Influence of venous access site and right atrial anatomical variants on the detection of patent foramen ovale during agitated saline contrast transesophageal echocardiography

Abstract

Background: Contrast-enhanced transesophageal echocardiography (cTEE) is the gold standard for the detection of patent foramen ovale (PFO). However, the diagnostic yield may vary depending on the venous injection site of the saline contrast medium and the presence of anatomical variants such as the Eustachian valve (EV) or Chiari network (CN), which can alter right atrial flow dynamics. This study aims to evaluate whether the route of injection—an upper-extremity vein vs. a lower-extremity vein—affects PFO detection and whether the presence of EV or CN further influences shunt visualization. Methods: We prospectively enrolled 174 patients referred for cTEE for suspected cardioembolic etiology. Agitated saline contrast was injected via an upper-extremity vein (brachial/antecubital vein; UEV) and via a lower-extremity vein (saphenous veins; LEV) during standardized Valsalva maneuver. Each route was tested with up to three adequately performed injections irrespective of the alternate-route result. PFO was defined as microbubbles visualized traversing the interatrial septum within the first five cardiac cycles after right atrial opacification and Valsalva release. EV/CN was recorded. EV length and mobility and atrial septal aneurysm (ASA) were assessed by re-review of archived TEE images. Results: PFO was detected in 73/174 (42.0%) by either route. UEV was positive in 58/174 (33.3%) and LEV in 64/174 (36.8%) (p = 0.307). Among PFO-positive patients, 49 (67.1%) were positive with both routes, 9 (12.3%) only with UEV injection, and 15 (20.5%) only with LEV injection. EV was present in 56/174 (32.2%) and CN in 4/174 (2.3%); among PFO-positive patients, EV was present in 31/73 (42.5%) and CN in 2/73 (2.7%). In EV-positive PFO patients (n = 31), positive LEV injection detected 31/31 (100%) whereas positive UEV injection detected 17/31 (54.8%) (p = 0.000122). LEV-only positivity occurred in 9/11 patients with EV length ≥10 mm versus 5/20 with EV length <10 mm (OR 13.5, p = 0.0068). Conclusion: LEV injection improves detection in EV-positive patients, supporting an anatomy-guided approach in which LEV injection is added when EV is visualized or when UEV injections are inconclusive. Clinical Trial Number: Not applicable. © 2026 Wiley Periodicals LLC.