LAUSR

A 25-year-old female was referred for echocardiography due to cardiomegaly noted on a chest X-ray after an uneventful delivery. The patient was asymptomatic and the clinical examination was unremarkable. Transthoracic echocardiography showed a ‘snake-like’ structure extending from the aortic root posterior to the left atrium (Fig. 1a, Supplementary Data 1) with continuous systolic and diastolic flow on Doppler (Fig. 1b). A transesophageal echocardiogram showed a dilated left sinus of Valsalva and a ‘tunnel’ posterior to the aorta. A pedunculated right atrial mass measuring 2.5 9 3.7 cm was also noted (Fig. 1c, Supplementary Data 2). On invasive coronary angiography, the aneurysmal sinus gave off normal caliber left anterior descending and circumflex arteries and extended as a giant tunnel towards the right (Fig. 1d, Supplemental Data 3). 64-slice ECG-gated multidetector computed tomography (MDCT) (Fig. 1e, Supplementary Data 4) revealed that the tunnel took a course posterior to the ascending aorta and divided into two branches. The superior branch drained into the superior vena cava while the inferior branch drained into the right atrium at the level of a hypoattenuated right atrial mass; this was noted to enhance with contrast (Fig. 1f, Supplementary Data 5), demonstrating that the right atrial mass was a continuation of the tunnel. A left to right shunt of 1.2 was estimated. The patient refused intervention and has remained asymptomatic. Aorto-right atrial tunnels (ARATs) are a rare congenital anomaly of which the embryology and etiology remain unclear. Tunnels arising from all three sinuses of Valsalva and draining into the right atrium have been described [1]. This ARAT appeared to be draining into a right atrial mass, possibly a benign endocardial hemangioma. Hemangiomas make up 5–10% of primary intracardiac tumors, which have an incidence of 0.001–0.3% [2]. Gajjar et al., however, proposed that ARATs arise from a defective area in the aortic wall forming an extracardiac tunnel and rupturing into the right atrium because of anatomic proximity and low filling pressure [1]. Interestingly, a histological examination taken from one ARAT showed aortic tissue [3]. This explanation, however, fails to explain drainage via a suspected hemangioma as in our case. ARATs have also been associated with secundum-type atrial septal defects and patent ductus arteriosus. This is the first case description of an ARAT draining into a right atrial pedunculated mass and demonstrates the importance of multi-modality imaging in investigating these structures. Electronic supplementary material The online version of this article (doi:10.1007/s12574-017-0328-6) contains supplementary material, which is available to authorized users.