RT Journal Article SR Electronic T1 An unusual cause of tachyarrhythmia in an otherwise healthy young man JF Heart JO Heart FD BMJ Publishing Group Ltd and British Cardiovascular Society SP 1472 OP 1472 DO 10.1136/heartjnl-2017-311485 VO 103 IS 18 A1 Raouf, Wessam A A1 Shams, Khaled A1 Mansour, Amr YR 2017 UL http://heart.bmj.com/content/103/18/1472.abstract AB Clinical introduction A 32-year-old man referred to the cardiology clinic for palpitations was found to have paroxysmal supraventricular tachycardia (SVT) on 24-hour Holter monitoring. His general and cardiac examinations were unremarkable. A transthoracic echocardiographic study to exclude structural heart disease was performed and showed an abnormal structure in relation to the right ventricular (RV) free wall; however, poor echocardiographic windows precluded proper characterisation. Cardiac MR (CMR) was therefore performed. Cine images (figure 1 and online supplementary videos 1 and 2) demonstrated the abnormal structure. Dynamic pass of contrast (rest perfusion module) showed the sequence of intracavitary enhancement across different cardiac chambers in the horizontal long-axis plane (figure 1 and online supplementary video 3).Figure 1 Still frames from balanced steady state free precession images in the horizontal long-axis plane (A,B). Still frames from the dynamic pass of contrast in the horizontal long-axis and the short axis following contrast injection into the right arm (C,D). Images in the horizontal long-axis plane at the basal level using T2-weighted short-tau inversion recovery (E) and half Fourier single-shot turbo spin echo (F).Supplementary MaterialSupplementary data [cine_shax-ed.mp4] Supplementary MaterialSupplementary data [contrast.avi] Supplementary MaterialSupplementary data [4_chamber.avi] Question The abnormal structure is most likely which of the following?Pericardial cystRight atrial appendage aneurysmRight ventricular aneurysmJuxtaposed left atrial appendageAccessory right ventricular chamberQuestion