A Blind Spot In The Heart: Eustachian Valve Complicating Atrial Septal Defect Closure

Abstract

Background and purpose: The Eustachian valve (EV) is a remnant of fetal circulation that directs inferior vena caval blood toward the foramen ovale. Persistence of a prominent EV in adulthood may alter intracardiac flow dynamics, potentially facilitating right-to-left shunting in the presence of an atrial septal defect (ASD) or patent foramen ovale (PFO), and thus contributing to hypoxemia.

Methods: A 10-year-old female with a known secundum ASD presented with a six-month history of exertional dyspnea and fatigue. Physical examination revealed an oxygen saturation of 87% on room air. ECG and chest X-ray were unremarkable. Transthoracic echocardiography (TTE) demonstrated a 14 mm ASD with preserved biventricular function. A transesophageal echocardiography (TEE)-guided percutaneous closure was planned; however, the patient developed significant desaturation and hemodynamic instability during the procedure, prompting its abortion. Subsequent TEE revealed an 18 mm ASD with a prominent EV producing bidirectional shunting.

Results: A repeat closure via the right internal jugular vein was undertaken using a 20 mm Amplatzer device. Post-procedure, oxygen saturation improved from 84% to 96%, indicating effective shunt elimination.

Conclusion: While transcatheter ASD closure is typically safe, unrecognized EV can pose procedural challenges and precipitate desaturation events. In this case, guidewire entrapment by the EV likely caused transient inferior vena cava obstruction and right-to-left shunting. Therefore, in patients presenting with unexplained hypoxemia or atypical shunting patterns, pre-procedural TEE assessment is essential to identify EV or other anatomical variants, ensuring safe and successful intervention.