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Updated: Sep 17, 2025

Echocardiographic Evaluation of Atrial Communications before Transcatheter Closure
Published on: February 8, 2022
Atrial Septal Defect With Right-to-Left Shunt Without Pulmonary Hypertension: Diagnosis Through Multimodality Imaging
Ryusuke Sekii1, Shingo Kato2, Naoki Nakayama3
1Department of Cardiology, Yokohama Hodogaya Central Hospital, Yokohama, Japan.
Background:
Four-dimensional flow magnetic resonance imaging (MRI) enhances the evaluation of complex cardiovascular diseases. We used MRI and advanced imaging modalities to assess a right-to-left shunt through an atrial septal defect without pulmonary hypertension (PH).
Case Summary:
An 84-year-old woman with persistent hypoxemia was found to have a significant right-to-left shunt without PH. Computed tomography angiography revealed severe aortic tortuosity compressing the right atrium, likely contributing to continuous shunting. Four-dimensional flow MRI visualized the shunt and quantified a Qp/Qs ratio of 0.61, consistent with invasive measurements.
Discussion:
Unlike classic platypnea-orthodeoxia syndrome, extreme aortic tortuosity may cause persistent right-to-left shunting even in the supine position. This case highlights how age-related anatomical changes contribute to intracardiac shunting and underscores the utility of advanced imaging.
Take-Home Message:
Right-to-left shunting without PH can persist because of anatomical factors. In this case, a correct diagnosis was obtained through comprehensive imaging, including 4-dimensional flow MRI.
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