What is the clinical significance of a prominent Eustachian (pistachio) valve seen on echocardiography?

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Last updated: October 15, 2026 • View editorial policy

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Prominent Eustachian Valve on Echocardiography

A prominent Eustachian valve seen on echocardiography is typically a benign embryologic remnant with no clinical significance in most cases, but it warrants careful attention because it can be associated with patent foramen ovale (PFO), may facilitate paradoxical embolism, and can be mistaken for pathology during interventional procedures.

Clinical Significance

The Eustachian valve (also called the pistachio valve) is a remnant of the embryonic right valve of the sinus venosus located at the junction of the inferior vena cava and right atrium. While it normally regresses after birth, it persists in approximately 57% of adults 1.

Key Clinical Associations

Association with Patent Foramen Ovale:

  • 70% of patients with a prominent Eustachian valve have a coexisting PFO 1. This strong association (Cohen's kappa = 0.75) occurs because the Eustachian valve directs blood from the inferior vena cava toward the interatrial septum, potentially preventing spontaneous PFO closure after birth.
  • The prevalence of prominent Eustachian valve is significantly higher in patients with presumed paradoxical embolism (68%) compared to controls (33%) 1.

Risk for Paradoxical Embolism:

  • The Eustachian valve may represent an independent risk factor for left circulation thromboembolism beyond that associated with PFO size and shunting alone 2. By directing inferior vena cava blood toward the atrial septum, it can facilitate right-to-left shunting through a PFO.
  • Patients with both a prominent Eustachian valve and PFO may benefit most from percutaneous PFO closure 2.

Potential Complications

Thrombus Formation:

  • The Eustachian valve can serve as an attachment site for thrombi 3. These thrombi may be mistaken for tumors or vegetations on imaging.
  • In some cases, the valve may actually prevent pulmonary embolism by trapping thrombi 3.

Infective Endocarditis:

  • The valve can serve as a site for infective vegetations 3.

Procedural Complications:

  • Critical pitfall: The prominent Eustachian valve can be mistaken for the inferior rim of the atrial septum during ASD assessment, leading to iatrogenic complications during surgical or percutaneous closure procedures 4, 5.
  • This misidentification can result in inadvertent closure of the Eustachian valve to the interatrial septum rather than true ASD closure 5.
  • It may interfere with transseptal interventional procedures 3.

Recommended Evaluation

When a prominent Eustachian valve is identified:

  1. Actively search for PFO using contrast echocardiography with agitated saline, as 70% will have this association 1.

  2. Assess for right-to-left shunting, particularly if the patient has unexplained hypoxemia, cyanosis, or history of cryptogenic stroke.

  3. Carefully delineate the true atrial septum from the Eustachian valve, especially if any interventional procedure is planned. Use multiple echocardiographic views and consider transesophageal echocardiography (TEE) for better anatomic definition 5.

  4. Exclude thrombus or vegetation attached to the valve if clinically indicated (fever, embolic events). TEE with 3D imaging provides optimal visualization 3.

  5. Document the size and mobility of the valve for future reference.

Clinical Management

For asymptomatic patients with isolated prominent Eustachian valve:

  • No specific intervention is required; this is a benign finding.

For patients with prominent Eustachian valve and PFO:

  • If there is history of cryptogenic stroke or paradoxical embolism, strongly consider percutaneous PFO closure, as these patients may be at higher risk than those with PFO alone 2, 1.

For patients undergoing interventional procedures:

  • Ensure the interventional team is aware of the prominent Eustachian valve to prevent misidentification during ASD closure or transseptal procedures 4, 5.

Common Pitfalls to Avoid

  • Do not mistake the Eustachian valve for the atrial septum during pre-procedural planning for ASD closure 4, 5.
  • Do not dismiss the finding in patients with cryptogenic stroke—actively look for PFO and consider the combination as a higher-risk substrate for paradoxical embolism 1.
  • Do not confuse attached thrombus or vegetation with the valve itself—use multiple imaging planes and TEE if needed 3.

References

1
Research

Persisting eustachian valve in adults: relation to patent foramen ovale and cerebrovascular events.

Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography, 2004

3
Research

Delineation of an octopus-like thrombus attached to the eustachian valve.

Echocardiography (Mount Kisco, N.Y.), 2014

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This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.