Detection of Patent Foramen Ovale (PFO) Using Agitated Saline Contrast Imaging: Experience with 1162 Patients and Recommendations for Echocardiography

Abstract

Background: Paradoxical shunting via a patent foramen ovale (PFO) has a recognised association with embolic events in younger patients. The use of agitated saline contrast imaging (ASCi) for detecting atrial shunting is well documented, however optimal technique is not well described. This study describes a single-centre experience of ASCi in 1162 patients. Method: A retrospective review was undertaken of 1162 consecutive transthoracic (TTx) ASCi studies, of which 195 also underwent transoesophageal (TEE) echo. ASCi shunt results were compared with colour flow imaging (CFI) and the role of provocative manoeuvres (PM) assessed. Results: 403 TTx studies (35%) had paradoxical shunting seen during ASCi. Of these, 48% were positive with PM only. There was strong agreement between TTx ASCi and reported TEE findings (99% sensitivity, 85% specificity), with six false positive and two false negative results. In hindsight, the latter were likely due to suboptimal right atrial opacification, and the former due to transpulmonary shunting. TTx CFI was found to be insensitive (47%) for the detection of a PFO compared with TTx ASCi. Conclusions: TTx ASCi is minimally invasive and highly accurate for the detection of PFO, provided PM are used. TTx CFI was found to be inaccurate for PFO screening. It is recommended that TTx ASCi should be considered the initial diagnostic tool for the detection of PFO in clinical practice. Guidelines to ensure adequate agitated saline contrast delivery have been proposed including performance of provocative manoeuvres.