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IMAGE–CARDIOLOGY

Mycotic coronary artery aneurysm causing chest pain detected by transthoracic echocardiography: a potential blind spot of routine screening in parasternal short axis view Toshimitsu Kato1   · Noriaki Takama2 · Kazufumi Aihara2 · Tomonari Harada2 · Masaru Obokata2 · Masahiko Kurabayashi2 · Masami Murakami1 Received: 25 July 2020 / Accepted: 28 August 2020 © The Japan Society of Ultrasonics in Medicine 2020

A 48-year-old woman was admitted to this hospital because of chest pain that developed during maintenance hemodialysis. The patient had been undergoing hemodialysis owing to chronic glomerulonephritis since the age of 14 years. Longterm double lumen catheter was implanted 7  years ago because of difficulty in blood access. An electrocardiogram showed ST depression in the II, III, and aVF leads, and ST elevation in the V6 lead. Cardiac enzyme levels were within the normal range. White blood cell counts (21,800/μL) and C-reactive protein levels (22.5 mg/dL) were elevated. Body temperature was 36.8 ℃. Heart murmur was not auscultated. Transthoracic echocardiography (TTE) was performed. Left ventricular (LV) ejection fraction was 60%, and the LV anterior wall was hypokinetic. The parasternal short-axis view (PSAX) showed no abnormal structure (Fig. 1a). However, the parasternal short off-axis view (Off-PSAX) at the midLV level revealed a capsule-like mass on the epicardial side of the LV anterior wall (Fig. 1b). The inside of the mass was echo-free, and the wall of the mass was thick. Doppler imaging showed blood flow into the mass (Fig. 1c, d), suggesting coronary artery aneurysm (CAA). Coronary angiography revealed CAA at the mid-portion of the left anterior descending artery (LAD) (Fig. 1e). LAD blood flow decreased. Emergent surgical CAA resection and coronary

artery bypass were performed. Intraoperative findings revealed that infection was the most likely cause of CAA (Fig. 1f, g), and that the double lumen catheter appeared to be the possible site of infection. The double lumen catheter was exchanged. The postoperative course was uneventful. Staphylococcus aureus, the most common pathogen of mycotic CAA, was the causative bacteria [1]. Four weeks of antibiotic treatment was successful. CAAs are detected incidentally in 0.2–5% of patients who undergo coronary angiography. However, mycotic CAA is extremely rare (3% of all CAAs) and reportedly involved in 0.5% of infective endocarditis [2]. End-stage kidney disease is a risk factor for mycotic CAA [3]. TTE is a useful method for screening CAA around the left main coronary artery [4]. Detecting the blood flow signal inside the CAA using color Doppler imaging is the preferred method for CAA diagnosis [5]. Unlike non-mycotic CAA, mycotic CAA is characterized by a capsule-like structure with a thick wall. However, CAA located around the mid-portion of the LAD is sometimes not visible on routine imaging (Fig. 1a). The Off-PSAX (Fig. 1b) aids screening for mycotic CAAs, especially in high-risk patients or cases with abnormal wall motion around the LAD