State-of-the-Art Review
Pearls and Pitfalls in the Transesophageal Echocardiographic Diagnosis of Patent Foramen Ovale

https://doi.org/10.1016/j.echo.2023.05.004Get rights and content

Highlights

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    TTE with contrast study is being used for indirect diagnosis of PFO.

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    TEE affords direct visualization of PFO with measurement of PFO size.

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    TEE also provides detailed anatomical features to define a high-risk PFO.

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    TEE is a useful screening test for patients with cryptogenic stroke.

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    Echo specialists with competent TEE skill should be members of the heart-brain team.

Large randomized controlled trials have shown the benefits of percutaneous closure of patent foramen ovale (PFO) in patients with cryptogenic stroke and PFO. Recent studies have highlighted the clinical significance and prognostic implication of various anatomical features of PFO and the adjacent atrial septum, such as atrial septal aneurysm (ASA), PFO size, large shunt, and hypermobility. Transthoracic echocardiography with contrast study is used for the indirect diagnosis of PFO, as it reveals the passage of the contrast into the left atrium. In contrast, transesophageal echocardiography (TEE) offers a direct demonstration of PFO by measuring its size using the maximum separation distance between the septum primum and septum secundum. Furthermore, TEE enables the acquisition of detailed anatomical features of the adjacent atrial septum including ASA, hypermobility, and PFO tunnel length, which carry significant prognostic implications. Transesophageal echocardiography also facilitates the diagnosis of pulmonary arteriovenous malformation, a relatively rare cause of paradoxical embolism. This review provides evidence for supporting TEE as a useful screening test for patients with cryptogenic stroke to identify suitable candidates for percutaneous device closure of PFO. Additionally, cardiac imaging specialists with proficiency in comprehensive TEE examination should be part of the heart-brain team for proper evaluation of and decision-making in patients with cryptogenic stroke.

Central Illustration

Algorithm for the echocardiographic diagnosis of the PFO during evaluation of patients with embolic stroke of unknown source (ESUS). DDx, Differential diagnosis; TCD, transcranial Doppler; +, positive test for the presence of right-to-left shunt; −, negative test for the presence of right-to-left shunt.

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Section snippets

Transthoracic Echocardiography

In rare cases, a small right-to-left shunt flow across a PFO can be detected on color Doppler flow mapping (Supplemental Figure 1A and B). Unlike an atrial septal defect, which is a fixed opening in the atrial septum that allows the bidirectional passage of blood between the atria, flow across a PFO is more typically functional and depends on the relative pressure between the 2 atria.25 Therefore, most cases require an intravenous injection of hand-agitated saline with a Valsalva maneuver for

Direct Diagnosis of PFO

The main advantage of TEE is its high resolution, which contributes to a better and more direct diagnosis of PFO. During TTE, the passage of contrast bubbles into the left atrium is used as indirect evidence of PFO. In contrast, TEE allows direct visualization of PFO with a separation of the septum primum and the secundum. Shunt across a PFO shown during TEE is quite variable without a Valsalva maneuver, and right-to-left shunt on conventional color Doppler flow mapping may be either small (

Conclusion

Over the past decade, there has been a paradigm shift in the management of cryptogenic stroke with PFO. Randomized controlled trials have shown increasing evidence supporting the beneficial effect of percutaneous device closure of the PFO. The heterogeneity of treatment effects can be well explained by the classification system that includes anatomical features of a high-risk PFO. Traditionally, stroke physicians or neurologists used the RoPE score to evaluate the relative risk reduction of

Acknowledgments

I thank Dr. Joon Seo Lim from the Scientific Publications Team at Asan Medical Center for his editorial assistance in preparing this manuscript. I also thank Dr. David M. Kent from the predictive analytics and comparative effectiveness center at Tufts Medical Center for his assistance in the statistical analysis used to create Table 2.

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    • Conflicts of Interest: None.

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    2023 Published by Elsevier Inc. on behalf of the American Society of Echocardiography.