow, or the left ventricular inflow.[1-4] In addition, the association of aneurysmal IAS and ASD with atrial fibrillation has been demonstrated.[5,6]
Our patient had a mid-right atrial obstruction due to an aneurysmal IAS, with no signs and symptoms of inferior vena cava obstruction. However, the obstruction simulated an additional ASD in the color Doppler study in transthoracic echocardiography. Therefore, when an aneurysmal IAS exists, a mid-right atrial cavity obstruction simulating an ASD should be considered in the ASD differential diagnosis.
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