Dynamic Mercedes-Benz Sign in the Right Atrium

Ryo Tanabe1,2, Hiroki Matsuura3, Yuki Otsuka2, and Akira Endo1
1Department of Surgery, Watanabe Hospital, Okayama, Japan
2Center for Graduate Medical Education, Okayama University Hospital, Okayama, Japan
3Department of General Internal Medicine, Okayama City Hospital, Okayama, Japan

Corresponding author: Ryo Tanabe,

DOI: 10.31662/jmaj.2020-0025

Received: April 3, 2020
Accepted: July 20, 2020
Advance Publication: October 2, 2020
Published: October 15, 2020

Cite this article as:
Tanabe R, Matsuura H, Otsuka Y, Endo A. Dynamic Mercedes-Benz Sign in the Right Atrium. JMA J. 2020;3(4):353-354.

Key words: Dynamic Mercedes Benz sign, Venous air embolism, Venipuncture

An 87-year-old woman with an acute history of fever and cough presented to our emergency department. Non-contrast chest computed tomography (CT) revealed the unexpected presence of air in the right atrium (Figure 1A). Air embolisms in the heart are observed as the Mercedes-Benz sign (1), which is commonly observed in gallstones. This sign is not usually detected via electrocardiography-synchronized CT because its motion artifact is due to the heartbeat. They are detected via unenhanced chest CT in no less than 5.5% of asymptomatic patients after securing a peripheral venous line (2). Patients with a patent foramen ovale are at a risk of end-organ ischemia due to venous air embolism. Clinicians should be aware of the possible complication of venipuncture and should carefully follow-up patients who present with a Mercedes-Benz sign regardless of additional symptoms, such as paralysis. Our patient did not exhibit additional symptoms. Air was not observed on the follow-up CT 2 days later (Figure 1B).

Figure 1. A. Electrocardiography-asynchronized computed tomography (CT) showing unexpected air (dynamic Mercedes-Benz sign) in the right atrium.
B. Air was not observed on the follow-up CT performed 2 days later.

Article Information

Conflicts of Interest


Author Contributions

Ryo Tanabe contributed to manuscript preparation, patient care, and discussion. Hiroki Matsuura, Yuki Otsuka, Akira Endo contributed to the discussion on the definitive diagnosis.

Informed Consent

Informed consent has been obtained from the patient for the publication of their information, including photographs.

Approval by Institutional Review Board (IRB)

This study did not require IRB approval.


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