Logan Pyle, Vasisht Srinivasan, Kelly Rath, Jordan Bonomo
A 30-year-old man with a past medical history of polysubstance drug abuse, chronic Candida bacteremia and endocarditis status post mitral valve (MV) replacement, prior right middle cerebral artery stroke, and left posterior cerebral artery aneurysm rupture (presumed mycotic) presented to an academic tertiary care hospital in January 2020 with abdominal pain and transaminitis after coil embolization for hepatic pseudoaneurysm. While on the surgical service he developed acute right hemiparesis due to a left parietooccipital intracerebral hemorrhage with midline shift. Angiography revealed an underlying mycotic aneurysm and he underwent emergent left decompressive hemicraniectomy, clot evacuation, and aneurysm clipping. He was then admitted to the neurocritical care unit for further management. There was no significant growth of bacteria in his blood cultures, and the infectious disease team recommended lifelong antifungal therapy for his chronic Candida bacteremia.
A point-of-care ultrasound examination was performed, which revealed a mechanical MV, a thickened and hypokinetic left ventricle (LV), a moderately enlarged right ventricle (RV) with normal appearing function, a patent pulmonary artery (PA) up to the bifurcation, and a persistent eustachian valve (EV), which prompted the performing neurocritical care team to ask, “What the heck is that in the right atrium?”
This image of the persistent EV in the study patient is from an RV inflow orientation. This view is achieved by first obtaining the standard parasternal long axis view, then angling the probe toward the patient’s right hip, tilting the ultrasound plane anteriorly. In this view, the RV, tricuspid valve (TV), RA, and superior vena cava (SVC) are identified. This view also permits visualization of the Eustachian Valve which is shown in Figure 1 projecting prominently between the SVC and RA.
This image shows the standard apical 4 chamber view. In this patient, the persistent eustachian valve appears to completely bisect the RA. The left atrium (LA) is obscured by shadow artifact from the patient’s mechanical mitral valve.
Evidence, Pathophysiology, Views, and Differential Diagnoses
Eustachian valves are a remnant of the embryonic right heart and direct blood from the inferior vena cava across the patent foramen ovale (PFO) into the systemic circulation in utero, and typically degenerate after birth. Persistent EV are common in patients with paradoxical emboli, with a 57% incidence in patients with paradoxical stroke1,2 and are prevalent in healthy populations as well.3,4 Persistent EV also correlate with a higher incidence of PFO.5-7 Point of Care Ultrasonography (POCUS) can be useful in identifying cardiac sources of emboli such as persistent EV in real time. However, providers must be cautious as there are multiple findings that may difficult to differentiate from EV, including intracardiac thrombus or mass, beam artifact, or Chiari network.8,9
Infective endocarditis (IE) can involve native or prosthetic valves, any intracardiac devices within the heart and, at times, EV. The annual incidence of IE has been steadily on the rise, now affecting 15 out of 100,000 people per year.10 Persistent eustachian valves have an association with infective endocarditis, and are associated with isolated right-sided endocarditis only around 3% of the time.11 A hypothesized etiology of the increased infection rate in EV is structural abnormality leading to turbulent blood flow near the valve. While Staphylococcus aureus is the most common pathogen, infections with Escherichia coli, Proteus vulgaris, Enterobacter species, and Streptococcus viridans have also been described.12,13 Most cases are diagnosed with transesophageal echocardiography, but persistent EV can at times be identified with transthoracic echocardiography, as was the case in this patient.13,14
Standard management of infective endocarditis is recommended for EV associated endocarditis. Traditionally, anti-microbial therapy alone is sufficient to treat EV IE.15-18 As in other cases of infective endocarditis, follow up blood cultures and echocardiography are often performed to document resolution of the infection. Indications for surgery may include RV- inflow obstruction causing hypoxemia and/or dysrhythmia, and structural impedance of the IVC during cardiac surgery/cannulation.18-20
While uncommon, persistent eustachian valves can be seen on both POCUS and comprehensive echocardiography examinations. The structure is important to identify as a potential nidus of infection, thromboembolism, and as a marker of concomitant PFO. The authors recommend incorporating the RV inflow view as part of the POCUS echocardiographic examination to evaluate the RA more completely in appropriate patients.
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- Shmueli H, Thomas F, Flint N, Setia G, Janjic A, Siegel RJ. Right-Sided Infective Endocarditis 2020: Challenges and Updates in Diagnosis and Treatment. J Am Heart Assoc 2020;9:e017293-e.
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