Masking of Pressure Overload in a Patient with Pulmonary Thromboembolism Accompanied by Atrial Septal Aneurysm

A pulmonary thromboembolism (PTE) causes a dramatic pressure overload to the right heart. Previous case reports have shown that elevated right atrial pressure secondary to a PTE can cause right-to-left shunting in the presence of an atrial septal aneurysm (ASA). A 57-year-old female with diabetes, hypertension, and an old cerebral infarction was admitted to our hospital with acute PTE. Initial transthoracic echocardiography (TTE) showed an ASA swing from the right side to the left side, and right-to-left shunting was detected immediately in the agitated saline test. However, definite signs of pressure overload of the right heart were not detected in the TTE. This educational case shows that right-to-left shunting via a patent foramen ovale in the ASA can cause normal right atrial pressure, thus masking the pressure overload of the right heart in a patient with PTE.