Challenging Diagnosis of Patent Foramen Ovale in Presence of a Large Eustachian Valve

We report the case of a 39-year-old woman who presented with cryptogenic stroke. Conventional and contrast echocardiography modalities noticed a large Eustachian valve (EV) but failed to identify any right-to-left shunt. Conversely, contrast-transcranial Doppler revealed a grade 3 right-to-left shunt. Contrast echocardiography was repeated with bubble injections through both an upper extremity and a femoral vein, 10 min apart from each other. While no shunt was observed following upper extremity injection, >20 bubbles crossed the inter-atrial septum when contrast was injected via femoral vein confirming the diagnosis of patent foramen ovale.